lipo packs don't tend to get hot like nimh/nicad, so battery cooling isn't a big factor in designing the aircraft. Motor cooling, however, is another story. Motors that never got hot with 8 to 10 minute flights tend to get rather "tasty" with 30 minute flights, so more motor cooling should be planned for, or, more efficient motors like the hacker C50's. Talked with Sean this morning (importer of hacker motors). They've flown the rhapsody's and performance is good, but they are a couple ounces over the weight limit. Currently have large rx packs and big servos everywhere, so that little "problem" will be recitifed shortly. The 10-cell lipo setup is working well, spinning a 20X13 prop in the mid 6K range. The only negative is that speed is a bit high, so they might actually have to prop down and reduce power a bit .