1. whatever works as long as wires aren't exposed to moving parts. Where a wire has to cross the edge of a piece of carbon, either sand the edge of the carbon and/ or protect the wire. Braid, silicon tube, heat shrink, all work for that.

2. http://www.rcheliaddict.co.uk/align-...3gx-setup.html

3. as it is supposed to be able to use a quite hard mounting according to specs I would say 1.

4. velcro, cable ties?

5. No. Find it out by experience, asking, and above all Google

Ok, thanks for the comments.

1. Having already done a 450 Sport, I get all of that. I was rather hoping I might get some feedback from people who have actually built the 250 DFC as to what worked well for them. Did they put the ESC in the recommended place, and if so, where did they route the wires, did they do something different, and so on. In general it looks like where wire crosses carbon Align have already added plastic edging to protect on this particular model so that's great. Saves me a job.

2. That link will come in handy later, ta. It has no info on mounting the 3GX in the 250 DFC though so I'll run with the pins facing forwards, not sure it can go any other way. I think I'll try and sit it just a couple mm away fom the servo mount too in case that interferes.

4. Of course, overlooking the obvious

5. Smiley didn't come out!

In truth, of the people that frequent the T-Rex 250 sub forum, it doesn't look like hardly any have actually built one of these yet. I guess that's understandable as they've really not been out long!

The other questions are answered so I'l just add my 0.02p

here are a few pitures of my wiring...

I had to put the esc on the side due to using a futaba compatible rx and not sat cables for spektrum.

make sure you keep the wires away from the motor if you do this route.

Also be doubly sure there is absolutely no binding on the tail even at the extremities of movement. I got a wag that no amount of gain reduction could shift and found a tiny dollop of loctite on a collar on the tail mechanism.
Cheers
Steve

trex250canopyonlhs.jpgtrex250canopyonrhs.jpgtrex250LHS.jpgTrex250RHS.jpgTrex250under.jpg

That's really cleanly done!

I had a chance to take mine up the field yesterday and I have to say, I LOVE IT!!

I had turned the roll rate right down in the 3GX as the first hover flight indoors I thought was mega twitchy and sadly I've turned it way too far down as it was really wallowy, but even like that I was almost on to circuits on just my 2nd flight. Sadly I don't have a laptop so its a case of try it, take it home, tweak it and then wait until the next suitable day to test. (I forgot the manual so couldn't do it manually!)

I do have a bit of a problem with the build though and may need to redo it, which is really annoying. I noticed quite a few of my frame screws arent tight. I know what the problem is, when I was doing them up I thought I was going into metal. Turns out it was plastic and I over tightened. Not sure what to do about that yet. It's the bearing block holders mostly I think.

Guess I'll have to investigate different screws and / or new bearing blocks, maybe some ally ones or something. Annoying but only myself to blame!

Also the orange RX satellites that I'm using are shite. On range test I only get to about 10m. On full power I get plenty far enough away for it to not be a problem but I need to be aware of it and swap them out before I start getting too confident and flying much more than test circuits. I'll cuss if I get a brownout

As long as you don't go mad with it you may get away with using ca glue on the twisted through threads. Remember even screwing into metal on these sizes of heli on require a finger and thumb grip rather than holding in your fist. I reckon that is why align give you that pathetic little screwdriver it is so small it is hard to hang off it when you are doing stuff up.

You will be able to test for the shut down issues on the bench.

Disconnect your motor or use throttle hold as long as it is set up properly...
Hold on full diagonal cyclic for a couple of seconds if the servos keep pushing until you get a reset you need to have a think about if the ESC/BEC circuit is man enough. I am using a 5a external BEC now as I dont like watching my Helis doing pheasant impressions...

I had previously figured I'd never be holding on a control command for a few seconds but when I was tuning the gain on the tail I had it a little too high and fast forward flight gave me a real fast wag and it fell out of the sky.. Didn't do much damage but enough to stop me flying this weekend...

Video of the cutout on the bench.
http://www.youtube.com/watch?v=a3Hry...e_gdata_player

Have fun.
/Steve

Yeah, my bad on the screws. I know not to much more than just nip them up with some thread lock on metal and to barely even do that on plastic, but I honestly thought I was screwing in to metal when in fact it was plastic. I got muddled! Doh!

I guess I can try a little CA. At the end of the day, the alternative is to replace the bearing blocks and screws anyway so I may as well see if they'll nip up with a bit of CA. If they do then I can at least put off replacing the bearing blocks until I crash and break something. Which with the confidence I feel in this bird, I'm sure won't take that long

What shut down issues by the way? Was that from another thread?

Sorry yes, the shutdowns seem to happen as a result of overcurrent protection on the ESC, the result is the 3gx resets in flight, as the power for the 3gx comes from the esc and then feeds the rx you lose everything.

there are a few threads about it on helifreak. if when you are test hovering it just plops down and the 3gx re initialises then you have just witnessed it. it happened to me a few times when dialling in the gains on all the axis. but as I was in a hover about a foot off the ground it just landed. I thought by setting swash ring in my TX I would have limited the amount the servos can move, but obviously a fast wag can set it off too. as I found out. if you have a watt meter then it will be worth running it through that just to make sure you dont have a chance of it happening.

I emailed align to see what they had to say about it and one of their guys mailed back saying make sure I have the travel limit set to 40% for a 250. (I think I have but I'll double check later)

it flies a lot nicer than I expected it to, much bigger than it is. to me it feels like a flybarred 450. I love the little thing I just hope that adding the external bec will sort out the esc issues.

/Steve

Ah, ok. Definately check that setting. I read about the ESC overheating and one way I read to test it was to continually stir the cyclic to its extremes for a couple of minutes and that if it was going to cut out, it would doing that. Mine didn't and I have got the travel set to 40% in 3GX so I'm hoping it's ok.

Mine does seem very sensitive to changes in the throttle stick. It will change height quite readily in hover but I was going to look at my pitch curves again to see if they're ok. I found the instructions to be very contradictory. In the 3GX setup It clearly states +/-12 degrees pitch, and then in the rest of the manual it gives entirely different figures so I set it up in the 3GX with +/-12 and used a pitch gauge when setting my curves in the TX to achieve the pitches for low, mid, high etc. that they'd specified. It ended up being some very oddball pitch curves!

Not sure if that is right or wrong but my guess is that my pitch change is too violent around mid stick causing it to drop too easily...

Hope that made sense!

post up your curves. I won't be much help but I am sure if I give any rubbish advice someone will point it out!

I tend to leave the top half of the curves alone, and just trim the bottom bit for normal mode, everything else is a diagonal line.

so

for pitch
idle1 and 2
0-25-50-75-100

normal
30-45-50-75-100 or something similar to that. aiming for about minus 5or6 degrees on full negative.

throttle.

normal.
0-60-75-85-100 (IIRC)

Idle1

100-85-85-85-100

idle 2

100-95-95-95-100

tail gain about 30% in idle 1 and I was in the process of tuning normal when I got a fast wag in FFF and it died and crashed. probably end up at about 33% or so.

hth
Steve

OK, I'll post them up tonight. Cheers!

(they're nothing like that though )

OK, throttle first as they're easiest...

Nrm: 0, 40, 70, 85, 100
UI1: 80, 75, 70, 75, 100
UI2: 100, 93, 85, 93, 100
H: 0, 0, 0, 0, 0

Pitch curve...
Nrm: 45, 55, 65, 78, 92
IU1: 2, 34, 67, 80, 92
IU2: 3, 26, 48, 74, 97
H: 50, 50, 50, 50, 50

Now, like I say, the reason the pitch curves are a bit 'oddball' is that I set it up mechanically for +/-12 collective as per the Flybarless setup instructions. (I also set cyclic to +/-8, but that won't effect what we're talking about here). Then, once I'd done the flybarless setup I went back to the pitch and throttle setting page in the book and used the pitch guage to give what they said, so for general flight +11 at 100% throttle, +4 - +5 at mid stick, -2 - 0 at 0 stick, which was the 45, 65, 92 and I then just filled in the middle numbers (points 2 & 4) to make the curve as smooth as possible.

Confused??!!

I may be totally off the mark on what I've done but that was the most sense I could make of what I was reading.

Ok.

I can live with the throttle curves I'd probably up the 40 in normal mode so you don't drop too much head speed on final approach if you need a little negative pitch to get it in. I'd be inclined to up that to 70.

The pitch curves are ok if that is what you want to get. Most people set the max pitch in the ccpm percentage so at least one of the curves have 100 percent travel.

Hold should be a linear like idle 2 or maybe the same as normal mode at least you may be able to auto it down. Or are you using it as a bail out to neutralise the inputs and minimise any damage as the 250 doesn't really auto?

Unless you fly scale you may want to try to have 0 degrees at centre stick then you have easier translations into inverted stuff. Hover is usually just under 3/4 stick for me. There is nothing wrong with what you have set up but if you are planning 3d style flying one day then you may as well make the transition as easy as possible.

So in summary, set zero to centre stick ( this is what I'd assumed you had hold set up for)
Set the ccpm pitch percentage to give 11 degrees or 12 or 10 (whatever you want as max pitch in maniac mode) then work back from that keeping the top half of the curves pretty much the same as each other.

Remember the throttle curve will keep the motor from bogging at the top end of the stick movement.
And the model won't jump around as you change flight modes. Ideally you want the same sort of pitch setting as you flick modes unless you go straight into iu from hold. With what you have if you are hovering at 5 feet and flick into idle 2 it looks like the heli may drop a little as you switch?
Keeping the same top ends helps stop that happening.

Sorry for waffling on and I hope I'm not trying to tell you to suck eggs...

Cheers
Steve

No problem! I'll read through the rest in a min, but just remembered why that throttle hold 0,0,0,0,0 is there - to make life 1000% easier when setting up mechanically for 90 degree servo arms etc.

It's for no other reason than that so I've obviously forgotten to set it to something else. Oops!

Throttle hold 0-0-0-0-0 needs to be there! That stops the throttle stick working while you are carrying the bird around or when you are about to crash ;-) the 50-50-50-50 is the one to edit...

/Steve