F-35 air-to-air - Pro and Con

Discuss the F-35 Lightning II
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smsgtmac

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Unread post21 Jan 2014, 02:35

zero-one wrote:Salute Mr Gums.

So what do you think about all this "F-35 accelerates slower, turns a tad bit wider" at a certain speed, load out and altitude talk,

is it really a bit of over reacting to some test done on an End-of-life airframe in a worst case scenario, or are you a bit worried over the performance of whats intended to replace our beloved Viper.

Just want to know what you think.


Cheers :mrgreen:


I just want to know where the quote "F-35 accelerates slower, turns a tad bit wider" came from?
BTW, EVERY airplane has those 'features' at a certain speed, load out and altitude". The secret is to get the other guy to fight where it affects him more than it affects you.
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Unread post21 Jan 2014, 03:15

Salute!

Sgtmac has the right question.

Way it looks, the F-35 corner velocity is actually a bit slower than the Viper. So do the math on turn radius at 350 knots or a bit slower.

Accel looks fine to me, unless you are st and level and try to get supersonic. Viper was same way. Hell, just unload a bit and zip right thru the mach. BFD.

Let's face it. The Subby ain't no Raptor. It will have a decent A2A capability, even in a knife fight. On the strike missions, it will beat anything out there friend or foe.

Gums....
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Unread post21 Jan 2014, 04:32

smsgtmac wrote:
zero-one wrote:Salute Mr Gums.

So what do you think about all this "F-35 accelerates slower, turns a tad bit wider" at a certain speed, load out and altitude talk,

is it really a bit of over reacting to some test done on an End-of-life airframe in a worst case scenario, or are you a bit worried over the performance of whats intended to replace our beloved Viper.

Just want to know what you think.


Cheers :mrgreen:



Ditto

I just want to know where the quote "F-35 accelerates slower, turns a tad bit wider" came from?
BTW, EVERY airplane has those 'features' at a certain speed, load out and altitude". The secret is to get the other guy to fight where it affects him more than it affects you.
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Unread post21 Jan 2014, 14:52

The "F-35 accelerates slower, turns a tad bit wider" statement came from the 2012 evaluation review that made headlines all over last year.

The one that said that baseline performance specs were relaxed for all F-35 variants, (5.3Gs-4.6Gs, etc etc.)

On one hand, those specs may have been taken from an overloaded, very slow moving F-35

but on the other hand(which most critics like to use)

that may have been a best case scenario, A-A configured, corner speed test on the F-35 and it bearly reached 5Gs.
and transonic acceleration was 8 Sec slower than a loaded F-16 block 50

the truth may be somwhere in between.

This is why I started to look at some figures between the Viper and the Stubby

F-35A

Weights
Empty: 29,300
Fuel: 7,200 (40%)

Weapons: 1,932 lbs
4 x Aim 120C missiles: 1,340 lbs
2 x Aim 9X missiles: 376 lbs
180 rounds: (dont know the weight, estimate 216 lbs [1.2lbs per round])
Combat weight: 38,432
Thrust
Dry: 28,000
AB: 43,000

TW Ratio
Dry:0.72
AB: 1.12
Wing Loading:83.5 lbs/ sq ft.

____________________________________________________________

F-16C

Weights
Empty: 18,900
Fuel: 4,000 (70%)
Weapons: 2,329 lbs
4 x Aim 120C missiles: 1,340 lbs
2 x Aim 9X missiles: 376 lbs
511 rounds: (dont know the weight, estimate 613 lbs [1.2lbs per round])

combat weight: 25,229

Thrust
Dry: 17,155
AB: 28,600

TW Ratio
Dry:0.67
AB: 1.13
Wing Loading: 84lbs/ sq ft.

This was a bit surprising to me, I was not intending for it to be so similar.

I realize that I dont have all the variables like Drag coeficient, Vortex lifting properties etc etc, but at least this solidified what test pilots have been saying all along that the F-35 has F-16 like performance.

This is the best that I can come up with given the info I have
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Unread post21 Jan 2014, 21:59

zero-one wrote:The "F-35 accelerates slower, turns a tad bit wider" statement came from the 2012 evaluation review that made headlines all over last year.

The one that said that baseline performance specs were relaxed for all F-35 variants, (5.3Gs-4.6Gs, etc etc.)

On one hand, those specs may have been taken from an overloaded, very slow moving F-35

but on the other hand(which most critics like to use)

that may have been a best case scenario, A-A configured, corner speed test on the F-35 and it bearly reached 5Gs.
and transonic acceleration was 8 Sec slower than a loaded F-16 block 50

the truth may be somwhere in between.

This is why I started to look at some figures between the Viper and the Stubby


The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything). The reality is that the aircraft with that load carries 4500lbs of internal combat load, at an inefficient altitude, with engines that are 20+ years old. Most modern aircraft, save for the F-15E would have severe difficulty actually achieving anything close to that.

Acceleration was not 8 second lower than an loaded F-16 Blk 50, it was for an unloaded Blk 50 (I believe putting amraam on the wingtips improves its acceleration or has no effect).

Will the F-35 have the best aerodynamic dogfighter performance? No, but air to air combat has evolved dramatically in the past 20 years, and it might have the greatest advantage over any other fighter. Our microprocessor technology has probably advanced more than any other major technology field during that period (with the possible exception of biotech.) Avionics reliability and sensor sensitivity is several generations of where we were in 1990, which means PK will be dramatically higher on current generations of missiles than before.

That necessitates changes to doctrine and capability. See and shoot first plays a far greater role into deciding who wins than before. This plays into the biggest military culture shift, the C4ISR revolution.

I'm not saying that the F-35 will be a terrible maneuvering aircraft. I think it will be solidly average... around that of most of its competitors. However it will likely be the most deadly aircraft in a battle due to its other systems which no other aircraft has.
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Unread post21 Jan 2014, 22:10

zero-one wrote:The "F-35 accelerates slower, turns a tad bit wider" statement came from the 2012 evaluation review that made headlines all over last year.

The one that said that baseline performance specs were relaxed for all F-35 variants, (5.3Gs-4.6Gs, etc etc.)

Oh, ok. I was hoping you were using a direct quote I could add to an old post. What you are finding out, is that you have enough information to think about the question, but not enough to answer it. Too bad the 'Critics' aren't respectable enough to admit that also means they don't have enough information to make valid criticisms as well. I'm on my phone now, but will post link later where I went through everything you are going though. Based on what you've done already you can probably skip a lot of it.
----------------
As promised, here are the links.
The 'Sustained G spec change' series starts here:
http://elementsofpower.blogspot.com/201 ... -spec.html

And for perspective on the (lower) relevance of the sustained g metric in a modern combat engagement here:
http://elementsofpower.blogspot.com/201 ... ility.html

There's not enough data in hand for quantifying a WAG for comparing acceleration through Mach. I expect we will have to have combat-configured F-35s spanking combat configured F-18s, F-16s, and Eurocanards in the hands of the users for the naysayers to shut up already.
Last edited by smsgtmac on 22 Jan 2014, 03:48, edited 1 time in total.
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Unread post22 Jan 2014, 00:49

hb_pencil wrote:The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything).


I've been trying to find an official reference to the above, would you happen to have a good link?
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Unread post22 Jan 2014, 01:11

cantaz wrote:
hb_pencil wrote:The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything).


I've been trying to find an official reference to the above, would you happen to have a good link?


No I don't, sorry. Its just what's been told to me.
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Unread post22 Jan 2014, 05:13

cantaz wrote:
hb_pencil wrote:The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything).


I've been trying to find an official reference to the above, would you happen to have a good link?


Do you mean 'official' as in program document? Or do you mean some authority (LM or Government) quoted as stating it so?
I ask, because when this has been brought up elsewhere, and an LM official is quoted in a reputable publication as saying the performance is measured using a degraded end-of-life engine assumption, some h8er or another inevitably jumps up and points out that how LM measures it isn't the same as the spec. I keep waiting for a bright bulb to pop up and ask:
"Well if that is how LM is measuring performance metrics against the specs to get the 'grade', then what is their point?"

This is just another issue that won't fade until more data is available. Of course by then the h8ers will have moved on to a different 'issue', hopefully on another program.
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Unread post22 Jan 2014, 07:14

smsgtmac wrote:
cantaz wrote:
hb_pencil wrote:The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything).


I've been trying to find an official reference to the above, would you happen to have a good link?


Do you mean 'official' as in program document? Or do you mean some authority (LM or Government) quoted as stating it so?
I ask, because when this has been brought up elsewhere, and an LM official is quoted in a reputable publication as saying the performance is measured using a degraded end-of-life engine assumption, some h8er or another inevitably jumps up and points out that how LM measures it isn't the same as the spec. I keep waiting for a bright bulb to pop up and ask:
"Well if that is how LM is measuring performance metrics against the specs to get the 'grade', then what is their point?"

This is just another issue that won't fade until more data is available. Of course by then the h8ers will have moved on to a different 'issue', hopefully on another program.


Okay, let me rephrase. My information isn't from LM, its from a more "credible" source with a perspective on these issues. Whether or not that's sufficient for others isn't really my concern, I just know that's how its measured in the KPPs.
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Unread post22 Jan 2014, 08:04

Perhaps not wot youse are looking for but anyway.... From Australian Federal Parliament Transcript....

PARLIAMENTARY JOINT COMMITTEE ON FOREIGN AFFAIRS, DEFENCE AND TRADE 20 MARCH 2012
“...Senator FAWCETT: I have one last question, if I can. Speaking of the key performance indicators, obviously for the overall program they are cost, schedule and performance. In cost and schedule we have seen a number of changes and rebaselining to allow for things that have happened. In terms of the KPIs against your original ops requirement document — you do not have to disclose which ones have not been met — but at this point in time have all of the original essential requirements from the ORD been met?
Mr Burbage: We have 16 key performance parameters on this airplane. Half are logistics and sustainment-related, half are aeroperformance-related and one or two are in classified areas. We have an oversight body called the Joint Requirements Oversight Council, the JROC, that looks at those requirements every year and makes decisions on them — 'Are we going to meet them, are we not going to meet them? If we are not going to meet them, what is the impact of that?' We have one this year which was the range of the Air Force airplane which had a specific set of ground rules associated with how that range is calculated which is not similar to either of the other two airplanes. The airplane flies a large part of its mission at a non-optimised altitude in the original calculation. The JROC agreed to change the ground rules to fly that airplane as the other two were flown and, when that happened, the airplane had excess margin to the range requirement. For any performance-related requirements, we artificially penalise the engine by five per cent fuel flow and two per cent thrust. Those margins are given back as we mature the design and get more and more solid on exactly what it is going to do. They are there for conservative estimation up front. We have not taken back any of those margins yet so, when those margins are taken back, the airplane will continue to be well in excess of its basic requirement. The airplane is meeting all of the other requirements today.

Senator FAWCETT: So have those requirements like schedule & cost been rebaselined, or are they are still the original ORD?
Mr Burbage: Schedule and cost are not KPPs. I thought you were talking about performance.

Senator FAWCETT: No, I recognise that. You have rebaselined schedule and cost as you have gone along. What I am asking is have the KPIs been rebaselined & does the statement you just made apply to today's KPIs or does it also apply to the original ones?
Mr Burbage: To the original set. Today, all the KPPs are green because that ground rule was changed to be common across all three airplanes on the range. But we have not taken back the margins that are being withheld to make sure those performance predictions are conservative. We are not going to have degraded engines. We basically measure our performance characteristics with a highly-degraded engine capability. Our actual flight test information coming back from the engine is better than nominal. These calculations are not done using actual airplane test data. They are done using an artificial penalty that gets paid back as the design matures....”

http://www.aph.gov.au/Parliamentary_Bus ... arings.htm
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Unread post22 Jan 2014, 08:15

cantaz wrote:
hb_pencil wrote:The reality is that most figures quote statistics with F-35 in its worst possible cases. The USG testing approach uses end of life engine performance, often with a heavy internal load: clearly the fighter isn't going to perform well. One area is the range: most people love quoting that the F-35 has approximately 590 nm combat radius (which is insufficient to do anything).


I've been trying to find an official reference to the above, would you happen to have a good link?


The most official information about this can be found here (Parliament of Australia official document from Parliamentary Joint Committee on Foreign Affairs, Defence and Trade meeting): http://parlinfo.aph.gov.au/parlInfo/search/display/display.w3p;query=Id%3A%22committees%2Fcommjnt%2F3cb4e326-70e4-4abd-acb7-609a16072b70%2F0001%22

Mr Burbage : We have 16 key performance parameters on this airplane. Half are logistics and sustainment-related, half are aeroperformance-related and one or two are in classified areas. We have an oversight body called the Joint Requirements Oversight Council, the JROC, that looks at those requirements every year and makes decisions on them—'Are we going to meet them, are we not going to meet them? If we are not going to meet them, what is the impact of that?' We have one this year which was the range of the Air Force airplane which had a specific set of ground rules associated with how that range is calculated which is not similar to either of the other two airplanes. The airplane flies a large part of its mission at a non-optimised altitude in the original calculation. The JROC agreed to change the ground rules to fly that airplane as the other two were flown and, when that happened, the airplane had excess margin to the range requirement. [b]For any performance-related requirements, we artificially penalise the engine by five per cent fuel flow and two per cent thrust. [/b]Those margins are given back as we mature the design and get more and more solid on exactly what it is going to do. They are there for conservative estimation up front. We have not taken back any of those margins yet so, when those margins are taken back, the airplane will continue to be well in excess of its basic requirement. The airplane is meeting all of the other requirements today.


So it seems like all performance-related calculations have rather serious artificial penalties. That 590 or so nautical mile combat radius originally calculated was changed to over 600 nm radius simply by using more optimized flight profile. In real life with real engines with normal performance, I'd expect the range to be a whole lot better, probably closer to 700 nm. Those artificial penalties should also affect acceleration and sustained turn rate figures. How much, I don't know but even that 2 percent is almost 1000 pounds of thrust and that should be noticeable.
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Unread post22 Jan 2014, 08:18

Damn it, spazsinbad beat me to it...
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Unread post22 Jan 2014, 12:53

I consider LM plenty authoritative on this subject.

Are the 5% fuel flow and 2% thrust penalty the totality of the end of life engine penalty, or is there more to it? Is the 5% fuel flow penalty strictly a fuel consumption penalty (range penalty), or is it more complicated than that?
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Unread post22 Jan 2014, 13:02

'hornetfinn' you have a better direct link to the material. For the life of me I could not find the several links in this very forum to the same material - could not remember the name of the senator (Fawcett). Anyhow once that is remembered the links to the dripping faucet are easy to find here: :doh:

viewtopic.php?f=22&t=22088&p=255248&hilit=Fawcett#p255248

I think we will all find that there is now too much of the same / similar info on this forum - on the internet - in the universe (I had to go there!). :D Remembering all this stuff; and remembering how to search on a vital name, can be a chore these days. Or - I'm getting old.
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