yogi,
you get different sorts; self launchers (gets off the deck itself) and self sustainers (can't get off the deck, but enough to stop it going down too much...!)
They tend to have engines to allow them to get to soarable conditions not exploitable from a winch launch or dubious even from aerotow.
But with the iron thermal in the fuselage behind your head, it's a very noisey experience, with the cockpit acting as a huge soundbox and amplifier, so we don't have 'em on for much longer than necessary!