Here is a question - what is the benefit of using scram jets on the Delta Glider DG-S.
Scramjet optimum fuel efficiency is achieved at an altitude of approximately 25,000 metres and a speed of Mach 5.
Burning fuel at the optimum altitude and speed scramjets could travel 2,800 km using 1,600kg fuel (Mach 5 at 25km altitude).
However, main thrusters could use the same 1,600kg of fuel to simply to climb to 50km altitude and then benefit from the lower drag.
The scramjets are 2.5 times more efficient than the main engines only when in their peak operating range. However this range is in a draggy environment.
Scramjets can maintain this speed burning fuel at a rate of 1 kg for every 1,750m.
While this is highly efficient it is not comparable to the efficiency of the Delta Glider at an altitude of 50,000 metres or higher.
Using main engines it takes 1,600kg engine fuel to climb to an altitude of 50 km where drag and fuel usage are negligible.
So what is the purpose of scramjets?
Scramjet optimum fuel efficiency is achieved at an altitude of approximately 25,000 metres and a speed of Mach 5.
Burning fuel at the optimum altitude and speed scramjets could travel 2,800 km using 1,600kg fuel (Mach 5 at 25km altitude).
However, main thrusters could use the same 1,600kg of fuel to simply to climb to 50km altitude and then benefit from the lower drag.
The scramjets are 2.5 times more efficient than the main engines only when in their peak operating range. However this range is in a draggy environment.
Scramjets can maintain this speed burning fuel at a rate of 1 kg for every 1,750m.
While this is highly efficient it is not comparable to the efficiency of the Delta Glider at an altitude of 50,000 metres or higher.
Using main engines it takes 1,600kg engine fuel to climb to an altitude of 50 km where drag and fuel usage are negligible.
So what is the purpose of scramjets?
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