T-rex 450 Pro-Lite

[Eric Tessmer]

T-Rex 450 Pro-Lite
Just thougt I would share this information for anyone interested in making a light-weight setup on a T-Rex 450.

After hearing so much how lighter disk-loading helis fly better and my experience flying and designing 3D planes – I wanted to see what I could do to make a light heli set up. After considering several options, I decided to use a T-Rex Pro as my platform because this has a light frame setup to start with. I bought an inexpensive HK 450Pro and converted to FBL head ($12.50) with a Walkera 2702V 3-axis Gyro/Receiver (since I already use a Walkera 2801-Pro TX). The upshot is that I took 6 ozs off of the stock heli setup and this heli flies fantastic – like a 600 size – smooth and controlled, but also super-fast and crisp. I can even fly hands off (for a few seconds). How did save weight? By the following:
1) Drilled holes in many of the plastic parts
2) Dermaled out areas of the CF frame (trying not to compromise rigidity or strength)
3) Replaced stock canopy with a Walkera 400 size canopy
4) Replaced T-boom struts with shorter lighter ones
5) Used a lighter motor setup (Turnigy typhoon 2218H)
6) Used a light Phoenix 35 ESC
7) Using light 1800MAH batteries
8) Going FBL with 3-Axis Gyro/Receiver combo

I also own 5 other Trex-Pros, Sports, and V2 helis and have flown friends 500-600 class Trex helis, and this is my favorite by far. Another of my Pros with the Align 3G setup and Scorpion 2221-8 weighs 30 ozs compare to this one at 23 ozs. Even with the lower MAH battery (I normally fly 2200 in my 450s) due the light setup, I still get 5-6 minutes of flight time.

I love the Walkera 2702V 3-Axis/Receiver – it is super light, easy to setup and it has giving me way less problems than my 3G and performs better. No bobble on half flips, no porpoising on high speed FFF, tails hold rock steady on hard collective punches

[didgeridoo]

Wow! 23 percent weight savings! Talk about Slim-Fast! One ounce off for the canopy is great, too. Just curious- did you happen to measure just the frame mod savings? And, did you come up with the rudder servo mount yourself? Nice little chunk of plastic gone! How did your CG change? I've found them to be a little tail heavy to begin with.
I'm waiting on a the new Tarot FBL (black) head, which looks shorter (to bring disk closer to the load), and maybe lighter than the old Tarot FBL (blue) head.
-Didgeridoo

[Eric Tessmer]

Didger, no I did not measure the weight on the frame mod, but I guess it was about another ounce. Yes, my own invention on the tail servo mount. With short tail boom struts and dremeled-out tail fin, CG was not bad, just had to move the 1800mah battery far forward and it came out fine. Good luck with your Tarot - I am thinking about getting the new Tarot 450Pro FBL V2.

[didgeridoo]

Thanks for all the great info. You've inspired me rogue it a try. Merry Christmas!

[amiteini]

That was very helpful

[Eric Tessmer]

I am glad you like it. This was a rewarding project.

[kelleysislander]

Hi Eric,

I was researching "Walkera 2702 set up" and came across this post...

I have tried to decide exactly how this should be set up from the beginning through the calibration steps because I have read conflicting advice...

One fellow says initially set the SWATS AIL/ELE to 80/80 and set the PIT to 40 (half of the AIL or ELE value) because you must do that to get the cyclic pitch correct; the sheet from Wow says set to 70% / 70% / 70% for all three and set up as normal.

How did you go about setting up yours from the initial settings for the mechanical setup to the swash and rudder calibrations? Did you change any of the SWAATS values after the initial mechanical setup?

Thanks,

Bill

[Eric Tessmer]

Bill, I bought my 2702V2 from Wow Hobbies and received it with the attached setup guide which proved helpful and reliable. I hope this helps.

[kelleysislander]

Hi Eric,

I also bought my 2702 from Wow and what they gave me for a guide is not exactly what you received. I got a spreadsheet with typical ccpm settings for a computer radio and a photocopied excerpt from the V450D01 manual, but what was lacking was the "STEP 2" and "STEP 3" parts that are not part of the original manual.

Speaking of Wow, their price is $129.99 based on their claim of a $31.66 price increase that Walkera put to discourage the use of this receiver outside of their line of helis. That was so disingenuous just on its face:

Why would anyone want to discourage the appropriate use of their product when doing so leads to fewer sales?

That was just a money grab because you can get the same receiver here for $98.99...

(as a noob on this forum I was unable to post a link, but it is available at www dot oomodel dot com- just put "2702" into the search field at the very top and it will be the first listed result.)

Thanks again for sharing - now all of my cognitive dissonance has evaporated...

Thanks,

Bill

[kelleysislander]

OK, so the tail servo moves WAAAAAAAAY too far in either direction after setting the RX limits. To set the tail I flipped the switch to "Tail Set" and set the RX travel left and right, pressed the button, etc.

So I think the next thing is to set the Travel of the tail but when I limit the travel to like 25% left and 25% right which is what I need to avoid binding, the tail servo moves real slowly like I have lost the snappy reaction when I had full throw. It seems to get a bit better when I set the rate from HH to Rate Mode.

Any suggestions here for setting up the tail so that the linkage doesn't bind and pop off?

Should I be pushing the stick all the way before setting the throw by pressing the button, or should I be watching the tail pitch slider and pressing the set button when it gets to the end before binding? If I do that it only takes about 1/4" of push on the stick to get the slider to bottom out as the slider keeps moving after I stop moving the stick

Thanks,

Bill

[kelleysislander]

...so I am posting what I found in case someone else has the same "problem" as me in understanding the bad translation of a manual that we've all come to know from Walkera et. al.

Setting the rudder limits on a Walkera 2702V rx:

When setting the left and right rudder limits it is important to know that you are setting the position of the servo arm, not the position of the stick which is the case when setting the AIL and ELEV limits. When setting the left rudder travel you gently push the stick to the left and "miraculously" the servo arm keeps creeping after you stop the stick, which was what was throwing me off.

NOTE: It doesn't matter where the stick is when you press the button, just where the rudder servo arm actually is when you press the "SET" button.

In case you overshoot which is very easy to do thanks to the creep, all you do is bring the servo arm back to where you want it by moving the stick to the right as needed. Remember - all that matters is where the servo arm is when you press "SET", so once you get it where you want it and press "SET" you are recording the actual position of the servo, not the stick... The same holds true for the right side.

Anyways, I hope this helps someone in the future!

Cheers,

Bill