Questions tagged [ramjet]

A jet engine that uses solely ram pressure to compress the air it takes in, rather than using a turbocompressor.

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0answers
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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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1answer
182 views

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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2answers
184 views

What is the minimum size of a ramjet?

Having recently learned that 155 mm ramjet artillery shells are now a thing, I wonder how much ramjet engines can be miniaturized. Could we see ramjet tank shells? Man-portable recoilless guns? ...
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6answers
547 views

What are the advantages of using a ramjet in an air-to-surface missile?

Which are the advantages of using a ramjet compared to a rocket engine in an air-to-surface missile? I suppose the cost rises a lot, so why do some countries use ramjets as a way of propelling ASM ...
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35 views

Adjusting nozzle shape for reduced flow rate

Suppose i have a ramjet engine, but in the combustion area i make an opening along the whole cirumference (a slit) feeding a channel, in which the pressure is the same as in the combustion chamber. ...
4
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1answer
241 views

Do ramjets use variable geometry supersonic inlets?

Ramjets are very often portrayed as super simple, I've read on few occasions that the only moving parts in a ramjet are the fuel pumps. However, turbojets operating at similiar speeds (mach 2 - mach 3)...
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3answers
183 views

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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2answers
412 views

How can a modified ramjet produce static thrust without a turbine?

A big selling point of the ramjet is its absence of moving parts (hence why it can be translated as "statojet" from other languages). However, an even bigger drawback is that a ramjet cannot produce ...
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0answers
449 views

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 and then increases rapidly near M 5. Why does this ...
6
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3answers
5k 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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3answers
2k views

Was there any progress in ramjet-powered helicopters after 1960?

It seems in 1950's some countries investigated production of helicopters powered by ramjet engines on rotor tips - examples include American Hiller YH-32 Hornet or Polish JK-1 Trzmiel. The enthusiasm ...
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4answers
3k views

What is a ramjet?

What is a ramjet? Was it used on the SR-71 Blackbird?