My Preposterous Fantasy Aircraft: The Luge

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Victor Bravo, Mar 7, 2019.

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  1. Mar 7, 2019 #1

    Victor Bravo

    Victor Bravo

    Victor Bravo

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    As the old rock'n'roll song "All the Young Dudes" by Mott the Hoople winds down, there's a wonderful lyric that sounds almost like an after-thought: "I've been wanting to do this for years..."

    Well, I'm taking the first tentative step, finally letting this oddball idea out of my head and into the strange, thriving world of public discussion on HBA.

    One of the ideas in my head that won't go away is a very small, inexpensive, minimalist E-ticket ride using a 25-40HP engine of some sort. A low wing miniature airplane with the pilot in a reclined or supine position. You guessed it... like riding on an Olympic Luge or small single place bobsled.

    This is intended to be smaller and more simplified than the Jeanie's Teenie, Watson Windwagon, etc. About the size of the Davis DA-11 but even less complex and probably slab sided for ease of construction. And probably even lighter. Like so many of the daydreams of experimental airplane enthusiasts, this idea started out as me trying to create a Cri-Cri size aircraft but with a single tractor engine on the front, and a more reclined pilot for drag and "fineness ratio" aesthetics. If the San Diego guys who did the Wee Bee pilot-lying-on-top airplane did something similar with the pilot reclined in a tub or trough... that's what I'm aiming for.

    Unlike the Cri-Cri it was always meant to be a simple and stress-free build. Colomban started with the idea of minimal engine power, something like 9HP per side. That drove a lot of the complexity and weight-reduction in the Cri-Cri. My goal was not to fly on 9HP engines, I'm willing to use the small block Brriggs engine (28-33HP) or the Polini 2-stroke (36HP). This will allow me to greatly simplify the build compared to Colomban's highly engineered masterpiece.

    My goal would be very simple flat-wrap sheet metal and pop rivet construction except for the main spar caps, which would be better off using AN rivets. The original idea is that this would not require tooling, molds, or messy composite fabrication, sanding dust, etc.

    One of the hoped-for parameters is that the fuselage would be less than 12 feet in total length, so the sides can be cut out of 12 foot lengths. The upper and lower wing spar caps for the one-piece main wing would be 12 foot lengths of aluminum angle. Add two 12 inch tapered wingtips, yielding a total span of 14 feet. I'm thinking something like 60 square feet of wing, with a decent but not exotic airfoil.

    My hope was to use a little cleverness and have a monowheel landing gear like the Monnett Moni. This saves weight and drag, as well as a little cost and build time.This is not an off-road big tire bushplane, it will be happily limited to reasonably smooth runways more or less the same as a club class glider like the 1-26, Ka-8, or L-Spatz.

    I've gone back and forth between an open bathtub/bobsled layout, a reclined sailplane canopy style layout (FFA Diamant sailplane / Monnet Moni), and the "open cockpit" with half-windshield (Watson Windwagon). This would be a fair weather "toy"; you'd fly it in conditions appropriate for a Quicksilver or Airbike.

    So with that description, I'd love to see any ideas, sketches, renderings, technical obstacles, and spirited discussions on this concept.

    PART of my interest in this rather exotic idea is based in actual real-world reality, believe it or not. I have a small space under the wing of my 172 in my hangar. Not enough space for a KR or Hummelbird. Enough for a Cassutt-sized airplane at best. So if I can come up with something cheap, small, and doesn't take too much time or skill to build safely, it could actually happen.
     
  2. Mar 7, 2019 #2

    rtfm

    rtfm

    rtfm

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    The HM293 is only 7.5ft long...
    HM293_plan_and_side_view.jpg

    Add a few feet for the engine/cowling, and some length for the rudder - my drawings came to 10.5 ft
     
  3. Mar 7, 2019 #3

    Victor Bravo

    Victor Bravo

    Victor Bravo

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    Not looking for a Flea type layout. RTFP :)
     
  4. Mar 7, 2019 #4

    Tiger Tim

    Tiger Tim

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    Sounds like you want a 3/4 scale DA-5.
     
  5. Mar 7, 2019 #5

    Victor Bravo

    Victor Bravo

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    This is a cardboard model of the fuselage I made a couple of years ago. The fuselage was designed to mount the small block V-twin directly to the flat area at the lower forward fuselage, this would have a couple of doublers or rails to spread the bolt loads out into the mounting platform.

    This version was going to use plug-in wings, hence the slots in the side of the fuselage for spar stubs like glider wings. The white parts are small plastic angles used to replicate larger aluminum bent angles. You can see the bent angles supporting the seat and the wing spar slots.

    The black part is simply a piece of foam picnic plate that I used for the forward part of the seat under the pilot's legs. I ran out of cardboard... no special structural reason for the black square :) The large hole in that part of the seat is for access to install and remove the wing spar pins.

    The upper and lower fuselage box skins have not been installed yet in this version. This design would require a full length bottom skin and a top skin behind the cockpit. Torsional movement of the forward (cockpit) area would be controlled by the main portion of the pilot seat bottom, which attaches structurally to the fuselage sides near the top of the fuselage. Large triangular gussets would be installedd behind the firewall and at the seat back to assist with torsional/parallelogram movement between the fuselage sides in the cockpit area.

    THIS version was going to be enclosed with a long canopy like the Moni.

    Luge Cardboard Model1.jpg

    Luge Cardboard Model2.jpg

    Luge Cardboard Model3.jpg
     
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  6. Mar 7, 2019 #6

    Topaz

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    So why not use that idea as a starting point? Enlarge the fuselage in width and depth slightly to accommodate the pilot laying "the other way", and work out from there. The finished thing need be no more complicated than the Wee Bee, and probably shouldn't be, to properly meet your requirement. Or, explicitly take the Cri Cri as "design fodder", and do a slightly deeper square-section fuselage that's a little bit longer to accommodate the more-supine pilot and puts the single engine in the nose.

    It's going to be a design-from-scratch effort regardless, so might as well do what you really want. But beware scope-creep. ;)
     
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  7. Mar 7, 2019 #7

    stevel

    stevel

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    How much more supine would you want beyond the cardboard model?
     
  8. Mar 7, 2019 #8

    cluttonfred

    cluttonfred

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  9. Mar 7, 2019 #9

    Victor Bravo

    Victor Bravo

    Victor Bravo

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    The Wee Bee was a triangular fuselage, the top was flat I believe, and the pilot laid on top of the flat side. So the fuselage would be a whole new thing. The Wee Bee was also technically a high wing or shoulder wing so the entire wing mounting system would be different. Essentially I believe their fuselage and wing mounting system is not worth starting with.

    The Cri-Cri with a reclined pilot and tractor engine is of course where all this started, but the Cri-Cri is a pretty complicated build, and the plans for it are death-penalty contraband here, and the engine mounting is different anyway. So although my bare canoe-stage fuselage may look similar to the Cri-Cri, it seems that there wouldn't be any deeper similarities than that. Besides, I am willing to build a little heavier than that aircraft, in deference to the fact that Colomban engineered every ounce out of that structure and I don't want or need to work that hard. I have more power available than he did, and I eat a lot better than he does.

    To answer SteveL's question, much more supine than the Cri-Cri, or Teenie, or Windwagon. About like this:

    Moni Supine Pilot.jpg

    I took another look at the Wee Bee's symmetrical or near-symmetrical airfoil , and flaps in Matthew's photo. I will have someone a lot smarter than me select an airfoil that is more suitable .
     
    Last edited: Mar 7, 2019
  10. Mar 7, 2019 #10

    MadRocketScientist

    MadRocketScientist

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    Are you familiar with the Colomban MC-30 Luciole? A simpler version of that might be along the lines of what you are looking at
     
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  11. Mar 7, 2019 #11

    cluttonfred

    cluttonfred

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    Perhaps I should have clarified that I was putting the Wee Bee forward as general inspiration and a conceptual place to start, not saying to build one. On reflection, you might take a look at the Ivanov ZJ Viera ultralight in its original monowheel configuration. Yes, it's composite, but it would give you a very good idea of realistic size/weight/power/performance for this concept. The fact that the monowheel gear was ditched for tricycle gear is also something to think about.

    1173541-large.jpg zj-viera.jpg

    ZJ-Viera

    General characteristics
    Crew: one
    Wingspan: 7.5 m (24 ft 7 in)
    Wing area: 9.1 m2 (98 sq ft)
    Empty weight: 77 kg (170 lb)
    Gross weight: 198 kg (437 lb)
    Fuel capacity: 12 litres (2.6 imp gal; 3.2 US gal)
    Powerplant: 1 × Hirth F-33 single cylinder, air-cooled, two stroke aircraft engine, 19 kW (26 hp)
    Propellers: 2-bladed wooden, fixed pitch

    Performance
    Maximum speed: 130 km/h (81 mph; 70 kn)
    Cruise speed: 110 km/h (68 mph; 59 kn)
    Stall speed: 44 km/h (27 mph; 24 kn)
    Rate of climb: 3.5 m/s (690 ft/min)
    Wing loading: 21.8 kg/m2 (4.5 lb/sq ft)

    https://en.wikipedia.org/wiki/Ivanov_ZJ-Viera

    I think that an all-metal design similar to but a little larger, heavier, and more powerful than the ZJ Viera would be good fun and find a market in the U.S. LSA/European microlight categories.
     
    Last edited: Mar 7, 2019
  12. Mar 7, 2019 #12

    Victor Bravo

    Victor Bravo

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    Yes, that is part of what I am trying to accomplish, but simpler and cheaper and a little smaller than the Luciole.

    Matthew I was not chastising you in the least, I was aware of the Wee Bee. I just already knew that it had a lot that I didn't want, but it is indeed the size and weight of what I am thinking about. I just want to feel much more secure, "strapped in", and enclosed. My experience flying the Kolb made it clear to me that I want to have some structure surrounding me, even if it is not 20G crash structure. The psychological aspect of it is what was surprising to me.

    The ZJ Viera is OK, I'd love to fly one, but I do want something a little more rocket-sled than that.
     
  13. Mar 7, 2019 #13

    MadRocketScientist

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    I like the idea! I don't have a copy of the Luciole plans but from what I have seen, while it is simpler than the CriCri but still a lot more complicated than say the DA-11.

    Watching with interest to see what you come up with.
     
  14. Mar 7, 2019 #14

    Victor Bravo

    Victor Bravo

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    The F-22 is simpler than the Cri-Cri :)
     
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  15. Mar 7, 2019 #15

    cluttonfred

    cluttonfred

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    I've got it! This, but not a jet and sitting the other way around....



    Only half joking, actually, as a much simpler unswept flying wing could work well for this mission, basically a ride-on-top version of the Fauvel-style Debreyer Pélican or Al Backstrom's powered WPB-1 straight plank.

    pelic_5.jpg Backstrom_WPB-1_Powered_Plank.jpg
     
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  16. Mar 7, 2019 #16

    Victor Bravo

    Victor Bravo

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    Oh yeah, I have definitely thought of those two aircraft a lot as well. The Pelican is in the "short list" with the Luge, the Jackrabbit (which became Fritz' Ranger), and a simplified Janowski J-5.

    The reason that I have discussed the Luge first is that it was simpler in some ways.

    The Pelican has fewer parts, but not that many fewer, and it would definitely need a drive shaft because the engines I'd use are too heavy to mount right at the trailing edge. So the torsional vibration and drive shaft issues would add some amount of complexity and time to an otherwise simple build.

    The Ranger is still of serious interest, but it needs some weldments for the cabane assembly, and it needs struts with all of those fittings, etc. Those parts are more fiddly than is absolutely necessary for a minimalist airplane. The Ranger needs folding wings to be kept in my hangar, and that takes some fiddling too.

    The Luge can be almost a one-piece airplane that doesn't have to be disassembled after each flight for storage, trailering, small hangar space, etc. That is probably the kicker for me. It would also be reasonably thrilling to fly due to the size, and perhaps even a little faster than my trusty old 172.

    But the mission for this thread specifically does not inclcude ride on top. There's threads for the flying motorcycle and other stuff that would address the ride on top desire. For this "mission", I want to be sitting inside something at least halfway. I want my butt, my hips, and some of my lower torso to be against the inside of the seat or the cockpit or the bathtub. I want to be able to roll the airplane 90 degrees wing-up and not fall out.
     
  17. Mar 7, 2019 #17

    cluttonfred

    cluttonfred

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    Hmmm...without the ride-on-top aspect and simply an open cockpit, this thread comes to mind -- Full-size Clutton Tadpole? -- especially a low-wing iteration like this.

    Big Tadpole (1).jpg

    Tailless makes it look racy, low aspect ratio for light weight, modest taper to avoid tip stall, tractor-mounted engine, seat the pilot on the CG.... ;-)
     
  18. Mar 7, 2019 #18

    TFF

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    I think you are missing it not going with the Teenie with the removable wings. Just take a little of the crude off of it. The best part of that plane is it is so buildable. The worst part, which you have covered, is it takes a decent pilot, not someone who just got his ticket. Making it look good would not be so hard.
     
  19. Mar 7, 2019 #19

    blane.c

    blane.c

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    CGS Hawk, Kolb Flyer, and Lazair are aircraft I would look to for ideas, because of there light weight and minimalist designs not because they fit your ideal exactly. You may be wanting trussed carbon tube construction with fabric covering, to get the look you want.
     
  20. Mar 7, 2019 #20

    Hot Wings

    Hot Wings

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    Looks like a Quickie tub, but with a single wing and no tail 'stinger'. Add a big flat wrap canopy and a Horizontal tail - and be done with the preliminary configuration design?
     
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