Atchtoong! Vergeltungswaffe 1 engine runs...

[bdk]

Well, a (Ford built) JB-2 Loon engine at least... An exact copy of the V-1 engine:







And it does have thrust! It pushed the trailer and the full size SUV it was attached to (in nuetral of course):





P.S. I only posted photos with exhaust flame showing otherwise there's no other way to tell it was running...

[51fixer]

Must also make noise!
Rich

[n5151ts]

[Steve Nelson]

How'd you get them to let you paint your name on it? Seems like the paint would burn off after a few runs.

SN

[K5DH]

Coolness!

[JDK]

OK. So how does this work, then? I understood that the pulsejet needed forward movement to ram air into the intake - which is why the V-1 was ramp launched to get engine (not flying) speed?

Or is it modified? Or very inefficient at low speeds but still runs? (Which implies that if it manages to get that SUV above 'x' speed, it'll take some catching...

Yeah, running jet engine pics are a pig, aren't they?

[Dan K]

Oh yeah!

And for those that need a little sound check:

http://www.youtube.com/watch?v=5U-grFuXZ9U

[Dan K]

Heh heh...gotta' watch...more youtube pulsejet Luftwaffe:

http://www.youtube.com/watch?v=3ScVuXyu ... re=related

[bdk]

The paint is a special ceramic "bdk" paint that won't burn off...

Yes, it is loud. Very loud.

No forward speed required, just lots of fuel. A ram jet is the one that requires forward motion (and quite fast at that) to run.

Basically it is a tube with shutters (one way valves) at one end. When the mixture ignites the fireball gets pushed out the back, creating a vacuum in the duct which causes the shutters to open and draw in more air. The length of the duct causes a resonant wave to come back into the combustion chamber to create compression. Combusion takes place again and the cycle repeats. A spark plug is used for starting, once up to temperature it should run without a spark. Primarily the length of the duct dictates the pulse rate. They are not easily throttled because the resonant forces in the duct are actually quite weak and the duct pressure is low.

There's quite a lot of info on the internet about pulse jets. The valveless ones are quite simple to build in fact and one was featured on the cable TV show Junkyard Wars.

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

http://aardvark.co.nz/pjet/scrapheap.shtml

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

Last edited by bdk on Sun Aug 17, 2008 10:38 pm, edited 2 times in total.

[JDK]

No forward speed required, just lots of fuel. A ram jet is the one that requires forward motion (and quite fast at that) to run.

Basically it is a tube with shutters (one way valves) at one end. When the mixture ignites the fireball gets pushed out the back, creating a vacuum in the duct which causes the shutters to open and draw in more air. Combusion takes place again and the cycle repeats. A spark plug is used for starting, once up to temperature it should run without a spark. Primarily the diameter and length of the duct dictate the pulse rate. They are not easily throttled because the resonant forces in the duct are actually quite weak and the duct pressure is low.

Thanks bdk, got my pulse jets and ram jets muddled. Guess that's why I don't turn spanners.

[airnutz]

Basically it is a tube with shutters (one way valves) at one end. When the mixture ignites the fireball gets pushed out the back, creating a vacuum in the duct which causes the shutters to open and draw in more air. The length of the duct causes a resonant wave to come back into the combustion chamber to create compression. Combusion takes place again and the cycle repeats.

Great post BDK! I spent a good chunk of a day awhile back revisiting pulsejet technology and history.
An amazing detail about the combustion cycle you explained, is that it occurs several hundred times per second.

How did they start this one? I've read the larger engines often used another gas(propane, etc.) or a
fuel pump to inject the running fuel into the combustion chamber to start them. Just curious. Neat schtuff!

[bdk]

The reason they couldn't drive the rig around the airport was because the extension cord to run the fuel pump wasn't long enough.

I think the sequence was ignition and then fuel. That's it. They had a leaf blower to blow out any fires from pooled fuel. Sometimes it would kaboom on startup, sounded like a stick of dynamite in a metal trash can- not that I've heard one of those.

[The Inspector]

When I was in A&P school they had one and second year graduating students got to fire it up, GOOD GRIEF DID THAT THING MAKE NOISE!!!!!!
LOud roaring over note with an under tone high pitched sort of whooop very low. A few blocks away was a farmer who's chickens would freak and stop laying so the county made the scholl stop after a couple of years,that was over 40 years ago and I don't know where it went, probably to the scrapyard because it was 'just old junk stuff'

[airnutz]

The reason they couldn't drive the rig around the airport was because the extension cord to run the fuel pump wasn't long enough.

...for the lack of a generator, no joy ride...

I think the sequence was ignition and then fuel. That's it.

Yep, that's how I understand it. They use a multi-spark ignition..once she fires...MSD is switched OFF and the
combustion cycle is self supporting as long as the fuel lasts.

They are critical in their power output when you mess with exhaust tube length and intake orifice...if
you could adjust those "on the fly", you could crudely achieve a throttle. That's what I gather...

[Tulio]

When I was in A&P school they had one and second year graduating students got to fire it up, GOOD GRIEF DID THAT THING MAKE NOISE!!!!!!
LOud roaring over note with an under tone high pitched sort of whooop very low. A few blocks away was a farmer who's chickens would freak and stop laying so the county made the scholl stop after a couple of years,that was over 40 years ago and I don't know where it went, probably to the scrapyard because it was 'just old junk stuff'

I'd said that it would be safe to start that engine again. All "them" chickens must be long dead by now. : )


Saludos,


Tulio