[Uneven fuel ducting when feeding from one tank]

This *might* be a mini bug but I'm assuming my naivety of gameplay mechanics for now.

Imagine an asparagus setup as shown (excellently I might add) in the wiki:

S1 is a Rockomax X200-32 (1440 capacity) fuel tank with a mainsail engine beneath it.

S2-S4 are all Rockomax Jumbo (orange) fuel tanks with skipper engines beneath them.

Fuel ducting exactly as described in the above image and everything works just fine.

Works fine

Now add directly above S1 a payload, comprising of:

Wide stack decoupler (not fuel crossfeed capable)

Rockomax Jumbo (orange) fuel tank

Probe core of your choice.

This also works exactly as expected, with the payload jumbo fuel tank left unmolested by virtue of the non-crossfeed capable stack decoupler.

Works wonky

Now assume you're happy to use that payload fuel to achieve orbit, you want to get a fuel can into space but you're happy if it's an empty fuel can. (first discovered this issue when launching a space station fuel depot module - have simplified the model to test the issue).

So you run a pair of fuel ducts from the payload jumbo tank to the two jumbo tanks in S4.

I expected fuel to first drain from the payload can evenly into the pair of S4 tanks, then when the payload can was empty the S4 pair would start to empty.

In reality what happens is that fuel does indeed drain from the payload can, and one of the S4 pair remains full whilst the payload can is draining. The other can in the S4 pair however slowly drains from launch.

Net result is that one of the S4 pair runs out of fuel a few seconds before the other one - resulting in a rocket fuelled acrobatic ballet which, if adopted by the Bolshoi, would encourage a lot more people to see Swan Lake.

Maybe solution

Curiously, feeding the pair of fuel ducts into the S3 pair rather than the S4 pair seems to work ok (though still perhaps slightly out as a twitch upon running dry suggests a minor imbalance). In this setup fuel drains apparently evenly from the payload tank and both the S4 pair such that all three appear to run out at almost exactly the same time; the S3 pair remain topped up and untouched until the S4 pair runs dry (and are subsequently jettisoned).

In terms of absolute efficiency this solution might not be optimal as the payload mass is at it's lightest just as you jettison two engines (and 1300kn of thrust) rather than before, but it's probably good enough for Kerbal rocket science.

[Docking port...Dangerous to dock.]

I think I've seen something similar to this a couple of times. Successful dock is immediately followed by a resonating wobble which amplifies until pretty explosions are seen high in the night sky.

Hunch would be something to do with high part counts, something like the physics calculations not being able to parse through every part in the window provided by a single update resulting in an accumulation effect.

Partial solution I found was to - immediately upon dock completing - exit to the space centre, from there head back into the tracking station and fly your newly docked contraption once more from there. Quitting direct control of the ship I guess nullifies all physics calculations allowing you to a return to a completely reset and stable ship.

[How to tell the terrain you're landing on?]

Don't forget to put some lights on your lander for when you need to land on the dark side, it's really, really difficult to judge your altitude, horizontal velocity, or any other quantity of interest without a tool like Mechjeb in those situations. The stock flashlight starts lighting up the ground at around 400 metres altitude, iirc, giving you plenty of time to do any necessary corrections.

Very much this. I tend to stick them on all landing craft. Slightly angled such that two spots converge as you descend, they give excellent visual feedback of altitude and descent velocity in anything other than the brightest of conditions.

A technique I practiced over and over again, umm, 30 years ago on a certain computer game. A game modelled on events 40 years prior to that so I guess the technique has been well proven by now.

[Space Planes]

I'm not very good at space planes yet but tips acquired thus far:

Action groups

Toggle jet engine(s) & intakes on/off in one action group.

Toggle rocket engine(s) in another.

Kill the jets just before flameout (keep a keen eye on the intake air resource) and light the blue touch paper on the rockets

Simulate mass distribution on re-entry

On the runway put the brakes on and burn off all your rocket fuel and half your jet fuel (throttle back a bit so as not to overwhelm brakes).

Then try to take off, fly around a bit and land some place - a fully laden plane can fly beautifully yet have the grace of a falling hippo once mostly empty.

Ideally centre of mass is just in front of the centre of lift & remains so despite fuel usage.

Don't launch like a rocket

Ie. don't just point at 45 degrees and see where that takes you.

Everything is governed by the intake air resource. If that's fine then keep on climbing.

If it's going too low too quickly then level off and try to pick up some horizontal velocity to get more air in the ram intakes, then try climbing a bit more.

When you think there's not much more left, make a final stab for the stars, killing the jet engines just before flameout and igniting the rockets.

Practice landing

A lot.

Ideally design planes with enough lift to take off and land at slow speeds.

[How useful do you find fueling stations?]

Moderator Edit Here you have a dancing elephant, courtesy r/gifs:

Yay Tuesdays can always be improved via the liberal application of elephants.

[How useful do you find fueling stations?]

I've not actually successfully docked anywhere yet so take all this with a pinch of salt. Have thus far only got to the Mun & back, Minmus & back, and Duna & well.... hmm... let's move on shall we?

I'm seeing the potential in Kerbin orbit stations not so much as refuelling stops but the place where you pick up your interplanetary stage tug.

If most designs end up having a launch>orbit stage, a nuclear-engined orbit>destination stage, and a destination payload/lander/return stage then we're constantly lugging very heavy nuke engines up into Kerbin orbit.

Rather than do that, why not put the payload directly atop the launch>orbit stage, use a bit of payload delta-v to dock with a station where it picks up an interplanetary stage consisting of one/two (if you're impatient) nuke engines and necessary fuel and replenishes the payload fuel used in docking?

A couple of nuke engines is 4.5 tons and that's quite a lot to haul from the Kerbin Space Centre every launch. The launch stage needs 20-25 tons less fuel if it doesn't need to carry those nuke engines up to orbit.

A handful of tug designs to accommodate different payload masses & destinations could be parked at a station, all equipped with a probe core, RCS and sufficient fuel to deliver the payload stage to it's destination then return to the station for refuelling and future use. The fuel for the interplanetary stage is, one way or another, always going to have to be hauled into orbit, whether in a single design or to a refuelling station; but the heavy engines - it could be worthwhile only hauling those up once and reusing them.

First post should really of been a grander entrance with explosions and dancing elephants.

Moderator Edit Here you have a dancing elephant, courtesy r/gifs: