At the house I have a Gasser type helicopter (weed eater / chainsaw engine type) that could fly for more than 25 minutes on one tank of gas.

The drawback? It is huge! One blade alone is over 25 inches in length. Put them both together and you have close to 60 inches of rotor head diameter.

I think you need to go back and do a little more research.

Why do you need 30 minutes of flight time? On my nitro birds, after about 8 minutes I'm ready to take a break. With my gasser with a "relaxed" type of flying, i could go for about 15 minutes. After that my neck and my arms need a rest. I can't see flying more than 20 minutes at a time.

Rafael