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Exploring delta's and my results.

L Edge

Well-known member
#1
At the flying field one day many years ago, a member gave me a F-117 that was a mess. He couldn't get it to fly so I ended up with it. It was a beast and very unstable and it lasted about a dozen flights before the ground god's got it. So I decided to explore deltas, but I wanted something that is easy to fly and can handle winds.

Being old school, played with sheets of paper and decided to have a cambered surface on the top and flat on the bottom like a trainer. Did some research in NASA, so I ended up sketching an airfoil(to explore blended wing body and see what happens.) Most of my other designs were in the 30ish numbers, so I ended up with he finished product of

Length 34 inches
Width 32 inches
Motor E-flight Park 370
Prop APC 7 x 5
CG is 21" from nose

Knew I needed vertical end plates for stability and wanted desperately prop protection. So end up 4.5 at base, 2 inches at top and 5 inches vertically.

For prop protection, shaped 2 inner vertical plates on paper so it was 2 3/4 inch below plan and blended in shape.
Cut out area for motor/prop and allowed 6 1/4 " gap which gave the elevons a dimension of 2 1/2" wide by 11 1/2' length. Made gap wide enough for an 8" prop just in case it would fly better/worse han the 7.
Now for the angle of the delta. After many trials by error, ended up with a 2 17.5 degree angle for a total angle of 35 degrees.

Need to exit now. Will continue--
 
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L Edge

Well-known member
#2
Here is a overall picture showing what it looks like. The flat bottom piece joins the top segment togeather at the control surfaces.


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Bent down and sanded the leading edge of the outer wing. Had to install servos before I glued the top down.

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Rear view showing control surfaces and outside fins. Shaped the motor mount and located motor above so it is protected from ground.

IMG_0370.JPG


Notice how inner vertical fins help control yawing, but is allows protection of motor or prop damage.

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Here is what the inner vertical stab looks like.

This was the initial design.
Bottom view

IMG_0373.JPG


The bottom inner vertical is 10 1/2" long and is where the outer wing starts.

One thing I found is that yaw control could be improved greatly if there is an actual moving rudder especially when it is in high alpha or approaching hover. Past models spin around and to control it from doing this, conceived the "udder rudder" which is putting a movable rudder(in front or rear) on a servo that has a long servo arm.

Since the airflow is a lot slower and you want max control, I used negative exponential(DX-9) where a small movement of TX rudder allows large movement of the rudder. That combo works rather well. Search UDDER RUDDER for how to do it.

Top View

IMG_0374.JPG


Side View

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Plane is 5+ years old (glue is aging like me) and when I go to the field, I let the better fliers try it. As you can see, had some mishaps, but that is the fun to let some of the guys in on the fun.

If anybody would like to build this after viewing video, go ahead. Lost paperwork that I sketched and will actually measure to help you if I can.

I never made a video, so I will do it when I can. This is a very unique plane and flies totally different.
 
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danskis

Well-known member
#4
Cool plane....this could be on the build list!! It would be great to have a sketch of the construction and the airfoil.