Aeronca 11AC Chief Project FS

On Jul 7, 2:00 am, cavelamb himself wrote:


You are coming off pretty snotty, VB.

Show and tell time.

Let's see the airplanes you have designed and built...

I'm holding up my end of an argument, against three or four people who
are being equally snotty. I would be delighted to raise the level of
this "discussion" up to a more genteel level, but it would require the
same commitment from others... who immediately came after me with both
barrels right out of the gate.

As for show and tell, I did not and do not claim to be an aircraft
designer. I've sketched on paper, and head-scratched, and dreamed just
like everyone else on the homebuilt newsgroup. However if you read the
thread from the start I went out of my way to not masquerade as a
structural engineer, and to compliment Chris Heintz on actually being
one.

I will claim only this:

1. After having built and tested and crashed and succeeded and failed
with hundreds of balsa model airplanes, and after having owned 15 or
16 full size aircraft, and after having gone through A&P mechanic
school, and after having listened and learned from several people with
engineering knowledge far greater than my own, and after having
tinkered good and bad with small sheet metal projects on several
airplanes... I have a little better understanding of what I am talking
about on this thread than (let's say) half of the people here.

2. There are some people who probably have a lot more engineering
knowledge than I, there are some with a lot less, and there are a few
with engineering degrees that I definitely do not have.

3. I looked at a CH-601XL and found a fairly obvious problem. I
pointed it out to an Aerospace engineer / A&P in our EAA chapter and
he said there was too much movement there but there might not be any
assymetrical loads on it.

4. There have been now SEVERAL 601XL in-flight wing failures, one or
two new ones since I made the comment that started this flame-fest. If
my big mouth keeps a couple of people from burying their heads in the
sand on this issue, then perhaps there is some good being done.

5. Although I know damned well there are people on this newsgroup with
engineering degrees and greater sheet metal knowledge than mine by
far, for some reason they have NOT participated and NOT explained if
I'm wrong and NOT explained if anyone else is right.

6. I own a CH-701 mini-project (plans and a few tail parts built), and
I would love to build it and fly it. I am a very strong supporter of
Chris Heintz' designs for the most part. He has done something
brilliant, made the airplanes easy to build, and extremely simple.

7. But if Kelly Johnson can make a mistake, and Ed Heinemann, and Kurt
Tank, and Willy Messerschmitt, and Andrei Tupolev, and Matty Laird,
and Igor Sikorsky, and Bill Stout, and even CG Taylor can make a
mistake, then so the hell can Chris Heintz make a mistake. It is my
GUESS that he took the original 601 Zodiac and tried to make a sexy
low drag wing for it, at the same time as he was fighting like hell to
get it light enough for the new LSA category. He had to push too hard
on some engineering issue (or more likely several small ones), he had
to go to a lighter skin gauge or thinner shear webs or spread a load
across too few bolts or something I do not have the college degree to
understand ... and the strength of the airplane fell between what was
good enough on paper and what the real world of ASSYMETRICAL flight
loads or gusts or sub-par workmanship requires.

8. If I'm being snotty I apologize, but I will return fire when fired
upon. And as you can see I will fully substantiate my arguments,
unlike some others here !

From a highly experienced airport bum and highly NON-engineering-
degreed mechanic, I am telling you all that there is an issue on the
tail mounting of the Zenair design. I don't know if it is a big
problem, a fatal accident waiting to happen, hugely overbuilt, or
something that will wiggle but never break. That is a question for the
engineers to clarify but someone needs to look at it.

I'm saying that there is a tragic problem with the CH601XL airplane
design. There are too many catastrophic structural failures that
cannot be swept under the rug of builder error or amateur aerobatics.
If it is a design flaw by Heintz, then he is still a great designer
and deserves the same respect, but he will have to find the problem
and issue a repair or upgrade.

Bill Berle