Other than some PR advertisment, what is “stealth” datalink, really? Theoratical discussions are good, but I am not aware of anything on any known/projected aircraft that can detect good old TKS-2-27, Lazur, link-16, MIDS etc datalinks let alone capable of detecting and pinpointing the target location.

I see, very interesting, but isn’t JF-17 is same size with F-16?

At 6,5 tons and F-404 class engine (RD-93), its more comperable to Grippen/F-20 than F-16 IMHO.

the point about weight and center of gravity : isn’t LERX is very tiny and small? how could it weight enough to change center of gravity of aircraft ? ( i mean something like refueling probe would look like it would be alot heavier, or CFT look like they are alot heavier too, but they don’t seem to affect fighter alot)

Not center of gravity, but aerodynamic center. Making lerx longer would move lift center to the front. Its bad if your aircraft is already unstable, where elevators would have to increase their lift to compensate for the shift, and very bad if aircraft stalls, forward lift center causes deep stall, without recovery. Both points need enlargening elevators, which themselves are draggy. So why make lerx longer in the first place. Shorter and wider LERX will give same vortex intensity with slightly increased drag (possibly less increase than enlargening elevators). Its both a simpler and better solution, if engineers are not up to designing F-18E from scratch.

BTW since canard alot bigger than normal LERX ( even the one F-16, Su-27) so they are better for maneuver ?

For canards size isn’t much of an issue, as it can rotate to control pressure difference which vortex is generated from. Is canards better for maneuvering? Definately yes for subsonic maneuvering, and maybe for trimming, but it comes with drag for supersonic regime both in level flight and maneuvering, usually without meaningful gains (excluding Typhoon-like canards which is just the opposite). If I were to oversimplify, LERX is shouldn’t cost anything if done properly, its simpler and adds to maneuverability in general. Canards are better in some areas and worse in others. These are additional trade-offs designers have to consider.

thanks for the answer
but if the inwards curve LERX is better then why J-17 and F-18 use their massive outward curve LERX? , i mean their flight is obviously after Su-27 and F-16, why they didn’t use the better solution?

Well its not definitive X is better than Y. Inwards (then typically slightly outwards) curved design is more efficient, because it matches behaviour of vortex better. Such quick outward curve creates bigger vortex, but not “forces” the generation of the vortex in a controlled way, it merely creates bigger vortex at the cost of increased drag.

If you have enough room, F-16’s or Su-27s “pointed ogive” shape is always the best. Its not only for subsonics, it applies for supersonic as well (concorde’s wings for example). However there are several other design criteria to consider as well.

For example, F-18A/D has LERX designed for its wingspan. Enlarged wings on F-18E require larger LERX, but lengthening the LERX equally would mean either a) lengthening aircraft would result in extra weight or b) lengthening the lerx alone which would shift aerodynamic center to front (maybe even causing too much instability for elevators to handle, which in return requires bigger elevators which causes more drag than gains), and making pilot completely blind to his underside. So like everything else, F-18E’s design is a trade-off of multiple factors.

JF-17? If you don’t have the distance, you are stuck with quick outward ogive to genarate a vortex with sufficent meaning. TBH, JF-17 is one of the rare aircraft I would call copy (I dont even call Tu-160 or F-15 copy), which is an attempt to put some F-16’s aerodynamics on a F-20 clone. Within such constraints overly wide but short ogive design is way to go..

Andraxxus, someone in another forum doing some estimation of F-35 performance, can you check the validity of it
( like where it wrong, right.. etc)
…………
http://www.f-16.net/forum/viewtopic.php?f=55&t=25735

Well his work seems thorough and accurate in method, I don’t share his assumptions, and accuracy of calculations. Let me put a wall of text and some data to point out his mistakes or areas I don’t agree.

F-15

F-15 doesn’t have fixed 27% MAC stability, its limited between 22-29,9% and typical CG travel during a mission is as follows;

[ATTACH=CONFIG]239179[/ATTACH]

Its reasonable for any maneuvering is required in mid mission, so I assume CG distance is at 24% MAC, and working from wing area and Mean chord length, it translates to 3,632 feet, not 4.

At landing CG detrimental, so that aircraft will not roll back to its rear end, I assume 10 degree AOA at landing, working from wikipedia 3-view drawing and moving backwards from 22% MAC gives CG to be roughly at the 2/3 of the F-15%’s airbrake. (too lazy to draw it and upload it here)

This means distance from the center of the elevators to CG is 7,63 meters or 25,03 feet.

So for X amount of lift, 0,1451X or counter-lift from elevators is required, so roughly 85% of the lift is used.

F-15 Flight manual gives stall speed at 30000 lbs exactly at 110 knots. Calculating Clmax from these gives us Clmax=1,2028 .

Incedentally, F-15’s maneuvering Clmax is given by Soviet booklet is 1,0. My calculation gave (1-0,1451)*1,2028 = 1,028; not too bad.

F-16

He explains CAT-I limiter well, but its implacions not. We are looking for maneuvering conditions, not stall, so whatever Clmax he found from CFD is irrelevant. AOA@G limitation is there for structural reasons and will change the REAL Clmax of the maneuving aircraft. For example, we know F-16’s turn rate, speed and altitude conditions is from its flight manual. F-16 Clmax for M0.4, M0.5 1,3991, 1,5687 respectively. For 9G at 10000 feet, its 1,1.

As for his CFD work; an F-16 blk50 at 36000lbs DI-0 stalls at exactly M0,2 at MIL thrust (according to flight manual). 78kN MIL thrust, 25 degree stall AOA, stall speed, altitude etc are all sufficent to calculate Clmax, which equates to 1,5827.

So F-16’s clmax is ballpark around 1.6 for stall and around 1.3 when maneuvering due to CAT-I and 1.1 at 9G ITR turns. Of course that is if we are talking about subsonic only.

F-35

“I estimate clmax of F-35 to be 1.8” No offense to the author, thats utter nonsense, and clearly not good enough.

Typical 64A204 F-16 uses tops out at clmax = ~1,1. F-16 adds to that primarily with LERX vortices and LE flaps to delay the stall and as a result achieves Clmax = ~1,6

What if an aircraft didn’t have LERX and LE flaps? Well F-15 uses very similar but thinner 64A203 airfoil. Despite wide body, and 64A006 wing roots, It barely manages to get around Clmax = 1,2

1.8?? Lets see the ONLY competitive aircraft: Su-27 has LERX, le flaps, and achieves Clmax = 1.85 with this THICK airfoil:

[ATTACH=CONFIG]239180[/ATTACH]

And remember, this airfoil more or less makes up the whole Su-27, from lerx to tail, excluding nacelles. Even area from nose to stinger is shaped as a supercritical airfoil, with nose look slightly downwards to improve lift in the “tunnel”. As for F-35, such lifting body design is not present on F-35 to any degree (its more like F-15’s body lift than Su-27 with lifting body), has no lerx to make airflow stick to wings, and my mk1 eyeball inspection tells it uses MUCH thinner wings than the profile above. (Abominal extensions below wing roots don’t count as wings)

So for F-35, Clmax = 1.4 is most reasonable assumption to me, as its right between F-15 and F-16; with # of aerodynamic features is also 0 for F-15, 1 for F-35, and 2 F-16, i just take the middle: (1,6 + 1,2) / 2. This is also ballpark similar to MiG-29 and F-18, and I assume F-35 wont have AOA limitations of F-16, which is unique to that aircraft. So;

And by that, “CL*A” of these aircraft should be as follows (I am also writing in feet so that you can compare with his)
F-15E = 608*1,2*0,85 = 620 ft2 = 57,6m2
F-16C = 302*1,3 = 423 ft2 = 36,41 m2 and 332 ft2 =30,84m2 @9G
F-35A = 460*1,4 = 644 ft2 = 59,83 m2

With these Cl*A’s known, we need weight to judge performance. Lets assume dogfight 500nm out take his range graph as accurate (I am also adding Su-27 as potential adversary, and just because I like Su-27)
F-15E = 58% fuel, = 18000kg
F-16C = 83% fuel. = 11735kg
F-35A = 57% fuel. = 18082kg
Su-27 = 40% fuel. = 20060kg (40% should make 500nm return trip)

While all can pull 9Gs, their ITR will differ by speed;
F-15E = 17,17 deg/s @ 292 m/s,
F-16C = 16,07 deg/s @ 313 m/s,
F-35A = 17,6 deg/s @ 285 m/s,
Su-27 = 20,96 deg/s @ 240 m/s (Su-27’s clmax @M0,75 = 1,51)

For STR we simply have insufficent data. Even we assume same Cd, we have to know exact Lift-drag to even make guesstimates about STR.

Lets go on with some other mistakes:

He is right about ANY payload attached to CFT limits F-15E to M1.4 but, again, his interpretion is wrong. To simplify, F-15E’s CFT has 6 stations. Two rows are simply groupped as inboard and outboard in flight manual and these do limit to M1.4.
However, F-15 carries AIM-120s on stations 3C, 4C, 6C and 7C EVEN WITH CFT INSTALLED. (those stations extrude from inside CFT, between CT-1, CT-2 and CT-3 like this:

So they are NOT CFT stations, and still subjected to general CFT limit of M2.0:

[ATTACH=CONFIG]239178[/ATTACH]

As for the rest, he is making assumptions. This is his idea, I don’t have a clue if they are correct or not.

Exactly.. Even F-16 is an overkill for that.. That is why your argument about how you utterly need 100 F-35As against IS was moot from the start.

F-16, or F-35 is meant for fighting other armies, airforces. Thats why me myself NOT mentioned ISIS, but Syria, Iran (as islamic dictatorships) and Greece, Armenia (as potentially hostile). All these guys have SAMs, radars and a few aircraft to threaten F-16’s no?

Based on the published figures. A fighter that cannot SC, needs forever to crawl through the transonic region and only achieves M1.6 for 2 odd minutes before it gulps all fuel, how is that close to an F-22 which supercruises faster than this thing even flies?

All true, but technically, all these stand true for F-15E vs F-16C too. Attach 12 mk-82s and F-16 wont go supersonic, an F-15 will go M1.7 even with CL fuel tank. Attach 4 AAMs and EFTs, F-16 wont go M1.8, an F-15 will go M2.4 with 4 AAMs and full internal fuel. When it comes to maneuvering, F-16 DO have slightly inferior maneverability than F-15 for most of the envelope.

Again, you have not said one thing that applies for F-35 vs F-22, but NOT for F-16 vs F-15.

1. You can’t get 4 F-35s for a price of 5 F-16s.
2. You cant operate 4 F-35s for a price of 5 F-16s.

The whole comparison and reasoning is invalid..

I wrote the numbers, If you disagree, wrote your own.

81 million system price not fly-away. System price, that is that price where your F-35 gets close to $200mil.

I took number from this 68,9 million in 2006, and adjusted for 2015 dollars make 81,2 million $
http://www.defense-aerospace.com/dae/articles/communiques/FighterCostFinalJuly06.pdf

even LRIP estimate of that source puts F-35 to be less expensive than Typhoon. 85million$ for full scale production of F-35 is wishful, but not unachievable.

And don’t be surprised to learn that each flight hour of the 35 costs ~3 times an hour of a Gripen C.

True, it will be somewhere between F-16 and F-15, comparable to Typhoon.

I vaguely remember that the RF-4 got few kms deep into Syrian territory and was shot down.. OK, and now what? Will you be using F-35s for recce because of that and claim you utterly need another 24?

Well, if your response to each accidental incursion is shooting it down, thats what happens; 1 MiG-23, 2 Mi-17 and 1 UAV shot down in 3 years. In any case, you are missing the point, I believe: Some regions are more hostile than the others and one would require an edge over the hostile countries. F-35 gives that edge, F-16 doesn’t.

In reality, the F-35 starts from a completely different IR signature level, in the first place. Kilonewtons mean energy, energy means it has to be converted into something.. You can’t make the energy simply disappear because you have added a sawtooth panel or a ceramic layer.

On this I agree. According to thermodynamics, Heat dissipation occurs due to inefficiency withing the engine. If engine has 100% efficiency, it would have exhaust temperature same as inlet temperature, but it isn’t.

Fuel cooling = Fuel heating-up directly increases engine efficency. Higher efficiency = less heat dissipation. Has nothing to do with nozzles getting colder.

Mixing with external air = Heat generated is there, but you are using conductive heat transfer instead of radiative. The problem is a jet engine ingest some 70-120 m3 of air each second thanks to several fan/compressor stages running at 6000++ RPM. How much air -without any forced induction- can be moved from tiny air vents? 2-3 m3 per second at best. Now this has really no affect on Full AB, it may have some use with minimal thrust cruising, due to IR radiation is proportional to T^4 (means 3% drop in exhaust temperature will drop IR signature by 11,5%).

Frankly, I don’t see how ceramics saw tooth nozzles etc would help in IR reduction. If anything, Ceramics would PREVENT cooling of exhaust, which would produce more even temperature along the nozzle at the cost of hotter exhaust.

F-35 flying at 250 m/s at full AB will produce 47,75 MW of power. Even at optimistic 40% efficiency at AB, thats 71,63 MW heat output.

With same speed and efficiency and throttle, an F-16 will have 49,1 MW, a Grippen will have 30,1 MW heat output. F-35 would need around 45% signature reduction just to match F-16, I don’t see how its possible with some vents or fuel heating.

Mirage 2000 is a relevant fighter even today. It can do 90% of missions the F-35 can, for half the cost.. The MiG-15 can’t do sh!t.

Ok, if thats the case, lets talk about MiG-21? Why should everyone buy a R-77 capable MiG-21s and be happy with it? Everything you say about F-35, still applies to F-16, when compared to MiG-21. In fact, a R-77 equipped MiG-21 can threaten an F-16C way more easily than an F-16C can threaten F-35.

Yes.. It’s way too costly because it sucks at what most air forces need ..

If an air force buys F-35, they must see the need for it. Otherwise why should they buy such an expensive aircraft, if its NOT what their airforces need? Again, same arguements could be easily made for F-16 too, which is completely unnecessary if you are only patrolling borders, and expecting nothing to fight back.

If you were in a country which happen to have 1471 km border with 2 islamic dictatorships, additional 2131 km with two more countries who openly wants half your territory for sh!tloads of “it belonged to us some hunders of years ago” nonsense, you would WANT F-35 exactly as it is, a hunded of it. Building 200 more F-16 instead would not have same deterrance value of 100 F-35s.

The F-22 would have cost a double today, but counted on the existing production run of mere 187 aircraft. If the F-35 funds were used for F-22s instead, it would have become an extremely deadly aircraft at ~$125mil. And THAT is a good deal..

Excluding operational costs, and assuming F-22 is really that better than F-35 in kinematics AND range, which I am not so optimistic about.

It can’t.. Most of all it can’t be at two places at one time..

Really? What is detect/track/attack ranges for F-16A and how is it compare to F-35? And how often you see F-16s do CAP missions alone?

And In real life, any F-16 that flies CAP along Syrian-Turkish border flies 80-140 km away from 40+ S-200 battallions is under constant threat, even when under dense ECM support. In the same jamming environment, F-35 would be a ghost to them. A hundred F-16s cannot replace a single F-35 squadron there. Expensive? No, its only the cost of winning.

Of course. As a side info, F-15C production ended in 1985 and PW-220 is introduced in 1986, I don’t know if ANY F-15C left factory with -220s, and in practice, only 2 ANG squadrons (86+1 engines) upgraded to -220E by 1996 for 542 mil $. IDK if more F-15Cs are upgraded (there was a desire to upgrade 7 squadrons in total back then, but as far as I know, 4 didn’t realized)

So going that far into details, MiG-29 was faster than most F-15Cs in 80s and 90s.

And despite obviously improved dash speed, PW-220 didn’t produce more static thrust than PW-100.

The point is, such generalisations (like T-50 looks faster than F-22) hardly give any conclusive info.

By the way, the F-15C can accommodate the -229, but USAF chose not to install them. Performance would be pretty scary.

Curiously, -220 engined F-15E can do M2.4, but -229 engined ones can only do M2.3. Though it would have improved kinematics of F-15C very much.