Something is wrong, here is a possibility:

Bad ECU settings(very high acceleration/ramping value), if this is the case, after you pass the 70K you'd have extremelly fast acceleration, you say you do, so this is a possibility, keep in mind that if this parameter is adjusted down you will also loose the fast acceleration on the high end of the RPM range. Popping is a symptom of un-vaporized(liquid) fuel being burned, this happens when fuel is being sent faster than the turbine can handle, just so you know, liquid fuel inside the running turbine is a bad thing.

Can you describe what happens to the temperature reading while on the 50k to 70k acceleration transition?

Just so you know, completely answering your question, other causes for slow/poor/uneven acceleration symptoms are:

- Bad bearings causing drag
- Bad combustion chamber with uneven burn
- Clogged or missaligned fuel needles not allowing proper fuel vaporization at the lower chamber pressure levels related to low RPM
This applies to ALL microturbines except the now dissappeared BMT's that had fuel injectors (they had no need to vaporize fuel as part of the turbine design)
- rubbing turbine wheel or compressor
- simply poor efficiency related to bad tolerances or improper assembly
- Rotating component mass itself limits acceleration velocity for a given turbine design, two turbines with same rotating components and their rotating components' mass being the same, but one with tighter tolerances than the other, the one with better tolerances will have faster acceleration (and will be more efficient than the other...).


The ECU verifies running parameters several times a second, fuel volume is increased, acceleration(RPM increase) is expected, if it does not happen, ECU waits before fuel flow continues to increase, this while watching temperature, this actually controls acceleration, the acceleration parameter controls how fast is the fuel flow is increased when the ECU decides it should. If the ECU parameters are set for faster acceleration than the turbine can physically obtain, the turbine actually bogs down, this is because fuel is flowing in faster than the combustion chamber can vaporize and burn fuel on the related chamber pressure, impeding RPM increase.

It does not make sense for a turbine to rely on ram air for acceleration, when you have the need for faster acceleration is when you actually have the less airspeed like when aborting a landing. Actually, many full scale turbine designs don't even have aerodynamic intakes that allow ram air pressure to build up.

All ambient factors (temperature, atmospheric pressure, humidity etc.) that impact air density do have an effect on turbine performance, but mostly on power output and acceleration speed, not on acceleration linearity, for example, on thin air you have less air for the compressor to bite, but you also have less air drag on the compressor, so it can rotate faster, those two cancel each other so everything else become equal, based on this, acceleration on less dense air could be faster, but it will also be more or less linear, same as in very dense air, based on your description, you do not have anything near linear acceleration on this turbine at this time.

SCJ can you explain how does the Evojet turbine measure airflow?