Pulse-Jet

[Charlie]

http://www.cartogra.com/servlet/LinkPho ... 6006&size=

If ye got one smaller, I wanna see it run.

[Al_Messer]

Charlie, have a look at http://users.pipeline.com.au/jcadams/designs.html if you like model jets.

[dampfwilli]

Have drawings, but in metric and german language.
Its like the old V-1 jet.

[Charlie]

Thanks Al, I have been all over the internet looking at pulse-jets, and visited my friend Earl Bailey who builds the worlds best "DynaJet" size. but can't find anything as small as the little ram jet that started this thread. I am especially challenged by things small and I have made the one pictured as small as it will go, any smaller and it won't run.

I am still curious if the little blow-tourch thing will fly a plane.

[Bryan]

I see the terms "Ram Jet" and "Pulse Jet" being inter-mixed in this conversation... technically they are two different beasts...

A Pulse Jet is like the V-1 and the Dyna-Jet, they have reed valves on the inlet side of the flame, to stop the flame moving forward... this allows it to start and run while stationary...

A Ram Jet on the other hand has no reeds and has to be moving at a given speed before it can operate... the force of the air being rammed into the intake is what keeps the flame from moving forward...

[UnkaJesse]

Dampfwilli, Bryan, Al Messer, how did we get way out here in left field talking about those extremely noisy gas burner jet engines?. As for me and my shop, I am going back to the quiet Live Steam site for now.

Unka(I guess I am responsible for this discussion in a way, since I said something about having a couple of GHQ trot line sinker weights!)Jesse

[UnkaJesse]

Just one more thang befo' I go back over to Live Steam site, I saw a set of drawings for a "Ram Jet" one time. It was basically a pair of funnel like things welded end to end and inside of a tube which was also welded. The outer tube was partly filled with gasoline and had a line to a nozzle in the centre of the smaller (front ) funnel. You heated the thing by burning a gasoline soaked rag inside the rear funnel. Result was, as has been said, a flying blow torch. Faster it ran (so it was claimed) the hotter the fire and more fuel that was vapourized, hotter the fire, more fuel etc until it was running at impossible speeds.

Unka(Impossible speeds or large explosion, whitchever came first!)Jesse

[Al_Messer]

Jesse, sounds like you have the same book/magazine I've got, printed back in the early 1950's.

[dampfwilli]

I thank God, this things are forbidden in nearly whole Europe. To loud and to much danger of firestarting in the environement.

[Peter_S]

Bryan,
From what I have read, the V1 would start while stationary, but depended on air ram effect to develop power. Thus the V1 needed to be launched at a greater velocity than its stalling speed (around 200 mph), it could then start to function properly and accelerate up to its operational speed.

They were launched up an inclined ramp, the ramp contained a firing tube running its full length. In this tube fitted a piston, the firing tube was slotted over its length, thus the piston was connected to the bomb via the sealed slot. The piston was propelled by supplying hydrogen peroxide and calcium permanganate or sodium permanganate solution into the firing chamber, this developed around 800-1000 psi initially in the firing tube, the piston accelerated the bomb up the inclined ramp
reaching 245 mph in 1 second.
The launching itself developed an instanteous 55,000 hp. The piston shot out the top of the firing tube and fell to the ground, where it was then recovered. The bomb continued on its way.

I am told that a normal way to start model pulse jets is to use a vacuum cleaner as an air supply.

[Bryan]

Peter,
I believe you're correct in what you've said, and none of it seems to contradict what I've said... They do not accelerate well by themselves... that's why the models take a few laps to get up to speed... performance increased with speed and the ram air effect... in the case of the V-1, it would have taken a huge runway to get the speed to fly, so a catapult to get it up to speed was the solution... not to mention they had limited guidance and the ramp was the basic aiming...

Starting the model ones I saw was done with compressed air (a tyre pump)...

But the point of my post was that "Pulse-jets" do run while staitionary, which true "ram-jets" wont...

[willy]

LOL sounds like a BLAST!

-willy- (still laughing)