Preferred First Rocket Stage in Contracts Mode

[mythic_fci]

So basically, as the title says, what's your preferred first stage on lifters? Here's my opinion:

For very heavy lifters, liquid fuel wins out every time due to the sheer lifting power. But for light-medium launchers, surprisingly, solid rocket motors take the cake. They don't cost as much as equivalent liquid fuel boosters 90% of the time and are quite controllable with winglets and/or torque. Several of my crew transporters use SRMs to lift them into a suborbital trajectory, then use a liquid fuel second stage to boost into orbit. Usually, my SRM first stages are one "core" booster, with 2, 4, 6 or 8 side boosters strapped on. For lighter payloads, I ignite the side boosters first, then the main booster 5-10 seconds later so it can act as a "sustainer" engine to boost apoapsis a bit more.

[Strainborm]

The fact that SRB's are ridiculously cheap is their main benefit, in KSP career and in real life. In a lot of times I use just one single S1 SRB-KD25k (the new stock SRB, with thrust tweaked to just about 30% so I don't get TWR of like 10) as the first stage on lifters for small and medium payloads, and I don't feel guilty using those in bulk because it's so darn cheap. And I personally think that at least that SRB should cost quite a bit more than just 1800 credits. Sometimes I strap on the tiny RT-10 from underneath in stack if I need an extra kick

[Grover]

I compared a munar launch stage to see the cost difference between using SRBs and asparagus boosters, and becsuse much fewer parts were needed (two asparagus boosters gave as much DV as four medium SRBs) it only cost about Ó2k-Ó3k more to use liquid fuel, which is very agreeable given the increased level of control offered and the simpler construction required.

Asparagus all the way man!j

[Madrias]

Up until I started to get to an ability to make spaceplanes, I was using lots of solids. Still not up for Career SSTO yet, but I've stopped chucking SRB's everywhere now. I've switched to liquid fuel boosters as designs got more efficient, and then after that, I've switched to just plain old LF/O droptanks.

[Pecan]

Although I haven't put a lot of effort into career mode yet I'm mainly working on SSTO rockets and therefore liquid fuel. If it turns out to be cost-effective to use SRBs and just throw them away, without being too much more complex to build them, I'll give them a run.

[m00nchile]

Same here, I don't pay too much attention to cost effectiveness, so I go with liquid fuel, but if my lifter stage falls a bit short of achieving orbit, I'll strap on just enough SRBs to get a TWR of 1.2 with only SRBs firing, to get the first 2 or 3 km height before igniting my liquid fuel engines. I did just that when designing my Duna mission.

[Concentric]

I typically use hybrid first stages, with SRBs and a liquid core. Sometimes there's asparagus and/or droptanks, but I like the control of a liquid core and the low cost of the SRBs. My ultralight lifter (as in my disposable orbital rescue ship) is two of the Rockomax boosters, then an asparagus with two LV-T30/FL-T800 boosters feeding a LV-T45/FL-T800 core. That gets me my rendezvous and orbit matching with fuel to spare.

However, I have just managed to make a spaceplane that puts a small payload up, performs orbital rescue, and then flies back to the runway, so there may be a small shift coming in my playstyle. Perhaps just to orbital rescue and some probe missions.

Edited July 30, 2014 by Concentric

[SkyRender]

Given that the current iteration of the contracts system makes getting a steady influx of way too many Funds very easy, I don't even bother trying to design rockets to be especially affordable. I keep them efficient, mind, but cost is less an issue than my ability to effectively guide them to where I need them and get them to do what I need them to do.

[regex]

For light payloads (5~6 tons), I use a mostly-reusable lifter based around an orange tank and a Skipper plus a few throwaway SRBs. I use the SRBs to push the craft through the (idiocy of the) pea soup and then ignite the Skipper once they burn out. The turn happens shortly after SRB ejection so the Skipper is operating at a decent efficiency by that point.

For refueling interplanetary craft I have a fully reusable orange "fuel slug" plus integrated tug and control that gets lofted into orbit on top of a raft of huge SRBs. It is very tough to get into orbit, but the slug has enough delta-V for correction, rendezvous, and deorbit. This was mainly an exercise in how much I could put into orbit on SRBs alone (51 tons), and I'm sure others could do better.

E: I just realized I need to add "crash guards" to this one.

Aside from those, I usually build the lifter to the craft being put into space and it is generally completely disposable.

Edited July 30, 2014 by regex

[WWEdeadman]

Yeah, solid boosters are so cheap, I end up using them way more than I did before funds were a thing.

[Masetto]

The fuel efficiency of liquid-fuel engines increases A LOT after those first few thousand meters (except aerospikes of course).

Using SRBs to cover that early ground just makes too much sense to not do it.

Edited July 30, 2014 by Masetto

[NecroBones]

I had a thread about this last week: http://forum.kerbalspaceprogram.com/threads/87927-Budget-conscious-careers-Your-preference-Asparagus-or-Moar-Boosters

I started out switching to SRB-only lower stages, but then installed the StageRecovery mod after I posted about that. Now I'm back to mostly liquid-fuel lifters, with lots of parachutes.

But my SRB staging looked like this:

[Stargate525]

SRBs. As many as needed to get the first liquid fuel engine into an orbit for later capture and recovery. They're dirt cheap, and since Squad doesn't believe in part failure, their main RL drawback is essentially negated.

[Torquemadus]

I prefer to use a cluster of thrust limited SRBs as my first stage. A single decoupler and a few struts are enough to hold the cluster in place.

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[GigaG]

I've been using a central core made of a KS-25x4 cluster and 2 of the largest fuel tanks on top (with one smaller one on some payloads.) Usually, except on light payloads, this will be accompanied by 4 liquid rocket boosters in an asparagus configuration. I've recently begun experimenting with using 8 SRBs instead of 4 LRBs. I also tried 4 SRBs, but it doesn't quite leap off of the pad like it used to. Also, this experimentation results from trying out combinations due to unexplained rapid unplanned disassembly of the first stage (the fuel tank just above the main engine cluster) when the last set of boosters separated. At any rate, SRBs should be cheaper, although I do have 2 million in funds now, so cost is not a huge matter. If done properly, you can make orbit (or close to it) on this stage alone.

[User Unrelated]

I mean NASA is doing it, so why shouldn't I?

"Aw jus' stick 'er on top-a thu biggest solid yous got back 'dere!"

[MockKnizzle]

Liquid fueled with SRBs if necessary, essentially no different than if I was playing in Sandbox mode. Even with part costs, I've never even come close to running out of money.

[AeroAviation]

My first 2 stages are usually 4 SRB's for missions to kerbins moons or probe missions to Eve, Duna etc

[SRV Ron]

Low cost Mun Satellite orbiter.

Mun lander;

Interplanetary lander;

[zarakon]

I mean NASA is doing it, so why shouldn't I?

"Aw jus' stick 'er on top-a thu biggest solid yous got back 'dere!"

http://constellationprogram.com/startpage/ESAS_Lunar/ILC_Launch.1k3.jpg

This design does not work at all in KSP

[biohazard15]

This design does not work at all in KSP

It works flawlessly, you just need a powerful SRB from mods (NovaPunch Advanced SRB and K-2X allows you to recreate Ares I fairly accurate).

[LethalDose]

Liquid fueled core with strap-on SRBs. The SRBs are just there to give the rocket a "running start", and then I have the versatility of the LF engines to throttle up/down/off as I need to get the payload into the correct orbit. Works great.

I'm not bothering with making anything reusable. I tried putting radial chutes on my LF lifter once. once. DER just chewed'em up and I had to watch that stage crash into the ocean.

[Monger]

For lighter rockets, an SRB-only first stage is perfectly okay. The more complex the ships get, the more I am missing that SRBs have no gimballing. RCS won't suffice, so I need small liquid engines to hold the rocket on course. However, they are unlocked quite late in the tech tree.

I'm not bothering with making anything reusable. I tried putting radial chutes on my LF lifter once. once. DER just chewed'em up and I had to watch that stage crash into the ocean.

You need to deploy them a lot earlier before they unfold. They need to significantly slow down the craft (below 100ms/s) so you won't take any damage.

[Yarrula]

Stayputnik for scale (can't start with a sub-assembly)

This SRB only first stage has lifted almost every mission of mine. I tweak the thrust between 67 to 75, depending on the weight of what I'm trying to throw. It usually burns out somewhere around 15,000 and well over sane terminal velocity. The liquid second stage takes over from there to make the AP at the desired height.

[Bean]

Interesting, so far no one has mentioned jets.

I use a just first stage with a Liquid booster for circularisation, I bring the launch vehicle back to the runway once the payload is in orbit.

For small missions (Mun, Minmus, satellites) I have a small SSTO Jet+Rocket. Powered landing on jets is tricky, I tend to use the jets to reduce below 10m/s then use a burst of the rocket just before touch down to cushion the landing.

Hurrah for 100% recovery.

My Duna mission with 12 satellites and 2 landers has an SSTO Launcher, jets are pretty great right now.