Tuesday, April 7, 2009

Got my TRex 250 flying properly....finally!

Back in Feburary, I was having a lot of problems getting my TRex 250 to fly properly. I had lots of problems with tail wags, sluggish cyclic responses and getting the right pitch setup. Well, all that has changed, thanks to Bob Finless over in Helifreak.com for his setup videos on the TRex 250. I watched all his setup videos on the 250 and learnt a whole new bunch of stuff. I also found out what i was doing wrong and some new techniques on setting up the heli properly. I also changed a couple of things in my 250 to improve the performance and stability. Here are the list of changes i had made :

1) Tail Servo change
Change the tail servo from the stock Align 420 to the Hitec 5084 servo. The stock tail servo didn't seem to work properly and i would sometimes get a sudden lost in tail hold. Maybe it was dying. I read from the local forum that the Hitec 5084 was a good replacement so got my hand on one of those to try out. I guess i won't be going back to the stock servo anymore... :)

2) Tail linkage rod mod
The stock tail linkage rod was pretty thin and it would sometimes bend. This would have an undesireable effect on the tail and I decided to strengthen it by putting a metal rod into a hollow carbon rod. Now the rod stays rigid throughout.

3) Change the motor pinion
With the stock 15T pinion on the stock Align motor, i felt that i wasn't getting all that punch i needed, especially for 3D. So i change it to a 16T pinion instead and performance was better.

4) Crank up that throttle curve!
I am running a flat throttle curve 100-100-100 at idle1. Anything lower and i get sluggish performance. Flight times is abt 4 min with stock motor and 16T pinion. I am still contemplating if i should drop in a Scorpion motor... (hmmm....)

5) Ditch the stock ESC!
I got myself a Castle Creation Pheonix 25A ESC in replacement of the stock 15A ESC. The CC ESC are simply the best for heli. They have one of the most comprehensive software settings for heli and the firmware are constantly being upgraded! I love these and they don't run as hot as the Align stock ESC!

6) Watch that Gyro gain!
After watching Finless videos, I realise that my gyro gain was simply too high (i was at 60 - 65% previously) and they probably are the MAIN REASON why i was having so much trouble with my tail hold. I tune it down to 40 - 50% and immediately, the tail was holding great!

7) CF Blades
Last but not least, I got myself a pair of CF blades to replace my stock ones. And man, that made a difference. The flight is a lot less spongy and cyclic response also improves!

Those are the things i have change since my last blog in Feb. Well, at least now i am able to have a decent 4 mins of flight time (not hover) instead of 4 mins of 'struggling' time to keep the heli in control.

Time to setup my NIB Gaui200 SEV2 next! .... :p I will see how the 2 helis compare...

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