Talk:Ramjet

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[edit] Great new graphic, but

The new graphic is great but it couldnt be hello good samaratin in two ways. 1) it lacks a flameholder, usually just drawn as a zigzag line. 2) Most importantly, the design shown is supersonic, therefore it needs a converging-diverging exhaust nozzle to induce supersonic exhaust.

Finally, a subsonic rendition would be nice, with simple diverging intake diffuser and converging exhaust

Comment 2) is not strictly true! Even a convergent nozzle can generate a supersonic exhaust plume. The gross thrust is calculated at the throat as follows:

Fg = w.Vj/g +Aj(pj-pamb)

The first term is the momentum thrust, which generates the bulk of the thrust, whereas the second term is the residual pressure thrust. Ideally, a convergent-divergent nozzle will expand the flow so that there is zero pressure thrust (i.e pj=pamb) and all of the thrust is from the momentum term. Depending on nozzle pressure ratio, a con-di nozzle produces more thrust than the corresponding convergent unit. On a rocket motor the advantage is very large, because of the high nozzle pressure ratio. The advantage on a turbojet/turbofan is usually marginal, because nozzle pressure ratios are quite low. Ramjets are somewhere in between. :) Burbank 17.09 January 9 2006 (UTC)

The picture of the "low speed Ramjet" is worthless. That is NOT a ramjet. It's more of a space heater than anything else. A ramjet produces thrust, while theirs does not. It does not operate like a ramjet in any sense of the word. I removed the picture of it since it is misleading and doesn't contribute anything to an article about ramjets. Maybe it will be useful in an article about space heaters.