What happens without a tail?
If you have a wooden model of a plane, I would not advise to rip off the tail. If you throw the model without tail, it will dive to the ground. Why? Every airfoil has three forces. Lift, weight (both vertical) and drag (horizontal). If lift and weight are placed on the same spot, the airfoil is stable. But most airfoils are not stable. The lift force is mostly located after the weight force. So it generates a turning moment. This turning moment is compensated with the down pushing force of the horizontal tail surfaces.
A canard has an upward force in the horizontal "tail"-surfaces.
Flying wings, why?
Every plane (with a tail) also has a long fuselage to fix the tail to. This fuselage and tail create extra drag. Performance gets less due to this drag. Many designers came to the thought: "why not delete the fuselage and the tail". Flying wings were born.
The name flying wing is not totally correct. Most full-scale designs still have some sort of fuselage. The Horten-brothers and Northrop made (to my idea) the only pure flying wings. The Horten IX V2 (1945) and the B-2 (1990's) have proven that the concept can be achieved. Other designs have fuselages and fall under the name "tailless airplanes". But some still have vertical tail surfaces. So… we make it ourselves simple and call them all "flying wings".
How flying without tail?
There are four ways when using a rigid wing (not a pure textile wing like a parasail).
- SWEPT WINGS. Give the wing an arrow form (sweep) and twist the wing. If you sweep the wing backwards you need to twist the wing softly downwards.
- Use an AUTO STABLE AIRFOIL (lift- and weight forces on the same point). Here you don't have to use sweep. That is why they are called unswept designs. Sometimes designers do use forward sweep. I will explain this later.
- TAILS ON TIPS. Place horizontal surfaces on the tips of the wing. This is not a pure "tailless design". Although it looks a bit like it.
- LOW CG. Place the center of gravity very low.
FLYING WING DESIGNER!!!!
Marko Stamenovic made a great tool to make your own Flying Wing RC model. You need to be more into wingdesign to understand it, but ...you don't need to be a engineer to use it.
You can find the tool HERE.