Non-conformist> Composite Solid Propellants
Первое топливо с битумом (GALCIT-53):
It would consist of potassium perchlorate ... as oxidiser, common asphalt as used on roads as a binder and fuel. These could be cast, after being mixed, into a combustion chamber. A test of the propellant, designated GALCIT 53, was quickly made and the results were so promising that work on other propellant types was dropped for a long time.
Развитие (GALCIT 61):
GALCIT 61-C by Mills give the following composition: 76% potassium perchlorate and 24% fuel. The fuel component was 70% Texaco No. 18 asphalt and 30% Union Oil Company Pure Penn SAE No. 10 lubricating oil. The fuel was liquefied at about 275°F, the pulverised potassium perchlorate added to it, and the mixture thoroughly stirred. The mixture was then poured into the combustion chamber, which had been previously lined with a material similar to the fuel component, and allowed to cool and become hard. This propellant, when burned at a chamber pressure of 2,000 psi., had a chamber temperature of 3,000-3,500°F, a specific impulse of 186, and an exhaust velocity of about 5,900 ft. per sec. Storage temperature limits were from -9 deg F to 120 deg F. GALCIT 61-C was developed in 1943 and used in service JATO units by the Navy until the end of World War II. The propellant is also used on the Private A and F research rockets.
Замена битума тиоколом:
In 1944, Charles Bartley joined Mills' group, and in 1945 introduced as a replacement for asphalt a castable elastomeric material, polysulfide rubber, produced by Thiokol Chemical Corporation. The polysulfide rubber, compared to asphalt, produced a propellant much better both as regards storage temperature limits and hardness at high atmospheric temperatures. The latter property was especially important in the design of high-thrust engines requiring a charge with an internal-burning surface rather than a cigarette-burning surface.
Т.е. тиокол больше подходил для канальных моторов - он держал форму заряда, в отличие от битума, который нормально работал в торцевых зарядах, которые при любых разумных температурах хранения держали сами себя, не требуя каких-то повышенных механических свойств от связки.
Из прочитанного я понял, что автор топлива (Парсонс) заменил ПХК на ПХА исключительно по причине большого количества плотного белого дыма, который образовывался при сжигании топлива на основе ПХК. Дым не устраивал заказчика (военно-морской флот). Во влажном воздухе с ПХА дыма меньше не стало, однако возвращаться к ПХК уже не стали. Почему - не пишут.
Если "cigarette-burning charge" это "заряд торцевого горения", то, как я понял, изначально топливо ПХК-битум использовалось именно в такой конфигурации.
Serge77> ... как страшный сон ...
А вообще затяжной кошмар у них получился - всю войну штамповали ракеты, ускорители, и никак не могли проснуться... Странно.