Streching Trex 700 to 800 with KDE 395 motor

[neesham]

Hi guys,

May be this has been posted before but I haven't found much on search engines. Im trying to Strech my 700 to 800 to accommodate heavy payload (assuming the AUW is 20lb) swinging 800mm symmetrical blades, 9.33 gear ratio, KDE 700XF-395 motor on CC 160HV ice2. Aiming for governed at 88-90% giving me around 1550-1580 rpm. How does this sound? Had anyone experimented with the same setup? Please share your thoughts/experiences. Thanks

[neesham]

Thanks CEFutcher. Wonder is it had any effects on the stability, like wobble when you went back to asymmetrical 700mm? the main issue with me when I am with the trext 700 stock with heavy payloads (5DMkII, + 16-35 2.8L) is a wobble when coming to stationary from a forward flight. After experimenting I was assuming the wobble is due to the 695 mm blades and the 510kv bogging down, and decided to go with 800mm + 395kv for more toque.

[neesham]

Finally got all the parts and flew the 800. Performs smooth and slow. lots of Inertia and very powerful indeed. No wobbles at the 700 even with payloads feels like the heli is Over powered. Didnt expect it to hower at 5.5 degrees of pitch, but it did. Tested with 1400, 1450,1500 rpm. All flies well except at 1400 motor is a bot hotter than at 1450, 1500.

[wonderd]

I also have a streched 700, working with 300kv xera motor and 120A conroller, the rpm is about 1200-1250 no wobbles or any weird behavior and the heli stays in the air for about 15 minutes..
it draws about 8 amps in avarage - so you don't need such big ESC...

[neesham]

thanks wonderd, It draws 8 amps without additional payload? what is your total AUW? my 800 weighs around 20lbs together with the camera, etc.

[helicek]

Originally Posted by wonderd

I also have a streched 700, working with 300kv xera motor and 120A conroller, the rpm is about 1200-1250 no wobbles or any weird behavior and the heli stays in the air for about 15 minutes..
it draws about 8 amps in avarage - so you don't need such big ESC...

Hi Wonderd,
8 amps current draw sounds very low. At 75% efficiency on 5000mah LiPo you can hover for 28 min.
Yes?

Originally Posted by neesham

thanks wonderd, It draws 8 amps without additional payload? what is your total AUW? my 800 weighs around 20lbs together with the camera, etc.

Hi Neesham,
My t-rex F3C draws 25 amps during hover at 1250rpm nr sea level. My setup is: Xera 4035-3Y-400, ice 120hv v2 and 80cm align blades. AUW is 9,5kg inc 2x5800 6S PS1 mount and D550/sigma 8-18. I fly on Ace One. I have not timed my flight but I keep it under 8mins. I land when my 12S pack nears 40volts. I fly Jeti 2.4 with telemetry on an old JR 9X II.
Cheers,
Ahmet