Pulse Jet in hindsight.

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Nodeo-Franvier

Airman 1st Class
134
28
Jul 13, 2020
Pulse jet us the simplest and most cost effective form of jet but is was difficult to use. From modern perspective what is it good for? Would strapping it on a conventional Jet plane beneficial? If not how should it be use?
 
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Pulse jet us the simplest and most cost effective form of jet but is was difficult to use. From modern perspective what is it good for? Would strapping it on a conventional Jet plane beneficial? If not how should it be use?

The are reedless or valveless pulse jets now.

The problem with the Argus pulse jet was that although it could operate at zero speed its thrust could not be varied much creating low speed handling difficulties. Is suspect low speed thrust was also a little lower.

Experimental versions of the V1 achieved 485 mph according to Reuters book.

One problem was that although the V1 was far faster than any fighter at its cruising altitude the valves deteriorated after 10-15 minutes which allowed interception. This probably would have been fixed but there was little time.
 


More interesting were the inductor ramjets being worked on (in WW2 Germany) and elsewhere. A small rocket in the centre of the ramjet induces an airflow which starts the ramjet at zero speed. The rocket can be turned of after speed is reached. Another version just used fuel heated by wrapping around the fuel line around the ramjet to use the pressure of the fuel to induce the airflow.
 
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There is no reason (I think) that a pulse jet could not be used for additional thrust, for shorter TO distance/greater TO weights, or in flight for bursts of speed. The main problem (I think) with using pulse jets for any other purpose (on a non-experimental aircraft) would be the appalling fuel efficiency. A pulse jet uses somewhere around 25x the amount of fuel that a typical WWII gasoline fighter engine used (Merlin at 3000 rpm and +9 lbs boost for example) for the same effective thrust, and at least 10x the most fuel efficient centrifugal-turbine jets of the time (Derwent I for example).
 
That inefficiency was used to produce a massive exhaust flare which could be seen from launch by Mosquito night fighters.
 
The noise is considerable, however small pulsejets are still used occasionally on model airplanes. Examples can be found on You tube. I ran mine just this New Years eve. New years and 4th of July are the only times can be done reasonably in the neighborhood. Although one New Year in the 60s, with considerable celebration going on near midnight, my wife came out and said the lady behind us called to ask if we were creating a nuisance. My wife told her "I don't think so. My husband is just running his jet engine." I asked what she said and was told "nothing and after a few seconds, hung up." After all it is only 21 inches long.
 

As long as your jet engine does not power a mini Fi 103, the neighborhood is safe.
 
V1 Flying Bomb on test - 1964 Press photograph | eBay

well... is that you on the left Ed?

 
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