single seat, composite, ultralight STOL - would you like it?

Discussion in 'Bush / Float flying' started by Birdman100, Jun 1, 2015.

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  1. Jun 1, 2015 #1

    Birdman100

    Birdman100

    Birdman100

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    Imagine a small, very light, single seat all carbon fiber pusher STOL. It should be open cockpit (wind in the hair), with flight feeling similar to this shown in this VIDEO, but powered and STOL! Something you could jump to the friends barbecue with and land in its backyard drink a few bears :)ponder:) and back home.

    Built in composites, should mean it would be nice shaped and cute, with some nice lines, apart from todays boxy STOL planes. If it is STOL it doesnt need to by ugly does it.

    it would be taildragger naturally, with the option for tricycle and FLOATS!

    So, would you like to possess and fly one? What would you like more for that (hypothetical) plane to has and to be like?
     
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  2. Jun 1, 2015 #2

    Birdman100

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    additional info:

    *ultralight category
    *empty weight - less than 90kg (<198 lb) - yes, it is possible!
    *MTOW - 200kg
    *engine: two-stroke PPG 35 HP - in pusher configuration.
    *instruments: only basic engine (temp) + Flytec
    *landing gear: very robust - "Highlander" type
    *stall sped: 40kmh
    *cruise speed 70-80
    *Vne 150
    *visibility: exceptional
     
  3. Jun 1, 2015 #3

    BJC

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    Have you been peeking at my sketches? Think of an open cockpit J-5 with a bigger wing and a bigger engine. No training wheel for me with this configuration, because without the pilot on board, it will sit on the tail anyway. I haven't considered floats, but that sure is interesting.

    The FAA actually tested the effect of alcohol on piloting ability, and found that a small amount actually improved piloting skills. And I know for a fact that in the evening, after a few drinks, my neighbors become better pilots than they actually are during their actual flying.


    BJC
     
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  4. Jun 1, 2015 #4

    autoreply

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    No.

    I've worked on the Sirocco NG, which is pretty close to what you describe. Some lessons:
    *You need a windscreen to be able to fly out of the desert. Windscreen makes 80-100 km/h cruise at jacket-weather perfectly fine.
    *Too low wing loading means limited to weather conditions.
    *Too low wing loading means a much more challenging structure.
    *A light structure is fragile.


    If I were to go this route (not my preference though) I'd take the Sirocco and:
    *Make it a taildragger.
    *Move to a direct-drive and heavier 4-stroke to lower cost (half-VW comes to mind, as do direct-drive industrial engines)
    *Integrate engine in pylon, like on the Strojnik and Carmichael designs.
    *Reduce wing area to 5M2, composite skin and keep a high span. Change elevator to composite skin, same for rudder.

    Eduguessed specs:
    *Empty: 120 kg (that's real empty, with a BRS, instruments, battery, fluids; a flying plane)
    *Wing area: 5 m2
    *Span 9 meters, with both outboard 2 meters folding
    *Stall 38 kts typical
    *35 hp
    *Cruise, 80+ kts WOT
    *Climb, over 1000 fpm WOT



    It's a complete myth that "STOL" aircraft need extremely low stall speeds. I've flown sailplanes in the most disturbingly short fields, never the least of a problem. All of them are north of 40 kts dirty. Drag control (plain flaps for such a design) and good power/weight are far more important.
     
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  5. Jun 1, 2015 #5

    Birdman100

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    Oh, definitely! With spy
    drone! :roll:

    Yes, though, with composites I think we can do much better today!

    Something like this:
    1469990.jpg Seeker_1.jpg

    but with open cockpit, and more robust landing gear. And perhaps without struts (free cantilever wing)
    one sexy ultralight stol, and at affordable price!

     
  6. Jun 1, 2015 #6

    BJC

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  7. Jun 1, 2015 #7

    autoreply

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    I would have the one-piece wing on top and have separate flaps and ailerons, since you need them for decent approaches.

    Single wheel might be problematic in high bushes. V-tail makes a lot of sense here due to a vastly simpler structure (and a single mold or hot-wired cores)
     
  8. Jun 1, 2015 #8

    cheapracer

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    It's been done to death for cars including Mythbusters. Up to 0.03% alcohol levels, your driving skillz actually improve without any doubt. Starts to go back down a bit after that and after 0.05% goes down exponentially.
     
  9. Jun 1, 2015 #9

    Birdman100

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    Yes, Sirocco resembles what I want.
    wind screen would be optional (for desert "operations"). But 90% or more of these planes would never see desert. However it would be no problem nor any additional modification needed to fit windshield.

    yes, gusts and so on... Exactly like you added later, it doesnt need to be that low loading! 5m2 is perhaps too low for what I want, but something like 6.5-7m2 would be ok.

    empty can be lower (I consider empty without fluids) 100 kg max, for a plane I want. Your wing is, however to slender, 9m span, 5m2 area is ridiculous for STOL (aspect ratio 16!, sorry I mean stol - with the look of stol as well, not a sailplane. That is 0.5m chord, to low Re for a good Clmax).

    Sirocco wing is large and clean, I thought about smaller wing but more efficient in terms of "high lift", equipped with high lift devices - fowler slatted flaps, fixed or automatic slats and/ or VGs.

    Yes, but for my taste 38kts is too much for a STOL I want. 20-25 kts is the way to go - true STOL, with large flaps and a lot of drag for steep approach.

    Thank you for your inputs!
     
  10. Jun 1, 2015 #10

    Birdman100

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    I thought about one piece wing. What do you think how to attach it to the pylon best? 4 bolts?
     
  11. Jun 1, 2015 #11

    Birdman100

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    Oh, that! I thought you meant J-5 cub..
     
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  12. Jun 1, 2015 #12

    Birdman100

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    OK, some more clarification:

    I dont want "sailplane-looking" STOL. Something that is still STOL-looking plane, but with restyled lines and shape, as it can be done in composites.

    High wing is mandatory. Open cockpit (with optional for windshield) is mandatory.

    All composite skin structure. Fragile? Well, ok. That is why it is STOL, to land on a small strip and not to catch a bush or a tree. With wing area of 7m2 (wet cc 15 m2), fuselage wet area of around 5m2, it can be very light structure in composite sandwich.

    The idea is two-stroke PPG engine as it is both cheap and light. Reliability sucks I know. Any idea for a 35 hp 4-stroke but light engine? Light means 20-25 kgs for a 35 hp max!
     
  13. Jun 1, 2015 #13

    autoreply

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    You need the wind shield when you're NOT flying in a desert (for otherwise your balls freeze off) ;)
    Is that so? Note that I assume a 4-stroke engine, despite direct drive that's 40 kg for the whole package (prop, fluids, engine mount, the lot)
    80 kg structural gives a little bit of margin to exactly avoid very expensive or very fragile construction.

    See the Cri-Cri for what to avoid.
    Nope. Realistic difference to twice the chord is below 5% difference. STOL is the category (next to sailplanes) that benefits most from a high AR. Stall speed is mostly irrelevant, but climb angle (and thus speed) are crucial). With your typical STOL short wing, you're pissing away a lot of power simply to overcome the induced drag of a short wing.

    On top of that, a fully skinned, narrow chorded wing can be built way lighter than one with a bigger chord.
    Don't bother. Lowest stall speed is nice for showing off. In the real world, a double fowler flapped big wing gives you such a low L/D max that you don't want to use it for landing and it drags you down on take-off.

    This is what 38 kts stall speed looks like. That green wheeds on the right was a road .5 meter taller:
    [​IMG]

    Large flaps are essential. But I wouldn't go near those stall speeds. Way to sensitive to turbulence and it doesn't buy you any shorter strips you can get in.

    Say 50 kts lift-off @ 38 kts stall.
    With a half-vw, that's 50 meters of roll (3.75 m/s acceleration). You need another 100 meters to climb over the first three. Slower speeds will only give you a marginally better ground roll and climb angle.

    3 bolts. Torsion loads (yaw on the wing) are fairly low. See the Mü31 for ideas.
     
  14. Jun 1, 2015 #14

    bmcj

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    Well, then, to be really safe, shouldn't he drink the beers BEFORE he flies to his buddy's place? ;)
     
    Last edited: Jun 2, 2015
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  15. Jun 1, 2015 #15

    Birdman100

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    in the place I live summers are exactly like in desert - its already 30+ Celsius. OK, tip from you: windshield and/or balls insulator - accepted!But then, mornings and late afternoons when weather is calm for flying are not that hot.
    then we are at same structure weight. Though I really want to find the way not to give 40 kg for the engine package - it should be lighter!
    that is true, however I think you went too far with 9m/5m2 wing for this plane. This is just a chit chat but eventually numbers will tell. In this preliminary talk I appreciate your ideas but I have particularly design in my head (and sketches) that am not willing to change drastically. Well, we all know that you are "sailplane-infected" after all ;).
    Yep, but cant find any details for wing attachment. Isnt it like in all sailplanes - bayonet?This is close to what I meant, infact this is older-preliminary non-finished 3D model that STOL. Notice the place for horizontal tail (it was T-tail, but eventually changed to classic). Landing gear is going to be changed to "highlander" type, and that parasol struts to composite pylon. Imagine a small nose beam where pedals are going to be attached.

    1.jpg
     
  16. Jun 1, 2015 #16

    BJC

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    Nope. Drink at buddy's place because buddy provides the beer.


    BJC
     
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  17. Jun 1, 2015 #17

    Birdman100

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    One more thing (inspired with the last BJCs comment):

    there will be no large space for payload! For a survival kit only: first aid, a knife, hennessy hammock (yes, in a fashion of Bear Grills!) - a bottle of water or... beer.

    and a small fishing rod - it can be mounted below belly or wing

    some inspiration...

    picWilgaMosquitoHammockTwin.jpg
     
  18. Jun 1, 2015 #18

    BJC

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    It's 84 F here right now, no desert, not cold in the winter, don't need a canopy except for drag reduction.

    I want the LE at eyeball height, large span single slot flaps, long chord, short span ailerons, 4 cycle pusher.


    BJC
     
  19. Jun 1, 2015 #19

    autoreply

    autoreply

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    Count on a 4-stroke. That doesn't exclude putting a 2-stroke on there, but if you reconsider (like many people) and later want to go 4-stroke... you better took it into account in the inital design.
    It's not "liking" or anything like that. Do the math and see how much lighter a longer wing is and how much less power you're pissing away in drag during climb ;)
    wing-fuselage-intersection.jpg
     
  20. Jun 1, 2015 #20

    Himat

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    The weather is all about where you are. Around where I live it was 8 C down at the fjord. Higher up it was snowing, actually quite a few mountain roads closed due to snow on what in the calendar is defined as the first "summer" day. The density altitude on the other side is great for flying.
     

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