Facet Opel

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Hephaestus

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Does this help?
If thrust line is axis system wing is at 3° and reflex is 6°. Whole thing propped up at 8° in takeoff trim. Tiny fixed wheel gives clearance so the nose gear doors can sequence (butterfly open) first and the geometry of the nose retraction makes the tire contact first. Tricky, huh? I've been obsessing over this a bit for a bit. Happens. Might be the easiest airplane of this type to get in and out of ever. Main gear trailing link would attach to a bracket on the rear spar. There would be some sort of rib there to take all the torsion and to mount the shock to.
View attachment 96935
See how the nose wheel caster centers and the tire touches the pavement first during extension... Plenty of clearance to get the doors out of the way first. Would need a simple arduino/Pi sequencer and some relays, servos for the doors, 12/24v linear actuator for the extension/retraction.
View attachment 96937
Out of curiosity, what engine? Using a prop extension?
 

Jay Kempf

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Precisely the reason I found the idea worth stealing!

You might consider a 2 position nose gear? One for take off and a second for landing. Skip to 3:20

Dunno, lots of choices. Anything north of 75 HP would be more than adequate. 120HP turbo would make it a rocket. Prop extension certainly. Aeromomentum? I like twin side by side quad motors from Polaris. Already dry sump, light, lots of grunt down low. Turbo kits available. Rotax B box would work. I'm a fan of inline water cooled.

Don't think a two position nose gear at this AR. I think it will be able to use the same AOA for both, say 2-3° short of stall with elevons still flying properly. Should be fine. Just settle onto the mains in a big mush in ground effect. Short AR needs some more AOA (3D wing) at flare than a high AR wing.
 

rotax618

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Given the distance between the aerodynamic centroid and the elevon hinges would be around 800mm, please explain how a bit of washout and a specially selected airfoil can somehow give acceptable pitch stability. What’s going to prevent over control tumble?
 

Jay Kempf

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Don't think washout would cure pitch sensitivity but it would help the wing from all stalling at once and keep the outboard parts of the wing flying at slow speeds. It would also help to distribute lift better being rectangular. It would need a better camber line and more thickness up front to keep it from twitching in pitch. Pitch instability on these things comes from control blanking my guess. Airfoil choice, maybe some separation where it wasn't doing any good... Things like that. That landing gear was really tightly spaced and from what I saw the takeoff roll did a lot of bobbing and weaving. That and over sensitive stick gearing might be enough to cause major PIO. PIO can be overcome with skill and time. Each platform is different. The BD5 suffered from major PIO until they dialed it in.
 
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sigrana

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Yes indeed, I'm guessing the Facet Opal probably had the landing gear in the fuselage because he wanted a wet wing or enormous fuel tanks for his distance record flying.

But a realistic sport Opal would not need ALL of that fuel, maybe 2/3 or 1/2 of that Winton wanted. So this would allow the gear to fold up into the wing would reduce the complexity and improve the ground handling.
The aircraft was called a Facet OPAL, not opel. I was a close aquaintance of the late Scott Winton.
 

rotax618

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You are correct sigrana, I simply copied the incorrect name of the thread rather than start an argument about the spelling, I met Scott on several occasions and was a friend of his father Col.
 

Victor Bravo

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The aircraft was called a Facet OPAL, not opel. I was a close aquaintance of the late Scott Winton.
Agreed, I think you will find most of my references to this aircraft use the correct spelling, naming the aircraft after the precious gemstone as opposed to the future automobile manufacturer (and 1929 rocket glider designer).
 

nestofdragons

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The Opal has very narrow landing gear. But if you want to keep something light and have little drag, you need to accept alternative landing gears, i guess. One might see a solution in just two central wheels and wingtipwheels like they had on the Pelican flying wing. Or maybe even consider the landing gear of the Verhees Delta.

I like this kind of minimum design. :)

Kind regards,
Koen Van de Kerckhove
pelic3-v.jpg
verhees.jpg
 

Hot Wings

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Agreed... I have been doing a lot of thinking about a derivative of the Pelican.
What kind of mission parameters?
I personally think there is a much larger potential market for a Pelican/Opal hybrid than my AV-36/361 and it would fill many of the check boxes attempting to be filled with the VP-21 and flying motorcycle threads.

Flying wings like the Mitchell U-2, B-10 and the AV have their place but a lower aspect ratio version can make them more desirable for some missions.
 

Victor Bravo

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What kind of mission parameters?
One modest level above the original parameters for the Pelican. Not trying to fly on 9-12HP, not trying to make an airplane that weighs 75KG. Part 103 would be nice, but is not a first-level requirement. Cost, simplicity, and able to have the parts made on a CNC machine are higher priorities. If someone won't make the commitment to get a Sport Pilot license and Basic Med, I may not want to take that risk of selling them a kit.

My version would be sheet metal and pop rivets, with either the Briggs 30HP conversion or a Polini Thor. Not quite minimalist, it would still have an enclosed cabin land be the size of the Pelican. I'm wrestling with the different methods of fitting it into a trailer, or a shipping container, or a minimalist "portable garage" fabric covered structure.
 
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Hot Wings

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I'm wrestling with the different methods of fitting it into a trailer, or a shipping container
I think that is going to be one of the bigger challenges with the Pelican.
The center section is just shy of 10 feet so folding the wings at the transition is still over width.
The chord is 6.5 feet so the entire forward fuselage would have to be removable.
Reducing the wing area probably isn't an option so making the center section smaller and folding the wings, or the chord narrower to allow a simple removable nose forces us to a longer span.
Having the entire fuselage removable - like the AV-45 - might be the best way. This means auto-connect controls but if CNC is part of the plan then the parts aren't difficult.

When you say aluminum I'm visualizing something more like the prototype Pelican fuselage shape with a "D" leading edge and fabric covering similar to a Lazair or the other Pelican?

Edit: Adding Word version of a Pelican PDF converted to English via Google - unformated or edited in any way.
 

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Victor Bravo

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Yes, I'm looking into the forward fuselage coming off and sliding the airplane into a trailer sideways. Versus removing the wings at the dihedral break, with the dihedral break moved inboard to an 8 foot dimension.

You are correct in the concept of a boxy sheet metal fuselage and a D-tube wing. Rear section of ribs built as light aluminum tube and gusset truss.
 

erkki67

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FE889F01-77F8-4A5E-895F-208AE7D66894.jpeg
for me it would be desirable to have this fuselage of the red lower bird, why not a Polini Thor 250 or similar powerplant, and a sturdy suspended central wheel. The center section should not be wider then 2500mm or less to remain street legal here in Europe. No composites.sheet metals why not, even if I would prefer wood. An a overall design similar to the Pelican, with a bit less wingspan, due to the power increase from 15 to 35hp.
 
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