Hi All
In the latest issue of Model Flyer (UK Mag) mention is made of a pulse jet that runs on propane being available in the US for $80. Does anyone have any details or link for a web site please?

Cheers

Kevin

In RC the first turbines were Propane. Notice that they don't use them anymore. One of the reasons is that they are a flying bomb. There were more then one woods set afire by a crashed jet.
Don't think that i'd run out and buy one either. Oh and a kero turbine has already been flown C/L. Cant imagine having the thing spooled up more then 1/4 power, you couldn't keep up with it if you ever hit the throttle. over 300 mph is possible with a large rC jet and I understand that they restrict the plane to under that for safety reasons.
Dennis

A pulse jet is wildly different to a turbine. Pulse jets were flown on CL long before RC came out and if you'd ever heard one you'd never forget it.

Do a search on controlline speed and I think you will find lots of info on Pulse Jets and various fuels used. I beleve the current US record for controlline jet speed is just over 200 with D speed records being very close.

Dennis You are talking two very different engines and Pulse Jets are not normally able to be throttled. Although Pulse Jets have been used in many types of RC aircraft over the years with varying degrees of success. True turbines are just new kids on the block with there own set of precautions and problems not neccessarily related to PJ engines.

I still have and treasure my 1959 OS type 11 Jet but have not run it in many years. In this case it was run on white gas, but many alternatives are used today that I am not qualified to comment on.

John

Kevin:

As John said, you can't throttle a pulse jet. And I agree that propane is far from the best choice for fuel. Just too bothersome to handle.

Further, AMA has had a long standing prohibition against high pressure tanks in a model plane. Possibly the 30 psi or so for propane wasn't thought high enough to be proscribed, or maybe the early turbine fliers got a waiver.

Biggest thing against pulse jets is the sheer noise. Back in the early 60s we did a comparison in Texas. A Dynajet was actually louder than a T-33 running at 100% power.

Bill.

Well that's hardly a problem anymore Bill, I can't think of a place that HAS an operating T-33!

Well, Bill, for a more modern comparison I'm sure the Dynajet is louder than the a Phanton's pair J-79s too. The Phantom at ful AB might be louder, but not by much.

One of the very few things I know that's louder than the Dynajet is a Saturn 5 at liftoff.

Bill.

I have a set of prints and have been working on building one for a while. The tube has me stuck for now, I just don't feel like making all the tooling needed to spin it.[&:]

Actually I well know what a Dynajet is having had a few of them myself as well as the OS and even the M.E.W. I really didn't read the post correctly and replied to a misguided understanding of what I'd read.
As to the noise of a Dynajet it is actually a low frequency type and as has been discovered low frequency has the ability to transmit noise or sound ouve\r tremendous range. Given that we have had a few of them run up at our field within the last few years it Always brings a smile to my face to hear one of them run.
Dennis

for the record, his question was:
"In the latest issue of Model Flyer (UK Mag) mention is made of a pulse jet that runs on propane being available in the US for $80. Does anyone have any details or link for a web site please?"

not
How flammable is propane?
Can someone give me the history of pulse jets?
How loud is a pulse jet?
How does the AMA feel about compressed fuels?

sorry to flame (pun definately intended) but i'm researching the same thing and already know about the hazards and noise, but would like to buy or build one anyway.. and it seems every thread i come across on the net has this same information. off topic history of jets and "look at how much i know" as opposed to answering anything.

well, so i can say i contributed SOMETHING to this thread, heres a link i found that has ALOT of detail on both valved and valveless pulsejets, and even some valved that he claims can be throtled thru a wide power range. plenty of plans and detailed writeups.. plus plans for a no-weld pulsejet... tho i wonder how well it works.... (however its not USA based...)

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

Hey Mr. one post. pm me and I will send you the plans to build for your bad self. Then you can contribute your vast experience.[&:] What the heck I will even throw in the reed since I have a few extras burned out.

The only propane pulse jets I have seen have been valveless. Many years ago (when Dynajets were in hobby shops for under $100) I do remember someone marketing a valveless propane pulse jet. I dont know if anyone ever got one to fly but do know they were also sold as jet demonstrator engines to high school shop teachers. If I remember right the thrust was actually quite low... maybe 2 or 3 pounds.
Bob Furr

Dennis,

Did you actually get that M.E.W. to run?

George

ama c/l jet speed record is 204.93 mph held by waltemath and mathison 12/7/2002 not only did i see this record set i was the pilot very cool thing to do on a weekend of fun in the sun. joey

No, but not for lack of trying.
Dennis

I never heard of anyone getting a Minnesota Engine Works (MEW) engine (?) to run.

Bill.

Dynajet and a Dynajet Red Head.
" What hearing loss ? "

I have a dyna jet and I am looking for a head for one ,,, anybody want to part with one? also , good luck making one ,, Its a lot of work , and time ,

jason,

http://www.airtoi.com/pulse.htm

see for yourself....answers fuel and speed questions...

I would have to get it to pass our state Auto Emissions first ?

A correctly designed pulse jet is 90% throttable. The German V1 was 60% throttable in the beginning then the Germans later made some changes to the engine so it was 90% throttable. It is very easy to start a pulse jet at 10% throttle then throttle it up to full power. The compression ratio of the German V1 as 2 to 1, most hobby engines like the Dyna Jet have a compression ratio of 4 to 1. The higher compression ratio makes the engine harder to start, more fuel efficient, and shortens the live of the reed valves. Propane is 185 psi at room temperature and gasoline is a better fuel than propane for hobby engines. Low compression pulse jets will run pretty good on propane but gas is still better. Here are links to a model pulse jet engine I built with Argus type reed valves. I built the Argus valves just to prove it could be done on a small model. This is not a model that could be used on an airplane it is too heavy. I don't care how heavy they are for testing only.

Gary can't see the pictures just takes me to the photo bucket website.

First Dynajet I ever saw, was demonstrated in my high school Gym. The demonstrator told us to be quiet, and to listen carefully because it wasn't very loud. When that thing lit off, everyone in the Gym went into shock, and instantly covered their ears! It was the loudest engine I had ever heard !!!

Years later a friend flew one on a control line airplane, and I pitted for him a time or two. No ear muffs were available at the time, but they are absolutely necessary if you value your hearing. We stuffed cotton in our ears, but it didn't help much.

Many years later, I heard a very similar noise coming from the armament school area, on Lowry AFB in Colorado. It was a mile or more distant from my class room, but the noise was awesome (and vaguely familiar). They were test firing one of their Gatling guns!

Bill

A pulse jet is wildly different to a turbine.

___________________
Nathalie
need a job

Here is my next pulse jet engine producing 10 lbs of thrust.

http://www.youtube.com/user/Lowracer.../5/u2apj002QwY