twin boom pusher plans

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by cheetah650, Jan 15, 2009.

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  1. Jan 16, 2009 #21

    Topaz

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    Honestly, most of them focus on the airplane and not the business. A solid business plan can carry a less-than-perfect airplane to profitability. It doesn't work the other way 'round.

    Most of the manufacturers get hung up on what a wonderful airplane they've designed and lovingly built, and expect that the "world will beat a path to their door." Guess what? It doesn't really work that way for mousetraps, either. You have to have a viable business model, great marketing, and sufficient funding to carry you through at least a couple of years without selling much of anything, while still paying for all your bills and all your rents, insurance, vendor purchases, marketing materials and appearances, employee salaries, and - oh yeah - your own salary to boot. That's a lot of money, and most people starting businesses severely underestimate their costs for that period - and equally overestimate their incomes.

    Marketing costs alone for a new large-product launch like this are going to be in the tens of thousands of dollars, at a bare minimum. Doing it right has you pushing well into the upper half of five figures. Most small manufacturers, when they hear that, decide to do it themselves or get their cousin's kid to "make up a web site" for them because "he's good with computers." Then they wonder why they're not getting any sales. Like everything else, you get what you pay for. A pro will focus on how to market your product, not just make a slick brochure or pretty web site.

    Orion has said all the rest of it here on the forums many times before. Starting a business takes a lot of planning, thought, and resources. Just having a great-looking airplane isn't enough.
     
  2. Jan 16, 2009 #22

    Mac790

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    I'm afraid that plans for that plane doesn't exist at the moment,
    Yes canard spoils visibility a little bit but it's still better than in conventional designs.
    I dont think that twin boom pusher looks like a"plane' either, I was thinking sometime ago about similar configuraion, but it's in my opinion really "ugly".
    I'm not familiar with his latest designs/projects (beside Space Ship One, Two) but for my knowledge he doesnt build pushers either. If you are looking for efficiency, you might try "conventional designs" like Polen Special, Nemesis NXT, etc.

    Seb
     
  3. Jan 17, 2009 #23

    Dana

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    If you want plans, seems you're going to have to compromise on something.

    Many of the pusher "ultralight like" aircraft have the visibility (I mentioned Kolbs before because I'm familiar with them, but there are others) but not the speed. There are some tiny fast single seaters with good visibility. But the ultimate, probably exactly what you want, isn't a kit, and not even a production aircraft any more--
    the Edgley Optica:

    [​IMG]

    (This should get the ducted fan freaks going, too...)

    -Dana

    Hangover: The Wrath of Grapes.
     
  4. Jan 17, 2009 #24

    Midniteoyl

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    now that is cool...!
     
  5. Jan 17, 2009 #25

    cheetah650

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    well this one is very close to what i am after. but it should naturally follow from conventional wisdom to place horizontal tail above the prop wash as it will generate a low pressure zone thus helping down lift. Placing it in the middle of prop wash is also logical as upwards deflected elevator will help for early rotation. But it's difficult to see the rationale behind placing horizontal surface below the prop wash. So I guess i am missing something. :ponder:
     
  6. Jan 17, 2009 #26

    Grimace

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    Since your twin-booms are one of your primary criteria, I won't bother mentioning an entire class of aircraft that meet every other one of your criteria... powered sailplanes...

    Sonex, Europa, Choucas, Alpin, Sirius, TST-6, TST-8, Soaring Gull, etc.

    What about a gyro? You can build on of those with twin booms pretty easily.... :lick:

    Too bad this is only a single-seater. For as silly as I think twin booms are, I really like the lines on this one...

    Sadler Vampire ultralight, Sadler vampire ultralight aircraft.
    [​IMG]
     
  7. Jan 17, 2009 #27

    Grimace

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  8. Jan 17, 2009 #28

    Dana

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    Yeah, the Vampire was definitely one of the coolest looking UL's ever built, and good performance too. Pity it's no longer being produced.

    -Dana

    A government big enough to give you everything you want, is big enough to take away everything you have. --Thomas Jefferson
     
  9. Jan 17, 2009 #29

    Mac790

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    It seems that someone is going to resurect it. Wish them luck with those prices.:)
    Sadler Aircraft

    Seb
     

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  10. Jan 17, 2009 #30

    Grimace

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    Oh I don't know that they won't find some buyers. To my eye, that's just about the prettiest LSA I've ever seen... and I don't even like twin booms...
     
  11. Jan 17, 2009 #31

    Mac790

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    It wasn't irony, I really wish them luck but for that money I would rather buy unfinished Berkut kit (pic 1) or maybe even new Zodiac 650 (pic2).

    In my opinion Gray's project looks much better but of course it's only project at the moment.

    Seb
     

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    Last edited: Jan 17, 2009
  12. Jan 17, 2009 #32

    orion

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    This aircraft has an interesting history, including being almost bought by the Chinese in order for it to be put into kit production. But for some reason everyone who was interested in developing it for retail sales either in kit or certified form, seemed to think it was covered in gold (the prices were downright ridiculous).

    The current configuration certainly has appeal (although it could use a bit of aesthetic work to make it less bulbous) but since the proportions have never really changed from the original, I'd have significant reservations regarding its yaw stability and ability to recover from a spin. Low aspect ratio tails tend to be relatively ineffective, even with significant areas so to me, this somewhat enlarged version of the original just seems to be a bit on the marginal side.

    Then, add to that the effect of the windmilling prop (blanketed horizontal) and the pilot just might be in for an interesting time, just when he needs to have everything working just right.
     
  13. Jan 18, 2009 #33

    bmcj

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    Here's a couple:

    This was one builder's solution to the BD-5 engine dilemma

    [​IMG]


    and this is someone's version of a self launch sailplane and a shortwing version of the same (Aircraft, www.ReactionResearch.com)

    [​IMG]

    [​IMG]



    It doesn't have to have twin booms to be a pusher. Have you seen the Woody Pusher or the Mini-Imp?

    [​IMG]

    [​IMG]

    PS - sorry about the size of the pictures.

    Bruce :)


     

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  14. Jan 18, 2009 #34

    plncraze

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    Orion,
    How far forward of the horizontal tail does the propeller have to be on a plane like the Vampire to keep the disturbed air coming from the windmilling propeller from disrupting the airflow on the tail?
    If a pusher propeller is close to the trailing edge of the wing will it disturb the air forward of the prop when windmilling?
    I am starting to see why tractor type engine installations are so common.
     
  15. Jan 18, 2009 #35

    Dana

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    The original ultralight Vampire was as cool looking as an ultralight can get... LSA is a whole different ballgame, not only are there a lot of sleek, attractive LSA's (not that I'd care to shell out the kind of cash they cost), the LSA Vampire somehow loses the attractive lines of the ultralight.

    -Dana

    Why is it called tourist season if we can't shoot at them?
     
  16. Jan 18, 2009 #36

    orion

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    Actually, quite a ways. This is why many airplanes that use this configuration end up with rather sizable tails or learn to live with the limitations. I remember when Powers and Bashforth were developing the MiniMaster - it was discovered that with the aft engine windmilling the airplane had to come in quite fast to land otherwise it didn't have sufficient elevator to flare. Given that that particular airplane was initially somewhat nose heavy, this resulted in a relatively high landing speed. The standard procedure became to either stop the prop or keep a bit of power on into the flare.

    And the same holds true for the full sized 337 as well as virtually all the airplanes that utilize this configuration.

    The trick then is to come up with a combination of distance and position to minimize this effect. Personally, I like putting the horizontal on top of the verticals, preferably above the prop disk. While that does not necessarily totally alleviate the problem (at high aoa you still get a bit of blanketing), it does tend to be much better than putting it directly aft.

    Putting it below the prop disk is generally considered to be a better approach but rarely does that deliver an attractive configuration (at least to my eye).

    I've never seen any evidence of this phenomenon but it might be argued that due to the flow's compressibility (things can be felt upstream), the windmilling prop might (heavy emphasis on the "might") trigger a slight level of boundary layer instability on one side of the wing, causing early and non-symmetrical separation. But as I said, I have not seen any direct evidence of this behavior.
     
  17. Jan 19, 2009 #37

    cheetah650

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    I fell in love with MiniImp when i first saw it. Those people need to understand that market for single place aircraft is very limited. It's against human nature. One of the most fundemental human instincts is sharing good moments and excitement with a loved one.
     
  18. Jan 19, 2009 #38

    Blackhawk

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    Plans and plane still for sale. US$19,000

    The drawing is what we had intended to redesign the fuselage to, if we had kept the project.

    The wings are swept back 16 degrees.
     

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  19. Jan 19, 2009 #39

    bmcj

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    I absolutely agree! I think that is one of the reasons that the EAA Young Eagles program has been so successful.

    Bruce :ban:
     
  20. Jan 20, 2009 #40

    Grimace

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    Most definitely. But you also have to keep in mind that there are experimental airplanes... and then there are EXPERIMENTAL airplanes. From the looks, it seems as though the Mini-Imp was of the latter category. Some planes should be kept single place.. at least until the kinks are worked out of some of the more difficult areas. Curtis didn't start with the Pitts S2. Van didnt start with the RV6. Rand Robinson didn't start with the KR2. And all for good reason!

    I think it makes a lot of sense to start with single seat planes. If the demand is there for a single seat, you can be very confident that a two seater will garner even more attention... not a bad position to be in... much better than having a marginal unproven 2-seater to start out with... the Lancair excepted of course... ;)
     

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