RX2702V setting for T-rex 450 pro FBL - RC Groups
Thread Tools
Mar 31, 2011, 09:37 AM
Registered User

RX2702V setting for T-rex 450 pro FBL

OK, I just installed a walkera RX2702V 3 axis gyro on my t-rex 450 pro, and here is the setting I came with to make it flyable close to a flybared one, but more agile, if it can help anyone who want to try that 3 axis unit on a rex 450, here we go;

This is for the T-rex 450 pro or any other clone of the ''pro'' model, as for the SE, V2 model, the setting will be different, but close.

The flybarless Rotor head I use is the Align 3G one, if using a different head, the setting will be different since the resolution can be different.

For the pro model, the Elevator servo must me mounted on the left side frame (looking at the heli tail in).

The next servo located at the front/left must be connected on the Aileron port, and finally the last one, (front right), on PIT port.

The unit must be mounted upside up and the connection lead facing front.

Ball link distance on the servo arm must be at 13mm or very close to that.

I use Spektrum H3000 Digital servo, if you use different servo, you will probably need to reverse it in a different way in the REVERS menu since some servo are reversed motion.

SWASH: must be set to 3 SERVOS 120°.

REVERS: AIL, ELEV set at Normal, and PIT Reversed.

TRVADJ: AIL, ELEV & PIT set to 115% in both direction *** very important***

PITCHcurve: all set to 0%, 25%, 50%, 75%, 100% for now.

Now you have to level your swashplate and manage to get 0° pitch at midstick.

Once the mechanical part is done, you can enter the set-up in the 3 axis unit, press & hold the set button till the red led start to flash, then release the set button.

Go to SWAATS/SWASHMIX menu in your TX, set ELEV +100%, AILE to -100% and PIT to +40%, ensure you with a pitch gauge that PIT at 40% will give around -12/+12 collective pitch.

Move the throttle stick at mid position (0° pitch) then press and release the set button, now the ELEV led will flash, move the cyclic stick full forward, keep it there & press again on the set button, release the button and release the stick.

The AILE led should flash now, if yes, then move the cyclic stick full right, keep it there & press the set button, release the set button, at this stage, the swashplate will move up & down, the set-up is done.

In the SWAATS/SWASHMIX menu you must lower ELEV to +40%, AILE to -40% leave PIT also to 40%, then exit that menu.

If you measure the cyclic pitch you will see that WOW..!! both ELEV & AIL give a big +15°/-15° of cyclic pitch and/or does not keep level movement, but don't worry about that, this is normal on the ground, once your helicopter will be in the air, the gyro will sense roll & pitch movement and the cyclic will be around +9°/-9° at full cyclic stick, the roll & pitch rate will be a little faster than a flybarred T-rex 450 at +9/-9° with these setting, but not much, I can comfirm you at 100% since I have both, if you want it faster, you can up AIL & ELEV swashmix to 45% 50% but this is very close to the max setting you can get at 50%.

Before to fly, double, triple check the swashplate move in all the correct direction.

I strongly recommend you to start with 25% EXPO on both ELEV & AIL to familiarize you with the behavior, even higher if it's your first collective pitch heli, actually mine is at around 15% and it's fast enough for me around center cyclic stick.

If you want it smoother at full cyclic stick, you can put the dual rate at 80%.

Don't forget to set your Normal pitch curve for a rough -3/+10, you can set it something like: 35%, 42.5%, 50%, 72.5%, 95%, this is estimated number, but can be work like this.

As for throttle curve, I don't have a specific setting there since I run in governor mode, so I don't need any curve, but in the 2800 to 3000rpm head speed range is a good setting, just be sure to mold your curve to get a constant RPM.

** For any other brand, size of heli, these setting will be very different, but the pitch° value are around the same for a good set-up**
Last edited by martin_; Apr 01, 2011 at 02:18 PM.
Sign up now
to remove ads between posts
Mar 31, 2011, 11:31 AM
Registered User
Hi Martin,

Thanks for the info, I've got one in the post, that I'm going to use on my clone 450pro. I have a couple of flybarred heads to destroy before I try my flybarless one, and I was wondering if you can just use the tail gyro on the unit and switch the other two off for the time being?
Apr 01, 2011, 08:20 AM
Registered User
No you cannot use the unit as a tail gyro only.
Apr 01, 2011, 12:26 PM
Registered User
Originally Posted by martin_
No you cannot use the unit as a tail gyro only.
Thanks for the info,looks like I'll stick with the tail gyro for now then.
Apr 04, 2011, 08:37 PM
Thanks for the info. Just wondering whether these settings can be applied to a Trex 250 which has a similar layout to the 450?
Apr 05, 2011, 01:11 PM
Buy, Mod, Fly, Sell, Repeat
JHawk19's Avatar

Could a 2702V be added to a Dynam 250 E-Razor or an Exceed G2?
Apr 05, 2011, 07:05 PM
Registered User
If the helicopter is not identical and does not share the identical same parts than what I described, the set-up will be different.

I cannot tell you what the adjustment will be if the heli is not in front of me.

And yes this flybarless unit can be used on any eCCPM heli with a flybarless head, from 200 to 600 size, but for 500 size and up you should power your servo separately with a good power bus or make your own wiring.
Apr 06, 2011, 03:26 PM
Buy, Mod, Fly, Sell, Repeat
JHawk19's Avatar
One more question...Will one of these receivers work on an E-Sky CP3? Maybe the RX2612V?
Apr 07, 2011, 10:02 AM
Registered User
Originally Posted by JHawk19
One more question...Will one of these receivers work on an E-Sky CP3? Maybe the RX2612V?
I guess you plan to make your own flybarless head? If it's the case, the mechanical servo travel will have to have a ratio of 2:1 to the blade holder, otherwise it will not work very well.

The other possible problem is the tail control motor....

You will be better to buy the V400D02 flybarless stuff wich is from factory with a tail motor control.
Last edited by martin_; Apr 07, 2011 at 12:11 PM.
Jul 14, 2011, 03:15 PM
Registered User
Hello Martin,
i have bought the HK450 TT pro, a RX2702V and the HK450 Flybarless Bladeholder.

But i don`t know where should i mount the RX ?
Can you post some pictures from your installation please?

I have only one idea: the ESC under the battery tray, the Tail Servo on the tail boom like it`s mounted on the normal T-Rex and the RX under the Tail Serveo tray ..but many people say the 450 pro have a heavy tail.. so this is not good for right cg ??
But the Gyro tray is too small and the RX don`t fit in the chassis

please help

sorry for my bad english

Best Regards
from Germany

Last edited by ONDevil; Jul 15, 2011 at 07:34 AM.
Jul 18, 2011, 12:12 PM
Registered User
The best place to mount it is on the antirotation bracket, make your actual one longer with some plastic, or go to with a KDE direct one designed for flybarless unit:


Also the lead connector should be facing forward.

Before to install your elevator servo definitely, look at how the gyro make the elevator correction, if it's inversed, move your servo on the other side of the frame, do not rely on the gyro swith on the unit, that switch does not work properly and your heli will fly very bad, leave the switch in its original position, this is the only way to make work the 2702V correctly.

If you are beginner and at the hovering level, it's a very nice and stable set-up, but once you start to push the heli a little, it's very unstable, but anyway....... fly it and enjoy..!!
Jul 18, 2011, 03:46 PM
Registered User
thanks Martin,

a friend build me a special gyro etension braket like the Anti-Taco braket.

I hope the RX2702 make a good Job.. i have a microbeast in my T-Rex 250 and flies very well. I think the RX2702V is not as good but flyable

thanks for the TIP with the Nick Servo.

I report in a few weeks when the Bird flies

Some 3D Flights with my V120D02 and Tic Toc with my
T-Rex 250 FBL Microbeast @ Tennishalle Mössingen (6 min 43 sec)
Jul 19, 2011, 04:20 PM
Registered User
Firewolf's Avatar
Hey martin, great info. I've set it up on my Trex 450 pro clone with HK FBL head and the heli can be hovered hands free Though i am having trouble as the tail is not solid at all. I've tried my best to set everything correct related to tail but don't now what i am missing here

I am using TURNIGY DS480 as a tail servo.
Jul 20, 2011, 08:00 PM
Registered User
Hi Firewolf, on mine I used an Hitec HS5084mg, I ended up to put the ball link on the farthest hole, wich is about 12mm on the horn, and set my TX tail gain at 95%, there was only a slight wag at hovering but the tail was very fine in any other situation.

You can start with 10mm on the horn per the 450 pro manual, and if there is no binding anywhere, you should be fine.

What I found is that the gyro sensitivity adjusment (tail & cyclic) does not give a very wide scaling of adjustment, from 50% to 100% tail or for - to + on the pot, it does not make a big difference.
Jul 22, 2011, 08:16 AM
Registered User
Firewolf's Avatar
Thanks martin, i'll try to play some more with the settings. Will also try to change the tail servo and see if it makes any difference. I am also thinking of using an external tail gyro if nothing works out

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Official HK 450 PRO GT Thread 3D Belt / TT Drive Helicopter Kit Align T-Rex Pro Clone captaingeek Mini Helis 104 May 08, 2012 01:41 AM
For Sale Main drive Gear for T-rex 450 se v2 pro sport ucusclub Aircraft - Electric - Helis (FS/W) 1 Jun 18, 2011 04:02 AM
Question Do the T-Rex 450 Pro and Sport versions have a different main shaft from the old 450? Sky_Dancer Mini Helis 2 Oct 06, 2010 09:31 PM
Found WTB -= T-Rex 450 Pro Flybarred RotorHead =- Whopper Chopper Aircraft - Electric - Helis (FS/W) 1 Sep 06, 2010 06:14 AM