250 heli build help - copterx 250

[bazsound]

Got the belt replacd today and gave it a test hover in the ouse.

Sounds really smooth now. didnt use the vibe monitor but just sounded way better and was also holding fine.

Theres still wobble on aileron sharp inputs but elevator is fine. probably the swash plate. I have a plan to preload the swash to eliminate the slop. seen a few people do it with a spring.

[bazsound]

tested outside, its worse. any wind at it starts wobbling pretty bad. felt realkly unstable and just unflyable.

ill be putting the stock dampers back in.

And lynx have marked my ticket as resolved but never gave a reply.

[gimbleguy]

lynx has abandoned the 250, since their own release of oxy.

[bazsound]

I was considering an oxy3. not if thats there level of customer support

[bazsound]

Well, i solved the issue.

Put the stock dampers back on and hay presto. It even sounds quieter.

seems to be the lynx dampers wont work without an absolutly perfect 250.

I'll be replacing the swashplate with a tarot 250 swash plate soon as the dfc swash is pretty sloppy and that might be the issue so i may put them back on since its only a 5 minute job swapping them over.

Anyway im out to fly my 250 since theres no wind, and also get some more testing on the 450 which i just fitted a new gear in the front TT.

[gimbleguy]

The 250 DFC just doesn't like hard dampers, the 450 DFC can take soft and hard dampers.

Anyways glad you sorted it out.

[bazsound]

Originally Posted by gimbleguy

The 250 DFC just doesn't like hard dampers, the 450 DFC can take soft and hard dampers.

Anyways glad you sorted it out.

i dont understand why they are still being sold, and how some people got them to work.....

anyway

trex 250 flying (4 min 15 sec)

thanks to 2 weeks of not flying my 250 my flips are so damn rusty

[gimbleguy]

very nice, that doesn't look like a copterX any more.

[bazsound]

Originally Posted by gimbleguy

very nice, that doesn't look like a copterX any more.

frame, esc and motor. thats about it rest is align. even the skids are align

[bazsound]

So it loosk like something is definatly not quite right with my 250.

after gettig the 450 up and running for 3d, its evident that the 250 does not flip flat at all. the 450 is as flat as a pancake. flips are effortless.

the 250 takes more effort as you need to feed in aileron to flatten it out..

time to look at replacing the swash, its a bit slopy im probably getting a little cyclic interactionn

[bazsound]

Damn this 250!!!!!!

tail is all over the place, wagging in the wind. increasing gain made it more locked but then once i started pushing the tail and doing stall turns it went int WOD (trigger finger on flight mode switch for save)

reducing the gain made it loose....


i perceviered and just flew not letting it stop me fly... the previous day i almost had a crash because i thought the tail let go.


It wasnt the tail, it was cyclic. during a roll something weird happened, well i worked out its like ive give back cyclic half way through the roll. It only happens with quick rolls. if you do a slow roll its fine.

i guess i should try replacing the swashplate...

[navigator2011]

Yep, the 250s seem to be very oscillation prone, to say the least. I've had WOD in both the cyclic and tail areas. The tail one can be violent--after it started, the only thing I could do to stop it was put down 250 down fast! I love the size of the 250, but all the oddities have rather dampened my enthusiasm.

[bazsound]

yup nothing like the 450 which despite being 2nd hand has been solid with very few pieces replaced. even though it has a vibration problem it flips and rolls true and straight. tail never even hints at a wag.

the 250 ........ ok im not bothered with a little wag here and there but recently god!!!!! just blow on the tail and it has a fit.

and copmbine that with the weird cyclic interations on rolls........

where do i start. i just did the double bearing mod on the tail.

do i get a new align swahs and have it go sloppy in 5 flights or should i just go tarot and wait 3 weeks for half the price but be a non dfc swsash and risk a link popping off

[gimbleguy]

yeah the 250 is very finicky, some say if you can make a 250 fly well, you can fly any heli with ease.

Make sure everything is mechanically good.

[bazsound]

Originally Posted by gimbleguy

yeah the 250 is very finicky, some say if you can make a 250 fly well, you can fly any heli with ease.

Make sure everything is mechanically good.

The only thing that sticks out really is the swash is a bit sloppy but i cant see that causing a sudden elevator interaction during fast rolls.

[bazsound]

Well the 250 is flying again. Not sure what fixed it as i did multiple things

remounted BAR board (its decased) with different mounting tape and hotglued corneres to stop it moving.

Retensionsed belt (it was a tad loose but it wasnt skipping in flight)

Put a small washer in the tail box to remove play form the tailshaft, the washer is slightly too big so its causing binding on the bearing.... noticed the drag in flight its not too much of a hit in performance bt i think im just going to remove it as i dont think it really makes much of a difference to the tail. I can feel the resistance when turning the mains.

Heli though no longer piros flat.... which is annoying as i was wanting to try half piro flips....Everything else was fline, FF FFF stall turns. half flips, full flips. just piros wobble a little.

[ame="https://youtu.be/bBO3lKzR0yg"]Trex 250 Mild 3d practice - YouTube[/ame]

[bazsound]

I think ive decided against saving weight on my 250, the only place im willing to do that is the servos , it would reduce the weight to probably 320g, but after getting used to windier conditions and having it handle fine 15-20mph id rather have a little bit of fat to handle the wind than to be beaten by wind which is commen where i am.

AFter hte last practice session where i was starting to get tic tocs (thought they wernt possible due to the weight nope just my poor technique) i now no its possible on my heli even in the wind with some practice. So im going to change the pinion from 15t to 16t for higher headspeed :-) just need to find somewhere that stocks the scorpian pinion pack in the UK!!!

[bazsound]

i made a change to my pitch curve as i was getting annoyed with the mushy collective and having to use alot of stick travel. 20% negitive on the devo and wow what a difference.

instantly made tic tocs easier to practice. and flips are so much easier tooo, bogging much less aswell as i guess im catching the heli earlier before it starts to drop.

still have an annoying thing happening during rols to inverted which look like the tail is dropping. ie giving up elevator

[Krager]

Originally Posted by bazsound

i made a change to my pitch curve as i was getting annoyed with the mushy collective and having to use alot of stick travel. 20% negitive on the devo and wow what a difference.

I've been using 12-13 degrees with a linear curve on all my helis. I'm running 4600 rpm head speed governed on my 250. It did feel mushy until I put a higher Kv motor in it and upped the head speed. At 3800 rpm head speed it felt pathetic, like it couldn't get out of it's own way. Getting the weight down also made a big difference. I'd run 5k head speed if I could, but then I'd have to increase Kv on the motor again and it would really load the hell out of the battery. I could go 4S, but the battery compartment on the T-Rex 250 is really tight, big complaint I have about it.

[bazsound]

Originally Posted by CraigHB

I've been using 12-13 degrees with a linear curve on all my helis. I'm running 4600 rpm head speed governed on my 250. It did feel mushy until I put a higher Kv motor in it and upped the head speed. At 3800 rpm head speed it felt pathetic, like it couldn't get out of it's own way. Getting the weight down also made a big difference. I'd run 5k head speed if I could, but then I'd have increase Kv on the motor again.

im quite happy with the way it is just now that ive changed the pitch curve... bearing in mind i have built in expo built in as i went in 1 hole on the servos to help get the numbers up in vstabi. If i had the links so they were parallel with the frame my numbers were a bit low.

ofcoarse thats probably fine but i trimmed my servo horns so cantr really change it.

i still get 5 minutes even though im hammering it now, and batteries come down at 11v-11.3v

jsut need to find this weird elevator trhing during rolls.


really want to save some weight but i just cant justify spending £50 on servos when the ones i have while being a tad heavy work perfectly fine. i can aleawsy fly without the canopy