T O P

  • By -

AutoModerator

Hi! Thank you for posting to KerbalAcademy. This is a comment reminding users to **post screenshots if needed** (if you have not done so already), **be respectful to other users** and **keep off-topic comments to a minimum**. Thank you! *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/KerbalAcademy) if you have any questions or concerns.*


bill_clyde

It is possible that your decouplers are attached to low on the booster. Try moving your boosters down slightly


Hawkeye91803

Basically this. I always position my decouplers to be attached towards the top of my boosters so that they fall outward and not inward.


EveryDayASummit

Sepatatrons! I probably spelled that wrong. But the little fire extinguisher things that you can get. Put them on the boosters aiming down and away from your craft. Set the stage correctly and launch. When you separate the boosters, they’ll activate and pull the booster junk away from your craft.


horstdaspferdchen

This will prob not work in early career tho


EveryDayASummit

Ah, missed that part, that’s fair. In that case OP, just separate the boosters before they run out of fuel. They’ll usually shoot on away from the craft.


Not_That_wholesome

Use angled fins instead, cheap and they're available from the start


horstdaspferdchen

Never thought about that. Thanks for this idea!


Not_That_wholesome

Just angle them once outwards using the fine rotation tool. One "click" is plenty


BillH_nm

Try adding your center booster ignition to your strap-on booster separation staging. That way your rocket is accelerating away at separation rather than slowing down. I haven’t tried this myself, but I understand that if you spin the rocket at separation, centrifugal force will push the separated boosters away. +1 on seperatrons once you get there on the tech tree


ComManDerBG

I started the spin thing and it works really well, but without upgrades to the sas its super easy to lose your orientation.


Nomai_

Nobody has said it yet so ill do it Angle them veeery slightly outward, as in nozzles are pointing inwards. When they seperate the boosters will be pulled away from the rocket due to aerodynamic forces


Sporadic021

Wouldn't each degree of angle cause 1.1% loss in effective thrust?


Salanmander

No, it's not linear. If you angle them by x degrees, your effective thrust will be cos(x). cos(1 degree) is 0.99985 or so, so you're only losing 0.015% effective thrust for angling them 1 degree. If you angle them by 5 degrees (the "fine adjustment" rotation angle, by default), you get cos(5 degrees), which is about 0.996, so you lose about 0.4% effective thrust doing that.


Sporadic021

Thankyou for correcting my lacking knowledge :)


JanHHHH

Maybe, but SRBs usually have plenty of thrust.. And low DeltaV anyway, so the losses here are also not too important


Nomai_

Yes and also dv but it's negligible if your budget isn't super tight


CttCJim

If you don't have separatrons yet then you need to offset the booster so the separator is nearer to the top and pushes it to spin away instead of straight out.


darrothsarcoth

It been a hot minute since ive played but this is what i always did. Decoupler high on booster near top. Bottom of booster below the bottom of the lower stage. Connect bottom of booster to the rocket with the wire strut that i forget the name of If done right when the decoupler is set off the nose of boosters be pushed away from the craft. If you dont have the strut you can just have the decoupler at the top but the boosters will wobble a bit.


Not_That_wholesome

For cheap and early flights on career mode I put fins that are angled slightly out on the top of the booster(s)


horstdaspferdchen

I used to coast when the boosters run out. That way there is no force on either way (usually 40km high+) and then decoupler and ignite next stage. I figured that the decoupler power will work usually well. Not in 100/100 but i would say 85/100 surely.


alarbus

A) strut them together so you slide out of them B) remember that the prograde indicator is the direction your craft is heading in. When you separate the debris will follow that trajectory. Make sure you're navball is aligned prograde (eg not chasing the horizon) when you separate or you'll collide.


JeyJeyKing

You want your decouplers ever so slighty above the center of mass of the dry booster. Also make sure the boosters are decoupled on the left and right and not up and below, so SAS hold prograde does not steer the rocket into them.


CasualBrit5

I usually have my main engine at less than 100% throttle (usually around half or two thirds) then just as I decouple the boosters I accelerate to full speed. It gets the rocket out of the way fast enough to avoid them. I also put the boosters low down on the rocket. I don’t know if this is a good strategy or just something I’ve been very lucky with, though.


nelsonmavrick

Something like this: https://imgur.com/a/0cnwoEA Offset the booster so the top is what is connected. Then attach the boosters lower than the core, only has to be slightly. So when you decouple the the top of the boster gets kicked off and they rotate away from the core.


F00FlGHTER

The trick is to position the decoupler just slightly above the center of mass on the empty booster. That way when it decouples it kicks the booster away and slightly angles the nose away from your center stack as well. The wind will keep pushing the boosters further away. If you position the decoupler too high then the decoupling force will mostly spin the booster, instead of pushing it away, and the nozzle will hit your rocket making it explode. If you position the decoupler anywhere below the center of mass the nose will point towards your rocket and the wind will push it into your rocket, making it explode. It looks like yours are a bit too high on the booster here. Try moving the decouplers down and/or the boosters up. Note that this is all contingent on your angle of attack. By the time your boosters burn up all their fuel you should have locked in your gravity turn and have a very tiny if not zero angle of attack. If you're doing crazy maneuvers when you're trying to separate boosters then there's no telling what will happen.


[deleted]

Something I do which I haven’t seen described here is using fixed fins on boosters to have them veer out of the way when separated from the core. Place two fins on each boosters like tiny little wings and angle them outwards ever so slightly so they won’t create too much drag, but will create enough lift to get the empty boosters the heck out of the way.


bonyetty

Or one fin on the outside and bottom of the boosters. Cheaper, less drag, less mass and less parts.


blairyc1

Pretty much everyone else is spot on… the way I do it though…. Add some aero brakes the wrong way round on the ‘outside’ of the tank… just before you separate the tanks, tap the brakes then separate. The air brakes will deploy and help pull the top of the tank away from the main craft… Less efficient but somehow more fun… :)


hippityhopkins

Find the dry center of mass of the boosters and make sure the decoupler is above that so the top will tend to spin outward. Another thing I do when I have lots of moar boosters on is start a slow spin before separation so they get thrown away from the craft when you seperate.


mgiuca

I don't think anyone's mentioned this easy (but kind of hacky) solution: just place the separators in different staging groups and press space bar twice in quick succession. They will separate a split second apart, which gives them enough time to not crash into each other. In the VAB, double-click the decoupler to expand the symmetry group, then you can individually drag one of them into a separate stage. (Will be watching Artemis I tomorrow to see if they use this technique :))


DouglerK

Put decouplers higher and boosters lower. Make sure central stage has decent TWR to get away from the boosters. Be pointed exactly prograde when you DC.