Why Don't Fighter Jets Use High Speeds (Mach 2 and Above)?

Fighter Jets and Speed Factor

The jet era in air warfare began with the use of the German Messerschmitt (Swallow) Me 262 turbojet engine aircraft in 1944. With the end of the war, great advancements were made in fighter aircraft in a short period of time, and jets were rapidly adopted from the early 1950s onwards. The Turkish Air Force had the opportunity to modernize virtually all of its fighter aircraft with American-made fighter jets from 1953 onwards.

When we look at fighter jets in terms of the speed factor, the speeds of jets have remained almost the same from the past to the present, and there has been no need for fighter jet designers to increase speed.

Perhaps this is why, with the exception of the F-35 and the F/A-18 E/F Super Hornet, most modern fighters were initially designed to achieve speeds of at least Mach 2. Especially for fighter/interceptors designed to gain air superiority (F-15, F-22, SU-35, MiG-31, Eurofighter Typhoon, etc.), Mach 2 is a desirable speed. Why 2 Mach as a speed? Aircraft manufacturers had already reached this milestone in the mid-1950s. There are specially produced intelligence and interceptor aircraft that are required to reach higher speeds, but their number and utilization rate have remained very low. As such, the hysteria for high speeds has gradually faded into the background.

Let us ask some questions and try to find answers to them in the rest of this article: Why haven't fighter jets gotten faster, contrary to expectations? Why did they even find it necessary to slow down, as we have seen in the case of the F-35? Why did even the F-16s have to adapt to this change?

High Speed Means Spending Extra Money

In terms of fuel and maintenance hours, going to higher speeds requires more resources. It is expensive. In addition, speed in itself does not provide the tactical advantage it once did. Requirements such as position and kinetic superiority, which used to be achieved with fighter aircraft, are about to cease to be a necessity. In place of aircraft, most modern air-to-air missiles are already taking over the kinetic workload in air combat. Missiles have taken over this requirement from airplanes. 

In the early years of fighter jet development, higher speeds were required for the intended missions and survivability. Performance was the primary expectation. Later, advances in technology and tactics largely replaced performance for these purposes. The F-104, MiG-21, Mirage, MiG-25, MiG-25, F-4, etc. jets, which are among the fastest of the second and third generation fighter jets, were originally designed to intercept the high-flying strategic bombers carrying nuclear weapons of the Soviet and American sides in the Cold War environment. In order to use their weapons and rockets/missiles with ranges that are quite short in today's conditions, these interceptors had to be able to reach high altitudes as soon as possible, and to do this, they had to use high speed. In this sense, the MiG-25, probably the fastest fighter ever built (although it could not safely sustain speeds higher than Mach 2.8), was designed to counter the American Valkyire bomber, a Mach 3+ wonder that was never mass-produced at full efficiency. 

The subsequent advent of ballistic missiles (and anti-ballistic missiles) greatly reduced the need for high-speed strategic bombers and high-speed fighter-interceptors designed to counter them. On the other hand, fighter-bombers have also become high-speed and can be used in dual roles when necessary. Especially in the bomber role, high speed was deemed necessary for maneuvers to avoid fighters and/or air-to-air missiles. 

Vietnam Example

For example, during the air battles in Vietnam, fighter aircraft such as the F-4 and F-105 adopted the tactic of disposing of their excess fuel (external fuel tanks) and moving rapidly away from the area when a threat appeared against them, thus allowing more aircraft to survive without being shot down. While this undoubtedly resulted in the inability of the F-4 and F-105 to carry out their bombing missions, the 'evasive speed' used was very effective in evading the MiG-21, which was emerging as a highly skilled fighter aircraft at the time. An interceptor with an extremely short range like the MiG-21 had nothing to do against this evasive maneuver. 

However, the main threat to fighter aircraft at the time came from ground-to-air missiles, SAMs. SAMs are still the main threat to modern fighters on the battlefield. However, it has become possible to neutralize these threats by locating SAMs in advance using various intelligence aircraft, suppressing SAMs with defensive suppression (wild weasel aircraft) mission arms, or using technological capabilities (Electronic Countermeasures/low visibility/high anti-radiation missiles (HARM)). Therefore, for Air Forces with these additional capabilities, the speed performance of the fighter aircraft in their inventory has almost ceased to be a necessity.

F-16: The Fighter Aircraft That Gets Fatter and Slower

The F-16, which made its maiden flight in 1974, was initially a successful interceptor, interceptor and dogfight fighter capable of reaching over Mach 2, but over time, it has 'slowed down its speed!' The decrease in the speed of the F-16 is an important factor that supports the view I am trying to reflect in this article. The F-16, which stands out as one of the rare multi-role aircraft that can successfully perform almost all missions in the spectrum of air operations, was a sleek and lightweight 'Mach 2+' aircraft, but now, as with the F-35, it has faced a design transformation that considers flying at 1.6 Mach as sufficient. In other words, the F-16, a multi-role tactical fighter, has slowed down over time. 

According to some, the F-16 has actually gotten heavier. Even the conformal tanks added to the F-16 Viper can be seen as an indicator of this. In order to fulfill the new roles expected of them, F-16s have had to carry more and more equipment. Each new capability added has made the aircraft heavier. In this case, the role of establishing air superiority, which was expected from a conventional F-16, started to take a back seat. The new F-16s have been considered more suited for tactical bombing missions or close air support, isolation, battlefield air interdiction, armed reconnaissance, and support of surface warfare, rather than intercept missions. Instead of 'slim' F-16s, 'fat' F-16s have become preferred as a result of modernizations. 

The F-16s, which have become significantly "fatter" and therefore slower, have shown that they are ready to give up the advantage of high kinetic energy they previously had. Instead, with the high-tech capabilities and new air-to-air missiles, the aircraft has evolved into a mode of use that will substitute or eliminate the reduction in its kinetic capability. Thus, it was able to continue to serve as an aircraft that can easily compensate for what it loses in speed and maintain its advanced fighter-interceptor capabilities. Even today, the F-16, which is seen as a cost-effective and optimized war machine as a multi-role, highly capable aircraft due to its low flight hour cost, is still a modern aircraft that continues to be used by the Air Forces of most countries all over the world.

Multi-Rolling Triggers Low Speed Tendency in Airframes

As a result, instead of a single dedicated mission for the majority of newly produced jets, it has been adopted as a general understanding that fighter jets are designed to fulfill multiple roles as a product of a conscious preference by utilizing the high technology available. In this respect, the TF-23 Kaan has also been designed in line with this trend. We can even expect the Hürjet, which is designed as a jet trainer aircraft, to serve in tactical bombardment missions such as close air support, in addition to its primary role as a "trainer aircraft". This is because the production flexibility of jets now allows us to design multi-role designs. With new capabilities added to every platform produced, we can perform new missions. For example, we can expect an Akinci UAV to launch an air-to-air missile, because technology provides us with all the capabilities to enable UAVs to do so. I believe that this approach will continue to exist for some time as a trend adopted as an extension of the understanding of multi-role missions for all air vehicles. The point I want to emphasize here is that after even a low-speed UAV like Akıncı can launch air-to-air missiles with high kinetic energy, the tactical superiority and kinetic requirements that would require fighter jets to fly at several mach speeds do not seem to make sense for today's air wars.

At the same time, the era of hypersonic missiles and hypersonic vehicles that can reach their targets at over Mach 5 has begun. While the quest for hypersonic speeds in fighter jets is almost non-existent, achieving hypersonic speeds in air-to-ground missiles is seen as a necessity. I believe that air-to-air and air-to-ground missiles whose kinetic energy will support access to hypersonic speeds, and even defensive pressure missiles such as HARM, will be the capabilities that every Air Force will want to add to its inventory in the near future. I expect the capability development activities in the aviation and space industries to be shaped according to these requirements.

Today, the most prominent fighter jet in every aspect is the F-35. At least I am one of those who think so. If we think of it as an airplane with only low stealth capability and no other features, we would probably be wrong. The F-35's data connectivity, networked warfare, electronic warfare, radar and targeting capabilities turn these aircraft into lethal machines. Flying in a closed information network, the F-35s are designed to "talk" to each other without pilot intervention, effortlessly providing each pilot with the best possible situational awareness. For example, when an F-35 aircraft is en route to its assigned target or target area, it may detect an unanticipated mobile SAM threat along its route. This vitally valuable intelligence information is immediately transmitted to other F-35s in the air, and they can use the data transmitted from this first aircraft to update their mission profiles and, if necessary, fly alternative routes. In this way, the threat cannot see themselves and it is easier than before to drop bombs on the target without injury. When we combine this data sharing capability with low visibility and other capabilities, there is almost no need for the F-35 to fly at several mach speeds. 

Conclusion

As a result, thanks to advancing military technologies, today, compared to half a century ago, high speed, and therefore high kinetic energy, is no longer a primary operational requirement for aircraft. Speed has become a less important factor. From the 1950s to the early 70s, the expectation from technology in air warfare was that airframes should be built to support high-performance flights. Today, however, sufficiently mature and optimized airframes capable of carrying high-tech products and capabilities are considered more than sufficient. In short, airframes have fallen to the background, and priority has been given to the acquisition of high technological capabilities that airframes can carry. I observe that Turkish aviation and space technology, which is developing with each passing day, is structured in line with this trend, and that we are moving in the right direction.