BEHOTEC J66HP RPM issue

[marko1]

Dear JET modellers,

I have a problem with my older BEHOTEC j66HP engine.
The engine runs great, the only problem I have is that about 2-3 minutes into the flight the engine cuts itself down to ~66000rpm thus reducing thrust, which is bad felling from a safety point of view.
After landing the engine does not stall but runs at ~66000rpm even with the throttle fully open.
After stopping and restarting the engine, the engine normally ramps up to ~121000 rpm and the effect repeats itself after 2-3 minutes.
Please any idea where the problem could be.

- no bad flow in line is observed
- the battery is always fully charged
- there are no visible vibrations, no defect is visible on the floor when the engine is started
- engine start like a dream - gas start

BR Marko Frank

 

[Segler89]

Hi,

Can you tell us which version of the Projet ECU you are using? With the given information I would assume that the software enables its failsafe (lower rpm output instead of complete engine shutdown).

Could be an issue with the pump or any of the sensors. It might also be a heat problem. Did you check the engine temperature or the max values on the GSU respectively?

Cheers

 

[marko1]

Hi,

I am using ProJet hornet ECU I believe it is one of the firs ones, unfortuantley I can not read version today, will check it.
At max rpms I read 2.1V on EDT and temperatures was in normal range a little bit over 600°.
Full pump its older one standard blue colerd aluminium housing, I so-pose its orbit one.
Will try to reset and try again.
It is bother me that engine fire it up perfect, run 2-3 min perfect, that suddenly drop rpms.

BR Marko Frank

 

[marko1]

Hi,

In meantime I mange to change pump from my JETCAT P60 SE turbine and done some flight test. Original one has leakage at rear end.
First flight went OK, second flight rpm issue repeat.
ECU: HORNET V4 J66HP OPTIC V5.2
Temperature of turbine at ~72000rpm 560°C.

Some more ideas please?

BR Marko Frank