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250 Class Electric Helicopters 250 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.

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Old 09-01-2020, 11:22 PM   #1 (permalink)
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Join Date: Jun 2013
Default Trex 250 not enough power

Hi guys,

This heli model is old as hell and most of you have long forgotten what it is probably.

I have flown its DFC and SE (flybared version).
Currently fiddling the SE version.

I cannot get enough power out of it (any version with any motor/esc) and I don't mean ridiculous power, I can barely fly it safely - it does not have enough lift to recover from pitch drops comfortably, definitively cannot do any noticeable pitch pumps.

I am currently set it up with Phoenix 25A ESC, governed 3800/4200/4600.
Motor Scorpion 3900kv.
Batteries Turnigy Nanotech and Graphene 45-90C (probably overrated).
Servos are stock Align DS410(on pitch position there is SAVOX SH-0253, basically the same as DS410), movement is fine (Phoenix 25 gives only 5v voltage!)

On the 0deg pitch Normal mode I measured tacho ~3750rpm.
It seems to hold RPMs well (sound pitch), but I cannot say the RPMs in flight sound to be screaming high.

Pitch is around 11deg pos and neg.

Now the problem - in any flight mode if I try pitch pump - it is sluggish to lift up... well its subjective, but its terrible.

I have first started with plastic blades - just because they were there on this heli, now switched to some HK carbon blades (I do have also Align carbon, but they are not that much stiffer).

Has anyone an idea what could cause such a nice heli in such a monstrous power combination (motor+ESC) to perform like a soft sh*t ?
Most guys are looking for ways to tame it down, I cannot get it to enjoyable power in contrast.
Head dampeners are softer than I would like (new, but not hard).

I would love to measure its RPMs in flight but I doubt I could get it stable enough to check it with my laser tacho.

As I said - have flown its variations (curently own 3.5 of them ) different motors, different ESCs (throttle range calibrated of course).
I had 2-3 weeks ago on this bird stock Align RVC-BL250 motor with Pichler XQ-20 ESC. Strange ESC but it was flying close to acceptable, then suddenly it got in super weak mode - 80% throttle and it slightly lifts...), replaced to Phoenix/Scorpion setup - better, but still no good lift.
Feels like servos/batteries are not up to task but that's weird - batteries load well, hold charge, not kept charged too long, resistance around 6-7 ohm. I have some 9 of them, different.
Motor pin to main gear meshing is checked to be relaxed - not squeezed together.
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