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Tuesday, August 9, 2011

F-35 Maneuverability Woes

The JSF program was envisioned to create a multi-role combat aircraft capable of both air-to-ground and air interdiction missions, a "strike fighter". This emphasis in dual role capabilities is directly reflected in the F-35's airframe. The F-35 lacks the maneuverability of a purebred fighter such as the F-22A or F-15C. To judge the effectiveness of the F-35 in air-to-air combat, examples from history provide insight.

The aircraft most similar to the F-35 in service with the USAF today is the General Dynamics F-16 Fighting Falcon. The F-16 has been used to great effect in air-to-ground missions during Operation Dessert Storm, Operation Enduring Freedom, and Operation Iraqi Freedom. While the USAF has drawn blood for F-16, most of the 67 kills achieved the F-16 have been done under the command of skilled Israeli pilots. The F-16 has achieved an impressive 47-0 kill ratio under the IAF. Many of these kills were achieved because of the F-16's dazzling maneuverability. This is a key difference between the F-16 and F-35.

Although the F-16 was intended to be a dual role aircraft, one of the stringent requirements of the F-XX program was for the new aircraft to feature high trust-to-weight ratio. This resulted in the F-16 being one of the earliest fighter aircraft to enter service with a thrust-to-weight ratio exceeding 1.0. The F-16's already spectacular maneuverability was enhanced further with the implication of revolutionary fly-by-wire technology. This degree of maneuverability provides the Falcon with lethal visual range combat capabilities. In contrast, the F-35 was rated as "Double Inferior" in regards to both vertical and horizontal maneuvering capabilities relative to modern Russian and Chinese fighter aircraft such as the Su-27, Su-30, Su-35, Mig-29M and Pak Fa. In fact, the RAND report went as far to say the F-35 has "Inferior acceleration,inferior climb,inferior sustained turn capability" relative to the compared aircraft. This lack in maneuverability is not something that incremental upgrades can solve over the F-35's service life. Rather, they are the permanent result of the F-35's design. Airframe design cannot be changed.

Thrust-to-weight ratios of fighter aircraft; 100% fuel followed by 50% internal fuel
All following calculations assume aircraft thrust using afterburner

F-35A .87 -> 1.07
Su-27K 1.07 -> 1.21
PAK FA* 1.19 (exact figures unknown as final version will feature different engines)
F-16C 1.095 -> 1.25
F-22A 1.08 -> 1.26

Instead of giving the F-35 a high thrust-to-weight ratio and high maneuverability, the design team at Lockheed placed their faith in Helmet Mounted Display (HMD) technology. The HMD allows pilots to literally look at a target to achieve missile lock. With the advent of off-boresight capability missiles such as the AIM-9X, pilots can look at aircraft up 90 degrees away, gain missile lock, and score a kill. If the HMD works as advertised  it could revolutionize the dogfight. However, if the HMD is not able to mitigate the extreme maneuverability of its opponents, that the F-35 is at disadvantage. The last time this much faith was placed on new technology without any back up plan was during the Vietnam War.

In the years prior to the Vietnam War the USAF developed a new theory that beyond visual range (bvr) missiles would be the future of the dogfight and that the traditional weapon of air superiority platforms, the gun, was obsolete. (RAND, 2008)It was also believed that aircraft did not need to be maneuverable as the missile would do most of the maneuvering from range.(APA, 2010) As a result, the F-4 Phantom was not maneuverable and did not feature a gun. Two missile designs were fielded by the USAF during the Vietnam War. The radar guided AIM-7 Sparrow which had a range greater than 20 miles was built for bvr engagements. The AIM-9 Sidewinder missile was designed for visual range combat and had a range of 2.5 miles. The USAF put their faith in guided missile technology and did not equip the F-4 Phantom with guns. The Pk (probability kill) of AIM-7 Sparrow missiles during tests was .70 but during combat the Sparrow had a Pk of .08. Thus, Vietnamese Migs were 100 times more likely to get within visual range and initiate a dogfigt than expected. (RAND, 2008)The Sidewinder did not fare much better with a combat Pk of .15. This spectacular lack of foresight lead to pilots being defenseless without any back up. As a result, pilots had gun pods attached to the F-4 latter in the war. In essence, the lesson learned was that new technology and tactics should always be used in conjunction with older proven technology and tactics in the event that Murphy's law comes to fruition.

The counter point to the argument that the F-35 needs maneuverability is that the F-35 is stealth and enemy fighters would not be able to get within visual range. This assumption is unrealistic. The F-35 will be able to destroy 4.5 generation threats from the comfort of bvr in all likelihood. However, the real threat for the F-35 is against other 5th generation stealth fighters such as the Pak Fa. Because of its stealth, the Pak Fa would not be detectable by the F-35 until it was within 30 nautical miles (estimate using frontal rcs) while the Pak Fa would detect the F-35 at 28 nautical miles. (APA, 2009)If both aircraft are speeding towards each other at mach 1.5 they would be on top of each other in just over 50 seconds. Visual range dogfights are MUCH more likely in the event the JSF is faced with a 5th generation opponent. In which case HMD technology better work. It would also not be out of the question for the Pak Fa to feature an HMD of its own, operational Mig-29's and Su-27's already do. The F-35 has the potential to win the fight but its going to be a lot closer than it needs to be. The F-22A has BOTH high maneuverability PLUS it will be upgraded with HMD technology.

A fight with the F-35 vs the Pak Fa will be close and will likely come down to the skills of their respective aircraft. There is one major component that rests in the F-35's favor and that is avionics, specifically the radar arrays. The Pak Fa is in all likelihood going to use a 1,500 TR AESA array. The new array will likely be an improvement of the NIIP Irbis-E or some evolution of the system in conjunction with other secondary radars. The Irbis-E has 1,500 TR nodes effectively meaning it has more "detection power" than the 1,200 TR F-35 AN/APG-81 AESA.  The vulnerability of the Irbis-E is compounded further by the fact that it is not a low-probability-of-intercept radar(LPIR). Russian engineers do not have a comparable the level of experience in designing LIP radar modes using emission control principles. In tests the APG-81 was able to jam and track even the LPIR of the F-22A (AN/APG-77)

In a series of tests at Edwards AFB, Calif., in 2009, Lockheed Martin’s CATbird avionics testbed—a Boeing 737 that carries the F-35 Joint Strike Fighter’s entire avionics system—engaged a mixed force of F-22s and Boeing F-15s and was able to locate and jam F-22 radars, according to researchers. - Aviation Week, 2011

If an F-22A with LPIR is vulnerable to the F-35 jamming it, essentially greatly reducing detection abilities, than the Pak Fa without LPIR is that much more vulnerable. As for vulnerability to jamming, the AN/APG-81 has an extremely high resistance to being jammed. In fact, the AN/APG-81 won the David Packard Excellence in Acquisition Award because of its performance against jamming. This ability to jam and track a Pak Fa might end up being what gives the F-35 the edge. Either way, it will be too close for comfort.

Further Reading (links)

Canada and the F-35
Murphy's Law: F-35 Development and Performance Concerns












  1. Fascinating stuff. The F35 needs to be canceled I think. Rather than a mulit role aircraft we should have specific flyoff competitions so that the aircraft won't have design compromises. A dedicated dogfighter and a dedicated ground attack jet would end up being much much cheaper, and far more effective in combat. The F35's advanced tech that gives it an edge can probably be used on any airplane for a fraction of the cost. As nice as the HMD sounds, we still don't know how reliable it's going to be in a furball, and not having the ability to turn with a Sukhoi is going to be a big problem.

  2. I'd probably agree with you before the start of the JSF program but at this point its too late to back out. A dual role fighter can excel in both roles e.g. F/A-18E, F-16 but the F-35 was just given way to many requirements. The same basic design had to allow for both the strike role and vertical take off and landing (plus carrier landing too). If you slap too many requirements on a project you just end up with a mess. This happens a lot within the military. Another example of this phenomenon is the Littoral combat ship program.

    1. i agree. the su-27 and the mig-29 came out of the same program cuz there was too many requirements for just one aircraft. Look how they turned out

  3. I heard that the F-35 has a slightly better turn radius than the F-16 and F-18. I don't where you are getting your information from. The Rand report was proven to be false, based on F-35 critics bias and misinformation. The facts are simply the F-35 will out turn all fighters with the exception of the F-22 and maybe the Eurofighter.

    Get you facts straight.

  4. If you don't mind me asking, I would like to know where you get your figures from. I'm happy to read counter arguments but I need data. Preferably more than one data source that independently arrived at the same conclusion as yours. Furthermore, depending upon how you define maneuverability (e.g. wing loading, thrust-to weight ratios, sustained radius turn ability, etc)most of the reputable sources available indicate that the F-35 is just not that maneuverable. Given its objectives as laid out in the JSF program in the 1990s, it makes sense. The F-35 had to be able to preform strike roles as well as an air superiority AND remain viable for VTOL. With this many requirements you have to compromise certain aspects in design to achieve your goal especially when cost is an issue. The F-15 is an example of an aircraft with a singular purpose, air dominance, and it's a remarkable success in that regard.
    I wrote a more up to date article with 30+ sources named on the F-35 called "Murphy's Law at Work: F-35 Development and Performance Concerns". I go much more in depth with maneuverability as well as other issues. If you don't believe me read the official declassified version of the QLR report from the DOD itself. The link:

  5. F-35 Jack of all trade and master of none, too much compromise in my opinion. But still top gun and red flag can train pilots to overcome its flaws and utilize its strength. We done it before in vietnam. With PAK-FA and J-31 air superiority fighter, along with J-20 long range interceptor; USN/USAF shouldn't put all its bread in one basket. A F-22B that incorperate APG-81,3D TVC, HMD and redesigned G-suit/life support is a comfortable plan B.

    The fact that engineer at lockheed designed a next generation fighter that can only dominate gen 4 fighters indicate a tremendous lack of vision and foresight. Russian and chinese has a chance to reverse engineer APG-81 from a possible downed F-35 and incorperate into PAK-FA and J-31, but F-35 would never be able to improve its agility. With the exception of F-35B, this plane is a waste of tax dollars that can be better spent on F-22B.

  6. I would love to see F-35 out perform rival aircraft from Russia and China, but the fact suggest that is not the case. We might be looking at a 21 century equivalent of the F-4 phantom.

    1. Well until we get some mock dogfights underway, it will be hard to say for sure how bad or good it is. But nearly all the paper evidence put forth by thinktanks and the D0D itself suggests it won't be maneuverable enough. Even with superior pilot training, we lost more aircraft in Vietnam that we needed to. It is always best to have aircraft specialize in a role and do it efficiently rather than to construct a general purpose aircraft that can't preform well. I wrote about many of your concerns and possible upgrades for a F-22B in Murphy's Law at Work: F-35 Development and Performance Concerns. More on the PAK FA is in Threat Analysis of Foreign Stealth Fighters Part II: Sukhoi PAK FA.

    2. Well, it's interesting coming back to these comments with the red flag results now.
      17-1 kill to loss ratio at red flag. Not only that but thrown up against some of the best IAD the excersise has to offer. I think they have a killer on their hands. It's great to have it all confirmed I have to say.

    3. People will still continue to doubt the F-35 even with these great results. At this rate, the F-35 could beat the F-15's 104-0 kill to death ratio in a major shooting war and F-35 critics would still argue its a terrible aircraft!

  7. One thing to correct here, the PAK-FA radar is not a PESA as on the Su-35, it is an AESA radar, look it up on the internet.

    1. There is no set contender for the PAK FA's radar at the moment. Furthermore, things have changed since this article was posted. A more comprehensive and recent post on the subject of the pak fa:

  8. APG-81, 1672 T/R ?

    1. I know some folks at counted and found 1,676. It could very well be greater than 1,200. For a long time, official sources claimed 1,500 T/R for the APG-77 but there is pretty conclusive proof its around 2,000.