FBWAs i already posted, there are several factors, none of which favor F-35 in the transonic regime,
by Mach 2 there is also no longer advantage in swept wings, and even F-35 will have exit transonic regime by then.
I really recommend you read up on NASA studies, links posted on earlier page
Actually I looked up quite a few articles before I posted previously on your wing sweep chart. I make an effort to provide links for facts and express opinion as just that, an opinion. What I stated before still holds true: your assertion –“that As we can see, all fighters has a wingsweep of 40* or more…but wait, there is an abomination, we find that one has a wingsweep closer to 30, 33 to be precise.”, is a gross generalization. I’ve attempted to show that logic is simplistic, I wonder if you actually read your NASA link as it points out the relative disadvantages for wing sweep. Obviously, if you were designing a fighter that had a requirement for uncompromising mach 2 performance, you would choose a highly swept wing. The F-35 is a multi-mission aircraft and has a low aspect wing. Like most aircraft there is a compromise between supersonic and subsonic performance.
You have a right to your opinion about the F-35, but blanket statements “like its predecessor F-117, it has the designation F, but it is not a fighter, it is an evolutionary subsonic bomber but with much better self defense aid, even able to go supersonic if given enough time.” are not supported by fact http://techdigest.jhuapl.edu/TD/td1801/steidle.pdf
Another example of a blanket statement- “As i already posted, there are several factors, none of which favor F-35 in the transonic regime”, Again not supportable http://www.airforcemag.com/MagazineArchive/Pages/2012/November%202012/1112fighter.aspx, “There is a major extension of the fighter’s range if speed is kept around Mach .9, O’Bryan went on, but he asserted that F-35 transonic performance is exceptional and goes “through the [Mach 1] number fairly easily.” The transonic area is “where you really operate”. The F-35 was designed with transonic performance in mind.
The issue goes back to the initial RAND study and APA smear campaign. The “Anti” crowd make the same disproved assertions again and again as if repeating things like “The F-35 can’t climb, can’t turn, can’t run” will make their statements true. I am not a unconditional supporter of the program, but there is a difference between fact and opinion. People want to knock the program for being late, over budget, or threatening to domestic defense companies, fine. But claims that the F-35 is not a fighter aircraft because it is not their idea of an air-superiority fighter ala F-15, SU-27 etc, ignores the design goals of the program. It’s a “Strike” fighter and hopefully a good one. Some will continue to claim that a duck isn’t a bird because it doesn’t look like tweety,but it does not make it true
FBW[QUOTE=halloweene;2100533]yes, but it also enhances instability on 3 axes which is not desirable (vs instability on 2 axes)
Why would having the load closer to the center enhance instability? That makes no sense to me (you may be right).
@ Obligatory- Wing sweep again, it’s not the only factor. Consider this, for an aircraft travelling at mach 2 in order to stay out of the mach cone, it would need a sweep of 60*. By your reasoning there would be no mach 2 aircraft.
Wing sweep is important, but it depends on the type of wing, length, thickness. The F-35, as many detractors gleefully point out has stubby wings. This was a requirement of the Marines. But look at its aspect ratio (f-35 2.66, f-104 2.45, f-16 3.09) The wingspan of the f-35 is 35 feet, the f-16 is 33 feet. The U.S. seems to prefer the trapezoidal wings, and if speed were the only factor to consider in a fighter, they would all probably be deltas. That relatively short wing may not need to be as swept as say, a delta. It may stay out of the mach cone longer.
That could, in fact, be one reason for the f-35 being limited to mach 1.67. There could be a large rise in wave drag around that speed as the wings come into contact with the mach cone. Then again, the speed limit could be a thermal issue: We know the f-35 had time limitations on afterburner, the f-135 operates at a hotter core temp than any other turbofan engine, so that could be a factor. It also could be that the requirement was set at mach 1.6 and there is no desire to spend the money or time in high speed tests above the designed speed.
FBWOne thing forgotten is that the f-35 carries it’s weapons close to it’s center of gravity. Most fighters have to worry about g-loads after expending ordinance due to asymmetric loads on the wings. Carrying that load internally mitigates some of the performance degradation that results from carrying ordinance on the wings (think figure skater). No, the aircraft is not immune to inertia, but people underestimate the drag factor of external loads. The designers don’t shape the aerodynamics of an aircraft based on weapns it will carry, they are based on a clean aircraft. That’s why weapon certification is so important (lest we forget the debacle of the F-18E/F weapon separation problems). The point is, anyone who has ever stuck a ski rack on thier car knows that even small additions impact the overall aerodynamics. If the aircraft is not carrying the weapon internally, or at least in a semi-conformal attachment, there will be an impact on performance. And yes, the aircraft was to meet it’s top speed with full internal load, though the 9g rating is for after air to ground ordinance is expended. http://www.lockheedmartin.com/us/products/f35/f-35a-ctol-variant.html
FBWNo, i’ve only seen guesstimates of the fuel burn on those. To compare the two you would need drag and fuel burn at comparable speeds. Apples to Apples comparisons would be difficult with sketchy numbers from the F-22 and non-exsistant information on the NG other than a press release of super cruise at m 1.2 http://www.defenceweb.co.za/index.php?option=com_content&task=view&id=1010&Itemid=350 I am not knocking the Gripen, which I think is a fine aircraft. It makes sense for any nation that’s primary mission is air policing. It was a natural fit for Brazil and I applaud their choice. Most Nato nations have coalition missions in mind, the’ve by and large chosen the F-35.
FBWFirst of all, quoting a David Axe article is really not credible, though you could give him credit. Love how you edited it to make it look like Gen. Burton Field said it was a mediocre performer. And yes, as I stated above I don’t think the F-35 has any useable super cruise. As far as the Gripen NG goes in comparison to the F-22. You have the bypass ratios above (F-22’s is from Jane’s a credible source for sure, but truthfully P&W has never listed the bypass ratio or pressure ratio of the f-119) As for fuel fractions, http://jas39gripen.blogspot.com, this is the one source I could find on the Gripen (.31), the F-22 fuel fraction is (.30) give or take. I don’t think there is any way that you can make that assertion about the Gripen NG, still in development, being superior supercruise time to a fighter that’s design and engine was built around that as a cornerstone as the F-22’s was. The f-414 is a fine engine, but there is a reason why simple thrust numbers don’t imply super cruse efficiency. How I count is in numbers…
FBWBypass ratio of f-135 is .57, very high pressure ratio 28. This thing pumps out a lot of power efficiently at subsonic speeds. Not the specifications for an engine that’s going for high mach numbers. I’ve read the test pilot comments about the F-35 achieving super cruise many times, my take has been that the aircraft was always designed to live that mach .8 to 1.2 region. Faster than legacy aircraft cruising with a weapons load, designed to maneuver in that range. There is a high penalty to be paid in designing an aircraft that can achieve mach 2 speeds in materials, aerodynamic heating, wing design. Some of these are penalties are not complimentary for a multi-role fighter that is supposed to achieve good range.
FBWBTW, the F-35 wing sweep is 34*, and you forgot to point out that a trapezoidal wing such as the f-35 and f-22 are different from a delta wing. I suppose the low sweep of an f-104 shows that it was a low speed bomber too! Oh, wait.
FBWTransonic regime differ greatly from design to design, pending on wing sweep, aspect ratio, twist, thickness to cord ratio, and area
all of these favor deltas
F-16 have a wingsweep of 40*
F-22 42*
Rafale 48*
YF-22 48*
Typhoon 53*
Mirage 2000 58*
Su-27 42*
MiG-29 40*
F-35 is 33*
Gripen is 43*
F-15 is 45*As we can see, all fighters has a wingsweep of 40* or more…but wait, there is an abomination,
we find that one has a wingsweep closer to 30, 33 to be precise.
Much like its predecessor F-117, it has the designation F, but it is not a fighter,
it is an evolutionary subsonic bomber but with much better self defense aid, even able to go supersonic if given enough time.http://history.nasa.gov/SP-367/chapt5.htm transonic
http://history.nasa.gov/SP-367/chapt6.htm supersonic
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Yet that does not tell the whole story. Sharply swept wings are less efficient for turning in the transonic regime. Your own chart shows that the wing sweep of the YF-22 to the F-22 was decreased for this very reason. The sweep was decreased and the airfoil was thinned to make up for it. Saying that the F-35 is not a fighter but a supersonic F-117 replacement is inaccurate. It was ALWAYS supposed to be a multi-role aircraft with an original 60-40 split between air to ground and air to air requirements. With the truncation of the F-22 procurement, you can bet that the USAF looked into the effectiveness of the F-35 in the air to air regime. Lastly, the supercruise argument is a little absurd. The F-22 really stands apart from all others for two reasons, it’s fuel fraction allows for a tactically significant super cruise (some would argue barely enough), and the bypass ratio of the f-119 allows it. The others may be able to achieve speeds above mach 1 without afterburner, but not efficiently. Hell, the f-106 could do that. Bypass ratios ( f-414: .34, f-100: .36, Ej-2000: .4, M88: .3, F-119: .2 or .15) Yes, I sourced them mostly from manufacturer data except F-119 that comes from clancy and sweeten. (see correction below from mercurius, Jane’s says .3 so that’s probably accurate)
FBWTalk about the ambivalent view….http://nationalinterest.org/commentary/will-the-f-35-dominate-the-skies-9618, this is the anti- Bill Sweetman. Have to give this guy credit for not making an absurd pronouncement either way.
FBWThis is the battle of the future, expensive LO UAS’s or swarms of low cost UAS’s. The F-35 has a niche here but the B version will be losing ground, the Marines cannot justify 340 of the latter. http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_12_23_2013_p14-647638.xml&p=2, The Navy had better embrace both the F-35C and a UCAS, lest they find themselves in a worse TACAIR shortage than they currently face.
FBWThe concept of the stealth compressor stage is interesting, but what about bird strikes on a totally composite engine? what is the nose cone of the centrifugal impeller made of? Surely that can’t be RAM material too, can it? The cowling of the turbofan is not metal? Any of these would cause a spike in RCS. The idea of the blisks not reflecting radiation goes against the long held view of SHAPE, SHAPE, SHAPE, materials. I’m guessing there will be a radar blocker.
FBWagreed, this is not the 1980’s when NATO nations were supposed to devote roughly 3.5% of GDP to defense. I also can’t imagine a “go it alone” approach like the Rafale getting funded today, bar upgrades like the Gripen NG and upgrades to Rafale and Eurofighter (latter multinational).
FBWLockheed did state that the original specifications were for a longer aircraft, probably it would have helped with area ruling as well. http://www.flightglobal.com/blogs/the-dewline/2013/01/pentagon-lowers-f-35-performan/
The key question to ask about “joint-ness” would be what aircraft would survive today’s defense budget. Had they decided to go with three different airframes, I’m going to guess that the only survivor would have been the air force version. Navy has/had the Superbug in production, the Marines were not going to get a STOVL aircraft of it’s own design. The problem was the freeze placed on aircraft production/development at the end of the cold war. Block airframe fatigue is not going to be solved long term and thirty year old airframe designs are not exactly a wise investment post 2020. Anyone here drive a car from the seventies as a daily commuter? My issues with the F-35 as a program have more to do with the oversight from 2002 to 2010, and the weight growth that will eat into airframe life, range, and upgrade weight margins. The A model should not have exceeded 28,000 pounds, ever. In retrospect, there is no way that all three U.S. services and partner nations would be able to recapitalize their fleets with anything other than a “joint” program.
FBWThat’s the point that seems to be missed the majority of the time with the F-22, F-35. The design of these aircraft includes large internal fuel capacity. A Mig-29 with 50% internal fuel left had better be headed for home, an F-35 with 50% will have 9,125lbs of fuel (.7- 0.886 lb/HR/lb st, estimates), that works out to between 37 and 46 min flight time at mil power (a simplistic estimate for sure). The x vs y comparisons based on wing loading and thrust to weight ration that are commonly seen on threads might as well be comparison of which looks prettier without all the factors that influence an aircraft’s performance figured in. And frankly, as I’ve tried to point out repeatedly we just don’t have enough information to correctly predict F-35 performance.
(BTW, I know that there are several numbers out there for the loaded weight of a Mig-29, the rough numbers are just to show that comparisons of wing loading and thrust to weight are not empirical evidence of anything, other factors are equally important- high lift devices, drag, fuel, wing design… not telling people anything they don’t know)
FBWit has higher wing loading than the F-104… (not to speak of eurocanards or, if you prefer US references, any more or less modern US design). Somehow, I have some difficulty associating that “feature” with an aircraft supposedly considered as a “good dogfighter”… it may eventually be able to manage to pull up to 9G’s, but if it does so at twice the speed that its adversary of the day needs, it will rapidly be in deep trouble (and don’t talk to me about over-the-shoulder shots to save the day, as pretty much any modern air force has, or is getting, that capability – which depends mostly on the missile used – by now)
anyhow, again, guys keep comparing what they hope the F-35 will deliver years from now with capabilities demonstrated by others years ago as if it was today’s reality…
Wing loading…. Has to be the most abused statistic as far as comparing the “maneuverability” of modern combat aircraft. As quoted by Disraeli “lies da**ed lies, and statistics:
Mig-29 loaded weight 37,000lbs, wing area 409= 90.4 lbs/sqft
F-35 60% fuel+ 4 amraams 41,420lbs, wing area 460= 90lbs/sqft
(fuel fraction for Mig (full fuel .323), F-35 .375 at 60%)
Don’t recall anyone claiming the Mig was a dog in a Knife fight
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