Chris91-inactive

I would really like to know what a pulse jet engine is, how it works, how much it costs to build one? Basically anything about them.

Would really appreciate it!

Chris91

CP140

Katy huh? My sister lives just down the road in Richmond... as for pulse jets. The only time I've seen them was a couple of years ago at a C/L speed trial. They are really really loud, seemed(from all the fiddling around and adjusting) to be very finicky, were a PITA to start and were really really loud(Ear plugs loud!). I'm not sure what fuel they were burning, but I was told by the guys running them that they brew their own and that some of the components were not very nice to be around.

I'm not trying to discourage you, I just wanted to tell you what I've seen/heard about them. As far as how they operate...I think they have a valve type mechanism (a perforated disc that rotates?)at the back which cycles open/closed to increase/release the pressure built up in the combustion chamber. This on/off cycling gives the pulse or buzz sound. From what (very little) I know, you have to get enough air/fuel flowing in the front end to compress the fuel air mixture, it ignites, the valve opens, the hot gasses go out, the valve closes and the cycle repeats.

One idea might be to research the WW II V1 flying bomb as I think(I may be wrong here) that it used a pulse jet once it was boosted off it's launch platform.

Good luck!

sbd-5

My Feedback: (4)

pulse jet engines are dangerous to operate in a r/c model.if not properly insulated you can set the model on fire as they run very hot and full power all the time there is no throttle.they use a spa reed valve and to pressurize the engine for starting a bicycle pump is used to sart it.they were used on controline speed planes and they were out in the open air.burnt fingers were not uncommon.one or two tried them in r/c but never caught on.there was an add for a pulse jet with a throttle on it back in the 70's that turned out to be a hoax.i think clearence lee did a reveiw on it and concluded that it was just an expensive cigar lighter.if you want to do jets either ducted fans or turbines are a better choice.

Dsegal

Do a Google search for "model aircraft pulse jet engine". I remember seeing them on control-line models in the 1950s- we would lose our club field within the hour if anyone lit up one of those things! (G)

rrragmanliam

My Feedback: (1)

Hi Chris,

Check out this link, This guy is nuts! It'll give you the skinny on Pulse Jet engines. One thing you need to know about pulse jet engines is that they are unbelievably LOUD. Not somthing you can run around alot of people. I've seen the small ones for models on ebay occasionaly.

Darren
http://www.aardvark.co.nz/pjet

britbrat

I used to own a Dynajet, back in the '50s. It burned gasoline & had a multiple-leaf reed valve at the rear of the venturi section. It was stunningly loud -- enough to cause permanent hearing loss (I know about this). It also ran so hot that the tailpipe was cherry red. It also vibrated more than a Harley Davidson.

It was started by using compressed air (from a bottle or a pump) to blow the initial air & fuel charge through the venturi & past the reed into the combustion chamber, where it was ignited by a spark plug. When the charge exploded (literally), the pressure wave slamed the reed shut & the hot gasses were expelled from the tail pipe. The tailpipe length was "tuned" so that there was a low pressure pulse created at the reed when the charge exited the tailpipe -- this pulled the reed open & drew in a fresh charge of air & fuel -- which ignited, & the whole business was off again.

Once running, combustion was self sustaining, so the spark plug did not need energizing & the compressed air source was also no longer needed. There was no throttle & no way to stop it except by fuel exhaustion/shut-off.

The mono-line speed models could exceed 200 mph at times & were run inside a metal-mesh cage.

I was dumb enough to try it on a primitive RC model with a 2-channel escapement system. The model was launched from an angled rail (like a V-1) & the end was similar -- a hole in the ground, followed by a grass fire. The model shed its control surfaces in flight, but that didn't matter because it was never under control at any time.

RedLyons

Just came across this, but thought I would offer a link with details of concept and operation.

http://en.wikipedia.org/wiki/Pulse_jet

Also, here is a link from the bottom of that page.

http://www.pulse-jets.com/

Tall Paul

I've seen experts with DynaJets start them with one push on the bike pump..
And seen others pump themselves breathless and never get a belch from the thing.
WAAAAAAAAAAYYYYYYYYYYYY TOOOOOOOOOOOOOOOO LOOOOOOUUUUUUUUUUDDDDDDDDD when they run!