Questions tagged [scramjet]

A jet engine that uses ram pressure to compress incoming air, and where the airflow throughout the entire engine is at supersonic speeds.

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Is it possible for a ramjet to start from 0 velocity?

I was wondering if it is possible for a ramjet to start from 0 velocity. I know its working principle and all, but is there any missile or aircraft that completely uses ramjet, with no rotating part ...
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19 votes
3 answers
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How efficient is a Scramjet?

I searched about the subject, but I couldn't find any place where the overall efficiency of the scramjet is compared to the other types of engines. All they say is how the "Scramjet is more ...
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Would a ramjet be able to fly at 1% of sea level atmosphere and pure oxygen? [duplicate]

1% (0.01 atm) of the sea level pressure is a bit less pressure than at the SR-71 Blackbird's highest altitudes. If all that atmosphere was 100% oxygen (instead of 21%), would a (sc)ramjet still be ...
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11 votes
3 answers
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Is the compressor required on jet engines? Can air be rammed into the turbine?

In the context of a common airliner (say Boeing 777), when the airplane is on the ground, and the turbines are on, air is getting sucked in and compressed/bypassed. The engine has to do work to ...
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2 votes
1 answer
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why does the flow need to decelerate (by a thermal throat) in a scramjet?

I have a question about the thermal throat in a scramjet. From my textbook: "The scramjet, on the other hand, needs an area increase as combustion occurs. For this reason, on the scramjet the ...
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How can the 3M22 Zircon receive commands at high speeds?

According to its Wikipedia article, the scramjet-powered 3M22 Zircon missile is capable of achieving speeds of up to Mach 9, at which a plasma may be created around the missile. The article further ...
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-2 votes
1 answer
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Rocket Thrust vs Air breathing jet engine why is a rocket better [duplicate]

What are design dynamics that give the rocket engine higher thrust than an air breathing jet engine of similar size in comparison to a turbo jet engine, turbo fan engine, high by pass turbo fan engine,...
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4 votes
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Does/Can combustion instabilities occur in SCRAM jet?

I was told that combustion occurs at Supersonic speeds in SCRAM jet. So acoustic disturbances/ pressure fluctuations can't travel into incoming jet stream. Does this avoids combustion instabilities in ...
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Could liquid alkali metal fuels be used for ramjet/scramjet propulsion?

In particular, I'm thinking about lithium, but sodium could be considered as well. Lithium has low molecular weight, very high propellant density, and low melting point. At sufficiently high ...
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6 votes
2 answers
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Could hydrazine be used as a scramjet propellant?

Hydrazine is used a monopropellant in Satellite OMS rockets. But interestingly enough, it's highly exothermic decomposition into ammonia, nitrogen, and hydrogen provides heat for an endothermic ...
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3 answers
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What mechanism or design aspect prevents jet blast from escaping the front of a Ramjet or scram jet?

Enormous air pressures result in the thrust of a Scram jet or ramjet engine, more so the pressure required to drive the aircraft forward at supersonic and hypersonic speeds. Given that these engines ...
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2 votes
1 answer
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What technical problems stopped scramjets from being used on hypersonic aircraft?

I have been researching hypersonic aircraft and scramjet engines after running a few calculations looking at ramjet/rocket hybrids for making single stage to orbit vehicles. After doing the analysis ...
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Is there a viable alternative to liquid hydrogen as a fuel for scramjets?

Given the difficulty and complexities of storing liquid hydrogen for commercial flight and the high velocity of air passing through a scramjet, do other types of fuel provide a feasible alternative ...
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2 votes
0 answers
92 views

What is the operating temperarature of a scram jet at its theoretical maximum speed?

What is the operating temperature of a scram jet at its theoretical maximum speed of Mach 24? For those with access to a simulator and do such simulators exist and are they possible? Given this ...
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7 votes
2 answers
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What is the effect of Mach number on efficiency, thrust and specific fuel consumption of a ramjet engine?

My graphs show that overall efficiency and thrust first increase, reach a peak and then fall in the supersonic range (M=1-5) whereas SFC first drops and then increases rapidly near M 5. Why does this ...
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8 votes
3 answers
10k views

Are there any planes that have ramjet or scramjet engines?

Are there any planes that have ramjet or scramjet engines? If so, how did they reach the required mach speed for the engines to start functioning?
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