Low CG

a tale of no tail

The moment created by the wing gets (fully or partially) compensated by the very low CG. This technique is often used with ultra light. Mostly hang gliders (using weight shift as flight control) use this technique to its full use. "Mitchell used this technique for his B-10 flying wing ultra light." This quote from an Air Enthusiast edition probably mentioned that if the cockpit would be higher placed, that the control surfaces needed to be larger to control the airplane. The newer U-2 of Mitchell has a higher placed cockpit, but it also has a longer force arm between the CG and the control areas (the B-10 has a straight wing, while the U-2 has some back sweep). Both airplanes use the low CG technique partially. Flight control is done by control areas hung under the trailing edge of the wing.

Advantages:

  • Very easy in design. No fuss with twists and sweep.
  • You still can use airfoil with some pitching moment Cm like a "normal" airplane (not a flying wing). This way lift is larger than the auto stable airfoils used in unswept designs.

Disadvantages:

  • You have not the opportunity to place pilot or engine or equipment in the wing. You cannot make profit from the available space in the wing.
  • A cockpit hanging under the wing makes more drag then an integrated cockpit in the wing. Probably the reason why Mitchell made his second design, the U-2, has an integrated cockpit.