Small Turbojet Engines (Discussion)
Small Turbojet Engines (Discussion)
(OP)
Greetings.
I am in need of small, tubojet/fan engines for a preliminary aircraft design. I have noticed that there is a large void in the thrust output category, between 50 lbs thrust (model airplane turbines) and about 700 lbs thrust (Williams FJ22... as yet to be proven).
As of now, I have not found any jet engines within the 300 - 500 lb thrust range. Does anyone have any thoughts as to why we haven't brought jet engine technology down to even smaller levels?
Home experimenters have built turbine engines from such things as automotive turbo-chargers, and even the radio controlled industry has produced small turbine engines with 10 - 20 lbs of thrust...
Just a topic for discussion....
I am in need of small, tubojet/fan engines for a preliminary aircraft design. I have noticed that there is a large void in the thrust output category, between 50 lbs thrust (model airplane turbines) and about 700 lbs thrust (Williams FJ22... as yet to be proven).
As of now, I have not found any jet engines within the 300 - 500 lb thrust range. Does anyone have any thoughts as to why we haven't brought jet engine technology down to even smaller levels?
Home experimenters have built turbine engines from such things as automotive turbo-chargers, and even the radio controlled industry has produced small turbine engines with 10 - 20 lbs of thrust...
Just a topic for discussion....
Regards,
Grant Wittenborn
Aerospace Engineer
www.darcorp.com





RE: Small Turbojet Engines (Discussion)
NASA also has a very small program to study piston engine/ducted propeller combinations in terms of aircraft cost and design integration advantages, and several serious efforts are currently underway in this area.
RE: Small Turbojet Engines (Discussion)
1. Market need. An engine development program is a VERY expensive endeavor on any scale. There must be a need.
2. The problems that arise when dealing with small engines arise quite quickly. Going smaller is not an easy thing to do. One caveat to that is that one would want to reduce the overall engine size with the thrust output to keep it competetive in a commercial or military scenario. One could derate an existing engine to a lower thrust output, but you'd have a much worse thrust to weight ratio and SFC because of it.
Depending on what you need, you may find something if you look into target drone engines used by the military.
RE: Small Turbojet Engines (Discussion)
2. Very small engines are, indeed, difficult to design; and derating an existing engine leads to terrible inefficiencies due to the off-design operations. Nevertheless, if an on-purpose small turbofan is properly designed for the flight regime of today's faster piston engines, the efficiencies can be excellent.
Cruise missile and target drone engines are typically made for a very short life.
RE: Small Turbojet Engines (Discussion)
You can try these two:
http://www.agilis.com/engines.html
http://www.m-dot.com/page7.html
I don't know if either company has anything like a real "production" engine.
Good Luck.
Terry
RE: Small Turbojet Engines (Discussion)
Both are good leads. Agilis sounds the most promising of the two, as they contend that they will be ready to deliver small, 1,000 lb thrust engines but Q4 2004. 1,000 pounds of thrust currently seems to be the lower limit of thrust for production engines.
Regards,
Grant Wittenborn
Aerospace Engineer
www.darcorp.com
RE: Small Turbojet Engines (Discussion)