Walter HWK 109-507
The HWK 109-507 was a
It was produced by
Missile
The Hs293 has been variously described as a missile or as a boosted
As the engine was mounted below the missile fuselage, the exhaust nozzle pointed downwards at 30°, so as to align the line of thrust with the centre of gravity of the missile.
The engine had a burning time of around 10 seconds. After this the missile glided to the target, taking up to 100 seconds for a range of 8.5 km.[3]
As it was intended for attacking lightly- or unarmoured targets, it did not require an armour-piercing high impact speed.[i]
The same engine was also used for the planned Hs 294, Hs 295 and Hs 296 missiles. As these larger missiles weighed twice the Hs 293, they used a pair of the engines, one under each wing root.[4]
Development
This engine was a development of the
The 109-507 was developed from the 109-500. As a missile engine, it was only required to work once, and for a short duration. It was thus simplified in both its features and in its construction materials. Rather than the complex centrifugal
Engine
The engine's fuel chemistry used 80%
Propellants are forced into the combustion chamber by compressed air, stored at 200 bar (2,900 psi) in two steel vessels. This pressure is released through an electrically-fired cartridge that opens a valve with a blow-out disc. This is the full extent of the electrical control system. Once fired, the valve does not close again. A pressure regulator delivers air at 33 bar (480 psi), through a shuttle valve that pressurised first the catalyst tanks and then the propellant tank. This delay ensures reliable ignition in the combustion chamber. A non-return valve ensures that no catalyst can flow backwards into the air or propellant plumbing, with an explosive result. A rubber diaphragm, broken as propellant pressure builds, ensures that there is no backflow through the combustion chamber either.[5] Z-stoff was known for problems of clogging injectors and so an inline filter was used.[iii]
The propellant injector in the combustion chamber is a simple
Thrust varied through the boost phase, as air pressure and propellant flow fell, dropping from 600 kgf to 400 kgf.[6]
The engine pod had a
References
- Fritz-X was intended to attack armoured capital shipsand so was unpowered, free-falling steeply and reaching a high speed, at the cost of a range half that of the Hs 293
- ^ The more complex 'hot cycle' then burned a kerosene fuel in combination with the evolved oxygen. These were more powerful and fuel efficient, but also more complex and required turbopumps with precision moving parts.
- ^ The unreliability of Z-stoff and its clogging meant that it was largely replaced with other fuel cycles for manned aircraft.
- ISBN 085368-053-1.
- ^ "Hs 293". Walter Werke.
- ^ Department of the Army (March 1953). "German Explosive Ordnance" (PDF). Technical Manual. pp. 200–203. TM 9-1985-2.
- ^ Hogg (1970), pp. 25–26.
- ^ a b c d "The HWK 109-507 Motor". Walter Werke.
- ^ "Rocket Engine, Walter HWK 109-507". Smithsonian.