If you were in charge of Raptor...

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by dcarr, Mar 19, 2019.

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  1. Mar 19, 2019 #1

    dcarr

    dcarr

    dcarr

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    If you were in charge of Raptor and had to fly it 6 months from now, what would you change/test/do?

    Starter ideas:
    - Install 300hp IO-540 and new cowl
    - Flip aircraft and do sandbag load tests
    - Carefully review pushrods, bellcranks, and control system attach points
    - Remove any non-critical equipment (AC, pressurization, etc.)

    What say you?
     
  2. Mar 19, 2019 #2

    rv6ejguy

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    Yes, this is a good short list. Forego the paint and interior too. After testing and evaluation of the structure and control system, if it proves safe, get the thing in the air to validate performance, stability and handling and see what changes are required for a second prototype.

    The fancy stuff can be added later after a structural, weight schedule and cost review however I suspect the design will fall far short of the original performance estimates anyway. See how many people want to buy it after the real performance numbers and cost are demonstrated.
     
  3. Mar 19, 2019 #3

    TFF

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    1 Yes, 2 Yes, 3 Duh, 4 Yes. A mock-up fuselage can be made to test interiors and stuff like AC. Actually getting a prototype airplane flying should be all the program is about. Frilly stuff for down the road. If production is in the works, a second crew should be making production molds and processes that match that part. I doubt prototype stuff is up to the task. So really three crews. One building an airplane, one doing fry fru stuff, one for manufacturing. Scrap two of them if you want to fly.
     
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  4. Mar 19, 2019 #4

    jedi

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    This is not my cup of tea so I have not followed the blog closely. My answer may be tainted but my opinion is very real.

    I would look for a new job. Any aircraft program whose top priority is schedule is going to have serious problems. Many large and numerous examples.

    Make a list of what is needed, then determine a reasonable schedule. First big mistake is to make a schedule then ask what can be done. Dam! Thinking about it gives me the chills. I would quit on the spot and have no regrets.

    If the request is driven by investor demands, I would be even more firm in my decision.

    Ya got to know when to hold em and know when to fold em! This is high stakes poker and I don't want to lose.

    If I were in charge of the Raptor program and saving the company then I would like to have a serious discussion.
     
    Last edited: Mar 19, 2019
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  5. Mar 19, 2019 #5

    blane.c

    blane.c

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    I agree six months ain't happening without divine intervention. If that is a criteria begin praying now.
     
  6. Mar 19, 2019 #6

    spaschke

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    I wouldn't have developed the motor to start with. I would have gotten it flying with a plain old io-540, then developed the diesel engine. That would give builders choices. I also agree about A/C and pressurization. Get it flying first. The upholstry should be done now because it adds weight and doesn't take long to install.
    HOWEVER, given that this design is not really new and just a modified cozy/velocity/... ok, not 'just' a modified cozy. But you know what I mean. If he has the money to throw at the engine, A/C, and pressurization then more power to him.
     
  7. Mar 19, 2019 #7

    ScaleBirdsScott

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    There's definitely something to be said for trying to incorporate various systems like modern powerplants, AC, pressurization, etc if those are core features of the design; with the presumed assumption that anything can eventually fly if you feed it enough money.

    But I do think all of that can be worked in tandem with a stripped-back flight test model. I'm gonna say if it was me, the new engine is the least crucial part of the design success and the most interchangeable feature. Inevitably someone's just going to do an LS-swap or throw in a turboprop anyway. But if I was selling that engine package and needed to develop it, then it needs to be run on the ground a lot, and then an existing flying airframe for sure. I wouldn't cross streams with the new airframe until the engine has shown it can run as expected.

    As long as the flying prototype has the 'hooks' to patch in the major bells+whistles down the road then no biggie. And if those features aren't fully designed then the prototype can inform that design for the next go-around. But ultimately subsystems can be tested on a bench without slowing down the main aircraft development. The plane I'm designing is intended, and has mounting points for, retractable landing gear; but we're starting out with a simplified fixed gear setup that mounts to the same points just to avoid all the extra headache with proving out a retractable gear setup. Once we work out how it flies, and if it's worth keeping it flying, we'll go on to build a mockup of that and then transfer that to the plane down the road.
     
  8. Mar 19, 2019 #8

    Toobuilder

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    Before I'd spend another penny of engineering money, I'd bring in an INAR (independent non advocate review) team and shred the project down to it's bones. If there was any hope of an economical engineering fix the INAR would find it.

    I suspect in reality, the "next PM" is going to spend most of his time boxing and inventorying company assets for disposition.
     
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  9. Mar 19, 2019 #9

    TFF

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    Pressurized is wonderful, 99.9999% can’t pull it off. Getting that right is a major major major deal. You pretty much have to try and pop a fuselage while shaking it to see if it will break apart. Lancair pulled it off and one or two others in the million dollar club. Piston engine pressurization is a sad mess to do. Maybe if you are piper or beech. Pressure and turbine are much happier.
     
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  10. Mar 19, 2019 #10

    Victor Bravo

    Victor Bravo

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    Very first thing is I would get rid of that ridiculous windshield/window shape on the sides of the cabin and make it look more like a legitimate aircraft and less like something that was designed by Hanna-Barbera for the Jetsons. The way it looks now might appeal to uneducated people with no knowledge and experience in aviation. Immediate credibility-killer for anyone who has actually flown. Childish is the way it looks to me, like a Chinese toymaker's ARF plastic R/C model window shape.

    I would tell the designers to do the research and read about the cooling problems that Velocity had with top-mounted air intakes. I don't care what anyone says, there has got to be badly separated and dis-combobulated air flow on the top of that fuselage at high alpha. That's where you need the cooling to be at its best. Put the air intake on the bottom, where it can be smaller and more effective. Looking at the side view of the aircraft in their website's "clown puke" airflow renderings, you can see that precisely zero attention has been paid to getting air into the engine. There is just enough of an air intake stuck on it to prevent someone from asking why there's no air intake. Nothing more than that. That tells me they are designing an aircraft to attract investors, not to fly well.

    (sound of hyper-smarmy game show host with a huge fake smile saying "Oh, I'm sorry... but thanks for playing Aero-Scam!")

    I agree with the other comments about getting the first article in the air safely using standard aircraft engine, then developing the warp drive or V8 or nuke power or whatever.

    No investor or partner is ever going to be upset if the first prototype flies sooner insteadof later with a normal engine. Seeing an actual flightworthy and oeprable prototype, instead of digital renderings or ground display models, is three orders of magnitude more credible than being "in development" with a bunch of renderings and artist conceptions. Of even than a half-built hulk of a "prototype" that clearly does not fly.
     
  11. Mar 19, 2019 #11

    Topaz

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    Sadly, this project is in a really tough position. The two key elements are both in trouble.

    "If" I were in charge of the Raptor project, I'd separate the two elements: Engine and Airframe. Then I'd have a long talk with my key investors. Whichever was the "big draw" for them, the reason they plopped down funding, gets a thorough independent engineering review and/or redesign such as Toobuilder is talking about, and all the attention moving forward until it's proven. The other goes on the back burner for now. The engine seems like the longer shot for me, from the sound of things, but also the element more-likely to have been the draw for the VC guys. As has been mentioned, the airframe is, at the very simplest concept, a pressurized Cozy with retractable gear and pretensions. But that's my opinion. Only the VC people know where they saw value in this project.

    The key, IMHO, is to scale back the project, or at the very least do the two big elements sequentially so that the moment-to-moment effort is scaled back. I don't see any way to salvage the entire thing in once piece at this point. Either the engine or the airframe has to go on the back burner, and it's the interest of the VC angels that decides which is which. "He who pays, says."

    Unfortunately, most people in Peter's position seem to double-down on their dream at this point, fearing that, if any part of it isn't perfect, the whole thing will fall apart. Which, usually, is a self-fulfilling prophesy in the end. If you've truly bitten off more than you can chew, your only options are spitting some of it out or choking to death.

    Hopefully Peter keeps a calm head, takes a step back, and thinks it through.
     
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