Exploring the Crank/Hub/Prop Separation phenomenon
Please note that the following comments are in no way meant to put Aerovee in a bad light or any other company in a good light.I just found them interesting in their own right .I will fly behind an Aerovee with no qualms but I haven't decided whether I want to build one.Learn with an open mind.
A letter from the CEO of Sonex Jeremy Monnett as posted to sonextalk
Note what I have highlighted in red. A very positive statement on longevity!
Hello AeroVee Group-
Sonex has been following the discussion on Propeller Hubs and felt it was
time to give our $.02.
I personally believe that those that have a preference for a Force-One type
prop hub do not understand the shrink fit design of the AeroVee and probably
have not even seen it. I would encourage those who have concerns to have a
look at the components that comprise the installation (and the entire
AeroVee Conversion for that matter) which will result in an immediate
feeling of strength, simplicity, and elegance in form and function. We
always have a forum and Booth at AirVenture and have an entire presentation
on Engine Development as part of the Sonex Workshop.
As was already pointed out on these lists, Aircraft engines of all types,
including type certified engines have had mechanical failures of all types.
None of us that design, build, test, and sell engines and engine conversions
want to see a single failure, but they happen. Our job is to learn what
caused them and, when appropriate, issue Service Notices and/or Product
Changes if we feel they are warranted.
As stated before on these lists, we continue to fly 6 of our AeroVee Engines
in factory Sonex aircraft and have been flying successfully behind our same
basic shrink-fit hub design for 9 years and thousands of hours. 5 of the
factory installations are the AeroVee 2180/2.0 design and 1 of the factory
installations is the newest AeroVee 2.1. The most common concern we heard
from customers was with their ability to successfully achieve the shink-fit
installation, which we answered by now offering an "Assembled Crank Shaft"
on the AeroVee 2.1:
http://www.aeroconversions.com/products/aerovee/
We appreciate the efforts of those who continue to root out the
misinformation that is all too readily spread amongst egroups and builder
forums. Sonex agrees that sticking to facts is always the best course of
action when discussing any company's products.
On the latest posting from Don Boll, we are disappointed that he chose to go
public with this before a thorough investigation could be conducted, but
that was his choice. The only response we have at this time is that the
"rate of failures" that Don is suggesting is high in the AeroVee is
absolutely not. To make a statement like this based on no knowledge of the
service record of the product is irresponsible and incorrect. We have
requested the component parts involved in this incident be returned to Sonex
for a thorough analysis. To date, they have not been returned. The results
of this analysis will be shared with this group. We can tell from the
pictures Don has provided that the prop hub was from an AeroVee 2180.
As always, please feel free to contact Heather, Betty, John, Kerry, Mark,
Jason, Stephanie, or myself at the numbers or e-mail below with any
questions or comments.
Regards,
-jeremy
--
Jeremy Monnett
CEO
Sonex Aircraft, LLC
www.sonexaircraft.com
Tel (Info/Orders): 920.231.8297
Tel (Tech Line): 920.230.8324
Fax: 920.426.8333
E-mail: jeremy@...
AND THIS WOULD BE THE OFFENDING POST FROM MR BOLL I BELIEVE
My Aerovee with 100 hours on it let go of the crank just
behind the key way and in front of the oil slinger. I was
cruising 120mph 3100 rpm , 1000 ft. A slight vibration was
felt and I immediate reduced power at the same time a loud
band in the cowl told me the crank had let go. I had just
done a pre flight as this was the first flight since
last fall. I was over farm land covered 40% in water from
spring run off, but was able to land with out any damage to
the aircraft or property. I notified Jeremy, and said I
not l to go public with this till we could
determine the cause. The prop and hub landed in a 30 acre
slough in 30 in of water and recovery was not possible till
last week.
The prop bolts and hub bolt where secure with no singe of
loosens. When I installed the prop hub, I had no
difficulties what ever. My brother and I worked closely
together in his shop. The deepfreeze and an oven where right
next to the work bench and all went together as per
instructions. This was text book installation and I could
never figure out why some where struggling with this.
All that said, I still do not want to try to judge what the
case of the separation was. It really doesn’t matter if it
was
the installation of the hub, poor material, or poor design,
this type of thing is happening and not always coming to our
attention. That is the reason for this report. Some one is
going to get killed at the rate of failures and we need to
get to the bottom of this. Jeremy has requested that I
send him the case, crank shaft and hub witch I will do.
Sonex will report there findings, so up to that time
speculation will get us no ware. The new version of the
crank
shaft appears to be an improvment.Time will tell. As for
now.PLEASE CONSIDER THE RISK YOU ARE TAKING BEFORE YOUR NEXT
FLIGHT. If the prop would have fallen on someone a death
could
have occurred, if I would of landed in the water a flip over
could have happened.
Please, before we get involved in a lot of flaming towards
myself or the fine people at Sonex, lets wait for the
results from there testing.
Don Boll
Sonex 396
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sonex has been following the discussion on Propeller Hubs and felt it was
time to give our $.02.
I personally believe that those that have a preference for a Force-One type
prop hub do not understand the shrink fit design of the AeroVee and probably
have not even seen it. I would encourage those who have concerns to have a
look at the components that comprise the installation (and the entire
AeroVee Conversion for that matter) which will result in an immediate
feeling of strength, simplicity, and elegance in form and function. We
always have a forum and Booth at AirVenture and have an entire presentation
on Engine Development as part of the Sonex Workshop.
As was already pointed out on these lists, Aircraft engines of all types,
including type certified engines have had mechanical failures of all types.
None of us that design, build, test, and sell engines and engine conversions
want to see a single failure, but they happen. Our job is to learn what
caused them and, when appropriate, issue Service Notices and/or Product
Changes if we feel they are warranted.
As stated before on these lists, we continue to fly 6 of our AeroVee Engines
in factory Sonex aircraft and have been flying successfully behind our same
basic shrink-fit hub design for 9 years and thousands of hours. 5 of the
factory installations are the AeroVee 2180/2.0 design and 1 of the factory
installations is the newest AeroVee 2.1. The most common concern we heard
from customers was with their ability to successfully achieve the shink-fit
installation, which we answered by now offering an "Assembled Crank Shaft"
on the AeroVee 2.1:
http://www.aeroconversions.com/products/aerovee/
We appreciate the efforts of those who continue to root out the
misinformation that is all too readily spread amongst egroups and builder
forums. Sonex agrees that sticking to facts is always the best course of
action when discussing any company's products.
On the latest posting from Don Boll, we are disappointed that he chose to go
public with this before a thorough investigation could be conducted, but
that was his choice. The only response we have at this time is that the
"rate of failures" that Don is suggesting is high in the AeroVee is
absolutely not. To make a statement like this based on no knowledge of the
service record of the product is irresponsible and incorrect. We have
requested the component parts involved in this incident be returned to Sonex
for a thorough analysis. To date, they have not been returned. The results
of this analysis will be shared with this group. We can tell from the
pictures Don has provided that the prop hub was from an AeroVee 2180.
As always, please feel free to contact Heather, Betty, John, Kerry, Mark,
Jason, Stephanie, or myself at the numbers or e-mail below with any
questions or comments.
Regards,
-jeremy
--
Jeremy Monnett
CEO
Sonex Aircraft, LLC
www.sonexaircraft.com
Tel (Info/Orders): 920.231.8297
Tel (Tech Line): 920.230.8324
Fax: 920.426.8333
E-mail: jeremy@...
AND THIS WOULD BE THE OFFENDING POST FROM MR BOLL I BELIEVE
My Aerovee with 100 hours on it let go of the crank just
behind the key way and in front of the oil slinger. I was
cruising 120mph 3100 rpm , 1000 ft. A slight vibration was
felt and I immediate reduced power at the same time a loud
band in the cowl told me the crank had let go. I had just
done a pre flight as this was the first flight since
last fall. I was over farm land covered 40% in water from
spring run off, but was able to land with out any damage to
the aircraft or property. I notified Jeremy, and said I
not l to go public with this till we could
determine the cause. The prop and hub landed in a 30 acre
slough in 30 in of water and recovery was not possible till
last week.
The prop bolts and hub bolt where secure with no singe of
loosens. When I installed the prop hub, I had no
difficulties what ever. My brother and I worked closely
together in his shop. The deepfreeze and an oven where right
next to the work bench and all went together as per
instructions. This was text book installation and I could
never figure out why some where struggling with this.
All that said, I still do not want to try to judge what the
case of the separation was. It really doesn’t matter if it
was
the installation of the hub, poor material, or poor design,
this type of thing is happening and not always coming to our
attention. That is the reason for this report. Some one is
going to get killed at the rate of failures and we need to
get to the bottom of this. Jeremy has requested that I
send him the case, crank shaft and hub witch I will do.
Sonex will report there findings, so up to that time
speculation will get us no ware. The new version of the
crank
shaft appears to be an improvment.Time will tell. As for
now.PLEASE CONSIDER THE RISK YOU ARE TAKING BEFORE YOUR NEXT
FLIGHT. If the prop would have fallen on someone a death
could
have occurred, if I would of landed in the water a flip over
could have happened.
Please, before we get involved in a lot of flaming towards
myself or the fine people at Sonex, lets wait for the
results from there testing.
Don Boll
Sonex 396
--------------------------------------------------------------------------------------------------------------------------------------------------------
I had posed a question in the Aerovee forum as follows Hi
From: aerovee@yahoogroups.com [mailto:aerovee@yahoogroups.com] On Behalf Of
Windsor
Sent: Saturday, August 13, 2011 3:33 PM
To: aerovee@yahoogroups.com
Subject: [aerovee] prop/hub saga
Hi guys.I am building an Onex and am undecided about the engine I will use.
does anyone have a figure as to how many prop hub failures there have been
on the aerovee 2.1 installation.I am not interested on the earlier version
2.0.At this point I am not concerned about the why eg; Builder error or oil
starvation.Just a number. Is there an faa accident site that can access this
info whereby you can plug aerovee into the search and come up with all the
aerovee engine data?
Thanks in advance and please don't take this as a slight to aerovee.I am
simply trying to distinguish fact from fiction.
Mike.I a
Well It caused a slight commotion and Sonex jumped in with this reply in both aerovee and sonextalk
What i have highlighted in red is the answer I have been looking for ,I think?.In essense Sonex is stating categorically that there has Never Been A failure of an aerovee crankshaft assembly.
From: Sonex Aircraft, LLC <jeremy@...>
Subject: [sonextalk] AeroVee Crank Shaft and Prop Hub vs. the Competition.
To: ""sonextalk@yahoogroups.com"" <sonextalk@yahoogroups.com>,
""aerovee@yahoogroups.com"" <aerovee@yahoogroups.com>
Date: Tuesday, August 16, 2011, 6:14 PM
Hello again AeroVee and Sonextalk Groups-
Sonex Aircraft will continue to study the recent crank shaft break, which
has been quoted on these lists going on 2 weeks now...again providing the
incorrect perception that this is a widespread problem.
We hope that our competitors who have long claimed to have a superior
product will reveal the problems and failures that they have had with their
crankshaft assembly. It should be further noted that the AeroVee continues
to dominate the VW Conversion Market, so there are simply many, many more in
the field...it's a much larger sampling to take data from.
I personally believe that those that have a preference for a "Force-One"
type prop hub do not understand the shrink fit design of the AeroVee and
probably have not even seen it. I would encourage those who have concerns to
have a look at the components that comprise the installation (and the entire
AeroVee Conversion for that matter) which will result in an understanding of
the strength, simplicity, and elegance in form and function. We
always have a forum and Booth at AirVenture and have an entire presentation
on Engine Development as part of the Sonex Workshop.
As was already pointed out on these lists, Aircraft engines of all types,
including type certified engines have had mechanical failures of all types.
None of us that design, build, test, and sell engines and engine conversions
want to see a single failure, but they happen. Our job is to learn what
caused them and, when appropriate, issue Service Notices and/or Product
Changes if we feel they are warranted.
It is also the owner/operator's responsibility to accurately and truthfully
report all circumstances surrounding an incident so a proper and well
informed investigation can be made, and facts, not speculation, reported to
the fleet owner's. Too often pride or the desire to blame others prevents
this from happening.
As stated before on these lists, we continue to fly 8 of our AeroVee Engines
in factory Sonex aircraft and have been flying successfully behind our same
basic shrink-fit hub design for 11 years. 5 of the factory installations are
the AeroVee 2180/2.0 design and 3 of the factory installations are the
newest AeroVee 2.1. Our competitors in the vw conversion business do not
maintain a fleet of test engines and do not regularly fly behind their own
engines.
The most common concern we heard from customers was with their ability to
successfully achieve the shink-fit installation, which we answered by
offering an "Assembled Crank Shaft" on the AeroVee 2.1:
http://www.aeroconversions.com/products/aerovee/
We appreciate the efforts of those who continue to root out the
misinformation that is all too readily spread amongst egroups, builder
Forums, and fly-ins and builder gatherings.. Sonex agrees that sticking to
facts is always the best course of action when discussing any company's
products.
There are 2 versions of the AeroVee Crankshaft Assembly:
The AeroVee 2180/2.0 version was sold from 2001 through 2008
The AeroVee 2.1 version with a custom crankshaft and hub has been
shipping since 2008.
To date, there has never been a failure of either a factory-assembled
AeroVee Crankshaft (2180 , 2.0 or 2.1) or of any 2.1 AeroVee Crankshaft
Assembly including all customer-assembled units.
As always, please feel free to contact Betty, John, Jeremy, Kerry, Mark,
Heather , Jason, or Stephanie at the numbers or e-mail below
with any questions or Comments.
After spending a lot of time and search effort on this issue I now consider it a non-issue.I am satisfied that Flying behind an Aerovee is no more dangerous than flying behind the competition.In the few accident reports I could gleen ,only one admonished Sonex for not giving instruction how to remove the hub from the crankshaft and what must be done/checked before re-attaching it.Sonex claims that they have rectified this .
So bottom line if your concerned about it have Sonex attach the hub for you,and fly behind it with peace of mind.It's what I intend if I decide to purchace the Aerovee
Mike
PS; I found this and decided to add it post mortem :)
http://ereksonfamily.org/sonex/aerovee-engine/vw-prop-hub-on-aerovee/
or read it here
VW prop hub on AeroveeThe issue has arisen many times about Prop Hubs on VW engines and the lack of bearing surface.
This post occurred on one of the Sonex yahoo groups:
VW Cranks (Was Re: Sonex Incident – 9/29/2007)
Frank,
I have sat back too and read this thread on the
VW problems ….part of me just said to keep
quiet …..but the other parts says to share what
you know …..I am no expert but 20+ years of aero
vw use has taught me some stuff ……so here goes;
You hit the nail on the head here. However the VW
with a stock crank and shrink-fit hub works very
well on engines up to 1915cc …..I know because
I have flown behind them for 20+ years, the added
torque of the 2180 increases the risk of failure,
and many of the guys I call experts agree.
I have an Aerovee 2180, I like the looks of it and
I like the package as a whole. When I bought mine
I knew I was going to discard the AeroVee crankshaft
and shrink-fit prop hub!
I immediately sent the block to Steve at Great Plains
and had the block machined for the Force One Prop Hub,
I also purchased his aircraft purpose-built 82mm forged SCAT
crankshaft. It was designed to have the extra
metal in the area of failure, and they have never
had one fail to date. They use it on 2300cc VW’s.
There is nothing wrong with the VW, but building a
2180cc engine begins to exceed the strength of the base
engine it’s built from. My last 2180cc VW engine had over
1400 hours on it when I sold it ….and it was built by me
from parts I purchased from CB Peformance with the
exception of the crankshaft and prop hub, these came
from GreatPlains!
All my VW engined planes to date were single seat aircraft,
but my SONEX will carry passengers (wife and children) so I
spent the extra money to insure my engine stays together.
Nothing against Sonex / Aerovee, but the VW engine was NOT
designed by them, so they are NOT the last word on anything
VW. They put together a nice package and it’s a really
nice engine, but they know of the possible issues with
the VW crankshaft design with a shrink-fit prop hub, they
are aware ….that’s why they stress correct prop hub installation,
the Aerovee is not their first use of the aero-vw engine!
Even when installed correctly as per Aerovee, the design is
marginal …NOT bad …but marginal! There is room for error
that can cause failure. One of the established installation
procedures and setup is the have the front 2 cylinders at
TDC ….(pistons out towards the cylinder heads) and install
the prop in a horizontal postion, plus insure the prop
tacks true. This will increase the survival rate of the
prop hub. Also it has been found that keeping the prop
length 55″ and below is safer. These are just common VW
engine practices by others ……the big practice is to
use wooden props only! This one is obvious but I felt it
needed said as not everyone here will buy a prop from Sonex.
While on the subject there is a SERVICE Bulletin on
all VW Supercases, the #4 bearing oil feed has been found
to be improperly sized / installed on 1 out of every 4 new
cases. The #4 bearing is the small bearing behind the
prop hub …..this has not been attributed to the prop
hub / crankshaft failures but needs resolved for long
engine service. Contact Steve Bennett at GreatPlains if you
want a better explanation.
It’s a simple fix, can be done with the engine in the plane. You
drill out an oil plug, internally remove the restrictor
plug and install a screw in plug. Steve at Great Plains
reminded me of this …..and “my Aerovee block” was one of the
defective ones. He fixed it while he had it in his shop.
While I love my Sonex and the Aerovee, it’s NOT a perfect
powerplant as received from Sonex. The Aerovee 2180 is just
assembled from off-the-shelf components internally. The
Aerovee specific stuff is outside of the engine, all the
pretty red anodized parts, the Aerovee Carb and there sort
of neat ignition system …….all nice stuff!
I have flown behind VW engines for a long time, and I have
lost a prop hub on an early Monnett engine (before Aerovee)!
I don’t plan to loose another ….of anybodys manufacture!!!
I don’t worry about warranty, there really is none once
the engine is flying ….I am currently NOT using the AeroCarb
either, I use an EFI system from SDS (Simple Digital Systems).
I don’t have cooling problems and have never had any, the
EFI precisely controls the mixture …..it starts on the
second rotation of the prop, even at 20 degrees …..I have
run it on Ethanol …just a programming change to switch
between fuels. Yes, EFI is more complicated, yes it has an
electric fuel pump ..(I use redundant pairs)…but it is as
reliable as anything out there, I have been using this system on
some other aero engines as well as the VW for 4 years …..
the SDS system is aircraft quality …and is not cheap, but
I prefer EFI!
Not going to argue any of this, just sharing what I know
on the subject! You have a question I’ll be glad to answer
it ….just too old to debate stuff that I have learned the
hard way!
My 2 cents!
Les
Sonex #1094
--------------------------------------------------------------------------------------------------------------------
Generated this response:
Hello again Sonextalk Group-
As promised, we wanted to address some of the comments made the past couple
of days on the AeroVee Design. We feel these comments need to be responded
to, especially those that are misleading and provide limited background
information. We provided our responses after the quoted text excerpts from
these postings.
>You hit the nail on the head here. However the VW
>with a stock crank and shrink-fit hub works very
>well on engines up to 1915cc …..I know because
>I have flown behind them for 20+ years, the added
>torque of the 2180 increases the risk of failure,
>and many of the guys I call experts agree.
=As addressed in the past, there is very little “stock” about an AeroVee
Engine Core. Nearly 100% of the component parts are aftermarket component
parts. The Crankshaft is forged -and Nitrtrided- 4340 Steel. A common
misunderstanding (even from those that claim to be vw experts) are the real
loads that need to be addressed in designing conversion components for the
VW Core. The Modern AeroVee Conversion exists today because of the many
shortcomings of the existing conversions that were offered by other
manufacturers in the late 1990′s. The AeroVee has been challenged in
rigorous flight testing under the highest stress flight
situations…including Aerobatics. Most pilots do not engage in this kind of
flying. We insist on testing our installations in these most rigorous
conditions.
>All my VW engined planes to date were single seat aircraft,
>but my SONEX will carry passengers (wife and children) so I
>spent the extra money to insure my engine stays together.
=There have been many thousands of rides given in AeroVee Powered Aircraft
of all types. There is no need to speculate that the AeroVee Prop Hub design
somehow makes the aircraft unsafe. This is an irresponsible comment and an
irrational concern not based on fact, but purely speculation and opinion. An
AeroVee Shrink Fit Prop Hub installed and maintained properly yields the
highest strength and simplest installation on any VW Engine Conversion.
>While on the subject there is a SERVICE Bulletin on
>all VW Supercases, the #4 bearing oil feed has been found
>to be improperly sized / installed on 1 out of every 4 new
>cases.
=This Service Bulletin on the #4 Bearing is many years old. We have not
encountered any cases in the many hundreds that have come through our
factory that have this issue. If this was a true service issue, there would
be many vw vehicles stuck on the side of the road that you would be passing
on a routine basis.
>While I love my Sonex and the Aerovee, it’s NOT a perfect
>powerplant as received from Sonex.
=There is no manufactured product or Aircraft Conversion that does represent
the perfect powerplant or the perfect product. However, the great success of
the AeroVee can be attributed to its combination of simplicity,
reliability,and light weight in an extremely robust and well proven package.
It’s the pursuit of perfection that most distinctly separates
AeroConversions and Sonex products from the competition. We promise that as
opportunities present themselves, we will continue to improve and expand
our product lines as any reputable and successful aircraft manufacturer
would.
> about warranty, there really is none once
>the engine is flying
=I’m not sure where the information about a warranty expiring once an
AeroVee Flies was obtained. This is completely false. If a part is found to
be defective in an AeroVee whether it is flying or not, there most
certainly is warranty coverage. Obviously, if you modify the component parts
or if the builder is found to be the one that caused the problem, then the
replacement cost on parts are your responsibility.
Spending $1500+ on a Fuel Injection System for your AeroVee makes absolutely
no sense to us whatsoever….especially if it’s put on a Sonex, Waiex, or
Xenos set up for Gravity Feed. We have many thousands of hours flying with a
smooth running, low fuel burn, no carb heat, no mixture problems and no
overheating using the standard AeroCarb. For our factory aircraft located in
Oshkosh, WI we make two carb adjustments per year. One approx. 1/4 turn
needle adjustment in the spring as it warms up and one 1/4 turn needle
adjustment in the fall as the air becomes cooler and denser… without the
complication of vapor-lock prone fuel pumps, which do have a tendency to
fail even if they are run in a redundant configuration. Gravity hasn’t
failed us yet…it if does, we certainly have bigger things to worry about.
The reason the AeroVee is sold as a kit is that we back the system as a
whole. If a builder makes modifications to the engine (i.e. Prop hub,
induction system, etc), unfortunately the AeroVee Name is still on the
engine package. If and when an individual has a failure and these
modifications are not revealed on an accident report, then its the AeroVee
Name that loses credibility. This is the same reason that AeroVee
Components are not sold individually to be used on hodge-podge engine
conversions usually done by individuals who have no flight or design
experience with auto conversion engines.
We look forward to continuing to hear flight success stories and supporting
all of our customers in completing their dreams of building and flying their
own aircraft.
As always, please feel free to contact Betty, Heather, Mark, Kerry, John,
Jason, Kristy or myself at the numbers or e-mail below with questions or
comments.
Regards,
-jeremy
–
Jeremy Monnett
CEO
Sonex Aircraft, LLC
www.sonexaircraft.com
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notice carefully the selective quoting of the original post, and the essential failure to address the key issue, the reliability of the shrink fit hub, and the exactitude it requires.
R.S. Hoover , known to a generation of Volkswagen enthusiasts as Veeduber@, has put together this little history of putting props on VW engines. The Aerovee hub is, in Mr. Hoover’s lexicon, Thick (or heavy) Walled Shrink Fit hub. I believe it is long, per his example figure 9. Mr Hoover suggests some possible failure modes. I’d like to suggest another.
Using this calculator, and a lot of assumptions and estimates, I found that the allowable fit tolerance between the nose of the crank and the ID of the hub was uncomfortably small. The new tolerance on the nose of the crank, from VW back in the day was about 9 ten thousandths of an inch, I.E. the #4 bearing journal could be as small as 1.5739 inch or as big as 1.5748. For the shrink fit to work, the frictional forces between the hub and the shaft have to be high enough to withstand the torque to be transmitted, AND the hoop stresses induced have to be low enough to keep the hub from failing due to fatique. Again, using fishy dimensions I SWAG’d from pictures of the Aerovee hub, known dimensions of VW cranks, allowable stresses for common grades of steel, I found that the allowable tolerance on the fit was LESS than the tolerance on the crank itself. And aftermarket VW parts are not known for holding close tolerances.
I encourage others, particularly someone with an AeroVee hub handy to measure to an accuracy of .0001″, to work through the calculations themselves, and report the results to the rest of us. An undergraduate education in mechanical engineering MAY help in deciphering the calculations, but those not burdened by such can probably puzzle their way through it
To wrap it up, I believe the AeroVee long and thick shrink fit hub CAN work IF the crank and the hub are measured and matched to a high degree of accuracy. There are at least 100 AeroVees that ARE flying, some with hundreds of hours. I’ve chosen to drive my prop from the flywheel end of my engine. It’s not flown yet, and there are very few converted VW engines of this configuration that have.
Labels: aviation
posted by flybynightkarmarepair @ 8:24 AM 2 Comments
2 Comments:
At 12:58 PM , Blogger Soloflyer62 said…
Hello,
Since the original Post was mine I wanted to add a few points that need to be clarified and may NOT have been brought out in what you
posted. I have a mechanical engineering degree …so math is something I can do easily.
What this all comes down to is how much margin for failure are you comfortable with. If you prefer, what odds of failure can you live with? 1 in 50? 1 in 500? 1 in 10,000? I want the max safety margin I can afford, but that’s
just me.
First, it’s NOT the prop hub that fails. It’s the crankshaft, so let’s call it what it is, a “crankshaft failure”.
The shrink fit hub is NOT new or an Aerovee design, it has been used on airplanes for a many many years …..the shrink fit hub is just NOT a new item. There have been many attempts to improve on the simple concept, but it is still basically the same as it was 20 years ago.
Again, the reason for most failures has NOT been the actual failure of the prop hub, but the failure is the stock VW crankshaft design and there are several key issues that all contribute to a failure and ultimate separation of the hub / prop from the engine.
#1 The prop hub only slides onto the crankshaft just less than 1 inch. That creates a great deal of mass when the prop is installed hanging out in front of the crankshaft unsupported. Think about it for a minute ….!
#2 The prop hub end of the stock VW crankshaft has a rather large threaded hole bored down the middle of it to retain a bolt for a pulley on the VW engine in the automotive configuration. This hole
goes fairly deep into the crankshaft ….on the outside of the crankshaft (same end) is a keyway groove cut into the OD of the crankshaft …..there is an area of this end of the crankshaft where the threaded hole down the center and the keyway groove almost meet, There is approx 1/8th
of an inch of crankshaft metal between the keyway groove and the threaded hole. The prop hub is slipped right over crankshaft but
does NOT cover this weakened area,
it basically stops right even with this weakened area of the crankshaft. The area I am talking about is just in front of the crankshaft oil slinger disc ….when you install the prop hub you press it right up against the oil slinger disc …..a nice
clean place to break is provided, and that is where they break,
approx. 1/8th of an inch in front of the oil slinger. The crankshaft is almost designed to break here, but this is by accident, NOT intentional, it’s just an automotive part not designed to carry this kind of load. The good
thing is that the metal the crankshaft is made from is very rugged …and you have to create
a situation for it to crack …
and we do just that …read on.
If all things are perfect, hub pressed on correctly, propeller perfectly balanced and tracking true ….the #4 bearing getting good oil for cooling and lubrication, most of the time there
is no issue, everything works in harmony, but …..if there is a flaw in the crankshaft casting, the hub is not installed perfectly,
the propeller is NOT pefectly balanced and tracking true, the #4 bearing is not getting adequate lubrication…. a slight
vibration starts to fatigue the
crankshaft …a crack forms in the area described earlier between the keyway slot and the threaded hole bored down the center of the crankshaft …..once the crack grows long enough to bridge the area between the keyway slot and the threaded crankshaft hole …the crank fails
and the prop hub comes off in flight.
It is believed that bigger engines have accelerated this failure somewhat due to the increased torque and strength of the firing pulses of the engine …and failures have or will increased in numbers. 20 years ago an 1835 cc VW was big, today the 2180cc and 2300cc VW’s are common place. We have not mentioned the junk cast crankshafts that once flooded the market ….we are just talking about the current design of the market’s shrink fit prop hub and a stock VW crankshaft design.
Some VW prop hub crank failures don’t happen until the engine has several hundred hours on them. So
there are a large number of VW based engines that have not reached this point yet ……so don’t think it won’t or cannot happen ….time will tell. I prefer
to be pro-active, if there is a problem …it will happen to me, I am one of those guys ….so I acted, but when it comes to safety I have no problem spending some extra money.
I mentioned a safety margin in my original post, it is here that I feel there is room for improvement.
If everything is not exactly perfect with the crankshaft from
the manufacturer, if the prop hub
is not fully heated and installed within the first try at installing it, if the prop is not perfectly balanced and running true ….the risk of failure of the crankshaft is increased many times over ……and we all know that these are experimental aircraft and engines we are talking about …..most folks do not have the nice shop equipment, shop ovens, IR temp guns, hydraulic presses ….most are do-it-yourself folks with often just common hand tools …so the design needs to be goof proof,
with a large margin for safety, in case something less than ideal is
encountered during the building process…and heaven forbid goes undetected. Maybe the engine kit seller should build this assembly for the kit builder since it’s so critical ….that has got to be an improvement, right? In my simple mind, if a step or process has serious consequences, steps should be taken to insure success and safety, and the old shrink fit prop hub on a VW crankshaft of stock dimensions has possible failure written all over it, it did 20 years ago …and even thought it’s better today than it was it’s still an issue. Just a simple comment but my local FAA rep hates VW engines with shrink fit hubs ….the guy has seen plenty of props come off ….enough said!
The shrink fit hub on a standard dimension VW crankshaft is not fool proof. Time has proven this to be the case. There is an after market crankshaft and prop hub design that solves all of these problems and gives you a very large safety margin with regards to failure of the crankshaft.
#3 On the VW type 1 crankshaft
there are 3 large bearings and one small one. Any guess where the smaller bearing is? It’s the bearing right behind the prop hub.
An area where a bearing with the most force is placed on it is where the smallest bearing is. Does that make sense? The number 4 bearing carries a great deal of the radial prop load. There has been an issue for years with all new VW engine cases where the oiling to this bearing has been severly limited, case in point, my Aerovee engine case, the #4 bearing oil port was completely blocked. I was told by Aerovee that this was not the norm, and my case somehow slipped through their inspection process, want to guess how many others have slipped through ….I know of 8 confirmed
Aerovee cases where the oil to the #4 bearing was either blocked or partially blocked. The only oil my #4 bearing would have gotten was what was splashed onto it by the camshaft gears. In an automobile this is sufficient most of the time
as the #4 bearing only carries a alternator pulley load ….in an aero engine it carries the prop radial loads. This is a big issue,
don’t take this sitting down, if you are building a VW engine, have this checked.
So what does this mean? Well, the #4 bearing will wear very quicly, maybe worn out in say ….75 hours …..this is a guess, but based on a few engines I have been exposed to in the past 4 months it is close, once the bearing is worn past it’s limits the crankshaft is not unsupported and begins to flop around …..(okay, a stretch but done so to illustrate a point)and this adds to the already imperfect situation I described earlier ….now you have an added problem that possibly accelerates
the crankshaft failure. This is
just common sense …..! The whole VW crankshaft design and use of a shrink fit hub on a big stroker VW engine has issues. I guess the question is …if only 1 in 300 fail is it worth doing something about it. What about 1 in 500? I
prefer to prevent it in the first place ….this flying hobby is dangerous enough without the prop
falling off in flight!
This is NOT speculation either, this is actually happening. This is NOT an Aerovee problem ….it’s a VW aero engine problem.
Aerovee has probably the best of the shrink fit assemblies I have seen, but it’s the over-all design of the VW crankshaft and use of a shrink fit prop hub that has it’s limitations.
I spoke of a purpose built prop hub and crankshaft earlier, guess
what, it has a very large #4bearing that goes with the crankshaft. The bearing surface is almost 1.5 inches wide and has an oil seal that is similar to the oil seal at the flwheel end of the engine. The whole crankshaft and hub package gives you a very large safety margin for crankshaft failures, plus you can’t make a mistake putting this system together that will get you in trouble, if you can tighten a bolt, install a cotter pit add some loctite …then you can put this system in your engine. A small amount of machine work is required of the engine case for the larger #4 bearing, the seller will even do that for you …for a small fee.
Let’s recap; the failures of the crankshaft with shrink fit prop hubs comes from a single or combination of these following.
a) Crack forming within the crankshaft, between the keyway slot and the threaded hole down the center of the crankshaft.
b) Shrink fit hub not installed correctly.
c) Propeller balance issue or tracking problem.
d) the #4 bearing failing due to some issue with lubrication.
e) a prop strike in the past,
this can initiate the cracking process.
I noticed you mentioned driving your prop from the flwheel end of the VW …..that is the best way
known, but the Force One crankshaft and hub are the next best thing! It’s so simple I cannot believe it was not invented years ago …….it gives you confidence just by looking at it.
There is another advantage to the Force One Prop Hub system, you can easily remove the prop hub …it uses a taper fit to grip the crankshaft, this is a very strong
old school way of driving devices
and it works well, and this conncetion will yield if the connection is over loaded ….as in
a prop strike …and NOT break the crankshaft. It might slip …but should get you home …..
I want to make it clear that I am in no way bad mouthing Aerovee over
this, even though they are taking it that way …..they have been very easy to work with and I like their product …..I had a concern with their crankshaft and hub, they told me NOT to worry about it …it was reliable, that was NOT the answer I was looking for, so I made a change to improve the only issue I had with my Aerovee…..because I prefer bigger saftey margins when and where possible, and this was an easy way to address a known problem.
It was a simple upgrade to my Aerovee, and it made flying this engine safer, there is no down-side to this modification, it’s a win-win improvement. Okay, $900 is sort of a down side, but it only stings for s few minutes!!!!!
All of the other Aerovee parts bolts right into place. It would really say something if Aerovee would at least offer this upgrade as an option ……give the builder
the added safety margin, to me that
would really say something about the seller ……that would impresse me!
Since I was quoted here …..I wanted to make sure my side was fully understood. The Aero VW is a nice engine, and reliable, but as we move forward we need to embrace improvements to old ideas. If you understand the engines limitations you can find ways to work around them. There is no reason I should not get 1500+ hours out of this engine.
For the record I would have driven
my engine from the flywheel end, I always did it that way in my Gyroplane days with VW’s, but the Sonex has a small engine compartment ….I did not want the extra engineering challenge, I wanted this aircraft project to remain simple for a change!
Thank you,
Les
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And more food for thought this one from Jim Showker over at the Yahoo Aerovee forum group.
Hi all,
Well, I may regret this, cause I just might want to build a Xenos
someday, but here goes. . .
On the subject of the crankshaft and Aerovee engines in general. The
Great Plains crank setup adds a much larger bearing at the end of the
crankshaft where the prop hub mounts, replacing the small standard #4
bearing. The VW was never designed to handle the diverse loads of a
prop. There are pulling loads of several hundred pounds, and side loads
that oscillate due to the inevitable out of balance condition of the
prop. Adding a much bigger bearing at the prop end of the crankshaft
can only be a good thing.
The problem with shrink fitting the prop hub on the shaft is one of
repeatability. When you remove it, it can tear up the hub and the
crankshaft. Every time it is removed and put back on it is less
secure. So the problem really comes when you want to rebuild the engine.
Now this is not to say that the Aerovee setup won't work. It does work
and has a history of doing so.
My interest in all this comes from a friend who is building a Sonex and
also ordered the Aerovee engine and has assembled it. I read over his
manual for the motor before he started on it and was really impressed.
However, when he started assembling it, I was not so impressed. Let me
tell you why.
A "VW engine" as we call it and as used in an experimental airplane, has
almost no VW parts in it. In addition, we tend to increase the
displacement and power output, to levels never even dreamed of by
Ferdinand Porsche, the original designer. All these internal engine
parts come from different aftermarket suppliers. It is possible, after
many year of development of these parts, to assemble a hi power, hi
displacement engine that is reliable. The problem of course is making
these parts fit together properly. When the crank comes from one
company, the pistons/cyls from another, the cam from yet another, to say
nothing of the machining of the crankcase and increasing the size of the
bolts and studs, etc, how can you know all these parts will work
together? Who makes sure all the parts fit with each other? Why, the
builder, of course, and that has been where the real skill comes in
building a hi performance, hi displacement VW.
Now when I read the Aerovee manual, I thought, "Great, Aerovee has
brought all these parts together and makes sure they all fit and work
together." I further assumed that the parts are either balanced or
checked for balance in the kit.
Well, as soon as my friend started assembling his engine, he called me
to say that the parts don't fit, The crank and rods hit the cam and
crankcase, etc. etc. Well. . . . this is the standard type of problem
you get when you buy a bunch of VW parts and try to put them together.
I went up to his place and looked and sure enough, it was just a bunch
of VW parts from aftermarket suppliers, that have not been made ready
for assembly, and at a hefty price premium for the Aerovee kit. They
even charged an incredible price to press fit the prop hub on the
crankshaft, a job any competent crank shop would charge less than $100 for.
So then, my friend got a gram scale and we weighed some of the parts.
The pistons and rods were not balanced. Which also made me suspicious
of the crank. I called the guy at Aerovee for my friend, and he said
"Yeah, the parts are balanced, we get them that way from our
suppliers." He also told me the standard mantra, "These engines are
such low speed, that balance doesn't make any difference, anyway."
Balancing parts means machining away material from the heavy weight
parts, or, in the case of the crankshaft drilling holes to remove
material from counterweights or webbing so as to achieve centrifugal
balance. None of my friends parts had been machined in any way to
achieve balance. The pistons were not too bad, all of them being within
about 5 grams of each other. The rods were about as close except for
one which was way off, I don't remember how much. I consider 0.5 gram
as the most allowable difference on a 3600 rpm engine. The factory spec
at VW was + or - 5 grams for pistons and rods.
Now, here's the problem. If you build an engine with the pistons
within, let's say, + or - 5 grams, and everything else is perfect, it
will be a reasonably smooth engine. Balancing the pistons would make a
difference, but not a huge difference. BUT, lets say you have a heavy
piston, and that just happens to end up on a heavy rod, and here's the
worst case, on the opposite side of the engine you happen to end up with
the light rod and the light piston. You could have an imbalance of 20
grams across those two cylinders. (and that's not even taking the crank
into consideration) Such an engine will idle with a lope, and sound
like it's got a carburetion or ignition problem. these forces are not
linear, either, they are square law forces. double the amount of
imbalance in grams, and the vibrational forces increase by a factor of
4. So, 20 grams of imbalance would have 16 times the vibrational
forces of just 5 grams.
Now, what I've described here is called "tolerance stack up". It is
well known to engine builders, and is acceptable in a production engine
that might be in a car. It's not acceptable to me for an engine going
in a plane. Especially when you spend $7k for a kit. If you're
spending that kind of money, a couple hundred bucks extra to have it
balanced, (and I would also spend a few hundred on some other things) is
a no brainer for me. i can't understand why the factory would not do
this, or at least recommend it.
I guess that guy at Aerovee had never experienced the difference between
a balanced engine and one that wasn't. I built over 40 of these
engines, about a 1/3 of them Porsches back in the 70's and 80's. (also
a couple corvairs) Can you remember riding in a VW way back when, and
the rear engine sounded and felt like a "rock crusher" when wound up?
That's what a reviewer in a car magazine called the VW motor back in the
60's. Balance that motor and it sounded and felt completely different.
Like a finely tuned watch that would smoothly rev up and made noticeably
more power. If you turn your motor up to 3600 rpm, you are spinning it
faster than it ever did in a VW car.
So, Aerovee doesn't even check the balance of the parts. My friend had
one rod that was way off from the others. It takes a sophisticated
setup to balance a rod, as each end is balanced separately, but in just
weighing total weight, it was way off. If you are an engine builder,
and you've built a number of engines, you learn one cardinal rule. That
is "Trust, but verify" In other words, trust your suppliers and
machinists, but check their work. They can make mistakes, just like
anyone else.
So, here's what it looks like to me. Aerovee just buys a bunch of parts
to build an engine, never even touches them, and bundles the parts with
a few machined parts that make the motor work with an airplane, at a
hefty price. And on top of it, charges how much to put a prop hub on
the crank?
Sorry, but I am not impressed. And then to read this forum and others
where owners talk about the problems they are having. . . . well, like
I said, I am not impressed.
Now, this is not an endorsement for Great Plains. They say they have
the same standards for balance as the VW factory did, + or - 5 grams for
pistons and rods, and they likewise trust the crank maker to balance
it. As you can imagine, I like to trust, but verify.
Hope this doesn't get me banned from the list. Or black balled or
something. I guess it's just another exercise in free speech.
:o)
Jim
So there you have it.Still undecided? I am but there be lots of time yet :)
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This is impressive
Re: [sonextalk] Revmaster/Great Plains
I think you are making a bad mistake I flew the AeroVee for 740 hours and made
4 trips from Florida to Oskosh with it and never a problem.
I had a freind that had a Revmaster and it was lots of trouble. I don't have any
erperance wih the Great Plains but I can assure you the AeroVee is a great
little engine
I later put in a 3300 because I wanted a Hot Rod and it is.
Tony Lewis
N447XL
740 hours on AeroVee and over 450 hours on a 3300
Sonex #447
First Flight: January 4th, 2003
Engine: Jabiru 3300
Gear: Tricycle
Controls: Dual
Builder: J. Tony Lewis
Current Owner: J. Tony Lewis
Email: jlewis99@tampabay.rr.com
Phone: N/A
Location: Winter Haven, FL United States (Map)
EAA Technical Counselor: No
EAA Flight Advisor: No
Originally AeroVee Powered. Converted to Jabiru 3300 after over 700 hours of AeroVee flights!
From: aerovee@yahoogroups.com [mailto:aerovee@yahoogroups.com] On Behalf Of
Windsor
Sent: Saturday, August 13, 2011 3:33 PM
To: aerovee@yahoogroups.com
Subject: [aerovee] prop/hub saga
Hi guys.I am building an Onex and am undecided about the engine I will use.
does anyone have a figure as to how many prop hub failures there have been
on the aerovee 2.1 installation.I am not interested on the earlier version
2.0.At this point I am not concerned about the why eg; Builder error or oil
starvation.Just a number. Is there an faa accident site that can access this
info whereby you can plug aerovee into the search and come up with all the
aerovee engine data?
Thanks in advance and please don't take this as a slight to aerovee.I am
simply trying to distinguish fact from fiction.
Mike.I a
Well It caused a slight commotion and Sonex jumped in with this reply in both aerovee and sonextalk
What i have highlighted in red is the answer I have been looking for ,I think?.In essense Sonex is stating categorically that there has Never Been A failure of an aerovee crankshaft assembly.
From: Sonex Aircraft, LLC <jeremy@...>
Subject: [sonextalk] AeroVee Crank Shaft and Prop Hub vs. the Competition.
To: ""sonextalk@yahoogroups.com"" <sonextalk@yahoogroups.com>,
""aerovee@yahoogroups.com"" <aerovee@yahoogroups.com>
Date: Tuesday, August 16, 2011, 6:14 PM
Hello again AeroVee and Sonextalk Groups-
Sonex Aircraft will continue to study the recent crank shaft break, which
has been quoted on these lists going on 2 weeks now...again providing the
incorrect perception that this is a widespread problem.
We hope that our competitors who have long claimed to have a superior
product will reveal the problems and failures that they have had with their
crankshaft assembly. It should be further noted that the AeroVee continues
to dominate the VW Conversion Market, so there are simply many, many more in
the field...it's a much larger sampling to take data from.
I personally believe that those that have a preference for a "Force-One"
type prop hub do not understand the shrink fit design of the AeroVee and
probably have not even seen it. I would encourage those who have concerns to
have a look at the components that comprise the installation (and the entire
AeroVee Conversion for that matter) which will result in an understanding of
the strength, simplicity, and elegance in form and function. We
always have a forum and Booth at AirVenture and have an entire presentation
on Engine Development as part of the Sonex Workshop.
As was already pointed out on these lists, Aircraft engines of all types,
including type certified engines have had mechanical failures of all types.
None of us that design, build, test, and sell engines and engine conversions
want to see a single failure, but they happen. Our job is to learn what
caused them and, when appropriate, issue Service Notices and/or Product
Changes if we feel they are warranted.
It is also the owner/operator's responsibility to accurately and truthfully
report all circumstances surrounding an incident so a proper and well
informed investigation can be made, and facts, not speculation, reported to
the fleet owner's. Too often pride or the desire to blame others prevents
this from happening.
As stated before on these lists, we continue to fly 8 of our AeroVee Engines
in factory Sonex aircraft and have been flying successfully behind our same
basic shrink-fit hub design for 11 years. 5 of the factory installations are
the AeroVee 2180/2.0 design and 3 of the factory installations are the
newest AeroVee 2.1. Our competitors in the vw conversion business do not
maintain a fleet of test engines and do not regularly fly behind their own
engines.
The most common concern we heard from customers was with their ability to
successfully achieve the shink-fit installation, which we answered by
offering an "Assembled Crank Shaft" on the AeroVee 2.1:
http://www.aeroconversions.com/products/aerovee/
We appreciate the efforts of those who continue to root out the
misinformation that is all too readily spread amongst egroups, builder
Forums, and fly-ins and builder gatherings.. Sonex agrees that sticking to
facts is always the best course of action when discussing any company's
products.
There are 2 versions of the AeroVee Crankshaft Assembly:
The AeroVee 2180/2.0 version was sold from 2001 through 2008
The AeroVee 2.1 version with a custom crankshaft and hub has been
shipping since 2008.
To date, there has never been a failure of either a factory-assembled
AeroVee Crankshaft (2180 , 2.0 or 2.1) or of any 2.1 AeroVee Crankshaft
Assembly including all customer-assembled units.
As always, please feel free to contact Betty, John, Jeremy, Kerry, Mark,
Heather , Jason, or Stephanie at the numbers or e-mail below
with any questions or Comments.
After spending a lot of time and search effort on this issue I now consider it a non-issue.I am satisfied that Flying behind an Aerovee is no more dangerous than flying behind the competition.In the few accident reports I could gleen ,only one admonished Sonex for not giving instruction how to remove the hub from the crankshaft and what must be done/checked before re-attaching it.Sonex claims that they have rectified this .
So bottom line if your concerned about it have Sonex attach the hub for you,and fly behind it with peace of mind.It's what I intend if I decide to purchace the Aerovee
Mike
PS; I found this and decided to add it post mortem :)
http://ereksonfamily.org/sonex/aerovee-engine/vw-prop-hub-on-aerovee/
or read it here
VW prop hub on AeroveeThe issue has arisen many times about Prop Hubs on VW engines and the lack of bearing surface.
This post occurred on one of the Sonex yahoo groups:
VW Cranks (Was Re: Sonex Incident – 9/29/2007)
Frank,
I have sat back too and read this thread on the
VW problems ….part of me just said to keep
quiet …..but the other parts says to share what
you know …..I am no expert but 20+ years of aero
vw use has taught me some stuff ……so here goes;
You hit the nail on the head here. However the VW
with a stock crank and shrink-fit hub works very
well on engines up to 1915cc …..I know because
I have flown behind them for 20+ years, the added
torque of the 2180 increases the risk of failure,
and many of the guys I call experts agree.
I have an Aerovee 2180, I like the looks of it and
I like the package as a whole. When I bought mine
I knew I was going to discard the AeroVee crankshaft
and shrink-fit prop hub!
I immediately sent the block to Steve at Great Plains
and had the block machined for the Force One Prop Hub,
I also purchased his aircraft purpose-built 82mm forged SCAT
crankshaft. It was designed to have the extra
metal in the area of failure, and they have never
had one fail to date. They use it on 2300cc VW’s.
There is nothing wrong with the VW, but building a
2180cc engine begins to exceed the strength of the base
engine it’s built from. My last 2180cc VW engine had over
1400 hours on it when I sold it ….and it was built by me
from parts I purchased from CB Peformance with the
exception of the crankshaft and prop hub, these came
from GreatPlains!
All my VW engined planes to date were single seat aircraft,
but my SONEX will carry passengers (wife and children) so I
spent the extra money to insure my engine stays together.
Nothing against Sonex / Aerovee, but the VW engine was NOT
designed by them, so they are NOT the last word on anything
VW. They put together a nice package and it’s a really
nice engine, but they know of the possible issues with
the VW crankshaft design with a shrink-fit prop hub, they
are aware ….that’s why they stress correct prop hub installation,
the Aerovee is not their first use of the aero-vw engine!
Even when installed correctly as per Aerovee, the design is
marginal …NOT bad …but marginal! There is room for error
that can cause failure. One of the established installation
procedures and setup is the have the front 2 cylinders at
TDC ….(pistons out towards the cylinder heads) and install
the prop in a horizontal postion, plus insure the prop
tacks true. This will increase the survival rate of the
prop hub. Also it has been found that keeping the prop
length 55″ and below is safer. These are just common VW
engine practices by others ……the big practice is to
use wooden props only! This one is obvious but I felt it
needed said as not everyone here will buy a prop from Sonex.
While on the subject there is a SERVICE Bulletin on
all VW Supercases, the #4 bearing oil feed has been found
to be improperly sized / installed on 1 out of every 4 new
cases. The #4 bearing is the small bearing behind the
prop hub …..this has not been attributed to the prop
hub / crankshaft failures but needs resolved for long
engine service. Contact Steve Bennett at GreatPlains if you
want a better explanation.
It’s a simple fix, can be done with the engine in the plane. You
drill out an oil plug, internally remove the restrictor
plug and install a screw in plug. Steve at Great Plains
reminded me of this …..and “my Aerovee block” was one of the
defective ones. He fixed it while he had it in his shop.
While I love my Sonex and the Aerovee, it’s NOT a perfect
powerplant as received from Sonex. The Aerovee 2180 is just
assembled from off-the-shelf components internally. The
Aerovee specific stuff is outside of the engine, all the
pretty red anodized parts, the Aerovee Carb and there sort
of neat ignition system …….all nice stuff!
I have flown behind VW engines for a long time, and I have
lost a prop hub on an early Monnett engine (before Aerovee)!
I don’t plan to loose another ….of anybodys manufacture!!!
I don’t worry about warranty, there really is none once
the engine is flying ….I am currently NOT using the AeroCarb
either, I use an EFI system from SDS (Simple Digital Systems).
I don’t have cooling problems and have never had any, the
EFI precisely controls the mixture …..it starts on the
second rotation of the prop, even at 20 degrees …..I have
run it on Ethanol …just a programming change to switch
between fuels. Yes, EFI is more complicated, yes it has an
electric fuel pump ..(I use redundant pairs)…but it is as
reliable as anything out there, I have been using this system on
some other aero engines as well as the VW for 4 years …..
the SDS system is aircraft quality …and is not cheap, but
I prefer EFI!
Not going to argue any of this, just sharing what I know
on the subject! You have a question I’ll be glad to answer
it ….just too old to debate stuff that I have learned the
hard way!
My 2 cents!
Les
Sonex #1094
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Generated this response:
Hello again Sonextalk Group-
As promised, we wanted to address some of the comments made the past couple
of days on the AeroVee Design. We feel these comments need to be responded
to, especially those that are misleading and provide limited background
information. We provided our responses after the quoted text excerpts from
these postings.
>You hit the nail on the head here. However the VW
>with a stock crank and shrink-fit hub works very
>well on engines up to 1915cc …..I know because
>I have flown behind them for 20+ years, the added
>torque of the 2180 increases the risk of failure,
>and many of the guys I call experts agree.
=As addressed in the past, there is very little “stock” about an AeroVee
Engine Core. Nearly 100% of the component parts are aftermarket component
parts. The Crankshaft is forged -and Nitrtrided- 4340 Steel. A common
misunderstanding (even from those that claim to be vw experts) are the real
loads that need to be addressed in designing conversion components for the
VW Core. The Modern AeroVee Conversion exists today because of the many
shortcomings of the existing conversions that were offered by other
manufacturers in the late 1990′s. The AeroVee has been challenged in
rigorous flight testing under the highest stress flight
situations…including Aerobatics. Most pilots do not engage in this kind of
flying. We insist on testing our installations in these most rigorous
conditions.
>All my VW engined planes to date were single seat aircraft,
>but my SONEX will carry passengers (wife and children) so I
>spent the extra money to insure my engine stays together.
=There have been many thousands of rides given in AeroVee Powered Aircraft
of all types. There is no need to speculate that the AeroVee Prop Hub design
somehow makes the aircraft unsafe. This is an irresponsible comment and an
irrational concern not based on fact, but purely speculation and opinion. An
AeroVee Shrink Fit Prop Hub installed and maintained properly yields the
highest strength and simplest installation on any VW Engine Conversion.
>While on the subject there is a SERVICE Bulletin on
>all VW Supercases, the #4 bearing oil feed has been found
>to be improperly sized / installed on 1 out of every 4 new
>cases.
=This Service Bulletin on the #4 Bearing is many years old. We have not
encountered any cases in the many hundreds that have come through our
factory that have this issue. If this was a true service issue, there would
be many vw vehicles stuck on the side of the road that you would be passing
on a routine basis.
>While I love my Sonex and the Aerovee, it’s NOT a perfect
>powerplant as received from Sonex.
=There is no manufactured product or Aircraft Conversion that does represent
the perfect powerplant or the perfect product. However, the great success of
the AeroVee can be attributed to its combination of simplicity,
reliability,and light weight in an extremely robust and well proven package.
It’s the pursuit of perfection that most distinctly separates
AeroConversions and Sonex products from the competition. We promise that as
opportunities present themselves, we will continue to improve and expand
our product lines as any reputable and successful aircraft manufacturer
would.
> about warranty, there really is none once
>the engine is flying
=I’m not sure where the information about a warranty expiring once an
AeroVee Flies was obtained. This is completely false. If a part is found to
be defective in an AeroVee whether it is flying or not, there most
certainly is warranty coverage. Obviously, if you modify the component parts
or if the builder is found to be the one that caused the problem, then the
replacement cost on parts are your responsibility.
Spending $1500+ on a Fuel Injection System for your AeroVee makes absolutely
no sense to us whatsoever….especially if it’s put on a Sonex, Waiex, or
Xenos set up for Gravity Feed. We have many thousands of hours flying with a
smooth running, low fuel burn, no carb heat, no mixture problems and no
overheating using the standard AeroCarb. For our factory aircraft located in
Oshkosh, WI we make two carb adjustments per year. One approx. 1/4 turn
needle adjustment in the spring as it warms up and one 1/4 turn needle
adjustment in the fall as the air becomes cooler and denser… without the
complication of vapor-lock prone fuel pumps, which do have a tendency to
fail even if they are run in a redundant configuration. Gravity hasn’t
failed us yet…it if does, we certainly have bigger things to worry about.
The reason the AeroVee is sold as a kit is that we back the system as a
whole. If a builder makes modifications to the engine (i.e. Prop hub,
induction system, etc), unfortunately the AeroVee Name is still on the
engine package. If and when an individual has a failure and these
modifications are not revealed on an accident report, then its the AeroVee
Name that loses credibility. This is the same reason that AeroVee
Components are not sold individually to be used on hodge-podge engine
conversions usually done by individuals who have no flight or design
experience with auto conversion engines.
We look forward to continuing to hear flight success stories and supporting
all of our customers in completing their dreams of building and flying their
own aircraft.
As always, please feel free to contact Betty, Heather, Mark, Kerry, John,
Jason, Kristy or myself at the numbers or e-mail below with questions or
comments.
Regards,
-jeremy
–
Jeremy Monnett
CEO
Sonex Aircraft, LLC
www.sonexaircraft.com
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Notice carefully the selective quoting of the original post, and the essential failure to address the key issue, the reliability of the shrink fit hub, and the exactitude it requires.
R.S. Hoover , known to a generation of Volkswagen enthusiasts as Veeduber@, has put together this little history of putting props on VW engines. The Aerovee hub is, in Mr. Hoover’s lexicon, Thick (or heavy) Walled Shrink Fit hub. I believe it is long, per his example figure 9. Mr Hoover suggests some possible failure modes. I’d like to suggest another.
Using this calculator, and a lot of assumptions and estimates, I found that the allowable fit tolerance between the nose of the crank and the ID of the hub was uncomfortably small. The new tolerance on the nose of the crank, from VW back in the day was about 9 ten thousandths of an inch, I.E. the #4 bearing journal could be as small as 1.5739 inch or as big as 1.5748. For the shrink fit to work, the frictional forces between the hub and the shaft have to be high enough to withstand the torque to be transmitted, AND the hoop stresses induced have to be low enough to keep the hub from failing due to fatique. Again, using fishy dimensions I SWAG’d from pictures of the Aerovee hub, known dimensions of VW cranks, allowable stresses for common grades of steel, I found that the allowable tolerance on the fit was LESS than the tolerance on the crank itself. And aftermarket VW parts are not known for holding close tolerances.
I encourage others, particularly someone with an AeroVee hub handy to measure to an accuracy of .0001″, to work through the calculations themselves, and report the results to the rest of us. An undergraduate education in mechanical engineering MAY help in deciphering the calculations, but those not burdened by such can probably puzzle their way through it
To wrap it up, I believe the AeroVee long and thick shrink fit hub CAN work IF the crank and the hub are measured and matched to a high degree of accuracy. There are at least 100 AeroVees that ARE flying, some with hundreds of hours. I’ve chosen to drive my prop from the flywheel end of my engine. It’s not flown yet, and there are very few converted VW engines of this configuration that have.
Labels: aviation
posted by flybynightkarmarepair @ 8:24 AM 2 Comments
2 Comments:
At 12:58 PM , Blogger Soloflyer62 said…
Hello,
Since the original Post was mine I wanted to add a few points that need to be clarified and may NOT have been brought out in what you
posted. I have a mechanical engineering degree …so math is something I can do easily.
What this all comes down to is how much margin for failure are you comfortable with. If you prefer, what odds of failure can you live with? 1 in 50? 1 in 500? 1 in 10,000? I want the max safety margin I can afford, but that’s
just me.
First, it’s NOT the prop hub that fails. It’s the crankshaft, so let’s call it what it is, a “crankshaft failure”.
The shrink fit hub is NOT new or an Aerovee design, it has been used on airplanes for a many many years …..the shrink fit hub is just NOT a new item. There have been many attempts to improve on the simple concept, but it is still basically the same as it was 20 years ago.
Again, the reason for most failures has NOT been the actual failure of the prop hub, but the failure is the stock VW crankshaft design and there are several key issues that all contribute to a failure and ultimate separation of the hub / prop from the engine.
#1 The prop hub only slides onto the crankshaft just less than 1 inch. That creates a great deal of mass when the prop is installed hanging out in front of the crankshaft unsupported. Think about it for a minute ….!
#2 The prop hub end of the stock VW crankshaft has a rather large threaded hole bored down the middle of it to retain a bolt for a pulley on the VW engine in the automotive configuration. This hole
goes fairly deep into the crankshaft ….on the outside of the crankshaft (same end) is a keyway groove cut into the OD of the crankshaft …..there is an area of this end of the crankshaft where the threaded hole down the center and the keyway groove almost meet, There is approx 1/8th
of an inch of crankshaft metal between the keyway groove and the threaded hole. The prop hub is slipped right over crankshaft but
does NOT cover this weakened area,
it basically stops right even with this weakened area of the crankshaft. The area I am talking about is just in front of the crankshaft oil slinger disc ….when you install the prop hub you press it right up against the oil slinger disc …..a nice
clean place to break is provided, and that is where they break,
approx. 1/8th of an inch in front of the oil slinger. The crankshaft is almost designed to break here, but this is by accident, NOT intentional, it’s just an automotive part not designed to carry this kind of load. The good
thing is that the metal the crankshaft is made from is very rugged …and you have to create
a situation for it to crack …
and we do just that …read on.
If all things are perfect, hub pressed on correctly, propeller perfectly balanced and tracking true ….the #4 bearing getting good oil for cooling and lubrication, most of the time there
is no issue, everything works in harmony, but …..if there is a flaw in the crankshaft casting, the hub is not installed perfectly,
the propeller is NOT pefectly balanced and tracking true, the #4 bearing is not getting adequate lubrication…. a slight
vibration starts to fatigue the
crankshaft …a crack forms in the area described earlier between the keyway slot and the threaded hole bored down the center of the crankshaft …..once the crack grows long enough to bridge the area between the keyway slot and the threaded crankshaft hole …the crank fails
and the prop hub comes off in flight.
It is believed that bigger engines have accelerated this failure somewhat due to the increased torque and strength of the firing pulses of the engine …and failures have or will increased in numbers. 20 years ago an 1835 cc VW was big, today the 2180cc and 2300cc VW’s are common place. We have not mentioned the junk cast crankshafts that once flooded the market ….we are just talking about the current design of the market’s shrink fit prop hub and a stock VW crankshaft design.
Some VW prop hub crank failures don’t happen until the engine has several hundred hours on them. So
there are a large number of VW based engines that have not reached this point yet ……so don’t think it won’t or cannot happen ….time will tell. I prefer
to be pro-active, if there is a problem …it will happen to me, I am one of those guys ….so I acted, but when it comes to safety I have no problem spending some extra money.
I mentioned a safety margin in my original post, it is here that I feel there is room for improvement.
If everything is not exactly perfect with the crankshaft from
the manufacturer, if the prop hub
is not fully heated and installed within the first try at installing it, if the prop is not perfectly balanced and running true ….the risk of failure of the crankshaft is increased many times over ……and we all know that these are experimental aircraft and engines we are talking about …..most folks do not have the nice shop equipment, shop ovens, IR temp guns, hydraulic presses ….most are do-it-yourself folks with often just common hand tools …so the design needs to be goof proof,
with a large margin for safety, in case something less than ideal is
encountered during the building process…and heaven forbid goes undetected. Maybe the engine kit seller should build this assembly for the kit builder since it’s so critical ….that has got to be an improvement, right? In my simple mind, if a step or process has serious consequences, steps should be taken to insure success and safety, and the old shrink fit prop hub on a VW crankshaft of stock dimensions has possible failure written all over it, it did 20 years ago …and even thought it’s better today than it was it’s still an issue. Just a simple comment but my local FAA rep hates VW engines with shrink fit hubs ….the guy has seen plenty of props come off ….enough said!
The shrink fit hub on a standard dimension VW crankshaft is not fool proof. Time has proven this to be the case. There is an after market crankshaft and prop hub design that solves all of these problems and gives you a very large safety margin with regards to failure of the crankshaft.
#3 On the VW type 1 crankshaft
there are 3 large bearings and one small one. Any guess where the smaller bearing is? It’s the bearing right behind the prop hub.
An area where a bearing with the most force is placed on it is where the smallest bearing is. Does that make sense? The number 4 bearing carries a great deal of the radial prop load. There has been an issue for years with all new VW engine cases where the oiling to this bearing has been severly limited, case in point, my Aerovee engine case, the #4 bearing oil port was completely blocked. I was told by Aerovee that this was not the norm, and my case somehow slipped through their inspection process, want to guess how many others have slipped through ….I know of 8 confirmed
Aerovee cases where the oil to the #4 bearing was either blocked or partially blocked. The only oil my #4 bearing would have gotten was what was splashed onto it by the camshaft gears. In an automobile this is sufficient most of the time
as the #4 bearing only carries a alternator pulley load ….in an aero engine it carries the prop radial loads. This is a big issue,
don’t take this sitting down, if you are building a VW engine, have this checked.
So what does this mean? Well, the #4 bearing will wear very quicly, maybe worn out in say ….75 hours …..this is a guess, but based on a few engines I have been exposed to in the past 4 months it is close, once the bearing is worn past it’s limits the crankshaft is not unsupported and begins to flop around …..(okay, a stretch but done so to illustrate a point)and this adds to the already imperfect situation I described earlier ….now you have an added problem that possibly accelerates
the crankshaft failure. This is
just common sense …..! The whole VW crankshaft design and use of a shrink fit hub on a big stroker VW engine has issues. I guess the question is …if only 1 in 300 fail is it worth doing something about it. What about 1 in 500? I
prefer to prevent it in the first place ….this flying hobby is dangerous enough without the prop
falling off in flight!
This is NOT speculation either, this is actually happening. This is NOT an Aerovee problem ….it’s a VW aero engine problem.
Aerovee has probably the best of the shrink fit assemblies I have seen, but it’s the over-all design of the VW crankshaft and use of a shrink fit prop hub that has it’s limitations.
I spoke of a purpose built prop hub and crankshaft earlier, guess
what, it has a very large #4bearing that goes with the crankshaft. The bearing surface is almost 1.5 inches wide and has an oil seal that is similar to the oil seal at the flwheel end of the engine. The whole crankshaft and hub package gives you a very large safety margin for crankshaft failures, plus you can’t make a mistake putting this system together that will get you in trouble, if you can tighten a bolt, install a cotter pit add some loctite …then you can put this system in your engine. A small amount of machine work is required of the engine case for the larger #4 bearing, the seller will even do that for you …for a small fee.
Let’s recap; the failures of the crankshaft with shrink fit prop hubs comes from a single or combination of these following.
a) Crack forming within the crankshaft, between the keyway slot and the threaded hole down the center of the crankshaft.
b) Shrink fit hub not installed correctly.
c) Propeller balance issue or tracking problem.
d) the #4 bearing failing due to some issue with lubrication.
e) a prop strike in the past,
this can initiate the cracking process.
I noticed you mentioned driving your prop from the flwheel end of the VW …..that is the best way
known, but the Force One crankshaft and hub are the next best thing! It’s so simple I cannot believe it was not invented years ago …….it gives you confidence just by looking at it.
There is another advantage to the Force One Prop Hub system, you can easily remove the prop hub …it uses a taper fit to grip the crankshaft, this is a very strong
old school way of driving devices
and it works well, and this conncetion will yield if the connection is over loaded ….as in
a prop strike …and NOT break the crankshaft. It might slip …but should get you home …..
I want to make it clear that I am in no way bad mouthing Aerovee over
this, even though they are taking it that way …..they have been very easy to work with and I like their product …..I had a concern with their crankshaft and hub, they told me NOT to worry about it …it was reliable, that was NOT the answer I was looking for, so I made a change to improve the only issue I had with my Aerovee…..because I prefer bigger saftey margins when and where possible, and this was an easy way to address a known problem.
It was a simple upgrade to my Aerovee, and it made flying this engine safer, there is no down-side to this modification, it’s a win-win improvement. Okay, $900 is sort of a down side, but it only stings for s few minutes!!!!!
All of the other Aerovee parts bolts right into place. It would really say something if Aerovee would at least offer this upgrade as an option ……give the builder
the added safety margin, to me that
would really say something about the seller ……that would impresse me!
Since I was quoted here …..I wanted to make sure my side was fully understood. The Aero VW is a nice engine, and reliable, but as we move forward we need to embrace improvements to old ideas. If you understand the engines limitations you can find ways to work around them. There is no reason I should not get 1500+ hours out of this engine.
For the record I would have driven
my engine from the flywheel end, I always did it that way in my Gyroplane days with VW’s, but the Sonex has a small engine compartment ….I did not want the extra engineering challenge, I wanted this aircraft project to remain simple for a change!
Thank you,
Les
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And more food for thought this one from Jim Showker over at the Yahoo Aerovee forum group.
Hi all,
Well, I may regret this, cause I just might want to build a Xenos
someday, but here goes. . .
On the subject of the crankshaft and Aerovee engines in general. The
Great Plains crank setup adds a much larger bearing at the end of the
crankshaft where the prop hub mounts, replacing the small standard #4
bearing. The VW was never designed to handle the diverse loads of a
prop. There are pulling loads of several hundred pounds, and side loads
that oscillate due to the inevitable out of balance condition of the
prop. Adding a much bigger bearing at the prop end of the crankshaft
can only be a good thing.
The problem with shrink fitting the prop hub on the shaft is one of
repeatability. When you remove it, it can tear up the hub and the
crankshaft. Every time it is removed and put back on it is less
secure. So the problem really comes when you want to rebuild the engine.
Now this is not to say that the Aerovee setup won't work. It does work
and has a history of doing so.
My interest in all this comes from a friend who is building a Sonex and
also ordered the Aerovee engine and has assembled it. I read over his
manual for the motor before he started on it and was really impressed.
However, when he started assembling it, I was not so impressed. Let me
tell you why.
A "VW engine" as we call it and as used in an experimental airplane, has
almost no VW parts in it. In addition, we tend to increase the
displacement and power output, to levels never even dreamed of by
Ferdinand Porsche, the original designer. All these internal engine
parts come from different aftermarket suppliers. It is possible, after
many year of development of these parts, to assemble a hi power, hi
displacement engine that is reliable. The problem of course is making
these parts fit together properly. When the crank comes from one
company, the pistons/cyls from another, the cam from yet another, to say
nothing of the machining of the crankcase and increasing the size of the
bolts and studs, etc, how can you know all these parts will work
together? Who makes sure all the parts fit with each other? Why, the
builder, of course, and that has been where the real skill comes in
building a hi performance, hi displacement VW.
Now when I read the Aerovee manual, I thought, "Great, Aerovee has
brought all these parts together and makes sure they all fit and work
together." I further assumed that the parts are either balanced or
checked for balance in the kit.
Well, as soon as my friend started assembling his engine, he called me
to say that the parts don't fit, The crank and rods hit the cam and
crankcase, etc. etc. Well. . . . this is the standard type of problem
you get when you buy a bunch of VW parts and try to put them together.
I went up to his place and looked and sure enough, it was just a bunch
of VW parts from aftermarket suppliers, that have not been made ready
for assembly, and at a hefty price premium for the Aerovee kit. They
even charged an incredible price to press fit the prop hub on the
crankshaft, a job any competent crank shop would charge less than $100 for.
So then, my friend got a gram scale and we weighed some of the parts.
The pistons and rods were not balanced. Which also made me suspicious
of the crank. I called the guy at Aerovee for my friend, and he said
"Yeah, the parts are balanced, we get them that way from our
suppliers." He also told me the standard mantra, "These engines are
such low speed, that balance doesn't make any difference, anyway."
Balancing parts means machining away material from the heavy weight
parts, or, in the case of the crankshaft drilling holes to remove
material from counterweights or webbing so as to achieve centrifugal
balance. None of my friends parts had been machined in any way to
achieve balance. The pistons were not too bad, all of them being within
about 5 grams of each other. The rods were about as close except for
one which was way off, I don't remember how much. I consider 0.5 gram
as the most allowable difference on a 3600 rpm engine. The factory spec
at VW was + or - 5 grams for pistons and rods.
Now, here's the problem. If you build an engine with the pistons
within, let's say, + or - 5 grams, and everything else is perfect, it
will be a reasonably smooth engine. Balancing the pistons would make a
difference, but not a huge difference. BUT, lets say you have a heavy
piston, and that just happens to end up on a heavy rod, and here's the
worst case, on the opposite side of the engine you happen to end up with
the light rod and the light piston. You could have an imbalance of 20
grams across those two cylinders. (and that's not even taking the crank
into consideration) Such an engine will idle with a lope, and sound
like it's got a carburetion or ignition problem. these forces are not
linear, either, they are square law forces. double the amount of
imbalance in grams, and the vibrational forces increase by a factor of
4. So, 20 grams of imbalance would have 16 times the vibrational
forces of just 5 grams.
Now, what I've described here is called "tolerance stack up". It is
well known to engine builders, and is acceptable in a production engine
that might be in a car. It's not acceptable to me for an engine going
in a plane. Especially when you spend $7k for a kit. If you're
spending that kind of money, a couple hundred bucks extra to have it
balanced, (and I would also spend a few hundred on some other things) is
a no brainer for me. i can't understand why the factory would not do
this, or at least recommend it.
I guess that guy at Aerovee had never experienced the difference between
a balanced engine and one that wasn't. I built over 40 of these
engines, about a 1/3 of them Porsches back in the 70's and 80's. (also
a couple corvairs) Can you remember riding in a VW way back when, and
the rear engine sounded and felt like a "rock crusher" when wound up?
That's what a reviewer in a car magazine called the VW motor back in the
60's. Balance that motor and it sounded and felt completely different.
Like a finely tuned watch that would smoothly rev up and made noticeably
more power. If you turn your motor up to 3600 rpm, you are spinning it
faster than it ever did in a VW car.
So, Aerovee doesn't even check the balance of the parts. My friend had
one rod that was way off from the others. It takes a sophisticated
setup to balance a rod, as each end is balanced separately, but in just
weighing total weight, it was way off. If you are an engine builder,
and you've built a number of engines, you learn one cardinal rule. That
is "Trust, but verify" In other words, trust your suppliers and
machinists, but check their work. They can make mistakes, just like
anyone else.
So, here's what it looks like to me. Aerovee just buys a bunch of parts
to build an engine, never even touches them, and bundles the parts with
a few machined parts that make the motor work with an airplane, at a
hefty price. And on top of it, charges how much to put a prop hub on
the crank?
Sorry, but I am not impressed. And then to read this forum and others
where owners talk about the problems they are having. . . . well, like
I said, I am not impressed.
Now, this is not an endorsement for Great Plains. They say they have
the same standards for balance as the VW factory did, + or - 5 grams for
pistons and rods, and they likewise trust the crank maker to balance
it. As you can imagine, I like to trust, but verify.
Hope this doesn't get me banned from the list. Or black balled or
something. I guess it's just another exercise in free speech.
:o)
Jim
So there you have it.Still undecided? I am but there be lots of time yet :)
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This is impressive
Re: [sonextalk] Revmaster/Great Plains
I think you are making a bad mistake I flew the AeroVee for 740 hours and made
4 trips from Florida to Oskosh with it and never a problem.
I had a freind that had a Revmaster and it was lots of trouble. I don't have any
erperance wih the Great Plains but I can assure you the AeroVee is a great
little engine
I later put in a 3300 because I wanted a Hot Rod and it is.
Tony Lewis
N447XL
740 hours on AeroVee and over 450 hours on a 3300
Sonex #447
First Flight: January 4th, 2003
Engine: Jabiru 3300
Gear: Tricycle
Controls: Dual
Builder: J. Tony Lewis
Current Owner: J. Tony Lewis
Email: jlewis99@tampabay.rr.com
Phone: N/A
Location: Winter Haven, FL United States (Map)
EAA Technical Counselor: No
EAA Flight Advisor: No
Originally AeroVee Powered. Converted to Jabiru 3300 after over 700 hours of AeroVee flights!