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Raptor Composite Aircraft

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wrmiles

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Oct 13, 2019
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18
Just when we all think things can't get any worse, this is a reply from PM to one of his disciples from the latest YT Video.
Please get the white coats on standby
" Wonder what 'Pixie Dust' drugs he uses ( & where can I get some )
Alfred Gabelli2 days ago
Peter, add flaps to get the landing speed down. Congrats.

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Raptor Aircraft
Raptor Aircraft

2 days ago
That's a future plan.
Didn't flaps on a canard work great for Beech?
 

flyboy2160

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May 25, 2014
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california, USA
...And, even more important than the amount of deflection is the damping. Notice how long it takes for the oscillations to damp out and stop. It seems to keep vibrating at its natural frequency after he lets go, like a diving board will resonate at its natural frequency long after the diver has jumped off.

It's this lack of damping, combined with possible excitation from the tip sails that is exacerbating the situation. Even if the amount of deflection is acceptable [which, in my opinion, is not the case], the damping is not.
....
Jet, I've been with you all the way until this damping deal. (LOLOLOLOL like the scene in Top Gun in which Jester says ~ 'That's some of the best flying so far, right up to the point where you got killed.')

Uh, uh, my school daze recollection is that you're not going to get much damping in a stiff composite structure. I have little sections of missile wings skins that don't appear to damp out 'better' than his wing.
 

WonderousMountain

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Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Theoretically Supersonic area drag is valid to zero.

Formula has it falling off by a square root. So take
Full Mach 1 section interference drag, at half mach
squared, you are at A quarter. If it were 100, it will
be 25. Now Raptor guy porpoised near mach 1/5,
the square of which now makes 4 pounds, around
1-2 HP worth.

So you could potentially see a 12 knot benefit should
Raptor find several hundred horses. (Add some stability)
 

slociviccoupe

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Joined
Apr 1, 2011
Messages
306
Location
Palm Bay Fl.
Getting into this discussion very late. But are you kidding me using water to air intercoolers. Ive used them on cars with sucess but generally have very large heat exchangers. Fans and lots of water. Even dry ice in a cooler with coiled aluminum tubing. No way any of that would ever work. Even worse did i inderstand running fuel through them instead of water? Not to mention his static testing with a 55 gallon drum and a plate type heat exchanger?
Next thing why an engine no one knows anything about? He could have a running proven engine package with an ls based engine.
And lastly aside from making fuselage more rounded why not follow the velocity, the cozy and other flying proven airframes.
There is something seriously wrong with this guys ego. Im a nobody but even if doing different construction techniques id still follow closely proven designs.
 

pictsidhe

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Jul 15, 2014
Messages
8,801
Location
North Carolina
Jet, I've been with you all the way until this damping deal. (LOLOLOLOL like the scene in Top Gun in which Jester says ~ 'That's some of the best flying so far, right up to the point where you got killed.')

Uh, uh, my school daze recollection is that you're not going to get much damping in a stiff composite structure. I have little sections of missile wings skins that don't appear to damp out 'better' than his wing.
Damping is generally mostly aerodynamic. Static tests need mathematical mangling.
 

Marc Zeitlin

Exalted Grand Poobah
Joined
Dec 11, 2015
Messages
754
Location
Tehachapi, CA
... My advice that he call up Marc Z and ask for help to fix his aeroplane has, of course, disappeared.
While I appreciate the vote of confidence, Marc Z. (assuming you're talking about me) has long since stopped remembering enough about aircraft design and analysis to actually design or analyze an aircraft, and I don't allow people to hire me to do so, although I'm still capable of evaluating OTHER people's designs and analyses and giving useful feedback, so I allow folks to hire me to do that stuff :) .

Now, I do know a crap-ton of folks who DO still know how to do those things, and could recommend folks to PM, but he already KNOWS people that do those things (Mark B., his structures guy, and the guy who did his aero analysis for him and told him that the plane would not have close to the performance that he was advertising).

So, as I've said many times before, to folks who've posted the "what can PM do to fix this plane" questions, the answer is "nothing". It's a lost cause, with too many issues, and it needs to be scrapped. No one ever like to hear that, but it would be less work to start over than to fix. Even if I WAS competent to "fix" his plane, I'd tell him it made no economic or technical sense to do so.
 

Jet787

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Messages
41
Location
Northern Va
Just when we all think things can't get any worse, this is a reply from PM to one of his disciples from the latest YT Video.
Please get the white coats on standby
" Wonder what 'Pixie Dust' drugs he uses ( & where can I get some )
Alfred Gabelli2 days ago
Peter, add flaps to get the landing speed down. Congrats.

1

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Raptor Aircraft
Raptor Aircraft

2 days ago
That's a future plan.
Why is that shocking?

Funny, the Starship did that and it was also overweight. And Beech ended up buying most of them back and cutting them up. Foretelling I think. I don’t think it was Rutan’s fault, Beech and the FAA didn’t trust composites and required Beech to overbuild the AC.
 

rv6ejguy

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Calgary, Alberta, Canada
When Peter is shaking the wing, realize that he says it's up on blocks. The tires are merely touching the ground with almost no weight on them. He typically had foam blocks on top of the drums to support the aircraft and a block under the belly at the front while working on it in the videos.

The flex at the wing root is astounding there and it takes maybe 10 cycles to stop flexing after he releases it. Go and try that on whatever plane you are flying now and tell me if it acts like this?
 

BBerson

Light Plane Philosopher
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I think it could be dismantled and each part weighed to see what can be done before starting over, if that is the goal.
But a marketable product may not be the goal of a dreamer.
 

Volzalum

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Nov 22, 2019
Messages
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When Peter is shaking the wing, realize that he says it's up on blocks. The tires are merely touching the ground with almost no weight on them. He typically had foam blocks on top of the drums to support the aircraft and a block under the belly at the front while working on it in the videos.

The flex at the wing root is astounding there and it takes maybe 10 cycles to stop flexing after he releases it. Go and try that on whatever plane you are flying now and tell me if it acts like this?
Again, I do not see one side flexing. I see both sides moving equal and opposite. To me it looks like the spar that joins the wings (to make them 1 element) and the fuselage bottom are doing the flexing (i.e., changing the shape of the bottom of the fuselage), but the wings appear to be moving as a single element. It looks to me like the fuselage bottom where the spar mounts has similar issues to where he put a steel plate for his pulleys to mount to. Even in slow motion, the wings appear to be moving together and opposite.
 

Jet787

Active Member
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Messages
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Location
Northern Va
Are the NTSB going to be able to view blocked messages on his videos? They'd probably be more informative than the visible ones.
Yes and here also. The NTSB report should make interesting reading. In short it will simple state “pilot error”.
 

jet guy

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Aug 15, 2020
Messages
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...LOLOLOLOL...
Yeah, I would be interested in hearing what, if anything, you actually know about vibration and damping [besides your 'observation' about 'little missile wings'].

The simple fact is that damping characteristics are EXTREMELY important in aircraft structures and much effort is expended to find things like damping ratio and damping coefficient. Quite elaborate analysis techniques and sophisticated equipment are employed, both in ground testing and flight testing. And this is still an evolving science: modern methodologies evolved only in the 1960s.

That small amount of force Peter manually applied to the wing tip is causing way more deflection than it should...that's only a few pounds force. The flight loads, gust loads, and loads from those big tip sails is going to be substantial at any significant dynamic pressure.

Again, we see from the unexplained short mode oscillations [not caused by pilot input or gusts] that there appears to be a serious aeroelasticity problem. The apparent aileron reversal buttresses that conclusion.

Here's an interesting master's thesis that may be of interest to some here. It's a project to design, built and test a small sailplane in the ultralight category, but designed to meet FAR 23 standards. It describes the layup schedule for wing structure and load testing for bending strength, as well as vibration testing to find modal and damping characteristics.

Structural Testing of an Ultralight UAV Composite Wing and Fuselage [PDF]

They used something like 80 strain sensors in the wing load test and also made a nice little 'wiffle tree' apparatus for spreading the load on the wing. Nineteen accelerometers were used in each wing in the vibration testing.

 
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Venom

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81
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Pacific NW
So where is PM going with this? It is VERY clear, and has been for quite some time, that this airplane will never become a kit or any other form of final product. PM will not find major investors who will pony up for the huge costs of taking this project forward. So I ask again, where is PM going with this and what will his exit strategy be? Anyone have a guess?
 

Jet787

Active Member
Joined
Sep 3, 2020
Messages
41
Location
Northern Va
Getting into this discussion very late. But are you kidding me using water to air intercoolers. Ive used them on cars with sucess but generally have very large heat exchangers. Fans and lots of water. Even dry ice in a cooler with coiled aluminum tubing. No way any of that would ever work. Even worse did i inderstand running fuel through them instead of water? Not to mention his static testing with a 55 gallon drum and a plate type heat exchanger?
Next thing why an engine no one knows anything about? He could have a running proven engine package with an ls based engine.
And lastly aside from making fuselage more rounded why not follow the velocity, the cozy and other flying proven airframes.
There is something seriously wrong with this guys ego. Im a nobody but even if doing different construction techniques id still follow closely proven designs.
Yep, your late to the party, welcome.
Just go back 10 or 20 pages and that might get you partially caught up. Enjoy the reading.
 

BBerson

Light Plane Philosopher
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Joined
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Messages
13,964
Location
Port Townsend WA
Well, I think he might keep pushing forward with the Raptor just to get it to Oshkosh. He started with a tent behind Icon and a dream. His videos made him a virtual aviation rock star. Why would he end that and start a mundane factory?
 

jet guy

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Joined
Aug 15, 2020
Messages
73
The flex at the wing root is astounding there and it takes maybe 10 cycles to stop flexing after he releases it. Go and try that on whatever plane you are flying now and tell me if it acts like this?
Yeah, I agree completely. That's just an absolute gobsmacker. Maybe not for the lay person, but for anyone even mildly acquainted with aircraft structures those few seconds of video hit like a ton of bricks.

When Peter is shaking the wing, realize that he says it's up on blocks. The tires are merely touching the ground with almost no weight on them.
Yup. You can see also he has a guy holding the far end wingtip, and it still shakes. You can even see that far aileron flapping [here]. The fuselage is clearly not even rocking, due to the wings being supported on those drums.

As mentioned already, Peter's hand input is a TINY amount of force compared to what will be generated in flight. In that composite sailplane paper I linked to they measured only 3 inches of deflection at the tip of that very long and slender wing with 60 lb force.
 
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rbarnes

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Aug 28, 2015
Messages
313
Location
Texas
So where is PM going with this? It is VERY clear, and has been for quite some time, that this airplane will never become a kit or any other form of final product. PM will not find major investors who will pony up for the huge costs of taking this project forward. So I ask again, where is PM going with this and what will his exit strategy be? Anyone have a guess?
There will be a "temporary suspension of development" while he secures new investment... and then it will quietly disappear and collect dust in some hanger with the wings off to save space.
 
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