hi,
I dont know what is ur level of experience. but u seem to be choosing ur project wrongly. either ur are underestimating this hobby or having half knowledge.
Anthing can fly if
you have the proper knowledge and
if you have the right skills to fly.
you should be first taking all the required info from the net and then study the plans and understand power requirement. the C-17 globemaster will require at least 4 edfs . accordingly 4 lipos. edfs take a lot of current and hence the flight time is very little.
http://www.fanjetsusa.com/90-120mm_Set_Up_Guide.htmlsee the above link.
regds
sandeep