Forum: General F-35 Forum

Last edited by r2d2 on Apr 01, 2012 - 06:38 PM; edited 2 times in total

river_otter, very informative for me, thanks.

But If we think the other way around; In case that you want a supercritical wing you need trapezoid planform for strength (may be???). I mean putting the emphasis on supercritical airfoil rather than trapezoid planform.

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Quote:

I posted this article in these forums more than a year ago IIRC and thought it provides some real-world insight into the discussion, the interviewee being an ex-Hornet/Eagle Driver.

http://www.sldinfo.com/shaping-the-f-35 ... nterprise/

So after running through a gauntlet of BVR missiles in an attempt to close with it's stealthy opponent, Red will have to contend with the F-35 enclosed in it's 360-deg SA bubble, completely aware of all threats and enjoying the first shot/kill advantage. A F-35 that may not even need to engage in a low-speed maneuving fight to gain advantage as it can just shoot the approaching bad guy in the face or just as easily lob a LOAL missile over it's shoulder as Red passes by. Looks like Red just jumped from the frying pan into the fire.

Yeah. But again, this is for now, only Manufactors capabilities advertizment. And like in the history books, they do not live up the level of claimed capability.
This are not only from LM, but all other manufactors as well. Sukhoi too.

Do not take all those manufactors claims as the holy grail.. you might get disepointed in a few year..

Ok, this will be my last post on this slightly OT subject for Haavarla. AFM January 2002, Page 56 to 60 by Mark Nixon, titled Gallant Knights. There is no way on earth I am going to type the whole lot out but it does say

"The Vitezovi are the RV i PVO's premier squadron. The pilots are some of the most senior in the RV i PVO; a high number of pilots with the rank of Major (sqaudron leader) make the chain of command rather difficult for the western analyst to comprehend."

So, from this we can see very clearly that these pilots were NOT amateurs by any standard! I rest my case.

haavarla wrote:

Quote:

I posted this article in these forums more than a year ago IIRC and thought it provides some real-world insight into the discussion, the interviewee being an ex-Hornet/Eagle Driver.

http://www.sldinfo.com/shaping-the-f-35 ... nterprise/

So after running through a gauntlet of BVR missiles in an attempt to close with it's stealthy opponent, Red will have to contend with the F-35 enclosed in it's 360-deg SA bubble, completely aware of all threats and enjoying the first shot/kill advantage. A F-35 that may not even need to engage in a low-speed maneuving fight to gain advantage as it can just shoot the approaching bad guy in the face or just as easily lob a LOAL missile over it's shoulder as Red passes by. Looks like Red just jumped from the frying pan into the fire.

Yeah. But again, this is for now, only Manufactors capabilities advertizment. And like in the history books, they do not live up the level of claimed capability.
This are not only from LM, but all other manufactors as well. Sukhoi too.

Do not take all those manufactors claims as the holy grail.. you might get disepointed in a few year..

The F-35's mission systems are actually flying today so they are most definitely not manufacturer's glossy brochureware. The feedback out of the SDD program in numerous testimonies provided to Congress and, most recently to the Australian legislators, is unformly positive. Most importantly, from a credibility standpoint, there is plenty of very positive feedback from field exercises ( a couple of Northern Edge exercises, Bold Alligator 2012) playing out real world threat scenarios. Considering that they are probably the most complex aspect of the aircraft, this is remarkable. The critics don't seem to have much comment when it comes to the mission systems.

We can expect to get more feedback during the IOT&E Phase when line pilots get to wring out the jets and put them thru their paces but things are progressing quite nicely indeed

Last edited by haavarla on Apr 01, 2012 - 02:39 PM; edited 1 time in total

Some material from the Book 'F-15 Engaged'.

Autor: STEVE DAVIES & DOUG DILDY
Steve Davies has written five books on F-15.
He is a full-time freelancer aviation photojournalist, and is widely recognized as a leading expert on modern military matters.

Doug Dildy is a retired USAF colonel who spent nine years of his 26 year career in Western Europe and retired with 3.200 hours flying fast jets, almost half of that as an F-15 pilot.

As Commander of the 32nd Fighter Sq, Soesterberg AB, NL, he enforced the No-fly Zone over Iraq, and acuiring over 100 hours of combat time in the F-15.

This info is for credibility purpose as i'm sick and tired of beeing treated badly by some childish posters in this forum.
I will write down several reports from F-15 engagment, but i will not post 10+ pages, so i will narrow it down.

And i will use Word and copy past it in this thread if it is approved by moderators.

Edit: On second thought, i will post it in a new thread on general Aviation thread..
Stay tuned.

hobo wrote:

On the original subject of this thread... why doesn't someone calculate an F-16 block 60's wing loading and power to weight ratio? (I think the answer might surprise some who have been advocating building more 4th generation airframes because the F-35 is too F-105-like for their tastes.)

F-16C wing loading figure was around 40lbs per sqft all things considered - the standard calculation doesnt apply to FBW jets with the CG moved - The F-35 figure might not be that far off...

haavarla wrote:

Some material from the Book 'F-15 Engaged'.

Autor: STEVE DAVIES & DOUG DILDY
Steve Davies has written five books on F-15.
He is a full-time freelancer aviation photojournalist, and is widely recognized as a leading expert on modern military matters.

Doug Dildy is a retired USAF colonel who spent nine years of his 26 year career in Western Europe and retired with 3.200 hours flying fast jets, almost half of that as an F-15 pilot.

As Commander of the 32nd Fighter Sq, Soesterberg AB, NL, he enforced the No-fly Zone over Iraq, and acuiring over 100 hours of combat time in the F-15.

This info is for credibility purpose as i'm sick and tired of beeing treated badly by some childish posters in this forum.
I will write down several reports from F-15 engagment, but i will not post 10+ pages, so i will narrow it down.

And i will use Word and copy past it in this thread if it is approved by moderators.

Edit: On second thought, i will post it in a new thread on general Aviation thread..
Stay tuned.

The ODS engagements fail to make your point anyway. Your point is that the MiG and Su have some kind of advantage because of their configuration for low speed turning ability. This presumes that some closer range combat will happen but ignores what matters here which is the quality of HMS/HMD, the presence of EODAS on the aircraft, and missile quality, all of which go to the Western aircraft.

Read up on some tactics some time, especially how the tactics of today are different than ODS.

A little bit on data links and what they mean for combat would help too.

This is seperate issue.
I will not post it in this thread.
I will post this as Flighthawk fail to see there was not as easy to get IFF or VID on enemy contacts during Desert Storm even with several AWACS for support.. is he claims.

On the Flanker vs F-15 low speed handeling, the Flanker gain the edge from 450kn and down, as the speed drop lower than 450kn the Flanker edge over the F-15 rise higher.
This should come as no suprise.
The F-15 has to stay at (relative)higher speed when doing engagement vs F-16, i'm not sure at which excact speed. But if the speed drops below a certain speed the F-16 gains the egde.
Anyway, doing 300-450kn is not slow speed, it is where lots of WVR manuvering happening.
And from 450-600kn the F-15 accellerate faster than Su-27, its due to slightly different transsonic speed regime, allthough the different is not that big.
It flatten out and stay the same up to the 1.9 mach which teoretical the F-15 again gain an edge.
When i say teoretical, sinse both aircraft will have external store, above mach 2 are impossible.

It is on a aerodynamic level i'm debating, i'm not sure why we should take the whole specter in a X vs Y engagement, with the systems that follows.
This is OT as it is.
I was hoping we keep it down to aerodynamics as we started, the tunnel and body liftand wing loading...

haavarla wrote:

That was not what i meant.
What i meant was that the US advocaded the BVR capbiblty and such, look at the F-4 with cannon pod.
But when the real deal was on, the cannon was quite usefull after all.
My point is, the history shows us that the last 100 years the, we are seeing better BVR but its not like the maunfactors claims was happening as advertized.

Havaarla, the fighter planes begun as bi (tri) planes, just to go down to a single wing for greater speed, even though they lost on turning capability.
During the War, jet engines begun to replace propeller ones, to even further increase speed and wings got sweep, for the same reason.
BVR or WVR doesn't have anything to do with that, so I can't figure why you keep bringing that up over and over again.

haavarla wrote:

But there was posters whom said all A2A combat was to happend over 700Kn. No sir that is not correct.
For it to happend, the air engagement have to happend high up at 40000feet+.

Don't make brainless assertions...

Quote:

Just as soon the first turn happening you are way down in KIAS.
There is too much hype about the high speed or even top speed of fighters going on..

About maneuverability...
Last time I checked German Mig29 was capable of 4g (sustained) at M1.5/28kft, F16 - 5g, EF - 7g in the same conditions (F22 probably around there as well).
How do you think the fight between those planes would look like?
If the Mig tries to slow the fight so it can compete in maneuverability, it immediately risks a missile shot.
If it tries to stay fast, again it'll loose comfortably (sooner) against EF/F22, but one g difference against F16 gives it some hope (later).
However, the problem in fighting enemy with higher Ps, is that he can always pull fight into vertical and you can't really do much about it, no matter what aerodynamic qualities you got.

About speed...
Me262 was 20+% faster than allies and was untouchable.
Today even EF is 40% faster than your average non-SC fighter.
Translated into real world figures, that's ~260 KTAS closure rate at 30kft against receding target at lower transonic speed, while both stay in dry power.
In 5 minutes, EF will gain 22nm on a transonic target.
F22 with M1.7+...double that!
How do you plan to engage or disengage from that on your own, is beyond me.

So, you see just because pilots have been drilling one tactic, doesn't mean next generation won't change that.
Obviously, hardware limitations no longer apply (or have been moved) and so the tactics will (and they do) adapt.
Happened in 1944 and is happening today.

To conclude.
Tactics you're citing (combat "<700kn" whatever that means) are a product of hardware limitations and pilots had to devise them to beat otherwise similar opponents.
In a plane that is so superior in basic performance like speed, which allows you to engage/disengage at will f.e., it's really turkey shooting, similar to what Me262 did to Allied forces back in 1944.
(and make no mistake, Mustang outturned Me262 almost across its entire envelope)

There was a smart guy from US, that once said; "...double your speed and you can consider yourself having half the RCS (not literally ofc), from what you had at original speed."

[quote="cola"]

haavarla wrote:

There was a smart guy from US, that once said; "...double your speed and you can consider yourself having half the RCS (not literally ofc), from what you had at original speed."

...and to get down to the F-35's RCS, you'd have to fly even much, much faster than the X-15. A RCS reduction of 0.5 is meaningless and useless. Even the mildly-stealthy Mach 3+ cruising SR-71 was shot many, many times. If it's crusie speed was only < Mach 2 and 60k feet(like a Pak Fa), it'd likely have had more than 'some' losses. No figures publicly exist, but I'd be willing to wager a dollar or two than the F-117 was detected, and targeted, and shot at much, much less times than the SR-71. I wonder how much more the F-35 would cost if its airframe was built to spend all its time at Mach 1.8. That kind of performance comes at a cost - literally a $ cost.

r2d2 wrote:

river_otter, very informative for me, thanks.

But If we think the other way around; In case that you want a supercritical wing you need trapezoid planform for strength (may be???). I mean putting the emphasis on supercritical airfoil rather than trapezoid planform.

IIRC another advantage of trapezoidal wings is the increased structural strength and resistance to bending loads on the wings due to the massive wing root but I'm not quite sure on that. I think someone else with far more experience will have to come on and correct me on that if I'm wrong.

Right, in general long chord wings with more attachments to the fuselage tend to have higher strength to weight characteristics. The relatively short span also reduces bending moment per pound of lift. However, any wing can be designed to have the required strength, just might weigh a bit more. Sometimes surprisingly little weight increase can provide large strength increase. Back in 1975, the original design requirement for the F-16 was 7.33g at air to air combat conditions (4 missiles, ECM pod, full internal fuel). It also had to be able to handle up to 9g at reduced fuel load, and non-critical flight conditions. GD ran a study to see what weight increase would result from 9g at all fuel loads and flight conditions. Result was 22 lb. increase, the AF changed the requirement to 9g everywhere for the 4 missile + ECM pod loading (and downloadings from that).

Here's why. Only a small part of the structure is designed by 9g turn conditions, with the remainder designed by low and high g rolls, sideslips, fuel pressure, inlet pressures, cockpit pressures, takeoff, landing and taxi conditions, gunfire reactions, etc. So to go from 7.33g to 9g, very little of the structure had to be redesigned.

Another good characteristic of wide-chord wings is tolerance for more center of gravity shift. That's not so important for air to air combat, where relatively light weight weapons are launched. But attack airplanes, dropping heavy bombs, will see big shifts in CG. The F-35 heavy weapons are located a little forward of the CG, so the CG will shift aft after they are dropped. That's good for air to air maneuverability, and a wide-chord wing allows more CG shift.

[quote="sewerrat"]

cola wrote:

haavarla wrote:

There was a smart guy from US, that once said; "...double your speed and you can consider yourself having half the RCS (not literally ofc), from what you had at original speed."

...and to get down to the F-35's RCS, you'd have to fly even much, much faster than the X-15. A RCS reduction of 0.5 is meaningless and useless. Even the mildly-stealthy Mach 3+ cruising SR-71 was shot many, many times. If it's crusie speed was only < Mach 2 and 60k feet(like a Pak Fa), it'd likely have had more than 'some' losses. No figures publicly exist, but I'd be willing to wager a dollar or two than the F-117 was detected, and targeted, and shot at much, much less times than the SR-71. I wonder how much more the F-35 would cost if its airframe was built to spend all its time at Mach 1.8. That kind of performance comes at a cost - literally a $ cost.

The point Cola is making is about the importance of speed vs turning.

It's interesting to see how the F-15 is still competitive today despite being quite old because they went for speed. I saw somewhere the STR is only around 15 degrees yet it can still compete in BVR.

F-15 is handicapped by not having scheduled leading edge flap. I think all fighters after F-15 have scheduled LEF. Big difference in low speed lift and stability. F-16 showed the value, and all others followed.

Why did they leave it off?

Forum: General F-35 Forum

JSF High Wing Loading: why?