How many boosters do you use (if any)?

[Vectura]

So there seems to be primarily 3 methods of boosting rockets in the real world-

1. No boosters at all, with a powerful core stage (eg, saturn V)
2. A pair of large, powerful boosters, with a similarly powerful core stage (eg falcon heavy, ariane 5)
3. A large number of smaller boosters, often with a variable number depending on requirements (eg energia, delta III)

I personally tend to use a single powerful main stack, only resorting to a pair of boosters if there isn't a core engine strong enough. I imagine having several smaller boosters would allow you to create a single lifter with a wide payload range, by simply varying the number of boosters, but I tend to build my lifters custom for each payload.

What do you usually do?

Edited March 9, 2020 by Vectura

[Mikenike]

Just now, Vectura said:

So there seems to be primarily 3 methods of boosting rockets in the real world-

1. No boosters at all, with a powerful core stage (eg, saturn V)
2. A pair of large, powerful boosters, with a similarly powerful core stage (eg falcon 9 heavy, ariane 5)
3. A large number of smaller boosters, often with a variable number depending on requirements (eg energia, delta III)

I personally tend to use a single powerful main stack, only resorting to a pair of boosters if there isn't a core engine strong enough. I imagine having several smaller boosters would allow you to create a single lifter with a wide payload range, by simply varying the number of boosters, but I tend to build my lifters custom for each payload.

What do you usually do?

I normally do about the same, in part because I suck at ensuring that the boosters are secure, so I try and use a single stack that is powerful. I also custom build the launch vehicle to fit specific roles, I have and will never try and use an adaptable booster system, I.e the Delta 3 platform, or Soyuz and Falcon 9.

[adsii1970]

It depends on the weight of what I'm putting into orbit. With the shuttle I have, depending on the load, I have a two-SRB and a four-SRB version. 

36 minutes ago, Mikenike said:

I normally do about the same, in part because I suck at ensuring that the boosters are secure, so I try and use a single stack that is powerful. I also custom build the launch vehicle to fit specific roles, I have and will never try and use an adaptable booster system, I.e the Delta 3 platform, or Soyuz and Falcon 9.

Use the struts. Strut the SRBs/booster to whatever your main lifting stack is. When using decouplers, the struts will "break" when you activate the radial decouplers. 

This allows the boosters remain rigid and pointing in the right direction when in use. And it allows the booster to be dropped when it's fuel is expended.

[steuben]

- What do you mean, how many boosters?
- <eye buggy scream>All! Of! Them!</eye buggy scream>

*cough*

But, it tends to be 2 to 8 boosters, asparagused together, around a core. Everything tends to have the same engine. The core will sometimes be much weaker depending on what I'm lifting.

Mental note: design a single booster rocket.

Edited March 9, 2020 by steuben

[Bej Kerman]

52 minutes ago, Vectura said:

eg falcon 9 heavy

Either 9 or heavy.

[Vectura]

Corrected, thanks

[Dirkidirk]

depends on the size of the payload: either one large core booster, one large core booster with two equally sized boosters on each side, a core with a bunch of appropriately sized boosters, or what I call, "LAG SUPREME".

boosters on boosters on boosters, with asparagus staging and all 3.75 meters and a single 5 meter core. AND DON'T THINK THE SECOND OR THIRD STAGE ARE GOING UNSCAVED. I NEED EVERY OUNCE of that Delta-V and a thrust to weight ratio higher than 2 so it doesn't take 2 hours to get into orbit!

[Guest]

If I'm playing a frugal bare-bones career, I use twin boosters on most of my early-career rockets. 

After I get better tech I switch to reusable SSTOs, which counts as "other" I think.

[RealKerbal3x]

I tend to add 2-4 boosters, test the rocket, and then realise that I have a wasteful amount of excess delta-V and remove them.

[wumpus]

Especially before the "moar boosters" pack, I'd often build larger rockets with multiple kickback stages.  I also remember that was the favorite strategy for low cost to orbit with expendable boosters (a forum competition).

One strategy I used for a long time was to have a pair of boosters to one side, and connect all other boosters to that stage.  This was more important with hammers (and somewhat with thumpers) as the cost of the decouplers was often more than the booster.  With the current options, it makes more sense to go simply use larger engines (and even more huge boosters) rather than adding more boosters.

[Curveball Anders]

I usually go with 4 SRB's. tweaked so they drop at around 20, just when the core is powering back up after Max Q.

 

[DStaal]

Typically either a single core, or if I can't get enough dV on the core (without dropping the TWR to low) I'll add 3-4 SRBs.  The SRBs will be in a separate stage, and drop before the core fires up.  Occasionally for really heavy payloads where I need both dV and TWR, I'll do the same 3-4, but as LFO and staged to the main stage.

I've played with Asparagus staging a few times, but I rarely need to get that exotic.

[Vanamonde]

Zero, two, or four. More than that and they start to bang into things as they're ejected. 

[DeadJohn]

I prefer to use a single powerful core, adding boosters when I need extra TWR or DV for heavier loads and more distant missions. Early in the game, I just cobble rockets together using whatever parts are unlocked. It's not uncommon to resort to "moar boosters" to reach orbit.

Things change later in the game. After I have more parts unlocked, and have run several successful missions using the same basic design, I turn that into a permanent "lifter". The lifters usually have a fairing on top. I fill the fairing with ore and test how much mass can safely reach low orbit, then note the capacity.

When planning a new mission, I design the payload first, then design a transfer stage to get it from LKO to its destination. Once I know the mass of the payload+transfer I can select an already designed lifter. That process offers several benefits:

1. It speeds up the design of new missions because half the work is already done for me. I design the payload+transfer and stages 1+2 are already done. This ultimately doesn't actually save me time but instead lets me put even more effort into the payload design.
2. It's easier to do an efficient gravity turn because I've practiced with that lifter before. I know how soon and how sharp to turn.
3. This is similar to how real space launches are done. I find I enjoy that aspect, and as I unlock new tech I can upgrade a lifter or design a new lifter from scratch.

 

[sturmhauke]

7 hours ago, Mikenike said:

I normally do about the same, in part because I suck at ensuring that the boosters are secure, so I try and use a single stack that is powerful.

I build my rockets like this. Done correctly, the boosters will naturally pitch outward and away from your rocket after staging, due to aero forces.

strapon booster |>]=============*=============
                     |           ][ decoupler \
core stage        |\]#################################
                  |/]#################################
               strut |           ][           / strut
strapon booster |>]=============*=============
                            booster CoM

[James M]

I like to only use a single core or two solid boosters unless my payload is over like 50 tons. After that its Asparagus staging two LF/OX boosters. I limit myself to two because to me if it takes more than that to get to orbit, it means I'm doing something wrong. Too much drag or too much unnecessary payload weight. If it's issue number two, I generally use my stock standard reusable single booster to deliver separate connecting payloads.

[jimmymcgoochie]

I usually go for a fairly small central stack with boosters on the outsides. The SRBs provide the extra oomph to get it off the launchpad and usually also have extra fuel tanks on top to boost its range/payload capacity, and the main stack can use a smaller but lighter/more efficient engine which makes it cheaper and gives it more delta-V once in orbit. When paired with something like Stage Recovery to salvage the SRBs it can reduce launch costs considerably over using one big stack. I don't use LF/Ox powered side boosters often, but they fill a similar niche.

Big stacks need bigger engines, which tend to be less efficient, and the extra mass of engine and fuel tank plus the fact that it has to be carried until the stage is empty will reduce your payload capacity; however a single stack has the advantage of a smaller aerodynamic profile, less complicated staging and you don't generally have to throw struts around to keep the thing from shaking/tearing/wobbling itself apart 3 seconds after launch.

[KerballingSmasher]

Well, it depends on the size/destination of the payload. Sometimes, I'll use no boosters if it's a standard Kerbin system mission. If it's interplanetary, maybe use a larger launch vehicle or about four boosters. If it's really heavy, maayyyyybe six.

 

Oh, and if it doesn't work, then I may even go up to about ten boosters XD

Edited March 10, 2020 by Kerballing (Got Dunked On)

[LittleBitMore]

I do something interesting: 2.5m core stage with the Skipper (Mainsail if heavy loads), and 6 radially attached asparagus staged Making History Soyuz boosters with a Skiff or something underneath them. My most efficient mid-size launcher.

[Rocket Witch]

All of the above?

Initially I design a boosterless core for a particular set of requirements. As requirements and technology change I produce variants on the craft which may be boosted. Sometimes these variants do just have sets of 0.625m to 1.875m strap-on SRBs, particularly in the case of smaller rockets launching routine items like satellites and resupplies.

But often my go-to is a pair of common core boosters with a downthrottled core — I'm not into onion or asparagus staging for realism and to avoid TWR issues. I've found this to be the easiest layout to design (just copypasta the core — that's alt+click if you didn't know!) and fly (good rear-end body lift ratio to counteract the added rear-end mass). If I did a 4xCCB rocket I would actually put the boosters on the outside of the original 2, rather than using 4-way symmetry, giving it a 'middle finger' appearance. This is to avoid separation issues with the 'top' booster as the rocket turns over, and maintain the lifitng body effect for stability. Over the past year, my design philosophy has been increasingly based on rows of engines rather than rings, as I really find that 'aircraft mimicry' has a positive effect on reliability.

I also like to use solid rocket 'boosters' as cores instead, like the Ares I and Saturn INT-05. These tend to be quite hard to fly even with gimballing, but there's something appealing about the raw simplicity.

Edited March 11, 2020 by Rocket Witch

[DoubleAACE]

I have been known to use staged boosters. I'm a big fan of doing a semi-vacuum optimized core with sea level optimized boosters though. If staged, these boosters will have a vacuum optimized upper stage.

[Superfluous J]

I use the correct number of boosters.

That number varies based on the ship I'm building and is generally an even number between 0-6 inclusive. Very very rarely I'll do 3 but I usually regret that.

Edited March 12, 2020 by 5thHorseman

[VoidSquid]

Up to 60 Kickbacks on one of my 1.7.3 vessels.

1st stage usually consists only of SRBs with 1200-1300 m/s, up to 10-12 km altitude, reaching a vertical speed of some 400 m/s.

Edited March 12, 2020 by VoidSquid

[CBase]

Thanks to SpaceY Extended my first stages are all SSTO without SRB. The first stage might include multiple tubes, but it would still stay until return from orbit in the same configuration.

[Ogberi]

Quite simple. Moar.