h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I linked to this Entry from my Entry on the Gloster Meteor at A10780986; but realised that it does not mention pulse jets. A pulse jet has a series of hinged vanes at the front end and needs a much lower speed, possibly as low as 50 mph to work (compare this with the ran jet which requires a minimum tof 200 mph) The hinged vanes remain open until the working speed is reached.
Fuel is injected into the compressed air stream and ignited. The explosion shuts the vanes, allowing the hot air to escape only at the rear, pushing the craft forward. The whole cycle then repeats itself. The pulse jet needed to be started up and running before launching.
The pulse jet (used on the V-1 'doodlebug' missiles, launched against GB in WWII) were less popular than the ram jets used on the V-2 rockets,because of its exhaust note-similar in sound to a single cylinder motor bike - and its need to be tuned in order to work.

Fascinating. Update on this entry due, methinks...

SoRB

Have any valveless pulsejets been made so they can shift into a ramjet cycle when they reach to operative speed? That could be an alternative to rocket boosting because of air-breathing benefits, & over a turbojet because the purpose of simplicity's not defeated.

Dear Big Al, the information you have given here is in fact incorrect.
Let me explain a couple of things here for you, its a facinating subject, and we'll only be scratching the surface.

There are two types of pulse jets,
1a-) Valved (A valved engine has no hinges instead uses a series of -typically spring steel- valves that bend to open then slam shut upon combustion. Very much like a 2 stroke engine valve plate. However they generally burn up and break after 30 minutes of operation...give or take.

1b-) Valveless. Has no moving parts what so over, effectively an extremely well tuned harmonic organ operating at 2000K, and an indefinite operating life free from maintenance/.

2a-) Both engines types perform well at static, (zero air speed) as speed increases efficiency does increase however the valveless engines will produce a higher top end as valved engines max out their ability to breath through a frontal intake at approx 400 mph.

2b-) The "hinged vanes" do not remain open! This is not how they operate, they oscillate at a frequency governed by the size (diameters and lengths) of the engine and the type of fuel being used... this is regardless if running at static or not.

V-2 Rockets did not have ramjets they were a pure fuel/oxidiser rocket.

Dear
athodyd: A ramjet / pulsejet dual burner engine was developed by Messerschmitt designation "Type 06 and Type 07" pulse-ram jets. At 3 meters long each they were extremely loud and very hard on operating personnel. To my knowledge they were never flown.

Hope this helps.

Regards,
James Irvine,
Irvine Aeropulse Australia.

Pulsed combustion specialists.

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