Many years ago a buddy of mine used to fly his Maxi-Brute HoJo on a FSI conversion kit for F100 motors.
He was the only person I knew that had a good non-cato rate with the old F100.
I saw it fly at least 12 times successfully on the F100-6. Five of those flights happened in one day.
That thing really FLEW on those !
Flights on a D12-3 seemed like a DUD compared to that big BP motor.
I would imagine it would fly well on the Estes F15-6, but not nearly as extreme looking.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !