This article is from the Radio Control (R/C) Flying FAQ, by Shamim Mohamed email@example.com with numerous contributions by others.
A: SC is the basic cell. SC cells will take fast charging and have
reasonably low internal resistance. SCR cells have lower internal
resistance and a somewhat flatter discharge curve, that is, they put
out nearly the same voltage from beginning to end of the discharge.
SCRs are best for high current drain applications. SCE cells have
somewhat more capacity for the same physical size, but also have
higher internal resistance. They are best for low current drain
use (less than about 10 Amps.) The higher capacity of SCE cells
will not be realized at high current drains, and they will heat up
more than SCR cells.
Many kits nowadays come with a power system. In most cases, these systems
are adequate for the application. It won't hurt to try what's there to
start with, you can always experiment later. If the kit you choose doesn't
come with a motor, of course, you'll have to choose one. If you are a
beginner, go with the recommendations of the kit manufacturer. If you are
an experienced RCer, you probably don't need my help.
For a six- or seven-cell glider or old-timer with a cheap motor, an on-off
switch is sufficient control. For anything else, you will have much
greater enjoyment with a proportional throttle. Get a high-rate control,
they are much more efficient at part throttle. There are several good
brands out there, but I like Jomar for good controls at good prices.