Will's flying wing

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Will Aldridge

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Got a little ADD going on with my other project and the cheap flying wing thread got me thinking and drawing and here's what I've come up with:
20170522_200651.jpg20170522_200704.jpg

Haven't done any calculations, just TLAR'd it. It's 16.5 ft long, 15 ft wingspan with 90 sq ft wing area all aluminum and the vw engine would be bolted directly to the firewall for simplicties sake. The pilot sits about on the cg and the root chord is 10 ft so I'm hoping that would make it a little less prone to instability due to varying c.g.

Because I have no idea what airfoil to use (thinking maybe the same as the Dyke Delta if anyone knows what that is) I used a NACA 0018 at the root and a 0015 at the tip. I think I need reflex on the tailing edge but don't know how much. Anyway comments and suggestions welcome.
 

Will Aldridge

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Thanks Doug. I'll check out your link.

Just been adding a little structure to see how it would work. The cockpit is 30" wide so nice and roomy, but as you can see the spar cuts off the pilots knees20170522_220817.jpg

Can anyone steer me to a similar design using sheet aluminum where the spars come together at an angle like that and have to have holes in them?
 

cluttonfred

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Just out of curiosity, why the angled spars? With the spars in a straight line tip to tip you'll increase the distance from the elevators to the CL for better authority and damping and move the ailerons closer to the CG so that differential movement won't have as much effect on pitch.
 

Will Aldridge

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Just out of curiosity, why the angled spars? With the spars in a straight line tip to tip you'll increase the distance from the elevators to the CL for better authority and damping and move the ailerons closer to the CG so that differential movement won't have as much effect on pitch.
I guess I didn't make it as clear as I intended in the first post I have no clue what I'm doing when it comes to flying wings. I basically copied the wing platform of the Dyke Delta.

About spar location my brain was locked into the mode of put the spar at the thickest point which with the airfoil I just arbitrarily drew in was about the quarter chord point. I'm assuming part of your question is "why is the planform swept aft a far as it is" which if it was forward swept would allow wing tip ailerons to be closer to the cg.

The answer to that was i drew what i think looks cool. I was vaguely aware that i needed ailerons on the outboard half of the trailing edge and elevators inboard and the forward sweep of the trailing edge would get the ailerons slightly closer to the cg. But perhaps it won't be enough?
 

cluttonfred

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Yup. What I was suggesting as to sweep the trailing edge forward three times as much as you sweep the leading edge back (speaking in percent of chord, not degrees). That would put the spar at the thickest point of the wing tip to tip, but in a straight line. The resulting planform would be very much like a Fauvel AV-60/61 but with lower aspect ratio.

planAV61.gif
 

Riggerrob

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An old-school engineer would tell you to install a ring spar. Ring spars are sort of continuous spars (wing-tip to wing-tip) with a huge bulge (aka. Fuselage bulkhead) in the middle. The bulge/bulkhead has a huge hole in the middle.
Ring spars are fashionable on jet fighters, but too complex for most home builders.

Another option is installing conventional swept spars in the outer wing panels, then hinge/bolt them to the centre-section/wing root/fuselage. Since your wing root/fuselage is so deep, you can route spars and bulkheads in a variety of positions to a comrade various spars, pilots, landing-gear legs, etc.

Have you looked at the "Flying wing for a simple ...." thread? Contributors to that flying wing thread have invented several clever solutions.

Maybe we should ask MODERATORS to blend these two threads???????
 

Jay Kempf

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Thanks Doug. I'll check out your link.

Just been adding a little structure to see how it would work. The cockpit is 30" wide so nice and roomy, but as you can see the spar cuts off the pilots kneesView attachment 62272

Can anyone steer me to a similar design using sheet aluminum where the spars come together at an angle like that and have to have holes in them?
Will,

I have looked at this sort of thing until I ran out of configurations to try. Had a BWB small craft that I worked on for years. The truth is you can have a perimeter cage around your panel and canopy frame that would carry all the loads through the area where you need your feet to go. With some gusseting you can build the spar carry through and leave all but a center post between your knees. Everything else would be below the seat or above/behind the panel. Rutan designs are tighter than what you are talking about. I always thought the whole benefit of these designs was just how wide and cockpit was so you can spread the panel out wide and put things in non traditional places to get that comfy cockpit around the elbows, hips, knees etc... It also gives you the benefit of one simple survival cage that the rest of the structure bolts or is bonded to.
 

harrisonaero

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Will, before you get too enamored I suggest building and flying a simple hotwired foam RC version of this and then of your design and seeing which is more fun to fly. I've designed and flown a lot of different RC types and don't enjoy the flight qualities of flying wings- too twitchy.
 

Victor Bravo

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Will, congratulations on doing a very interesting rendering! I'm jealous of your ability to do stuff like that.

The design as drawn might not have as much visibility as it needs. Even if you solve all the other various issues, ring bulkheads, etc. you may create an aircraft that is not as safe or enjoyable to fly as you wanted. Aesthetics and visibility aside for a moment, putting the pilot on top of the wing instead of inside the wing would solve more than just that one problem. It would give you room for fuel tanks and retractable landing gear, it would allow the spar to be built without amputating the pilot's legs, and it would improve visibility.
 

Will Aldridge

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Will, before you get too enamored I suggest building and flying a simple hotwired foam RC version of this and then of your design and seeing which is more fun to fly. I've designed and flown a lot of different RC types and don't enjoy the flight qualities of flying wings- too twitchy.
As i kind of said i needed a little break from my primary design and this looked like a fun thing to explore. There are a couple sheets of dollar tree foam board in my closet that are slated for this project once it is more defined.

The design as drawn might not have as much visibility as it needs. Even if you solve all the other various issues, ring bulkheads, etc. you may create an aircraft that is not as safe or enjoyable to fly as you wanted. Aesthetics and visibility aside for a moment, putting the pilot on top of the wing instead of inside the wing would solve more than just that one problem. It would give you room for fuel tanks and retractable landing gear, it would allow the spar to be built without amputating the pilot's legs, and it would improve visibility.
If i were to actually build this i would install a camera in the nose so i could see what was in front off me on final and when taxiing. I must be kind of strange in one regard, when flying i spend more time looking at the sky and enjoying that part of the view than i do looking down. Some people like looking at the ground when they fly but me, not so much. As for room for stuff, maybe it's just that I've spent the last ten years trying to stuff a lot of stuff into a tiny package (my other design) but there is massive amounts of space in this thing, the only obstacle is the afore mentioned spar.

As for stability/ enjoyment potential you're all probably right and i may abandon this project before too long, or maybe not.
 

cheapracer

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Will, keep it simple, triangulate the end of each spa to a joining point, with a strengthening cross brace if needed, and there's your leg space.

will.jpg
 

Victor Bravo

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If you accept the concept of putting the pilot's legs above the spar, the amount of room inside the wing and fuselage both increase. You will have more space than you would have had otherwise.

BTW I'm not talking about making it as tall as the AV-61 in Matthew's posting. I'm saying raise the knees above the (full height) spar as little as possible, and leave the pilot's butt as far down as possible, and accept the minimum possible "height" of the cockpit.

I'm not saying you should sit the pilot on top of the wing entirely... the pilot's butt should still be between the ribs as much as possible.

Look at the drawings of an F-1 race car driver seating position.
 

vtul

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Hmm, that post and drawing changed! Magic. New piece added.

Now it shows stressing the center of the web with a link.
 

cheapracer

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Hmm, that post and drawing changed! Magic. New piece added.

Now it shows stressing the center of the web with a link.
Yes, I realised Will's design may not have the cockpit structural support that a more typical aircraft design can offer.
 
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