What power source should I use?
 

I'm planning on using the GreatPlanes S-600R motor in a plane with wing loading of 16-17 oz/sq ft. The prop that comes with the motor and gearbox is a APC 9x8 (a 10x8 is recommended in the kit manual). I also plan on using an ESC w/BEC.

I'd like to get as much runtime out of this setup as I can. I'm on a limited budget however and concerned with weight.

I've been reading about Lipoly and 3000mAh NiMH batts.

LiPolys look very cool for runtime sake but the closest voltage I can get would be like 7.4 and they are a little pricey.

It's not like 3000mAh NiMH batts are cheap either.

Any recommendations?

Now will they fit?
 

I was able to find 3000mAh NiMH batts from radicalrc.

Looks like less than $42.50 for a 7 cell.

Now I wonder if these would fit into an GP ElectriCUB.

What would the flight time be with a 7 cell pack?

How are these in comparison to 1700-AUP packs?

What power source should I use?
 

You're going to pay for bleeding edge technology, that's for sure.

A 7.4 LiPoly pack is actually a fair equivalent to a 7-cell NiMH pack, when properly sized to handle the current required by the motor. At full charge, they are actually 8.4V, and hold their voltage better under load. However, as you said, they are VERY expensive, and I recommend against newbies using LiPolys, because you need to treat them special. Newbies are bound to ruin a pack or two in the learning process, and I feel it's much better to learn on something that isn't so expensive and is less likely to redecorate your house if you mistreat it.

The 3000mAh NiMH cells are a good choice, but they are a fair bit heavier than CP1700s. I don't think they'll impact the flight characteristics of the plane much, though. They ought to fit in a "flat" configuration (side by side) and should give you fairly impressive flight times. Adding an 8th cell will give you about 25% more top-end power, and would allow you to run at a lower throttle setting, extending your flight times.

What power source should I use?
 

Would it be better to purchase a prebuilt pack or to build one myself?

It is rather hard to find 3000mAh cells. I can find packs without too much difficulty but finding the sanyo or panasonic cells have been quite a trick. What are good resources for finding good prices on these?

Would an 8th cell effect the life of the motor?

I'll definitely hold off on the LiPolys for a while...

Thanks for the info

What power source should I use?
 

There are a few different types of cells in that range, like the GP3300, the Sanyo HRSC2600, etc..

If this was the "other" site, I'd recommend you to their sponsors page, because there are a lot of vendors there that handle the cells, provide good service, and have fair prices.

However, try http://www.dynamoelectrics.com.

8 cells won't hurt the motor. In fact, it may actually extend motor life because you will be able to trade Amps for RPMs. Amps create heat, and heat is what kills the motor.