Greg
its the powerplant you need to consider
engine plus propeller
You need to calculate the thrust, based on prop, rpm and required torque/bhp
at 6000 rpm with a 19x8 APC you get 13.4 lb of static thrust.

when flying
T*V/550=bhp
select a thrust and use a drag coefficient of about .3
D=1/2. rho. V^2. S. Cd = T
at 45mph
V=66fps
V^2=4356
rho apprxs to 2/29^2 = .002378 at 59degF S/L ISA
S= wing plan area ; say 5 ft^2
so the drag is 7.8 lbf =thrust for steady flight is .94 bhp

I am not sure what the Cd of your plane is
it could be as high as .4 because of the Reynolds number you are flying at

The prop will not develop 13.8 lbf of thrust at that speed
see also
http://www.mh-aerotools.de/airfoils/propuls4.htm

I just maidened my 3D hobbyshop Edge 540 74" electric in Margaree last week.

This is my setup:
6S Hacker A5012L
Castle ICE-100
Castle Creations BEC Pro
Xoar PJM-E 20x10 Prop
Turnigy nano-tech 6000mah 6S 25~50C Lipo Pack

I haven't pushed the plane very hard yet as I am breaking the packs in.  But it flys great and I am getting at least 7 min flights with power to spare.

Plane weighs about 10.5 to 11 pounds and we calculated the thrust using the 7 in 1 HK meter to somewhere around 21 pounds swinging the 21x10 at 6600 RPM.

In retrospect it might have made more sense to use a Life pack rather than the bec because I had to add about 100 grams to the nose to balance the aircraft.

Also 8S would probably have been a good choice but I felt 6S was a simpler option for me and I saw youtube videos of the 6S setup and was impressed with the flying time and characteristics of the plane on that setup.

all fine and dandy, but how many sparks do they explode with 

Hi Guys
Keep up the good work.
In pattern a year ago this was called the dark side.Now It seems to be the norm.I can see it all now, we will all be flying Electric in a few years. No more glow and Gas planes. Wonder what the turbine boys will do.
Grant

Grant wrote on Jun 22^nd, 2012 at 7:44pm:


I don't think turbines will go the way of the do do bird like glow engines currently going.  Part of the attraction of turbines, atleast for me, is the whole experience....the smell, the flames at startup, the sound and the realism.  You don't get that with EDF.  While EDF's are definately easy and convenient, their will always be a place for turbines imho.

In 10 years, the only guys running glow engines will be doing so just for nostalgia purposes.  I also predict that glow fuel will be the final nail in the coffin as the price will climb as fewer and fewer guys will be buying fuel.  Most of the new guys at my field (less than 2 years experience) are going all electric from the get go and not even bothering with glow.  I, myself, am going all electric from here on out.  Just picked up a 800w charger, 800 watt power supply and a 2000w honda generator.