Air Launch to Orbit in KSP - do you do it?

[glen.mack]

I was assessing the viability of air launch to orbit, but losing an aircraft every time in a stock career game probably puts most people off what is a very effective method of getting to orbit.

 

Do you use an air launch to orbit system in your non career games or are space planes the only way you do this?

 

[Rocket In My Pocket]

Cool video, but yeah doing in this in stock career would just get your plane promptly deleted which is a shame.

I realize the physics bubble is limiting but even if they "paused" the plane outside the bubble so you could fly it down after you were done with the rocket that would be a better system in my eyes. Perfect? No. Realistic? No. Better than not having any option at all currently? Yeah.

I'm sure someones gonna suggest the mod that auto retrieves stuff with enough parachutes etc... but that kind of robs the fun of actually flying the plane back down and landing it which from a game play perspective is the only reason I could see doing a launch of this style anyways.

[Foxster]

I find it tends to be better/easier/lighter to just have a 1st stage of jet engines and not bother with the wings and such to loft a smallish payload. 

[GoSlash27]

Air launch would be much more effective in KSP than in real life because flying speed is so much closer to orbital speed.

 But the physics bubble... Perhaps it will find a home once multiplayer rolls out.

Best,
-Slashy

 

[RizzoTheRat]

Interesting vid

For bigger stuff take a look at White Knight

Edited January 30, 2016 by RizzoTheRat

[suicidejunkie]

I recall seeing a video including a mod which would fork the savegame, and allow you to fly to orbit, then rollback to the separation point and fly the aircraft home.  Then it would merge the forks back together at the end so you'd have your plane on the ground and the probe in orbit at the same time.

I can't think of what it was called, or a proper search term to find it unfortunately.

[Hotaru]

14 minutes ago, suicidejunkie said:

I can't think of what it was called, or a proper search term to find it unfortunately.

FMRS, Flight Manager for Reusable Stages. I've never gotten it to work consistently, but I don't think I've tried it in 1.0.5 yet. If you did get it working it would open up all sorts of interesting possibilities: air launch, TSTO fully-reusable shuttles, flyback boosters, SpaceX-style first stage recovery, etc.

Honestly though, most of those things would be fun to do once but kind of a pain to do for every single launch in career mode when (in the stock scale-model solar system anyway) it's generally easier to just build an SSTO spaceplane or reusable rocket.

Edited January 30, 2016 by Hotaru
added link

[Snark]

I successfully did air launch (of a sort) in KSP for a little while, just for the heck of it, but I got tired of it pretty quickly once the novelty wore off.  Too much hassle.

It went like this:

I built a two-stage-to-orbit vehicle.  Bottom stage was a whole bunch of Whiplashes -- I think I used a 2.5m stack, with four underneath on a quad coupler, and eight more radially attached around it, so like a dozen altogether.  Shock cone intakes for all the radially attached engines; some extra radial intakes tacked on for more air supply for the ones underneath.  Top stage was a conventional rocket.

1. Take off vertically from the launchpad using the turbojets.  Do a fairly standard-looking gravity turn (a bit shallower than usual, to give the turbojets more atmosphere time).
2. Right at the top end where the jets are pooping out, it's on a trajectory that's steeper than a typical spaceplane, but shallower than a typical LFO rocket.  It's going at top Whiplash speed, and coasting upwards with an Ap pretty high in the upper atmosphere.
3. Then stage.  (Crucially, we're already well above 23 km, which is the magic limit below which KSP would automatically delete an untended craft outside the physics bubble.)  The upper rocket stage does a burn that's enough to lift its Ap up to the desired circular-orbit height.
4. Switch back to the jettisoned 1st stage, which has a probe core on it to keep it controllable.  Follow it as it plummets down to the surface, pop chutes to do a soft landing and recover.  The 1st stage touches down before the 2nd stage reaches Ap.
5. Switch back to the 2nd stage before it reaches Ap.  Do a circularization burn as per usual.

It actually worked pretty well.  I got tired of it pretty quickly, though, for a couple of reasons:

• It was tedious.  Babysitting the spent 1st stage back to earth was just dull.  Flying a rocket this way just meant I had to take twice as long (in terms of my time) to get to orbit, and the extra time was spent in uninteresting drudgery.
• It broke immersion for me.  It's a silly way to launch a rocket.  Nobody would ever do this in real life; the mission design is a hack workaround to KSP's game limitation that you can only fly one craft at a time.  Any time I find myself doing something in-game that makes sense only in terms of its architectural limitations, it's vaguely annoying to me.

 

Edited January 30, 2016 by Snark

[glen.mack]

1 hour ago, suicidejunkie said:

I recall seeing a video including a mod which would fork the savegame, and allow you to fly to orbit, then rollback to the separation point and fly the aircraft home.  Then it would merge the forks back together at the end so you'd have your plane on the ground and the probe in orbit at the same time.

I can't think of what it was called, or a proper search term to find it unfortunately.

I do mention this actual mod, Flight Manager in the video, by name.

[Evanitis]

Dang. I always wanted to do something like this since I saw this picture:

It actually got me back to KSP after some hiatus. Of course that was before I watched a lot of space exploration documentaries, so I didn't know it's not an actual way to launch the Shuttle.

Though not much later I discovered what are SSTO spaceplanes, and forgot everything else while I built a few. Now it's time to do a plane-launch! Though I guess I won't be bothered by grabbing the mod for the extra hassle of landing the host craft. I tend to not lower the funds income slider enough, so I always find myself sitting on piles of cash to burn for silly projects. Like that one.

[wumpus]

There are two problems with airlaunch with unmodded KSP:

First, once you leave the "physics bubble", you aircraft is deleted.  Your launch vehicle either becomes a spaceplane or becomes single-use.  Most kerbalnauts prefer to make their spaceplanes SSTO the payload as well.  Note that there is a great mod for this (which might not work with 1.0.5 or be updated): http://kerbal.curseforge.com/projects/fmrs-v1-0-01

Second, all the air-breathing engines in KSP are OP.  If you really want understand the issues with air-launches, you will likely need realism overhaul (and the mod listed above to reuse your airplane).

If you don't want *any* mods, there is a quick and dirty way to get around this:  build a first stage with solid rocket boosters that will burn with lots of thrust and a short burn time.  You are looking for less than 500m/s of delta-v (less than 250 if you don't have drogues or otherwise want to make things easy on yourself).  The trick involves the much larger "physics bubble" of 1.0.5 (or thereabouts) compared to earlier editions.  WARNING: I am still working on this idea.  Its more a side project that hit me when learning about the physics bubble change.

NOTE: the following has NOTHING to do with air launch (aside from reusing the booster that eats most of the atmospheric drag), and has everything to do with not paying for the last (well first, but we build rockets back to front for a reason) 200-500m/s needed for orbit.

Step 1: add a solid stage that will provide no more than ~500m/s of delta-v and will get there well before 10,000m.

Step 2: slow the thing down.  This could mean strapping flea rockets upside down to reverse thrust (and will be needed for extreme attempts at this).  Add drogue chutes.  These will slow down your booster and survive at 500m/s.  Note that if you use flea rockets you are likely going to require "upside down" fins (but presumably the COM will be well above them.  Put fins on the first stage and make sure they are below the COM as well).

Step 3: make sure your chutes survive [UNTESTED].  Set the "partial deploy" altitude as low as possible.  You need the drogue to slow the thing down to 250m/s or the main chute will not survive.  You also need the chute to go fast enough toward the ground to get there before the main rocket goes over 22km.  This means more aggressive rockets have to stage well before 10km.

Step 4: Make sure all stages (decoupler, retrorockets, drogue, chute) fire at once (you lose control of it after you stage it).  If you are using landing gear, deploy that first (it probably won't make a difference if you deploy it on the pad).

Note that there are two options.  Pad landing and sea landing.  Pad landing is straight up and requires gear, but give 100% returns.  Sea landing allows a pitchover (gravity turn) and puts you on course for the next stage.  I'd recommend the sea landing, especially if you are trying for higher speeds (which will have less control.  Note that horizontal distance counts, so don't lose your rocket because it is 10km up but 20km down stream...

Finally, don't be afraid to make both stage-0 and stage-1 solid rockets.  They might not be the most efficient by mass, but they are often wildly more efficient by price (especially stage-1 which isn't coming back).  This doesn't impart enough delta-v to support the "don't lift solid rockets into space" rules.  Liquid might work best, or solid might work best.

[Reactordrone]

I've done an aircraft launched satellite just for the novelty but it's not easy to land the launch aircraft quickly enough to switch back to the probe for the circularisation burn.

Edited January 30, 2016 by Reactordrone

[Wjolcz]

I would if NeverUnload went stock. I really enjoy designing aircraft and using them for LKO payloads could be a fun thing to do.

[Overland]

Was it in one of the james bond films where someone fired engines of a piggybacked shuttle from a 747 and took off into space? 

(747 didnt survive .destroyed by shuttle main engines)

Yup...looked it up but probably not nice to post here..look up moonraker shuttle launch or hijack

 

10 hours ago, Evanitis said:

Dang. I always wanted to do something like this since I saw this picture:

It actually got me back to KSP after some hiatus. Of course that was before I watched a lot of space exploration documentaries, so I didn't know it's not an actual way to launch the Shuttle.

Though not much later I discovered what are SSTO spaceplanes, and forgot everything else while I built a few. Now it's time to do a plane-launch! Though I guess I won't be bothered by grabbing the mod for the extra hassle of landing the host craft. I tend to not lower the funds income slider enough, so I always find myself sitting on piles of cash to burn for silly projects. Like that one.

 

Edited January 31, 2016 by Overland

[Edax]

It's really just easier to build an SSTO that can lug the other ship all the way into orbit.  Then you can land both ships separately whenever you have the time.  (Picture was taken in 1.0.4 when you needed an intake for every engine).

Granted, you will need LOTS of engines to overcome the huge amount of drag carrying a second ship will cause, but who doesn't want to build a 17 engine super-plane?

Edited January 31, 2016 by Edax

[Evanitis]

6 hours ago, Edax said:

It's really just easier to build an SSTO that can lug the other ship all the way into orbit.

"We don't launch stuff from planes and do the other things because it's easy, but because we are very stupid."

Had my fist attempt yesterday. Though I wanted to do it STS style, so the carrier plane's main fuselage carries rocket fuel and engines, and only ditches the turboramjets and the wings. The shuttle carries Inigma's 42t standard STS fuel pod as payload (it's LF/O is locked of course). I managed to reach orbit on the first try (well, actually on the first try when I managed to lift off). Though when I detached the useless jet parts, the shuttle wings broke off too, so I had to abort the mission. Also I had some strange engine-damage: the 6 vectors didn't stop burning when I cut the throttle, so the craft went for a highly elliptical and eccentric orbit.

Yes, a standard SSTO plane would have been easier. Hell, I felt it would have worked if I just didn't stage anything. But it looks cooler this way.

We'll have a quick rescue mission today, and off to perfect the design.

[John FX]

I do because I use stagerecovery so I don`t get the hit to funds from losing a resusable vehicle. I just slap a few chutes on it and bingo. Or I leave enough fuel and a probe core and it simulates a powered landing.

EDIT :I also don`t have to babysit the spent stage all the way down which removes the grind.

Edited January 31, 2016 by John FX

[Yakuzi]

15 hours ago, Veeltch said:

I would if NeverUnload went stock. I really enjoy designing aircraft and using them for LKO payloads could be a fun thing to do.

It's a shame that mod was discontinued, you could leave your carrier in the atmosphere with SAS on while getting your spacecraft in orbit, then come back and land your carrier.

kOS seems to have an option to increase the 'physics bubble' as well, if I understand the relevant documentation correctly. However, I haven't had the time to play around with it... has anyone else tried? (I also heard BDArmory can extend the unloading range).

Edited January 31, 2016 by Yakuzi

[katateochi]

3 minutes ago, Yakuzi said:

(I also heard BDArmory can extend the unloading range).

yeah it increases it to 5km IIRC.  The Romfarer lazor system mod also increased the range and had a GUI setting for adjusting it....is that mod still alive btw?

[moogoob]

I made a little Virgin Galactic-style suborbital hop plane once... I didn't prefer it over a normal launch, but the benefits of being able to use more efficient engines in the high atmosphere IS tempting. The problem I found was getting that combo of TWR and efficiency that makes air launch into an actual orbit useful. Ended up just using a Thud clipped into the craft, for TWR reasons.

That said, for a suborbital hop it's a fun little flight, and I can see why space tourists are wanting to plop down six figures.

[eurybaric]

I really enjoyed that video. Very informative.

Cheers!

[wumpus]

15 hours ago, Overland said:

Was it in one of the james bond films where someone fired engines of a piggybacked shuttle from a 747 and took off into space? 

(747 didnt survive .destroyed by shuttle main engines)

Yup...looked it up but probably not nice to post here..look up moonraker shuttle launch or hijack

 

 

Even James Bond (or a Bond villain) couldn't get the SSMEs to light without the fuel tank added.  On the other hand, I'd bet that the OMS would be even brighter (and have more exhaust) than what's shown (although with only two engines, I'd be shocked if they were in those positions).  I'd hope they [NASA] drain the OMS fuel (it's hypergolic) before sending it back, but presumably some Bond villain minions prevented that from happening.

[Overland]

Could work in KSP but youd need to trade fuel for cargo bay.. Likely not get to orbit but youd have the plane destroyed by the engines in an epic bond-like launch... Perhaps thats a good challenge... Most authentic moonraker hijack launch challenge!

[glen.mack]

8 hours ago, Overland said:

Could work in KSP but youd need to trade fuel for cargo bay.. Likely not get to orbit but youd have the plane destroyed by the engines in an epic bond-like launch... Perhaps thats a good challenge... Most authentic moonraker hijack launch challenge!

Visually, you'd need something like B9's aerospace pack or something to give you an authentic looking passenger jet, beyond that, this would be super easy.

[RizzoTheRat]

8 hours ago, Overland said:

Could work in KSP but youd need to trade fuel for cargo bay.. Likely not get to orbit but youd have the plane destroyed by the engines in an epic bond-like launch... Perhaps thats a good challenge... Most authentic moonraker hijack launch challenge!

That would solve the issue of not being able to recover the aircraft without mods too