Raptor Composite Aircraft

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TarDevil

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Jun 29, 2010
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I read with interest all your comments. I assume you all have pilots licenses but how many of you have a degree in Aeronautical Engineering? My guess, none of you. Maybe Peter doesn't either but he's having a go at building a somewhat different aircraft. At least he's not having a go at your lack of support. You all think this is a disaster waiting happen, what are you going to say if it turns out to be a complete success? Too cock sure of your presumed knowledge IMO. Time will tell.
Yep, I think this has been adequately covered.

So now a blunt perspective from a non aeronautical-engineer but a commercial pilot with instrument and multi ratings - if you can't do the math as a mere pilot, please only fly as a passenger.
 
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BoKu

Pundit
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...You all think this is a disaster waiting happen, what are you going to say if it turns out to be a complete success? Too cock sure of your presumed knowledge IMO...
I figure that there's about a 0.02% chance of that happening. So in 10,000 relatively parallel timelines, two of them get successful Raptors. This has been a pretty glitchy timeline lately, but I don't think it's glitchy enough to be one of those.
 

gtae07

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Dec 13, 2012
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Savannah, Georgia
I read with interest all your comments. I assume you all have pilots licenses but how many of you have a degree in Aeronautical Engineering? My guess, none of you. Maybe Peter doesn't either but he's having a go at building a somewhat different aircraft. At least he's not having a go at your lack of support. You all think this is a disaster waiting happen, what are you going to say if it turns out to be a complete success? Too cock sure of your presumed knowledge IMO. Time will tell.
My degree says "Aerospace Engineering", but close enough, and I've been working in engineering with real aircraft systems since I started out as an intern in 2004. I haven't followed this project too closely (too busy building my airplane and working) but from what I have seen, my comments would echo those made over and over again by the other experienced folks here so I won't bother typing them out.

As one of my professors would say, the project is "promising some pretty sporty numbers".
 

cblink.007

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Jul 7, 2014
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284
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Texas, USA
how many of you have a degree in Aeronautical Engineering? My guess, none of you
BS Aerospace Engineering
Master of Aeronautical Science
Graduate, US Naval Test Pilot School
Flight Test Engineer on two high profile military flight test programs
Certificate, Airline Transport Pilot (2 type ratings)
Certificate, Commercial Pilot (Airplane, Helicopter, Powered Lift, 2 type ratings)
4,900 hours at the wheel and counting
Certificate, Mechanic (Airframe & Powerplant)

...completely unqualified to express concern regarding this aircraft project. We would all like to see it successful; we are only calling it as we see it!
 

wsimpso1

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Oct 18, 2003
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Saline Michigan
BSME, MSME, MSIOE, 37 years as an engineer, 23 years in powertrain engineering including all manner of vibration management including solving one airplane project torsional vibration issue, lots of successful programs, Private pilot with an instrument rating and 2200 hours, about 70% complete on a fiberglass airplane of my own design and progressing.

There are lots of capable and experienced folks on here. Besides engineers and test pilots, we also have many A&P, IA, serial builders, shop experienced folks of many directions. If we are criticizing this ship, it is primarily out of concern for the safety of the aircrew and the security of the investors. We would love to see its goals met, but have strong reasons to believe that it simply can not, even if it sheds a bunch of weight.

Let's be careful about challenging the motives and capabilities of members on here, particularly when done without basis.

Billski
 

Toobuilder

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Constructive criticism takes a lot of effort and there is plenty of it on this site, but its really only worth the investment if there is some hope it will alter to course of the project under critical review. With almost 4,700 posts on this particular project, its abundantly clear that there is no hope of influencing the project manager.

Really, the value of this thread is to illustrate how NOT to do things. Its like reading a detailed accident report after the fact - but fortunately nobody has died yet. Here's hoping it stays that way.
 

cheapracer

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Sep 8, 2013
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Australian
I'd prefer constructive criticism.
All information is constructive, many here building, planning, modifying ect their own planes, and knowing the wrong way to do things is of great value, by placing the correct methods into context.

How many times have you heard someone explaining something, and adding: "Don't do it this way, because ....".
 

poormansairforce

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Mar 28, 2017
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Just an Ohioan
I will say he won the lottery as the odds of the plane being a "complete success" are about the same as winning the lottery
Hmmm....take the cost of a new Raptor and buy a truck load of lottery tickets. You may be on to something. At least you'd get a lifetime supply of toilet paper out of it!

I actually feel sorry for Peter at this point...there is nowhere to go. No money for another try and he needs to deliver a product.
 

BBerson

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I'm in complete agreement! But I think Peter believes he only needs one build and I say 'build' because he was/is convinced that He, using CAD, CNC, etc, would only need one! Based on his responses to his critics I cannot imagine what he will say to the idea of doing again or a couple more times. Now that the weight has gotten away from him he is between a rock and a hard place.
Does CAD calculate weight? I think a designer only learns how to hit a design weight after considerable experience getting stung with overweight prototypes.
 

cblink.007

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Jul 7, 2014
Messages
284
Location
Texas, USA
Does CAD calculate weight? I think a designer only learns how to hit a design weight after considerable experience getting stung with overweight prototypes.
I know with AutoCAD you can, and I can assume you can do it with Solidworks as well (we are currently transitioning to SW...).

As a rule of thumb, I use the known weight of the fabrics used (number of plies and area of each ply), and multiply the weight by 2 (for the resin), and do something similar for the core materials (ie volume). It seems to work pretty well; it is close to computer predictions, and not far from actual results with the projects we have done so far. We are very conservative in our tabulations; we like to estimate high.
 

Marc Zeitlin

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Dec 11, 2015
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Tehachapi, CA
Does CAD calculate weight?
If you assign material properties to each part, then yes - it can give you a weight roll-up for parts, sub-assemblies and overall assemblies. With composites, it's harder to be accurate, as wet layups can vary substantially in thickness and resin content, and even with prepregs, it's harder than with metals. Also, adhesive bonding is never as accurate as one assumes for bond-line thicknesses, and then you've got poorly controlled squeeze-out amounts, so there's a built-in error there, and it's never in the right direction. But you CAN get close.

But of course, at Scaled, we attempted to get estimated weights for everything and match the estimates against our actual part weights so that at least we knew what our errors were over time.

Peter as much as said that he didn't know how to get weight estimates out of Solidworks, so never tried.
 
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