In-Flight Refueling

[NASAHireMe]

Just out of curiosity, has anyone completed a mid-air refueling? Imagine deorbiting a tank, sticking a gajillion parachutes on it so the descent rate is very slow, then flying another plane, rendezvous, docking, and refueling, all before the tank crashes into the ground. Then take that plane into orbit.

If there's enough interest I might make this into a Challenge.

Edited April 10, 2015 by NASAHireMe

[Pecan]

Yes, in-flight docking has been done a few times.

Only a few times though because of the restrictions on the physics bubble (2.5km but changing in 1.0 apparently) and not being able to change vessel while in atmosphere.

[Mister Dilsby]

If there's enough interest I might make this into a Challenge.

Extreme Madness Level could be to dive a ship into Eve atmosphere and refuel an ascending lander, giving the latter just enough dV to orbit.

[Michaelo90]

Extreme Madness Level could be to dive a ship into Eve atmosphere and refuel an ascending lander, giving the latter just enough dV to orbit.

That's completely insane! I like it

[thadisjones]

This might be quite doable with the Hooligan aerostat mod and probably isn't any more a "physics exploit" than slapping five dozen noclip parachutes in a tiny area. But that physics bubble and atmospheric control switching is still going to be a tricky thing.

Oh, the problem with both aerostats and the parachute tank re:spaceplane resupply is that in order to dock with a floating or slowly dropping refueling point, you have to lose most or all of your horizontal velocity that you paid for to get to that point, and depending on how thin the air is and the design of your spaceplane, you might not be able to get it back without a horribly inefficient altitude loss. I don't see this ever being a good idea (in mostly-stock) compared to orbital refueling, where you get to keep your orbital velocity and you can detach without plummeting towards the lithosphere.

Remember, that's the reason (ok, one of the reasons) IRL why jet fighters refuel from jet tankers, and not fuel blimps or the tops of really tall towers.

Edited April 8, 2015 by thadisjones

[Mister Dilsby]

Oh, the problem with both aerostats and the parachute tank re:spaceplane resupply is that in order to dock with a floating or slowly dropping refueling point, you have to lose most or all of your horizontal velocity that you paid for to get to that point, and depending on how thin the air is and the design of your spaceplane, you might not be able to get it back without a horribly inefficient altitude loss.

Exactly. I guess I'm thinking this direction because of my still-in-progress Eve Rocks attempt. (http://forum.kerbalspaceprogram.com/threads/115007-Operation-Big-Purple-just-ONE-more-v0-90-mission-to-Eve) My ascender should work just fine, but what if it just doesn't deliver enough thrust/deltaV? Imagine if it can't do better than lob the capsule out of atmosphere, in a suborbital trajectory. Could I decelerate the orbiting mothership to intercept the capsule, catch it in the cargo bay, and then blast back to a stable orbit before all 150 tons of KSS Wasabi Maru ends up scattered across the purple fruitless plains of Eve? Probably not--but OMG that would be an epic save.

Edited April 8, 2015 by Mister Dilsby

[thadisjones]

lob the capsule out of atmosphere, in a suborbital trajectory. Could I decelerate the orbiting mothership to intercept the capsule, catch it in the cargo bay, and then blast back to a stable orbit

I've tried this as a means to get fuel cans into orbit. To make something easily catchable without intensive precomputation (that is, catching it by being more or less in the right place by eye and then jiggling maneuver nodes), it must be in a high, wide arc. And if you can do that, it means you probably are close to achieving a stable orbit anyway, by adopting a more efficient ascent trajectory.

[Xavven]

Exactly. I guess I'm thinking this direction because of my still-in-progress Eve Rocks attempt. (http://forum.kerbalspaceprogram.com/threads/115007-Operation-Big-Purple-just-ONE-more-v0-90-mission-to-Eve) My ascender should work just fine, but what if it just doesn't deliver enough thrust/deltaV? Imagine if it can't do better than lob the capsule out of atmosphere, in a suborbital trajectory. Could I decelerate the orbiting mothership to intercept the capsule, catch it in the cargo bay, and then blast back to a stable orbit before all 150 tons of KSS Wasabi Maru ends up scattered across the purple fruitless plains of Eve? Probably not--but OMG that would be an epic save.

Hmmm. I think you've given me a project to work on while I wait for 1.0! I'm going to build an Eve ascent vehicle that is not designed to orbit, but rather shoot straight up (pure radial burn) in order to be caught by an orbiting "skyhook". The skyhook will have to slow its orbit to 0, catch the freefalling ascent vehicle, and then return to orbital velocity.

BWAHHAHAHAHA!

[Xavven]

Wow... it's waaay harder than I thought it would be. I've just been practicing on Kerbin. Getting the timing down is horrendous. But what really makes it hard is that you can't switch vessels in the atmosphere. Meaning... I can't start my skyhook's deorbiting/rendezvous burn until my ascent vehicle is already close to its apoapsis. This results in the rendezvous occurring while the ascent vehicle is falling back to the surface, making it unrecoverable

I did manage to dock while re-entry flames were shrouding both vehicles, though. Hah!

[ilo]

yay.. and once you dock you don't even have time to think on what is coming next.. land lol

#14752

It is quite tricky, you have to keep your relative velocity while atmosphere drag slows you down from the target (or the contrary).. I still have this sfs save kept safe