# How can I derive lift coefficients of wing area and horizontal stabilizers seperately from available data?

I am fairly new to aerodynamics and I am trying to create a flight simulation based on data available for F-4E Phantom.

I found various flight test data for this particular aircraft and trying to create lift coefficient slope vs AoA. So, as far as I know, I can calculate the lift force from this for the whole aircraft. This will be sum of wing, elevator, fuselage and engine lift. Can I use wing area as reference to calculate lift coefficient? Can I use this coefficient to find tail lift force? There isn't any AoA indicator in these data, so I can't really draw the slope from this. Any direction to what can I do or what SHOULD I do will be much appreciated.

There are 2 ways to try. If you know where the CG is, lift coefficient of the horizontal stabilizer can be derived from the torque downforce required to maintain pitch attitude against the wing torque (around the center of gravity).

Or, you could find the airfoil type and look at the polars.

Coefficient of lift is really a combination of airfoil type and Angle of Attack. I don't know why these are kept together, instead of being separate variables in the Lift Equation, but this is what Coefficient of lift is.

That amount to downforce (or upforce) the tail must provide is dependent on CG location. For a F4E Phantom simulation, CG location is therefor critical, along with considerations of inertia of the jet.

The F4 has plenty of power, but is also very heavy.

• That amount to downforce (or upforce) the tail must provide is dependent on CG location, yes, and on flap settings and slat position. Also, the shift in the center of pressure over Mach should significantly influence the results. Airfoil data is less of a concern, given that the F-4 is optimized for supersonic flight. That makes the airfoil awfully close to a flat plate. Apr 27, 2022 at 19:19

The table in the question is data in the drag axis: how much fuel is used at which speed. It looks to me like the Drag Index is a measure for external weapons configuration, if that is the case then the data at Drag Index 0 would yield the thrust required for pertaining the relevant cruise speed - if only we knew the thrust efficiency of the F-4E.

The Lift Coefficient is part of the lift equation, and lift in cruise is equal to weight. And there is nothing in the table of much relevance to lift computation.

Can I use wing area as reference to calculate lift coefficient?

Yes, all lift and drag computations use the projected wing area as a reference for lift and drag equations.

Can I use this coefficient to find tail lift force?

Finding the lift coefficient $$C_L$$ of the whole aircraft, and finding the lift coefficients of wing and tail separately, are 2 different things. First thing indeed could be computing aircraft $$C_L = 2W / (\rho V^2 S)$$. S is the wing area, which can be looked up in wiki, and $$\rho$$ and V follow from the data in the table.

No there is no Angle of Attack data in the above equation, for that the airfoil data $$c_l$$ (lower case!) is required. Plus indeed data on CoG location, moment arms, tail airfoil data etc. And sadly none of that can be derived from the table in the question.