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RC turbine engine failing to start on the B3 helicopter

Posted: Thu Jun 20, 2019 11:10 pm
by Mdrashy
Am working on a project where we use RC turbine engine mounted on a carbon profile to achieve the dream of flight. We use As 350 B3 helicopter for the operation where we go 4500 feet and then starting then starting the turbine engine. There is a guy attached with the wing mounted with turbine on either right or left side of the helicopter (we remove both side doors so that we can have the guy resting on the foot rest of the heli with a wing on his back also no seats on the heli). Coming to the issue when we start the the wing (jetwing) at 4500 feet of the wing is on the right side the RC turbine engines start easily but on the left side it always fails to start always low rpm fail for start up and then after two three try it starts. Any idea what could be the issue here. Is it rotor wash or something else. Please note that the turbine attached on the jetwing when the guy is on the skid is turbine inlet Is perpendicular to the rotor blade.

Re: RC turbine engine failing to start on the B3 helicopter

Posted: Fri Jun 21, 2019 5:32 pm
by stephanwintner
I am struggling to understand what you wrote. I think you are saying you have a small RC turbine mounted on a test rig underneath a helo rotor, sticking out of the open door, and pointed up (turbine inlet faces up). (I guess a university project?)

On one side, the turbine starts easily, on the other it tends to get a hung start but after several tries it does start?

I would suggest looking at the direction of rotation of the helo rotor and the turbine blades. I suspect you are getting an interaction between the rotor wash and the turbine, which causes a hung start, unless the turbine is already been warmed up by the prior hung starts.

It seems to me that whichever side you are on, the rotor wash swirl would increase or decrease incidence at the front of the turbine's 1 compressor stage (1 shaft I assume). But that should be the same on both sides of the helo. However, the fuselage shape, and helo engine inlet and exhaust are in a different spot relative to the rc turbine inlet.

How far outside of the helo does your rig extend ? You may also want to try flying the helo forward or backward while trying to start, that would alter the rotor wash pattern.

Any gas turbine aero guys here?

Re: RC turbine engine failing to start on the B3 helicopter

Posted: Fri Jun 21, 2019 7:49 pm
by DH106
As an RC turbine flier, low RPM failure to start smacks of bad turbine battery.