RCU Forums - View Single Post - Purple Brushless Electric Ultimate BiPe
Old 04-09-2008 | 02:06 PM
  #71  
opjose's Avatar
opjose
 
Joined: Nov 2005
Posts: 12,624
Likes: 0
Received 0 Likes on 0 Posts
From: Poolesville, MD
Default RE: Purple Brushless Electric Ultimate BiPe

Ok let's see:

The A22-15M is 1050kV and can handle 16A operating 20A peak with a 10x5 prop.

A 3S Lipo battery is suggested... so...

20A x 11v = 220 watts.


At

11v x 1050kv = 11550 RPM's

You'll get around 50oz thrust or so at max.



The A22-20L is 1000kv and can handle 21A operating and 25A peak with a 11x5 prop.


25A x 11v = 275 watts.

You'll get around 68 oz thrust or so at max.

You'll have a higher power to weight ratio with this motor, but the prop size may be an issue.
You may want to go with a smaller higher pitch prop, say a 10x6 instead...


IMHO the Eskay 400XT is not powerful enough for this plane, so forget it.


The second motor is a bit heavier, but there have been people here having problems getting enough weight in the nose, so go for the second motor with the slightly smaller higher pitch prop.

You may want to look at getting something like a Kokam 3A2P 2000mA battery pack such as the 834374-3S... or the similiar 2500mA pack.

See: [link=http://www.kokamamerica.com/ka/rc.aspx]Click me![/link]

Why use one of these packs?

Because the battery is configured in a 3S2P arrangement, the battery is not as long as standard 1800mAh or even 2200mAh packs, but it is "wider" instead.

This lets you move the bulk of the battery weight forward towards the firewall to balance the plane, or also shove it back into the body.

There was one person here who obtained was unable to obtain C.G. figures because both his motor and battery were too light, and he could not move his pack forward any further.

I use a very similiar 3200mAh 3S2P 11v helicopter battery packs and this works great... ( rc-smart ) but they are no longer listed.