# How to calculate lift for delta wing

1. May 9, 2007

### perrabananskruv

is the formula below valid to calculate the lift coefficient for a delta wing?

Cl=2*L/(rho*v^2*A)

L=lift (N)
rho= air density
v= air velocity
A=wing area

im doing a subsonic wind tunnel project where im going to measure the lift for a low aspect ratio delta wing. should i use another theory to calculate the lift?

2. May 10, 2007

### perrabananskruv

nobody knows?

3. May 10, 2007

### LovePhysics

I've never calculated lift on a delta wing, but why would the lift formula be any different? Approach it in a way you would any wing, with the proper values of course.

4. May 10, 2007

### Staff: Mentor

Yes, that looks valid to me. Going backwards from lift to lift coefficient via wind tunnel testing is the easiest and most accurate approach for lift analysis.

5. Jun 18, 2007

### luzirahs

yups...that's the exact method and correct way to measure lift.
can be use for any wing shape or any object.

just reverse the formula....u get the Lift from balance, u know the air density, air speed and also the wing area.

tadaaa...u'll get the Lift Coefficient, Cl in no time.

6. Jun 20, 2007

### Cyrus

Lets be clear, thats not a theory, thats a definition of the coefficient of lift, where the area A is probably going to be your planform area of the delta.

7. Jun 20, 2007

Maybe Vortex lift at high Angle of Attack. It only allows the delta to produce lift at higher angles of attack, but I'm not sure how it's going to be different from any wing producing lift prior to stall.

8. Jun 21, 2007

### FredGarvin

Since you are doing actual test work, you would need to couple the theoretical calculations with pressure distribution measurements around the entire planform area of the wing. That combined with the actual load measurements from the tunnel are the best way to characterize the lift of an entire wing.

9. Jun 8, 2008

### phoenixfire

surely there is a slight problem with the formula because 'A' (for a normal aerofoil anyway) is the cross sectional (average cross sectional in tapering) area of the wing. and deltas dont really have a standardable cross seectionabe area due to their shape

10. Jun 9, 2008

### caslav.ilic

Area can be anything. I could take it as that of pilot's boot sole -- if it would do me any good.

The full model geometry, test conditions, and measured forces are the hard data, and the referent area for coefficients is chosen according to the need. E.g. if comparing coefficients with other experiments, take the definition of area they used; if using coefficients in design calculations, take the definition of area agreed upon by the design team.

--
Chusslove Illich (Часлав Илић)

11. Sep 12, 2008

### Trevor Heley

I wonder if any of the posters on this thread can help?
I have just started radio controlled modelling. In the winter I am proposing to scratch build a Mirage 2000 delta wing plane using a Electric ducted fan. I am busy trying to get the manufactures details so I can start evaluation based on scale. The finished model will have a wingspan between 24 -30". Final size will be dependent on EDF sizes and powers available together with estimated model size, weight, lift, drag, etc.
Of couse my model will not fly supersonic and I assume I will have to modify the manufactures aerofoil shape to get better model performance.
I would appreciate any ideas on how I could proceed.
regards Trevor