hi
can anyone advise on best electric set-up
for 5 metre ka8 glider
ir weighs 9.5 kg
i havent a clue , so any help would be great thanks
mick
Re: ka8 electrified
Posted: 13 Jul 2017, 09:07
by Barry_Cole
Mick,
I depends a lot on what you want the motor to do...
If you just want power to get you back to the top of a slope, that is one option.
If you want it to take off from a dolly, then that is a different option.
Can you give us an idea of what you require.
BC
Re: ka8 electrified
Posted: 13 Jul 2017, 10:25
by mick a
hi Barry
thanks for the reply
i would like to take off from dolly
i dont want it to be ballistic , just something
for a nice steady climb
hope that helps ?
Re: ka8 electrified
Posted: 13 Jul 2017, 10:55
by terry white
Hi Mick i'm sure I can help you, been flying large scale E. power for a long time now, but I'm just off to Shropshire to fly in the Mynd fly-in get together (no E.power allowed on the Mynd though) I will post when I get back if you haven't heard from others. Regards Terry.
Re: ka8 electrified
Posted: 13 Jul 2017, 14:10
by Jolly Roger
Hi Mick,
At 21lbs weight I'd want at least 1200W of power for ROG. You can get this from a 6s LiPo which is handy because any bigger and you need to pay lots more for your battery/ESC/charger.
A 6s battery gives you about 22V voltage (that's 6 cells at 3.7V per cell), meaning you need to draw a current of about 55A to get the 1200W power (because power = voltage x current).
To get a 55A current you need a motor with the correct kV and a prop to match. I suggest looking at the motor / prop combos used successfully by Chris Williams for models of comparable size/weight. He often details them on his excellent videos. It's got to be a good starting point.
Hope this helps. Sorry I have no 6s set-ups of my own to recommend. Good luck.
Rog
Re: ka8 electrified
Posted: 13 Jul 2017, 14:12
by chris williams
Turnigy very helpfully name their range of motors to compare directly with glow motors. Thus the G60 is rated as similar to a .60 glow motor, and can very conveniently run on 2 x 3s's. My Super Javelot flies well on the 500Kv version, although there might not be enough power to get off a dolly.
thankyou very much gents
its really helpful , will have a look at the turnigy
as im a nitro dinosour so understand that bit
is it around 100 w per lb i need ?
or could i get away with 70w per lb
thanks again for all your help
mick
Re: ka8 electrified
Posted: 14 Jul 2017, 07:51
by Barry_Cole
If you want to go off a dolly, go for the 100 W/Lb.
BC
Re: ka8 electrified
Posted: 14 Jul 2017, 08:57
by RobbieB
Barry_Cole wrote:'If you want to go off a dolly..................'
So tempting...........
Re: ka8 electrified
Posted: 14 Jul 2017, 09:06
by Barry_Cole
Down boy, stay calm......
BC
Re: ka8 electrified
Posted: 14 Jul 2017, 22:12
by Jolly Roger
mick a wrote:thankyou very much gents
its really helpful , will have a look at the turnigy
as im a nitro dinosour so understand that bit
is it around 100 w per lb i need ?
or could i get away with 70w per lb
thanks again for all your help
mick
Not wishing to contradict others, but I think 70W/lb is plenty for your relatively lightly loaded, high-lift sectioned model, providing the prop diameter is reasonable and the grass isn't too long. My 30lb Super Cub leaps into the air on <70W/lb. Go for 100W only if you want a healthy safety margin of power, but either move up to 8s+ or if sticking with 6s remember the batteries/ESC/motor will have to deal with 100A.
Rog
Re: ka8 electrified
Posted: 15 Jul 2017, 09:00
by mick a
Thank you gents
I was trying to get pic on but all to big
Not too big by any means, not sure why you had a problem. BC