Actual drag is 0.5xpx(velocity^2)xCdxSectionalArea. 0.5, p and SectionalArea are going to be constants.

I have a F-35 and F-16 desk model from the LM gift shop.

I took them both outside.

I was able to throw the F-35 model further.

... It's hard to say without knowing the precise details of its aerodynamic coefficients (namely CL vs. AoA and CL vs. CD... or CD vs. AoA if you prefer) and installed thrust figures just how well the F-35 will perform in terms of instantaneous turn rate, sustained turn rate, and minimum sustained turn radius.

And as far as a full data set, I'm sure it only comes from CFD models at this point in time seeing as how Lockheed Martin hasn't come close to completing the flight tests for the F-35A, let alone the B and C models.

Dwight , you still don't have it right about airplane coefficients. Section Area is not used as reference area. Wing area is the reference area for all airplane coefficients.

Exactly why I cringe when people start making performance assumptions based on some Cdo plot (and yes, it is Cdo, not Cdmin). It is only a small part of a much more complex picture.


One point, CFD has seen very limited (one might say insignificant) use in the buildup of the aero data model used for stability and control and performance predictions for the F-35 (and the F-22 and F-16 before that). It still comes back to a whole lotta hours in the wind tunnel.

You need to drop them off the roof of a somewhat tall building. The one that hits the ground first wins.

And it doesn't change the fact that total drag changes linearly with the Cd changes and increases exponentially with velocity changes. (Velocity is squared, Cd is not).

Of course what you are ignoring is that only part of total Cd is Cdo. A significant portion is Cdi, or drag induced from lift (CL). The velocity squared function applies equally to the lift term, so as you increase speed (at constant 'g') you also need exponentially less CL to get the same total lift (same weight, same g), so your Cdi is reduced accordingly. So, if you are increasing speed in an area where Cdo is flat, you wind up with a lower total Cd (again, assuming constant 'g'). Ultimately, the Cd vs CL slope will determine what happens to the total drag force as speed changes.

You're right. My expectations are extremely high considering I'm going to be one of the pink bodies in the jet when we go to war. The Viper is a lethal machine by any account. Therefore, any replacement should be a quantum leap beyond where the rubber meets the road.

The most important aspects to a fighter pilot are how well does it turn, how much does it carry, how far can it go and how fast can I go faster.

Sensor integration is also important but to a lesser degree.

With all the money they are spending on the Lightning II they should be able to make it lighter than the Viper.

Right now, the F-16 owns almost exclusively the vertical fight. Then next jet should be able to beat it. As it stands, the Lightning II doesn't have a 1:1.

So, comparing the F-22 point by point with the F-35. Would you care to speculate..............for argument sake?

I am estimating the weight of the F-35A at ~12.7 tons

under the assumption that some of the savings from the resign will transfer to the "A" variant even if it won't lose ~1.2 tons like the "B". 400 kg is a reasonable expectation.

...........and what is the range for both @ 50% fuel. Still not a far comparison......if you get my meaning?

It's incredible how people sometimes fail to understand that they just don't know.

One point, CFD has seen very limited (one might say insignificant) use in the buildup of the aero data model used for stability and control and performance predictions for the F-35 (and the F-22 and F-16 before that). It still comes back to a whole lotta hours in the wind tunnel.

johnwill wrote:
Quote:
Actual drag is 0.5xpx(velocity^2)xCdxSectionalArea. 0.5, p and SectionalArea are going to be constants.


Dwight , you still don't have it right about airplane coefficients. Section Area is not used as reference area. Wing area is the reference area for all airplane coefficients.


dwightlooi wrote:
We are talking about the total drag of an aircraft as it goes forward in flight. The wing area is an unrealistic representation of the top down area of the wing surface which has very little to do with drag. It makes ZERO sense to use wing area to compute total drag. A finless missile for instance will have ZERO wing area, but it will have a drag co-efficient and a finite drag component.

In anycase, regardless of the reference area you choose or believe is chosen, it is a constant. And it doesn't change the fact that total drag changes linearly with the Cd changes and increases exponentially with velocity changes. (Velocity is squared, Cd is not).

The subsonic Cd is shown as 0.02 for the clean F-16. I

Sink both of them in water,witch one comes up faster ?( Nose up )

Well, except there is a the fact that while drag as a function of Cdo and Cdi both increase exponentially with speed, Cdi is a function of the square of the L/D ratio which is typically around 10:1~15:1 for jet fighters. In otherwords only about 1 unit of drag is induced for every 10~15 units of lift produced. Hence, the drag "savings" from reduced lift generation is an order of magnitude less than the actually lift production reductions.

I mean one goes up as a function of V^2, the other goes down by a function of V^2 divided by 10~15.