not really, the ramjets would not take effect to give it full thrust until higher speeds. Plus the fact that it couldn't launch with enough fuel, becuase they would leak like a sive until external pressures would tighten up the seals at high speed.
Correct, the SR-71 would taxi and takeoff with 1/4 tanks, and refuel in air because the aircraft was not capable of escaping earth's gravity on takeoff with full tanks.
The SR-71 used JP-7, a triple distilled kerosene with additives. It was used because of it's high flashpoint and thermal stability. JP-7 is a mixture composed primarily of hydrocarbons, including alkanes, cycloalkanes, alkylbenzenes, indanes/tetralins, and naphthalenes, with addition of fluorocarbons to increase its lubricant properties, an oxidizing agent to make it burn better, and a caesium containing compound known as A-50, which aided in
disguising the radar signature of the exhaust plume.~Brian