Delta wing attach looking for ideas

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Wild Bill

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Dec 11, 2013
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Vidalia, GA
Guys I've been sketching out various things and what seems to always meet my needs is a flying wing/delta design.
This would be a small light single seat 40-80hp plane that could meet LSA.

One of the design challenges is what to do about attaching the wing panels. I've looked at a bunch of different ways to build the wing. Probably the best method is foam/composite skins over just a few ribs with a composite spar front and rear. Building the skins alone is a lot of work however and would obviously require the construction of 4 relatively large molds unless I went fully symmetrical.
Even the most basic method would be somewhat costly, and take up a lot of real estate.
Full core foam/glass is too heavy.
So I've considered a fiberglass or built up wood spar with foam or built up ribs and ply skins.
An obvious issue is what to do about the attachment points. The main spar will meet up with the fuselage at quite an angle. This will be aggravated further by my desire to have a slight amount of anhedral in the wings.

One idea is to build the spar where it's perpendicular to the root rib. This means having the spar enter aft of the thickest root portion. And obviously the spar would be much harder to build due to the complex shape required going through at this angle.

So, now what I'm looking at is using (2) 8'X4" OD aluminum tubes. The root rib and the rib on the outboard end of the tube would transfer structural loads to stressed skins. Again not a perfect solution but I think it might have merit. Given the amount of taper in a wing panel like this load distribution is very favorable.

As I mentioned above the plan is to have a fuselage. I've considered not having one but not sure I'd go that route.
See attached picture for a rough idea of the planform. Root chord is 8' (2.43M) panel span is 7' (2.13M)
Thickest point on root section will be in the 10" range
 
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Wild Bill

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Vidalia, GA
Configuration will be similar to that. Obviously lower aspect ratio wings.
Landing gear I have in mind will be tandem mono wheel with "outrigger" gears to keep it level. But that's not set in stone by any means
This is sort of inspired by the Verhees, and stingray delta.
My empty weight goal is a bit lower at 300-350lbs. And for light pilots (Im 150lbs)
 

deskpilot

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JamesG

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Your spar(s) should carry thru the fuselage as uninterupted as possible. Even if they have to have bends and twists, the reinforcement is localized there and worth having it at the point of highest load. The whole problem with the delta form is that its not really a convenient shape. It has a large surface footprint where as the traditional cruxifom airplane shape is easier to work with and fabricate (thus why they are much more popular).

Given your airfoil specs, it wouldn't be that hard to have your "fuselage" be not much more than a canopy and vertical stab. IF you are willing to accept the well known drawbacks a true delta brings.
 

Wild Bill

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Dec 11, 2013
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Vidalia, GA
Thanks guys

Yes, for a relatively small airplane it does cover some area. Not easy to construct compared to a normal wing where you could literally reach all the way across the chord while on a work table.
One of the biggest drawbacks that I see is lack of visibility (takeoff and landing) with a tractor engine configuration. On top of that I would like to sit as far down in it as possible to avoid the tall guppy cockpit. One idea there, is to use a camera system for reference. It's not the same as actually seeing what's in front of you but it can help.
 

autoreply

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Multiple spars and thin composite panels glued onto them might make more sense than ribs?

Alternatively a warren-truss shear web arrangement. Structurally optimal. Could be made by arranging foam in the right shape and glassing over?
 

ThadBeier

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Dec 28, 2010
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Los Angeles, California
Thanks guys

Yes, for a relatively small airplane it does cover some area. Not easy to construct compared to a normal wing where you could literally reach all the way across the chord while on a work table.
One of the biggest drawbacks that I see is lack of visibility (takeoff and landing) with a tractor engine configuration. On top of that I would like to sit as far down in it as possible to avoid the tall guppy cockpit. One idea there, is to use a camera system for reference. It's not the same as actually seeing what's in front of you but it can help.
A forward-swept delta would allow you to sit further forward :)
 

don january

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I alway's thought the wing was the fuselage on a delta wing, What are you going to attach the wing too? what was this a trick question?:) delta wing.jpg you know me alway's looking for the humor in thing's
 

JamesG

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True. the "fuselage" on a blended body or delta wing is just the area of the aircraft where the two wings/airfoils come together. It can have a decernable fuselage like a Mirage III all the way to a B2 where its pretty much just perturbations like canopies and engines.
 

Riggerrob

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How about installing clear floor panels near your rudder pedals .... similar to helicopters.

Structurally, with that deep a wing .... I would go for stressed skins and deep spar webs. My first iteration would also start with foam blocks cut with a hot-wire. I would cut lightening holes, etc. Then I would lay a fibreglass spar web on the exposed face of a foam block and cured it. Secondly, I would pin (toothpicks) the second foam block to the first block then lay the spar cap and outer skin over that. I would try to use the (later discarded) outer foam blocks as jigs during the first couple of adding steps (e.g. use the bottom foam as a cradle while classing the top skin.

Considering how deep the wing root is, you don't really need a fuselage. Like the Verhees Delta you can conceal most of the pilot within the wing root and only add a clear canopy for him to watch the scenery pass by. Just continue the wing spars straight across and use the root ribs to carry fore and aft loads. For example, just bolt, glue, rivet, etc the firewall to the front end of the wing root ribs.

As for how far aft the pilot sits .... start by calculating weight and balance and wait until the second or third iteration before you worry about canopy shape. Verhees Delta's canopy may not be the most graceful curved ... but it is light-weight, easy to build and low drag.

Personally, I am waiting for the two-seater version of the Verhees Delta.
 

dirk_D

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Sep 22, 2010
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Victoria, Australia.
Hi bill, i got the same ideas for a small craft, a side by side 2 seat, twin duct pusher of a mid mount subaru ej (a risky plane).

My ideas for safety involve the roof detaching and parachuting (ditching).

Kinda like a sliding of a motorcycle rather than fighting for control...
 
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