Any reason to make planes and fly them?

[Unknow0059]

I'm talking about both kinds of planes, the space one and the air one, they are slow as truck from what i have tested, and i can get to other biomes easily with rockets so why would i make a plane?

Edited November 11, 2014 by Unknow0059

[Starman4308]

A, if you like planes.

B, if you care about cost efficiency: an SSTO spaceplane is far more efficient than a rocket.

C, if you want to biome hop on Kerbin without a single non-enormous vehicle.

D, if you want to explore places like Duna and Eve from within the atmosphere in short time-frames.

[sal_vager]

Why not? Why miss out on the fun of something like this

[Starwhip]

They make "in atmosphere" flying contracts much, much easier. And if you don't drop parts, which on a plane is very rare, they return nearly all funds put into them (except fuel).

I use them to test bits and bobs that come up in Mission Control when I've got nothing better to do.

[Wjolcz]

Depends if you are playing Sandbox or Career.

In sanbox you don't have to care about that, but if you want some extra cash you want to re-use your crafts. And SSTOs are great for that. Not much payload, but can perform many science experiments in that bay! Also the "Fine Print" mod gives a whole lot of air recon missions, in which you want to use planes, since they are way easier to fly at a certain altitude.

[Unknow0059]

You guys here on the forums answer really fast

Anyway thanks for the answers!

[Raptor9]

Besides fun? In all seriousness, in career mode spaceplanes (if designed and flown right) have the advantage of reducing overhead costs. For example, to launch a satellite in orbit, you would have to buy and throw away a launch vehicle. But with a spaceplane, you can take off from the runway, fly to the orbit you want the satellite in, simply decouple it from the cargo bay using a small docking port, and then return and land at the runway. The only thing you end up paying for is the fuel the spaceplane expended, you get reimbursed for the rest. Plus, the satellite itself is cheaper since you didn't have to put a small orbital maneuvering rocket and fuel tank on it to get that perfect orbit; and the satellite is usually is worth more than a second fuel load for the spaceplane, so if you take the time to recover it when its mission is complete, you get money back for the satellite.

I recently inserted a small Scansat that consisted of nothing more than a probecore, a battery, a couple small solar panels, and a scanner in 250km polar orbit using a spaceplane. Designing other aircraft that test flying wing, lifting body, canard-delta vs wing-tail layouts, etc. can show you various techniques for optimizing your aircraft/spaceplanes for specific missions.

EDIT: SNIPED! While I was typing a tangent, these other fine individuals already answered.

Edited November 11, 2014 by Raptor9

[Starwhip]

You guys here on the forums answer really fast

Anyway thanks for the answers!

Glad to help.

(We really do, don't we?)

[Wanderfound]

Did somebody mention "slow"?

[Alshain]

Reason: Fun

You need more?

[cantab]

True, a ballistic rocket will generally be quicker than a plane for either a trip around Kerbin or getting to orbit. The difference, however, need not be all that much. Fast high-altitude jets can get you around Kerbin quite quickly enough. For making orbit, there's often a tradeoff between fuel and time, and there's not really much need to squeeze every last bit of speed out of the jets like some players like doing, you can just do enough that the rockets handle the orbital insertion. Runway to orbit in five or six minutes is reasonable.

[Wanderfound]

True, a ballistic rocket will generally be quicker than a plane for either a trip around Kerbin or getting to orbit. The difference, however, need not be all that much. Fast high-altitude jets can get you around Kerbin quite quickly enough. For making orbit, there's often a tradeoff between fuel and time, and there's not really much need to squeeze every last bit of speed out of the jets like some players like doing, you can just do enough that the rockets handle the orbital insertion.

Incidentally, from the challenge threads: the current spaceplane runway-to-70x70orbit speed record stands at about three and a half minutes. Runway-to-orbit-to-runway is about fifteen minutes.

Those are all genuine jet-powered winged spaceplanes, not finned missiles.

See http://forum.kerbalspaceprogram.com/threads/94343-Spaceplane-Speed-Challenge-IV-Up-and-Down and http://forum.kerbalspaceprogram.com/threads/90354-Spaceplane-speed-challenge-shortest-elapsed-time-from-runway-to-orbit

[capi3101]

Folks have generally covered the reasons to use planes versus rockets, so I'll just expound a bit on the efficiency front. A well-designed asparagus-staged rocket usually has a payload fraction of somewhere in the neighborhood of 15-18% give or take, this for a vehicle whose only parts might be recovered would be a portion of the payload (if that - if the payload is a satellite, you're not getting any money back for the parts at all). A crappily-designed transporter spaceplane will generally have a payload fraction around 25%, which is the figure I use when I design my planes. That particular lift vehicle can be recovered intact - you will recoup at least some of the cost of the parts when the plane lands (provided you don't botch the landing, of course); land it at the KSC runway or its environs and you'll get a 100% refund. So in that case, you get most of your money back - which makes a plane as a booster vehicle way more cost effective.

Naturally, planes are way trickier to design and fly than rockets are. Fortunately, there are guides to help with both the design and piloting aspects. I generally point spaceplane newbs to two places - Keptin's Basic Aircraft Design Explained - Simply with Pictures post (a great place to begin) and to DocMoriarty's KSP Space Plane Construction and Operation Guide (a great place for specifics and ideas on what exactly you can do with planes).

[KerikBalm]

... SSTOs are great for that. Not much payload, but ...

I beg to differ:

0.23 all stock (some non stock payload parts, but lifter is stock):

0.24 with SpacePlane+ addon and NEAR (Payload is additionally modded, adaptors and nosecones into fuel tanks, large xenon tanks)

I don't have an pics of my 0.25 Stock-ish space plane with FAR (stock-ish because of FAR, and also because I have modden nosecones and adaptors that are fuel tanks)

That one I just got to orbit with 154 tons of Liquid Fuel + Oxidizer left over.

I get payload fractions of nearly 50% with my planes.

For some odd payloads, they are easier to launch than rockets, for other payloads, a rocket is much easier.

This is particularly true in NEAR/FAR. In soupy stock atmo, the payload doesn't affect the overall aerodynamics of the vessel all that much.

Edited November 11, 2014 by KerikBalm

[mdkendall]

... if you don't drop parts, which on a plane is very rare ...

Say what now?

[Zylark]

If playing with mods such as Stage Recovery or DebRefund, the cost of launching a rocket isn't all that great. You get back about 80-90% of the cost provided you've slapped enough parachutes on your lifters.

What I find SSTO Spaceplanes useful for is transferring crew and various supplies and small payloads to and from LKO. My Spaceplanes at least have quite modest cargo-capability. If I try to go big, the part count alone puts me into the single digit framerate, making the things impossible to fly.

The great benefit of Spaceplanes is the obvious, only cost is fuel. The downside is that they require constant baby-sitting. From take off to landing. Which if a lazy MJ (ab)user like myself can get a bit tedious... They're fun to design and tinker around with though. Making one that handles well _and_ gets to orbit is almost an achievement in itself.

[MarvinKitFox]

I'm talking about both kinds of planes, the space one and the air one, they are slow as truck from what i have tested, and i can get to other biomes easily with rockets so why would i make a plane?

With one plane, you can go visit ALL biomes on Kerbin in one launch.

(Ok, I usually don't bother with Badlands, it is on the other side of the planet after all)

Land at each, do all your repeatable science, etc.

Rockets get there faster, and in many cases easier.

But you would be hard pressed to do even 4 biomes from one launch.

In addition, rockets tend to drop very valuable parts all over the place. Very expensive!

With a plane, you can launch, land multiple times, and return to base. Your only expense is the fuel used. And some time

[DrMonte]

Edited November 12, 2014 by DrMonte

[rodion_herrera]

Because I love flight simulators too, and I own several joysticks. I love flying KSP aircraft and spaceplanes with a joystick, it makes takeoffs, landings, and various maneuvers easier. I have a custom kludge-HOTAS setup involving two joysticks and a gamepad for KSP aircraft.

[Pecan]

Apart from the fun there are exactly TWO reasons to build planes (in atmosphere and with stock parts) - i) horizontal flight capability makes it easier to land wherever you want to, ii) lift from wings means it is possible to take-off with TWR<1.

PLANES are not at all more efficient than rockets, JETS are more efficient than rockets.

PLANES are less efficient than VTVL jets, because they have all that wing/gear mass and drag.

[Alshain]

Apart from the fun there are exactly TWO reasons to build planes (in atmosphere and with stock parts) - i) horizontal flight capability makes it easier to land wherever you want to, ii) lift from wings means it is possible to take-off with TWR<1.

PLANES are not at all more efficient than rockets, JETS are more efficient than rockets.

PLANES are less efficient than VTVL jets, because they have all that wing/gear mass and drag.

But planes have lift, with a VTVL you have to have a TWR of 1+, with a plane you do not (as you yourself mentioned). Therefore VTVL with jets end up consuming more fuel from simply having more engine to get higher thrust. I disagree with the statement that VTVLs are more efficient because of less mass because efficiency isn't just about the mass. Not to mention engines add a considerable amount of mass themselves, and since you need more of them that is a double whammy.

Edited November 12, 2014 by Alshain

[Pecan]

But planes have lift, with a VTVL you have to have a TWR of 1+, with a plane you do not (as you yourself mentioned). Therefore VTVL with jets end up consuming more fuel from simply having more engine to get higher thrust. I disagree with the statement that VTVLs are more efficient because of less mass because efficiency isn't just about the mass. Not to mention engines add a considerable amount of mass themselves, and since you need more of them that is a double whammy.

Many, probably most, flight-simulator fans would agree with you and in FAR I can imagine it makes more difference but in stock at least wings do almost nothing to help a spaceplane get high, and obviously don't do anything for 'fast'. A VTVL doesn't use high thrust 'just' to take-off (and let's not argue that 1 is 'high') but to accelerate quickly. There are a lot of variables, of course, and I'm nowhere near the best spaceplane (SP) designer or pilot around, but my 'standard' SP ascent is 0-pitch on runway, 40-50 degrees to 10-15km, 20-30 degrees to 20km, reducing to 0-degrees at 25-30km. In contrast my standard VTVL ascent is 90-degree pitch on launchpad to 500m-1km, 40-50 degrees to 10-15km ... and then exactly the same.

In practice, how low are you going to go with your SP's launch TWR? Probably not ever much below 1 because then you won't have enough thrust for speed at altitude. Aiming for 1.2? Sounds like an ideal FAR vertical-launch TWR. For the record: also in practice, I think the mass of wings and gear ARE worthwhile - but specifically for the landing, not take-off, ascent or fuel-efficiency (this isn't something I say very often because there are always so many people shouting about how great SPs are and not thinking about or listening to the contrary points).

ETA: 1 turbojet, FL-T100 fuel tank, oxidiser removed and LF tweaked to 40 units and Ram intakes is a 1.6t VTVL launch-vehicle for a detachable 4t payload. It has a launch TWR >2.5 because, well, you can't have half a turbojet! How would wings and gear help, given that it is intended to be disposable?

Edited November 12, 2014 by Pecan

[Alshain]

Many, probably most, flight-simulator fans would agree with you and in FAR I can imagine it makes more difference but in stock at least wings do almost nothing to help a spaceplane get high, and obviously don't do anything for 'fast'. A VTVL doesn't use high thrust 'just' to take-off (and let's not argue that 1 is 'high') but to accelerate quickly. There are a lot of variables, of course, and I'm nowhere near the best spaceplane (SP) designer or pilot around, but my 'standard' SP ascent is 0-pitch on runway, 40-50 degrees to 10-15km, 20-30 degrees to 20km, reducing to 0-degrees at 25-30km. In contrast my standard VTVL ascent is 90-degree pitch on launchpad to 500m-1km, 40-50 degrees to 10-15km ... and then exactly the same.

In practice, how low are you going to go with your SP's launch TWR? Probably not ever much below 1 because then you won't have enough thrust for speed at altitude. Aiming for 1.2? Sounds like an ideal FAR vertical-launch TWR. For the record: also in practice, I think the mass of wings and gear ARE worthwhile - but specifically for the landing, not take-off, ascent or fuel-efficiency (this isn't something I say very often because there are always so many people shouting about how great SPs are and not thinking about or listening to the contrary points).

ETA: 1 turbojet, FL-T100 fuel tank, oxidiser removed and LF tweaked to 40 units and Ram intakes is a 1.6t VTVL launch-vehicle for a detachable 4t payload. It has a launch TWR >2.5 because, well, you can't have half a turbojet! How would wings and gear help, given that it is intended to be disposable?

Well sure it's really easy to say it's more efficient if you keyhole it into one specific scenario where it has to be disposable and can't carry more than 4t payloads. You didn't say that though, you flat out said VTVL are more efficient than planes. I can see how FAR might make a bigger difference but even in stock there are cases where it isn't true.

[Pecan]

Well sure it's really easy to say it's more efficient if you keyhole it into one specific scenario where it has to be disposable and can't carry more than 4t payloads. You didn't say that though, you flat out said VTVL are more efficient than planes. I can see how FAR might make a bigger difference but even in stock there are cases where it isn't true.

Same thing with an 8t payload and the whole 45-units fuel, chutes for recovery. I could give other examples across payload masses but I think Stratzenblitz75 does about the nicest.

Counter-example where a plane benefits from wings on the way up? I'd be happy to be proved wrong; it's how we learn.

[Alshain]

Same thing with an 8t payload and the whole 45-units fuel, chutes for recovery. I could give other examples across payload masses but I think Stratzenblitz75 does about the nicest.

Counter-example where a plane benefits from wings on the way up? I'd be happy to be proved wrong; it's how we learn.

It's still keyhole'd to say "on the way up". You keep adding conditions to your original statement after the fact. One of the best parts of planes is the ability to glide back down unpowered for a full recovery. No fuel spent after de-orbit. Let's see you land a VTVL on the runway without using fuel after deorbit. That would actually make a really good challenge 'cause I'm sure it CAN be done with the right combination of skill, luck, and parachutes... but realistically it's not going to happen most of the time.

I don't disagree with you that in certain conditions and purposes that a VTVL would be more efficient. I'm not disagreeing with your new statements, I disagreed with the original one which said "PLANES are less efficient than VTVL jets, because they have all that wing/gear mass and drag." and by lack of further definition or clarification implies that is ALWAYS the case in ALL conditions. That is what I disagree with.

Edited November 12, 2014 by Alshain