What's The Difference in Wings?

[sardia]

How exactly do the wings differ? Like if I have multiple small wings, is that the same as 1 bigger wing? And if wings are all equal, is carrying fuel in the wings just as good as carrying fuel in the fuselage?

Or is there a progression of better* wings as you progress up the tech tree? Googling wing analysis doesn't reveal much, except for an old reddit thread not to angle my wings up or down.

*better defined as most lift given per weight used, and least drag added.

[The_Rocketeer]

Wings all have different lift, drag and mass ratings. The best all round wing (most lift for least drag and mass) was the Wing Strake, but that was based on a couple of versions ago.

Fuel in the wings affects CoM in different ways depending on how you mount the wings, but otherwise it's not really any different from fuel in the fuselage. Space saving really.

The longer and narrow wings generally give better high-speed high-altitude performance whereas wider, shorter wings are better at low-speed low-altitude. Most wings you make will be a composite of different wing parts anyway though, so any particular quirks will probably be averaged out once it's all stuck together.

EDIT: In career mode you do unlock different wings at different stages of progression. In stock the largest parts tend to come at the end rather than the most developed, but early wings tend to be of the good-for-low-and-slow type and then progress to better-for-high-and-fast type, before getting into the super-size stuff.

Edited August 29, 2015 by The_Rocketeer

[jiminator]

Not an expert at this, but I suspect the more parts you use the more drag surfaces you are creating. So the fuel tank wings are big for the lift and you can skip some tanks, thus less drag surfaces and more work per pound vs separate tanks and multiple wing sections

[The_Rocketeer]

That used to be true in stock atmo, but I believe the new atmo model allows for the fact that parts behind other parts are shielded from most drag effects. It's not quite as straightforward as that - the leading edge creates a shock cone that reduces the affect of drag on any parts that are 'inside' it.

[BudgetHedgehog]

The longer and narrow wings generally give better high-speed high-altitude performance whereas wider, shorter wings are better at low-speed low-altitude. Most wings you make will be a composite of different wing parts anyway though, so any particular quirks will probably be averaged out once it's all stuck together.

Depends on orientation.

Far left (low aspect ratio) is good for supersonic speeds, far right (high aspect ratio) gives better performance at subsonic speeds and at gliding. Depends on the EAS though - at high altitudes (and lower density air), you'll need to be going faster to generate the same amount of lift compared to a lower altitude. The long and narrow wings give better high altitude performance but should be terrible at higher speeds and vice versa. That said, I remember reading that all wings change their lift profile automatically based on EAS - doesn't really matter what shape they are, at subsonic speeds, they're all high aspect ratio wings and at supersonic and beyond, they're low aspect ratio wings. Something like that, anyway. Could be wrong.

[jiminator]

The atmospheric model has quite a ways to go. someone did tests and found batteries hidden under a cone are worse because of the wide profile vs mounting to the side. The exception will be in containers.

[sardia]

The atmospheric model has quite a ways to go. someone did tests and found batteries hidden under a cone are worse because of the wide profile vs mounting to the side. The exception will be in containers.

That makes no sense, I thought KSP does model aero occlusion?

Anyway, is the aspect ratio thing right? I can just throw on a bunch of strakes, and it doesn't matter if its the bigS strake or the normal one? My goal is to get a SSTO mk3 cargo container into orbit. Then I can have all sorts of inefficient slow launches, but the cool factor is hard to say no to.

[BudgetHedgehog]

That makes no sense, I thought KSP does model aero occlusion?

Only for stack mounted parts. Radially attached parts, clipped inside or otherwise, are still subject to aero forces.

[The_Rocketeer]

Depends on orientation.

http://sciencelearn.org.nz/var/sciencelearn/storage/images/media/images/flt_sci_art_04_wing_aspect_ratio_lowtohighratios-nc2/529619-1-eng-NZ/FLT_SCI_ART_04_Wing_aspect_ratio_LowToHighRatios-NC.jpg

Far left (low aspect ratio) is good for supersonic speeds, far right (high aspect ratio) gives better performance at subsonic speeds and at gliding. Depends on the EAS though - at high altitudes (and lower density air), you'll need to be going faster to generate the same amount of lift compared to a lower altitude. The long and narrow wings give better high altitude performance but should be terrible at higher speeds and vice versa. That said, I remember reading that all wings change their lift profile automatically based on EAS - doesn't really matter what shape they are, at subsonic speeds, they're all high aspect ratio wings and at supersonic and beyond, they're low aspect ratio wings. Something like that, anyway. Could be wrong.

Yeh this is what I was saying but with moar technical terms.

[John FX]

Myself, I would really like the aero model in KSP to do some form of basic Ray casting where if you have a line of radially mounted parts the first one will at least partially occlude the ones behind it. While I can understand maybe this not being quite so cut and dried when dealing with air, it should definitely be the case when in space dealing with solar radiation.

Edited August 30, 2015 by John FX

[sardia]

Only for stack mounted parts. Radially attached parts, clipped inside or otherwise, are still subject to aero forces.

Does that mean it doesn't matter what wings I use? Because I tinker with the wings all the time(to get the center of mass right) and it performs different each time.

[GoSlash27]

sardia,

It does matter which wings you use. Different wings have different "drag cube" values, lift ratings, and mass densities.

Somebody posted the new drag values (not the same as the old config file numbers) but I don't recall where they were posted. I think they were also the edge- on "parasitic" values rather than the "induced" values that come with making lift.

Best,

-Slashy

[sardia]

sardia,

It does matter which wings you use. Different wings have different "drag cube" values, lift ratings, and mass densities.

Somebody posted the new drag values (not the same as the old config file numbers) but I don't recall where they were posted. I think they were also the edge- on "parasitic" values rather than the "induced" values that come with making lift.

Best,

-Slashy

Thanks, now I just need to find out which wings are the best/optimal for what I want.

Where does mechjeb show drag values? I didn't see it in any of the windows.

[GoSlash27]

sardia,

I wouldn't know anything about that, sorry.

I do have a list I've compiled from the data I mentioned:

Area Cd Part

0.0858 0.0723 AV-T1 Winglet

0.536 0.0963 Big-S Wing Strake

0.153 0.213 Wing Strake

0.0280 0.220 Basic Fin

0.884 0.295 Swept Wings

0.184 0.337 Structural Wing Type D

0.363 0.338 Structural Wing Type A

2.22 0.409 Big-S Delta Wing

0.735 0.441 Delta Wing

0.735 0.441 Swept Wing Type A

0.363 0.443 Small Delta Wing

0.753 0.484 Swept Wing Type B

0.735 0.492 Structural Wing Type B

0.191 0.506 Wing Connector Type D

0.753 0.507 Wing Connector Type B

0.735 0.509 Structural Wing Type C

4.75 0.512 FAT-455 Aeroplane Main Wing

0.367 0.515 Wing Connector Type A

0.367 0.515 Wing Connector Type C

0.367 0.515 Wing Connector Type E

This is strictly edge-on drag numbers. I don't have any source for the side-on values.

I crunched these numbers with the lift values and came up with a heirarchy of wings for lift/ drag.

Here they are in ascending order of load capacity and (mostly) descending order of efficiency:

1) AV-T1 winglet, 59.6. Estimated load capacity 3 tonnes per pair

2) Wing strake , 15.3. 4t

3) BigS strake, 19.4. 8t. Bonus: They carry 200 units of LF per pair.

4) Connector A 10.6. 16t.

5) SweptB, 6.2. 18t

6) BigS Delta, 5.5. 40t. Bonus: They carry 600 units of LF per pair.

7) Airliner wing, 3.2. 62t. Bonus: They carry 1,200 units of LF per pair.

[Nich]

That just doesn't seem right GoSlash. The AV-T1 winglests are 10x more efficient then the big S wings? I will have to try an exploit craft with 20 pairs of these

[GoSlash27]

Nich,

I can't guarantee that this is correct. That's just what the math suggests based on the info I have.

Please let us know if the AV-T1 makes a miracle- plane. Remember, nothing else can attach to those. You're limited by surface area.

Best,

-Slashy

*edit* Also remember that the drag performance of wings is much better than fuselage sections (especially the Mk2) and clean design matters more than either of those.

Edited August 31, 2015 by GoSlash27

[xtoro]

Wings with fuel in them make balancing easier. As you use fuel, your CoM changes. Using a tool like RCS Build Aid shows you your Dry CoM(DCoM). Place your fuel, or wings with fuel in them so that your CoM and DCoM are as close to each other as possible. If you find your CoL is still too far behind, use the rotation widget to angle your wings up a bit. This will bring your CoL forward. Don't forget to check that your engines are level if they're mounted on the angled wings by using the rotation widget on them too.

[Claw]

Hey guys, not to spoil the fun but I want to clear up some confusion about aero in KSP. I've actually outlined a lot of it at the link below (also stickied in this forum).

http://forum.kerbalspaceprogram.com/threads/119108-Overhauls-for-1-0

However, the TLDR version relevant here is that lifting surfaces and control surfaces do not use the drag cube values to calculate drag. Drag for aero surfaces is calculated off of their lift rating, and lift rating is calculated based on physical part dimension. There may be some slight variance in lift/area, but it will be minimal.

What that all means is that all the wing parts are equal in the sense that if you build a wing out of several parts that is the same size as a single wing part, you will have the same lift and drag rating.

It is also true that radially mounted parts are subject to the windstream, even if hidden in a nosecone. You'll have to hide those things in a service bay or cargo bay when possible. Wings are a special case of this though, because they don't use the cube values, but a scaled product of their lift.

Fuel in the wing does not affect their "wing" properties (lift or drag). Using them is better than adding extra side tanks, but is a matter of preference if you want to put the fuel in the fuselage or not. However, using them for fuel can reduced fuselage size, which also results in lower drag.

Cheers,

-Claw

Edited August 31, 2015 by Claw

[xtoro]

Good info Claw. And for the record, my post was about fuel balancing using fuel in the wings and not lift or drag. I was just pointing out an advantage to using them...

[Wolf Baginski]

If you're flying a plane with wings on the default alignment you'll see that the plane is pointing slightly above the prograde indicator in level flight, and a bigger wing will reduce the difference. That's basic aerodynamics. At any particular angle-of-attack, the bigger wing has more drag. But it needs a lower angle-of-attack to get the same lift. And if you're flying nose-high the fuselage will generate more drag.

So a slight rotation of the wings will pay off. How much? You would have to test, but least drag at cruising speed will have the nose and prograde markers aligned and on the horizon.

The classic short-wing high-speed design is the F-104 Starfighter. It was designed for altitude and speed, as was the English Electric Lightning used by the RAF, which solved the problems by a Kerbalish answer, "Moar thrust!". It still has fairly small wings.

I usually use Procedural Wings for my spaceplanes, and with the body lift from Mk2 parts it can sometimes be a bit tricky getting weight far enough forward. I have successfully flown a Mk2 design with no wings, but directional stability was low, and take-off speed was in the silly-high range.

A while back, I built a plane reminiscent of the bomber designs of the early Fifties, and flew non-stop around Kerbin at sub-sonic speeds. With more powerful engines and better intakes it would go supersonic. But the wing was big, probably too big.

[GoSlash27]

Hey guys, not to spoil the fun but I want to clear up some confusion about aero in KSP. I've actually outlined a lot of it at the link below (also stickied in this forum).

http://forum.kerbalspaceprogram.com/threads/119108-Overhauls-for-1-0

However, the TLDR version relevant here is that lifting surfaces and control surfaces do not use the drag cube values to calculate drag. Drag for aero surfaces is calculated off of their lift rating, and lift rating is calculated based on physical part dimension. There may be some slight variance in lift/area, but it will be minimal.

What that all means is that all the wing parts are equal in the sense that if you build a wing out of several parts that is the same size as a single wing part, you will have the same lift and drag rating.

It is also true that radially mounted parts are subject to the windstream, even if hidden in a nosecone. You'll have to hide those things in a service bay or cargo bay when possible. Wings are a special case of this though, because they don't use the cube values, but a scaled product of their lift.

Fuel in the wing does not affect their "wing" properties (lift or drag). Using them is better than adding extra side tanks, but is a matter of preference if you want to put the fuel in the fuselage or not. However, using them for fuel can reduced fuselage size, which also results in lower drag.

Cheers,

-Claw

Claw,

Excellent information! Do you happen to know the formulas by which these are derived? It'd be handy to be able to recreate these curves mathematically for engineering purposes.

Best,

-Slashy

[Claw]

Do you happen to know the formulas by which these are derived?

Depends on what you mean by "these." The curves for lift is split in two parts. One curve is essentially Coefficient of Lift (Cl) vs. AoA, and the other is a Cl vs. Mach curve. Those values are then used in the lift equation (multiplied by the lift rating) to come up with a lift force for that wing section.

The same method is used for determining drag, which also uses the lift rating to scale the final drag force. Drag has it's own Coefficient of Drag (Cd) vs. AoA and Cd vs. Mach curves.

All four of thse curves are Unity float curves, and are available in one of the .cfg files, although I forget the name off hand and can't look atm.

Hopefully that helps.

Cheers,

-Claw

[GoSlash27]

Claw,

I found it. It's in the physics.cfg file.

Thanks about a million! This is gonna be handy!

*edit* Wait... there's only a generic set of curves in there. Are these values all multiplied by the wing's lift rating to generate the final values?

Best,

-Slashy

Edited September 1, 2015 by GoSlash27

[sardia]

What about the earlier talk about wing aspect ratio? Does that mean it doesn't matter? Because I have a feeling that the fat wings aren't nearly as good as a bunch of S strake wings clipped together. Is it just my imagination or are there other differences that are more important?

[Nich]

Depends what they are using but nasa uses

CL = L / (A * .5 * r * V^2)

CL = cofficient of lift

L = Lift

A = Area but they may using lift cofficient here

r = reynolds number (bassed off speed, viscoscity and cord length)

V = Velocity relative to the ambient airflow

However what you really want is the CL/CD max. this is your optimal angle for climb. The larger the value the better the wing. I wanted to look into these files and make some graphs but I didnt have anytime last night.