Why Red Flag exercises are not indicative of aircraft performance

Where did you get the figure that small inlet reduce thrust by 2000 lbs ?

F-110GE 129 produce 29500 pounds of thrust so there no way F-16N have more thrust than F-16 block 50/52

And what is the weight of F-16N ?

Anyway F-16N is lighter so it will have better ITR but it doesn't necessarily have better STR because STR is factor of drag as well ,and while F-16 have exactly the same outer aerodynamic , it will have less thrust to fight again drag

Difficult to say how much it reduced thrust by - in actual flight the Small Inlet Block 30 only suffered in a few areas according to someone who flew both IIRC - it wasn't a lot less.

The original Block 30s were around mid 17,000 lbs empty so probably not far off what Hummingbird stated.

Yes would concur with the last bit.

Pretty certain they wouldn't be recording HUD footage with pippers in an airshow, also Airshows take place close to sea level so the crowd can see the action where'as actual mock fights usually take place at 10,000 ft and higher.

Why wouldn't they? One of they easiest way to track aircraft you are trying to form on would be to use the RADAR. They wouldn't carry weapons (or bullets for the gun) so no fear of accidental firing. The F-16 AVTR are always carried and always record, great tool for debrief. About the altitude, mock fight can't happened at lower altitudes? So no one ever hit the safety Hard deck? Of course they can and it happens.

My point is videos and photos are not always the best way to tell without context. We could not tell the difference, I wouldn't be able to. One training scenario could be aircraft X start at 6 o'clock while aircraft Y tries to shake it off, we could not tell that from a HUD video. We would not be able to tell the Pilots experience and many other factors for that specific training scenario.

Or didn't want to spend money preventing it :)

 

I can find out but are you aware of any other F-16 types that skipped initial structural testing for a mod like this?

 

 

Previous post above was actually back OT - fancy that :)

No I do not know, but I'm sure someone in F-16.net will probably have complete knowledge.

I read what you wrote and my opinion is that it is irrelevant

Because the F-15 would not fly at the F-14 corner speed so that itself turn slower , and the F-14 won't turn at F-15 corner speed either , hence the correct way would be to compare their respective Max sustainable turn rate

To say it is irrelevant shows a massive lack of understanding how to win a turn fight. In a turn fight you want the right combination of rate and radius as this is what will allow you to turn inside your opponent and get guns on target.

I don't underestimate the important of speed in turning

 

Corner speed of F-16 at 10k feet and DI 50 is around mach 0.84-0.85 too and it's sustainable G is lower than F-15 almost 1G , there aren't no way F-15 Max sustainable turn rate is less than F-16 and F-14 in that situation

Measure it if you want

turn rate = [1091*tan(bank angle)] /[true air speed in knots]

G-load is 1/cos( bank angle)

I had a feeling you might come up with a claim like that, hence I left out the lower part of the F-15 chart from the start:

Max STR 14 deg/sec @ Mach 0.85.

In short you need to check your math ;)

Wing loading of F-14 is around 468 kg/m2 that is higher than F-16 and much higher than F-15

Along with the fact that F-16 have LERX it will have better CL value at AoA compare to both F-14 and F-15

Incorrect. The F-14's actual wing loading, or should we say weight to lifting surface ratio, is infact lower than both the F-16 and F-15's thanks to its blended lifting body design, the entire fuselage being shaped in the form of an airfoil.

The F-14 is essentially a giant wing in itself:

This in addition to its own LERXs as well as full span LE camber increasing slats and swing wing which helps optimize the lift/drag ratio with speed, is what allows the F-14 to generate more lift pr. weight than either the F-16 or F-15, and the direct reason behind the noticably higher ITR from top to bottom.

Explanation from one fo the designers themselves at 16:40 min:

SsUCixAeZ0A

And you cannot just draw or connect an imagine max turn rate line , they are not liner , and aircraft don't turn at the same AoA at all speed , different wing configuratition lead to very different CL , Cd and stall AoA

You actually think the lift line just stops?? :megalol: Sorry mate but a lift line doesn't just stop, it keeps on going and in the case of the F-14 it keeps going in roughly the same way/curve until Mach 0.85, infact it steepens until that point, thus the max rate at 9 G might very well be 25 deg/sec instead of 24 deg/sec for the F-14.

Here you can observe the F-14's lift curve until 7.5 G's at 35,000 ft, as you can see it not only keeps going it infact steepens along the way until it reaches Mach 0.85 at which point it experiences a small notch and then continues along a slightly shallower curve:

Therefore as mentioned the F-14 boasts a superior ITR compared to the F-15 & F-16 across the entire speed range. Also you will notice that the STR does not experience any sudden drop off along the speed range, again proving that the F-14 doesn't experience any appreciable drop off in lift at high speeds, infact its STR is slightly superior to that of the F-16 & 15 above Mach 1.2.

What F-14 have over F-15 and F-16 is that it can swing it's wing out at less sweep angle hence it turn very good at slow speed, but that won't happen at faster speed

Sorry but you're incorrect, as the chart above proves. At higher speeds the F-14 benefits from the delta planform it assumes, allowing it to maintain a favorable lift/drag ratio.

Hummingbird , it doesn't matter if you repeat it , because it only your words and your guess is only as good as mine

The problem is the flight manual limited F-14 to 6.5G as well and even F-14 pilot admited his aircraft is limited to 7.5G

You have to see it from my point of view " why should I trust you more than the flight manual and pilot word " ?

Thing is I'm not guessing gyarra, I'm using hard facts straight from the manual. You on the other hand are guessing, and its not been going well so far.

Just post the turn rate graph for F-14 at sea level or 5000K feet then we will see

You do realize that this manual isn't very easy to get and it actually took a little trouble for the person I bought it from to get his hands on, right?

Hence this is the last freebe you're going to get garrya, if you want more you will have to find and buy the manual yourself (the forum member called Lunaticfringe will likely sell you a copy):

Why would you think F-14 can easily take 9g while the manual andt say otherwise ?

Because the manual doesn't say otherwise, and because the ultimate load limit is the same as that of the F-15! The operational load limit is there to increase airframe longevity, hence it changes depending on the projected service life pr. airframe!

Turn rate doesn't work like that as explained before

That is exactly how it works, however you may think it works is a different matter :D

What I mean by older suits is that newer suits like Combat Edge are potentially better and allow pilots to get to 9G easier than previously.

 

Probably the wrong route to take - you can have all kinds of what ifs.

 

 

If talking about aircraft performance and capability - surely in Red Flag today performance of aircraft sensors, information management and how they work with other Blue assets is more important IMO :thumbup:

No disagreement there :) Also in which case it wouldn't do any harm to have an extra set of hands & eyes in the cockpit, hence why I feel the F-14 still had a lot of growth potential left in it, atleast as much as the F-15 :)

I always thought it was a major mistake to cut orders short and shut down production for the Tomcat back in the day. But we've reached the point where soon all the legacy fighters will be superceded by newer designs anyway, so it's not a disaster. It's just unfortunate for the Navy that it will lack some of the capability the F-14 provided until its 5th gen replacement shows up.

To say it is irrelevant shows a massive lack of understanding how to win a turn fight. In a turn fight you want the right

all F-15 , F-16 pilots that asked said STR , speed and climb ability (t/w ) are important in dogfight , depending on situation they can trade speed or altitude or altitude for speed , or speed and altitude for turn rate

nose pointing is also mentioned that they can be useful in some situation

but I have never talked to any pilot that say turn radius is very important or that he will trade both speed , and turn rate for smaller turn radius

Incorrect. The F-14's actual wing loading, or should we say weight to lifting surface ratio, is infact lower than both the F-16 and F-15's thanks to its blended lifting body design, the entire fuselage being shaped in the form of an airfoil.

F-15 and F-16 have body lift design too

there is a case when F-15 able to fly back to base with 1 wing completely broken

about F-16 , it have 40% lift from the body

The leading edge extensions just under the canopy have a significant area for lift and also help contain pressure on the underside of the fuselage to keep it from flowing up the sides. That effect is called carry-over. That means there is pressure on the fuselage under surface due to the presence of the leading edge extensions. Lets say that under some condition there is a 2 psi pressure on the lower surface of the fuselage, contributing to body lift. If we remove the leading edge extensions, the pressure drops to 1 psi, reducing body lift. The wing/fuselage intersection is heavily blended, resulting in reduced interference drag and increased carry-over pressure on the fuselage from wing lift, similar to the leading edge extension carry-over effect. Next look at the rectangular beams running down the fuselage sides from the wings past the horizontal tails, including the speedbrake. The lower surface of those beams is almost flat and allows a large area for pressure to create body lift. Next, the horizontal tails also produce a carry-over lift on the aft fuselage. . Then finally, the F-16 speedbrake has an exposed flat area to help with body lift. Wait, there is one more body lift contributor, the ventral fins. With AoA, there is an outboard acting load on each fin, which has a vertical component because the fins are canted outboard 15 degrees. Also, air trapped between the fins pushes up on the fuselage for more lift.

 

Add all those F-16 body lift contributors and you have as much as 40-45% of total lift on the airplane from the fuselage. There are serious improvements in airplane performance due to that lift. (1) Less wing lift required - smaller, lighter wing. (2) Lower AoA required - less drag. (3) Primary structural load on fuselage is down inertia load from vertical acceleration due to g. Up air pressure load (body lift) reduces the structural load on the entire fuselage - less weight, less lift required per g, even lower AoA and drag. It is a big deal, truly, in improving performance.

another advantage of F-16 over F-14 and F-15 is the negative stability design , which mean it's tail fin contribute to total lift rather than counter it

Pitch stability is mostly the result of the relative location of the center of gravity to the center of lift. A stable airplane has the CG forward of the lift center, while the opposite is true for an unstable airplane. For stable, added lift from increased AoA causes the nose to pitch down, reducing AoA and g. So to increase g, the tail must push down with enough positive pitch moment to overcome the negative pitch moment of lift aft of the CG. That down tail load must then be overcome by added wing/body lift (more AoA, drag, structural load in wing, weight) to get the desired g.

 

For the unstable airplane, wing/body lift is forward of the CG, so with increased AoA, the nose pitches up, increasing AoA and g. Left alone the airplane would pitch up out of control, with structural failure probable. So the horizontal tail, must push up to prevent that from happening and maintaining the desired AoA and g. The up load on the tail reduces the required wing/body lift (less AoA, drag, structural load on wing, weight) to reach a desired g. The unstable airplane is also truly a big deal in improving performance

This in addition to its own LERXs

F-14 doesnot have Lerx , it have gloves vane ( btw F-14D doesn't even have the gloves vanes ) that thing have very different purpose from a LERX

here is gloves vanes

LERX need to be sharp enough to create vortex

Concerning the F-15 LERX question, the surface just inboard of the wing leading edge might resemble a LERX, but it isn't really, due to its large radius leading edge. A LERX should have a highly swept, sharp leading edge to generate a vortex. The sharp edge causes the air to separate from the upper surface and curl over to begin the vortex. The large radius F-15 leading edge is highly swept, but allows the air to remain attached to the upper surface, thus no vortex. F-111 and F-14 have similar highly swept, large radius leading edges just inboard of the wings

F-16 create thick vortex like this even at high AoA

as well as full span LE camber increasing slats and swing wing which helps optimize the lift/drag ratio with speed, is what allows the F-14 to generate more lift pr. weight than either the F-16 or F-15, and the direct reason behind the noticably higher ITR from top to bottom.

at low speed the wing sweep angle of F-14 is less than either F-15 and F-16 hence it provide bigger Cl value hence superior lift and from that come the instantaneous turn rate

however at higher speed F-14 doesnot enjoy that advantage anymore because it's wing now have to sweep back so it face the same situation as F-16 and F-15

You actually think the lift line just stops?? :megalol: Sorry mate but a lift line doesn't just stop, it keeps on going and in the case of the F-14 it keeps going in roughly the same way/curve until Mach 0.85, infact it steepens until that point, thus the max rate at 9 G might very well be 25 deg/sec instead of 24 deg/sec for the F-14.

Here you can observe the F-14's lift curve until 7.5 G's at 35,000 ft, as you can see it not only keeps going it infact steepens along the way until it reaches Mach 0.85 at which point it experiences a small notch and then continues along a slightly shallower curve:[/

no one say the line just stop , it continues but it steepness change because the wing sweep angle of F-14 change as it go faster ( Cl value isnot the same anymore )

In conclusion you cannot just added the line as you like into the graph , if such things was possible then testing aircraft for all speed range wouldn't be necessary anymore

Also you will notice that the STR does not experience any sudden drop off along the speed range, again proving that the F-14 doesn't experience any appreciable drop off in lift at high speeds,

STR is more complicated because you have to take drag , thrust into consideration too , and the sustain turn rate of F-14 reduce a lot after mach 0.55 which mean that either it's engine doesn't provide enough thrust to fight again the drag increase or that at higher speed the wing sweep back so doesn't provide F-14 with as much lift anymore

infact its STR is slightly superior to that of the F-16 & 15 above Mach 1.2.

well no it isn't

For example at mach 1.2 the STR of F-15 is 5.5 degree/ second

, the STR of F-14 is around 5.3 degrees/ second

but the F-16 STR is about 8 degree/seconds

Thing is I'm not guessing gyarra, I'm using hard facts straight from the manual. You on the other hand are guessing, and its not been going well so far.

Because the manual doesn't say otherwise, and because the ultimate load limit is the same as that of the F-15! The operational load limit is there to increase airframe longevity, hence it changes depending on the projected service life pr. airframe!

Hummidbird the EM graph from manual you posted literally have the 6.5G limit line on it , and there others part in the manual mentioned the limit as well

If excess the limit only reduce the service life and doesn't have any destructive effect then there would be some guide in the manual about it , but here there is no thing , they don't even draw the line above 6.5G

Also F-14 isn't the only aircraft that have structure limit , all other airframes have it too depending on how much weapons they carry

The F-15 have a Vmax switch that can reduce service life of Its engine significantly too but there is detail guide in the manual about how to use it in specific situation

On a side note about F-16 using GE and F-16 using PW engine

F-16 with GE engine and big inlet can turn much better

Vs

On a side note about F-16 using GE and F-16 using PW engine

F-16 with GE engine and big inlet can turn much better

Be careful there - note the 2,000 lbs weight difference between the charts - and look at GW effect in the chart.

F-15 and F-16 have body lift design too

there is a case when F-15 able to fly back to base with 1 wing completely broken

about F-16 , it have 40% lift from the body

Every fighter design produces some body lift, however neither the F-15 nor the F-16 benefit from this to anywhere near the same extent of efficiency as the F-14. The F-14 is a true lifting body design and takes the concept a lot further with its widely spaced nacelles and entire fuselage cross section being the shape of an airfoil; the benefits of which are obvious, as we see on the lift curves.

Now regarding LERX, there's no doubt that among the three aircraft in question the F-16 enjoys by far the most from this effect, but the sharp leading edges on the upper part of the F-14's engine inlets were actually designed with the same effect in mind in order to increase Cl of the outer fuselage section & wings (which as mentioned was designed for maximum lift) and also generates these vortices at high AoA's:

Thus the F-14 enjoys some benefit from this effect as well, albeit nowhere near to the same extent as the F-16, instead the F-14 relies on its huge airfoil shaped lifting body & swing wing to increase its overall lift. Finally the F-15 hardly if at all experiences the vortice effect.

no one say the line just stop , it continues but it steepness change because the wing sweep angle of F-14 change as it go faster ( Cl value isnot the same anymore )

 

In conclusion you cannot just added the line as you like into the graph , if such things was possible then testing aircraft for all speed range wouldn't be necessary anymore

I am not adding any line, I am looking at the actual measured lift line as presented to you:

As can be seen the lift curve steepens until M 0.85, after which point it experiences a slight notch (transonic effect) and then continues again in a slightly shallower curve. Following this lift curve shows that the F-14 enjoys a noticable ITR advantage over both the F-15 & F-16 at all speeds, which is not surprising considering that it was designed speficially around generating as much life as possible from the airframe.

well no it isn't

For example at mach 1.2 the STR of F-15 is 5.5 degree/ second

Here you are for once at least partially correct as I must have accidently read the -100 line, but the F-15 infact turns at 6 deg/sec (not 5.5) and the F-14 at 5.5 deg/sec (not 5.2) @ Mach 1.2 :

None of this changes anything in terms of dogfights though as these don't take place at supersonic speeds, and the F-14 is superior to the F-15 in STR up to Mach 0.74, also featuring a smaller turning circle and boasting a noticably higher ITR at all speeds, allowing it to at any point turn inside the F-15's turning circle. Thus in a mock dogfight with the F-14 the F-15 will have to go vertical or face quickly being outmaneuvered and virtually shot down, and this is exactly what F-15 pilots would attempt to do when faced with the F-14 or any other tight turning but slower climbing adversary.

If excess the limit only reduce the service life and doesn't have any destructive effect then there would be some guide in the manual about it , but here there is no thing , they don't even draw the line above 6.5G

The F-15 have a Vmax switch that can reduce service life of Its engine significantly too but there is detail guide in the manual about how to use it in specific situation

No the manual would not mention it because the manual has to list the operational limits, not the actual ultimate design limits. Hence why there's also a "projected" limit line on some of the charts incase the Navy decided to increase the operational limit to the 7.5 G's that Grumman expected based on standard airframe longevity standards whilst taking into account the extra stresses involved with carrier operations.

But as mentioned several times by now the ultimate load limit of the F-14 was the same as that of the F-15. Infact the F-14 was tested a lot more rigorously to precisely establish the limits of the airframe, Grumman committing an unprecented number of aircraft to stress testing. The F-14 airframe was stressed over 14 G's on the bench, and later flight tested to 13 G's without incident. Grumman wanted to make sure the thing could last!

However due to the F-14 having to operate off of an aircraft carrier this also meant that the airframe would be put under a lot higher stresses on a daily basis than would any Army airforce fighter. Thus the space between the design ultimate load limit and the operational load limit had to be wider in order to ensure a similar airframe longevity as an army plane.

Hence Grumman at first counted on the Navy setting the limit at 7.5 G's (the projected limit you see on the charts), some 1.5 G's lower than the F-15 in order to accomodate for the higher daily stresses endured operating from an aircraft carrier. However this would change yet again as F-14 orders were suddenly cut short, which in turn meant that the airframes already purchased suddenly had to last even longer, resulting in the Navy first reducing the load limit to 7 G's and then later to 6.5 G's.

Really garrya? :D : http://www.f-16.net/forum/viewtopic.php?f=30&t=28783&p=313148

Be careful there - note the 2,000 lbs weight difference between the charts - and look at GW effect in the chart.

Hmm where that 2000 lbs come from ? :huh: could that be from the weight of the CFT ? A bit confuding when in the manual of HAF F-16 they listed engine kind as PW F-100/CFT

Really garrya? :D : http://www.f-16.net/forum/viewtopic.php?f=30&t=28783&p=313148

Yes , because i want to hear from some expert , i alway cross check between forums

Hmm where that 2000 lbs come from ? :huh: could that be from the weight of the CFT ?

 

The charts only show performance for a single weight / DI / altitude / engine type.

The F-110-GE-100 is used by the Block 30 & Block 40 only - so if for example the Block 40 has an empty weight of 19,000 lbs, then once you add the fuel weight (~7000 lbs), pilot, ammo etc it's take off weight would be around 27,000 lbs.

Every fighter design produces some body lift, however neither the F-15 nor the F-16 benefit from this to anywhere near the same extent of efficiency as the F-14. The F-14 is a true lifting body design and takes the concept a lot further with its widely spaced nacelles and entire fuselage cross section being the shape of an airfoil;

Without actual measurement i dont think you can concluded which fighter benefit more from body lift

Especially in the case of F-16 it have significant advantage from negative stability design and LERX

You can argue that F-14 benefit more from body lift than F-15 but then again F-15 already have much lower wingloading (reference wing area )than either F-14 ,F-16

If F-14 have alot more lift /weight than F-16 then it should perform very good at altiude with variable inlet ( which it isnt really )

the benefits of which are obvious, as we see on the lift curves.

The lift curve is high could be the result from the variable geometri wing too , they can be at a smaller sweep angle than F-15 , F-16 hence create more lift at low speed

Now regarding LERX, there's no doubt that among the three aircraft in question the F-16 enjoys by far the most from this effect, but the sharp leading edges on the upper part of the F-14's engine inlets were actually designed with the same effect in mind in order to increase Cl of the outer fuselage section & wings (which as mentioned was designed for maximum lift) and also generates these vortices at high AoA's:

Thus the F-14 enjoys some benefit from this effect as well, albeit nowhere near to the same extent as the F-16, instead the F-14 relies on its huge airfoil shaped lifting body & swing wing to increase its overall lift. Finally the F-15 hardly if at all experiences the vortice effect.

F-15 have very sharp intake too ( i would say not that much different from F-14 )

And I dont think the picture is really the vortex in the form that F-16 LERX created , it look more or less like the water vapor that appear when you turn at high speed , there a similar thing happen to F-15 but with larger scale

I am not adding any line, I am looking at the actual measured lift line as presented to you:

 

 

 

 

As can be seen the lift curve steepens until M 0.85, after which point it experiences a slight notch (transonic effect) and then continues again in a slightly shallower curve. Following this lift curve shows that the F-14 enjoys a noticable ITR advantage over both the F-15 & F-16 at all speeds, which is not surprising considering that it was designed speficially around generating as much life as possible from the airframe.

Iam not saying you draw the lift line , surely total lift increase as aircraft go at higher AoA and higher speed , whether the aircraft can stand that or not is another thing

i said you draw the ITR line which are not in the manual and clearly excess the structure limit , if you want aircraft to turn pass the structure limit tgen why only do that to F-14 ? Why not F-16 ? Why not F-15 It's graph is limited at 9G line too , and how about AoA limit ...etc

Here you are for once at least partially correct as I must have accidently read the -100 line, but the F-15 infact turns at 6 deg/sec (not 5.5) and the F-14 at 5.5 deg/sec (not 5.2) @ Mach 1.2 :

None of this changes anything in terms of dogfights though

Yes but it does benefit at BVR because pilot often accelerate pass mach 1 before lauching their missiles at enemy , a better high speed sustain turn rate help in that case if you want to reduce closuare rate of enemy missiles while dont want to waste all energy making a bat turn

, and the F-14 is superior to the F-15 in STR up to Mach 0.74, also featuring a smaller turning circle and

Which doesnt matter because that not the corner speed of F-15 , there is no reason for F-15 pilot to slow down and reduce his turn rate and energy

Let put it simply this way , A piston fighter like zero or spitfire will easily have much better turn rate than any jet at slow speed , if you pilot a jet fighter and have to fight a piston fighter would you slow down and fly with them in their corner speed ? Or will you accelerate to vertical ( or at least your own corner speed )?

, allowing it to at any point turn inside the F-15's turning circle. Thus in a mock dogfight with the F-14 the F-15 will have to go vertical or face quickly being outmaneuvered and virtually shot down, .

You forgot to mention that after making the hard turn if the F-14 pilot fail to shot down F-15 ,F-16 adversary ( which is not easy at alll because F-15 roll very fast and F-16 roll even faster )then the F-14 will deplete most of its speed and become and easy target

F-14 best ITR is at around mach 0.55 when it is already slow , the PS of the turn is -1000 , it would be very sluggish after that turn , not much better than X-31 when stalling

Actually as shown in WW II turn- burn fighter does do so well again zoom-boom fighters

No the manual would not mention it because the manual has to list the operational limits, not the actual ultimate design limits. Hence why there's also a "projected" limit line on some of the charts incase the Navy decided to increase the operational limit to the 7.5 G's that Grumman expected based on standard airframe longevity standards whilst taking into account the extra stresses involved with carrier operations.

 

But as mentioned several times by now the ultimate load limit of the F-14 was the same as that of the F-15. Infact the F-14 was tested a lot more rigorously to precisely establish the limits of the airframe, Grumman committing an unprecented number of aircraft to stress testing. The F-14 airframe was stressed over 14 G's on the bench, and later flight tested to 13 G's without incident. Grumman wanted to make sure the thing could last!

 

However due to the F-14 having to operate off of an aircraft carrier this also meant that the airframe would be put under a lot higher stresses on a daily basis than would any Army airforce fighter. Thus the space between the design ultimate load limit and the operational load limit had to be wider in order to ensure a similar airframe longevity as an army plane.

 

Hence Grumman at first counted on the Navy setting the limit at 7.5 G's (the projected limit you see on the charts), some 1.5 G's lower than the F-15 in order to accomodate for the higher daily stresses endured operating from an aircraft carrier. However this would change yet again as F-14 orders were suddenly cut short, which in turn meant that the airframes already purchased suddenly had to last even longer, resulting in the Navy first reducing the load limit to 7 G's and then later to 6.5 G's.

You know what , we are going in circles now and it rather tiring for both

There is no way for you to convince me that F-14 have G limit similar to F-16 , F-15

And there is no way for me to convince you otherwise

So how about just let it at there and agree to disagree ? If there is suddenly some actual pilot come and state his opinion about this then fine we can continue ,

Without actual measurement i dont think you can concluded which fighter benefit more from body lift

Especially in the case of F-16 it have significant advantage from negative stability design and LERX

You can argue that F-14 benefit more from body lift than F-15 but then again F-15 already have much lower wingloading (reference wing area )than either F-14 ,F-16

If F-14 have alot more lift /weight than F-16 then it should perform very good at altiude with variable inlet ( which it isnt really )

Finding the body lift itself, alone is hard, but the ITR and weight gives you to the pound how much lift you're making.

F-15 have very sharp intake too ( i would say not that much different from F-14 )

And I dont think the picture is really the vortex in the form that F-16 LERX created , it look more or less like the water vapor that appear when you turn at high speed , there a similar thing happen to F-15 but with larger scale

Yes but it does benefit at BVR because pilot often accelerate pass mach 1 before lauching their missiles at enemy , a better high speed sustain turn rate help in that case if you want to reduce closuare rate of enemy missiles while dont want to waste all energy making a bat turn

Which doesnt matter because that not the corner speed of F-15 , there is no reason for F-15 pilot to slow down and reduce his turn rate and energy

Let put it simply this way , A piston fighter like zero or spitfire will easily have much better turn rate than any jet at slow speed , if you pilot a jet fighter and have to fight a piston fighter would you slow down and fly with them in their corner speed ? Or will you accelerate to vertical ( or at least your own corner speed )?

Without actual measurement i dont think you can concluded which fighter benefit more from body lift especially in the case of F-16 it have significant advantage from negative stability design and LERX

On this point - the F-16 is intentionally prevented from reaching its CL Max by limiters - has nothing to do with lift generation.

The F-14 airframe obviously does generate more lift simply because it has to overcome more weight and drag - so what is important is actual lift to drag / weight which cannot be determined from wingloading.

Hmm where that 2000 lbs come from? A bit confuding when in the manual of HAF F-16 they listed engine kind as PW F-100/CFT

It looks like the first charts are form a F-16C (block 25, 30 or 32) and since only the block 30 uses GE. Now, all these blocks have smaller landing gear and other things that make it lighter.

The second chart is for a CJ, so block 50 and 52. Since only the 52 uses PW engine. The HAF 52 had additional equipment that also makes it a bit heavier. If you look at the first couple of pages of that manual, it will tell you the specific tail number to which it applied to, page vii you can take those numbers to F-16.net and find the specific block. Further more, yes I do believe the CFT are added to the second charts. For the engine, on the PW the 100 comes first and on the GE is last. (F100-PW-229 and F110-GE-100)

The lift curve is high could be the result from the variable geometri wing too , they can be at a smaller sweep angle than F-15 , F-16 hence create more lift at low speed

That what I have been trying to say

It's not the inlets themselves. It's what extends from the sides. The F-15 has fairings that house the gun/refueling system, and while they probably generate a vortex, it's not as strong as the ones on the F-14 or F-16.

The part on the side of F-15 and F-14 are exactly the same , neither is sharp enough to produce vortex like F-16 LERX

I think the subject of debate needs to be defined. If by "dogfight" we mean a head on pass and then turn, then accelerating won't help you very much.

Iam not quite sure what you trying to say but some time pilot use their ITR instead of STR , in that case aircraft will lose a large amount of speed so a fast acceleration rate to regain energy (speed ) is very useful

It all depends on the fight. If there are missiles involved, blindly going vertical won't help the F-15 as the F-14 could still turn inside it and shoot.

That is true , but then in that case with something like AIM-9X and HMD there would be practically little to no different between an F-14 , F-15 or F-16

Corner speed is not the best speed for everything. If the two planes started 10 miles out and were closing to WVR missile range, the F-15 would probably have the advantage with the higher corner speed, but if the two planes pass each other, radius becomes very important.

I really can't imagine the dogfight situation when pilot actually sacrifile his turn rate and speed for turn radius even in you example

And I haven't heard any pilot talk about it either , the closest thing is nose point ng but that is still sacrifile speed for turn rate not turn radius

On this point - the F-16 is intentionally prevented from reaching its CL Max by limiters - has nothing to do with lift generation.

 

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I know limiter prevent F-16 from stalling but an unstable design will benefit when turning because

Pitch stability is mostly the result of the relative location of the center of gravity to the center of lift. A stable airplane has the CG forward of the lift center, while the opposite is true for an unstable airplane. For stable, added lift from increased AoA causes the nose to pitch down, reducing AoA and g. So to increase g, the tail must push down with enough positive pitch moment to overcome the negative pitch moment of lift aft of the CG. That down tail load must then be overcome by added wing/body lift (more AoA, drag, structural load in wing, weight) to get the desired g.

 

For the unstable airplane, wing/body lift is forward of the CG, so with increased AoA, the nose pitches up, increasing AoA and g. Left alone the airplane would pitch up out of control, with structural failure probable. So the horizontal tail, must push up to prevent that from happening and maintaining the desired AoA and g. The up load on the tail reduces the required wing/body lift (less AoA, drag, structural load on wing, weight) to reach a desired g. The unstable airplane is also truly a big deal in improving performance.

That what I have been trying to say

That was an error in quote brackets, sorry.

The part on the side of F-15 and F-14 are exactly the same , neither is sharp enough to produce vortex like F-16 LERX

It doesn't need to be sharp as on the F-16 to produce a vortex. The F-14's advantage over the F-15 is larger area and a flatter surface to generate differences in pressure over. It acts like a small delta wing. The F-15 "LERX" has no flat underside to generate spanwise flow.

Iam not quite sure what you trying to say but some time pilot use their ITR instead of STR , in that case aircraft will lose a large amount of speed so a fast acceleration rate to regain energy (speed ) is very useful

I was saying that accelerating at full power isn't necessarily useful in a traditional head on merge. A lot of the time, speed is life in air combat, but not always. Burning energy by using ITR isn't a bad move if it's likely to get you a kill. In a head on pass with decent missiles, the first plane to turn around will likely win.

The best tactic to use depends on the situation, so for the sake of discussion, we really need to make it clear what specific situation we're talking about, if any.

That is true , but then in that case with something like AIM-9X and HMD there would be practically little to no different between an F-14 , F-15 or F-16

I don't think you would need to go that far. The 9M is probably good enough to make going vertical risky.

I really can't imagine the dogfight situation when pilot actually sacrifile his turn rate and speed for turn radius even in you example

 

And I haven't heard any pilot talk about it either , the closest thing is nose point ng but that is still sacrifile speed for turn rate not turn radius

It's the point of picking one fight circle over two fight circle. It's also how you win in a scissors.

Without actual measurement i dont think you can concluded which fighter benefit more from body lift

Well that's the thing, we do have an actual measurement of the amount of lift to weight generated when the wings are fully swept, which is pretty good indicator ;)

Especially in the case of F-16 it have significant advantage from negative stability design and LERX

You can argue that F-14 benefit more from body lift than F-15 but then again F-15 already have much lower wingloading (reference wing area )than either F-14 ,F-16

If F-14 have alot more lift /weight than F-16 then it should perform very good at altiude with variable inlet ( which it isnt really )

The F-14 does perform well at high altitude? It's ITR is superior accross the board.

The lift curve is high could be the result from the variable geometri wing too , they can be at a smaller sweep angle than F-15 , F-16 hence create more lift at low speed

You don't seem to understand that the lift curve continues to be higher even at the point where the wings are fully swept. It's right there on the charts I provided.

Moving back to vortice effects the F-14 benefits more and more from this as it sweeps back its wings, eventually reaching a delta planform.

You forgot to mention that after making the hard turn if the F-14 pilot fail to shot down F-15 ,F-16 adversary ( which is not easy at alll because F-15 roll very fast and F-16 roll even faster )then the F-14 will deplete most of its speed and become and easy target

 

F-14 best ITR is at around mach 0.55 when it is already slow , the PS of the turn is -1000 , it would be very sluggish after that turn , not much better than X-31 when stalling

The F-14's best ITR is not at Mach 0.55, ITR is dependant on the actual lift to weight ratio thus it increases with increases in airspeed and is only limited by the ultimate load limit of the aircraft. Hence the F-14 features a better ITR than the F-15 or F-16 at any speed, esp. as unlike the other two it features no G limiter.

STR is another matter as it depends as much on thrust & drag as it does on lift.

I know limiter prevent -

Sorry should be more clear - was referring to some of these comments:

Exorcet:

The lift curve is high could be the result from the variable geometri wing too , they can be at a smaller sweep angle than F-15 , F-16 hence create more lift at low speed

 

 

Hummingbird:

Every fighter design produces some body lift, however neither the F-15 nor the F-16 benefit from this to anywhere near the same extent of efficiency as the F-14. The F-14 is a true lifting body design and takes the concept a lot further with its widely spaced nacelles and entire fuselage cross section being the shape of an airfoil; the benefits of which are obvious, as we see on the lift curves.

What I was trying to say was that the F-16 charts do not show how much lift the actual F-16 airframe makes at slow speed because it is prevented from reaching its max lift by an AOA limiter.

To get some idea the F-16 has demonstrated airshow tricks like the cobra etc without the limiter.

I really can't imagine the dogfight situation when pilot actually sacrifile his turn rate and speed for turn radius even in you example

 

And I haven't heard any pilot talk about it either , the closest thing is nose point ng but that is still sacrifile speed for turn rate not turn radius

Most of my dogfight wins in BVR servers happen by me going for aggressive one circle fight and the bandit flies in front of me and gets blasted by gun or missile, depending on how fast he is. It's much easier to force one circle flow instead of two circle flow and with missiles it doesn't matter if the other guy is going gazillion knots with awesome STR as a missile will catch him anyway. Also many modern planes are built to have very good ITR and high alpha capability, presumably for this reason.

I should add that the F-14A with the glove vanes installed featured a higher supersonic STR than the B/D model, doing 6 deg/sec at Mach 1.2.

Here's the 5000 ft chart with the rest of the lift line added as tested by Grumman:

Note: The 9 G line is an approximation.

That was an error in quote brackets, sorry.

It doesn't need to be sharp as on the F-16 to produce a vortex. The F-14's advantage over the F-15 is larger area and a flatter surface to generate differences in pressure over. It acts like a small delta wing. The F-15 "LERX" has no flat underside to generate spanwise flow.

Still un convinced

Never saw an F-14 turn with this much vortex

And according to engineer i talked to , the big radius of the "LERX" on f-15 , F-14 just make the flow curve over instead of create the vortex

I was saying that accelerating at full power isn't necessarily useful in a traditional head on merge. A lot of the time, speed is life in air combat, but not always

Going faster give your missiles more energy (range )does it not ?

T

Burning energy by using ITR isn't a bad move if it's likely to get you a kill.

If it get you the kill then it wouldnt be a bad move , but if it isnt then well

In a head on pass with decent missiles, the first plane to turn around will likely win.

How can you turn around first if you turn slower ?

The best tactic to use depends on the situation, so for the sake of discussion, we really need to make it clear what specific situation we're talking about, if any.

That true

I don't think you would need to go that far. The 9M is probably good enough to make going vertical risky.

9M can still be defeated by flares , and also F-15 , F-16 are fully able to use AIM-9X python-5 and HMD by now so i think if we gonna use missiles it practically the same between all fighter

Look garrya, no'one is saying that the F-14 produces vortices as strong as those on the F-16, it obviously doesn't, but it does produce the effect.

Perhaps this will finally convince you:

From a NASA Flow Visualization Study of the F-14:

"The F-14 model was investigated to determine the vortex flow field development, vortex path, and vortex breakdown characteristics as a function of angle of attack and sideslip. Vortex flows were found to develop on the highly swept glove and on the upper surface of the forebody."

The above is exactly what we see on the picture posted earlier: