A flying wing pusher airplane design

[David Lewis]

Hello all, This is a two-place airplane I've designed. It will use a 3-axis artificial stabilization system. The wing airfoil is not reflexed. The horizontal stabilizer provides the down force to counteract section pitching moment. I welcome your comments.

[Bill Berson]

I would be concerned about the horizontal tail down load creating wing tip positive twist couple. Could cause tip stall or worse.

[David Lewis]

Thank you for pointing that out, Bill.

The wing would need to be stiff in torsion.

[Birdmann]

hey Dave,
Flying wings are trickey, Historically there have been several of them but they didnt do too well in the market.Before spending alot of money on this make sure you study past models. Personaly i like them but i dont want to own one,
Jeff

[Bill Berson]

Takeoff can be tricky. Read the Sport Aviation archives for "Dean Delta". A fatal crash on first takeoff. The thrust on takeoff pushed the nose down. It wouldn't rotate with no prop blast over the tail. But when the pilot aborted at high speed, the lack of nose down thrust then caused a pitch up and it went out of control.

[David Lewis]

I appreciate your excellent input, Bill and Birdman! All important points. Two features that make an airplane suitable for low time pilots is plenty of stability, and low stalling speed. Two problems with flying wings is lack of stability, and the reflexed airfoil which reduces lift coefficient. I've been impressed, however, with the model radio control flying wings I've seen, which are steady and easy to fly. They use a gyroscopic stabilization system adapted from quadcopters (drones).

[tmnolte]

Takeoff can be tricky. Read the Sport Aviation archives for "Dean Delta". A fatal crash on first takeoff. The thrust on takeoff pushed the nose down. It wouldn't rotate with no prop blast over the tail. But when the pilot aborted at high speed, the lack of nose down thrust then caused a pitch up and it went out of control.

Bill - I found one of the articles from 1963 but couldn't find anything else. Not to divert the thread but it is interesting given the level of effort put into designing and building the plane that he would have has such a misunderstanding of it's handling characteristics, doesn't it?

[Birdmann]

Dave i can feel for your interest for these tings, i do too, so many RC planes are flying wings.
In the subject of safety and usability, why not use a canard like the Velocity or Berkuit, they are essentially flying wings with an elevator stablizer in the front.
These are already developed and are very safe and useable. If you want to get more bang for your buck this is the way to go, It sometimes takes many years to develope
a new model like this, you are risking your money and your life.
jeff

[David Lewis]

Thanks Jeff, Ron and Bill for valuable advice and suggestions. I never understood the advantage of canards over ordinary (tail-in-the-back) configurations. Can you enlighten me?

[Frank Giger]

Very cool that you're thinking outside of the box - at the minimum you will learn what won't work, which is just as valuable as knowing what will.

A question:

The horizontal stabilizer provides the down force to counteract section pitching moment.

I'm not exactly sure what you're driving at here, but you may have just answered your own question in regards to canards (other than canards up front are out of the way of prop blast streams of air and reduce drag, along with other things more educated folks will share).

You could, if you wanted to make things simpler in one way and more complex in another, ditch it entirely. Have the ailerons do double duty, as it were.

I think your sweep on the wings may be a tad aggressive. The overall shape of the design does not imply great speed.