Kmot

My Feedback: (24)

No props. Flapper valves!

380 KPH.... That's 236 miles per hour.

It's worth watching if you are a speed freak:

http://youtube.com/watch?v=Z2fbFNgkw2U

erazz

I loooove pulsejets!


Noisy, red hot, loud, noisy, no throttle, deadstick landing, noisy, noisy, takes 2 people to start, you can see up the tailpipe, very loud and noisy.


And yes. I like the noise

TEAMERICA

My Feedback: (77)

. . . and don't forget all the starting equipment. . .

[link=http://youtube.com/watch?v=XbM1RndVM50]http://youtube.com/watch?v=XbM1RndVM50[/link]

proptop

My Feedback: (8)

It kinda sounds like one long, continous (really loud ) whoopie cushion...

That thing is really cool though!
What sort of fuel system do they use to provide it with fuel? I have read that they (at least the older ones ) are very sensitive as to fuel supply, or they'll flame out. It must be pressurized, right, but how/where? Must be a regulator in the system too...

Gonna haveta google "Pulse Jet" now I guess...

TEAMERICA

My Feedback: (77)

Only one moving part. Venturi fuel draw just like our glow engines - but no tank pressure needed.

Methanol is preferred due to cooling effect - but gas will work.

Watch this:

[link=http://www.youtube.com/watch?v=IJqkHJ2zWPY&NR=1]http://www.youtube.com/watch?v=IJqkHJ2zWPY&NR=1[/link]

Very informative. . .

vicman

My Feedback: (10)

Here is a picture for ya.[8D]

combatpigg

My Feedback: (3)

Ingenious engines. I read some time ago that a use for these engines on a larger scale is / was to keep citrus orchards from freezing.

vicman

My Feedback: (10)

All the fruit had a frown if they did. They are flippin loud bro.
I really want to build one at some point in my life.

Kmot

My Feedback: (24)

Nah, they use smudge pots. They look similar in a way and are heaters, but don't blow like a rocket engine.

skull1971

V1 "Buzz Bomb"

Don't the control line speed guys use those engines too? 10+ on the cool factor.

proptop

My Feedback: (8)

A lot more info here too...[8D]
http://www.beck-technologies.com/

MJD

My Feedback: (1)

Yes they do - for that and dispersal of chemicals. Curtis Dynafog is still in business - these people made the Dynajet, and were founded in 1947 according to the website.

http://www.dynafog.com/home.html

My winter project is an airframe for an 18lb thrust pulsejet. Magnums aren't fast enough..

MJD

Julian537

My Feedback: (9)

MJD,

18lb thrust pulse jet?? WOW that is serious. Dont be to close to the border flying that.
The U.S. may shoot it out of the sky.

Are pulse jets legal to fly in the U.S.??

combatpigg

My Feedback: (3)

MJD, keep us posted about your Dyna-jet project. The ones that I have seen were very tempermental used in C/L speed. I'll bet they were "optimized" for the event. The original ignition for starting them were Model T Ford coils.
I'm glad to hear that there is a guy who is carrying the torch and seems to have mastered them for model use. His prices seem very reasonable.
They put out such a roar and guzzle fuel, it always struck me funny that they would use giant sized Dyna-jets in orchards.
Our LHS owner has one mounted on a .35 sized Ring Master C/L stunt plane.

HighPlains

My Feedback: (1)

I think the Dynajet only puts out about 4 lbs of thrust. My dad still has the one he flew in the early 50's. He mentioned about a week or so ago, that he would like to hear it run again. It's still mounted to one of the two C/L airframes built for it back then. There is enough asbesto on them that a crash would have to be considered a EPA Superfund site afterward. Hmm.......

MJD

My Feedback: (1)

Sure they are legal to fly, they are used in C/L speed in the Jet category. They are limited to the dimensions of the Dynajet, i.e. 1-1/4" tailpipe, and while in the past people used fuels containing large amounts of nitromethane, the speed event is now, AFAIK, regulated to a fuel consisting of methanol and MEK. As far as R/C pulsejets under AMA.. hmm.. not entirely sure, but I think that I saw a rule stating they could not be enclosed. Why is beyond me, as turbines run pretty darn hot too, but perhaps when that rule was written it was in the early to pre-commercial turbine days. In Canada, the MAAC regards turbines and pulsejets equally and, sensibly, they are governed by the same regs, i.e. rigid tanks versus IV bag bladders for example (bladders in rigid outer cases are fine). Bladders are the ultimate tank for these (surprise they also rock for glow engines) as yes, a bubble can cause it to die. I believ eturbines are a bit particular in that sense though how much so in relation I don't know. Pulsejets can start fires, turbines can start fires, so can other things. Noise.. well, heh heh.. you better find a remote flying site becuase brother they are freakin' LOUD! A Dynajet sounds like a bike with open pipes backfiring at 13,200 rpm. The resonant frequency is of course determined by chamber length and design, the Dynajet resonating at about 220Hz. The big guy is correspondingly lower.

CP: Yeah, the C/L speed guys often run larger venturis and intake designs optimized (in their opinion sometimes.. experimenting abounds) for high speed, and they as a result can be more finicky on startup and launch. The specific fuel consumption of a Dynajet size model on gasoline is pushing 3 ounces per minute. On nitromethane/methanol fuel, AFAIK they go through 6-7 ounces on startup, quick launch and a speed run of run up plus 10 laps. I think that equates to around 12 ounces a minute. On methanol/MEK I preszume the mixture is less fuel rich and the specific consumption is lower. These numbers may not be bang on, I don;t fly C/L speed, but from the figures I have read/seen and bearing in mind the stoichiometry of those fuels they seem about right.

The 18lb guy is really cool - it is very light for it's size, at about 900 grams, and uses a turbine fuel pump and speed control for a semblance of controllability. Fuel is a gasoline/kerosene blend. In the Netherlands they fly pulsejets this size on deltas about 1.2 m or so in span (42-44") and hit speeds up to about 400 kph. Google "Team Helmond" for some pics. There is another site that has some CL speed video and RC video, but at home here I am dialup until I go DSL this week or next, and when I do I can find it again.

As to the airplane project, yeah you bet I will post some stuff when it gets under way, likely in 4-8 weeks when I finish some reno work and fixing up my workshop. Canada = depending on latitude 4-6 months of hopefully good flying weather plus 6-8 months of repair and build time. Likely the same for the upper states too

MJD

rmenke

My Feedback: (13)

Kmot:

What the heck did you start up this time??? Thank god they are not available in the local hobby shop. And-----no don't want to know where you can buy one. We flew one of these things at the school yard in the 50's. Twice. The black and whites were there the second time before it ran out of fuel. ENJOY

MJD

My Feedback: (1)

Luckily the one site where I can fly is at the back boundary of an old military airport with little around it except gravel pits and farm fields. They have jet fliers there already and the club pres thinks flying the pulsejet there would be cool. Mind you. we'll see how his opinion wavers when he hears it for the first time though..

Pulsejets are a perfect sidebar for an extreme speed forum IMHO - more so than pudgy ARF jets struggling to crack 100mph, which are really moderate speed prop planes.

MJD

vicman

My Feedback: (10)

I really hope that is not a slam at the F-20s most of us love.[X(]

Kmot

My Feedback: (24)

rmenke: Can you just picture a pylon race with pulsejet powered airplanes? Man, that would make a racket but be awesome to witness! [sm=thumbup.gif]

MJD

My Feedback: (1)

Nah, F20's don't qualify as "pudgy". F4's, maybe.. But I like them too.

Pylon racing.. whoo brother, hard to tell what would be more important, hearing or head protection. Mind you, the head protection might be academic, like using denim for a flak jacket.

MJD

vicman

My Feedback: (10)

Good answer!
I would hate to need to make a side trip to Orangville next Monday for some conversation!
Yep, I will be in Toronto Monday.

Kmot

My Feedback: (24)

What a hoser, eh!