|Ian Usmar||08/05/2019 20:29:23|
|52 forum posts|
Is there anyone on here who is an expert in Pulse Jet Carbs ?
|Roy Vaughn||08/05/2019 21:43:08|
|5 forum posts|
Try the forum on the Barton web site:
|Andrew Tinsley||08/05/2019 22:01:15|
|899 forum posts|
They don't have carbs as such. Just a very narrow aperture for the fuel and usually a compressed air source to start them. The difficulty is getting the diameter correct for the ambient temperature and pressure. Quite an art form in getting this correct.
|Martin Hamilton 1||08/05/2019 23:39:19|
|102 forum posts|
Have a word with Barrie Lever on this forum, i believe Barrie is flying some pulse jet control line planes. If he can't offer advice i'm sure he probably knows someone that can.
|Speedy Builder5||09/05/2019 06:48:14|
|1790 forum posts|
I have the plans from the Model Aero Engine Encyclopedia 1959 showing the Brauner Pulse jet. PM me if you want a copy. My problem is finding someone who could laser cut the petal valve disc from 0.010" - 015" shim steel.
|Tim Stevens||09/05/2019 17:14:44|
1048 forum posts
Clever things, pulse jets. You start with a working two-stroke single, with a reed valve inlet and tuned resonant exhaust system, and you take away the engine and just join the rest together. Exhaust dimensions limit the frequency, so with a model I guess the sound is not at all reminiscent of a V1?
Reed valve petals can be made by spark erosion, electro-etching, and in extremis, nail scissors. But why not a flutter-box as used in the device mentioned above?
|Speedy Builder5||09/05/2019 17:30:16|
|1790 forum posts|
Yes Tim, I ran mine up on cup final day one year. Our neighbour who had been bombed by a V1 came running outside in sheer terror.
|Oily Rag||09/05/2019 17:43:01|
22 forum posts
You can use the reed valves from 2 stroke motorcycles, depending on what size you want to build you have the choice of either 80cc kiddies motorcrossers reed valve blocks through to 450cc single cylinder Pro Crossers reed blocks. These reeds are either stainless steel, titanium or of a resin based material. The fuel delivery system is best served by a spray bar arrangement with a needle jet trimming device for fuel flow, ignition by a trembler coil feeding a 14mm spark plug, and on the one I built with some work colleagues many years ago (30!) we had a variable 'exhaust tube' which changed the tuned frequency and allowed us to 'pitch' the outlet sound. Basically the exhaust was a slow tapered tube (~8 to10 degree included taper) from about 3" diameter out to 5" diameter with a reverse cone megaphone reducing it to about 1.5" diameter. The variable length was a sliding arrangement on the 1.5" tail pipe.
As has been mentioned above you will need some compressed air to start it and a hand squirt fuel bottle to encourage 'first fire'. Have a fire blanket and fire extinguisher to hand! (in case of a back fire - but with the reed valve block it should be pretty safe)
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