Originally Posted by Carl@Semroc

This is some of the best news for model rocketry in a while! Congratulations to the engine gurus at Estes for this accomplishment. They are essentially a "bring back" of the Centuri Mini-Max "EB" engines from 1971. I never got a chance to fly those because it happened just after Semroc went insolvent and I was starting a career in electronics.

They are very close to these Mini-Max engines in specifications and probably even closer to the actual delivered performance. Granted, they are not the port burning for high lift, but they do fill a need and will be a lot of fun to watch.

The slow ramp up and low peak thrust will present challenges for heavier rockets, but they ARE mid-power engines and most mid-power rockets are flown off rods longer than 3 feet. I agree with John that the biggest problem will be finding the rockets.

NOW we can finally do a two-stage SLS Firefly!