Fuel depots?

[Cloakedwand72]

Are they worth building like to extend the mission range of second or third stages of rockets or as a build off point to refuel lander's or build interplanetary ships off of?

[Fierce Wolf]

Fuel from Kerbin? No

Fuel mined from Minmus? YES

[Superfluous J]

A LKO fuel depot is not actually all that bad an idea. You can streamline your fuel lifter and get really comfortable flying it with multiple deliveries, and then you can launch your crazy Jool monstrosity with it's own fuel to get into orbit, and then refuel to head off to Jool. This combination may take more in-game time, but will be far less of a logistical nightmare and may end up taking less real-life time to achieve.

The general problem I've found with fuel depots is except in specific circumstances (like a crazy Jool monstrosity) it's easier to just launch with the fuel you need in the first place.

And to 2nd @Fierce Wolf a Minmus refueling base can be not only fun to set up, but use. Even if it's not strictly necessary most of the time.

[AHHans]

Well, people play differently!

Apparently @5thHorseman doesn't like orbital refueling as much as I do. Essentially all my interplanetary craft launch with only enough fuel to get to my gateway station in a 500 km Kerbin orbit. Which is refueled with a large miner from Minmus, just as @Fierce Wolf said. Exceptions are craft like Eve Anywhere which was designed to be self-contained or Nauvoo Asteroid Station which got one refueling visit from my Minmus miner in Kerbin orbit and then moved to Minmus orbit where it took several trips of said miner to fuel it up. (Doing it in Minmus orbit not only saved round-trip time but also saved the fuel needed to get into Kerbin orbit.)

So, yes, it depends on your playstyle if a refueling depot is worth it. I like building deep-space infrastructure, and also have several craft that do multiple interplanetary trips and refuel in-orbit when needed. But if you "just" want to launch single missions, then the hassle of (multiple?) trips to Minmus might be too much, when you just can build a lifter big enough to get a kiloton or so of payload into orbit.

[Hotel26]

8 hours ago, Cloakedwand72 said:

Are they worth building like to extend the mission range of second or third stages of rockets or as a build off point to refuel lander's or build interplanetary ships off of?

Emphatically yes, in general.

KSP is rich in challenge, though.  For those who wish to challenge themselves against the tyranny of the rocket equation or recreate the rigors of the space program to date, I guess they might elect to forgo this step, but it does limit payload and therefore mission possibilities.

Paraphrasing Robert Heinlein, "LKO is halfway to anywhere".  Getting fuel supplied from KSC to LKO is cheaper than from any other source (i.e. mining and with the exception of on the launchpad at KSC), although I don't rule out the Mun or Minmus as an interplanetary departure point (just haven't embraced the additional complexity of launching from those departure points...).  I do use the Mun as a recovery and refueling point for interplanetary accelerators and asteroid-hunters.

Finally, would anyone predict that Mankind won't have any kind of space infrastructure (for neither fuel nor payload transfer) in the 22nd century?

(And I didn't mention how much FUN that extra play time is!)

Edited February 1, 2020 by Hotel26

[Guest]

Early game, I set up fuel depots around the bodies I want to explore. 

After I have ISRU, I set up refueling operations. I usually have one at the Mun, which I use as the launch pad for long-range missions (beyond Duna). I find the burns are easier to plan from there than from Minmus even if there is a small loss of efficiency.

[DunaManiac]

22 hours ago, Cloakedwand72 said:

Are they worth building like to extend the mission range of second or third stages of rockets or as a build off point to refuel lander's or build interplanetary ships off of?

Frankly I only use fuel depots for SSTOs, because they have to lug around wings and jet engines and it's harder to get enough fuel for interplanetary missions, for example.

[RizzoTheRat]

I don't really see the point of fuel dumps in Kerbin orbit.  If you're launching a big craft yes it can a lot easier to launch the fuel separately, but with a fuel dump you have to dock the ship and the tanker with the fuel dump.  Why not just dock the ship with the tanker instead?  Similarly if you're bringing in fuel from Minmus because it's cheaper than launching it from Kerbin, why not just dock with the ship and the tanker?  Unless the ship needs multiple tankerfulls of fuel, in which case you need a bigger tanker! 

Fuel dumps around other bodies do make sense to me though.  In the early game I park a fuel dump and lander around the Mun and Minmus, and have the crew do 2or 3 landings per mission.  When the next crew goes up they have an oversize transfer stage to top up the tanks on the fuel dump.

However as I also play with USI-LS I find stations are a useful staging point for crews to top up their habitation and reduce homesickness time before spending a while in a smaller ship, so as I have the station there I make up the payload weight on my standard lifters with additional fuel so do end up using my stations as fuel dumps