http://www.infinity-hobby.com/main/article_info.php?articles_id=300O.S. выпускает бензиновый двиг

забавно.
Is the power of 15cc gas engine enough?
It is predictable that the ignite point of gas is higher than nitro, and the power is not big as nitro. This is why pilots modified gas engine usually used at least 23~26cc engine on 90 grade helicopter. The power of these modified engine is enough, but the weight of a 26cc gas engine is about 1.6~1.7 kg. Under the same rotor disk, higher displacement gas engine can satisfy the demand of torque, but it is too heavy and lack of flexibility.
The power of GT15 is only 2.8ps, but the weight including CDI igniter is only 798g. The displacement is only 15cc, but the power-to-weight ratio is quite good. Please refer to the calculation below:
OS50SX (1.9ps)+T-REX600N take-off weight: 3,400g, power-to-weight ratio: 0.558ps/1kg
OS55HZ (2.1ps)+T-REX600N take-off weight: 3,400g, power-to-weight ratio: 0.617ps/1kg
OS91HZ (3.4ps)+T-REX700N take-off weight: 4,900g, power-to-weight ratio: 0.693ps/1kg
OS GT15HZ (2.8ps)+T-REX700N take-off weight: 5,073g, power-to-weight ratio: 0.552ps/1kg
ЗЫ. сам я не решился на него, неспешно собираю 700ку со 105ым мотором.