800e at 1300rpm - HeliFreak
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Old 12-22-2016, 08:56 PM   #1 (permalink)
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Default 800e at 1300rpm

I stretched my old 700e (V1) to an 800 with the ALIGN kit, swapped the old 700mx 510kV motor for a 800mx 440kV motor. According to Mr. Mels, and CC gov, I can run 1300, 1500, and 1750 rpms. Main gear has 115 teeth and opinions 12t, on 12S. Will this be enjoyable at these speeds especially at 1300 for mild 3D, sport and big sky? Or will it be working hard?
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Old 12-23-2016, 04:47 AM   #2 (permalink)
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1300 rpm on an 800 size machine is still very high. So you should get enough rpm for lift and at that level even 12 degrees pitch work great.

On any lower rpm settings the most critical part is tail authority and if the motor/esc combo is able to hold rpm level well enough. I am not sure about gear ratio for the tail -> 4.7 is the minimum you should have. Below that it can be tough. Also - if rpm on the motor goes down to much you also run into an issue with your tail kicking out.

The helis most often have enough lift for a 800 machine even at 700 - 800 rpm. As stated your enemy is more motor power and governor on ESC as well as gear ratio.
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Old 12-23-2016, 04:24 PM   #3 (permalink)
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I hovered it today at 1300, 1500 and 1750, seems nice, but waiting for a real flight. Its cold dark and snowing here now, but looking forward to a 5 min flight at 1300. As far as tail kick, when should I be aware of this possibly happening?
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Old 12-23-2016, 05:26 PM   #4 (permalink)
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1300 is my low headspeed on 600 heli, but its not low for a 800.

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Old 12-23-2016, 05:33 PM   #5 (permalink)
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Quote:
Originally Posted by reALIGNed View Post
I stretched my old 700e (V1) to an 800 with the ALIGN kit, swapped the old 700mx 510kV motor for a 800mx 440kV motor. According to Mr. Mels, and CC gov, I can run 1300, 1500, and 1750 rpms. Main gear has 115 teeth and opinions 12t, on 12S. Will this be enjoyable at these speeds especially at 1300 for mild 3D, sport and big sky? Or will it be working hard?
The common misconception is 12s will always run cooler than 6s. Not this case during low rpm flights.

Low rpm is extremely low demanding on motor and battery (due to reduced current draw from exponentially lower parasitic drag). Therefore you can safely run on 6s (one 6s5000 or two 6s5000s connected in parallel) and your older and smaller/lighter 510kv motor.

510kv x 6s x 3.7v x 12t / 115t x 90% throttle x 90% efficiency = 956rpm.
440kv x 6s x 3.7v x 12t / 115t x 90% throttle x 90% efficiency = 826rpm

I recommend that maybe you get a 13t pinion, the calculation will be

510kv x 6s x 3.7v x 13t / 115t x 90% throttle x 90% efficiency = 1037rpm (my recommendation)
440kv x 6s x 3.7v x 13t / 115t x 90% throttle x 90% efficiency = 894rpm.

On 6s at 90% throttle, your motor and ESC will remain cold no matter how long and how hard you fly.

Of course get the align 3-blade tail with 115mm blades if you want to have good tail authority.

Good luck.
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Old 12-23-2016, 06:01 PM   #6 (permalink)
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Its kind of hard to swap pinions with this model, it has the fixed motor mount. I do however have an adjustable motor mount made by Lynx but I'm also not looking for a lowest flyable hs. Mainly wondering if 1300, 1500, 1750 will do harm.
Lots of good mathematics though, makes me think about 6S in parallel. Thanks
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Old 12-23-2016, 06:52 PM   #7 (permalink)
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sure - an 800 can normally do slow 3d at about 800 rpm. However I always advice people to try bringing it down slowly and develop a feeling. Again tail authority has to be at manageable level. Head speed is the easier part.

1300 for someone not done it before is low. I fly a 700 down to 800 and a 500 size down to 1300 for slow motion 3d. However - took me a while to get used to it so always be careful. No need to risk the heli.
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Old 12-23-2016, 07:29 PM   #8 (permalink)
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I get what your saying and I appreciate it too, the weather up here is not the best but I cannot wait until spring to test this bird out, but once I get a break in the temps, I'll def give it a few flights. Just looking for some long enjoyable sport flights. With my stock 700e set up stretched to 800 it would fly for about 3-4 mins., and the motor and batteries were very warm at (1800 rpm), I could not find a 10t pinion to lighten the load, so I found this new motor (ALIGN 800mx 440kV), according to MrMels calc. and CC's gov., it should work nicely and thats where I'm at.
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Old 12-24-2016, 09:08 AM   #9 (permalink)
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When I was flying an 800 raptor I had 1100 as the low rpm, 1600 as the high rpm. At one point I put a gps sensor in it just out of curiosity and recorded just over 100mph at 1600 with spin red tip blades. I think it was 106mph,.. so not blazing, but certainly not slow. later changed to align 800 blades as they would bite more at the lowest rpm, although they took some of the speed away at high revs.At 1100 it still performed well for my style of "geriatric 3d" . Lotsa pitch, I think it was 16 degrees in the lowest rev flight mode, but it's been a couple years ago, so not sure. There's a short video on the other site at

http://rc.runryder.com/helicopter/rr.../HE2014-11.mp4
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Old 12-24-2016, 11:58 AM   #10 (permalink)
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Nice video, love the barking blades
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