On scramjets and the ramjet engine.

[rodge]

is there a way of incorporating a turbine onto a scramjet in order for it to be completely self propelled? that way it wouldn't need to be launched from another vessel.

[CaptainPanic]

I guess not... I'm sure you're not the only one interested in it by the way.

I think the turbine would be in the way if the scramjet would start to operate in its scramjet mode. All flow inside a scramjet is supersonic... and I can imagine that you do not want some turbine blades in the way of a supersonic flow.

 

Also the combustion process in a scramjet works different.

 

You could mount both types of engines on a plane, and first use one, then the other...

[spirytus]

If you're wondering about a Ramjet, Pratt & Whitney J-58 (used on an SR-71) does just that.

 

The turboramjet is a hybrid engine that essentially consists of a turbojet mounted inside a ramjet.

 

http://www.aerospaceweb.org/question/propulsion/q0175.shtml

 

Good read, check it out.

Edited December 5, 2008 by spirytus

[rodge]

I guess not... I'm sure you're not the only one interested in it by the way.

I think the turbine would be in the way if the scramjet would start to operate in its scramjet mode. All flow inside a scramjet is supersonic... and I can imagine that you do not want some turbine blades in the way of a supersonic flow.

 

Also the combustion process in a scramjet works different.

 

You could mount both types of engines on a plane, and first use one, then the other...

 

i meant that they would be seperate. i know how both work and that the blades would get in the way. but would the vessel be too heavy?

[CaptainPanic]

That I don't know... but I guess not? How heavy can an engine be? Airplanes can carry quite a lot of stuff (passengers, cargo, fuel, and unfortunately sometimes bombs) - so if you remove some of the stuff, and add an engine, then it does not become more heavy... but you can carry less.

 

I'd worry more about the differences in aerodynamic design for subsonic flight, low mach numbers and high mach numbers... but I am no expert in aerodynamics.

[bascule]

If you're wondering about a Ramjet, Pratt & Whitney J-58 (used on an SR-71) does just that.

 

The now canceled experimental Blackswift aircraft also used an all-in-one combination turbine / ramjet

[ski_power]

Correct me, but doesn't the intake of a gas turbine have to be subsonic?

[CaptainPanic]

Correct me, but doesn't the intake of a gas turbine have to be subsonic?

 

Yep. If supersonic air is compressed enough, it becomes subsonic. This compression can be achieved with a stagnant design, such as in the Blackbird (SR-71). Read wikipedia's first line about the air-inlets in the Blackbird article.