250 Trex 250 Pro DFC Super Combo Completed

N

Nl Henderson

Member
Well I read somewhere that building a trex 250 was kinda of a pain. Amen on that. I finally got her done and did a maiden flight on the back patio tonight.

Man that wiring is horrendous!! I put the futaba receiver on the side and the 3GX in front of the tail servo like the manual called for. I have about 3mm clearance between the motor and wires along with a lot of zip ties.

But to be honest with you , I spent one night building it and two days setting it up. The 3GX kept rebooting on me when I was in ail limit settings. I finally got it. Kinda scared to get too high off the ground in case that thing wants to reboot on me. I had no trouble at all with the Trex 450 build (3GX:feedback:).

Anyone know if that one way bearing is supposed to be tight on the 250. It sure seams to be tighter than I would like it.

Anyway, here is a few pics of the progress.
 
Tony

Tony

Staff member
If that thing is rebooting on you, that is not a good thing. YOu may want to contact Align or an Align rep where you got it and have it replaced.
 
Lee

Lee

Well-Known Member
She looks so sweet. There is not a lot of space in her for gear is there? :D
 
N

Nl Henderson

Member
Hey Tony, I got the little Trex 250 Pro dialed in and she fly absolutely wonderful. It does seem to be a little underpowered though. Only gripe is, I have the collective set at 12 degrees and it just dont seem to have the power to handle that. Probably need to back it down to the recommended 11 degrees. I have to give a lot of collective to catch it (is this normal). The set up is spot on and hovers great. I am currently using the E-Flite 800mAh battery as that is all I could find here localy. I have (4) 850 mAh batteries coming in the mail, do you think this will make a differance in pwer (I doubt it). In comparing it to the Trex 450 Pro DFC, I can just bump the collective and she is heading up in a hurry.Oh yeah, the first couple of batteries I never got far off the ground (3GX rebooting on set up issue) since those 2, I have ran 2 more through it and no problems so far. Other than that, this little bird is wonderful. What should my pitch curve be set up for the 250. Here is what I have at now.

Norm - -30,-10,+10,+52,+100
IUP1 - -90,-50,+10,+50,+100
IUP2 - -100,-50,+10,+50,+100
 
Tony

Tony

Staff member
YEah the 250 will not compare to the 450 in power. Also, if you are using the plastic blades, they will make it feel a little sluggish. I would suggest the CF blades highly. As for the battery, it's negligible if you will get anything more flight time or power though. Doubt it.

As for pitch curves as well as throttle curves, the ones that I use are below.

Throttle Curves
Normal Mode
0 40 60 80 100
Idle Up 1
70 70 60 70 70
Idle Up 2
100 100 90 100 100
Pitch Curves
Normal Mode
46 48 50 75 100
Idle Up 1
0 25 50 75 100
Idle Up 2
0 25 50 75 100

<tbody>
</tbody>
 
N

Nl Henderson

Member
Tony said:
YEah the 250 will not compare to the 450 in power. Also, if you are using the plastic blades, they will make it feel a little sluggish. I would suggest the CF blades highly. As for the battery, it's negligible if you will get anything more flight time or power though. Doubt it.

As for pitch curves as well as throttle curves, the ones that I use are below.

Throttle Curves
Normal Mode
0 40 60 80 100
Idle Up 1
70 70 60 70 70
Idle Up 2
100 100 90 100 100
Pitch Curves
Normal Mode
46 48 50 75 100
Idle Up 1
0 25 50 75 100
Idle Up 2
0 25 50 75 100

<tbody>
</tbody>
Click to expand...

Two thumbs up on the throttle/pitch curves, I changed the throttle and pitch curves and they are a far better than what I had. Thanks again!

I am running the CF blades - I cant believe how impressive this little bird is. its rock solid.

On the second note: Does the one way need to be free like the 450? ( the 450 blades spin effortlessly on shut down).

The 250 seems a little bit tight. Is this ok or should I take the shim out? As soon as I spool it down the blades stop rather fast and do have a little resistance.
 
Tony

Tony

Staff member
Really on a 250, the one way should just be a straight gear like the mcpx. Since the tail is driven off of hte main gear, and not an auto rotation gear, once you kill the power, you kill the tail as well. This bird is meant to have power to it all the time. I would just leave it as is (unless it's binding pretty badly) and let it wear in over about 10 flights and see where it is then. If it's still tight, see about removing the shim. However, you do not want any up and down play with the main shaft so you may have to take your main bearing blocks and loosen the bolts and either squeeze them together with the shim in place (what I would do!) or pull them apart without the shim.
 
Lee

Lee

Well-Known Member
How is the gear mesh fro main to pinion? If its too tight that could be stopping it abruptly. You should have the tinyiest bit of free play between the main gear and the pinion.
 
N

Nl Henderson

Member
Mesh is good, Im thinking now everything is fine, since I got my pitch curves set up right. Thanks for the help.

I see you have the ikon brain, I want to put thiamin Goblin 500, Witt the bail out option, what do you think?
 
Lee

Lee

Well-Known Member
That would be awesome for the Goblin. I'm thinking to get another for my 600
 
N

Nl Henderson

Member
Have you tried the self bail out feature, I've only seen a video on you tube but it was short? What size heli do you have the ikon on ?
 
X

xokia

Active Member
I've been thinking about one of these 250's and I have a question. I keep seeing people put RX connected to the 3GX even when they have a DX8. Is there a reason people are using the RX over just using the 3GX and sattelite RX?
 
murankar

murankar

Staff member
With Specktrum folks may already have the rx and not the two satellite rx's. This makes for a cheaper install.
 
Tony

Tony

Staff member
there are posts out there that the 3GX is ONLY 22ms and if you run the AR8000 you can run at 11ms. I have not read or heard anything that would be considered proof of this, but that is what they say. I run the dual satellite Rx's on mine myself.
 
X

xokia

Active Member
I have been contemplating getting one of these 250 pro dfc helicopters. I think the performance of the blade 300x kinda sucks. The one benefit though is parts for it are just as cheap as the mcpx. What's the part repair cost on these 250's?

And what's the common part/parts that break during a crash?
 
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