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Raptor Composite Aircraft

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wsimpso1

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Martin Hollmann wrote some books that are very good at explaining how to design composite aircraft structures, listing material properties, how to perform structural and FEA on them, and even aerodynamic flutter analysis. His widow is still selling them through his AircraftDesigns.com website. There are other good books out there on this subject, too, so other than illiteracy, there is no good excuse for not crunching the numbers and verifying the design is sound before ordering materials. If you’re building a tube & fabric airplane with <100hp, then go ahead and draw those chalk lines on the hangar floor, but for a high performance aircraft, to eschew the now ubiquitous design resources is negligent at best, stupid at worst...so why would someone want to help fund this?
We really should not go telling a new batch of folks Hollman's stuff was good guidance on anything.

Hollmann's approximations on composites are unreliable for design and downright scary to this engineer. His shortcuts have resulted in major misses on composite structural designs when tested. Lancair two seaters built to his designs proved much weaker than he anticipated, requiring iterations of test and beefup because he did not understand structures and materials. He never even acknowledged that he screwed the pooch, and I believe it was a case of he had no idea what he did not know.

In his FEA work, the codes he demonstrated do not handle directional materials/composites well, so the methods are then unreliable for composites. All of his modeling was based upon his erroneous approximations of lamina load/strain relationships - very much GIGO.

Then the entire topic of FEA is one that requires both significant training and experience before reliable results can be expected. GIGO applies again, and I am reluctant recommend it to folks. The first step is to do the more conventional closed form calcs and much of what we do in airplanes can indeed analyzed and designs settled with those calcs - no FEA needed for much of it.

Billski
 

bmcj

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We really should not go telling a new batch of folks Hollman's stuff was good guidance on anything.

Hollmann's approximations on composites are unreliable for design and downright scary to this engineer. His shortcuts have resulted in major misses on composite structural designs when tested. Lancair two seaters built to his designs proved much weaker than he anticipated, requiring iterations of test and beefup because he did not understand structures and materials. He never even acknowledged that he screwed the pooch, and I believe it was a case of he had no idea what he did not know.

In his FEA work, the codes he demonstrated do not handle directional materials/composites well, so the methods are then unreliable for composites. All of his modeling was based upon his erroneous approximations of lamina load/strain relationships - very much GIGO.

Then the entire topic of FEA is one that requires both significant training and experience before reliable results can be expected. GIGO applies again, and I am reluctant recommend it to folks. The first step is to do the more conventional closed form calcs and much of what we do in airplanes can indeed analyzed and designs settled with those calcs - no FEA needed for much of it.

Billski
I agree. I got some of his books (directly from him) and I was not at all impressed with his methods.
 

cheapracer

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When investor money is greater than the principal's contribution the risk of fraud grows exponentially.
"the principal's contribution" of course isn't just money, it's assets, IPRs, education level, management history and knowledge/capability, i.e. everything the Principle brings to the plate. In law in China, this is actually valued as a monetary figure in the contract.
 

Venom

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....... began taking deposits before he had a deliverable product.......
BJC
He still has 5000 of my dollars....but it wasn't a deposit.....it was the purchase in full of a kit.
And I too met him many many years later, but I didn't get the same impression that you did.
I walked away thinking "Jesus this guy is nothin' but a saleman"
 

cheapracer

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What do they say about a fool and his money?
Donate to the Raptor project?

I just watched both the latest videos, he whines about the pulley safety guards not being noted, but Wasabi rejected the entire system, they weren't to know he would keep and modify it. I presumed the guards were locked with with the axle bolts, apparently not, what a stupid idea that they rotate, and only himself to blame.


As for his new sidestick control, I can think of 2 easy solutions off the top of my head, but he has it in mind that the SR22 system is best, but I believe the way he has designed it is poorly engineered. The guy just has no practical hands on experience in his background to sort these problems out.

joke.jpg


This all comes back to "fly it first". Now he finds the air-con is in the way, well, if the priority had been to fly it first as a bare, minimal craft, these modifications that were always on the cards, would have been far easier to conduct.
 

berridos

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madrid
This thread looks like a daytrader forum. Building planes is so much more interesting than judging investments and discussing what people do with their own money. Peter is a bit incompetent, but for sure he hasnt set up a fraud scheme. In the stockmarket there are every second people investing in loosers and we dont write 4400 posts about it. There is a pretty perfect consensus in this forum that the project wont succeed. Even a perfectly managed GA business is a poor investment thats why this forum exist and we keep things in the garage.
 

davidjgall

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Oct 7, 2010
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Northern California, USA
I just moved all of the posts concerning Canardlover's projects to the Design area under an existing thread called Cool New Canard Designs.

This thread is huge, let's not dilute it with other airplanes.
Billski,

Unfortunately, you've also moved posts from canardlover and others (TFF) that were directly germane to the Raptor thread including canardlover's explanation of the Raptor primary structure, and you seem to have lost my post entirely. I appreciate trying to control thread drift, but loss of continuity makes following a thread difficult and without at least creating links from the questions to the answers (or even a link to the thread) you've broken up the conversation and nulled my retort to Venom's broadside against canardlover.

Perhaps a do-over is in order....
 

TarDevil

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Jun 29, 2010
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Coastal North Carolina/USA
New video out, he's managed to design the control stick to be 3 times as a heavy, and 5 times more complicated, the 'Raptor Ethos' is being upheld ...

View attachment 97679
I saw that mass of metal, thinking "Does Peter think there's any limit to what Raptor can carry... in the air.... on it's own power?
 
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