Rocket Design Question

[jdsutton]

I'm trying to cut down on the bulk of my rocket designs and build a more realistic-looking rocket. So far most of my rockets use asparagus staging and mainsails to do most of the lifting. Is is feasible to use several smaller engines with higher ISP in place of a single large engine? Will the added weight negate the benefits of high ISP? Do I have to use mods to create a rocket that works well with a semi-realistic design?

[Vanamonde]

Using multiple smaller engines is a common KSP practice, and the weight tradeoff depends on the particular engines involved. Remember, though, that mounting multiple engines will require additional parts and their mass, such as this tricoupler arrangement.

[Teirusu]

Typically, as long as the mass of the extra hardware and engines is not a significant percentage of your payload mass, (Which it usually isn't if your making a 2.5m rocket) then you do gain a bit more Delta-V by clustering the smaller, higher ISP engines instead of using the Mainsail. The trick is, however, being able to cluster enough motors to equal, or better, the power of the Mainsail on the bottom of a 2.5m tank.

If you're wanting to stay stock many people use the tiny cubic-struts on the bottom of the tank, or the BZ-52 Radial Attachment point, and then there's the bi/tri-couplers as well.

If you're willing to try out mods, then there's my cluster mount parts. Link my in signature.

[SRV Ron]

I did just that to get a better balance on one of my designs using a trick, the tiny cubes, to mount four LV-30 under the Rockomax fuel tank for each of the six boosters on the onion design and four LV 45 on the center second stage. Performance was so much improved that I got the second stage into Mun orbit with fuel to spare. On that rocker, Mainsails were too much thrust and Skippers not enough thrust for launch efficiency. Disadvantage is that you will get frame rate issues from having four times as many engines firing upon launch, in my case, 28 of them. You will also need separatrons on top of the boosters to protect the second stage from separation damage to the engines.

Edited July 14, 2013 by SRV Ron