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| dnam | Veteran - Location: Herndon, VA - USA - My Posts This: Topic Forum |
Lehner on 4SJust a little update.
Well the Lehner does deliver on it's promise!  In it's weight category this is the most powerful motor I have ever seen!
I flew the Lehner with an 11t pinion (still using it as 3529KV) and got HS of around 2800-2900 with 80% throttle. It was very-very strong and would just zip the heli into the sky real fast given full pitch! The motor was drawing every bit of juice out of the 3S TP2100s as it could. Even 30amps and above, even though the batts are only supposed to be able to deliver 25 amps max. Thunder Power batteries are good! As from one of the above posts you can see I even measured 300 Watts and a little above with my wattmeter!
So I thought I have to try it on 4S TP2100s as the Lehner still has a lot of potencial left. Now get this! On 50% throttle with a 10t Eco8 pinion (smallest I could find with 1/8" / 3.17mm bore) HS is around 2800 AND it still pulls above 30 Amps with max power between 460-500 Watts!!! 
All this while I hold it in my hand with no bog at all for the first few seconds after applying full pitch. I use the heli governor mode on the Kontronik so it brings up the throttle of course given more pitch and there is a lot of headroom left for it to do it's job! Of course it will start to sag a little if I don't get off the pitch, but even then not that much bog...
I only had a half pack left to try it outside, but man this thing is POWERFUL! You know some of the vids you see (like the Lipoly heli with HS of 2600) with the heli just shooting into the sky like a rocket from standing on the ground? Well this is like that!
The extra weight of the 1 extra cell is far outweighed by the extra power. My Rexi was around 710g-s AUW with the 3S batts and now it is 765g-s AUW.
Just a rough comparison:
3S TP2100, 710g, 300W --> 0.42 Watt/gram
4S TP2100, 765g, 460W --> 0.60 Watt/gram
Here are some pictures. As the motor is mounted on top I can push in the batts a little further to get the CG perfect. Also you can see the Y-connector I made to connect two 2S batts in series. (The connector is a little heavy and accounts for 5-10g gain of weight)
Well, all in all I think I have found the setup I will settle with for now and am VERY happy with. It would be more efficient and have more torque (got way enough now though) to run higher throttle setting but I can't find a smaller pinion. This is OK actually because with the 10t pinion I can use it on 3S batts as well, just have to set the throttle higher. This is good as if I do not want all out power (not to say it is not enough on 3S) I can just use my 3S batts.
One last note. One could use 4S TP1320 but power to weight ratio wouldn't be as good as with 4S TP2100. The 1320s are rated at max 12C also, but I am sure they can deliver a little more. If they are like the 2100s than maybe 20% better burst performance? This then would be around 12x 1.32 x 1.2 = 19 Amps. I think it would look something like this with the 1320s:
4S TP1320, 690g, 280W --> 0.41 W/g
Interesting that it's around the same power to weight ratio as on 3S TP2100s.
Well, that's it for now.
Cheers!
Nam |
| 02-11-2005 Over year old. | | | |
