Tailless aircraft
Theoretical advantages of the tailless configuration include low parasitic drag as on the Horten H.IV soaring glider and good stealth characteristics as on the Northrop B-2 Spirit bomber.
This reduces the overall efficiency of the wing, but for many designs – especially for high speeds – this is outweighed by the reductions in drag, weight and cost over a conventional stabiliser.
With reflex camber the flatter side of the wing is on top, and the strongly curved side is on the bottom, so the front section presents a high angle of attack while the back section is more horizontal and contributes no lift, so acting like a tailplane or the washed-out tips of a swept wing.
Reflex camber can be simulated by fitting large elevators to a conventional airfoil and trimming them noticeably upwards; the center of gravity must also be moved forward of the usual position.
Due to the Bernoulli effect, reflex camber tends to create a small downthrust, so the angle of attack of the wing is increased to compensate.
But the drag inherent in a high angle of attack is generally regarded as making the design inefficient, and only a few production types, such as the Fauvel and Marske Aircraft series of sailplanes, have used it.
Some modern hi-tech combat aircraft are aerodynamically unstable in pitch and rely on fly-by-wire computer control to provide stability.
The solution usually adopted is to provide large elevator and/or elevon surfaces on the wing trailing edge.
Unless the wing is highly swept, these must generate large control forces, as their distance from the aerodynamic center is small and the moments less.
In a highly swept delta wing the distance between trailing edge and aerodynamic centre is larger so enlarged surfaces are not required.
However even in the Mirage, pitch control at the high angles of attack experienced during takeoff and landing could be problematic and some later derivatives featured additional canard surfaces.
This reverses the adverse yaw action of the ailerons, helping the plane into the turn and eliminating the need for a vertical rudder or differential-drag spoilers.
[5] Between 1905 and 1913, the British Army Officer and aeronaut J. W. Dunne developed a series of tailless aircraft intended to be inherently stable and unstallable.
Dunne had an advanced qualitative appreciation of the aerodynamic principles involved, even understanding how negative lift at the wing tips, combined with steep downward-angled anhedral, enhanced directional stability.
[6] Although originally conceived as a monoplane, Dunne's initial designs for the Army were required to be biplanes, typically featuring a fuselage nacelle between the planes with rear-mounted pusher propeller and fixed endplate fins between each pair of wing tips.
After his Army work had ended, in 1910 the D.5 biplane was witnessed in stable flight by Orville Wright and Griffith Brewer, who submitted an official report to the Royal Aeronautical Society to that effect.
Dunne gave some help initially and Hill went on to produce the Pterodactyl series of tailless aircraft from the 1920s onwards.
During the Second World War, Lippisch worked for the German designer Willy Messerschmitt on the first tailless aircraft to go into production, the Me 163 Komet.
One of these was possibly one of the first aircraft ever to break the sound barrier – it did so during a shallow dive, and the sonic boom was heard by several witnesses.
Similar to the DH.108, the twin-jet powered 1948-vintage Northrop X-4 was one of the series of postwar X-planes experimental aircraft developed in the United States after World War II to fly in research programs exploring the challenges of high-speed transonic flight and beyond.
