Reply #8: The old Joke about Turbines, they have two speeds, Fast and Off [View All]

[happyslug]

Thus in hybrid would be the ideal engine, when on, excess power goes to charge the batteries. Thus the turbines disadvantages are minimized.

In jets the engines tend to be used at maximum efficiency, with some power left over for faster speeds. Most additional speeds for Jet engines are obtain through the design of the inlets (Inlet design is critical for jets, jet engined can NOT burn air going faster then the speed of sound, so the inlets MUST slow the air flow down in supersonic jets, after burners are used to go supersonic, i.e. shooting additional fuel into the exhaust to provide more power).

The SR-71, the first three times the speed of sound spy plane, something like 2/3 of its speed was obtain via the inlets, that is why such jets are expensive to make and maintain compared to Commercial Passenger jets, which do not go near the speed of sound (The Concorde was one of the exceptions, but like the Russian SST, never made any money, i.e operated at a loss).

The other big users of Gas Turbines (for that is what a Jet engine is) are helicopters, again expensive to operate and maintain, but liked in Helicopters for the engine are light and fuel efficient if operated at peak levels, which most are, the copter is either up in the air or on the ground NOT running). Hovering is good in a Helicopter, but even that tends to take almost all of the power of the engine (which was why the gyro-copter was so popular before WWII, simpler, more fuel efficient but needed a short runway to take off and land, much slower then a conventional plane but even today has a niche where he Gyro-copter is one of the more popular designs in the ultralights planes).

Just comment on why and how gas turbines are efficient. You just have to operate them at or near maximum speed to get that efficiency. A small gas turbine could provide all the power most people need in a hybrid when we remember the main purpose of an engine in a hybrid is to charge the batteries and for that purpose the gas turbine is ideal.