Operational Performace Comparison: Viper, Beagle, and Stubby

The F-35 compared with other modern jets.
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sprstdlyscottsmn

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Unread post08 May 2018, 17:48

Further update. While I do not have flight manuals for the Rafale or Typhoon, I do have similar information available for them as I have for the Su-35 (except for actual clean Cdos and a lift curve). This has gotten me thinking that maybe I should make this less US focused. I really wanted to have the AV-8B+ to show what a leap in capability the F-35B is, but in the end it is just too poor at the interception and escort aspects. So in effect I am seriously considering altering the planes in test. Potential changes are the addition of Rafale and Typhoon as well as the potential replacement of F-16C with F-16V and SHornet Blk II with Blk III (upgrades begin 2020, it's in the timeline I am looking at). Maybe Hornet C with RACR upgrade? Is that funded somewhere? I know only one person left on the boards cares about this, other than me, so I don't expect the thread to blow up with comments.
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Unread post08 May 2018, 23:50

I'd certainly be interested to see your updated analysis, so maybe that brings the number of people who care about it to two. :wink:
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Unread post08 May 2018, 23:59

Well alright then!
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Unread post09 May 2018, 00:01

I think most members here care, it's just hard to contribute, or even make meaningful comments if aerodynamics is not your field.
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Unread post09 May 2018, 03:30

sprstdlyscottsmn wrote:Further update. While I do not have flight manuals for the Rafale or Typhoon, I do have similar information available for them as I have for the Su-35 (except for actual clean Cdos and a lift curve). This has gotten me thinking that maybe I should make this less US focused. I really wanted to have the AV-8B+ to show what a leap in capability the F-35B is, but in the end it is just too poor at the interception and escort aspects. So in effect I am seriously considering altering the planes in test. Potential changes are the addition of Rafale and Typhoon as well as the potential replacement of F-16C with F-16V and SHornet Blk II with Blk III (upgrades begin 2020, it's in the timeline I am looking at). Maybe Hornet C with RACR upgrade? Is that funded somewhere? I know only one person left on the boards cares about this, other than me, so I don't expect the thread to blow up with comments.

That actually great, iam very much interested to see how these 4.5 gen compared, Rafale probably have the best STR at low-medium altitude or so i have heard.
viper12 wrote:I'd certainly be interested to see your updated analysis, so maybe that brings the number of people who care about it to two. :wink:

make it 4 :mrgreen:
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Unread post09 May 2018, 04:09

I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.
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Unread post09 May 2018, 14:57

collimatrix wrote:I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.


Ditto!

The issue for the general public is this: They've heard everything from it got whipped by an old F-16 with drop tanks to.... it's 2nd only air to air to the Raptor.

So which is it? Or is the truth somewhere in between...??
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Unread post09 May 2018, 15:09

collimatrix wrote:I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.


The F-35A is the most "empty" fighter aircraft... possibly ever. With an empty weight of 29,300 lb and a total internal load of 23,500lb (weapons and fuel) and having it's length dictated by the LHA/LHD elevators, it certainly had to make concessions.

Wave drag can be thought at a very high level as fundamentally coming from Area Rule and Fineness Ratio.

The FR is where the F-35 suffers compared to the F-22 (as a directly applicable example). They have similar body width yet the F-35 is a dozen feet shorter. Yet, despite being a dozen feet shorter with a similar body width and shorter wingspan the F-35A manages to have about 2,200lb MORE internal carriage (between fuel and weapons) because it only has a single engine to deal with.

Now, the Area Rule is how smoothly the cross section increases down the length of the plane. Look closely at the F-35A. As the peak of the canopy blends back toward the fuselage the pointed intakes begin. Once the intakes meet the center body the bumps for the A-G weapons bay begins. Once those bumps reach their peak the wing begins. Follow this thought process as you look at the side and bottom views of the F-35A and you will see that it appears to have near flawless area ruling. Look at the bottom. Why doesn't it have a flat bottom like the F-22? It would be cheaper to manufacture and make it roomier in the weapons bays right? Instead it looks like a river coursing over rocks. The lower surface is carefully sculpted.

This is why an F-35A can effortlessly exceed 1.6M if the pilot chose to ignore the limits. Evidence of this? The F-35C has been taken to 1.6M. It has the same engine. It has a much larger wing that contributes to a poorer wave drag (as evidenced by the transonic acceleration times). If the same engine can push the plane with much more wave drag to 1.6M then it can easily push the F-35A beyond that. Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)

The design priorities of the F-35 are to be the perfect plane for the actual missions the F-16 and F/A-18 do in real life. Even ignoring the stealth and systems side of it, just looking purely at payload and performance, it exceeds the capabilities of the teen-series by far.

A clean F-16 is a hotrod, but it is also useless. Send it out on a CAP mission and it sees an increase in form drag and weight from missiles, pylons, fuel tanks, and maybe ECM gear. Send it out for a strike mission and it sees a bigger increase in form drag and weight from bombs and targeting pods in addition to the missiles, pylons, fuel tanks, and ECM gear.

A clean F-35 is not quite as much of a hotrod. Send it out on a CAP mission and it sees the weight of the missiles, no form drag. Send it out on the strike mission and it sees the weight of the bombs, no form drag. No pylon drag, no fuel tank drag, no ECM drag, no targeting pod drag.

Before you even add in the VLO properties, the F-35 is one of the finest warplanes ever designed.

As to the F-16 "dogfight", I will get to that later.

*EDIT* Now it's later. The only people who believe the F-35 lost a dogfight to an F-16D with two empty gas tanks are those who only read the hit pieces and not the test pilots report on the encounter, that was attached to at least one of the hit pieces.

The test was a CLAW test of the AoA region between 20 and 25 degrees AoA. The F-35 in question was not 3F or even unrestricted 3i. What the test pilot commented can best be summed up in a few points.

1. The CLAW begins blending from low AoA logic to high AoA logic in the 20-25 degree region. This should be increased to 35 AoA as at 25 AoA the F-35 still flies as if its at low AoA.
2. At the specified test AoA, the F-35 cannot generate sufficient rate to achieve or maintain an offensive position on the F-16 target. The specified AoA also does not allow sufficient energy retention.
3. Overall control responsiveness felt sluggish, particularly in pitch and yaw. Previous flight tests on later CLAW builds (remember, test was not done using latest CLAW in test at teh time) already demonstrated the safe use of more rapid control deflections.

So to further summarize: Open up and adjust the CLAW, don't fight at 20-25 AoA.

Recall Dolby Hanche talking about how he can rake the nose hard in an F-35 to get angular position and then accelerate quickly to recover the lost energy, an acceleration he states the F-16 would have to drop it's nose to achieve.
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Unread post09 May 2018, 16:58

sprstdlyscottsmn wrote: Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)


Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs
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Unread post09 May 2018, 17:36

Ton as in 2000lbs
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Unread post09 May 2018, 18:00

zero-one wrote:Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs


Hey there zero one.

So AFAIK there is no 1,000 pound ton. There IS a 1,000kg ton (tonne, long ton, or metric ton) which is 2,200 lb.

Russian planes seem equipped only for 500kg and below weapons with the exception of the KAB 1500, a 1,500kg class weapon, and only three can be carried.

European planes only seem to carry LGBs instead of JDAMs, but even looking at "one-ton" LGBs the Tiffy carries a max of 2, the Rafale carries a max of 3, the Tornado carries a max of 2.

A Mk84 weight 2,031lb. Adding the GPS guidance kit to it will only increase the weight. It will not increase the weight beyond 2,200 lb as the GBU-10 LGB weighs in under that. So, being between 2,000 and 2,200 lb I just say "ton" as whether using metric or imperial it isn't far off.
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Unread post09 May 2018, 18:44

sprstdlyscottsmn wrote:2. At the specified test AoA, the F-35 cannot generate sufficient rate to achieve or maintain an offensive position on the F-16 target. The specified AoA also does not allow sufficient energy retention.


As a minor nit on this. The pilot in the test report directly said "The CLAW prevented such shot opportunities" -- in other words, it wasn't because of fundamental aerodynamic limitations with the F-35 aircraft, but because of the software limitations put in place at that time that it didn't have sufficient rate. One of his recommendations was, of course, to adjust the CLAW parameters to increase that rate -- so it should no longer be an issue now.
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Unread post09 May 2018, 18:54

vanshilar wrote:As a minor nit on this. The pilot in the test report directly said ...

I appreciate the quote. I don't have my copy of the report on hand.

I don't think the CLAW can change the aerodynamics though. Lift at the AoA is the lift at the AoA. What the CLAW can and does control is the transition and onset rates for pitch, roll, and yaw.
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Unread post09 May 2018, 19:21

I do not know to what extent this plays into the CLAW discussion, but I do recall the test pilot in the "infamous CLAW test" was stated as having a lot of flight time in F-15's, if memory serves, so it is possible he was "fighting" the F-35 as he would an F-15, unless the test had very specific procedures / test cards. The more I think of it, I'll stick with specific test cards, so his F-15 experience probably had little to do with the test. However, more recently, we have had quotes from F-35 pilots stating that one of the reasons the F-35 is waxing everyone's a$$ (my words) is because they have learned how to fly it -- how to take advantage of its strengths and avoid its weaknesses. So it appears quite possible that, as Spurts says above, don't fight the F-35 in the 20-25° AoA regime. Perhaps that regime is not one of the strong suites of the F-35. Either stay below 20° alpha and keep your energy up, or transition up to 35-40° (numbers I pulled out of thin air) to slow down, and out-radius the other guy.

While it appears that the LM flight control wizards were able to open CLAW up and improve those rates, it is possible that fighting the F-35 in that blended control region is not the F-35's strong suite. FWIW.
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Unread post09 May 2018, 22:39

sprstdlyscottsmn wrote:There IS a 1,000kg ton (tonne, long ton, or metric ton) which is 2,200 lb.


Just to nitpick a bit, a long ton is actually different, being the heaviest of all tons around ; it's 2,240lb = 1,016kg : https://en.wikipedia.org/wiki/Long_ton
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