Comparative Analysis: Aircraft Military Effectiveness
Key notes
An introduction to military aircraft systems: An overview of the metrics we will use to evaluate and compare military aircraft systems
A comparison of the B-2 and the F-16: Using those metrics we develop a comparative study to further our understanding of these systems and build evaluative tools
Evaluating context-dependent qualities: Building our understanding of the metrics into a deeper understanding of the systems and the contexts each thrives in
Introduction
Military grade aircraft comprise a key element of any modern military force structure. They can fill multiple roles and provide assistance in reconnaissance, logistics, or ordinance delivery. Aircraft design is a process of balancing four principles, those being lift, thrust, drag, and weight. Each of these may be increased or decreased by the physical characteristics of the aircraft, as well as by the density of the medium it flies through. Lift is created by the wings of the aircraft, specifically the wing area combined with its shape and angle of attack. Angle of attack refers to the angle of the wing as it moves forward into the medium, and is also a key determinant in how much drag the aircraft produces. Drag comes in two forms, induced and parasitic. Induced drag is drag created as the price for creating lift, while parasitic drag is drag that comes without the benefit of creating lift. Thrust is produced by the engine and provides motive force. Controlling an aircraft is difficult due to its operational area comprising three distinct dimensions. Due to that an aircraft in flight may roll to some degree along its flight axis, it may yaw to the left or right, or it may pitch up or down. Since aircraft operate along three axes, turning is a complex process involving careful control of the air moving over the wing and an often rear mounted rudder to bank onto a different course.
The aircraft we will examine are the F-16c and the B-2. The aspect ratio of the F-16 is 3.2[1] while the aspect ratio of the B-2 is 5.78.[2] The B-2 bomber has an aspect ratio almost double that of the F-16 which provides the B-2 greater lift and less drag when compared to the F-16 at the cost of a worse turning radius.[1][2]
Design
The F-16 has a length of 15 meters and the B-2 has a length of 20 meters. Both aircraft have similar heights, both around 5 meters.
The F-16 has a wing area of 27.87 meters squared while the B-2 has a wing area of 464.5 meters squared. This difference in wing area gives the B-2 greater lift and the ability to fly in the lower oxygen environments that exist at higher altitudes at the cost of higher drag than the lower wing area of the F-16.[1][2]
The F-16 has a weight of 8,433 kilograms empty and the B-2 has a weight of 49,900 kilograms empty. The F-16 has a weapon load of 7,226 kg compared to the B-2’s max weapon load of 18,14 kilograms. The F-16 has a max fuel load of 3,249 kilograms and the B-2 has a max fuel load of 90,720 kilograms. The max takeoff weight of an F-16 is 22,679 kilograms while the B-2 has a max takeoff weight of 168,433 kilograms. The max takeoff weight of a B-2 is about equal to its weight while empty, plus its maximum fuel load, plus its max weapons load. The F-16 has a maximum takeoff weight in excess of its weight while empty plus max fuel load plus max weapons load. The discrepancy between the maximum takeoff weight and the calculated maximal capacity weight in the F-16 is due to the presence of external fuel tanks on the F-16 that are not on the B-2. Such tanks add fuel supply that is not internal to the aircraft at the cost of creating parasitic drag.[1][2]
The F-16 has a wing loading ratio of 486.8 kilograms per square meter while the B-2 has a wing loading ratio of 311.5 kilograms per square meter. Neither of these matches the max takeoff weight/wing area. A lower wing loading ratio has the generic benefit of adding agility.
The F-16 produces a thrust to weight ratio of 1.1, its thrust is greater in than its weight. The B-2 has a T/W ratio of 0.205, its thrust is 1/5th of its weight pound per pound. It is unclear from the specs if the T/W ratio is drawn from the wet thrust or the dry thrust, however the dry thrust of the B-2 is given and dividing the dry thrust by any weight given does not produce the ratio thus we may assume that the numerator of the ratio is supplied by the wet thrust.
The F-16 can go at speeds in excess of Mach 2, the B-2 can only operate at subsonic speeds. From the given specs it is impossible to tell whether this represents Max Speed using afterburn or Cruise Speed.[1][2]
Combat Use
The F-16 has a combat radius of between 1250 and 1600 km while the B-2 has a combat radius of 12,223 km. The F-16 provides no flight profile data and the range of combat radii provided may be due to the fact it may fly multiple patterns or it may represent a combat radius based on afterburn use. The B-2 is provided a flight pattern of HHH, meaning it operates only on missions that allow it to be at high altitude the entire flight.[1][2]
The F-16 provides no specified takeoff or landing runway, nor a ceiling. The B-2 requires a landing runway of 1981 meters and has a ceiling of 50,000 feet.
The F-16 has a crew of one where the B-2 has a crew of 2. The F-16 has a Radar Cross Section of 1.2 and the B-2 has a Radar Cross Section of essentially zero.
The F-16 has a flyaway cost of 27.9 million and the B-2 has a cost of nearly 2 billion. Lastly the F-16 has an IOC of 1978 and the B-2 of 1997. Both the F-16 and the B-2 have swept wings, and the F-16 has an incredibly obvious streamlined design while the B-2 does not look streamlined to my layman eyes.[1][2]
Due to the F-16 having a much greater thrust to weight ratio and better streamlining it has a much higher maximum speed as well as a much higher cruise speed. This speed would be an asset in the area of mobility and survivability.[1]
The B-2 has a much greater Combat radius and we can assume a much greater Maximum range. This is provided through its huge fuel capacity as well as its flight profile. By taking on only missions that are at steady altitude very high up, once it reaches altitude it can fly tremendous distances with minimal fuel usage due to the low drag created at those altitudes and afforded by its high aspect ratio. We can assume it has greater maximum range and greater unfueled range as well.[2]
The F-16 has better acceleration due to its more streamlined design and higher thrust to weight ratio.
The F-16 also has a much better climb rate due to its high thrust to weight ratio. Roll rate is unclear from the spec sheet, however it was noted in class that the B-2 does not have a rear rudder and in order to turn it uses eleverons which are far less efficient than other methods. Also true is that the higher aspect ratio of the B-2 reduces its roll rate. Due to these facts it is safe to say the F-16 has greater agility than the B-2.[1][2]
Detectability
It is difficult to get a sense of how trafficable each airplane is. Since the B-2 operates at high altitudes it is safe to assume it can operate in all weather as once it is at altitude it is likely above any cloud cover.
The B-2 is certainly much more stealthy than the F-16 since it is undetectable by radar and flys missions at very high altitudes where detection even by augmented EO and IR detection methods is likely very difficult.[2]
The F-16 having a much higher speed and maneuverability lends it survivability over the B-2 against an enemy attack, however the B-2 seems to have the strategy of avoiding attack entirely and thus this comparison comes down to how effective this strategy of avoiding detection is versus the survivability gained by the F-16 being able to dodge attacks. For instance, if the F-16 is attacked on 20% of flights and can avoid attacks 50% of the time, it avoids damage on 90% of all flights. If the B-2 bomber avoids detection of 95% of all flights, it has greater survivability. However we are not provided statistics granular enough to say with any certainty which aircraft has the greater survivability but my instinct is that the B-2 is more survivable because it has such extreme stealth and cost.[1][2]
Weapon Specs
We are given no information about weapon load from the spec sheet beyond that the B-2 is designated as a bomber and the F-16 is designated as a fighter. Since the F-16 has external fuel tanks available it seems likely to have hard points on which to mount a variety of ordinance if it eschews those external fuel tanks. Given that the F-16 is a fighter with hard points that may mount a variety of weapons it seems very likely that it may also have the option to equip some kind of radar system whether to assist in weapons guidance or to assist in threat detection. The B-2, given its commitment to a low radar cross-section, would likely not want external payload and thus would store all its bombs internally. From this we can deduce it needs some sort of sensor to inform it of its location relative to the target. From its commitment to low radar cross-section we assume it lacks effective radar of its own because mounting a radar onto a plane with zero radar cross-section likely gives it radar cross-section.[1]
The B-2 has a cost orders of magnitude greater than the F-16, and also a later IOC. If looking only at that statistic, one may be tempted to assume that it can do everything the F-16 can do and more. However, the B-2’s budget has created a precision machine with a highly specified use case, as demonstrated by its flight path and stealth properties. This points to the idea that even at high costs, engineers cannot get around these trade-off relationships. Creating a perfect general purpose aircraft at a budget that high would have certainly been feasible, but the designers of the B-2 have instead eschewed any spec that was deemed unnecessary in order to really maximize stealth, distance, and high aerial bombardment capability.[2]
The F-16, despite its lower cost and more dated IOC, has key advantages over the B-2. These being in the areas of speed and mobility. Its engineers focused their comparatively much smaller budget on the specs of high mobility, high speed, and more customizable kit through the hard points. Presumably this was done because the F-16, since it is detectable by radar systems, would have to deal with incoming anti-air defenses which could include missiles or rockets fired from the ground, air to air systems, or static artillery shells. For that purpose, higher mobility and higher speed are requisites if a pilot wants to establish air superiority and make it back to base, and greater customizability grants it effectiveness against a wide variety of targets in the field.[1]
Implications
These aircrafts are incredibly different machines with incredibly divergent specifications which point to their different use cases and also towards a military strategy using both in tandem to achieve air superiority over a target area. It is instructive that the F-16 has a much lower cost than the B-2 despite outperforming the B-2 in certain areas. This illustrates not only that design trade-offs exist no matter the budget, but also a budgeting priority of the military services in that the F-16 is likely to be detected and shot at much more often than the B-2. As a result of this, the B-2 can justify a higher cost since it is less likely to need replacement. This aspect of the budgeting process represents a moral trade-off. The pilot of the F-16 is more likely to need survivability than the pilot of the B-2, but since his rig costs less he is less likely to get it except through his abilities.
References
Northrop Corp. “B2 Division.” In Jane’s All the World’s Aircraft, 1991 ed. London: Jane’s Information Group, 1991.
Lockheed Martin “USA Aircraft.” In Jane’s All the World’s Aircraft, 2001 ed. London: Jane’s Information Group, 1991.
