Raptor Composite Aircraft

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

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  1. Mar 9, 2019 #501

    Andy_RR

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    If Peter pushes it outside and smears cow dung all over it, this metric should be within reach without endangering too many lives and while keeping costs to a minimum...
     
  2. Mar 9, 2019 #502

    anvegger

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    hat was the one of my points long time ago. But believe it or not we (software guys) have a solution for this program

    [video=youtube;B7MIJP90biM]https://www.youtube.com/watch?v=B7MIJP90biM[/video]
     
    Last edited by a moderator: Mar 20, 2019
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  3. Mar 9, 2019 #503

    canardlover

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    Amen to that observation.

    Given the lack of adequate testing of the engine/redrive combo, I have voiced a concern for the safety of the test pilot over and over again and recommended acquiring a used Lyc. 540 or Connie 550 and installing it to investigate and prove the aero design first . A suggestion not received well. Did you fall off the face of the earth again

    The engine/drive package due to its overcomplexity brings with it an insane number of potential failure modes that in my opinion far outweigh the advantages,if any, that it may or may not provide.

    I try very hard to strongly emphasize the importance of cautious,calculated,and responsible judgement needed in the test phase of an aircraft development program. Whether or not that advice is followed is out of my control.
     
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  4. Mar 9, 2019 #504

    Turbine Aeronautics

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    Jeff, I’m fairly confident that your advice to Peter would have unanimous backing from forum members. Over the last week or so since the last run of the engine where there was another minor leak from the gearbox, I have been strongly tempted to contact Peter with exactly the same advice that you have offered him, for exactly the same reasons. An engine failure at 200’ on the first flight would likely see an end to the program.

    At the end of the day, it’s the airframe and it’s performance that Peter needs to demonstrate and validate. The customers are not so concerned about the Audi engine, which is supported by the fact that we are having so many enquiries about our turbine engines from Raptor buyers, and many of our own delivery slot holders are Raptor buyers.

    From a purely selfish commercial perspective, I want to see this program be successful as I will then have 1500 potential customers for our future 300hp Turboprop. However, I am an enthusiast above all and Peter’s concept clearly has appeal which is demonstrated by his order book. I sincerely hope that regardless of what engine goes into the Raptor that the hopes and dreams of those that want a Raptor are not dashed when the prototype rolls itself up into a ball following an engine failure, and the program grinds to a halt.
     
  5. Mar 9, 2019 #505

    flyboy2160

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    You should restrict this sentiment to yourself. What do you mean? "Well, he's an arrogant, incompetent huckster who suckered money in with B.S. promises, but he's an OK person because he likes puppies and gives to charity? This level of arrogant incompetence IS a proper cause to judge him as a person.

    I'm not as concerned about a test pilot getting killed. If he's not enough of an engineer to sniff out the B.S. here, well he'll be a candidate for a Darwin award. Even though they'll have to fly at first far away from Disneyland, a bigger concern is people underneath this thing who never signed up to be endangered by this mess.

    This isn't 1904. Spare me the 'they will learn from this' positive spin. There is plenty of engineering knowledge available to have avoided this flying hype-mobile.
     
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  6. Mar 10, 2019 #506

    rv6ejguy

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    That has to be frustrating to work there under this sort relationship. At least you've said your piece here and many appreciate the clarity you've brought to this thread.
     
    Last edited: Mar 20, 2019
  7. Mar 10, 2019 #507

    Topaz

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    Accusations of malfeasance, fraud, or just plain ill-intent are best left to the appropriate legal venue, not this forum. If you don't have standing to bring such an accusation in court, you don't have any kind of moral standing to bring the same here. HBA's founder recognized this from the beginning, which is why this is included in the HBA Code of Conduct, specifically paragraphs 9 & 10. Probably something you'll want to read at a time of your convenience during the next minute or two.

    While there are certainly a lot of aspects to the Raptor project that are appropriately described as "questionable", what you're doing is attacking the person involved. You're welcome to do that on Facebook, on rec.aviation.homebuilt, or over a beer in your favorite establishment, but don't do it here. There's plenty of material in this project for technical discussion of the potential pitfalls and problems with the airplane and engine without resorting to attacks on the people involved, and the other members posting in this thread have managed to do so for over 500 posts. Theirs is an excellent example for you to follow.

    If you disagree, or want to discuss this off-topic issue further, I invite you to PM myself or any of the other moderators of this forum. Have a great day.
     
  8. Mar 11, 2019 #508

    gtae07

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    You're really dating yourself there ;)
     
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  9. Mar 16, 2019 #509

    rv6ejguy

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    In the latest video, it was good to see Peter replace all the welded aluminum bellcranks with 4130 ones. Maybe someone looked at my comments...

    Looks like they have 14.5 degrees of elevator up travel now so that seems better than the first design. Have to see what the control forces are like though with the linkage design.

    The intake scoop design gets heavier and more complicated all the time and it's completely unneeded. Controlling the outlet flow is easier, lighter and more efficient from a drag point of view. Lots of time wasted on this unfortunately. Should just use a fixed inlet.

    The strake fairing on the door looks like a bad idea but there is no other choice at this point. I think the door will change shape with pressurization loads and this will misalign the strake fairing with the rest of the wing, probably tripping the airflow. Don't see how this can be made to fit well in flight and still have the door open properly on the ground.

    Redrive bearing wear doesn't look good after a short time running. That will involve more time to fix again.
     
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  10. Mar 16, 2019 #510

    BoKu

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    So, still no IO-550?
     
  11. Mar 16, 2019 #511

    rv6ejguy

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    Looks like Peter didn't find your suggestion helpful on YT. The IO-550 doesn't fit the "image" of Raptor- modern, superior etc. He will see the Audi through to the end whatever that is... I will be a big blow if it doesn't work out as he dreamed.

    I've gone back to watch parts of videos from 2016/17 on the engine and turbos in particular. He certainly went down many wrong paths, done things over when they didn't work out and just doesn't understand either part very well. He's in for a dose of reality down the road when testing begins. Clearly he has no idea how a proper engine development program should be carried out. That is a full time and expensive task in itself, requiring people with a deep engine background.

    The redrive too- been apart and re-designed so many times, I can't count and still not looking good after only a few hours running collectively.
     
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  12. Mar 17, 2019 #512

    Voidhawk9

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    In the video previous to this one, when they took the engine off: There was a good view of the radiator wedged in front of the engine below the intercooler. No sign of ductwork to it at all that I could see, it appears there could be nearly zero flow through the radiator if nothing further is done.
     
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  13. Mar 17, 2019 #513

    canardlover

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    I described the importance and need for inlet vanes to him long ago to redirect airflow through radiator, will see if they get installed.
     
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  14. Mar 17, 2019 #514

    rv6ejguy

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    I've brought this up several times. No ductwork for any HXs and they are placed at obtuse angles to the airflow and stacked on top of each other. These things all guarantee ineffectiveness and high momentum losses(cooling drag). Some HXs are out in space like the oil cooler. All of this shows a fundamental lack of understanding about this very important aspect. I hope he listens to you Jeff now before he finds out nothing cools well.

    It's been shown over and over in testing that any small air leaks in the ducting hurts the Delta P across the HX or engine in the case of air cooled engines, and at the same time reduce mass flow through the system.

    When done correctly, you can get by with very small inlet areas and recover all the lost momentum across the HX as I proved on my installation. With cooling drag making up 15-20% of total drag, this should be a priority for any high speed design.
     
    Last edited: Mar 17, 2019
  15. Mar 19, 2019 #515

    Aesquire

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    While I'm not sure about anyone learning anything from this project they didn't already know, it does seem to validate a few of my opinions. But I didn't need another example of "untried engine in untried airframe equals low probability of success."

    I really do wish these guys luck.

    An anecdote on weight problems. Many airplanes have been heavy by as much as 25% over spec. Some very few designers are successful in clawing the mass back down.

    The Douglas A-4 Skyhawk is a great example of utterly ruthless dedication to keeping the weight off. The designer, Ed Heinemann, had a vision of a light, agile plane to fill a Navy requirement for a Carrier based bomber. The Navy's spec envisioned a plane 3 times the size ( feel free to correct me, I'm pulling these numbers from memory, and not looking them up ) that Douglas delivered.

    The list of innovations is long, as are the "luxuries" left off to get to weight. One such was the air conditioning system, that was delivered 84 pounds over weight by the vendor, who apparently figured Douglas would be desperate enough to complete the plane that they'd just take it. Nope. Douglas sent it back, with instructions to make it to spec or let them know they couldn't. Period.

    They got the product to spec. I'm sure there was back channel communication I haven't seen. But can well imagine.

    The ultimate product was quite successful, and is still in service. Amazingly in an aggressor role in dissimilar air combat training, and defeats F-15 & F-16s in serious competition. ( albeit with notional weapons.... Usually)
     
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  16. Mar 19, 2019 #516

    Vigilant1

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    I love the A-4, but let's not go crazy here. "Notional weapons" covers a huge issue: Load some AMRAAMs on an A-4 and it will NOT turn like a "slick" A-4. And the radar? Don't even go down that road. In a close-in fight? (First--shame on the F-15 pilot for ever letting that happen. But . . .) An A-4 can't hope to out-turn or out accelerate an F-16 or F-15. Really close? The twin 20mm linear cannons on the A-4 are no match for the rate of fire of Gatling-style 20 cannon on the F15/F16 (important for air-to-air work). And the Nellis situation is also highly artificial unless you plan on having your engagements within about 20 minutes of your home base. After you've hung enough bags of gas on an A-4 to go somewhere, it is still a capable light attack aircraft, but in the air-to-air role it is little more than a target drone in a modern aerial fight.
    Again, the A-4 is/was a great plane, and I'm not saying a USN A-4 Aggressor pilot never snuck in a successful AIM-9 shot on an F-18 (just as the USAF Aggressors flying F-5s could still teach the F-16 and F-15 guys something--given a lot of artificial advantages).
     
    Last edited: Mar 19, 2019
  17. Mar 20, 2019 #517

    harrisonaero

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    Since I work to certify aircraft as a day-job there are numerous things in this project make me just groan. But one thing's for sure, Peter is out there doing it with <probably mostly> his own money so you have to give him credit for that. And he's been transparent and consequently has opened himself to criticism. That takes some stones. Whether the project succeeds where nearly other clean-sheet aircraft startup has failed- yet to be seen and he seems like the kind of guy to keep at things.
     
  18. Mar 20, 2019 #518

    Aesquire

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    This is the third time my reasoned response took so long I lost it. :)

    Yes, with rational ROEs a modern fighter would make quick work of an A-4.

    Rational ROEs are not common in U.S. service since Vietnam. ( Rant Redacted ) In a training role, restrictive ROEs both set up realistic reflections of real world conditions and allow the use of lesser capable craft than the enemy craft simulated. In those, unfair, scenarios, A-4s are still defeating the best fighters we have. Admittedly usually flown by veteran retired instructors in civilian contractor planes.

    An A-4 with Sidewinders and loose ROE is vs. a F-22 with "Make visual identification, and get a selfie with the enemy" is much "fairer" than it should be.
    I am biased, A close friend was an A-4 avionics guy in the Marines.

    In any event, the point was the extreme efforts to save every gram during the development of the A-4, sometimes to the detriment of capability.


    But I've already complained about the Raptor, so thank you for your comment.
     
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  19. Mar 20, 2019 #519

    mcrae0104

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    They claim to have 1,500 deposits. Anybody know how much each deposit was? $1,000 maybe?
     
  20. Mar 20, 2019 #520

    Turbine Aeronautics

    Turbine Aeronautics

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    The majority of the deposits are in escrow from what I understand and Peter does not have access to those funds. He made the offer for some deposit holders to change their deposit to a larger one that was non-refundable and he has access to those funds. However, I believe that those deposit holders were incentivised with shares, so they will have become investors and will have accepted the risk involved. Peter has not been unethical in any way as far as I can tell.

    He is clearly a hard working, clever person and has my respect for that. He is trying to deliver a product that is clearly the dream of many. However, his lack of experience in this space and his reticence to heed advice has created some problems during his journey to develop this aircraft.

    I wish him well; I sincerely hope he can deliver; I hope no one is hurt along the way.
     
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