From back in 2000, this is my friend Anish and I trying to break Mach 1.0 with a model rocket (class G engine - under the limit for special permits). We did not succeed, but it did reach approximately 609 miles per hour (Mach 0.79). Launch weight was about 500 grams total, 250 g of that was the engine, an Aerotech G80, smokeless. Initial acceleration was about 30 G's. Burn time about 1.5 seconds. 2900 feet altitude at streamer deployment. Air drag at engine burn-out was about 10G's of deceleration. All of this was measured with a homemade on-board acceleration data logger.