SR71 Pulse Jet Engine

[Rocket Man]

I built this Pulse Jet Engine it runs on Gasoline or Alcohol or Gas/Diesel mix. It produces 10% more thrust on 25% diesel/gas mix and about 35% more thrust on Methyl Alcohol. It starts easy at 20% thrust and can be throttled up to full power with a needle valve. Ram air from forward speed gives the engine about 30% more thurst with added fuel. I built the engine body from muffle pipe and EMT conduit. The engine has an aluminum head and fuel injection directly into the combustion chamber. The reed valves are .010" blue spring steel. I cut the reed valves with avation tin snips regular type tin snips will not work.

Static thurst is 4 lbs running on propane, 5 lbs running on gasoline, 5.5 lbs running of gas/kerosene, 5.5 lbs running on gas/diesel, 7.5 lbs running on 100% Methyl Alcohol, 7.5 lbs running on 95%/5% Alcohol/water. With 200 mph Ram Air and a second fuel tank designed to give the engine more fuel as it picks up speed its 7 lbs on gasoline and 10 lbs alcohol.

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[ame]http://www.youtube.com/watch?v=s5KInr3C9vQ[/ame]

 

[compspecial]

Brilliant,Rocket man,and something a little different! Seems like a very steady runner.
Stew.

 

[charlesfitton]

The pictures are "blocked" at work, but thanks anyway...where do you source spring steel? My local metal supplier just laughs..

 

[Rocket Man]

You can order Blue Spring steel from several different companies. Prices range from $29 to $43 for 2 sheets 6"x24". All the metal is made by the same manufacture only difference is the company that sells it has a different price. Spring steel comes in flat sheets and rolls. I like the flat sheets. Type the words, .010" blue spring steel, in the search box then click. OK. You can buy blue spring steel from the following 3 companies. Type in the item number in the search box to place an order.


MSC. http://www1.mscdirect.com/cgi/nnsrhm

.006" Blue Spring Steel. Item number #00053066 price $27.66 per 50" roll.

.008" Blue Spring Steel. Item number #00053082 price $28.71 per pack 2 flat sheets.

.010" Blue Spring Steel. Item number #00053108 price $29.23 per pack 2 flat sheets.

.012" Blue Spring Steel. Item number #00053124 price $29.75 per pack 2 flat sheets.



WW Grainger. http://www.grainger.com/Grainger/wwg/start.shtml

.006" Blue Spring Steel. Item #3L715 price $28.50 per 50" roll.

.008" Blue Spring Steel. Item #3L719 price $43.30 per 2 pak 2 flat sheets.

.010" Blue Spring Steel. Item #3L721 price $40.55 per 2 pak 2 flat sheets.

.012" Blue Spring Steel. Item #3L723 price $29.95 per 2 pak 2 flat sheets.



Mc Master Carr. http://www.mcmaster.com/#

.006" Blue Spring Steel. Item 9503K15 price $18.00 per 50' roll.

.008" Blue Spring Steel. Item 9503K17 price $18.20 per 50' roll.

.010" Blue Spring Steel. Item 9014K22 price $14.56 per 1 sheet.

.012" Blue Spring Steel. Item 9014K61 price $11.78 per 1 sheet.

 

[pcw]

nice! i see you cut the petal valves. why not etch them? much easier and they dont warp at all. all you need is bucket of salt water, battery charger stainless plate for negative and connect the positive to the reedvalve plate and off you go (bit more prep work involved, but quite simple)
Pascal

http://www.aardvark.co.nz/pjet/makevalves1.pdf

[ame]http://www.youtube.com/watch?v=jEnNMTMZadw&feature=related[/ame]

 

[Rocket Man]

nice! i see you cut the petal valves. why not etch them? much easier and they dont warp at all. all you need is bucket of salt water, battery charger stainless plate for negative and connect the positive to the reedvalve plate and off you go (bit more prep work involved, but quite simple)
Pasca

I tried salt water etch it takes too long. It takes several hours work to prep the metal, paint, dry, scribe, etch, sand and the edges are as ruff as a corn cob. Then all the edges have to be sanded on the belt sander that takes more time. I end up with about 2 hours work in each pedal valve.

I scribe the valves on the blue spring steel, then cut out the piece, then drill the holes, then tin snip off the unwanted metal. I have 5 minutes work per valve if I make about 10 parts at a time. They are ready to use if I do all the cutting from the same side all the ruff edges are on one side the other side is smooth. I have 40 hours of run time on some pedal valves and they show no signs of getting hot and no damage.

 

[pcw]

yeah it takes some time, but i find they last longer when etched too. i fly a model with a pulsejet and the etched valves last at least twice the time a cut one does. at least in my engine.
Pascal

ps, only shame is that i am only allowed to fly on one place here in netherlands, and occasionaly on model airshows. toooooooo loud

 

[Ken I]

Rocket Man - love your pulsejets.

pcw - thanks for the tutorial on etching - I didn't know it was that simple. Karma.

Question - up to what thickness is practical - in what materials.

Regards,
Ken

 

[Omnimill]

I read somewhere that Pulse Jets were banned for use in model aircraft in the UK. Is this still the case? As I understood it they were regarded as a fire hazard. If not, how small can you make them ... ;D

Vic.

 

[Swede]

Another source for a variety of spring steel (not completely sure about the quality, but it seems like good stuff) is to cannibalize a feeler gauge. A cheap gauge gives you an assortment, and you can find the thickness that works best.

 

[pcw]

I read somewhere that Pulse Jets were banned for use in model aircraft in the UK. Is this still the case? As I understood it they were regarded as a fire hazard. If not, how small can you make them ... ;D

Vic.

we have more and more restrictions on pulsejet or jetengine models over here. main reason is the noise. i did fly in UK this summer as a demonstration so it is possible on special permits from organiser. our club has a model-airshow every summer, and we are allowed to fly two runs of max 5 minutes with two pulsejets. spectators love it, but most will admitt its getting painfull for the ears after 3-4 minutes of low pass high speeds pulsejet noise.

i do have alot of old and newer plans for pulsjejet engines, form quite small to big ones. can email them to you or put them in a place for you to download if you want them although most of those plans are free to download and find on the net.
Pascal

ps, this small
[ame]http://www.youtube.com/watch?v=zn4YVYdp8lE[/ame]

 

[Omnimill]

Thanks for that. I reckon the noise would upset some folks so maybe I'll leave it for now!

Vic.

 

[pcw]

a running pulsjejet wakes up the dead, well at least close to that noiselevel