Paul,
The major players are able to invest in R&D effort that is unaffordable by the model engine companies.

That wheel is from a Teledyne Continental 373-8C turbojet (940 Lbs of thrust, using 1980's technology). I was first introduced to this engine in around 1986.

I took the attached launch photo in 2001 at Kom Aushim AFB, (Egyptian Air Force) southwest of Cairo, Egypt.

The booster burns for 4.5 seconds, produces 4550Lbs (nominal) of thrust, when combined with the engine's 940 lbs of thrust, accelerates the UAV from zero airspeed to over 400 Kts at booster burnout and drop-off. The UAV weighs 2356 Lbs. gross.
When the booster ignites, it is Hellfire and Brimstone!!