Perhaps this needs to be in its own thread but I believe I can give you some answers but in all fairness my answers might be uncomfortable for some to hear but … here I go again:
Many could understand the whole Corvair argument with Sonex if they read an early thread I posted on the old Sonex Builder’s forum. It is available to read here:
Corvair Engines - The Justification Series - Firewall Forward / Other Engines - SonexPilots.org
In the beginning of that series you can see many actual Sonex builders and how opposed to the idea they were with some seeming to warn of catastrophic results as they felt I was overstepping good sense and the company’s limit on the airframe of a strict FWF weight of 200 lbs. or less. I tried to point out how incorrect they were to make such assumptions. After all the years have passed some have come around to understand and others went away quietly. It’s OK as I hold no animosity to anyone.
That series was written (by permission of the moderators) to answer John Monnets questions when he blew up an earlier thread:
SonexBuilders.net View topic - Corvair - General Info
To answer how Sonex support could benefit Corvair users you would have to be aware of the result that came about by the company doing quite the opposite with a vengeance at times (as seen above in some of John’s comments).
Let me first say that Mark is not at fault here as he did not own the company at that time and has since set a few things straight.
The warning from Sonex for many years was that the FWF weight was a strict number of 200 lbs. or less. They never said why that was a rule so the assumption was that it was a structural issue. Many believed that and one builder even put out his own analysis that showed that Sonex would live a short life with 250 lbs. on the nose. None of that was true as the empirical evidence was overwhelming. I promised not to reveal sources but an engineering friend that is employed for a high level aircraft builder did some software analysis (using some excellent company tools) of the Sonex airframe and Corvair FWF and the results showed no issues at 250 lbs. FWF @ 6gs. I don’t say this for anyone to take as gospel or permission but just to reiterate the findings that I had. There were other sources used to confirm what appeared to be true but I was very careful in my research and deliberations as to a Corvair on a Sonex.
Mark later confirmed in the comment section of a video made by Experimental Aircraft Channel that the the limit was a C/G & W&B issue and not a structural one:
100HP+ Good News for Heavy Pilots! Gross Weight Increase at Sonex Aircraft
Sonex also put out a letter stating that any aircraft certified over 1150 lbs. gross was not light sport compliant because of wing loading and could not be flown by a Light Sport Certificate holder:
Also on this site: Gross Weight Advisory (LSA Compliance) [Sonextalk, 1.16.13] - General / Announcements - SonexPilots.org
That is just not true and seems to be a deliberate attempt to dissuade users of optional engines (Corvair, Continental, Viking, etc.). No where can I find a limit for wing loading on a light sport plane. But even if there were, a Cleanex at 1250 lbs. is still less wing loading than an FAA & ASTM approved Dova Skylark LSA with higher numbers.
Skylark light sport aircraft- Skylark USA
Then we get a boost in gross weight to 1220 lbs. which really belies the false letter from above as Sonex found themselves losing when MOSAIC appeared. I believe that the true & safe gross weight for this airframe to be 1250 lbs. I have set, tested, and flown to this weight as have many others of which some in the Jabiru 3300 crowd is found.
I have no idea why the things listed above were done except to say that Sonex was trying to force the market to buy the Aerovee engine (they did also approve Jab 22-3300). That strategy appeared to work in the beginning as you could buy a set of plans, install VW engine and be flying for cheap. But then came concerns with the original Aerovees (six props lost IIRC) and the first edition Aerocarb with the disastrous “push open slide” that caused a friend of mine to end up in a field and gave me a fit returning from a fly-in event in another state. I try to learn from these kind of mistakes and so I determined that I would not fly behind an Aerocarb anymore.
As the inadequacy of the Aerovee for the airframe kept growing with crashes, overheating, burp issues with the Aerocarb, yada, yada, builders began to look elsewhere for engines but many were driven away by news that nothing else but a VW or Jabiru would qualify. My goodness … even the 912 Rotax was banned at the beginning as it was deemed too complicated and not simple enough.
Some became a bit infuriated at a company selling experimental aircraft trying to regulate and demand how the builders used their products in the experimental world. We were even instructed to not use the company name if we were installing the forbidden Corvair engine on their airframe.
It was humorous at times as William Wynne posted on his site:
Above, Dan and his Cleanex in front of my hangar at Corvair College #8. (2004) Until his airplane was done and flying, we kept Dan’s identity a mystery. At the time, a few people who saw this photo made jokes about the “Builder Protection Program” with a nod toward John Monnett’s allegededly sharp temper about people putting other engines in his designs. In reality, Dan is friends with the Monnetts. The Cigarette was part of the ploy, Dan has never been a smoker. Today, Sonex ltd. has a much more relaxed attitude about alternative engines.
So all of that to say this … if Sonex were to welcome other engine options it would be helpful.
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Builders having a company that says “that’s not what I would do but we’ll help all we can” would be refreshing.
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They could admit that the structure is safe for an amount up to 250 lbs. but weight/balance & C/G will need to be addressed.
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Stop telling the lie that a Sonex at 1250 lbs. isn’t LSA compliant.
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Let builders know that mounts are available for the model A and work to have mounts for other models available.
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Set up FWF parts such as cowlings, bafflings, props, nose bowls, spinners. etc. or show where to source them.
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Stop the deliberate shaming of those that want to use an alternative engine.
Corvairs work, they are available, they are reliable, parts are reasonable, and this company needs to get on board with helping builders in everyway they can.
I really want this company to survive and I believe that attracting builders is easier if you try to work with them rather than against them.
Dunno if this helps …
Dale
3.0 Corvair/Taildragger