Hi,
We fired up the ProTech PT80 turbine yesterday. The turbine works but not as we have expected:
The engine fires up and quickly accelerates to ~38,000 RPM. While it heats up, the RPM drops to 32000 and remains at that point. Then we sometimes gain control over the turbine and max RPM is ~70,000 (compard with expected 116,000) and acceleration is very poor at 20 seconds (compared with the expected 4-8 seconds). Some other times, we do not gain control and need to disconnect/reconnect GCU or even shut down and re-start the turbine.
ECU/GCU is ProJet.
Either we don't get enough fuel into the engine of the ECU is holding the power back for some reason. What pressure would the fuel pump produce in this range of turbines? ours just spills out some fuel but builds no real pressure.
Thanks for any input.
Nir

Nir,

You have to calibrate the pump so that it will work per specs. Look in the Projet ECU manual on how to calibrate it. It usually takes about two minutes for the whole process, then everything will be alright. A friend of mine had the same problem with his Behotec 130 and he solved it this way.

Regards,
Chris

Thanks Chris,
As you can see, we finally got the PT-80. It took some time to get it to work (propane solenoid would not open up under the pressure from the propane tank so we had to fiddle with the valve on the tank to not overpressure the solenoid. Once we did that, it fired up right away.
I think we went through the pump calibration process but it is a good suggestion to re-do it. How much pressure should the pump produce? The pump voltage range in the ECU is only up to 2V and this produces very restricted fuel flow (with the pump disconnected from the fuel valve). I think that under the back pressure of the valve and the fuel jet, the fuel supply drops significantly.
I will go over the system again today. Maybe I will have some clue.
Do you have some suggested settings (even if they are for another turbine) for the ProJet ECU? Just for the sake of a sanity check..
One more thing - if battery voltage drops, can it be that the ECU restricts the turbine max RPM? How many cells do you suggest (we currently use 7 cell 2400mAh pack).
Thanks,
Nir

Hi Nir,

My friend uses a seven cell battery too. I don't think that 2 volts will push enough juice through the pump to make your engine run properly.

Make sure the battery pack is freshly charged and that you have at least 8.6 volts available for a good strart.

I'll ask my friend to pass on his settings to me for reference.

Are located in T.A.? Temps must be as high as here in Nicosia this time of the year.

Good luck,
Chris

Yup, I am located 20km from Tel Aviv. Temps are high (~30 degrees celsius) but Iv'e seen worse and I think in Europe they have seen much higher temps in the last few weeks. Anyway, everything is airconditioned. You only get a feeling of what is going on outside when you go flying...
I'll be looking forward for the settings. We couldn't get the pump voltage above 2.0V (I don't know if it is the actual voltage or just a number).
Nir

If you are putting a volt meter across the leads going to the pump, most likely your are not getting a meaningful number. Power to the motor is controlled by switching the power on and off at a high rate, but at a constant voltage. It is the on time compared to the off time that determines the amount of power the pump produces.

You might check to see if there are any fuel restrictions in the system (kinked lines, plugged filter and so on), I am not familuar with your set up, but I have seen other engine display this type of problem, and it allways was a fuel restriction.

Steven

Thanks steven.
I know that power to the pump is PWM modulated. I quoted the numbers from the ECU (2.0V for the pump). I would not go as far as putting a DVM across the leads unless it is a true RMS meter that would average the pulses and give a meaningful number.
What I will do next time I am at the setup is check the pump by directly connecting it to the batteries, bypassing the ECU.
Nir

Fault was traced to the Kerosane solenoid. The solenoid sticks under heavy pressure from the pump, thus shutting down the turbine when it accelerates.
We replaced the valve (luckily we have two kits :-)) and WOW. 117,000 RPMs of noise heat and thrust. We had to call it a day at 10:30pm in fear of the neighbours. We set acceleration in the ECU to 6.0 seconds and in practice it was about 8 seconds idle-full RPM but we have a couple of parameters we need to go through before we actually get the engine in tune.
Now all we need to do is mount the engine and go fly.
Nir

Hi Nir
do you still have your PT80?, I have one and although I have has plenty of success with it about 2 and a half hours run time I am having trouble with it. It starts well a little flaming but nothing to worry about throttle up and take off is fine, if I run at full throttle for the entire flight (6 mins) all is fine although if I throttle back in flight it will not accelerate back up I just get a flame out the back and loss of all power the same happens on the ground. It is mounted to a supper reaper I have changed both the gas and fuel valves and the fuel pump with jet cat parts but with no effect. Any ideas?

Do you know if the injectors are replaceable as it does look like the problem beguines from the same point in the combustion chamber each time as if one of the injectors is over fueling perhaps?

Try and increase the acceleration time and try again. As you said, it sounds like overfueling. If it does not solve you problem, it could then be fuel nozzles which will require factory repair.

Zane

Thanks for that I have tried taking the acceleration ramp up tp 8 seconds way below expected performance but the same problem when it gets to about 75-80K RPM. I think your diagnosis is correct I am trying to contact Protech now with the intention on sending it back for factory repair, Thanks again Zaney1
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