Raptor Composite Aircraft

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

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  1. May 23, 2019 #601

    canardlover

    canardlover

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    Marc, we have never met, looking forward to someday. The original vertical area concerned me from the onset and flight showed my belief they were inadequate. They were increased significantly in two steps and showed little improvement in stability. I was never a fan of BLENDED WINGLETS( there, I said it too) and suspected significant wrap around flow vertically up the winglet at high AOA , thereby compromising the flow over the winglet. That is when I figured a fence at the inboard point where the radius began should likely help . It arrested the dutch roll tendency, locking in the airplane when rolling into and out of banking. It also, not surprisingly, require adding significant amount of up elevator trim after their addition telling me the wing was now also producing more lift, again no surprise to me, and working harder. I then suggested we do stall testing and he scoffed at that and said everything is fine now , time to build the real one. So all bets are off as to how real articles stall behavior plays out. As I said , I have suggested many required test considerations, only to have them scoffed at. Don't like to throw hands up in the air but what else could/can I do. He thinks he knows it all.
     
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  2. May 23, 2019 #602

    BJC

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    The quote box mixed up two people’s posts.

    My part of that was “What is the current empty weight, and how much could it be reduced if redesigned?”


    BJC
     
  3. May 24, 2019 #603

    Marc Zeitlin

    Marc Zeitlin

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    I will echo that.

    Yep. Substantially reducing span-wise flow would be expected to have that effect. Glad to hear that the idea does work with blended winglets, and that putting them at the wing end of the blend is acceptable.

    One would expect it to be similar, if not identical, to the model's behavior. But obviously, only actual flight tests will tell.

    While I am certainly happy to have you comment on the issues that you, as an insider, have seen on this plane (and they certainly echo everything that any knowledgeable person here has said many times), I have to say that I'm surprised that with you posting your not very positive comments in public like this, that your boss hasn't asked you (and possibly your son) to find another means of employment :). Hopefully that means that he has no other choices, which would bode well for <at least relative> pay scales...
     
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  4. May 24, 2019 #604

    rv6ejguy

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    I watched all the videos and thought the model phase was rushed along while things were still being learned and problems still evident to be corrected. I was surprised when that was suddenly finished and full scale production started. Most of us know that testing often saves a lot of headaches down the road, not to mention time and money. I thought the same thing on the pressurization tests. It seemed close enough was good enough for Peter with no further test to target pressures.

    The DK Effect is strong here. Thanks for your insightful posts Jeff.
     
  5. May 24, 2019 #605

    pictsidhe

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    I haven't been following this project too closely. It looked a bit far fetched when I first came across it.
    Thinking that with no previous experience, you can easily beat the current state of the art seems a trifle optimistic to me. 'An SUV for the skies' makes me think that the raptor will be heavy, thirsty and lumbering. That is looking increasingly likely.
    I have dreams of building a seriously awesome transatlantic aircraft, but I need to spend more years gaining the knowledge to pull it off. As well as some easier stepping stone projects.
    A lot of possible features on my 103 are getting filed in the maybe-later folder. I can design/build simple parts now, maybe later I can develop my idea for a better one.
    It's taking considerable effort to do things relatively conventionally!
     
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  6. May 25, 2019 #606

    rv6ejguy

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    Peter was running the engine again and found the last time, the main engine drive belt had come off previously. This drives the water pump among other things. But he said he wasn't worried that the coolant "only" got to 250F. He spends a lot of time on this video discussing the belt tracking, insisting the belt length plays a main role there. No it doesn't. The belt is running off the edge of the idler pulley. Not correct. The pulleys simply are not aligned properly as people commented on the video. Power runs up to about 170 hp were done again which doesn't prove much.

    He did finally get a proper nose gear door actuation system built now. Good job there.

    Still aiming to fly to Osh. Does not seem that will happen as sanding work is still being done on the wings and cowling.
     
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  7. May 26, 2019 #607

    Voidhawk9

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    The end of the road is coming, can't keep kicking all those cans too much further.
     
  8. Jun 2, 2019 #608

    Tom Nalevanko

    Tom Nalevanko

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    Progress continues... Well sorta... Just bumping the thread a bit.

    Best,

    Tommy
     
  9. Jun 2, 2019 #609

    rv6ejguy

    rv6ejguy

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    The latest video shows a forgotten heater valve in the system and wondering why the a/c wasn't effective... Really? All that systems planning and this was left out somehow. I just see more and more weight going in on every video.
     
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  10. Jun 4, 2019 #610

    harrisonaero

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    After watching all the videos and following the project closely here are some observations from someone that works in the industry <former DAR, current DER> in an attempt to provide observations for the good of the forum which I’ve been a member for a long time (and RAH before that).

    · Kudos to Peter for taking the initiative to spend money he made from <apparently> selling his tech company and doing something new in aviation- it takes real guts to do that

    · It’s easy to be a naysayer from the sidelines when someone else is out there trying it

    · Nice job using CAD/CAM and CNC to make molds

    · Nice job providing regular updates, including ones that aren’t flattering, to gain an online following to fund your project

    · Converting a diesel car engine is a terrible idea… way too heavy plus you risk the strong chance that the engine manufacturer will send you a cease-and-desist letter for using their product in a way that gives them significant liability (deep pockets).

    · Use a proven engine for now and then wait for a properly sized diesel to be certified later. BTW aircraft diesels are VERY VERY hard to certify, even with tens/hundreds of millions of dollars of development money.

    · Spend a considerable amount more time flying the scale prototype with telemetery using a flight test DER to create test cards, analyze the video results, and review the telemetry data. I can recommend Len Fox (look him up in the DER directory or PM me). Plan to spend some serious time and money on this- it will pay off HUGE dividends later when testing full scale.

    · Build a bare bones-aircraft without any systems not needed for first flight. If it were me I would even build locked landing gear and fly that for the first 50+ hours. This saves you time, money, cost, and risk. Once you’ve fleshed out flying characteristics then start adding systems one at a time. BTW- design in systems first as you develop structure, just don’t add them until well into flight testing.

    · Using flexible control cables for primary flight controls like an ultralight, really? One word- icing. This is an absolute deal breaker for the design and I will be surprised if you can find a qualified flight test pilot that would be willing to take the risk.

    · Develop a very accurate and thorough W&B spreadsheet for each and every component so that you know exactly how to get to your weight margin goals.

    · Don’t plan to go to OSH this year. Take a step back, maybe take a two-week vacation, and really think about why your aircraft is grossly overweight and why you keep having problems with systems- especially firewall aft.

    · Hire a certified aircraft expert to go through your airplane in detail and then take their advice- certified planes are certified for a reason and small/big decisions you make now will pay huge dividends later in product liability, customer complaints, reputation, etc. BTW, I’m not pitching my services here- too busy working with other designs.

    · Be realistic. Few new clean-sheet aircraft companies succeed, especially those that aren’t run by aviation experts. If you think you can beat the statistical odds then you need to show why statistically. If you can’t show the odds then you need to change the game by hiring experts. Look up getting help from someone like Dieter Koehler- he can give you good advice (though like my observations above you may not like what you hear). If you’re serious about hiring him PM me and I’ll forward you his contact info.
     
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  11. Jun 4, 2019 #611

    rv6ejguy

    rv6ejguy

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    Agree. Most of this has been said before in this thread.

    No one can dispute Peter's drive and ambition on this huge and complex project but there are dozens or hundreds of gotchas on this design which have been discussed and clearly the prototype will not perform anywhere close to his projections with the massive overweight condition being only one of many reasons. Engine, PSRU, systems, control and stability remain major sticking points as well.

    He continues to burn through cash and is nowhere close to having a proven, viable design ready for production. I can hear his original optimism and drive fading somewhat in the last dozen or so videos as reality sets in but he still doesn't know what he doesn't know. As I said before, he wants to see it at least fly (at any cost seemingly) after all the work and money that has gone into this project.
     
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  12. Jun 4, 2019 #612

    BoKu

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    Wait, what? Push-pull cables? I missed that part. I've used them as a last resort for secondary controls. But for a primary control designed to Part 23 input loads, it just sounds like a way to add weight, expense, slop, and friction. Their only redeeming factor is ease of development.
     
  13. Jun 4, 2019 #613

    TMann

    TMann

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    Actually, I believe that comes from the Velocity design.
     
  14. Jun 5, 2019 #614

    Malish

    Malish

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  15. Jun 5, 2019 #615

    aeromomentum

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    Thielert/Continental and Austro make auto Diesel engine conversions that are popular, certified and practical if a bit expensive.
     
  16. Jun 5, 2019 #616

    rv6ejguy

    rv6ejguy

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    Unfortunately the Conti 4 cylinder engines are not powerful enough and the CD-300 V8 will apparently be $90,000+ and I don't believe has been certified yet nor is it available. It's still short on power for this design too. It would lack the altitude performance required at FL250 being only single stage turboed with a low critical altitude.
     
    Last edited: Jun 5, 2019
  17. Jun 5, 2019 #617

    canardlover

    canardlover

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    Joa
    You well know my feelings and position related to this project. But in fairness the control system is comprised of the following :
    Ailerons - they are a combination of traditional cable /pulley system in fuse connecting via final combination pulley/output arm to push/pull tubes in wing.
    Elevator - combination of push/pull, torque tube,and bellcrank. Kinda aircraft
    Rudders- this is where sheathed flexible cable is employed, however it is Rutan style tension only connecting to a bellcrank with a spring return and push/pull link to rudder itself.

    Hope your doing well my friend, say congrats to Isaiah !!
     
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  18. Jun 5, 2019 #618

    BoKu

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    Can you please clarify, when you say "push/pull" for the elevator, do you mean a Teleflex-style push-pull cable? Or do you mean a push/pull tube like an aluminum tube with rod ends installed at each end?

    Thanks!
     
  19. Jun 5, 2019 #619

    canardlover

    canardlover

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    Sorry Bob,
    It is push/pull tubular links and bellcranks in canard/foreplane. Push/pull sidesticks connecting to lateral torque tube linked vertically to longitudinal torque tube through forward cabin bulkhead linked vertically back down to bellcrank that connects to the lateral push/pull tubes oriented spanwise inside canard structure , yada, yada, ya !!!
     
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  20. Jun 5, 2019 #620

    BoKu

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    Oh, okay, I guess that's legit. As for the rudder cables, every modern sailplane, mine included, has steel cables running through nylon tubing. It's a simple, robust solution that solves a lot more problems than it causes.
     

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