propane as fuel?
I am designing a top-secret device. However, i need to know whether i can use propane as its fuel source. i need enough thrust to lift a 120-pound weight (54.5 kg) about 3-5 in (roughly 6-11 cm) off the ground for a long time, until i turn it off or run out of fuel. I am wondering if propane is the best option for somebody who can not afford to spend a lot of money on expensive fuels. Also, can it work without any extra propellants, just air?