KSP .90 Spaceplane wing comparo

[GoSlash27]

All,

I figured I'd post this here before the next update comes along.

This is a direct comparison of drag and mass for a fixed amount of lift for each wing surface type.

KSP .90 Wing type comparison

[TABLE=class: cms_table, width: 500]

[TR]

[TD]Type[/TD]

[TD]Cl[/TD]

[TD]Cd[/TD]

[TD]Mass[/TD]

[TD]N@Cl=10[/TD]

[TD]Mtotal[/TD]

[TD]Dtotal[/TD]

[/TR]

[TR]

[TD]Swept[/TD]

[TD]1.6[/TD]

[TD].6[/TD]

[TD].05[/TD]

[TD]6.25[/TD]

[TD].31[/TD]

[TD].0641[/TD]

[/TR]

[TR]

[TD]Conn A[/TD]

[TD]2[/TD]

[TD].5[/TD]

[TD].1[/TD]

[TD]5[/TD]

[TD].5[/TD]

[TD].0855[/TD]

[/TR]

[TR]

[TD]Conn B[/TD]

[TD]2[/TD]

[TD].5[/TD]

[TD].1[/TD]

[TD]5[/TD]

[TD].5[/TD]

[TD].0855[/TD]

[/TR]

[TR]

[TD]Conn C[/TD]

[TD]1[/TD]

[TD].25[/TD]

[TD].05[/TD]

[TD]10[/TD]

[TD].5[/TD]

[TD].0428[/TD]

[/TR]

[TR]

[TD]Conn D[/TD]

[TD].5[/TD]

[TD].12[/TD]

[TD].025[/TD]

[TD]20[/TD]

[TD].5[/TD]

[TD].0205

[/TD]

[/TR]

[TR]

[TD]Conn E[/TD]

[TD].5[/TD]

[TD].12[/TD]

[TD].025[/TD]

[TD]20[/TD]

[TD].5[/TD]

[TD].0205[/TD]

[/TR]

[TR]

[TD]Delta[/TD]

[TD]2[/TD]

[TD].6[/TD]

[TD].1[/TD]

[TD]5[/TD]

[TD].5[/TD]

[TD].1026[/TD]

[/TR]

[TR]

[TD]Sml Delta[/TD]

[TD].5[/TD]

[TD].1[/TD]

[TD].025[/TD]

[TD]20[/TD]

[TD].5[/TD]

[TD].0171

[/TD]

[/TR]

[TR]

[TD]Strake[/TD]

[TD].75[/TD]

[TD].2[/TD]

[TD].025[/TD]

[TD]13.3[/TD]

[TD].33[/TD]

[TD].0228[/TD]

[/TR]

[TR]

[TD]Struct A[/TD]

[TD]1[/TD]

[TD].3[/TD]

[TD].05[/TD]

[TD]10[/TD]

[TD].5[/TD]

[TD].0513[/TD]

[/TR]

[TR]

[TD]Struct B[/TD]

[TD]1[/TD]

[TD].3[/TD]

[TD].05[/TD]

[TD]10[/TD]

[TD].5[/TD]

[TD].0513[/TD]

[/TR]

[TR]

[TD]Struct C[/TD]

[TD].5[/TD]

[TD].15[/TD]

[TD].025[/TD]

[TD]20[/TD]

[TD].5[/TD]

[TD].0257[/TD]

[/TR]

[TR]

[TD]Struct D[/TD]

[TD].25[/TD]

[TD].08[/TD]

[TD].012[/TD]

[TD]40[/TD]

[TD].48[/TD]

[TD].0131[/TD]

[/TR]

[TR]

[TD]Swept A[/TD]

[TD]1[/TD]

[TD].3[/TD]

[TD].05[/TD]

[TD]10[/TD]

[TD].5[/TD]

[TD].0513[/TD]

[/TR]

[TR]

[TD]Swept B[/TD]

[TD]1[/TD]

[TD].3[/TD]

[TD].05[/TD]

[TD]10[/TD]

[TD].5[/TD]

[TD].0513

[/TD]

[/TR]

[/TABLE]

So what I've done here is assumed the normal rule of thumb: 10x lift coefficient for each 10 tonnes of spaceplane. I've used enough of each wing type to achieve that goal.

Then I assumed that they were in their most efficient angle of attack and looked at how much mass and drag they represented.

The drag numbers are dimensionsless, and therefore do not take into account velocity or air pressure, but they are directly comparable to each other in any given circumstance.

Now... for a 10 tonne spaceplane, a difference of a couple hundred kg doesn't matter much. But the drag is very important.

As we climb over the 25-32km "hump", our engine thrust begins to reduce, and we are looking at our thrust to drag to keep us accelerating. Our 10 tonne spaceplane will generate 2 dimensionless "units" of drag in this regime, so it's vital that we don't add more drag than we have to.

After that, it's just a matter of t/w to get us to orbit and circularized.

I recommend that you use low drag and low mass wings whenever you can. I also recommend that you use the *proper amount* of wings whenever you can.

Best,

-Slashy

Edited December 28, 2014 by GoSlash27

[Frank_G]

This is pretty useful! Thanks