Venting/dumping fuel

[Mech]

I keep finding with my spaceplanes that I am overweight in orbit. Sometimes fatally. A surplus of fuel as a result of a lighter payload means that the weight distribution of the plane is off, or that I won't be able to control it very easily.

Is there any way to vent or dump surplus fuel? I've looked around for a few mods, but most I found were from 2013-15. Way too outdated. I feel like fuel dumping is a pretty useful feature, and should probably be added to the game stock...

[Elementus]

if you right click on the tanks you can move fuel to other tanks, that should fix your weight distribution problem

[Mech]

Originally posted by Elementus:

if you right click on the tanks you can move fuel to other tanks, that should fix your weight distribution problem

Pumping is something that I am well aware of, but thank you. The actual problem with my workhorse spaceplane is that there are no tanks until right at the back, so pumping mass to where, in theory, it would solve the problem is impossible since there's nothing to pump it into. And, as I said, weight distribution is still only part of the problem. The other problem is that it's very difficult to control when it weighs that much, unless I were to add oversized control surfaces.

[RoofCat]

design planes so the CoM doesn't move much for full/empty. Best way to do so is place most fixed mass (crew, science, engines) close to CoM. And then have fuel balanced on both ends.
Or since you have 2..4t cockpit, have 2..4t engines on tail and the rest on sides of CoM. Something like that works guaranteed even without much testing.
https://steamcommunity.com/sharedfiles/filedetails/?id=1304789310

As for dumping fuel it would be useful feature. I have had situation when I realized my Laythe plane may have return issues just because I have too much heavy Oxidizer I don't need at all for Laythe launch unlike I supposed I would (because Rapier top velocity is so close to Laythe orbital velocity already). So I just edited save file (reduced Ox to 0) and then changed setup for saved design for next flights.
Procedural tanks where you can adjust fuel proportions without wasting mass would be useful too. There are none in stock game either. So there is that.

Well KSP is about trial and error. So in theory I should have sent test plane and then the real one. Like they do at NASA for many things. And it would have been just fine.

For heavy planes there are problems with SAS. Because there is no MK3 format reaction wheel. Which has been asked to develop probably 1000 times, but somehow no one has heard that.
Also there is that point, that reaction wheels are actually super OP in KSP already. In real world they are quite limited.
What people do is place 2.5m reaction wheels in cargo bays. Alternatively you can place those or 1.25m ones right under engines depending on engine size.
https://steamcommunity.com/sharedfiles/filedetails/?id=936058885

Still, heavy ships fly heavy. And do look ugly for most part. You can't install one reaction wheel meant for 20t ship on a 400t one and hope it will be enough. No, you will need 400/20=20 of those to have the same agility. It is a lot, but so is your mass. Simple math.
https://steamcommunity.com/sharedfiles/filedetails/?id=881268455
engines aren't aligned with CoM here. But they are balanced on both ends and stay there. Which does work almost as nice (a bit worse agility due to mass leverage)

Finally regarding heavy stuff - it has almost no delta v advantages if you scale it properly. Some small due to lower payload percentage, but really not that impressive. At some point it may actually have disadvantages as you will have to use some rigidness boost solution for superheavy stuff. Struts, extra parts.

Good planes no matter the size will be limited to ~5500..6200m/s left on low Kerbin orbit with airbreathing/nuke stuff. No point building huge. Medium works much better on most occasions. Much more enjoyable to fly too.
https://steamcommunity.com/sharedfiles/filedetails/?id=1203340192

[edorward]

You could always just burn the fuel. Burn prograde then turn around and burn retrograde. Not as good as just dumping, but still an option.

[Greg]

I create external fuel tanks that I can jettison.

[Ogre420]

http://forum.kerbalspaceprogram.com/index.php?/topic/139223-ksp-v112-tac-fuel-balancer-v27/

It also dumps fuel

[Chibbity]

Re-design it.

You should be carrying fuel centrally to avoid this problem.

Here's a good mod to help with that: Let's you carry fuel in any of the stock wings.

https://forum.kerbalspaceprogram.com/index.php?/topic/169799-145wetterwings/

CorrectCOL mod will let you know in advance if your plane is unstable at any given point between wet and dry.

https://forum.kerbalspaceprogram.com/index.php?/topic/160231-141-correctcol-stock-aerodynamics-design-aid-continued/

[Bomoo]

Originally posted by Ogre420:

http://forum.kerbalspaceprogram.com/index.php?/topic/139223-ksp-v112-tac-fuel-balancer-v27/

It also dumps fuel

This is all you need, and something that should've been standard in the stock game if they intended for people to build and fly spaceplanes effectively.

[Chibbity]

Originally posted by Bomoo:

Originally posted by Ogre420:

http://forum.kerbalspaceprogram.com/index.php?/topic/139223-ksp-v112-tac-fuel-balancer-v27/

It also dumps fuel

This is all you need, and something that should've been standard in the stock game if they intended for people to build and fly spaceplanes effectively.

What lol?

You don't plan for failure, right? Why bring fuel just to dump it?

If your Spaceplane needs to dump fuel, it should be re-designed. No offense.

[andylaugel]

This is an option I do wish was in the stock game. During an early Moho base delivery mission, I found I had accidentially packed 28,521 extra units (or 142.6 tons) of unwanted oxidizer aboard my fuel depot. Fortunately I found it in time to ditch the fuel depot and complete the mission, but I'm still working on recovering it.
https://steamcommunity.com/sharedfiles/filedetails/?id=729714044
https://steamcommunity.com/sharedfiles/filedetails/?id=729714408

[Dialator]

The only way to dump I know of involves detaching a part as someone has already suggested. Though certainly not as easy as pumping fuel into space, you could attach some empty tanks under your wings with the structural pylons so you could pump fuel in to them to either balance or decouple them to dump the extra weight.
However, you mentioned this is mostly a problem with transporting lighter-than-usual payloads, so why not modify the fuel levels in the editor before launch? If it's just that you never think about it until it's too late (always happens to me) it might be helpful to write the weight of the payload for which your craft if designed and the weight of the fuel only in the vessel description. I would assume the weights would be proportional. So if your usual payload is 50kg and you use 100kg of fuel for the mission, you would know for a 25kg payload you would only 50kg of fuel for the same mission. It would probably be useful to write the weight per unit of fuel somewhere as well so you will know exactly how many units to subtract for the correct weight.