Slightly OT - pulsejet static vid.
 

Just for some giggles here's a link to a static test of the bigger of two pulsejets I have. 18lb thrust at full bore, which is a flow rate of 340cc/minute on gas/kerosene blend. Video does not even come close to reproducing the mayhem and racket these things make, you just have to be there.

The sudden "BRA-A-A-A-A-A-A-A-A-A-A-A-A-A-P...................silence......................" when they shut off is well represented here though, if you crank the sound a bit.

[link=http://www.truerc.net/jetengine.avi]Maxjet-15 static test[/link]

MJD

RE: Slightly OT - pulsejet static vid.
 

Thank you!

bright red and the flames puking out the back at shut down.:D

RE: Slightly OT - pulsejet static vid.
 

Is there much vibration compared to a piston engine?

RE: Slightly OT - pulsejet static vid.
 

I-i-i-i-i-i-i-i-i-d-d-d-d-d- s-s-s-saa-a-a-a-a-y-y-y-y- a b-b-b-b-i-i-i-t-t-t-t m-m-m-m-o-o-o-o-r-r-r-r-e-e-e-e-. A Dynajet fires about 220 times per second which is equivalent to 13,200 pulses per minute. This guy has a lower frequency but more energy to the pulses. The V-1 engine wa mounted on a yoke with rubber bits to smooth things out.

But to answer your question honestly - having never flown a jet c/l model, I have not had the opportunity to hold a model with one running, so have not directly felt it. The thrust cycles from peak to zero or a bit negative every cycle, it can't be all that buttery smooth.

MJD

RE: Slightly OT - pulsejet static vid.
 

Bring your smaller one for a demo in June...please:):):)

RE: Slightly OT - pulsejet static vid.
 

If it works, it's coming. Simple as that!

MJD

RE: Slightly OT - pulsejet static vid.
 

Way cool!

RE: Slightly OT - pulsejet static vid.
 

At the very least, consolation prize, if the aircraft doesn't pan out I'll bring it down on the portable test stand. Good evening-time burger and soda pop fun. And might even convince a few nutbars they need one too.

MJD

RE: Slightly OT - pulsejet static vid.
 

I could not get the sound from the link/video. What am I doing wrong?

RE: Slightly OT - pulsejet static vid.
 

I wouldn't know - this is a link to the manufacturer's website. It is an .avi file, does that have anything to do with it?

The problem is definitely not due to a lack of sound..

MJD

RE: Slightly OT - pulsejet static vid.
 

No sound here too. But it has hot glow.:D

RE: Slightly OT - pulsejet static vid.
 

I got the sound...[8D]
It sounded to me like there was actually some sort of "throttle" action going on there with the engine/mount sliding fore/aft?

RE: Slightly OT - pulsejet static vid.
 

I noticed that too.

RE: Slightly OT - pulsejet static vid.
 

That was just a bird that the engine was digesting.

RE: Slightly OT - pulsejet static vid.
 

It reminds me of the doomsday machine in Star Trek.. looks about the same if you peer in the intake as it's running, I wonder if someone on the special effects team owned a Dynajet.

You know, I should try firing a bug down the intake next time I fire one up.

Actually yes, he is throttling it in this video. You can probably throttle it down about 40% in the air, but since it is strictly fuel flow the mixture goes haywire. Here, the video is supposed to demonstrate that you can throttle it down to something like 2 pounds thrust. That's fine running static, but try that with 150mph air howling through the intake and I bet it flames out instantly. I don't think they've flown their prototype yet. I spoke with someone with much pulsejet RC air time, and he said he uses the fuel flow more to adjust the mixture to his liking in the air, adding that on down lines he gives it full fuel flow, and as it slows down in climbouts or high-g maneuvers he would pull the stick back to keep the mixture from going too rich.

Speaking of throttling, I got a toy in the mail today. Gonna need a bit bigger delta than the Demon for this. Not much tho'..



p.s. PSP ought to take note here - not only will their test stand easily hold a pulsejet as seen here, but with two plywood tabs the turbine will bolt right in. Cool. Fire and noise party tomorrow.

RE: Slightly OT - pulsejet static vid.
 

.......that dynajet could be strapped to a plane with twin fins rigged up and flyable by lunch time tomorrow. I would run it mounted on an aluminum strap and get a feel for pitch control / thrust angle with a helper or two, make adjustments to get an equal amount [feel] of pitch control from neutral, then head out to the field.

RE: Slightly OT - pulsejet static vid.
 

Actually, I was just going to go for it - I get the airplanes cheap these days, and I am planning to laser cut parts for 3 or 4 conversions, anticipating a higher attrition rate than one would normally expect. Stretch the bungee cord, hold some back stick, and let 'er rip, that was my plan. Well, after careful balancing and setup of course. After watching a whack of the European pulsejet delta launches, seems most of them do that.

If I find some really tall grass, maybe I'll do light bungee "tosses" power off first. I am not entirely convinced at that point it makes any difference if the engine is on or not with regards to the outcome though.

MJD

RE: Slightly OT - pulsejet static vid.
 

I remembered to pay attention to what software it opens in on my PC, and it is Widows Media Player 11. I get sound and pic. Darn .avi files are a grab bag.

MJD