Starting engine with high pressure air!!

[Jetman]

Hello all! I am wondering how exactly these diy engines are started with high compressed gasses?? Had an accident with my fingers starting with a high pressure vacuum and am looking for an alternate means of starting… Thanks

[racket]

scuba tank impinging onto the compressor wheel near the exducer

[Jetman]

Is there anyone that has plans or pictures of this willing to share??

[racket]

ibb.co/F8BB69Q you can see the fitting on the front cover that feeds the scuba tank air at a tangent to the wheel

[Jetman]

What would the best way to mount it on and what nozzle for the co2?? Thanks

[racket]

Its easiest to come from the "inside", workout where the comp exducer radius would be situated , then mark a position at a slightly smaller radius and drill at a tangent to the wheel , its going to be a fiddly job on a scroll housing.

An alternative is impinge on the turbine wheel , much easier job

[Jetman]

For impingement on the turbine wheel, would the gas be pointed tangent still??

[racket]

Depends where you mount it , but yes , it needs to impart as much energy to the wheel as possible so a tangential impact is best , but it can be in the same plane as the wheel rather than from the side as it would with the comp .

It can as simple as drilling a hole in the outer edge of the turb scroll and braze in a bit of metal tube

[Jetman]

Should the metal tube stick into the turbine scroll and if so would this effect flow?? What size of pipe would be adequate??.. sorry for all these pestering questions 😅

[racket]

You only need 1/4"- 5/16"OD stainless tube , and preferably not sticking very far into the gas flow area in case it breaks off and goes through the turbine wheel , maybe 2 diameters of length inside , it won't affect flow to any degree .

If using steel tube , don't have it projecting inside as it'll burn off

[Johansson]

I used turbine wheel impingement on my JU-01 and JU-02 engines, worked like a charm. If you plan to use CO2 I think it is better to inject it downstream the combustor since it might mess up the flame if used on the compressor side.

[Jetman]

Ok, sounds good 👍

[Jetman]

Does this placement look good?? 

[racket]

yep , its getting near the end of the scroll so closer to the wheel for best energy transfer , just make sure the tube orientates a bit in from the tangent , maybe stick a short length of tubing into the hole and look through the bore to make sure the start fluid will impact the wheel, not too close to the inducer tip , maybe a half inch down the blade .

[rocketman_mike]

Mine has turbine impingement. It works, but Im thinking it consumes way more air than if it were on the compressor side. I dont think I have any photos of it, but mine's just a 1/4" stainless hose going into a 1/8" fitting that's been threaded into a hole drilled in the turbine housing. Makes for a cool sounding start up.
www.youtube.com/watch?v=pn4k-LLZAn0