Moderator: Mike Everman
2 posts • Page 1 of 1
I bought a Zanin Z26 Pipe made 100% of INCONEL From Z-Jet in ITALY.No RC pipe better anywhere in the World.Only thoughts on my mind where what a old set up the head was.Designed to be user friendly well before RC Jet Turbine parts became available I resided I would build the best 100 mm PJ ever.My first thought was just bolt a German ER100 head on with my 4 reed valve set up.I had to design the reed valves to work with a er90 backing plate.I had to silver solder the thread ring in also.Hubert sold me the parts I needed & got reeds High pressure Water cut in Perth ,WA.This took ages but when complete I went out testing static only .At first I though 100% success but soon realized two problems existed.Blow back out the front & erratic Thrust.Reeds where cracking up after 10 minutes & I could see heat was Very close to damaging them.I desided to try a different Conic Ring but that failed big time.The standard Conic ring it had was very good but held back thrust a tiny bit as return shock waves were trapped behind it.Many think this is OK as it helps burn up the fuel but to my I just had to recover some lost thrust.I desided to put a bigger valve backing plate in & use only two 10 thal reeds.The big reed has holes in it hovered only by the second small reed. As a vacuum arrives it opens the small reed first letting air into the central area.The bigger reed opens next as air speeds up.More air gets in & bigger reed gets air to cool its top side.The small reed hides behind the backing plate.Fuel gets sprayed 140 deg into reeds & backing plate to cool everything & backing plate reboils the fuel again.The only drama left was the fuel that washed onto the chamber walls would have to waight until the combustion heat reboiled it.This was half way down the pipe combustion chamber by then stuffing up thrust as did not burn first time round.The conic ring solves this as heat behind it boils the fuel on the inside.It comes at a cost of thrust as the vacuum wave gets trapped behind it to return latter as a pressure wave.I desided to try a new idea of my own never tried before .All I needed was a Center punch & a new 20mm conic ring. I made holes all around the conic ring but not drill holes .These holes look like a cheese grader .As air comes in it draws the Ex combustion heat forward behind the conic ring and into to incoming air .This made shore any unburnt fuel washing down was Cooked instantly ready to burn on every bang .I ran it on 20% diesel & 80 % Gasoline .The diesel protects the reeds & also the fuel pump seals.I use a Sacrificial Backing plate also as this absorbs the shock waves stopping chipped petals.Fired up it made 19lbs static thrust with afterburner.17 with out.Starts & runs perfect now .Reeds dont get hot at all.With afterburner the outlet flame looks like a Argus set up .The conic ring gets so hot now no fuel gets past unvapourised.And evan more important the Vacuum shock wave can pass through to draw more air in to get full thrust.Win Win you could say.With out the Conic ring reeds got so hot is only seconds they failed .Thrust only got to about 13lbs also.A test run with Nitro & methanol gong in at the front also only got to 14lbs .Lots of blow back out the front also.After the new bigger backing plate went in with my new conic ring all problem went away & thrust rocketed higher than ever.You can run it with no blower at all & it will not get to hot. As for the er90 I now use a two reed set up.It has run 40 minutes with a 3 reed set up before a reed snapped .Both 90 & 100mm are Awesome Pulse Jets & never have I got board with them.
My last test run of the 100mm Zanin had 16.lbs static then 18lbs with afterburner then 24.5 lbs with No2 gas added.This had a 4 reed valve set up.A two reed set up gets 1lbs extra but less running time.