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Fuselage lift questions


Madscientist16180
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Hello people.

I was trying to build a pretty weird craft, and came upon a behavior i was not expecting concerning the MK2 serie of fuselage parts.

So, here is a first shot:

0SLkLyc.png

I would expect this (line of mk2 fuselage rotated on their side) to show some lift on one side, probably to the right of the image given how i rotated the parts.

But as the indicators show, there is no lift produced.

Then, i rotated each fuselage to get a ring, and it was now producing lift...

Shot:

QjxTrfR.png

Close-up shot:

SDdafoG.png

It might be useful to know that on this shot, the root part is a mk2 cargo bay and it's the part on the right, 90 degree from the lift vector.

I was expecting this to be neutral as far as lift is concerned, seeing that i have equal lift all around, and that i was careful rotating them so the face in the same way. Am i wrong in my assumption that this should show no lift?

 

But then, it does other strange thing,

Shot:

1XO3czq.png

Here, i just rotated the whole ring, going by the previous shot, lift should point down, but It now point to the side, at the root part.So, if i place it "lying down" like the first shots, and then upright, i get different lift vector. Could well be me missing something obvious, but i do not get it.

So i decided to try and place back my lift vector where i wanted it with wings inside the ring, got there:

Shot:

faKXRjm.png

Lift looks pretty straight up. with a backward angle.

 

Fact is, the craft does not fly like the vector is there at all, as soon as it get a bit of speed, it push hard toward the direction opposite the root part, like the lift is now offset to a side it never show in the editor.

So, am i wrong in assuming that the ring should produce neutral lift vector? And from there, if i'm wrong, what is it i do not get that shift my vector?

 

Side note: The craft attitude is controlled with reaction wheels that i clipped in the fuselage, 12 of them. And i placed RCS thrusters evenly over the fuselage in the hope of getting enough attitude control to offset the problems, did not worked.Then i attached elevon on the backside, they helped a bit.

I get it that this will be a really really draggy thing and that it maybe should not really fly, but it is so close too doing it i'm sure i can get there with a bit of help. I'm good at rocket, very inexperienced at "planes".

 

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Wings in KSP do not have a "top" or "bottom."  They will generate lift as long as you have some angle of attack.  So with a craft like that, lift will vary greatly depending on which direction it's pointing.  

Not really following what happens when you fly it.  Are you launching vertically (from the launchpad) or horizontally (from the runway)?

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10 hours ago, Aegolius13 said:

Wings in KSP do not have a "top" or "bottom."  They will generate lift as long as you have some angle of attack.  So with a craft like that, lift will vary greatly depending on which direction it's pointing.  

Not really following what happens when you fly it.  Are you launching vertically (from the launchpad) or horizontally (from the runway)?

I launch it vertically, from the runway lol. But now i get it, been testing all night. I think the fuselage ring ends up generating rotation. Somewhat like if the fuselage where facing the airflow.

 

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In the VAB, lift is calculated as if wind were coming down from above, and very slightly (less than a degree) from the East.

In the SPH, it's from what by default is forwards, and very slightly from below.

Where you root part is doesn't matter for that.

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