Is this too much? Battery question

[BBCorvette18]

Yea if i go full throttle the planes in the air instantly havent towed anything yet. The fun cub still.amazes me how slow and stable it is. I really think anyone can fly one

[CrimzonRider]

Originally Posted by Watts Cooking

It's a turnigy G25 610kv pulling 60 amps and a little over 800 watts. It takes off in less than a foot and tows up very large gliders with no problem. I also put my GoPro on it and fly that around without any problem.

What size prop you turning?

cr

[Watts Cooking]

It's a 12x8 slow fly prop that high a pitch on a slow fly moves a lot of air. The combo of motor and prop gives it a lot of torque and instant power whenever needed. It sounds a little unconventional but I have yet to see another fun cub out perform it. It flys nice and slow well and flys fast well, it tows up large balsa gliders well and does aerobatics well. It just flys great even when I fly my GoPro camera on it it doesn't even notice it.

[JetPlaneFlyer]

Watts,

I think you might want to check your numbers. I don't see any way a 610kv motor on 4s and a 12x8 would pull 60A I'd expect more like 25A on that set up and FWIW e-calc agrees with me (see attached)

Also if you did pull 800W at 60A that means only 13.3V, which is virtually low voltage cut-off for a 4s pack.. Something wrong somewhere I think?

[Watts Cooking]

Originally Posted by JetPlaneFlyer

Watts,

I think you might want to check your numbers. I don't see any way a 610kv motor on 4s and a 12x8 would pull 60A I'd expect more like 25A on that set up and FWIW e-calc agrees with me (see attached)

Also if you did pull 800W at 60A that means only 13.3V, which is virtually low voltage cut-off for a 4s pack.. Something wrong somewhere I think?

Unless my watt meter is lying to me and my friend who has the identical set up and my batteries are fully charged than the chart beats me. These are the numbers we get every time we test and its a 12x8 slow fly the slow fly props tend to pull more amps. If you want perfect numbers I think it was exactly 58 amps and 798 watts.

[JetPlaneFlyer]

The e-calc simulation was done with a slow-fly prop. But that was just done as a check as my own experience with similar kv motors gives me a good idea what amps to expect. Are you sure it's the 610kv version of the G25 you are running?

interestingly e-calc predicts 57A if you were using the 870Kv version!

[Watts Cooking]

Originally Posted by JetPlaneFlyer

The e-calc simulation was done with a slow-fly prop. But that was just done as a check as my own experience with similar kv motors gives me a good idea what amps to expect. Are you sure it's the 610kv version of the G25 you are running?

Yes I'm sure it's the 610k version I've been flying this plane a long time on this set up and it always reads the same numbers. My watt meter can't be lying and the real world facts I'm getting trump computer numbers on a calculation sheet I'm my opinion. My other friend is running the 710kv version of the G25 on 4s with a 12x8 three blade and his numbers are a little higher pushing almost a 1000 watts both tested with different watt meters so I doubt two meters are lying. Not trying to start a fight I'm just going with what i read on the meter and it hasn't failed me yet.

[r_kopka]

Originally Posted by solentlife

As illustration .... my Cessna 182 is factory specc'd for 3S 1300 pack. She flies fine on that ... but put my 3S 2280 pack in and she now carves up the sky much better ........ CoG still same as it sits on CoG mid point.
That little extra weight makes her punch wind better, can deliver higher amps, gives loooooong run time .... a much better all-round model for it.

It also works the other way round.

My Catalina(HVP 1,4m) had a heavy NiCd and brushed motors before. It barely came of the water and was a brick to fly. For a looping you had to use exactly the correct speed or it went wrong.
Now with Lipos and BL it weighs about 200g less (~20%) and it flies much better. No problem doing a rolling circle.

There are only very few planes which fly better with more weight.

RK

[JetPlaneFlyer]

Originally Posted by r_kopka

There are only very few planes which fly better with more weight.

RK

+1000... which is why we make planes out of balsa and foam and not cast iron and concrete

Weight is the enemy on any model plane as far as I'm concerned and should be minimised as far as possible. Only exception I can think of is a glider on a really windy day, maybe.

Famous full size airplane designer Burt Rutan is quoted as telling the engineers building one of his world record breaking planes that when they finish building a part, they must throw it up in the air for a weight test, and "If it comes down, it's too heavy"