F-14 vs F-15 vs F-16

[parsifal]

I'm not sure where he was going, either, but he did mention those two radar systems by name, so that was my starting point.

Yes, the AWG-9 was probably superior to the first-generation AN/APG-63 the F-15A had; it cetainly had superior range (at least double that of the -63), but I don't know if it had better look-down/shoot-down capability (for which the -63 was designed).

The later AN/APG-63(V)3 AESA radar, as fitted to late-model F-15C MSIP's, actually has many parts in common with the AN/APG-73 and AN/APG-79, as fitted to the F-18C and F-18E/F/G, respectively.

I would make the folowing modification to my comments in the light of your reply....because the two aircraft have different roles, they have different radar capabilities. What you are saying about "look down, shoot down capability does hold true when analysing the F-14 capability. They were not good at engaging from a superior height. Tomcats preferred to shoot from below, to avoid sea clutter effects on their radars. Shooting "down" had a significant downgrading effect on the efficiency of the system

I found this general link about the F-15, which people might find interesting

F-15 Eagle - Military Aircraft

A similar critique on the F-14 A/D can be found here:
AirToAirCombat.Com: Grumman F-14D Tomcat in Detail

 

[kool kitty89]

A good point was brought up, through all this debating the F-14 vas F-15's advantages, the F-16 has been almost forgotten.

It should be more agile than the other 2 (relaxed stability), except maybe at low speeds where the F-14's higher lift/drag comes in. The thrust/weight is somewhere between the F-15C and F-14D. (closer to the F-15) Wingloading is significantly higher than the F-15, but this alone doesn't say a whole lot. (the F-16's wing is thinner on average too, but the different planform and AR -and the F-16's root extentions- leave the question open)

The lower cost and maintenence of the F-16 has already been established.

How do the avionics and armament capabilities compare? (to both the F-14 and F-15)

 

[krieghund]

To SoD Stitch: Yes at long BVR the F-14/Aim-54 spalshed the F-15s. Remember the phoenix climbs to high altitude for a long range shot so it has manuver energy once the motor burns out, and the target my not have observed the launch (if he could see that far) so the missile would be falling from above using its strapdown inertial guidance until it went active. Once the F-14s were at medium range the F-15s closed the gap for lunch even though the F-14 had a better Instantaneous turn rate but the F-15 retains energy a bit better and It's all over.
I can't reveal the F-16 pod types but it does exactly that and really screws with european radars as well.
Yes the F-16 will win in a knife fight cause it bleeds off exactly half the energy that the F-15 does for the same g load, so just like the Yak3 vs the fw190 you pull it up for a wing over and defeat the target.
The delta wings are also at a disadvantage, if they pull hard they have just pissed away alot of energy. I have a chart of the Mir2000 vs F16Bk50 and the mirage just doesn't have the thrust to recover...the Typhoon does have more excess thrust but the g loss + the thrust makes it bleed like the F-16.
anyway its purely academic since the f-14 is retired and some moron had them scrapped. Each aircraft was made for a specific time and purpose and they did it well. But most important, its not how big the dog is in the fight, but how big the fight is in the dog!!!

 

[Soren]

Once the F-14s were at medium range the F-15s closed the gap for lunch even though the F-14 had a better Instantaneous turn rate but the F-15 retains energy a bit better and It's all over.

Well that confirms what I've been told and what I've said, the F-14 IS better than the F-15 in the horizontal, but the F-15 is better in the vertical. According to my friend F-14 pilots were taught to make a hard breaking turn in the horizontal if up against a/c such as the Tiger which the trainers sometimes fly in.

But that put aside the F-14 is better IMO purely because of its radar and armament.

In a scissors fight the F-16 beats them both it seems.

 

[Soren]

See above. And comment why a B-17 with lower wing loading and same span as a U-2 has a less efficient wing according to your 'theory' of span diameter tubes.

The B-17's wing produces less lift more drag pr. area than the U-2's wing, first of all because of it's lower AR, making it a less efficient wing than the U-2's. Furthermore the engine placement on the B-17's wing disturbs the span wise lift distribution over it and creates additional drag, both induced and parasite drag, making it even more inefficient.

 

[FLYBOYJ]

Well that confirms what I've been told and what I've said, the F-14 IS better than the F-15 in the horizontal, but the F-15 is better in the vertical. According to my friend F-14 pilots were taught to make a hard breaking turn in the horizontal if up against a/c such as the Tiger which the trainers sometimes fly in.

But that put aside the F-14 is better IMO purely because of its radar and armament.

In a scissors fight the F-16 beats them both it seems.

Once inside the merge, what did he say about the final outcome?

The F-14s opened at BVR range and ACMI indicated quite a few splashes, once they closed to med to short range they were decimated by the F-15. (No brag just fact)

Agree on the -16. When you mention Tiger, are you talking about the F-5?

 

[SoD Stitch]

To SoD Stitch: Yes at long BVR the F-14/Aim-54 spalshed the F-15s. Remember the phoenix climbs to high altitude for a long range shot so it has manuver energy once the motor burns out, and the target my not have observed the launch (if he could see that far) so the missile would be falling from above using its strapdown inertial guidance until it went active. Once the F-14s were at medium range the F-15s closed the gap for lunch even though the F-14 had a better Instantaneous turn rate but the F-15 retains energy a bit better and It's all over.

I knew the flight profile on the AIM-54 was parabolic; immediately after launch, the missle climbs until it's motor burns out, then coasts into the target. I believe the AIM-120C has a similar flight profile for long-range intercepts (but not short-range ones).

 

[The Basket]

The RAF would have chosen the Tomcat if they could have had it.

But got the Tornado F3 todo the same job. Sigh.

 

[renrich]

Krieghund, are the F14s in your example F14As or F14Ds with the GE engines? I have rather an extensive and comprehensive reference on the F14A with some information about the GE engines and the "Super Tomcat." Here are some interesting data: In level flight the automatic wing sweep causes the sweep to go from 20 degrees to the maximum of 68 deg at the rate of 7.5 deg/sec. This is reduced to just over 4 deg/sec at a loading of 7.5 gs. The wing sweep obviously moves the CL backwards to the point that the CL is well aft of the CG. This causes a download moment which must be counterbalanced with the horizontal tail. This in turn causes excessive stability at super sonic speeds which reduces maneuverability. Because of the pancake the lifting area of the Tomcat is about 40% greater than the defined wing area which reduces bending moments in both wings and fuselage. It also produces an effective wing loading vastly lower than the reference wing loading. Experienced pilots transitioning from the F8 and F4 called the Tomcat amazingly controllable, easy and vice free when it came to flying the Tomcat. The F4 could be difficult at low speeds, high loads and high AOA or any combination of the three.

 

[drgondog]

The B-17's wing produces less lift more drag pr. area than the U-2's wing, first of all because of it's lower AR, making it a less efficient wing than the U-2's. Furthermore the engine placement on the B-17's wing disturbs the span wise lift distribution over it and creates additional drag, both induced and parasite drag, making it even more inefficient.

Soren - you missed the point in contrasting U-2 to B-17 with lower wing loading and lower aspect ratio, and contrasting the U-2 with a B-29 which had a higher wing loading and higher aspect ratio.

You keep trying to tie 'efficiency' of a wing to a nebulous concept of stream tube whose diameter is the same as a wing span - then traipse off into concepts not in fact, and forgetting what you demonstrated you once knew.

Namely -
1. Induced Drag = drag created by the lift acting on the airfoil.
The equation for induced drag is independent of span.
It is (1/k)^^2*CL^^2/(pi*AR*e) where 1/k = 1/2*rho*V^^2. At same altitude and engagement speed 1/k may be removed from the comparisons to arrive at proportional relationships.

2. The CL of all these a/c at the same engagement speed, same altitude and same place is proportional to:
F-14 Extended Wing -----> CL proportional to L/S ---> 61,000/565---> 108
F-14 Swept Wing --------> CL proportional to L/S ---> 61,000/565 ---> 108
Wing area the same but one swept and one not)
AR=2.55 and 7.2

F-15 Wing ---------------> CL proportional to L/S --->44,500/608 ----> 73
AR=2.9

F-16 Wing ---------------> CL proportional to L/S --->26,500/300 -----> 88
AR=3.4

This says nothing about L/D of the respective ships or the 'efficiency'

3. Back to 1. to compare CDi for each ship at same entry speed, altitude and location (drop 1/2*rho*V^^2 as they are all the same. If 'e' is approximately the same for swept, then"

CDi is proportional to CL**2/(pi*AR)

F-14 Induced Drag proportional to (108^^2)/AR = (108^^2)/2.55----> 4574
F-14 Induced Drag for extended (108^^2)/7.2------> 1620

F-15 Induced Drag proportional to (73^^2)/AR = (73^^2)/2.9 -------> 1837

F-16 Induced Drag proportional to (88^^2)/AR = (88^^2)/3.4 -------> 2277

So, for these simplistic events, level, same altitude, same entry speed, same relative wing efficiency factor 'e'.

The F-14 in lower speed range with extended wings has ~ 88% CDi of F-15 and 71% of the F-16 -

With Swept wings the F-14 is at a huge disadvantage to both the F-15 and F-16 with ~ 4574/1837 ~ 2.48 x CDi of F-15 and 4574/2277 ~ 2.0 x Cdi of the F-16.

This helps a little bit as we know that the swept wing F-14 has a lot more induced drag at the same velocities of the other two ships, but -

CD parasite should dominate higher speeds including even 350kts range but your thesis has been all about vortex strength/tip vortex advantage of the F-14 because of a 'larger stream tube' presumably of the extended wing and it has NOTHING to do with span but everything to do with lift loading and aspect ratio - IF
the Cl/Cd for all the a/c are equal.

If not the case you have to look at the data for each ship carefully to predict performance.

Induced Drag is all about the drag created by Lift. The 'downwash' vector is all about the strength of the circulation, the characteristics of the spanwise lift distribution and the effects of a three dimensional wing. If you look at most CL/CD polars and/or the d(CL)/d(AoA) slope ( the derivative of CL with respect to AoA) , the effects of AR between 1 and say 5 are very significant in improving the slope, beyond that the increase of the CL slope is not changed so much with increases in AR.. You'll find that to be true if you examine a lot of airfoil data corrected by AR. Airfoil section data absent AR corrections is for a 'perfect wing' of infinite AR and no induced drag.

If you don't KNOW L/D for each then you can only speculate from your belief system which a/c is 'more efficient'. That was why I drew you into a discussion comparing different a/c with same wing span but different Lift Loadings at 1 g, as well as different a/c with different (but reversed) AR and Lift Loadings.

But please apply your stream tube philosophy to calculate wingefficiency, induced drag and manuever relevance.

 

[Soren]

You keep trying to tie 'efficiency' of a wing to a nebulous concept of stream tube whose diameter is the same as a wing span - then traipse off into concepts not in fact, and forgetting what you demonstrated you once knew.

Nope, I never tied span loading to efficiency, that again is putting words into my mouth. The span loading is according to some a good indicator of a/c turn performance, that is all I said.

Oh and about your comparison between the F-14, -15 -16, you missed the fact that the effective wing area of the F-14 is much larger than that of the others because of it's lift body design I mentioned earlier in this thread, approx. 40% greater as renrich says.

 

[Soren]

Once inside the merge, what did he say about the final outcome?

B&Z is the magic word FLYBOYJ. The F-15s took the fight into the vertical and beat the F-14s.

Like Krieghund says:
"Once the F-14s were at medium range the F-15s closed the gap for lunch even though the F-14 had a better Instantaneous turn rate but the F-15 retains energy a bit better and It's all over."

Agree on the -16. When you mention Tiger, are you talking about the F-5?

Yup.

Krieghund, are the F14s in your example F14As or F14Ds with the GE engines? I have rather an extensive and comprehensive reference on the F14A with some information about the GE engines and the "Super Tomcat." Here are some interesting data: In level flight the automatic wing sweep causes the sweep to go from 20 degrees to the maximum of 68 deg at the rate of 7.5 deg/sec. This is reduced to just over 4 deg/sec at a loading of 7.5 gs. The wing sweep obviously moves the CL backwards to the point that the CL is well aft of the CG. This causes a download moment which must be counterbalanced with the horizontal tail. This in turn causes excessive stability at super sonic speeds which reduces maneuverability. Because of the pancake the lifting area of the Tomcat is about 40% greater than the defined wing area which reduces bending moments in both wings and fuselage. It also produces an effective wing loading vastly lower than the reference wing loading. Experienced pilots transitioning from the F8 and F4 called the Tomcat amazingly controllable, easy and vice free when it came to flying the Tomcat. The F4 could be difficult at low speeds, high loads and high AOA or any combination of the three.

Yes, the lift body design.

 

[kool kitty89]

Did the F-15 or F-16 benefit from a "lifing body effect," either intentional or not? The fuselage of the F-15 looks particularly similar to that of the F-14.

 

[FLYBOYJ]

B&Z is the magic word FLYBOYJ. The F-15s took the fight into the vertical and beat the F-14s.

Amd they'll do it every time if an engagement is played out within the merge and the F-15 driver knows what he's doing (which again would be most of the time). Again the F-14 was a great fleet defender and bomber killer and it could take on some fighters and win most of the time, it its not going to consistently win against an F-15 and I think that was clearly shown.

 

[krieghund]

renrich: The F14s at ACEVAL/AIMVAL of course were 'A' models with AWG-9 instead of APG-71. My data does show maked manuverability of the 'D' over the 'A' but when it uses it's body lift with an equivalent wing area of over 1000 ft2 it is still too heavy but it does have a high instantaneous turn rate. However one point is when then wings are at a sweep of 45 deg or less it is an indicator of a low energy state and a give away. The F-14 was one of the first so-called spin proof aircraft. It was a fine aircraft that could things others couldn't do. Sometimes these comparisons can be over the top....kinda like, " a Spit is far more manuverable than a P-51!!----Oh, yeah, will do it over Berlin---Nah Nah!!!.

Since the F-14 is now History except for the some quantity in the Iranian AF and the half dozen with the Russian AF I might as well put its numbers up. I will check with my ITAR rep to make sure....the fine is 10 years or $10M or both for ITAR violations.

 

[drgondog]

Nope, I never tied span loading to efficiency, that again is putting words into my mouth. The span loading is according to some a good indicator of a/c turn performance, that is all I said.

Babble from your post #46

"True, but the F-14's wings are more lift efficient, creating more lift pr. area when folded out. The span-loading, which is a good indicator of turn performance according to some as an a/c rides on a cylindrical tube of air, suggests that the F-14 is the best."

Then more babble regarding cylindrical stream tubes in context of drag

??????

Please help me understand your defintion of 'efficiency'.. and your source for 'Span Loading is a good indicator of turn performance" then the extract on stream tubes and relevant change of momentum due to difeerent lift forces...



Oh and about your comparison between the F-14, -15 -16, you missed the fact that the effective wing area of the F-14 is much larger than that of the others because of it's lift body design I mentioned earlier in this thread, approx. 40% greater as renrich says.

Lift due to Wing/Wing area and lifting body contribution are separate concepts. Lifting body contributions are nice at high AoA but also create a lot of drag - in general far less efficient with respect to L/D than the wing

I didn't 'miss' it Soren.

The simple fact is that all three have characteristics of fuselage design to contribute as a lifting body in high AoA. I didn't fool with this part of the discussion because I don't have the data - a 'fact based' thingy - and neither do you. This represents your usual tactic of being confronted on BS and bringing more 'stuff' with no facts to reinforce your earlier BS.

So what is your data/sources to make the statement/claim for both the lifting body contrasts as well as the associated L/D to prove your claim?

Further we didn't have data on the actual Cd0 for subsonic and supersonic profiles to help us talk about energy bleed in high G manuevers. Nor has anyone presented the wing/body L/D for 'true efficiency' for any of these birds or wave drag characteristics or a whole lot of other stuff.

What we believe we do know is that for the F-14 wing fully extended it has a slightly lower Lift Loading than the F-15 and F-16... but dramatically Higher when fully swept. We know the F-14 has a significantly lower T/W, can't accelerate or climb with either of F-15 and F-16.

As a result, based on proportional Lift loading we know that Induced Drag for extended F-14 wing is lower than F-15 and F-15 but the swept F-14 wing has much higher Induced Drag than either of the other two.

We do know that from a base reference, higher lift/sq ft value translates to Higher Lift loading and further translates to higher Induced Drag.

So Soren - lay out your assumptions and facts and demonstrate that the F-14 is superior in the Horizontal if you wish.

If you choose to use a free body diagram with weight, thrust, drag - make sure we understand the difference between initial turn rate and sustained turn rate at max G - and do it for at least one subsonic and one medium supersonic flight profile. Further, make sure the Cd0 and Cdparasite is factual for the velocity and required AoA in both flight regimes.

If you have that, you have a reasonable set of data to do a rough model. With a reasonable model based on factual data and appropriate flight mechanics calculations you will be in a position to at least lend credibility to your claims and Thesis.

We know the ceiling of the F-15 is much higher than the F-14 and was designed for 9G's (as well as F-16).

What we do have I presented for you above, as well as a little background on Induced Drag and how it relates to not only AR but also Lift Loading - but not span per se except for the definition of AR. (AR=span^^2/area of wing)

Fire away

 

[drgondog]

Did the F-15 or F-16 benefit from a "lifing body effect," either intentional or not? The fuselage of the F-15 looks particularly similar to that of the F-14.

Yes - but I sure don't have the data.

 

[SoD Stitch]

Yes - but I sure don't have the data.

I don't have the figures at my fingertips, but I know the "nodding" intakes on the F-15 actually provided a substantial amount of lift when they were in the "up" position, and also at high AOA; this is part of the reason the Israeli pilot was actually able to land his a/c after losing almost all of his right wing in an air-to-air collision with an A-4 in 1983.

 

[drgondog]

I don't have the figures at my fingertips, but I know the "nodding" intakes on the F-15 actually provided a substantial amount of lift when they were in the "up" position, and also at high AOA; this is part of the reason the Israeli pilot was actually able to land his a/c after losing almost all of his right wing in an air-to-air collision with an A-4 in 1983.

I remember that - didn't know the 'technical reason' he was able to maintain control but I do believe that is the single greatest feat of pilot skill that I recall.

 

[Matt308]

The ability to recover that IAF F-15I was not solely based upon aerodynamic qualities and pilot skill (though certainly most impressive). My understanding is the F-15 FCS contains algorithms that allow some rudimentary adaptation of the flight control logic. This allowed the FCS to assist in the modification of control surfaces positioning to match commanded pilot input. As a result of these and similiar incidents (F-18 losing vertical fin and Souix City DC-10 comes to mind), a more focused research has been (publicly) untertaken to ascertain better large scale damage tolerance via FCS/FADEC integration.