Charles,
For a Nobler, my battery energy consumption ---from taking the average watts on the plot *5 minutes --which is my actual flying time from takeoff to power out---that's what I set in the timer-- is 284 watts *5min/(60min/h) =24 watt-hours.

I include the plot. The input power in watts is the orange curve.

Charles,
I'm impressed you are still up!

One comment---I tend to be on the low side of power usage--others are using (I think) somewhat more so you should take that into account, especially before buying the battery. Also the Nobler is a thinner airfoil plane, so you may need more for a Pathfinder. I have a Pathfinder kit almost framed up (ashamedly now for more than 6 or 7 years!) and the wing is reasonably thicker than the Nobler, not to mention that the Nobler is a tapered airfoil, whereas the Pathfinder has the same thickness and chord all the way out.

I have just modified a Brodak P40 Arf (used previously with a Brodak 40 that was a really sweet flyer) to electric. I need to re-tack the covering back down-sitting for a summer up in my attic didn't do it any favors. I think it is comparable to the Pathfinder in size, so I am curious as to how it will turn out. Stay tuned! (but be warned we had 40 mph winds today, and some snow is predicted for the weekend, so it may be a while before I can get a flight with my data logger in). I have had one flight a week ago with the Nobler. Weather in the Chicago area is pretty variable in the Spring.

I'm using the Eagletree e-logger with the brushless rpm sensor. I also have an altimeter and airspeed sensor that works with it, but they are clearly not a necessity! The e-logger itself records average battery current and voltage (and calculates power), and with the rpm sensor it records rpm too. Here is a link. The e-logger downloads to a Windows PC application

http://www.eagletreesystems.com/MicroPower/micro.htm

I think it is pretty nice to see what is going on during a flight.

One comment, you may not be into competition, but you do want enough power for a good 5 minute stunt flight I think. Also you should know that you want to keep at least a 20% reserve left in the battery at the end of the flight--it prolongs the battery life according to Lithium Polymer folklore.  So to add to your information, my Nobler is flying on 62 foot handle to plane center lines.

Hello Charles,
For a full schedule how about 0.7 Watt-Hours on 67' of line, with the consumption varying almost linearly with line length.
Regards,
Dean P.

Hi Crist,
How about 0.7 W-H per ounce when flying on 67'
On 60' it will be maybe 10% less or close to 0.63 W-H per ounce, and maybe 0.73  W-H per ounce on the full 70'.

I should have been more clear,
Dean

Crist,
If you get a substantially different figure, let me know.
Dean