Raptor Composite Aircraft

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

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  1. Sep 11, 2019 #1621

    rv6ejguy

    rv6ejguy

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    The Graflight diesel V8 will be in excess of $100K I predict since it was designed to be certified and was years in development and testing.

    30-50% better fuel economy than existing SI engines? Complete nonsense. That would be a BSFC of .266 to .19 which is better than any diesel ever made. Why do aero diesel manufacturers always BS like this? It just makes them look bad.
     
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  2. Sep 11, 2019 #1622

    pictsidhe

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    Maybe that economy relates to the $$$ per flight?
     
  3. Sep 11, 2019 #1623

    FarmBoy

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    Quite true unfortunately given the target TBO and the price of comparable (but lighter) TSIO-550s or TIO-540s. Wouldn't be surprised at $120K+ though maybe they are offering pre-certification sale pricing of only $100K :)
     
  4. Sep 11, 2019 #1624

    flyboy2160

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    The Raptor videos just continue to be an entertaining reality show. What will happen in the next episode?! Did anybody else catch him realizing that the nose leg he has already includes a built in shimmy damper - after he designed a scissor fork and external damper?
     
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  5. Sep 11, 2019 #1625

    rv6ejguy

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    I think it's slowly dawning on him that he's not as smart as he thought he was back in 2013. Learning to build a successful aircraft of this complexity by trial and error will take a very long time without some professional help. I'm waiting for the installment when Elliot gives him the thumbs up or down to fly it and what the to-do list is before he gives it a try after Reno.
     
    Last edited: Sep 11, 2019
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  6. Sep 11, 2019 #1626

    Vigilant1

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    If this were a government funded project, at this point Peter would be looking for a way to solicit some new major or minor requirements (aerobatic? submersible? STOL? added cup holders?) so he'd have a fig leaf to explain the schedule slips, cost increases, and weight gain.

    I think it is time to do what can be done to avoid drawing attention to the empty weight. For starters, maybe give all future weights as stones/pounds.
     
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  7. Sep 11, 2019 #1627

    pictsidhe

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    He found out that it already had a shimmy damper thanks to a helpful youtube commenter. It seems like he has now read the installation instructions and is following them! I had a sneaky feeling that he may have cheaped out on the retaining compound and used threadlock, but I was wrong there. It seems like the AC failed as it was installed with inadequate oil. probaly just the oil in the compressor. I wonder who did that? Now it looks like he is just going to swap the $400 compressor and not bother flushing the system or changing the dryer.

    I can't see any sane pilot touching this with a barge pole before it has survived a sustained full power test, which Peter seems rather reticent about doing. A maiden flight is not the place to verify that the engine will hold together for more than a few seconds at full power.
     
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  8. Sep 12, 2019 #1628

    FarmBoy

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    Without an EGT limit programmed in his EFI I'm not sure what sustained full power means with his current turbos other than the potential to exceed 1750F for a sustained period and melt his pistons.
     
  9. Sep 12, 2019 #1629

    TarDevil

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    Yeah, @1:50 in the last vid he bragged about how clean and new the exhaust manifold appears so he doesn't think the temps are excessive.
    How much total time has the engine logged at those temps? More than a minute?
     
  10. Sep 12, 2019 #1630

    pictsidhe

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    A diesel that doesn't have any soot in the exhaust? I've never seen that before.
     
  11. Sep 12, 2019 #1631

    Turd Ferguson

    Turd Ferguson

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    He's running DEF?
     
  12. Sep 12, 2019 #1632

    rv6ejguy

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    The temperature comment was absurd. Since the manifold didn't show any signs of distress he assumes the engine won't either. How many different people have told him 1750F EGT is way too high on a diesel in the YT comments? I guess he'll find out the hard way...

    Hasn't even run 5 minutes at TO power yet.
     
  13. Sep 12, 2019 #1633

    pictsidhe

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    Hey, look on the bright side, it will probably disassemble itself before it gets the chance to kill anyone.
     
  14. Sep 14, 2019 #1634

    FarmBoy

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    At least it will be cold in the cabin now when the pistons melt! :cool:
     
  15. Sep 14, 2019 #1635

    pictsidhe

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    No, deaf to advice.
     
  16. Sep 15, 2019 #1636

    Scheny

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    I don't know where to begin after seeing his weekend update...

    The ailerons are moving more under the influence of gravity than the sunshades. When he taxied with the cam mounted under the wings, you could see the ailerons wiggle by almost a 10°. I really like his design, no matter whether it will reach any goal, but this is a serious death trap issue.

    He thinks the integrated shimmy may be under dimensioned for his plane. One can see, that there is absolutely no guidance to the wheel once it vibrates. My guess would be that the rudder steering is as loosely connected as the ailerons. Do you also think that a "more firm" connection would solve the problem?
     
  17. Sep 15, 2019 #1637

    Venom

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    Astute and accurate observation. I agree with you. It will be very intetesting to see how the RNO showboat deals with this.
     
  18. Sep 15, 2019 #1638

    pictsidhe

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  19. Sep 15, 2019 #1639

    pictsidhe

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    The nose wheel is free castoring. There is no connection to the rudder, hopefully that's worse than the ailerons? Low speed steering is by differential braking. There is some built in self centreing in the strut. Having seen the close up video, I'm wondering if the gear just isn't attached rigidly enough to the bulk of the beast. That could well be a fuselage issue. After seeing the first aileron debacle with horns attached to skins, we know that he is lacking in structural sense. I've suggested that he balances the gear around the shaft axis, which might help, but that may just increase the speed for the onset of shimmy. It's a simple band-aid... Otherwise, he is going to need to do some structural reinforcement. Which I have doubts he will manage to do by glueing a few stiffeners on. Reducing the rake will probably increase shimmy onset speed. With a Vr of perhaps 100kts, he needs to make some major improvements.

    Somebody needs to test the stiffness and strength of the aileron and elevator linkages. I can't see Peter doing it. If anyone knows the test pilot, there are some videos that he must watch and some check that he must do before getting inside... The first shimmy video had the elevators travelling stop to stop. These are just issues we can spot from videos. You can bet that there's a whole load more that aren't so obvious.

    300hp at 25k with properly matched turbos and 70% intercooler effectiveness is going to put ~35kW of heat into the fuel. Those wing tanks have foam cored sandwich skins... I wonder if he is bright enough to be monitoring fuel temp?

    It does indeed look cool, but I'd not want it to fly over my house...
     
  20. Sep 15, 2019 #1640

    flyboy2160

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    Let's make a gentlemanly, friendly wager. I'll take the opposite view: I don't think he will realize anything about his competence slowly. He will continue blithely along his know-it-all-don't-bother-with-engineering-I'll-just-try-it until there is a major catastrophe that is inescapable and that he can't Youtube away.
     

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