Making a boom, before Boom Aerospace - Messing around with breaking mach.

Discussion in 'Hangar Flying' started by nerobro, Nov 3, 2017.

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  1. Nov 4, 2017 #21

    TFF

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    Migs are cheap on the open market, but I think getting a DC-8 is the best idea. That way you can take all your friends.
     
  2. Nov 4, 2017 #22

    bmcj

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    Or if you had a big enough rocket, you can leave the wings off and launch vertically, then land under a parachute (albeit a very strong one that can survive a high speed deployment).

    Side note: SpaceShipOne was supersonic, yet was not terribly sleek or pointy.
     
  3. Nov 4, 2017 #23

    Lucrum

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    Forgetaboutit

    Driven by a IC engine? Forgetaboutit


    There's more to it than that. The airflow to the engine has to be slowed to subsonic speeds, usually through controlled shockwaves.

    IMO ........NO!

    Yes, either a pure turbojet or very low bypass turbofan
    And what's more, if it's not oversized you'll also likely need an after burner
    You'll need to factor in the temp rise and skin temps on the leading edges
    Absolutely
    Without even crunching numbers, I'd plan on a much higher stall speed.
    Some form of delta with a tail would probably be the easiest approach.
    But certainly not the only one

    Tandem You're goal is so far out of reach to begin with why make it harder with more drag area?

    I don't think the area rule would apply to the internal section of the engine intake
    You will want to apply it to the fuselage shape though.

    You'll also need to study compressibility and possibly high speed instability
    You'll probably want an experienced aerodynamicist on speed dial as well

    0.98 Mach indicated is the fastest I've ever been
    But that was in a $4,000,000 twin turbofan engine aircraft built by Dassault
     
    Last edited: Nov 4, 2017
  4. Nov 4, 2017 #24

    Autodidact

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    I'd like to see someone replicate the Miles M.52, which was a better and more sophisticated overall design than the Bell X-1 IMO:

    109_0940.jpg
     
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  5. Nov 4, 2017 #25

    BBerson

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    Is a permit required for each rocket launch? Kinda makes a hamburger run a bit of a pain.:gig:
     
    Last edited: Nov 5, 2017
  6. Nov 4, 2017 #26

    Aesquire

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    Recovery by skid, parachute, dry lake bed... etc. Is what you do when you have millions of taxpayers to pay for a marginal airplane.

    The Me-163, for example needed specialized recovery gear, 2 separate fueling/defueling trucks, ( so they wouldn't explode, like the airplane often did ) and had to land back at it's own airfield, or be abandoned to be hopefully picked up later. Not often, because if it just sat around without maintenance, it would probably explode from residual fuel.

    In short, don't make your life hard by not having landing gear, and avoid solutions that include, "Great! if we can just keep it from exploding".

     
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  7. Nov 5, 2017 #27

    Topaz

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    Double points for the Real Genius reference. :gig:
     
  8. Nov 5, 2017 #28

    pictsidhe

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    Can anyone think of a really small supersonic aircraft? Not including balloonists... The Fairey Delta 2 might be worth looking at. single RR Avon (how many engines do you want to feed?), capable of supercruise, or 1300+mph. Range 830miles. Seems ideal for $10,000 hamburgers? Oh, yeah it's also very pointy! I think that trying to do your own supersonic aerodynamics may be a bit optimistic. Plagiarism seems a really, really good idea here. Supercruise also seems a really good idea if you want to be supersonic for more than 40 seconds per refuel.

    Gfd2-2.jpg
     
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  9. Nov 5, 2017 #29

    BBerson

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  10. Nov 5, 2017 #30

    Hephaestus

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    Lol.

    Actually wouldn't a spitfire be a good starting point? .92 in an emergency dive.

    NACA actually had some neat papers on the theory of going supersonic with a prop.
     
  11. Nov 5, 2017 #31

    Topaz

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    The really big issue here is that, given you had a supersonic homebuilt, you couldn't fly it that way. FAR's strictly forbid it outside of a very few MOA's and military restricted areas. There's no waiver you can get, no special permit, and no class of "experimental" that makes it possible. The only non-military exception I can think of is Scaled's SpaceShipOne, and likely the only reason they got it was because the aircraft was going straight up and no sonic boom would ever reach the ground.

    It's all well and good as a fun thought exercise, but to what end?
     
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  12. Nov 5, 2017 #32

    Riggerrob

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    Options:

    Engine - The least expensive answer is a low-bypass jet engine already in production.
    The second option? If you have to ask, you cannot afford the development costs. Hah! Hah!

    Propellers - Skyshreak's biggest problem was that it's propeller was constantly exposed to supersonic airflow before it even started turning.
    Perhaps if you mounted the propeller(s) farther aft and used area-ruling to reduce boundary layer airflow to sub-sonic .... Imagine a 21st century version of the area-ruling applied to Convair F-106 with props turning aft of the wing.

    Ducted fans - are most efficient when hovering and their advantage decreases with speed.

    Drop tanks - are used to compensate for poor conceptual design. They are very draggy and far more difficult to design than conformal fuel tanks.

    The greatest opportunity for innovation is in nose aerodynamics. Adjustable BOOM technology is just a crude first step. Perhaps a Soviet high-speed torpedo can provide inspiration because it ejects a bubble of air around the nose of the torpedo. That bubble prevents the solid nose from touching supersonic water. The next aerodynamic step uses surface layer sucking and blowing to artificially tune nose shape for the gentlest sonic boom possible.
    Reviewing nose inlets on F-100 Super Sabre and Mig-21 could help us better understand supersonic airflow around noses. Did F-100 suck enough to disrupt the sonic shock come originating at the nose?

    Yes. I know that I ask too many embarrassing questions, but my goal is to encourage you guys to think up redneck-engineer solutions to problems that have stumped degreed engineers for decades.
     
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  13. Nov 5, 2017 #33

    bmcj

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    It’s been awhile since I’ve been up close and personal with it, but IIRC, the X-43 is only about 10 feet long and it is hypersonic.
     
  14. Nov 5, 2017 #34

    pictsidhe

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    How far do you go to get into international waters, 12miles? Anyone for a quick island break?
     
  15. Nov 5, 2017 #35

    pictsidhe

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    Cockpit is a little on the small side.
     
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  16. Nov 5, 2017 #36

    gtae07

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    Well, technically...


    So, if you can show that a sonic boom won't reach the ground, you can apply for the waiver. And you can apply for a waiver for purposes of determining that.

    The problem is that there's no specific definition of "sonic boom". The "low boom" designs currently being proposed would reduce the audible signature of that boom to being something like a car door closing. I've been in an acoustic simulator that can reproduce the boom from Concorde and an F-18, and the predicted "low boom" aircraft. The latter is hardly noticeable. But until the restriction is written more in terms of a measurable threshold rather than just any boom signature at all, it's essentially impractical.

    Of course, I live within hearing distance of an artillery range that likes to practice at night. So my threshold for annoyance may be different than someone else's.
     
  17. Nov 5, 2017 #37

    Swampyankee

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    How supersonic do you want to go?

    If the speed is less than about M=1.4 to 1.6, a simple, fixed-geometry inlet like the F-16 uses is practical.

    The powerplant is going to be difficult. The two most likely to be practical are the Adour, from the SEPECAT Jaguar and the J-85 from the F-5/T-38. I believe the Adour had to pass bird shot tests, so that may be a factor. It's also a low-bypass engine, so it's more fuel efficient when not in afterburner.

    Flight controls will be a major pain; it will have to be irreversible hydraulics.
     
  18. Nov 5, 2017 #38

    BBerson

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    Perhaps a very small single place EA-B with the pilot prone in a tight pointy tube could have a minimal sonic boom?
     
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  19. Nov 5, 2017 #39

    Aesquire

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  20. Nov 5, 2017 #40

    Himat

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    There was at least on long thread about the same subject a few years ago here on HBA. To find it, well.

    For inspiration on a small supersonic airplane, the Folland Gnat and Saunders-Roe SR53 come to mind. Restricting the speed goal to Mach 1,4 to 1,6 make design easier, both the jet engine intake and heating of the airframe. Actually studying the Folland Gnat is a good exercise as the plane was quite clever packaged.

    Small supersonic airframes have been made as both target drones and recognition vehicles. The USA made was smaller than their Soviet counterparts I think.
     

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