garrya

It is with jettison external fuel tanks Higher sustain turn rate of F-15 could be due to high altitude or different fuel load

why do you take F-15 as an example ?? F-15 doesnot have Leading edge flap , while both F-16 and F-35 does , which mean both F-16 and F-35 can move their LEF to generate highest possible CL regardless of AoA F-15 doesnot have vortex creating device while both F-16 and F-35 ( as shown in previous page ) F-15 is positive stable while both F-16 and F-35 are negative stable which means in WVR engagement the F-15 tail is down loaded, meaning the wing and fuselage must provide additional lift, that not the case for either F-16 or F-35. F-15 CLmax is 1.2 AFAIK So why dont you compare it to something more comparable ? Take for example Su-27 which have not only vortex creating device ( LERX ) but also LEF and it is negative stable too. Now if you look at Su-27 manual At Mach 0.5 its max AoA is 24 => CL is 1.85 At Mach 0.6 its max AoA is 23 => CL is 1.7 At Mach 0.7 its max AoA is 22 => CL is 1.58 At Mach 0.8 its max AoA is 20 => CL is 1.45 On the other hand, when F-16 makes 9G turn regardless of speed , its max AoA is 15 degrees => CL is about 1 Lift = 1/2*V^2*reference wing area*air density *CL Take for example when speed is mach 0.5 ( about 164 meters/sec) => CL is 1.85 air density at sea level is about 1.2kg/m3 Su-27 wing area is about 62m2 so total amount of lift is 1.85 * 1/2 * 1.2 * 164.8^2 * 62 = 1879085N Su-27 empty weight is 16380 kg, max internal fuel is 9400 kg, Su-27 with 50% fuel will weight about 21080 kg max G it can pull based on lift generated is 1879085/9.81/21080 =about 9G that is more than 30 degree/second ITR On the other hand ,in the same condition ( sea level , mach 0.5) an F-16C with drag index =0 will have maximum instantaneous G of 7G and ITR = 24 degrees/second. More than 5 degrees/seconds different in turn rate, all from much higher CL achieved at higher AoA. Now on to the issue of AoA vs Structure integrity , even at Mach 0.7 , Su-27 can still maintain AoA of 22 degrees , and as a result it is able to achieve much higher CL than F-16, there is no reason to believe that F-35 structure is much weaker than Su-27 or even weaker at all, so more than 15 degrees AoA at dogfight speed is completely flexible. And if F-14 can still dogfight with F-16 even though its main advantage concentrated around Mach 0.55-0.6 then there is no reason why F-35 couldnt. Especially consider that F-35 has a massively powerful engine that will allow it to regain speed very quick after a hard turn and it also has impressive yaw rate of over 28 degrees/second

Dont " sigh " with me unless you have actual number or calculation to prove your point. Remember that all our discussions regarding F-35 and F-16 are based on guesstimation of F-35 dynamic thrust and CL. Neither me or you have the exact figure at the moment CAT was done to help prevent deep stall as the single rudder loses effectiveness at much higher AoA and the pitch onset rate was higher than anything ever seen before so they wanted to make sure the plane did not over rotate at high speeds. But at the same time , the AoA limit at high G also limit its maximum achievable ITR. And F-35 doesnt need much higher AoA than F-16 in this case. A slight 5 increased from 15 to 20 degrees AoA increase CL significantly. And what happened with your opinion regard dogfight speed ?? just a few pages ago you said common dogfight speed is about Mach 0.5-0.6 , now you change your stand and low speed not important ? the maximum 25.2 degrees limit is at 1 G , go to 5G and that limit decreased to 20 degrees. F-16 cant reach 30 degrees AoA without stalling

Remember though , this is with 7G limit in place

No , F-16 hold advantage in STR but not ITR It not just nose pointing like in case of TVC (in case of F-35 the direction of travel also changed , not just the direction of the nose ), F-35 capable of generates higher CL because it is controllable at higher AoA than F-16 , F-16 max AoA , especially at high G is limited by the CAT limiter , this in turn reduce its CLmax At 9G , even with CAT I limiter the maximum AoA is only 15 degrees However, CL max of F-16 dont stop until AoA of about 35 degrees, even between 15 and 20 degree , the CL different is very significant. At high G turn , F-16 ITR is limited by its AoA rather CLmax of the airframe For F-35 since its controlable AoA is higher , its CLmax at high G will also be higher , thus it will be able to generate higher lift and as a result higher ITR (there is nothing unconventional about this ITR , it the same case for all aircraft without an AoA limiter and controllable at high AoA). Disadvantage is obviously bigger drag , but as stated F-35 regain speed even better than F-16 due to its engine in which case F-35 can break AoA or dive to regain speed, with its enormous thrust that would be quick , like the pilot said F-35 can regain speed as quick as F-16 in a dive

Well , higher AoA turn will generate more drag , no doubt. But i disagree that it is just nose pointing ( as in post stall maneuver). F-35 has max CL at AoA higher than max allowable AoA of F-16 so while it generate more drag , it also generate more lift.As an anecdote, during the infamous "dogfight test" the pilot talked about flying in the "blended region" (for the FBW software to know where to go from traditional control to high AoA control schemes) at 20-26 degrees. He mentions that as 26 degrees the aircraft is actually still "shallow" and would be able to roll well (still a lift margin on the wing) and that the beginning of the "blended region" should be pushed up to 30 degrees or greater from 20. Of course as mentioned earlier , a high drag turn such as one performed by F-35 at high AoA will deplete aircraft of speed very quick, but it is also noted by the Norwegian pilots that f-35 recovered speed rapidly compare to F-16 (at dogfight speed , obviously). https://theaviationist.com/2016/03/01/heres-what-ive-learned-so-far-dogfighting-in-the-f-35-a-jsf-pilot-first-hand-account/ Now before you question the pilot opinion and said " how can F-35 has better acceleration than F-16 if it has lower T/W , and more draggy airframe " i already ask that question for you and here is the answer:

We started this whole discussion about body lift and what not because on page 339 , i questioned your assessment regarding F-35 CL and ITR. Then now when we got reply from John , you changed your mind and said that is what we know at the start ????? His first answer also made very important point regarding lift and AoA " relationship between lift and AoA is non linear, and it is also nonlinear vs Mach number, so there is no way to extrapolate AoA at low speed to IRT at combat speed" Then again , why would it be limited to slow speed only ? what if F-35 AoA at high speed ( mach 0.7-0. 8) is higher than F-16 also. Ultimately , like i stated at start we dont know its max CL so you cant conclude that its ITR is bad Firstly , the whole body , not just that specific part will generate lift at positive AoA (AFAIK , aircraft made high G turn at positive AoA ) Secondly , if that was what you mean then why didnt you said it the first time i brought up tube body ? why mention it just now when we got reply from John ? And now you have to prove that small area next to F-16 wing and its body will generate more lift than the whole underside of F-35 it may be more efficient per square inchs (by how much we dont know). But large part of F-35 is its fuselage And how am i wrong exactly ?, as shown negative stable aircraft dont all have same amount of "negative" ( their relative location between CoL and CG isn't all the same ) Why do i focused on the whole body and LERX ? because the whole flat underside of F35 will also generate lift. And not long ago , we had a similar discussion in this thread , you also said F-18 has better body lift because its underside is less boxy than F-35.So obviously i would assume you talked about the entired fusalage You just keep shifting goal post Because it contribute significantly to body lift at AoA Does that ITR line appear in the EM graph or not ? No. So basically you draw a curve outside it. You can argue that the curve is valid because that is ITR that pilots will achieve when he excess the recommended G limit. No problem, but if that what we do then we should do that to all aircraft in comparison , not just F-14. Why should we limited ITR of F-35A to 9 G and F-35C to 7.5G if it has been tested to 9.9G then ? , why should we limited F-15 ITR to 9 G if it has excess 12G before in combat ..etc so and so on. Either we use the recomemded limit or we dont , there no middle ground. That not what you posted the first time you said he is wrong .Here is what you posted in case you forgot : Unless you made some calculation to show ,Iam not so sure about that , F-16 late and early version are a few thoundsands pounds different and that translate to quite different performance. I dont believe that changing fuel load wont changing kinematic performance dramatically And? your point is ?

Anyway regarding the issue of body lift and AoA. I took the question to Johnwill. To anyone here who not familiar , he is one of those engineers in F-16 program. Here is his answer tube vs boxy design and body lift

Now we are just arguing circle really. well the lead aircraft is piston and they are at sea level so they wouldnt be moving so fast. And like you said P-51 have higher top and cruise speed than Spitfire. So you can distinguish the AoA different between F-35 and F-22 but not the AoA different between F-22 and F-16 ??? Iam not quite sure what you are going with this , so assuming F-35 wing produce more lift per area than F-22 wing ? and ??? their sweep angle is not even the same to begin with Not all negative stable aircraft have the same amount of negative stability , even between F-16 version there is different in stability The part that joined the fuselage and the wing is LERX , hence they are called leading-edge extension This is new , the first time i heard that F-16 body can generate lift at 0 AoA , can you give the source for that ?. AFAIK , F-16 only start to generate body lift at positive AoA ( same for F-35 ) I understand it fine , you still haven't been able to reference the source for " boxy fuselage design generate less body lift than tube design " Yes that the point of LERX , F-35 doesnt have LERX but it has it own way to generate vortex too In which case i dont see how F-16 can be considered better So basically his number is correct Which the same case go for F-15 , F-35 , F-4 , Rafale ..etc basically all aircraft because their ultimate G limited must be higher than recomended G limit by a certain factor. But we dont draw a new ITR curve for all those do we ?. Either we treated all aircraft as able to excess their recommended G limit or we used the recommended G limit value in manual for all of them Did you not paid attention to the discussion ? he have to calculated those value because flight manual only give performance value when internal fuel load is a general percentage such as 50-100% , it wont give turn rate value when fuel load is at 28% or 73% or 46% or any similar value. The problem with a general value like 50 or 100% percentage is that they dont show the whole picture. If you have F-16 , F-15 , F-18 , F-35 , F-14 . All loaded with 50% internal fuel , their maximum afterburning time and combat radius would be very different. Hence the reason for him to equalize their fuel load based on same mission requirement. And you still haven't shown exactly where is his mistakes . First you written value for 10K feet and Mach 0.4-0.7 while his chart is at 20K feet , mach 0.8. Then you said he wrong because ITR at 20K feet is the same as value in 25K feet chart. But then a closer look shown that ITR at 10K feet is also a similar value because it is structure limited at lower altitude.

I dont see how i proving your point given that F-22 have slightly higher AoA than F-16 in the video So now you just disproved your own argument Basically ,from the video ,when a F-16 with 2 EFT and F-35 follow a slow spitfire, they both have smaller AoA than F-22 and F-35 follow a fast P-51 So how your lift loading and AoA theory fit in here ???? F-16 with 2 EFT has less lift loading than a clean F-22 ?? doesnt make sense vapor trail form due to vortex and those vortex reduce lift AFAIK , anyway , it doesnot make sense if we combined the 2 video ( as stated above) well negative stability = centre of gravity behind centre of lift. If i recall correctly centre of lift move to the rear as aircraft flying faster , so negative stability would mean your nose will tend to pitch up more when you about to stall F-16 benefit alot from body lift due to the LERX , it create vortex at AoA.Again that has nothing to do with boxy vs tube body. You still havenot cite the source for " boxy body mean less body lift compared to conventional one '' Actually, now that i paid attention to it , ITR of F-14 at 10K feet , Mach 0.8 is 14 degrees/second. So if i took your word for it then that mean F-14 ITR between 10-25k feet is limited due to structure limit ( or alternatively it could be structure limited at 10k feet and lift limited at 20-25k feet ). Regardless , i dont see how the different is so big that it cant be due to fuel load I fail to see how they missed the mark here, you said the different is too big for the fuel theory to hold water , but still havent made any calculation to show otherwise????

F-22 doesnt have better wing loading than F-15 , it has more boxy fuselage and also lack variable intake I would really need a source for this " basic aerodynamic " you talking about. I dont see the wing shaped F-16 or F-15 body any more than it does to F-35. If the subject is something like B-2 then fair enough but i just dont see it the case for tube body The point of variable intake is to create shock wave thus recover pressure for engine at high speed , this is the first time anyone tell me variable intake is for better dogfighting capabilities

In link below F-22 has higher AoA than F-16 ( most noticeable around 0:16) In link below F-35 and F-22 both have comparable AoA and both higher than AoA of spitfire ( very noticeable around 2:19) About their respective AoA , that could be the result of negative stability too, tail may not generate enough lift to counter the CG too far backward Compared their respective wingloading , F-22 should have lower AoA. But from video it clearly have higher AoA And the charts also have the speed that aircraft achieved their respective sustained turn rate. I already said i dont have the 20K chart , if you said he is wrong shouldnt you post the chart to prove your point ???

And why would a boxy shape mean less body lift ? F-22 looks boxy too. Compared to F-15 , F-35 has negative stability which means its tail can contribute to lift too. Actually , i have never heard that variable intake will increase lift in dogfight.

I guess you are referring to this picture There is 2 problems with getting assumption from that photos 1- Does the F-35 flying at high AoA or is it start to pitch up ? like in this picture F-22 appeared like it has higher lift loading too 2- How much fuel do those aircraft carry ? if they carry same percentage of fuel ( assuming near 100% ) then it clearly put F-35 in a disadvantaged position because an F-35 carry alot more fuel internally than F-16 (it has almost twice the combat radius ). If you equalized their combat radius aka fueled them according to mission requirement , then that a different question all together. Will an F-16 with 2 EFTs has better lift loading than F-35 ? unlikely Moreover , the different between their AoA is exaggerated alot due to the angle the photo was taken So by straight out turn fight , you mean only turning in horizontal circle ? In what case dogfight even limited to that only ?, so pilot suddenly dont use what they learn from Boyd energy maneuverability theory ??? I havent seen the chart for F-14D at 20k feet , however , you should consider the fact that , all flight manual only ever show turning performance when internal fuel load is 50% or 100%, while in his analysis , he actually calculated how much fuel percentage they need to carry , how much do they have left at dogfight point. Since their fuel load and fuel consumption is completely different .So that explain the different between figures in his analysis and in EM chart. You could simply copy and paste EM chart directly from flight manual but that would missed the point completely

what visual cue and figure that you talking about here ? we dont even know F-35 CL to begin with The only graph for F-18 that i can find is this one and may be in that same configuration F-16 only has 1 degree/second better than F-18 (i havent bothered to check it , so i will take your words for it), but nothing to conclude that an F-16 with no EFTs dont have much better STR than F-18 especially considered that a small aircraft like F-16 will be affected by heavy load more. Then nothing certain to conclude that F-35 dont have good ITR either , pilot who flied it clearly rated it very good in ITR department. You keep insisting that pilot of F-16 , F-15 will let their air speed decay down to Mach 0.6 when dogfight with F-14 , instead of using aircraft to their strength ( high speed turn ) Enlighten me where is he wrong again ? his chart literally showed turn performance at Mach 0.8 , 20.000 feet . You put up some number showed turn performance of those aircraft up until Mach 0.75 and 10.000 feet , then you concluded his number is wrong because they are not the same as your?????? what kind of logic is that ???? Then you also ignored the fact that he dont use the same 50% fuel load for all aircraft ( because their internal fuel isnot the same ), instead he measure the specific amount of fuel they will need to carry based on fuel flow chart and using same mission profile.

And this based on what????? energy management has been an important part of dogfight since WW II, there are ways for fighters to regain speed such as low yo-yo , or defensive spiral,.. etc.And if the pilots using sustained turn instead of ITR , he wont lose air speed either. It no longer like in WW I where 2 aircraft keep turning in flat circle and losing air speed

And neither of them has the same 9 G ultimate limit as F-16 or F-35A The same can be said about F-15 , F-4 , Mig-25 ..etc all of which excess the advised G limit in service , but we dont draw a new ITR for them sustain combat may be no , but if he's in a pinch then i dont see why they cant use it to escape or get in opponent's tail I would have to call BS on that. Pilots will always use aircraft to its strength rather than the opponent strength ( hypothetically ,if an F-16 has to dogfight with a Spitfire, the pilot not gonna do the slow turning fight ) . And there is no point designing the F-16 that perform best at Mach 0.85 if dogfight only happened at Mach 0.5 , it not like F-16 need to be an interceptor or anything. modern aircraft such as the Rafale have an over G switch where pilot can turn off the G limiter so that he could excess the G limit , the question is whether F-35 has one or not.And that doesnot seem like a complex thing to make (Actually come to think of it, F-35 has been tested to 9.9 G, so obviously either its limiter is not stopping at 9 G or it can be switched off) yes , i did said F-14 has smaller turning radius And he has more available speed to trade for altitude or ITR. Then bigger T/W will give him easier time regain the losing speed in a turn too Hypothetically speaking , a piston fighters from WW II have very good turn rate at slow speed , that doesnt mean they are superior in dogfight combat to modern jet As demonstrated in flight manual ,Its sustained turn rate isnt superior to all, and it achieves the max turn rate at lower speed along with a lower T/W , which means inferior vertical fight performance. Then twin engine often lesser roll rate too. what ?????? , iam not the one who draw ITR outside the chart , and all information i just posted can be see clearly on the graph too I never said F-35 would depending on turning to survive , in fact i believe that turning is of lenser importance after the introduction of HOBS missiles

Which is not demonstrated in manual .You can argue that there are case where F-14 did turn over the maximum G limit stated in the manual. But an exception shouldnt be treated as the rule , and F-14 is not the only aircraft where pilot demonstrated higher G turn than stated in manual . F-15 did that before , so is Mig-25 , so is F-4 ,..etc and nothing to say that F-35C and B wont be able to turn more than the limited 7.5 G either. In fact one can say that if F-16 didnt have the limited , it can easily go over 9 G too , who know how many G those aircraft can take until the airframe break apart ? if we give F-14D the benefit of the doubt that it can go over the G limit , then why shouldnt we give the same benefit of the doubt to F-35A/B/C , F-15 ..etc ? From the manual when dogfight happened at 10k feet : F-15 max sustained turn rate is 14 degrees/ second when speed is around Mach 0.85 F-14 max sustained turn rate is 14.1 degrees/second when speed is around Mach 0.65 F-16 max sustained turn rate at 10k feet is 14.25 degrees/second when speed is around Mach 0.85 Basically in term of sustain turn rate F-16 is on the lead with 14.25 degrees/sec followed by F-14D at around 14.1 degrees/sec , then followed by F-15C at 14 degrees/second . Different in sustained turn rate is slight . However ,the different at speed where they achieved their sustained turn rate is big , both F-15 and F-16 achieve that around Mach 0.85 while F-14 achieved that around Mach 0.65. So basically F-14 will have smaller turn radius , but F-15 , F-16 both have more excess speed to go vertical( they also enjoy advatage in T/W if i recall correctly ). Even in WW II vertical fight is important part of BFM combat. And ofcourse one notable advatage that single engine fighter will enjoy is roll rate To sum up i dont see why F-14D should be considered better (aka the best) in dogfight than F-15 , F-16 or F-35 No it isn't , the chart show sustained turn rate at Mach 0.8 , 10K feet while you only listed number until Mach 0.75 which is not where F-15 and F-16 start to shine , another thing is that he put all aircraft in the same mission profile (equal combat radius and afterburner time) instead of equalize fuel percentage Yes i would , simply not satisfy with your explaination

In what way? F-35A have very good ITR ( comparable to both F-15 and F-22) , and mediocre STR ( which still better than F-14D anyway) F-35C have good STR, and mediocre ITR (which is still better than F-16) Performance of F-35B is limited but it not like Harrier was extremely maneuverable or anything I dont buy this, unless we talk about turning as strictly ITR and ignored the structure G limits of it.

There is an analysis made by an aerodynamic engineer about dogfight capabilities of F-35 and various others US platform in the link below, same combat missions are used in the comparison ( Most of his data is from flight manual) http://www.f-16.net/forum/viewtopic.php?f=55&t=25735&start=285 Draw your own conclusions

thank alot for the contribution man :D , i will add information to the post about RWR later ( just a bit busy at the moment that why i haven't public new post :P )

Thanks you for your constructive criticism, i will look into it:P

It was written by me, thanks alot for helping me advertise it though, i really appreciate that

So as i understand the 32Mbyte/sec is the peak speed ? or average speed ? :huh:. Seem like most people have slower internet connection according to this https://en.wikipedia.org/wiki/List_of_countries_by_Internet_connection_speeds Btw do you like the new or old display more ? :P

:D thanks you man, btw, i just tweak the display of the website a little bit, change some pictures to gif hopefully it looks abit better, but iam not sure whether the website will take too long to load ( it load fine on my laptop but i have very quick internet connection). So if you don't mind can you try and tell me whether the blog load too slow or not?