this is the explanation of how they can fly upside down, your main throttle stick controls your pitch and how fast the blades spin, in stunt mode most set up so it is at 100% throttle no matter where the stick is moved to, now the stick only controols the pitch of the helcipter, when you flip upside down you move the throttle stick below half stick and you get in to negative pitch and that keeps the helicopter in the air
if you were flying normally and went into full negative pitch the helicopter would shoot twards the ground like a bullet instead of up in the air like it normally would, and if you flip upside down and you do not move the stick down to negative pitch u will also shoot twards the ground like a bullet.
RC air planes are a piece of cake compared to the helicopters, i got a air plane and was doing all kinds of flips, rolls, flying upside down, knive edge turns, some precision aerobatic moves and every thing else with in the first 5 min. and it only took me about 2 days to get extremely bored flying a air plane and could not wait to get my helicopter up in the air instead. the helicopters are such a challenge its not even funny...
the stuff the pros do would cost you a lot of money to learn unless you are naturally gifted and spend hours apon end on the RC flight simulators, one of the big 700 size nitro helicopters could require very much money to repair, you break one set of blades on the 700 size heli and your out 120 bucks just for the blades. if i have a bad crash with my bigger one its about 60 bucks in repair bills, average crash cost is about 20-30 bucks. my smaller one you saw me doing flips and inverted flight with usually cost 5-20 dolors to repair after a crash. it can be a expensive hobby but its very rewarding, i have busted a helicopter to pieces and came home excited and with a big smile cus i did a few really cool stunts before it hit the ground.
it is the most addicting ting i have ever got my self into and the biggest money pit, i cant quit buying stuff for these, i probably have close to 600 dolors in my big one now and need to spend about 3-4 hundred more to get every thing that i want for it so its a top notch machine... better this, better than, carbon fiber this, carbon fiber that... its worth it to me.
i also push my self extremely hard to learn new things i have advanced much faster than most of the guys on the forums that started around the same time i did, even some that have been flying for a few years, if you are afraid to crash it you will never learn and your progression will be extremely slow...
here is a picture of what you use to controol one of these helicopters, notice all the switches, buttons and there is a digital menu with about 30 screens you can go into to adjust settings for the helicopter too make it fly correctly or change the way it flys. and also here is a pic of my first bad crash lol...
