That super hard balsa isn't good for planes. Get the good C-grain from Sig, or better yet, buy contest grade C-grain from specializedbalsa.com (my preferred supplier).
D engines would put this into F class, but would also shred it to bits at nearly 300 mph. So instead it's going to launch on a single D, or better yet an Aerotech E6 which will give almost 10 seconds of power at 80-100 mph and put this thing 500-600' up. I reckon some od my cheating ways should be acknowledged: I'm basing this setup off the Dynasoar Rocketry designs.