In-flight Refueling difficulties!

[Vigelius]

Hi All!

I've got a fun little project going on here, and its got so close to success that I don't want to give up now - I'm in desperate need of someone who knows about aeroplane design!

So as the title suggests, I'm trying to dock two planes in atmospheric flight. As you might expect, that presents a few challenges:

Issue #1 - To dock two planes, I need to have two planes! But when I try to put something on the runway from the SPH or main KSC screen, it clears off anything already there. Simple solution, taxi the chase plane onto the grass first.

Issue #2 - As soon as I'm in flight, the game won't allow me to switch focus. It will let me switch to any pieces of falling debris though. I've got a docking port on the back of my lead plane anyway, so I attach an unmanned probe body and basically try to bomb the second plane with it. Tab to the debris as it falls, and then switch planes that way.

Issue #3 - Whilst the lead plane is still flying, any attempt to switch between craft results in going straight back to it and then Issue #2 kicks back in. I replace the probe body with a lander can, stick a parachute on it and drop the altitude of my flypast as low as possible. The idea is that any craft a Kerbal enters from EVA immediately becomes the active vessel. A free crew slot and an access ladder are necessary on the chase plane.

Issue #4 - Getting a parachute involved means that by the time the can hits the deck and the pilot jumps out, the plane that dropped it has flown 2.5km away and vanished. Lazor Systems' docking mod on full draw distance only actually seems to increase that to 4.5km, which is still not enough. TTNeverUnload comfortably fixes the problem (reusable rockets here I come! No, stick to the task in hand...)

Issue #5 - Kerbals walk really slowly! By the time the pilot is ready to go he's got 45km to close up, even with the lead plane at minimum throttle. That means the chase plane has to be rapid! The trouble with that is we end up with a twitchy plane, which needs to go at high speed to have half decent control authority. But at high speeds, the tiniest manouevres cause all sorts of wobbling and careering about that just isn't compatible with docking. I could make an edited version of the lead plane to serve as the chase plane so we can slow things down a lot, but the massive wings mean we just run into the same un-subtle manouevre problem at lower speeds.

Beyond "be a better pilot", does anyone have any ideas?

EDIT: After running through some tweaks, now going to learn how to be a better pilot!

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Mods Used:

B9 pack

Ferram Aerospace Research

Lazor Systems' docking cam

TTNeverUnload

Edited April 24, 2014 by Vigelius

[Aphobius]

No cheats

I don't refuel it, but I could have done it.

EDIT: To be honest "be a better pilot" is the best tip. Kerbal is not really something serious xD. But air refueling is usually hard to do anywhere.

Other than that, I don't know how that FAR thing is working, but I had to remove the control surfaces from the aircraft that I'm controlling while docking, so it doesn't accelerate anymore when I control it. (because of that infini-glide crap)

Edited April 19, 2014 by Aphobius

[Nemecle]

You can try to take off with one plane attach on the other, make "control from here" on the small one and then ditch it : you get away a bit from the tanker and then get closer by behind and try to dock

[Claw]

I've launched the second aircraft airborne before, but haven't tried on the ground yet. Airborne launches seem to work okay, but I'm not sure that'll work for your config.

Edited April 19, 2014 by Claw

[Dust]

Issue #5 - Kerbals walk really slowly!

I discovered quite recently that Kerbals run if you hold down shift...

[Rokker]

You could look into Burn Together http://forum.kerbalspaceprogram.com/threads/75170-WIP-Plugin-(0-23-5)-Burn-Together!-Alpha-v3-available-(4-10-14)

[Vigelius]

@Aphobius - Good skills! Couple of things:

- How did you get around the active craft problem? You just seem to tab across when you fly over, but mine won't let me do that

- Have you got mods on that? I don't recognise the shielded docking ports

- How do you keep the wings so stable on the big plane with so few struts?

- I'm quite new to FAR, but from what I've seen it is a massive improvement to the aerodynamics. Certainly infini-glide isn't a problem. It slows down a lot through manoeuvres, which makes more sense to me.

You can try to take off with one plane attach on the other, make "control from here" on the small one and then ditch it

I tried that with these builds, but with the extra power in the chase-plane it kept catching up and jackknifing the whole setup. Might work better with a smaller chaser...

I've launched the second aircraft airborne before

Does this mean the same thing as Nemecle? Launch them as though they are one craft and then split it?

I discovered quite recently that Kerbals run if you hold down shift...

Good knowledge!

@Rokker - Burn Together looks pretty sweet! Unfortunately it doesn't seem to do so well in atmospheres (yet!)

[Claw]

Yes, I mean the same thing. If your chase plane is too powerful, use tweakables to lower the thrust output for takeoff. Docking ports are fairly strong when pulling, so it's probably better to slightly undershoot with the thrust and let the tanker do most of the pulling.

I did try switching between craf with one on the ground like you're asking about but was unable to. I really thought I used to be able to do that in 0.23.0 but it seems really finicky now 0.23.5. I will try it in 0.23.0 later and see.

Edited April 20, 2014 by Claw

[Claw]

Ahh, here is an example of one of my dual craft configs. Although this is piggyback style.

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[Aphobius]

@Aphobius - Good skills! Couple of things:

1 How did you get around the active craft problem? You just seem to tab across when you fly over, but mine won't let me do that

2 Have you got mods on that? I don't recognise the shielded docking ports

3 How do you keep the wings so stable on the big plane with so few struts?

4 I'm quite new to FAR, but from what I've seen it is a massive improvement to the aerodynamics. Certainly infini-glide isn't a problem. It slows down a lot through manoeuvres, which makes more sense to me.

I tried that with these builds, but with the extra power in the chase-plane it kept catching up and jackknifing the whole setup. Might work better with a smaller chaser...

Does this mean the same thing as Nemecle? Launch them as though they are one craft and then split it?

Good knowledge!

@Rokker - Burn Together looks pretty sweet! Unfortunately it doesn't seem to do so well in atmospheres (yet!)

I modified your quote a little, to add numbers to the questions.

1 - It works if you are under 250m from the target (not sure if it's exactly 250m, but if i remember right it's not working at 500m)

2 - They are default parts.

3 - There are few struts, but placed in the proper places.

4 - As I've said, I don't know how FAR is working, if airplanes are slowing down too much when you maneuver that is also a problem.

[Vigelius]

So after a bit of experimentation there is progress:

- I can confirm that tabbing directly to a craft on the ground works from below 250m

- I removed FAR and that made everything waaay easier for two main reasons:

i. The atmosphere is much thinner with FAR, so without it craft stay in the air at about half the speed

ii. Everything with wings is much less responsive without FAR, so close manoeuvres are a lot more forgiving.

- Interesting learning about tiny planes which only have one pair of canards as control surfaces. Seems weird to me!

- I'm still struggling to seal the deal, but that's clearly just my bad piloting now!

Thanks for all your help folks!