> are we sure that 3 seconds is the right time for a Saturn V on an E15?
Yeah, Roy -- from my experience with these models (and this motor), that
3 seconds is as close as one could get (in whole second increments).
The flight we did down at Kennedy in '94 used a -4 that I 'trimmed' to
(what I estimate as about) 2.8 to 2.9 seconds and it was absolutely
perfect timing. This was a beefed up Estes kit (with some 'payload': 10
commemorative documents, two patches and a sheet of Apollo 11 stamps -
about 2 ounces, total). With the additional thrust of those 4 mini A3-2
outboard motors, this should about counteract that 'commemorative
payload' -- such that a near-stock SatV and a single E15 would work out
about the same.
Nearly a decade of 'Challenger Commemorations' (that we do here) also
seems to confirm 3 seconds is far more accurate than 4. These flights
are rather 'plain jane' (no payload) and the timing still seems the
same. (Sure, a Saturn for Challenger doesn't exactly 'fit' -- but I just
haven't found time to do a 1/100 Shuttle (and modify the
pad/launcher/tower) -- :) One day. One day. "Pad A" for 'Saturn
configuration' -- "Pad B" for Shuttle -- that's the plan.)
It's somewhat an inertial thing here -- lighter models slow down quicker
- so the 'weight thing' (over a few ounces) seems to cancel out any
differences. A 20 ounce Saturn coasts about the same as a 16 (or 14)
YMMV - but mine didn't.