agruements and data, not flaming…please..
We are trying hard to do just that you see… đ
F-35 Lightning II News
Weighing the F-35
March 16, 2008 (by Eric L. Palmer) – Weight in the design of aircraft has always been a curse to aerospace engineers. The F-35 is no different. Here are a few points to consider when the topic of F-35 weight comes up.
What are the different kinds of aircraft weight? Peter Goon, an Australian flight test engineer has some thoughts:
“One can track the weight growth of the JSF by going back and looking at the design IOC target weights for all variants for design configurations 240-1. 240-1, 240-3, 240-4 .
These are design target weights and there is likely a 3% margin on top of these.
Are these the Design Empty Weight of each variantâŚâŚor are they what is called the Basic Empty Weight for each variant (which includes the unusable fuel and undrainable oil, survival equipment, etc) âŚ..or are they the Operational Empty Weight for each variant which is the Basic Empty Weight + weight of crew, weapon racks, ejectors, rack adaptors, gun and everything else for the operational mission except the actual weapons and fuel?”
The table below [1], points to some of the early weight history of the F-35 program.
Weight may be one of the easiest factors of combat aircraft design for a non-engineer to understand. It has significant effect on how much fuel, weapons, and mission equipment the aircraft can carry. This means that when excess weight appears in the design, the aircraft will be limited on how far it can fly, how much agility it will possess, how many targets can be hit with what effect and how well the aircraft can detect threats and defend itself.
The 2004 event addressed by the SWAT (STOVL Weight Attack Team) was the result of discoveries that the STOVL (Short Take-Off Vertical Landing) variant of the JSF known as the F-35B was at risk of not meeting its weight requirements. So much so that this variant would not be able to accomplish its mission unless there was a serious reduction in aircraft weight.
The SWAT event was mostly solved by reducing the F-35B STOVL mission requirements. All three variants had a design specification to carry two-each internal air-to-ground weapons in the 2,000 pound class. A weight savings on the F-35B STOVL was achieved by changing the internal carry of this variant. SWAT proposed having the STOVL variant to carry two 1000 pound air to ground weapons. This produced a weight reduction of 2000 pounds. The main âcustomerâ, the U.S. government representative and coordinator for F-35 worldwide customers known as the Joint Strike Fighter Program Office was told that either some design compromises would have to be agreed upon to allow the aircraft to fly or the STOVL variant may fail. The customer agreed. Another 700 or more pounds of weight were reduced by changing the design of numerous items on the aircraft. These combined efforts of SWAT also reduced weight from the other two F-35 variants by about 1300 pounds.
The result of the SWAT effort, while saving the STOVL to fight another day in the design process had some negative effects too. The above mentioned design changes had a great effect on the production line process.
So from all that, a weight problem on one variant, changed the production process, produced huge delays and caused a rise in the total cost of the program.
While the 2004 SWAT episode may be the signature F-35 weight reduction event, there were signs of these problems a year before. Back in 2003, Lockheed Martin announced that an earlier weight reduction event had shed 1000 pounds off the design. The down side is that “make joints”, appliances that made aircraft assembly efficient, were removed from the production line procedure. This would add several days time to the production cycle. Tom Burbage, Lockheed Martin’s director of the Joint Strike Fighter Program stated: “That was the trade-off we had to make to get the weight down”. [2]
When the AA-1 test vehicle F-35 was rolled out in 2006, one Lockheed Martin official stated: âThe weight of this F-35A is greater than what was originally projected, but not so high that the aircraft does not meet key performance parameters. The margins would be very tightâthey are not wide, even with the redesignâbut it would have made it. Every F-35A that follows will be lighter.â[3]
Weight growth will be critical to making the whole F-35 program sink or swim. The conventional take-off and landing (CTOL) variant the F-35A offers the least weight resolution problems. Like an F-16 or F-15 or other similar conventional runway fighters itâs launch and recovery issues seem easy. What wonât be easy is that the other two designs have to demonstrate a short-take-off and vertical landing (F-35B) and do all the difficult launch and recovery tasks associated with the demanding carrier aviation environment (F-35C).
While Lockheed Martin is hoping to contain weight growth to 3% of the design, other experts have chimed in and stated historical growth in past combat aircraft designs have been as much as 6%. [4]
On March 14, 2008, the U.S. Department of Defense announced a $70 million dollar contract to develop weight reduction for one of the F-35 engines: The Pratt & Whitney F-135. [5]
With two of the three F-35 variants having demanding take-off and landing requirements, weight-growth containment will be the nemesis for F-35 design engineers for the foreseeable future.
End Notes-
[1]Peter Goon,Notam No.1, The Biggest Loser,, Air Power Australia, April 4, 2007, Retrieved March 15, 2008,
[2]Bob Cox, Team Seeks Weight Loss for F-35 Joint Strike Fighter, Fort Worth Star-Telegram, June 19, 2003
[3] Joe Pappalardo, Weight Watchers, Air and Space Magazine, October-November 2006, Retrieved March 15, 2008, “Design and assembly changes, mostly related to the SWAT recommendations, have cost about $4.8 billionâpart of a $6.2 billion replanning to accommodate the additional design cycle required to make the improvements. The replanning forced an 18-month slip in F-35 deliveries. According to a 2006 Government Accountability Office report, since inception, the development costs of the JSF program have increased 84 percent and its timeline slipped by about five years. The STOVLâs final delivery deadline has been extended two years, to 2012.”
[4] U.S. Government Accounting Office (GAO) -, GAO-08-388- Joint Strike Fighter: Recent Decisions by DOD Add to Program Risks, (Table 6), – March 11, 2008 Report, http://www.gao.gov ,Retrieved March 15, 2008
[5]DOD Contract, March 14, 2008, retrieved March 15, 2008,
http://www.f-16.net/news_article2784.html
http://www.dassault-aviation.com/en/defense/rafale/aircraft-characteristics.html?L=1
In the offer to Switzerland the claimed empty equipped for the Rafale was over 10 tons.
http://www.rafale-schweiz.ch/images/stories/pdf/Rafale_Technical_D.pdf10.220 kg or ~22500 lb for the F3 standard compared to 13.330 kg or 29300 lb for a F-35A first Block example if that can be kept at all.
Every fighter is gaining weight through development. The former specification for the F-35A were 11340 kg or ~25000 lb as 9100 kg or ~20000 lb for the Rafale C F1 standard.
Dassault source: Ten to class EQUIPED and NO Rafale C was presented to Switzerland, the aircraft that flew there are about 220 kg heavier and the M weights- 10 196 kg = <> 650 kg extra.
http://www.defense.gouv.fr/marine/decouverte/equipements/aeronefs/rafale_m
“offer to Switzerland” we’re talking empty weight EQUIPED (which you carefuly avoid to say) so this other legend about Rafale empty weight increase is just that, another legend.
Standard F2 was release long before the publication of this DGA document and there is no =diffeence in weight between the F2 and the F3 standard, only software changes.
And definitely NO Rafale didn’t put on weight as opposed as what you alleged (how convenient would it be for the Typhoon and F-35 fans?).
Are these the Design Empty Weight of each variantâŚâŚor are they what is called the Basic Empty Weight for each variant (which includes the unusable fuel and undrainable oil, survival equipment, etc) âŚ..or are they the Operational Empty Weight for each variant which is the Basic Empty Weight + weight of crew, weapon racks, ejectors, rack adaptors, gun and everything else for the operational mission except the actual weapons and fuel?”
Weighing the F-35
http://www.f-16.net/news_article2784.html
Source:
Weights. Masse a vide Rafale C = 9.5 tons.
F-35 A weight is given EMPTY by L-M as is the case for all variants.
We know what the empty weights of all Rafale variants are, we have other official datas and we also know the weights of; pylons, tanks, weapons, pods, ejection seat etc.
Apparently you don’t. :rolleyes:
Sorry but I just HAVE to respond to this troll…
So do I:
That is the worst kind of trash journalism.
WAY Better informed than yourself apparently.
The author can’t even get the thrust of the F135 correct. The F135 is rated at 28,000 lbs dry (military) & 43,000 lbs wet (afterburner) thrust.
First: F-135 havent always been rated at 43,000 lbs, check the date of the article.
Second: Turning performances are computed according to these parameters:
High Air Density.
Low wingloading.
Hich Lift Coefiscient.
High Structural Load.
Now please EXPLAINT to us how F-35 configuration 240-4 will do any better with a lower Structural Load?
Then there is the little matter of changes involved like the deletion of the LEX which was meant to generate the lift needed to increase turn rates…
After this is you wish you can add thrust vs drag to compute a sustained turn rate from a lower instantaneous turn rate, it won’t make the later better nor give you a higher sustained turn rate.
The F-35’s frontal area is similar to that of the Rafale (as is it total surface area)
đ đ đ !!!
Sure! Everyone knows that Rafale posses an internal weapon bay too! đ
yet I have heared no complaints of the Rafale’s acceleration with LESS thrust than the F-35 (no I am NOT saying that the F-35 is a ‘aerodynamic’ as a Rafale, I AM saying that is is about the SIZE of a Rafale).
Acceleration are not a question of thrust but foremost critical Mach giving you a drag coefiscient.
Critical Mach is defined by the sweep angle, with 33* F-35 have a far higher drag ratio than a Rafale in all flight regimes with a 48* sweept wing.
As for its TWR you might find that F-35 is WAY below Rafale C at their respective empty weights:
F-35 A TWR Empty —– = 1.247.
Rafale C TWR Empty — = 1.578.
Lets see any remotely comparable fighter ‘dogfight’ with that kind of load!
Rafale C is WAY lighter than F-35 A (20.943lb vs 29.300lb), and so logically should carry LESS but what matters here is the load ratio…
Rafale carries 1.5 its own weight, F-35 canot match this yet (equivalent to 73.250 lb), alternatively compare F-35 to a B-52 if you please.
And even with external stores the F-35’s radar & IR signatures are superior to comparable 4th or 4.5 generation fighter with a similar payload.
đ
F-35 IR signature is effectively WAY superior to that of Rafale by virtue of the world’s hotest running engine featuring NO cooling system whatsoever.
M 88 is conceived from design stage with a ram-air system cooling both the engine case AND the internal engine bay from the front to the end of it (including Post combustion chamber).
It also posses a double con-di nozzle cooling the hot jet and shielding the internal set of con-di nozzles from a far higher angle.
Note, however, it is advantageous for potential enemies & ingorant fools like Cola1973 believe the so called data for the 230-3 design accurately represents the performance of the actual F-35A (so I may have exposed a deliberate deception but a I am certian that Cola1973, Dare2 & other such fools will chose to believe the deception). ;)[
The “fools” knows their basics, some others pple in the other hand doesn’t, and apparently doesn’t bother reading their own post either. đ
Sens
For the benefit of the others.
http://www.codeonemagazine.com/archi…july1a_95.html
A pilot has not to learn the different Mach limits for that weapon for every height, just the single IAS-limit!
Right! LOL.
First; your source says nothing of the sort.
Second; you manage to get your datas crossed and mix low-level A2G subsonic speed limits for high-altitude/high-speed A2A weapon flight and firing envelops, if this graphs are there it is for the purpose of the pilots learning them.
It was simple enough to look at the graph, though because THIS is what “A pilot has to learn” NOT what your funny interpretation of it might be, they would be looking at Mach at high altitudes NO Airspeeds.
Result: Either you do it on purpose either, you really don’t understand what you read and write.
For the benefit of the others, the Mirage III flight manual gives speeds in kt for altitudes at up to 33.000 ft and Mach above that, the other lower, subsonic limits are given in kt, the Mach scale is at the bottom of the Graph.
IAS airspeed aren’t even quoted in the whole manual.
Sign In
