Raptor Composite Aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Dexacare, Mar 28, 2016.

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  1. Jun 17, 2019 #781

    pictsidhe

    pictsidhe

    pictsidhe

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    A girlfriend's 12 year old son once asked me:
    "How do you know so much?"
    "I've never stopped learning" was my reply.

    Nobody knows everything. Everyone can teach you something.

    That kid was 1/3 my age and not the sharpest knife in the drawer, but I picked up a few nuggets from him, too.

    Thinking that you know everything is the mark of a fool.

    Whenever I come up with something that is a quantum leap ahead of currently technology, I'm pretty sure that it is time to find the mistake(s) that I've made.

    Designing an aircraft needs thousands of small pieces that are simple to design on their own. Getting them to all work harmoniously is where the real difficulty lies.

    I am working on an IT project right now. I had absolutely no problem throwing out 1/3 of it a few days ago because I found a better way to do that chunk. That is a lot harder to do with an aircraft as the major pieces are so interdependant.
     
  2. Jun 17, 2019 #782

    BBerson

    BBerson

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    It is a hard choice to throw out an overweight aircraft. But not much other choice.
    I built an an overweight prototype... so I have some insight.
    The design tends to gain weight because of lack of strict weight control.
    What I do now is assign a weight goal for each major component. Then I design to that weight goal and start building the major part. If it looks like it can't meet weight, I look for a different method. Finishing overweight parts is illogical.
    It isn't "quitting" to abandon an overweight part. It is "education" for the next part.
     
    Last edited: Jun 17, 2019
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  3. Jun 17, 2019 #783

    TMann

    TMann

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    I'm just glad I'm not working on this project. It sounds as though Peter (right or wrong) doesn't really have a team behind him.
    I think everyone involved knew what the project definition was even before the purchase of the gantry CNC. Right?

    I'm not familiar with how (for the lack of a better example) ICON did their prototype. Was it a true prototype or a display model? I've never walked into their display at Oshkosh. The odor of Kool-aid was too strong for my taste. I do believe that Peter's intent was to build a floor model that actually flew.

    Dissent here at the Forum is pretty much a given. Dissent within the ranks is another thing entirely, especially as a public display.

    I wonder who will make the next attempt at a new design?
    No wonder Kelly Johnson worked out of a tent. :)
     
  4. Jun 17, 2019 #784

    Marc Zeitlin

    Marc Zeitlin

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    The prototype ICON A5 was a flying testbed for zillions of ideas, and it flew hundreds of hours and was modified countless times It started flying in 2008, IIRC, and was still being used when I left in 2012. The display models in the showrooms and at OSH USED to be non-flying mockups, used to show cockpit design, overall architecture, paint schemes, and wing-fold capability. I believe that now, the showroom planes are production models off the assembly line - certainly the unit at OSH last year was.
     
  5. Jun 17, 2019 #785

    pictsidhe

    pictsidhe

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    While I haven't started construction, I have been testing out ideas and construction methods. My round file is getting plenty of use. I've been using the city provided 'deep storage' for many of my better round file ideas ;)

    I am also setting target weights for parts. For want of a better guide, I am using part weights form other ultralights; the legal eagle and Minimax. since my construction is very different, I am using assembly weights. Some of my individual parts are half the weight yet double the strength of the minimax/eagle parts. Others are heavier. Large assemblies, mostly similar. Not meeting a target weight does not mean I will abort a part, especially if I have already redesigned it 6 times. But it will make me very displeased and get filed in the 'needs improvement' file. I will have to make something else lighter to compensate. That is no mean feat on a 103. Beating my target weight makes me very happy, as I can compensate for the fat parts or even add bling when the design is nearing completion. I have a long list of bling I'd like, but am not sure is possible. AC is not one of them...

    "One who makes no mistakes makes nothing." Giacomo Casanova
     
  6. Jun 17, 2019 #786

    BBerson

    BBerson

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    Making " something else" lighter assumes you didn't already get it as light as possible. I am starting all the major parts at the same time to see if all my target weights are still in process. No sense in detailing any one major part if the whole is in major jeopardy of not meeting target weight.
     
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  7. Jun 17, 2019 #787

    pictsidhe

    pictsidhe

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    I have been doing much the same thing. Rough designing everything to see what should work and what needs to be round-filed. Each significant part redesign often require several other parts to be redesigned, sometimes completely changed, which then triggers other redesigns. It's tedious.
    But, it seems to be converging now.
     
  8. Jun 17, 2019 #788

    Jay Kempf

    Jay Kempf

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    Hadn't been to this thread for a while. Wow! Fast approaching cliff at least reached, maybe passed it by, and now in a downward trajectory in all aspects of business and engineering. Sad. There were some things I really liked about how this was going. There were some real worries but in terms of how to prototype something complex a lot of fun stuff was going on. If this lives on only to show individual efforts and what to do and not to do it still has worth. Everyone was rooting for this team. Nobody likes to see anything go to waste. I personally spent a year of my life on one experimental program that never happened. It's never fun. Cheapie: calm down and step away from the internet ;)
     
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  9. Jun 17, 2019 #789

    BoKu

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    Sanity check for the win!
     
  10. Jun 18, 2019 #790

    Scheny

    Scheny

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    I was hoping to see it fly, until I saw the ailerons wiggle on the taxiway. Note I'm also convinced it is a death trap. In my opinion you can learn every time and if it only has been for the video coverage. So even Peter being Peter has had some benefit, as no other PM would have done such disclosure.

    Thanks Jeff for your enormous efforts! Don't consider it waste of lifetime, consider yourself being actor in a reality show. Without you, there would be nothing at all and your work speaks for itself.

    As for the SR71: hypersonic planes are only bound by temperature, both by engine and hull. They would accelerate until the engines melt :cool:
     
    Last edited: Jun 18, 2019
  11. Jun 18, 2019 #791

    Marc Zeitlin

    Marc Zeitlin

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    This certainly has almost nothing to do with the Raptor, but let's assume materials capable of dealing with arbitrarily large temperatures - say up to 100,000 K. So heat's not an issue. Please explain how, with drag being approximately proportional to velocity squared, but thrust from a ramjet being proportional to velocity, hypersonic aircraft could accelerate to arbitrarily large speeds without the drag ever being equal to the thrust (thereby stopping any further acceleration)?
     
  12. Jun 18, 2019 #792

    Scheny

    Scheny

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    I replied to #777 for the SR comment. The Ramjet has almost no moving parts, so you can inject more fuel and accelerate until you reach melting temperatures. I have a picture showing the operating temperatures somewhere if you want.

    Of course one of the few problems the Raptor doesn't have
     
  13. Jun 18, 2019 #793

    Topaz

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    DreamWings. The poster-child for, "We are going to revolutionize sport aviation, and we have our undergraduate aero engineering students working on how we'll prove it!"
     
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  14. Jun 18, 2019 #794

    mm4440

    mm4440

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    The SR reference was an interesting aside. The point of the post was a GA aircraft cruising efficiently at 25k feet would need to look like a U-2 or if you insist on a canard, like a Voyager; long straight wings, motorglider like.
     
  15. Jun 18, 2019 #795

    Marc Zeitlin

    Marc Zeitlin

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    Ramjets are most efficient around Mach 3 and run out of steam due to heating of the intake air from compression around Mach 6.4. In order to go faster than that, you need a Scramjet, which no-one's been able to actually get to work consistently. Maybe you were thinking of Scramjets.

    Agreed.
     
  16. Jun 18, 2019 #796

    pictsidhe

    pictsidhe

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    Well, it's taken 40 pages, but now we are stuck at mach 6.4. I didn't see that coming ;)
     
  17. Jun 19, 2019 #797

    pictsidhe

    pictsidhe

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    I said a week or two back that I hadn't done performance calculations for my own project. I was confident it would fly nicely whatever the numbers, that I'd be Skeptical of, were.

    Well, I just fixed that.

    Using the Cd0 from tests of the full size Mk1 of 0.026 and e of 0.9, I get a sea level top speed on a FAR103 legal 15hp of 79mph.
    Initial rate of climb, 1500fpm
    It will top out at 40,000' and a TAS of 75mph.
    Range of 469 miles, almost as good as the full size one.
    Pretty decent huh? In fact, it's a quantum leap ahead of any other 103!

    So, if 500 people want to plunk down $5k each, I should have your aircraft ready for OshKosh 2020!

    Gotta take my drugs now then look for bling to blow your, errr the project, money on.
     
    Last edited: Jun 19, 2019
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  18. Jun 19, 2019 #798

    rv6ejguy

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    Hey guys, why don't we try to keep this thread on topic...
     
  19. Jun 19, 2019 #799

    Scheny

    Scheny

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    I just checked all automotive conversions I am aware of and there is only one commonality. The gearbox if you would call it that is ALWAYS mounted to the connection points on the motor block where the clutch would be in a car.

    @canardlover is there any reason Peter didn't take this into consideration? It would be way less effort to get rid of the oil and construct an electric pitch actuator instead. It would even be the classic IT solution to fix it in SW if you experience a HW problem :D
     
  20. Jun 19, 2019 #800

    pictsidhe

    pictsidhe

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    Maybe it's electrically controlled hydraulics? I wonder if his control theory is up to scratch.

    Elliot Seguin and someone else are going to take a look at it. He will be unhappy if a second test pilot says no thanks.
     

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