High-test peroxide (HTP) is a highly concentrated (85 to 98%) solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with no remaining liquid water. It was used as a propellant of HTP rockets and torpedoes, and has been used for high-performance vernier engines.
Properties
Hydrogen peroxide works best as a propellant in extremely high concentrations (roughly over 70%). Although any concentration of peroxide will generate some hot gas (oxygen plus some steam), at concentrations above approximately 67%, the heat of decomposing hydrogen peroxide becomes large enough to completely vaporize all the liquid at standard pressure. This represents a safety and utilization turning point, since decomposition of any concentration above this amount is capable of transforming the liquid entirely to heated gas (the higher the concentration, the hotter the resulting gas). This very hot steam/oxygen mixture can then be used to generate maximal thrust, power, or work, but it also makes explosive decomposition of the material far more hazardous.
Normal propellant-grade concentrations, therefore, vary from 70 to 98%, with common grades of 70, 85, 90, and 98%.
The volume change of peroxide due to freezing varies with percentage. Lower concentrations of peroxide (45% or less) will expand when frozen, while higher concentrations (65% or greater) will contract.
Hydrogen peroxide becomes more stable with higher peroxide content. For example, 98% hydrogen peroxide is more stable than 70% hydrogen peroxide. Water acts as a contaminant, and the higher the water concentration the less stable the peroxide is. The storability of peroxide is dependent on the surface-to-volume ratio of the materials the fluid is in contact with. To increase storability, the ratio should be minimized.
Applications
When used with a suitable catalyst, HTP can be used as a monopropellant, or with a separate fuel as a bipropellant.
HTP has been used safely and successfully in many applications, beginning with German usage during World War II, and continues to the present day. During World War II, high-test peroxide was used as an oxidizer in some German bipropellant rocket designs, such as the Walter HWK 509A rocket engine that powered the Messerschmitt Me 163 point defense interceptor fighter late in World War II, comprising 80% of the standardized mixture T-Stoff, and also in the German Type XVII submarine.
Some significant United States programs include the reaction control thrusters on the X-15 program, and the Bell Rocket Belt. The NASA Lunar Lander Research Vehicle used it for rocket thrust to simulate a lunar lander.
The Royal Navy experimented with HTP as the oxidiser in the experimental high-speed target/training submarines and between 1958 and 1969.
The first Russian HTP torpedo was known by the strictly functional name of 53-57, the 53 referring to the diameter in centimeters of the torpedo tube, the 57 to the year it was introduced. Driven by the Cold War competition, they ordered the development of a larger HTP torpedo, to be fired from the 65-centimeter (26-inch) tubes. HTP in one of these Type 65 torpedoes on August 12, 2000 exploded on board and sank the K-141 Kursk submarine.
British experiments with HTP as a torpedo fuel were discontinued after a peroxide fire resulted in the loss of the submarine in 1956.
British experimentation with HTP continued in rocketry research, ending with the Black Arrow launch vehicles in 1971. Black Arrow rockets successfully launched the Prospero X-3 satellite from Woomera, South Australia using HTP and kerosene fuel.
The British Blue Steel missile, attached to Vulcan and Victor bombers, in the 1960s, was produced by AVRO. It used 85% concentration of HTP. To light the twin chamber Stentor rocket, HTP passed through a catalyst screen. Kerosene was then injected into the two chambers to produce 20,000 pounds and 5,000 pounds of thrust each. The larger chamber was for climbing and accelerating, while the small chamber was to maintain cruise speed. The missile had a range of 100 nautical miles when launched at high altitude and about 50 nautical miles launched at low level (500 to 1000 feet). Its speed was about Mach 2.0. After a high altitude launch it would climb to 70,000 to 80,000 feet. From a low level launch, it would climb to only 40,000 feet but its speed would still be around Mach 2.0
With concentration of 82%, it is still in use on the Russian Soyuz rocket to drive the turbopumps on the boosters and on the orbital vehicle.