Is it better to stage shorter solid boosters like the flea or the hammer, or have longer solid boosters like the kickback.

[OrganicRobotics]

I've been wondering if staging boosters is the way to go because I've been having a bit of trouble getting into orbit without burning too much fuel. I'd like to get to orbit by the end of my second stage but I'm just short of enough power without using too much weight. If i remember correctly, in real life, they disconnect the empty rockets so that it isn't carrying around dead weight. Does this work in KSP too?

[Gargamel]

Moved to Gameplay Questions.

[Curveball Anders]

12 minutes ago, OrganicRobotics said:

 If i remember correctly, in real life, they disconnect the empty rockets so that it isn't carrying around dead weight. Does this work in KSP too?

It not only works, it's often essential.

 

[antipro]

26 minutes ago, OrganicRobotics said:

Does this work in KSP too?

of course it does, use decouplers. always decouple empty stuffs.
https://wiki.kerbalspaceprogram.com/wiki/Decoupler_and_separator#Decouplers

 

Quote

Is it better to stage shorter solid boosters like the flea or the hammer, or have longer solid boosters like the kickback.

there's not a fixed rule about that, it depends on how you've built your rocket.
usually hammers are a good compromise if you just need to orbit kerbin.
booster are cheap but have low Isp
https://wiki.kerbalspaceprogram.com/wiki/Specific_impulse
anyway if your rocket has too much low TWR you can add a pair of boosters.
can you provide a pic?

Edited December 20, 2020 by antipro

[bewing]

SRBs are super cheap, have lots of thrust, and work well in thick atmosphere. So they are the greatest thing you can have for the first part of your rocket.

If you can steer them properly, then longer-burning SRBs are almost always better. And steering them properly is generally pretty easy.

[MarsUltor]

11 minutes ago, bewing said:

And steering them properly is generally pretty easy.

To amend this statement... is generally pretty easy, as long as you have control surfaces to control your trajectory, otherwise, you’ll just keeping on accelerating in the direction you launched... reaction wheels can also be used to control your trajectory.

[Snark]

2 hours ago, OrganicRobotics said:

If i remember correctly, in real life, they disconnect the empty rockets so that it isn't carrying around dead weight. Does this work in KSP too?

Absolutely, and in fact it's usually vital to do so.

SRBs are great for boosting off the pad, but once they're burned out, they're just dead weight-- and a lot of it, too!  So definitely stage them away as soon as they burn out.

In general, the way to design multi-stage rockets is to discard each stage (engines and empty fuel tanks) as soon as it's burned out and no longer helping you move the ship.  It makes a world of difference.

[Wobbly Av8r]

After re-reading your question, I think what you're referring to is whether to stage SRB's (lots of Fleas vs. double Kickback).

First, because of the characteristics of SRB's, their primary use is First Stage optimized and staging ANY SRB for use other than lifting off of the surface is very inefficient although I'm sure someone can find the rare exception. This already precludes using a stack of Fleas in place of, say, a Kickback, even as you decouple them after burn out. And yes, ANY SRB needs to be dropped/staged ASAP after burnout - in terms of a clean separation, maybe even just an instant BEFORE burn out.

Because SRB's generally complement your liquid-fueled vessel, your choice of which type and/or how many is dependent on essentially two things:

1. How much payload you need to place in orbit; if your primary requirement is payload, use the largest SRB's that will cutout without shooting through your target orbital altitude. You will still need your On/Off property of your liquid-fuel engines to circularize your orbit.
2. How fast you need to accelerate your vessel in the Kerbin atmosphere; many larger rockets have significant "suction" drag at the base which rapidly decreases after achieving Mach 1 (~330 m/s, changes with altitude) - thus the quicker you accelerate past Mach 1 reduces the drag while conserving the amount of liquid fuel consumed down low and slow in Kerbin's atmosphere.

Edited December 20, 2020 by Wobbly Av8r
Reposted after re-reading question...

[Spricigo]

8 hours ago, MarsUltor said:

To amend this statement... is generally pretty easy, as long as you have control surfaces to control your trajectory, otherwise, you’ll just keeping on accelerating in the direction you launched... reaction wheels can also be used to control your trajectory.

Not really. With the right initial conditions, a well designed rocket it will be in a curved trajectory towards obit,  under the effect of thrust, weight and aerodynamic forces.  Control surfaces can be used to steer the rocket in those initial conditions but is not the only option.

 

11 hours ago, OrganicRobotics said:

I'd like to get to orbit by the end of my second stage but I'm just short of enough power without using too much weight.

A look at the craft would really help us to figure out what may be the problem.

 

[MarsUltor]

19 hours ago, Spricigo said:

With the right initial conditions, a well designed rocket...

This statement is a bit tone deaf, considering it appears that this guy seems new to the game, and is struggling to get into orbit; “the right initial conditions,” makes zero sense to somebody that is struggling to get into his first orbit... especially if he is ( I am assuming) playing career mode, where the launch clamps aren’t even until level 4.  And, unless you’re a savant, a new player is not going to know how to make a “well designed rocket.”

Edited December 21, 2020 by MarsUltor

[Empiro]

It sounds like the question is, should you use lots of small boosters and lots of stages, or one larger booster? Generally, the answer is "somewhere in the middle". Getting to orbit by the end of the 2nd stage is a pretty good goal. I typically use stage-and-a-half (liquid engine + detachable SRBs) designs to almost get into orbit. That way, the dropped stages crashes back into Kerbin.

The answer to your other question is yes, you should generally drop anything that is empty. Decouplers add mass, but they're very light compared to even the Flea. In career mode, I'll occasionally hold on to something like a Hammer for a little while, because an empty Hammer is fairly light and decouplers are pretty expensive.

[Spricigo]

1 hour ago, MarsUltor said:

This statement is a bit tone deaf, considering it appears that this guy seems new to the game, and is struggling to get into orbit;

Nope, he said the problem is the rocket becoming too big. 

1 hour ago, MarsUltor said:

“the right initial conditions,” makes zero sense to somebody...

If so,  somebody just need to ask for a clarification.

1 hour ago, MarsUltor said:

launch clamps aren’t even until level 4

Same deal for control surfaces.  But reactions wheels are available right from start with the Mk1 Command Pod.

 

2 hours ago, MarsUltor said:

 And, unless you’re a savant, a new player is not going to know how to make a “well designed rocket.”

Or rather, unless he  ask and get advice.  Which is exactly the objective of this forum section.