It wouldn't surprise me if the NEW subs had only one, just so nobody gets a propeller boo-boo 
This and a fire car thread had me looking back to the better days of my youth, and I thought of something that answers why my 175 rocket launcher hits the ceiling. And not just hits, but hits pretty hard. It was from a Mercury X-set and the original rocket had the capsule and parachute, it weighed a tad more, and didnt fly straight very well either (made in Korea? 
), so it must have needed the extra boost for the extra weight.
The platform icbm launch car was strong too and would tip the car over or.bounce it off the rails. Gramps put a different spring in that one to tame it.
Once the Mercury capsule was lost, the standard ICBM was all that I could get to replace it.
