l always urge extreme caution when people suggest using an E9 in place of a D12. To be fair, you never said you were thinking of an E9 as you may be thinking of an Aerotech E. However, as NAR2996 has stated, the E9 produces less avergae thrust thean the D12. More than a few people have crashed some very nice rockets when substituting the E9 for the D12. Don't get me wrong, the E9 is a favorite motor of mine, but it must be used in light rockets. The Semroc Satrun 1B is to big and draggy for the E9 in my opinion.
NAR# 92125 L1
Total Impulse for 2011: 1,729 N/s
Total Impulse for 2012: 1,689 N/s
Total Impulse for 2013: 795 N/s
A:6, B:5, C:19 D:15, E:4 F:0, G:0, H:1, I:0