F-35 vs F-16

[OutOnTheOP]

The important difference here though is that the F-16's intake is situated below the lifting body/fuselage, same as on the Su27 & F-14, and there's a spacing with a horizontal wedge between the intake and the fuselage for the first meter or so as well.

 

Thus the F-16 gains the benefit of the air impacting a sharp leading edge across the span of the aircraft's front profile, where'as on the F-35 there's two larges areas of the front profile where the air instead first comes into contact with a large air intake. The effect of this will be the same as that of placing an air intake on the leading edge of an airfoil/wing, which will results in a decrease in CLmax and increase in drag - thus decreasing the in L/D ratio. Said thing was demonstrated on aircraft such as the the F4U Corsair & Hawker Fury, where the parts of the wing featuring the leading edge radiator intakes suffered a marked decrease in CLmax and an increase in drag.

 

Yeah, except there's a huge difference between air flowing through a radiator, where it is progressing in a turbulent manner through a barrier, quite possibly coming out slower than it went in, versus going through an ENGINE that is ejecting it at higher speed than it went in.

 

It's really hard to take seriously the critiques of someone who bases their arguments around assessments of drag and fuselage lift from eyeballing a picture. Because, y'know, the engineers that designed it, using massive computing power to assist in optimization, had no clue how to ensure high body lift.

[Exorcet]

The important difference here though is that the F-16's intake is situated below the lifting body/fuselage, same as on the Su27 & F-14, and there's a spacing with a horizontal wedge between the intake and the fuselage for the first meter or so as well.

In stark contrast to the Su-27/F-14 though, the intake doesn't act like a giant fence to prevent air from spilling over the edge and building up pressure in a central tunnel. Also, the gap between the intake and the fuselage could lead to separation and reduced pressure on the LERX, similar to rounded edges on the bottom of the F-35 inlets (though like the wings on the F-35, the LERX pressure may help here).

 

Thus the F-16 gains the benefit of the air impacting a sharp leading edge across the span of the aircraft's front profile, where'as on the F-35 there's two larges areas of the front profile where the air instead first comes into contact with a large air intake. The effect of this will be the same as that of placing an air intake on the leading edge of an airfoil/wing, which will results in a decrease in CLmax and increase in drag - thus decreasing the in L/D ratio. Said thing was demonstrated on aircraft such as the the F4U Corsair & Hawker Fury, where the parts of the wing featuring the leading edge radiator intakes suffered a marked decrease in CLmax and an increase in drag.

The Corsair and Fury are quite a bit removed from the modern fighter layout, and the radiators won't be sucking air in, but rather slowing it down with high pressure. They also lacked vortex generating structures around those intakes. No doubt there will be a lot of air directed toward the F-35's inlets, but there will also be air going around the inlet and directly hitting the small LERX ahead of the wing. Even if the inlets are taking a hit in lift, the upper surface pressure on the F-35 is probably very similar to the F-16 along the leading edges. In addition it has a wider fuselage and most likely a higher underbody pressure at the same AoA.

[Hummingbird]

Yeah, except there's a huge difference between air flowing through a radiator, where it is progressing in a turbulent manner through a barrier, quite possibly coming out slower than it went in, versus going through an ENGINE that is ejecting it at higher speed than it went in.

 

This will primarily have an influence on drag, but not really the loss in lift.

 

It's really hard to take seriously the critiques of someone who bases their arguments around assessments of drag and fuselage lift from eyeballing a picture. Because, y'know, the engineers that designed it, using massive computing power to assist in optimization, had no clue how to ensure high body lift.

 

All designs feature compromises in order to reach a certain primary goal, and the same is true for the F-35. It isn't about engineers not knowing how to make a high lift body, they could make the perfect one if they wanted to, but not without making sacrifices in other areas, which is the point you're missing here.

 

Keep in mind that the F-35 was never intended to be an air superiority fighter able to outmaneuver everything else in the sky, thus the design was never going to be centered around achieving the highest possible amount of maneuverability or performance. Instead the F-35 was primarily designed to be a stealthy strike fighter, able to sneak into areas unseen and take out the air defenses there before they ever know what is happening.

[Hummingbird]

In stark contrast to the Su-27/F-14 though, the intake doesn't act like a giant fence to prevent air from spilling over the edge and building up pressure in a central tunnel. Also, the gap between the intake and the fuselage could lead to separation and reduced pressure on the LERX, similar to rounded edges on the bottom of the F-35 inlets (though like the wings on the F-35, the LERX pressure may help here).

 

The F-16 does not feature the tunnel as on the true lifting body designs of the Su27 & F-14, I agree and that's why I've always drawn a distinction between them. However the similarity is the placement of the intake under the lifting surface (in contrast to the F-35 where it's on the leading edge of the lifting surface, which is a crucial difference) making sure that the air is first met by a carefully shaped leading edge across the span of the aircraft. This is where I'd say the F-16 has an advantage in terms of lift production and overall L/D ratio, just the same as it has it over the F-15 which also features its intakes on the leading edge of its fuselage, and it's no doubt also part of the reason that the F-16 outperforms the F-15 in maneuverability despite a noticable difference in wing loading and generall advantage in T/W ratio in favour of the Eagle. The F-16 simply has to be more efficient at generating lift than the F-15 for this to at all be possible.

 

 

The Corsair and Fury are quite a bit removed from the modern fighter layout, and the radiators won't be sucking air in, but rather slowing it down with high pressure. They also lacked vortex generating structures around those intakes. No doubt there will be a lot of air directed toward the F-35's inlets, but there will also be air going around the inlet and directly hitting the small LERX ahead of the wing. Even if the inlets are taking a hit in lift, the upper surface pressure on the F-35 is probably very similar to the F-16 along the leading edges. In addition it has a wider fuselage and most likely a higher underbody pressure at the same AoA.

 

Of course there is a difference, agreed, but primarily in the percentage wise magnitude of the lift lost and drag incurred, the main point being that you don't go unpunished by having two gaping holes on the leading edge of a lifting surface :)

Edited May 18, 2015 by Hummingbird