Benefit of Solid Rockets over Liquid

[spyker92]

Solid fuel is best used for sheer power in atmosphere. A very good design combined with asparagus launchers and winglets can get 50T anywhere from 50,000km - 80,000km sub-orbit. (lower quality launchers can easily reach 10k or 20k) At which point you just switch to liquid fuel and complete the turn. And plus those smoke plums are just sexy.

[SDIR]

Solid fuel is nice for small craft. Get any larger and you need too many of them. And about the topic on asparagas, I find that even if you don't use asparagas or crossfeeding liquids get you higher.

[Temstar]

You can have liquid fuel tanks on top of SRBs feeding liquid engines so that at the moment of SRB separation you still have all the liquid tanks fully fuelled. You just can't asparagus stage solids in pairs.

[ComradeGoat]

Fuelled boosters in asparagus format get more fuel into orbit than using SRBs I've found though.

And sorting out the staging with asparagus rockets with SRBs is annoying.

[SDIR]

And sorting out the staging with asparagus rockets with SRBs is annoying.

Not if you have no more than 3 pairs. Anymore, then yes, but asparagas is much more efficient, even though it is a bit unrealistic in real life.

[NeoMorph]

Hold on... you can't asparagus SRBs properly because they don't feed momma. The whole beauty of asparagus is that you get to top up the momma tank while peeling off the dead weight empty tanks.

One thing though... I never go beyond using four asparagus tanks because any more tends to look fugly. I like to make my rockets somewhat believable (which means shrouds over ugly un-aerodynamic payloads) and no umpteen million tanks like some people do.

[Ben314]

I used to use SRBs back when I had just the demo, as my first three stages (tri coupler connected to three tri couplers connected to 9 tri couplers, then three stages of SRBs), because they were the only way to get power and throttling wasn't necessary (or so I thought). Now I just find they lower your overall dV or only marginally increase it, their only use is getting rockets that are wayyyy too big off the ground. Like everyone says on this thread, asparagus staging is better -as long as cost is not an issue-.

[Bunzmaster]

Are you sticking the mainsails at the bottom of an orange tank? Those tend to make every engine overheat a lot faster. If you stick the smallest 2.5m tank (X200-16 I think) at the bottom of your orange tank, you have a tiny bit more fuel, not much more weight and it completely removes the overheating bug of the orange tanks. You could throttle up a mainsail to full throttle and let it burn till fuel out and it STILL wouldn't overheat. It's very useful in situations like yours, where you need to throttle down but that throws your TWR off.

The classical stock asparagus design is two orange tanks with one small X200-16 the bottom and a mainsail as the core stage and three pairs of identical boosters on the side. You should get over 70t in orbit with that easily.

That's extremely good info. Thanks!

Well my rig got my lander to the Mun and I made my first landing. Now I just have to get home again.

Edited June 11, 2013 by Bunzmaster

[CatastrophicFailure]

I like em just for the challenge of working with them. Try making a rocket with ONLY solids some time, that can put a Kerbal into a stable orbit AND de orbit him again. Then try going to the Mün.

[FlamedSteak]

Asparagus staging has it's place, but when you need raw thrust to get a big load into orbit, solid boosters are the best way to get your load up to 100kmh @ 10,000

[automcdonough]

i like launching lightweight probe craft with 1 liquid stage with a few solids slapped on. very simple rocket that gets way up there.

[Zephram Kerman]

SRBs are most useful for the first few moments of launch. Remember the optimum ascent is to keep your rocket at terminal velocity. At sea level on Kerbin, that's 104 m/s. But if your liquid fuel rocket can accelerate from 0 to 104 in 5 seconds, it's overpowered. You'll then have to throttle back too much for the remainder of that stage, which means carrying extra engines as dead weight. So jettison those engines, which means SRBs.

[BubbaWilkins]

SRB's keep the early stage TWR reasonable while at the same time keeping the parts counts down.

Otherwise, building this monster would have such a high parts count and low thrust that it wouldn't make orbit even without a payload.

Edited June 10, 2013 by BubbaWilkins

[Guest]

To definatly make sure you don't use liquid fuel you're transporting to avoid balancing issues, they're also cheap.

[asmi]

I use them when my mainline LV can't lift the payload I want it too. Kinda like Atlas-V design - base core does most of the work, but for more heavy payloads it's TWR get dangerously close to 1, so I use SRBs to get it rolling. By the time of SRB burnout, TWR is sufficiently above 1 to complete ascent.

I don't like building new rockets for each and every launch, so I have a number of "base" LVs for different payload classes and various fairing sizes handy in Subassembly, in case it's neccesary I augment them with SRBs (usually two to four are enough). This approach have a benefit of having a fleet of flight-tested LVs ready to do what you need it to, and also I know optimal ascent profiles for each of them, which ensures success (I play with FAR, so maintaining optimal trajectory is important to ensure rocket doesn't tip over).

[Startreader]

I found out the other day that if you strap enough SRBS behind a probe, you get a interplanetary probe