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Basic Aircraft Design - Explained Simply, With Pictures

keptin

By keptin
in KSP1 Tutorials

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B787_300

B787_300

Posted
Posted
Thanks for the infographic, I'll probably end up referring to it at some point when I take stability & control of aircraft next Fall semester :^) A much easier read than my Aerodynamics textbook.

I know what you mean my friend, if only all text books took the ELI5 approach and had tons of pictures

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keptin

keptin

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Posted (edited)
I just ran across this.

This isn't stickied? Why isn't this stickied?!

Huh, it used to be stickied. Squad giveth and Squad taketh away.

Now that we have tweakables in 0.23 I'm tempted to update it soon and add a section on empennage/control-suface layout.

TailTypes.gif

Mmm...empennage.

And...

-Mounting engines tilted to account for asymmetric thrust.

-Laminar flow

-Canard configuration

-Editing dated graphics

Edited by keptin
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Claw

Claw

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Keptin,

Heya. I am in the middle of writing a tutorial and was wondering if I could mention your thread. I thought your information was really well laid out. So I'm structuring my tutorial to mostly follow your article if that's cool with you.

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B787_300

B787_300

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not sure if srs...

very serious, while i like the cartoon this diagram also relates quite well to IRL plane design and I have showed it to one of my COLLEGE teachers and he wants to make a version that is less cartoony and has no reference to KSP

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I_Killed_Jeb

I_Killed_Jeb

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very serious, while i like the cartoon this diagram also relates quite well to IRL plane design and I have showed it to one of my COLLEGE teachers and he wants to make a version that is less cartoony and has no reference to KSP

then good for your COLLEGE teacher?

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keptin

keptin

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Keptin, if you were to update would you redo the graphics to be less cartoony?...while i like the cartoon this diagram also relates quite well to IRL plane design and I have showed it to one of my COLLEGE teachers and he wants to make a version that is less cartoony and has no reference to KSP

I like that "college" is in all caps. That's some serious s*%t.

All kidding aside, the original goal of the guide was to be more digestible and accessible than a textbook. I could have just included textbook images, which I'm sure your professors have access to, but then it'd be all lame sauce and uncool.

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Claw

Claw

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Huh, it used to be stickied. Squad giveth and Squad taketh away.

Now that we have tweakables in 0.23 I'm tempted to update it soon and add a section on empennage/control-suface layout.

Mmm...empennage.

And...

-Mounting engines tilted to account for asymmetric thrust.

-Laminar flow

-Canard configuration

-Editing dated graphics

If you're considering an update for empennage/control-surface layout, canards, etc... I would be interested. Here is a picture of the aircraft I'm toying with for a new tutorial. Right now it's about control surfaces and moments of inertia. I was thinking about adding a T-tail but I'm not sure I want to complicate this design with one. Perhaps that would be best done with another aircraft.

An3vsAs.jpgMXhUbeE.jpg

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numerobis

numerobis

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Fantastic overview!

Your explanation of how wings work is not quite how they work in KSP.

First off, there's two wing types: "ModuleControlSurface" and "Winglet", the latter being a confusing name. If it moves, it's a control surface, and that includes the AV-R8 winglet. If it doesn't move, it's a "Winglet", and that includes the swept wing and so on -- because of the confusion, I call them control surfaces and wings, respectively.

The wing gives lift that varies with 

cos(AoA + 90) (1 - abs(cos(AoA + 90))) cos(AoA)

Then you multiply this by the lift value of the wing, the air speed, and the air pressure to get a force in kN. The direction is perpendicular to the velocity.

That wing lift function increases until about 25.7 degrees. Then it slowly goes to zero as we approach 90 degrees. You never get a hard stall, you just slowly lose lift.

The control surface gives lift that varies with cos(AoA + 90). So it goes up and up until 90 degrees. At 90, I believe it continues (and thus begins to fall), but I'm less certain of that conclusion since a bunch of signs flip. I'll have to experiment -- so far I've cared mostly about low angle of attack behaviour.

Conclusion: contrary to real life, the canard loses lift after the wing. And you don't stall like real planes do.

uYueC9S.png

Edited by numerobis
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keptin

keptin

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@numerobis, wow, I never realized that! Huh, yeah, then you're right about canards not stalling before the wing. Bummer. I wonder how FAR compares; I should do a comparison with the same aircraft at some point. I'm a bit torn between changing the guide or not to reflect this new info since it would be teaching the contrary, but maybe I can mention it in a future update. After all, I don't want to teach the wrong thing and the guide's higher purpose is to teach people about aircraft, not necessarily aircraft in KSP.

Thanks numerobis for pointing that out!

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DeliciousPi

DeliciousPi

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Posted

Hey, Keptin. First of all, thanks for the great tutorial. However... I'm doing a science project on the aerodynamics of paper planes with a buddy of mine. This thread first inspired us to come up with that idea. However, that's besides the point. We're doing our board right now, and were wondering: may we please print out the section of the guide where you explain the CoL with pictures and show it on our board? Just the part with the different wings with no fuelage and the blue CoL dot in the center. We will not modify it in any way, nor claim that it is ours or that we made it. You will be given full credit in the bilbliography. It's just... a really great visual explanation for the other students who will come by to look, far better than anything else we could find online... or draw. :P

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DeliciousPi

DeliciousPi

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Posted

Keptin... Thank you so, so much. I just figured that since I "knew" who made it, I should probably ask permission. It's just that most other explanations were unclear. Explaining it in words would have taken too long, due to the 2 1/2 minute time limit for the presentation. The fair's tomorrow, I'll let you know how it went. Unfortunately, the school has a blanket ban on pictures... If they catch you, it's grounds for suspension/expulsion. However, if I ever get to take it home perhaps I could take some pictures to show. In any case, If you want the info or report, just ask and I can upload them. Again, thank you!

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