Messerschmitt Me 163
The Messerschmitt Me 163 Komet, designed by Alexander Lippisch, was a German rocket-powered fighter aircraft. It is the only rocket-powered fighter aircraft ever to have been operational. Its design was revolutionary, and the Me 163 was capable of performance unrivaled at the time. German test pilot Heini Dittmar in early July 1944 reached 1,130 km/h (700 mph), not broken in terms of absolute speed until November 1947. Over 300 aircraft were built; however, the Komet proved ineffective as a fighter, having been responsible for the destruction of only about nine Allied aircraft.
The fuel system was particularly troublesome, as leaks incurred during hard landings easily caused fires and explosions. Metal fuel lines and fittings, which failed in unpredictable ways, were used as this was the best technology available. Both fuel and oxidizer were toxic and required extreme care when loading in the aircraft, yet there were occasions when Komets exploded on the tarmac from the propellants' hypergolic nature. Both propellants were clear fluids, with different tanker trucks used for delivering each propellant to a particular Komet aircraft, one at a time, with one truck - usually the one delivering the C-Stoff hydrazine/methanol-base fuel - leaving the immediate area of the aircraft following its delivery and capping off of the Komet's fuel tanks from a rear located dorsal fuselage filling point just ahead of the Komet's vertical stabilizer, before the other truck - most often an Opel Blitz tanker truck, of a special Ausführung S model carrying the very reactive T-Stoff hydrogen peroxide oxidizer would come anywhere near to deliver its oxidizer load to the fighter for safety reasons, through a different filling point on the Komet's dorsal fuselage surface, located not far behind the rear edge of the canopy. The corrosive nature of the liquids, especially for the T-Stoff oxidizer, required special protective gear for the pilots. To help prevent explosions, the Walter rocket engine and the Komet's propellant storage and delivery systems were frequently and thoroughly hosed down and flushed with water run through both the fuel and oxidizer tanks and rocket engine's propellant systems before and after flights, to clean out any remnants of the hypergolic fuel and oxidizer. The relative "closeness" to the pilot of some 120 litres (31.7 US gal) of the chemically active T-Stoff oxidizer, split between two auxiliary oxidizer tanks of equal volume to either side within the lower flanks of the cockpit area — besides the main oxidizer tank of some 1,040 litre (275 US gal) volume just behind the cockpit's rear wall, could present a serious or even fatal hazard to a pilot in a fuel-caused mishap with the Me 163B.
Two prototypes were followed by 30 Me 163 B-0 pre-production aircraft armed with two 20 mm MG 151/20 cannon and some 400 Me 163 B-1 production aircraft armed with two 30 mm (1.18 inch) MK 108 cannons, but which were otherwise similar to the B-0. Occasional references to B-1a or Ba-1 subtypes are found in the literature on the aircraft, but the meanings of these designations are somewhat unclear. Early in the war, when German aircraft firms created versions of their aircraft for export purposes, the a was added to export (ausland) variants (B-1a) or to foreign-built variants (Ba-1) but for the Me 163, there were neither export nor a foreign-built version. Later in the war, the "a" and successive letters were used for aircraft using different engine types: as Me 262 A-1a with Jumo engines, Me 262 A-1b with BMW engines. As the Me 163 was planned with an alternative BMW P3330A rocket engine, it is quite safe to assume the "a" was used for this purpose on early examples. Only one Me 163, the V10, was tested with the BMW engine, so this designation suffix was soon dropped. The Me 163 B-1a did not have any wingtip "washout" built into it, and as a result, it had a much higher critical Mach number than the Me 163 B-1.
The Me 163B had very docile landing characteristics, mostly due to its integrated leading edge slots, located directly forward of the elevon control surfaces, and just behind and at the same angle as the wing's leading edge. It would neither stall nor spin. One could fly the Komet with the stick full back, and have it in a turn and then use the rudder to take it out of the turn, and not fear it snapping into a spin. It would also slip well. Because it was derived from a glider, it had excellent gliding qualities, and had tendency to continue flying above the ground due to ground effect. On the other hand, making a too close turn from base onto final, the sink rate would increase, and one could quickly lose altitude and come in short. Another main difference from a propeller-driven aircraft is that there was no slipstream over the rudder. On takeoff, one had to attain the speed at which the aerodynamic controls become effective—about 129 km/h (80 mph)—and that was always a critical factor. Pilots used to flying propeller-driven aircraft had to be careful the control stick was not somewhere in the corner when the control surfaces began working. These, like many other specific Me 163 problems, would be resolved by specific training.
The performance of the Me 163 far exceeded that of contemporary piston engine fighters. At a speed of over 320 km/h (200 mph) the aircraft would take off, in a "sharp start" from the ground, from its two-wheeled dolly. The aircraft would be kept at low altitude until the best climbing speed of around 676 km/h (420 mph) was reached, at which point it would jettison the dolly, pull up into a 70° angle of climb, and rapidly climb to a bomber's altitude. It could go higher if required, reaching 12,000 m (39,000 ft) in an unheard of three minutes. Once there, it would level off and quickly accelerate to speeds around 880 km/h (550 mph) or faster, which no Allied fighter could match. The usable Mach number was similar to that of the Me 262, but because of the high thrust-to-drag ratio, it was much easier for the pilot to lose track of the onset of severe compressibility and loss of control. A Mach warning system was installed as a result. The aircraft was remarkably agile and docile to fly at high speed. According to Rudolf Opitz, chief test pilot of the Me 163, it could "fly circles around any other fighter of its time".