Originally posted by tedman
Has anybody brooken mach with a d21 if so how light would an md have to be to break mach.
Yes.
Back around 1990, Scott Pearce made a batch of White Lightning D21 (Tested out as D16) motors.
I built a rocket out of BT-20, the longest BT-20 plastic nose cone (I bought a bunch of Zinger kits) & G10 fins.
I tower launched it around midnight out at El Dorado Dry Lake outside of Las Vegas.
We had quite a crowd for the 'Speed Trials' with several folks showing up to fly rockets.
This was back before all these nifty onboard electronic payloads so velocity was determined using cameras and a slotted wheel spinning in front of the lens at a known rate of revolution.
We had to wait for the pictures to be developed before we could check the results. Scott crunched a lot of numbers and told me that my D21(D16) rocket had flown just barely over Mach 1.
Too bad my E45 and F55 models didn't show up very well in the pictures. My FSI Mach 1 kit did not ignite the second stage so I never found out if the kit would actually break Mach. The first stage did reach over 400 MPH.
The top speed at the event? Scott Pearce flying an AeroTech G300 with fins and nose cone glued to the motor casing. Tower launched, it reached a velocity of Mach 2.19.