Putting my merlin 160, into a a.d rafale how close does the turbine need to be to the jet pipe, The jet pipe is a 2 into 1 if that makes a differents.
thanks for any help.

25-30mm to the main tube should be about right.

Dave Wilshere

Dave, Are you talking about a 25-30 mm gap or tailcone inside the pipe by 25/30mm?? I'v wondered this myself on a few.

On a single cone turbine (Merlin, P120 and P160 etc, Booster) the distance between the back edge of the turbine tail cone to the start of the tube (not bellmouth if large spinning) actual tail pipe tube, which on a 160 is usually 80-85mm 3 1/4-3 1/2" dia section. Gap not inside

If the tail pipe has one of the small flared lip then measure to that 25mm gap.

Dave W

Hi

That is what I've been told from a couple of years ago, when I entered turbines. Nevertheless it seems that rules have changed for quero starts, because I see people and recomendations to put the turbine rear cone inside the pipe, because querostart throws a bit of flames......

Is this right?

Regards

Nuno

the pipe spacing is different for different engine manufacturers, example, what works great for a JetCat is too close for a Jet Central. it makes no difference if it's propane or kero start.

If the Kerostart turbine spits fire during the start, reduce the pump start voltage! The distance depends on the tube diameter verses the tailpipe dia as cool air needs to pass around and through the tube. As a general rule, as I said 25-30mm is a safe distance with the temperatures as a concern.
Obviously if the starter slips, the ECU battery is weak or the pump starting voltage is too high the turbine will spit flame, as long as it is being blown down the tube and not getting the tube blue I'm happy enough.
Open duct setups suck in my mind, some get away with it by using a cover/deflector. Minimum need is a decent front cone

Dw

This is the setup of my Merlin 160 in a Jet Legend f-22.

The distance between the end of the Merlin cone and the front lip of the bell mouth is 20mm or around 0.75".

I suppose there needs to be gap ?

I have read about some setups where the turbine cone is inside the tailpipe and I am unsure if this is only if a bell mouth is not used.