E engine in a Semroc Saturn 1B?
 

First post here--I purchased a Semroc Saturn 1B kit last year (had one from Estes in 1978) and goofed up the motor mount. Semroc sent me a new engine retainer, which I installed. I didn't realize the retainer is 3 3/4 inches long until I put a D 12-3 engine in, and it kept going! Can this model fly safely on an E engine?
Thanks!
Paul

I don't know the answer to your question, but if not you could always stick in a 1" spacer ahead of a 'D' engine.

Joe

SEMROC doesn't show an E as a recommended motor. It does however show a cluster of four C's that would make an E impulse (two Cs = D, two Ds = E). As long as the E doesn't weigh more than the four C's and it meets the minimum liftoff weight, it should fly.

I would NOT try flying any heavy 4" diameter rocket on an anemic low average thrust Estes SU BP E9....it will not fly safely.
If you want to try an "E" get an RMS24 with an E18W or E28T reload.
A 4xC6-5 cluster is the equivalent of a 36 n-sec E24, and Estes E9 is only 28 n-sec (not even equal to a full 20 n-sec D and a full 10 n-sec C put together) with a very low average thrust.

A D12 will barely fly it but an E9 won't with any reasonable length launch rod (under 8 feet).

Don't risk a nicely built complex kit such as the Semroc S1B on a wimpy Estes E9.

If you doubt this, send an email to Carl at Semroc; I'd bet his answer is the same as mine....DON'T USE AN E9.

I am quite experienced in the hobby, but have no experience with this bird, so value this swag in that light.

If you want to use E motors, I would use an Aerotech E18 or similar - something with a little more kick off the rod.

Doug



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I think the max thrust of four C6-3's is considerably higher than the max thrust of a single E9. I'll have to check, to make sure. IIRC, the E9's max thrust is about 10N less than a D12.

Ok....just got back from the NAR test data web page....

C6-3 peak thrust 14.09N Four of them would be a bit over 56N peak thrust.

The E9-4 only has a peak thrust of 19.47N.......way under half of a four C6 cluster.


Just for the info, a D12-3 peaks at 29.73N...hey, at least I did remember it was about 10N more than the E9. My memory isn't completely gone. ;)

Thanks for the info!
Paul

I would not try it! I did try an SLS Laser-X once on a single E9 and it was VERY sluggish, almost unsafe. It is two ounces lighter than a Saturn 1B. Rocksim says a Saturn needs a 10 foot rod to reach 30MPH with an E9!

dont do it dood.

Better bet--use that 1" spacer recommended earlier, but slip an F12 behind it, not a D12. Lots of smoke, and much more enjoyable flight.

E9 would only be an option if you have a good shovel and are looking for an excuse to build another one after the learning experience from building this one.