Fuselage Effect of VSPAero VLM

[Cheol-Kyun Choi]

Hello. Rob

I have heard many times that VLM of VSPAero cannot calculate force of fuselage component.

and it is true.

It cannot make any lift only with fuselage

but, during some test, fuselage looks like affect on the force coefficient

let's see below

that is the result of wing analysis

and

that is the result of simple body - wing analysis

and

that is the result of complex body - wing analysis

each cl result are like that

Only wing                   : 0.10666

Simple body + wing   : 0.10104

Complex body + wing: 0.13346

Because of this, fuselage looks like generate lift

I wonder if it is what you intended....

I attached my result

Thank you!

Have a good weekend~

[Rob McDonald]

The presence of a fuselage can certainly change the flow on the wing -- which will change the force on the wing.

The fuselage does not have its own wake.  If you were to look at the forces on just the fuselage (I'm not sure if we output that) you would see that they are zero.

Rob

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[Cheol-Kyun Choi]

Thank you Rob

When I run the VSPAero with fuselage only,
It doesn’t make force(In fact, very small to ignore)
What I want to talk is, sometimes fuselage affect on the force(wing wake)
Sometimes it is big

So then the problem is,
“Make the fuselage well”
Is that right?

[Brandon Litherland]

In your third example, you'll notice that the leading edge of the wing is very close to, if not intersecting, the fuselage cruciform.
This can cause significant issues with the panels/lattice in that region.  In each case,  pay close attention to the legend.  You will notice that the peak values (positive and negative) can be very different with this type of interference, sometimes showing peak delta-Cp values over +/-400.

I suspect that these peaks at the leading edge are causing the large jump in CL.  If you also look at the lift distribution in the results manager, you should see strong peak regions when local cells are affected.

[Cheol-Kyun Choi]

Thank you!

I will try more case with your advise

From CK