Flying wing as cheap and simple option for basic fun flying.

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Hot Wings, May 18, 2017.

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  1. May 18, 2017 #1

    Hot Wings

    Hot Wings

    Hot Wings

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    And with this comment another new thread is born. My intent is a continuation of the VP-21 and Flying Motorcycle of the Air related threads but focused on only the flying wing option as a solution. For the purposes of this thread lets define a flying wing fairly loosely.

    It can be any combination of:
    Flying plank
    Swept wing, either positive or negative
    It can have a defined fuselage
    It can have vertical surfaces for yaw control
    It can have external control devices - such a junkers style flaperonl/elevons.
    It can be a pusher or a tractor
    It can be a BWB

    Based on the other threads like this it should also be/have:
    Easy and cheap to build
    Build-able from plans or CAD files yet possible to produce in kit form for a 'reasonable' price
    Trailer-able and/or capable of being stored outside
    Large enough to fit an average US male
    'Reasonable' performance
    Not weird looking or intimidating to a pilot or non-pilot

    ============
    Let the Idea tossing begin :ban:
     
  2. May 18, 2017 #2

    cheapracer

    cheapracer

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    Well I've had a good look at the Opal up close and personal, must be one of the easiest planes to build going.

    I can cross over just about everything I've done in recent months to make these simply and dirt cheap.


    sad opal 1.jpg
    sad opal 2.jpg
    sad opal 3.jpg


    CoG is a big problem though, needs to be perfect for every individual pilot, maybe some mini canards at the front could resolve that some at the minor expense of drag.


     
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  3. May 18, 2017 #3

    cluttonfred

    cluttonfred

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    Maybe a movable seat and the main wheel at little ahead of the aft CG limit? If you fall on the tail from level then you're too far aft.
     
  4. May 18, 2017 #4

    Victor Bravo

    Victor Bravo

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    OK, I'll jump in too...

    Hot Wings' list of parameters includes cheap and easy to build. I say sheet metal for several reasons.

    It's probably less than $1000 in raw aluminum material for the airframe.
    There are more people today who are comfortable with a pop rivet gun than with woodwork (that would represent a big change from 20 or 30 years ago).
    Finishing cost can be zero for a plain Jane aluminum airframe if cost is a deal-breaker.
    Sheet metal is very easy to inspect for workmanship, damage, etc. both near-term and long-term.
    On this particular aircraft it can be executed without any flush riveting, dimpling, countersinking, etc.
    If it were worthwhile aerodynamically the D-tube can be dimpled and flush riveted, but with the Fauvel airfoils I rather doubt it is worthwhile.
    The engineering for sheet metal construction is very straightforward for an engineer - no variations in the allowables for Aircraft Spruce vs. Home Depot wood, grain density and direction, greasy fingerprints and amateur glue joints, Resorcinol clamping pressures, etc.

    Most importantly, if you can get away with fully sheeted wings instead of fabric, the airplane can be tied down outside with less degradation. than plastic or wood.

    OK.... Kevlar jacket is on.... fire away :)
     
  5. May 18, 2017 #5

    Victor Bravo

    Victor Bravo

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    That is an excellent technique, I believe it has been used by Mike Sandlin. If the BUG or GOAT does not fall on the nose when you sit in it, it is not safe to fly.
     
  6. May 18, 2017 #6

    Hot Wings

    Hot Wings

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    Envious!

    A very good example of where I'd like to see this thread go.

    Cg is going to be a problem for any of these small pusher wings. Marske was/is? experimenting with movable ballast.
    I've worked the numbers on a small canard and it is a viable idea. But it's another part to build and maintain.
    The stick free instability the Opal has might be easily fixed with a "sparrow strainer" trim tab like used on the Q-2/200.
    I know VB likes sheet metal and that isn't compatible with the nice curves of the Opal fuselage but a glass shell and angle aluminum substructure (like the prototype BD-5) should be just about as simple as flat sheet and rivets.
     
  7. May 18, 2017 #7

    Riggerrob

    Riggerrob

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    Verhees Delta is the closest to the OP's description.

    I favour a delta wing because it has the longest root chord which dampens pitch sensitivity and provides thick root ribs, all the better to hide the pilot.

    A pusher delta might work if all the control surfaces are outboard of the prop arc.

    Designing a small flying wing requires completely re-thinking aerodynamics because of smal Reynolds numbers. Facetmobile is a good example of a vastly simplified small flying wing/delta. Rumour has it that a flock of new Facetmobiles is being built by an EAA Chapter in Oregon.
     
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  8. May 18, 2017 #8

    cheapracer

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    The Wintons realised they chose the wrong airfoil, the models they sold had a revised airfoil and fly "beautifully".

    [video=youtube;_wEUSnF_wpc]https://www.youtube.com/watch?v=_wEUSnF_wpc[/video]
     
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  9. May 18, 2017 #9

    Hot Wings

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    No reason it can't be fully sheeted, or at least the top side. That is unless you want one version to remain part 103 legal - which is something I personally would like to see.

    My personal preference is for composites, but I have to agree that for mass market appeal sheet metal is probably the ideal for a combination of plans built and kit supplied parts. For a full factory built part 103 then composites might be the winner. Either way a composite fuselage shell just makes things look right. Find a way to do that in sheet short of stretch forming and I'll be a supporter.
     
  10. May 18, 2017 #10

    BJC

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    I have nothing against the Delta or any other flying wing type aircraft, and I realize that aesthetics are in the eye of the beholder, but it will be a challenge to meet the "not look weird" criteria for any the configurations being discussed.


    BJC
     
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  11. May 18, 2017 #11

    Aerowerx

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    Are you aware that there is already a thread for the discussion of flying wing design?
     
  12. May 18, 2017 #12

    Hot Wings

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    I don't think there was anything 'wrong' with the airfoil, but a different one might be better for a recreational version. Models don't have to worry about a stick free stability mode because the servo is always attached. Without a trim tab on the elevator, or some spring trim system any flying plank will exhibit the same stick free pitch instability.

    The big white tab at 9-11 seconds:

    [video=youtube;ZYVwr5SpS5M]https://www.youtube.com/watch?v=ZYVwr5SpS5M[/video]
     
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  13. May 18, 2017 #13

    Hot Wings

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    Yes, and I read them too. ;)

    But they are far more theory and academic than I'd like to see here. This one should be tightly focused on style, inexpensive, quick to build, and practical. No debates about the merit of ESLD, BSLD, Prandtl-D and other such 'trivia'. Nickel and Wohlfahrt need not contribute. :gig:
     
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  14. May 18, 2017 #14

    Victor Bravo

    Victor Bravo

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    There was of course a composite version of the Pelican, JCD 03 or 04 if I recall. All rounded and glider-like, with a beautiful blown sailplane canopy. Just adorable.

    But as has been discussed ad infinitum already, the cost of molds and everything that goes with it must be considered in the "cheap" aspect of this. Autoreply has steadfastly maintained that composites are cheaper and faster in a production environment, and he's far more qualified to talk about that than I. But this is a homebuilt airplane, not a production airplane, so that skews the equation a little. More importantly, the time/effort/cost/space/infrastructure for the person or company making the kit (assuming that there is a kit) strongly favors flat sheet metal instead of a molded fuselage.

    Imagining myself as a potential manufacturer of kits for this aircraft (where's that Ferrari dealerhsip?), the first thing that I can see is that with sheet metal, I don't need any manufacturing space with molds, vacuum pumps, rolls of bleeder cloth, buckets of resin, etc. I simply have the raw materials shipped from the metal supplier directly to the CNC / waterjet shop, hand them a thumb drive with the cut files, and they tell me to come back Thursday with the truck and a check. I tell them they can even keep the scrap aluminum, and they make a few extra bucks on it for beer money. So I don't even have to use the truck to haul away the scrap.

    So even at the very beginning, and even with all other factors in material cost or design considerations identical, I've already saved X amount of floor space, monthly rent, etc. by not having to have or store tooling. My main expense is the area for storage of the cut parts, and to pack the kits for shipping. So I can rent a smaller shop for this business than I would otherwise have had to do.

    Cha-Ching, saves money from step 1.

    But I have also not had to spend any of my time time (or money on shop personnel) to make the parts. Nobody had to mix the resin, or lay out the infusion manifold, or roll on the peel ply. No wet-knifing the parts, no sandpaper, no peeling off the infusion bleeders and layers of plastic. No motorized grinder trimming or sanding the edges of carbon, spraying toxic itchy carbon dust all over a shop that then needs to be cleaned up by somebody. None of it.

    Cha-Ching...

    Now it comes time to ship the kits out (to the crowd of rioting customers who are making me filthy rich in aviation). The primary majority of the sheet metal would go out as a stack of 5 or 6 layers of thin sheet metal and one layer of plexiglas, sandwiched in cardboard, with wood strips on the sides. And one 4 inch diameter 8 foot long piece of PVC pipe with caps on the ends for the tubes, extrusions and bent angles. The composite fuselage shells would have required a 3 x 3 x 8 foot wooden crate to be built and then shipped.

    Cha-Ching...

    Pardon my smart-ass-ness, but those cost savings alone are pretty significant factors. Importantly, for a small niche market thing like this, being able to do it without any of the one-time startup costs of molds, no staff and payroll, and significantly reducing the pre-revenue outlay of shop space, is a freakin' huge deal to a small entrepreneur guy who would be funding this out of his pocket as a roll of the dice.

    The composite fuselage would look prettier, have a little lower drag, etc. But at what cost? The composite fuselage would create a lot of momentum towards a molded canopy, like the last version of Debreyer's Pelican. Maybe one of you guys can call Aircraft Windshields or Todd's Canopies or whoever, and ask for a price on a Libelle glider canopy (very close approximation to this requirement).

    I'll be right there with the Defibrillator to bring you back :)
     
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  15. May 18, 2017 #15

    FritzW

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    I'm torn between wood/fabric and aluminum. I could see a cleverly CNC'd aluminum wing going together really fast. ...as long as making the ribs didn't defeat the "quick and easy" requirement. I could also see a foam rib with captrips wing going together almost as fast, and the ribs would come off the CNC machine ready for glue. It would sure meet the cheap and easy criteria and still go together pretty quick.

    Side note: I think the 'ol battery on tracks trick could solve the CG issue, just turn the crank until the arrow lines up with the pilot weight.
     
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  16. May 18, 2017 #16

    Victor Bravo

    Victor Bravo

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    A guy who had worked with Jim Marske, a Canadian fellow named Mat Redsell, had developed or flight tested exactly such a device on the Marske Pioneer 2. He had a crank or clothesline mechanism, which ran a battery or lead weight back and forth in the fuselage to trim it for static balance AND flight trim. Apparently it worked exceptionally well, and resulted in measurable performance gains. A well known builder and proponent of the Marske flying wings, USAF General Mike Hostage, was also reported to be testing something like this on the Pioneer 3.

    One of the race modification shops and I did testing years ago on sailplanes (non-flying-wing types) with adjustable balance, using a separate water ballast tank in the vertical fin. It allowed (otherwise unsafe) rearward CG conditions, which delivered very noticeable gains in some flight modes (also delivered some underwear changes in other flight modes...). We could take off at the certified aft CG limit, then dump water out of the forward ballast tanks (wings), and then dump water out of the tail tank to return the CG to the certified range.

    Years before this, there had been testing done on open class sailplanes (about when the Nimbus 3 came out) up in Minden NV where a block of depleted Uranium (really) was mounted on a steel tube in the fuselage and moved back and forth by means of a crank. Dick Brandt is the name I have a distant memory of.
     
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  17. May 18, 2017 #17

    vtul

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    There are a lot of ways to skin a chunk of foam. :gig:

    Skypup manages it.

    The Opal fuselage at least seems to whisper polystyrene, shape me..........
     
  18. May 18, 2017 #18

    vtul

    vtul

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    Of course 150 kts and 2000 mile range is frowned upon in a Part 103 plane.
     
  19. May 18, 2017 #19

    Victor Bravo

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    The Facet Opal does not look cheap or simple to me. It looks like a very high performance airplane, with retractable gear, a wet wing, round composite fuselage, a molded canopy, a fully "buried" engine, and a very tight cockpit not suitable for larger people. It's also twitchy to fly as far as I have read, probably like a full-on racer instead of a sport plane.

    I definitely like the Facet Opal and am every bit as impressed as everyone else seems to be. But I don't see it as a candidate for a cheap or simple airplane, flying wing or otherwise.
     
  20. May 19, 2017 #20

    Hot Wings

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    Is it because of the particulars for that plane? It seems to me that a constant chord flying plank, which is what the Opal is, would be the simplest, lowest parts count and quickest to build of all of the FW variations. I personally think that the AV-36/Pelican planform is more attractive. With a nice looking fuselage like the Opal it would be even more appealing.

    The Opal fuselage could be essentially duplicated with just one compound curve glass nose piece. The canopy could be replaced with a flat wrap plexi piece. You can wrap the plexi in 2 planes with the second starting under the skull cap. The tail cone could be little more than a couple of flat wrap sheets as well. With these methods you would get 90% of the look with only 40% ?? of the work.

    Not trying to be argumentative, just trying to get a feel for the why for the assessments/opinions.
     
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