[tech1]

Ok so this won't be what you are thinking.

I fly a large electric heli. Everything has been running smooth so why tinker? It wouldn't be fun if you didn't.

The interesting thing about electric heli's is it is easier to measure what is happening to the heli. By keeping track of time and current you can easily figure how much power it takes to fly. From there you can also track trends to see if performance is changing.

I switched from 680mm to 710mm blades to see what happens. No other settings were changed. Here is what I found.
- performance was more solid. It did have marginally more power and lift. The hover point on the throttle stick was more touchy. (As if the throttle curve had been raised)
- Tough to say if it was more steady. The last time I flew was in 45Km/h winds.
- Here is the Math side...... It takes 20% more power to spin the blades. The 2 flight packs both drew about 20% more current in flight. This would drop flight times by about 2 minutes.

So the options are get more power for a slight loss in run time, or stretch the flight out with a little less "pep".
Both are valid options.

If you have similar info, I'd like to hear about it

[G-copterbous-funk]

Or you can just fly the thing and note how it degrades. Bogging sets in earlier as engines wear (batteries degrade) or things are set poorly. If you can pull the same pitch today using the same stuff as yesterday then things are still working the same. Add longer blades generally reduce top pitch or maybe add nitro The thing about slightly longer blades is there isn't always a power handicap as all blades are not created equal.

The thing about electrics is efficency, similar voltage/current ratings can produce different power with different speed controllers and motors. Electrical power consumption is not a guarantee of rotor shaft torque and you are faced with optimal gear ratios just like a glow. Flight testing with pilot evaluation is what really decides for both nitro and electric. Nitro has the advantage of caring little for flight duration limitations.

Stephen

[tech1]

-Power does factor into rotor shaft torque. It takes more torque to swing longer, heavier, higher drag blades. This relates directly to how much power and electric or gas heli requires.

I did notice it took less pitch to hover. (higher lift blades) but in climbing the motor was working harder. In my nitro machine I would have changed the needle setting and throttle curve to compensate to add more power earlier in the curve.

- I would bet you will have less flight times on your nitro machine by switching from 680mm to 710mm blades. I never timed my nitro flights because I flew by visual on the fuel tank. Would you know if your tank lasted you 12 versus 14 minutes?

[G-copterbous-funk]

Electrical power is amps X volts. Some motors will give more shaft hp per a given electrical consumption. Most will give lower efficency at a poor rpm even though they are eating electrical current. When the motor is stalled/bogged it uses more power and looses efficency thus producing less work at the rotor shaft. You may have read something in my post that was not intended.


the point is you'll learn more about the model behavior during a test flight than an amp meter will tell you.


Stephen

[tech1]

I agree with that.

The numbers help you to understand what the TX sticks are not telling you. When you boost the performance of the heli, (which I did notice with the 710's) what is the cost?

In my case, the 710 blades are well within the power rating of the motor. After a 10 minute flight, the battery and motor were warm. As compared to cool for the 680's. I know by how much now. All this gives a good idea of the performance envelope of the helicopter and motor.
The equivalent in nitro would be a hotter running motor from the heavier load. My original point is that this is easier to measure on electrics. It is easier to find out how things are running if you are interested.