Lower main stage thrust

[Iguas]

Hello, i'm currently doing a rocket that work a bit like the Falcon 9 : boosters kinda the same size as the main stage

So i'd just like to know if there's a way to lower the main stage thrust when the boosters burn, and then turn it back to 100% when i drop the boosters.

I'd like if to be automatic (with stage or timer etc...) and i'm playing modded, so no problem if it's a mod.

Thanks a lot ! 

[Geonovast]

Some mods that may help of you don't want to go full on scripting.

Otherwise there's always KoS

 

[Iguas]

Thanks a lot !! i'll take a look at all those mods, but no, i really don't script ^^

36 minutes ago, Geonovast said:

Some mods that may help of you don't want to go full on scripting.

Otherwise there's always KoS

 

Ok,  Smart Parts look like a good one for my problem, thank you dude !

[Aegolius13]

In the stock game, you can right-click the engine you want to throttle down and use the "thrust limiter" slider, while leaving the throttle at whatever you want the side boosters to be.  However, this is not very practical if you have lots of engines per core, as with the real Falcon 9 / Falcon Heavy.

If you do have lots of engines, though, you can also do it by splitting your engines into groups and turning off a portion of them using an action group.  For example, if you wanted a ring of 8 engines, you could instead use 4-way symmetry to plant two different sets of 4 engines.  Then assign one of the groups to toggle on/off with an action button - that will effectively cut that core's throttle in half.  You don't get pinpoint control, of course, but it's not too bad.  And actually somewhat realistic (i.e., Falcon 9 lands with only 1-3 engines lit since very little thrust is needed).  [EDIT - maybe a better historical example - the Saturn V shut off one of the five engines on its first stage in order to control acceleration.]

Edited January 7, 2019 by Aegolius13

[AeroGav]

Ah sounds like you're making a Delta V Heavy /  Falcon Heavy,  with core stage throttleback.

For the normal Falcon 9 full thrust,   would using  a Vector for the booster stage and a Terrier upper stage approximate the thrust and isp differences between the two stages, while keeping stage diameter constant ?

[Iguas]

22 hours ago, AeroGav said:

Ah sounds like you're making a Delta V Heavy /  Falcon Heavy,  with core stage throttleback.

For the normal Falcon 9 full thrust,   would using  a Vector for the booster stage and a Terrier upper stage approximate the thrust and isp differences between the two stages, while keeping stage diameter constant ?

I'm not making any existing rocket, but i really like the look (and lifting capabilities) of BIG boosters using liquid fuel engines, and with those mods, it works great ! i use a timer that set the main engine thrust to 40% after 40 sec (to keep high TWR at liftoff) and when the boosters are empty, a ressource detector sets back the main engine to 100% (thanks to Throttle Liit Extended)

It really works great, and the main stage burns for a very long time without using unrealistic fuel lines !

[Geonovast]

19 minutes ago, Iguas said:

It really works great, and the main stage burns for a very long time without using unrealistic fuel lines !

You don't need the fuel lines.  You can enable crossfeed on the booster decouplers, then set your fuel flow priority so the boosters drain first.  That way you can run your center core at full throttle and still have it be full of fuel when the boosters detach.  SpaceX had considered this for the Falcon Heavy, but opted for the lower center thrust option instead.

[Iguas]

On 1/8/2019 at 7:47 PM, Geonovast said:

You don't need the fuel lines.  You can enable crossfeed on the booster decouplers, then set your fuel flow priority so the boosters drain first.  That way you can run your center core at full throttle and still have it be full of fuel when the boosters detach.  SpaceX had considered this for the Falcon Heavy, but opted for the lower center thrust option instead.

Yea, but it still a difficult thing to do, SpaceX stopped considering this because of conplexity i think, and i'm pretty sure only the shuttle used it.