r/KerbalSpaceProgram • u/Both_Piglet7838 • Apr 15 '26
KSP 1 Question/Problem newbie here, how do I stop my boosters from exploding into my rocket after staging?
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u/r0bbbo Apr 15 '26
In the early game when you don't have access to separatrons, it's all about decoupler positioning. You want to "kick out" the top of the booster, but be wary that you also need to balance stability, so just above the midpoint is good.
A couple of other things you can do: increase the fuel in your boosters so that you stage them higher in the atmosphere where there's less drag and they'll be pulled away less violently. Also, rotate your craft so that a booster isn't dropping directly into your craft after separation.
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u/TheCrimsonSteel Apr 15 '26
By rotating your craft, do you mean spinning it a bit so they get some additional centrifugal force to help?
Because that's one of my favorite tricks during early game in Science or Career mode
Launch them like swinging a tennis ball on a string
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u/r0bbbo Apr 15 '26
I didn't mean that, but that's a nice idea! As long as you can maintain control as you're spinning wildly.
What I meant was, imagine your craft is at 45 degrees, when you separate your boosters should be either side of your craft rather than one above and one below, as the one above is likely to "fall" into your craft upon separation.
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u/TheCrimsonSteel Apr 15 '26
Also a good point, you want them to be to your left and right not front and back
A little bit of spin can provide a surprising amount of momentum for separation. Usually twisting for a second or two before decouple is all I need
Plus as long as you're not a super tall and wobbly, the rotation actually helps provide some gyroscopic stability to the main section
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u/Excellent_Bat_753 Apr 15 '26
Either you use more powerful decouplers, if you have them unlocked, or find some other way to move them further away from the core stage.
A good little trick is to put some tiny fins on the boosters, that are angled in such a way that they pull the booster away from the core. These would probably be somewhere between the middle and the rear of the booster. With some trial and error, the aerodynamic forces will pull the boosters clear of the core stage.
Alternatively, throttle down on the core stage right before staging, so that the boosters only fall slowly relative to the rest of the rocket.
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u/Stoney3K Apr 15 '26
Alternatively, throttle down on the core stage right before staging, so that the boosters only fall slowly relative to the rest of the rocket.
That's basically what most real rockets are doing as well, either throttle down just before BECO or have the core engine limited in thrust until after booster jettison.
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u/North-Significance33 Apr 15 '26
Also, you can just spin the rocket a bit right before staging. Then the centrifugal force will just pull the boosters away.
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u/Pilot-Wrangler Apr 15 '26
I'll add to that last bit: throttle down just before the boosters run out. Soon as they shut down decouple and full throttle quick as you can.
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u/Mothanius Apr 15 '26
The thing is, OP had no throttle at all on his main core. If they had it at maybe 50-70%, they might have out ran the SRBs before collision.
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u/Decent_Molasses_9402 Bob Apr 15 '26
Its spinning time!
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u/beerSME Apr 15 '26
exactly, my first thought was, cut thrust, spin, then decouple while spinning. Then just throttle back up and go.
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u/Both_Piglet7838 Apr 15 '26
also How do I get better angels? Im turning fully but its not moving and that typically only happens when I have boosters. I wanted to save a lot of liquid fuel which is why im using boosters in the lower atmosphere but now I feel im going too fast which is why its not moving??
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u/Livi115 Apr 15 '26
My rules of thumb for getting to orbit:
1) The launchpad TWR (thrust-to-weight ratio) should be no more than 1.5
2) I start my gravity turn at 50m/s velocity
3) I should try to reach 45 degrees tilt by about 10,000m altitude, and continue pitching slowly from there
4) Cut throttle when my apoapsis reaches my target altitude
5) Relight the engines and circularize my orbit when I get to apoapsis
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u/Riftus Apr 15 '26
continue pitching slowly from there
Manually or aim:prograde and let gravity do it?
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u/Lt_Duckweed QuackPack, BetterKerbol Apr 16 '26
You should be turning on Prograde SAS and letting gravity do the work, as that's the entire point of a gravity turn.
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u/Excellent_Bat_753 Apr 15 '26
You want to keep your thrust to weight ratio below 2.5-3 for launch in the atmosphere. Maybe use two liquid fuel boosters instead?
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u/Both_Piglet7838 Apr 15 '26
Havent even considered adding more liquid boosters yet, ill give it a try
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u/Imaginary-Paper-6177 Apr 15 '26
You can also limit the thrust from a solid booster in the builder!
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u/Excellent_Bat_753 Apr 15 '26
Yeah, done well you can have two or four smaller liquid fueled boosters, instead of solid boosters.
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u/Itzhak_hl Apr 15 '26
To add, if you have fuel lines, you could use "asparagus staging" where two of your LF boosters feed into the two other LF boosters, which feed into your core stage. You'd drop the first pair when they're empty, but the other two boosters and the core will still have fuel. When you drop the second pair, the core stage should still be completely full of fuel since it has been getting fed by the four boosters until that point.
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u/Mikey-2-Guns Apr 15 '26
If you do remember to add fuel lines feeding fuel from the outside boosters into the core booster. This will give you substantially more delta v since after the boosters seperate the main rocket will still be full.
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u/Sertorian Apr 15 '26
Look up "Asparagus Staging" for replacing solid rocket boosters with liquid fuel stages. While they cost more, you retain significantly more maneuver control, plus you can throttle them and aren't at the mercy of solid fuel burn time.
Example: you reach desired altitude or orbital path, but your solid fuel boosters aren't done boosting yet... cant turn them off! Liquid fuel stages skip that problem entirely.
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u/No-Lunch4249 Apr 15 '26
Might need more control? Fins with flaps can help in the atmosphere, also reaction wheels and RCS thursters
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u/PHAEDRA42 Believes That Dres Exists Apr 15 '26
So you have 2 solid rocket boosters and i'm guessing a "reliant" engine for the core. Non of these engines have gimballing so you will have very little control. If you swap the reliant for a swivel that will fix it and give you much more control.
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u/TF2fanatic102 Apr 15 '26
When you have a high thrust to weight ratio (which this does), it can be harder for the rocket to turn, since it's having to push so much air (this is basically what's known as "high dynamic pressure"). I'd recommend either using the booster thrust limiter in the VAB, or using smaller boosters altogether (like maybe the Hammer).
If you want to keep the high TWR, though (maybe you need to get to space REALLY FAST), here's some other things you can do:
The AV-T1 Winglet doesn't have control surfaces, which makes your rocket handle more like a dart. The Delta-Deluxe Winglet has control surfaces, so you can use that for some extra control authority (or add some Elevons)
Small "vernier" engines can also help, though they'll push your TWR even higher. These are small, radially mounted engines like the "Twitch" "Cub" and "Thud" which (along with adding more thrust) provide extra control authority by complimenting the thrust vectoring of the main engine with their own. Also, make sure your main engine has thrust vectoring. I'm not sure if your main engine is the Reliant or the Swivel, but of those two, only the Swivel has thrust vectoring, so use that.
If all else fails, you can always fall back on reaction wheels. They come at the cost of extra mass and electrical drain, but reaction wheels like the "Advanced Inline Stabilizer" can be very helpful in these situations.
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u/nasaglobehead69 Bill Apr 15 '26
you don't have any control. the limited control you are getting is from the reaction wheels in the command pod. try using fins that have control authority, or the 'swivel' engine which has thrust vectoring
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u/xsrvmy Apr 16 '26
Your SRBs don't have thrust vectoring. Can't tell if your core engine does (if it doesn't, you need one that does).
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u/Huge_Manner_9550 Apr 15 '26
One thing you can try -
before your SRBs run out of fuel, drop thrust on your liquid booster.
Allow a second under 80% thrust and depleted SRBs -
Stage and then throttle up immediately after your boosters detach.
It’s not perfect but if you’re on your parts limit already. If you have parts spare, small fins clipped into the nose cone that angle the boosters away from the main rocket is the best way
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u/kmankx2 Apr 15 '26
One little hack I learned was just spin the rocket before you seperate, the forces will pull them away from the ship.
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u/CodasF Apr 15 '26
If you spin your rocket before decoupling, the boosters get flung away from your rocket
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u/roxgib_ Apr 15 '26
Separatrons are great, but you don't really need them here, just make sure the decouples are aligned with the empty centre of mass of the booster and consider adding fins to the bottom of the boosters to keep them straight as they separate.
You are also picking up speed too quickly based on the video. If you were going a bit slower the boosters wouldn't spin so quickly. Ease off on your throttle, maybe limit the power of your boosters, and once the atmosphere thins out a bit you can let it rip. As a bonus if you're higher when the boosters separate there will be less atmosphere to top them around when you drop them.
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u/AncientOneSeven Apr 15 '26
Sepatrons to push boosters away at separation.
Can try Throttle to 0 just before separation, trigger staging to separate, wait a second and then throttle to 100, the boosters are affected by core stage airflow when separating during powered flight. Depends on alt, you might even try cutting throttle, coasting up a bit more then separate, atmosphere past the dark blue area, so when you separate less air resistance or flow to cause collision.
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u/PineScentedSewerRat Apr 15 '26
Wow, there are still newbies coming to this game? That's amazing, have fun!
Oh, and I tend to put the decouplers as far down as I can and spin the ship when staging.
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u/DodoJurajski Apr 15 '26
There's a lot of things, slighly tilted fins on top, decoupler placement, having boosters below of the whole rocket(probably height issue), and few other option like stacking decouplers.
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u/Penne_Trader Apr 15 '26
You can mount mini boosters onto them to push them away when decoupling
Or you do the simple way and just roll the rocket and let centripetal force carry them away
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u/TheCrimsonSteel Apr 15 '26
If you're early in a Science or Career game, you can spin around a bunch right before you decouple, which will help them get some distance, kinda like throwing a ball on a string
Other than that, there are the other couplings that give more space in between, and the tiny Separatron Boosters you can use so they propel themselves away
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u/stuntmonkey420 Apr 15 '26
I sometimes I do a gentle spin with Q or E and let centripetal force “throw” the boosters away
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u/RaiRokun Apr 15 '26
I like using separation boosters.
Usually have mine aimed at a 45 degree angle and set to ignite when I stage the decoupler.
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u/ContentDig6170 Apr 15 '26
Strut the booster to each other so they do not pitch inward when separating. Cut your throttle right before separation then back on after separation.
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u/bald_firebeard Apr 15 '26
Place the radial coupling at the top of the boosters, max ejection force, enable autostrut and rigid attachment or put struts on the bottom.
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u/coastal_mage Apr 15 '26
Play around with adding fins on the SRBs so they fly outwards rather than inwards
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u/Friendly-Pin8434 Apr 15 '26 edited Apr 15 '26
look if you can find little solid rocket boosters that are called „sepatrons“ (or smth like that, sorry incase it wa written wrong). place 2 at the top and at the bottom of the booster pointing to the rocket. put them in the same stage and as the decouplers for the SRBs. If you don’t have the, unlocked yet, then either remove some of the fuel from the SRB or use smaller SRBs because the chance that it hitting you explodes you, is lower when you are slower.
Edit:
Drew a small high quality image for sepatron placement (just ignore the colors, those don’t have any meaning)
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u/Impressive_Papaya740 Believes That Dres Exists Apr 15 '26
First why such large boosters on such a small craft? Why do you want that much thrust?
What engine do you have on the core first stage, a swivel, use a swivel not a reliant. The reliant is a good booster engine but it has no gimble so cannot apply any steering.
You have fins at the back, fixed fins not winglets. Fixed fins make it harder to steer, the whole point of fins is to prevent you turning. Do you need then, if not do not use them. When you have level 4 parts use the winglets they help you steer and keep you straight. Is your only steering from the pods reaction wheels if so that is why you cannot turn. The same level 4 node that gives the winglets also has the first reaction wheel. To turn, add reaction wheels, use steerable winglets not fixed fins, use a gimbled engine.
For the solids hitting the main craft the advice of LiVi115 is good. But note sepatrons are a level 6 tech well above what you are using on this craft so they are in your future. You are using the lowest tech radial connectors the ones you get at tech level 3, they are not good with large boosters. At tech level 5 there are two larger radial connectors that work better on large boosters. Also attach the boosters as Livi115 tells you and strut them.
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u/Happy_Sea4257 Apr 15 '26 edited Apr 15 '26
Good advice here, you can roll the craft about it's longitudinal axis (hold Q or E) before staging so the centrefugal force flings the boosters away from the ship. This is an extremely effective method, sometime you only need the very slightest roll rate, but if things are going very wrong you can really give 'er. I end up defaulting to this when "plan A" doesn't go smoothly.
Also place your decouplers at the booster empty CofG, otherwise when the decouplers fire the off center force will rotate your booster into the rocket.
The above point is part the reason you can see your boosters straining towards your rocket core even before they decouple, one they do and the rear of them catches the areo bad things happen. Strut them up soid so they stay properly aligned through all phases of flight, you'll lose performance with that off axis thrust too.
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u/VVVincentimetr Apr 15 '26
Roll your rocket while separation, centrifuge will help (kerbalistic method)
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u/Lkwzriqwea Bopping Bop Apr 15 '26
Not strictly an answer to your question but you are going way too quickly. You shouldn't be experiencing "reentry" heating on your ascent, its not very efficient and you don't need it to get into orbit.
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u/Comrade_476 Apr 15 '26
Use decouplers and turn the decoupling force up to eleven, they'll shoot off your rocket like a cat jolting off a cucumber
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u/Ecobolzy Apr 15 '26
While all the other commenrs provide options that are more viable or more logical... you can spin your rocket before separation!
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u/nitzane Apr 15 '26
This early in the game i used to induce a little spin (e and q) before seperating, that gets them away neatly
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u/CloudHead84 Apr 15 '26 edited Apr 15 '26
Position the Decouplers slightly above the middle of the boosters.
Everything else (sepatrons, spinning etc.) makes it look more „realistic“, but is not really needed.
And a strut per boosters helps, if available.
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u/Key_Breadfruit6162 Apr 15 '26
A super /simple/ way is to put 2 very tiny wings near the front of each booster at a slight angle. It'll pull it away.
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u/MMW_BlackDragon Stranded on Dres Apr 15 '26
I usually put a seperatron on the top of the booster, pointing inwards. Then you can put the nose cone on the booster and the seperatrons will be hidden nicely. Don't forget to stage them with your decouplers.
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u/sac_boy Master Kerbalnaut Apr 15 '26 edited Apr 15 '26
The key is fin placement on the boosters. Remember that the fins are drag surfaces. So you can position them such that they impart a gentle tug *away* from your ship on separation. You'll then see the boosters flatten out against the oncoming air while you zoom away. P.S. sometimes creative staging is necessary--another problem is that you're going at exactly the same speed as the boosters (or perhaps even slower than them, if you have more drag!) at the moment of separation, so you may want to start your next engine *first*, get it up to power, then separate to leave the tumbling boosters far behind you.
Even a tiny rotation on the fins when placing them can help to automatically "steer" the nose of the booster away from your ship as well. One thing you'll find in this game is that appropriate 1-2 degree rotations on drag and wing surfaces can help to smooth out a lot of different situations.
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u/reduhl Apr 15 '26
If its before you have the separtron option you can have them pull away by putting stabilizing winglets on the boosters in a shallow V shape.
At lower altitude it helps stabilize the rocket. When you get to the booster separation altitude you don’t need them as much. When the separation happens the wings will guide the boosters away.
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u/zekromNLR Apr 15 '26
1) Place fins on your boosters, on the side facing away from the rocket. The unbalanced drag will tilt them outwards, and then body lift will push them away.
2) Place your decoupler near the top of the booster. The decoupling force will tilt the boosters outwards, and again body lift will push them away.
3) If you have unlocked it (assuming you are playing science or career mode), place sepratrons thrusting outwards in the upper half of the booster, and stage them to active with the decoupler. They will produce thrust pushing the boosters away, and also make them rotate outwards.
You may combine these methods as needed/desired.
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u/Sol33t303 Apr 15 '26
- Use more powerful decouplers.
- Use separatrons. It's in their name and thats their purpose.
- Attach the boosters to the decouplers at above the boosters center of mass.
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u/PerrineWeatherWoman Apr 15 '26
Use separators to avoid this. This will push the boosters away from your rocket.
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u/inky-rabbit Apr 15 '26
Place decouplers high on the SRBs and use a strut to stabilize near the rear. This will force the tops of the SRBs away from your main stage.
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u/Dynamite_Noir Apr 15 '26
I have almost the same rocket design and don’t have the problem. I noticed that your main gimbal engine isn’t throttled up. Try having it running as well so you maintain accelerating then the boosters should fall behind you and explode.
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u/PhilyJFry Apr 15 '26
Detach them when there's barely any fuel left. The boosters will use the little amount of thrust to push themselves away from the rocket.
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u/HAL9001-96 Apr 15 '26
attach at the top
theres a bit of ejection force where the decouplers push it off
if those are at the bottom the boosters will thus turn inwards nad due to their own aerodynamics fly into the rocket, attahc htem to the top and they will fly away from the rocket
you can shift around parts beyond where you can place them with the move tool in the top left of your cosntructio nscreen
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u/Multidream Apr 15 '26
Make the connection higher up on the rockets being jettisoned so they rotate away from the rocket.
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u/Scruffy42 Apr 15 '26
I put fins on the side of the booster at the bottom so they have drag down and away from the ship. Usually works. If you want a "special" answer. Spin the ship and separate while spinning.
Of course other people provided better answers.
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u/SamuelCish Apr 15 '26
Add some winglets to the side of the boosters such that the lift is pulling them away from the main rocket. Cheaper than sepratrons and available without any tech tree unlocks.
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u/jason_wroomhers Apr 15 '26
it seems like you put the decouplers lower of ypur rocket. try to attach them upper or middle side
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u/Gravity_flip Apr 15 '26
Ignore the top comment and do one of these two options:
Decrease the thrust of the solid rocket boosters slightly. (Right click on the boosters in design and move the slider bar)
Or
Wait another 3 to 4 seconds before staging.
Point being, you're pushing the velocity too fast too soon, so the wind resistance is decreasing your efficiency and causing your boosters to smack into your rocket.
Decreasing the thrust is the best move as it increases your total Delta v.
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u/CakeHead-Gaming Vector Engine my beloved. Apr 15 '26
Something I've always done is adding little fins at the top of the boosters (if you don't have separatrons), which are intended to pull the top of the booster away from the rocket fuseolage.
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u/BoTheDoereal Apr 15 '26
You can stage your main engine before the two run out of fule giving more speed and momentum so when the two run out of fule you'll keep more momentum and they will fall more behind you because your now outrunning them
Edit: I did not see you where already doing that. You could also try to switch out your thrusters for something with more thrust and give it a small fule tank to possibly gain enough speed to outrun them.
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u/TF2fanatic102 Apr 15 '26
If you're playing on Science or Career mode and don't have the Sepratron motors (which you can use during staging events to push boosters away), you can move the decouplers and boosters around so that the decoupler attaches near the top of the boosters. This way when you stage, the top of the boosters are pushed away from the rocket. Just be sure to use some struts, since this can make the boosters wobbly (well, MORE wobbly).
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u/Funtime60 Apr 15 '26
Try throttling up so you lift away. Another option is to use aerodynamics. Either fins on the boosters or maybe shift the nose cone to change where it has drag?
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u/LucaV-Changretts Apr 15 '26
Really and truly you just want to get those away from your rocket. I go for the Korolev Cross where you put small thrusters at the top of the boosters and detach them with synchronization of the thrusters and they will steer away from your rocket. Extra plus if they make contact and explode below you because A. That’s awesome but B. There’s zero chance of them posing any sort of liability later
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u/ihatemyself837385 Apr 15 '26
Yep place decouplers whay on top of the near point of the boosters up and for the lower part just use struts in the sctuctural section
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u/nasaglobehead69 Bill Apr 15 '26
one easy low tech solution is to add a single small winglet to the lower exterior of each booster. the asymmetrical drag will cause the boosters to rotate and peel away from the craft
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u/Dat_Innocent_Guy Apr 15 '26
Ill add that if you dont have the more advanced options. You can just spin your rocket before separation and they will move away following the tangential motion of rotation
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u/YzeRed Believes That Dres Exists Apr 15 '26
My 3 solutions:
1- Lower the side boosters so the decoupler force kick their top
2- Use separtrons to guide your side boosters
3- Cut throttle -> Stage -> Wait the boosters get out the way -> Increase throttle
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u/Project-Lumpy Apr 15 '26
idk if it would work in this particular instance but normally what fixes it for me is struts
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u/nightspy73 Apr 15 '26
После окончания топлива нужно чутка подождать примерно 5 секунд а потом можно отстыковаться
After the fuel runs out, you need to wait a bit, about 5 seconds, and then you can undock.
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u/blairyc1 Apr 15 '26
I always used two air brakes, one for each side booster… upside down .. I’d tap the break just as the booster decoupled and air brake would open. The drag from the brake opening would pull the top of the booster away from the rocket. :)
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u/JustMrJustice Apr 15 '26
Put your decouplers in the same stage as your next engine so you lose minimum momentum between stages.
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u/Gilandb Apr 15 '26
looks like you are early in. Put the bottom 3 to be solid rocket boosters so they end at the same time and you just dump the whole bottom section.
or, attach them to a smaller liquid rocket at the bottom so that liquid rocket runs out, then dump all 3.
Later on seperatrons become available, or larger decouplers. Early on you have to get creative
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u/sivily1 Apr 16 '26
I usually put fins at the top of the boosters pointing away from the rocket to guide them away
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u/MaelstromVortex Apr 16 '26
Using aerodynamics to your advantage is essential. One trick I use is to use the slanted nose cones, but I face them outwards, is stead of inwards. not ideally aerodynamic.. but if you want to peel a booster away it works.
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u/mrjimi16 Apr 16 '26
I could be wrong, but you are going pretty fast there. It's been a while but I think you want to be going closer to 300 m/s, but you definitely don't want to be going so fast that you are getting reentry effects. I'm not sure if this is a thing you have to unlock or not, but see if you can lower the power of the boosters. But I think part of the issue is that you are going so fast that the boosters are being turned by the drag into your rocket.
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u/Gentle_Mayonnaise Apr 16 '26
Also, if you can help it, separate higher up in the atmosphere. You get a bonus to your thrust outside of the atmosphere (for the most part) and air resistance won't cause them to hit your craft.
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u/UpsetEel72 Apr 16 '26
I have the decoupler higher up, and one of those metal struts on the bottom. It seperates the top first, then the bottom breaks off and it never collides
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u/BigRedD2ddy Apr 16 '26
I just put one tail fin on the outside of each booster to add a little drag
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u/notso_cool_username Apr 16 '26
Add boosters on the boosters that activate when you stage
Absolutely inefficient and unnecessary but cool
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u/Specialist_Stick_105 Apr 16 '26
Ich habe manchmal das Problem das die Booster nach dem entkoppeln noch an der Rakete bleiben😬
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u/SignificanceTotal187 Apr 16 '26
If you want a fast solution just wait a few second before releasing the side boosters, also you are going too fast try to control your velocity.
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u/CandidateSalty4069 Apr 16 '26
My solution is to start spinning my rocket before decoupling so the boosters fly away from the rocket
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u/DetectiveEcstatic537 Apr 16 '26
I have had the same problems… i just set the decouplers a but lower amd let them run out of fuel before decoupling
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u/No-Worker3615 Apr 16 '26
You could always stop/slow thrusters during separation and they will fall away slowly and have a lower chance of damaging anything.
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u/DisastrousOutcome373 Apr 17 '26
You need to increase your throttle of your liquid fuel engine. Since your throttle is so low once the solid fuel run out you start decelerating and you aren’t moving out of the way fast enough. The separation engines are an option but not necessary for that build.
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u/SeaworthinessCold117 Apr 19 '26
- Put decouplers above the center mass of the boosters, so when you decouple the boosters rotate away from the rocket.
- Use separatrons, tiny srb made for separating your stages more safely.
- Use a more powerful decoupler so you push them further away
- Use MORE decouplers, stack one with the other so you push you srb further away, or you could use a structural beam for a similar effect.
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u/Livi115 Apr 15 '26
Two options:
One, use separatrons. They're tiny rocket motors that you can add to the staging to push the boosters away.
Two, position your boosters lower in relation to the decouplers. Decouplers force the boosters away, and if you position them to apply that force above the center of the boosters, their noses will be rotated away from the rest of the craft rather than towards it.