How long your first stages last?

[Xemina]

About 15-20 km, sometimes to orbit (80-90 km)

[DrLicor]

It really depends. I to build my rockets 2,5 stages. So a first stage with boosters. Normally the first stage burns for 3 to 5 minutes. With the boosters helping the first minutes untill the TWR of the main engines is strong enough.

[NSEP]

12 hours ago, kerbinorbiter said:

whats the point in having a stage to 1km?

An alternative for a booster.

Maybe the first stage can destroy the bad you know so you just boost it up high and let it do its job.

[kerbinorbiter]

usually my stages last until 100km then i drop them and if fuel is good i recover 'em!

I don't really use solids, but when i do someone gets mad  

Edited July 30, 2017 by kerbinorbiter

[Mastikator]

I like my first stage to be a big grid of short boosters to give me an initial kick, so very very early. The second stage mostly keeps the course at first and then at around the 10km mark I might get red flame effects.

[TheKSPBeginner]

All the way to Kerbosynchronus Orbit. The second stage is detached from the two satellites, still full of fuel.

[Just Jim]

I use asparagus set-up mostly... so technically my first stages usually make it to orbit... My first asparagus boosters, however... I'm lucky if the first ones don't fall back onto my launch pad! 

[Jetski]

First stage drops at 6000m

Seriously though, for Kerbin takeoffs, I generally use SRBs attached radially to the end of a wing.  Slap an LFO tank on top, enable crossfeed, and your first core stage reaches 40km still full of fuel.  Also the wings keep the boosters far enough away from the core to avoid the need for Seperatrons.  Decouplers can go at either end of the wing, depending if you want to still have fins on the core after decoupling.  So first stage drop is just SRB/droptanks, and between 30 and 50 km.

Edited July 30, 2017 by Jetski

[suicidejunkie]

200-300m for most.  Like Mastikator, I like to use a high velocity launch pad made out of Hammers.

That, or the first stage lasts approx 200Mm and returns for the full refund.

[DunaManiac]

Mine usually get me close to orbit or into orbit. (1900 m/s - 2200 m/s)

[Spaceman17]

well, in SLS i got a Meco almost in orbit, so the first stage separates at 80 km, then the 2nd stage burns to get into orbit

[RoadRunnerAerospace]

I have done it! My booster got me into orbit for once!

[GDJ]

Usually around 40 - 43 km before booster burnout, based on the simplest launch vehicle known to Kerbalkind (  )

[Freds]

I have a series of launchers in my subassembly library that i use for common launches.
Most are 2 stages, with the same design rules: The first stage stops burning at 35/45km, with enough speed to raise the apoapsis to 80/90Km. Then the second stage kicks in, putting the cargo into orbit( most of the time ).
The 1st stage returns to kerbin with parachutes (i use stage recovery mod), the second stage, sometimes stays in orbit, sometimes burns into atmosphere... depends on the weight of the cargo.

The 1st stage are a mix of LF/OX + SRB + wing attached to the the bottom part of SRB for extra stability.

The SRB Thrust are adjusted to stop burning a few seconds (5 - 10 )before the rocket fuel ends - i prefer this kind of design because it dont need to stage SRB radial decoupling, and the extra node helps in the placements of the return parachutes.

The 2nd stage are simple: Just an engine, a fuel tank, a procedural fairing and a decoupler. If the stage is based on 3,5M (or bigger) parts, it has 4 vernor attached ao allow vessel orientation.
 

[invision]

not including boosters i usually get to full orbit first stage

boosters fall off about 12,000m if im using them

[Curveball Anders]

On 2017-07-29 at 7:13 PM, Laie said:

How long is a piece of string?

- Twice as long as half a piece of string.

- Half as long as the average length of two pieces of string divided by two.

[Jouni]

When I use serial staging, 50-60% of launch mass is propellant for the first stage. Because I prefer launching with a low initial TWR, maybe 1.2 to 1.3, and because the sea level Isp of the appropriate engines is slightly below 300 s, the first stage lasts for 120-150 seconds. This produces 2000-2700 m/s. The staging altitude depends greatly on the propellant mass fraction, the intended orbit, and the TWR of the second stage.

If I use boosters, the core stage lasts for 3-4 minutes, which is often enough to reach orbit.

[John FX]

I like my first stage to get me to the point that I could use an Ion engine to circularise.

[StupidAndy]

i can get my asparagus staging rockets to go to orbit, but i don't want them to go to orbit, so it isn't all that goodly

[Bottle Rocketeer 500]

My SLS's first stage has about 1/6 of its fuel left when I jettison it once I get out of the atmosphere.

[wumpus]

On 7/29/2017 at 7:20 PM, kerbinorbiter said:

whats the point in having a stage to 1km?

I'm sure I've done it by attaching a Thumper (probably a cluster of them).  A thumper is 400 roots and radial decouplers start at 600 (and you need at least two), so stuffing thumpers vertically under a rocket makes sense.  The real point of the delta-v is to get going out of the atmosphere, not so much getting the total delta-v needed to orbit.  

You really don't want to know how much fuel Apollo (TWR@launch~1.15) used up before 1km (note that I'm not sure the gains are all that much, see the recent Scott Manley air launch video.  But it feels a lot better to watch your rocket *move* than churn through its fuel <1km.  If not for the relative cost of radial decouplers, I'd strongly prefer a booster/sustainer use (which work great with kickers)).

Back when the physics bubble was smaller, I was experimenting with <1km first stages (likely asparagas stages).  Some of them even had SRBs (fleas?) to fire down and land before the physics bubble left, but I think that parachute behavior had already become more realistic and the "last minute chute" strategy woudln't work anymore.  Nothing ever became of it, but it was one of those weird things that KSP calculation kludges would encourage (like pancake rockets).

I wonder if lithobraking strategies would work on low-alltitude recoverable first stages...

PS: to get back on some less mad rocket science, a great rule of thumb is to have equal delta-v for each stage (another is to double the mass of each stage).  I think this type of basic thing needs to be mentioned more on KSP forums.

Edited August 4, 2017 by wumpus

[Leafbaron]

Typically until they burn out  But in all seriousness, I have been running space plane only careers for sometime now, so my first stage takes me all the way to orbit. 

However, when I do use rockets, it depends on the payload. If the payload is aerodynamic and upper stage is stable I will have them last to about 15-20km then stage to a more efficient engine but if the payload is unstable Ill make sure the first stage gets me to at least 30km. 

Edited August 4, 2017 by Leafbaron

[fourfa]

With disposable lifters - I aim to use a single sustainer core, firing from launch all the way until setting a 80km apoapsis.  Payload does its own circularization (always less than 100m/s burn because proper gravity turn, or should I say proper GravityTurn), so the core stage will leave no space trash.  Core fuel load should be such that TWR without SRBs is about 1.0 on the pad.  Add radial SRBs as needed to get total launcher dV to ~3200m/s, adjust SRB thrust downward for 1.5TWR on the pad.  

Early career it's 1.25m Swivel cores, then Skipper, then I make heavy use of the Twin Boar for a long, long time in mid-late career while costs still matter. Once money starts to accumulate, anything goes.

Now, for an ordinary stock career, I'd add just a bit of dV to get the core to SSTO, then deorbit and parachute to recovery in the water near the KSC.  My last few careers I won't use the Recover button unless on the runway or launchpad, and building big ships to tow core stages home is not really worth the bother.

Edited August 4, 2017 by fourfa

[suicidejunkie]

On 8/4/2017 at 2:55 PM, wumpus said:

I'm sure I've done it by attaching a Thumper (probably a cluster of them).  A thumper is 400 roots and radial decouplers start at 600 (and you need at least two), so stuffing thumpers vertically under a rocket makes sense.  The real point of the delta-v is to get going out of the atmosphere, not so much getting the total delta-v needed to orbit.  

You really don't want to know how much fuel Apollo (TWR@launch~1.15) used up before 1km (note that I'm not sure the gains are all that much, see the recent Scott Manley air launch video.  But it feels a lot better to watch your rocket *move* than churn through its fuel <1km.  If not for the relative cost of radial decouplers, I'd strongly prefer a booster/sustainer use (which work great with kickers)).

You don't need the radial decouplers unless you're planning to have multiple solid stages, and solids are heavy enough that you shouldn't try to lift one off the ground unless it is burning.

Just bolt the SRBs together for free and drop them all at once with a single stack decoupler.  Steer heavier rockets gently to prevent origami around that single connection point.

[ZooNamedGames]

My rockets generally burn out at around 20-25km which is very realistic to real rocket separations. Especially rockets like the Saturn V.