These were a mix of older German and more recent Chinese made Quest engines. (The German made engines have "silver" nozzles, the Chinese engines have light tan clay nozzles.)
I've just finished two Estes Guardian models.
I loaded a Guardian with a Chinese B6-4 engine. The engine seemed to slide too far forward. There was almost a 1/8" gap between the low end of the engine and the lower bend of the engine hook.
I measured the engine, it was 3/32" short of the standard 2 3/4" length.
Could this be a problem? Maybe.
During boost the engine is forward against the front bend of the hook and engine block.
At ejection the engine casing could kick back and hit the low end of the engine hook. This might tear the upper notch in the BT-20 engine mount tube.
I'll do a bit of friction fitting with masking tape so the engine won't move.
If you've read my flight comments, you know I like the Quest B6-4 engines. They are loud, sooty and can out perform the Estes B6-4 engines. The ejection charges are weaker but in a smaller body tube they will blow out a carefully packed parachute.
The Quest C6 engines are not as strong as the Estes C6. They perform best in minimum diameter models.
The solution is simple: Sand an AR-520 down to the thickness needed to compensate for the engine's shortness and put it in the motor mount first. Just remember to remove it when you use an Estes motor.
ReplyDeleteYep, that'd do it!
ReplyDeleteI wrote this post wondering if there were any thin engine mount tubes torn by the top of the engine hook being kicked back at ejection. There is some "play" in the fit of these engines.