F-15 vs F-16
Posted by picard578 on December 11, 2015
F-15 and F-16 are two fighters that came out of programmes started after the Vietnam war demonstrated clear inadequacy of BVR-only designs then in service. When it became obvious that high agility is a necessary characteristic of modern fighter aircraft, F-15 project was revamped in order to give it better agility. LWF project was also started, and resulted in F-16 and F-18. F-16 was designed around John Boyd’s energy maneuverability theories, with low drag and high sustained turn rate. However, USAF did not want a dedicated dogfighter, especially since it could steal light from high-cost F-15; as a result, they turned F-16 into a multirole platform despite it being far less suited for the role than the F-15 (which was later acknowledged with the F-15E). This led to weight increases and loss of maneuverability. Currently, main variants in service are F-15C and F-16C, and these two will be compared by default, unless noted otherwise.
Impact on pilot’s skill
Most important factors in fighter design are ones that directly affect pilot: sortie rate / maintenance downtime, operating cost, user interface and reliability. Good enough pilot will compensate for aircraft’s weaknesses and focus on strengths, and even if aircraft is inferior across the board, he will be able to beat the opponent through tactics. How important training is was shown clearly in Vietnam: early on, USAFs F-4s achieved negative 2:1 exchange ratios against NVAF MiG-19 and MiG-21. Once USAF put some effort into pilot training, they started regularly achieving positive 2:1 exchange ratios. This is despite the fact that in dogfight, angles fighter (MiG) has no inherent advantage over the energy fighter (F-4) – or the opposite. In fact, MiGs had advantage in Vietnam due to smaller size and less smoky engines.
F-15 can fly 1,1 hour every day. Fuel consumption is 2.722 kg/h cruise, 9.072 kg/h at dry thrust and 72.575 kg/h in afterburner. Direct operating cost per hour of flight is 19.000 USD. F-16 can fly 1,2 hours every day. Fuel consumption is 5.610 kg/h dry and 30.336 kg/h in afterburner. Direct operating cost per hour of flight is 7.000 USD.
It is necessary for pilots to fly at least 30 hours per month. At 33 and 36 hours per month, respectively, both F-15 and F-16 are just above the limit. Direct operating cost will be 627.000 USD for F-15 and 252.000 USD for F-16. Overall, two F-16s can be operated for the price of the single F-15, with funds to spare. However, F-16 pilots are seriously disadvantaged when compared to F-15A-D ones due to having to incorporate air-to-ground training in addition to air-to-air training. This disadvantage is lessened by the fact that the F-16 is, based on pilots’ comments, significantly easier to fly.
Since neither aircraft has internal IRST, in most cases they are incapable of reliably surprising the opponent (in standard configuration, at least). Both aircraft typically use RF MAWS and RWRs, providing spherical coverage. F-15s canopy provides 360* horizontal and 196* vertical visibility, including 16* over the nose, 0* over the tail and a maximum of 42* over the side. F-16 has 360* horizontal and 195* vertical visibility, including 15* over the nose, 0* over the tail and 30* over the side visibility.
Neither aircraft has an internal IRST as part of the standard configuration, though USAF has unveiled plans to (finally) equip F-15C with internal IRST. No such plans currently exist for F-16C. F-15Cs AN/APG-63v3 AESA has detection range of 144-185 km vs 1m2 target. F-16C has AN/APG-68 radar with 70 km vs 1m2 target and 120* coverage, though one of newer versions achieves 93 km vs 1m2 target.
Overall, neither has significant advantage in situational awareness at beyond visual range as radar signals will be detected long before radar itself detects the aircraft. Within visual range, F-15 has advantage in maximum cockpit visibility, but F-16 has less framing.
Stealth can be divided into several areas: visual, radar and IR. Visual stealth refers to how easy is to to see the aircraft with Mk.I eyeball. Radar stealth can refer to two things: aircraft’s radar cross section (RCS), and aircraft’s radar emissions (EMCON). IR stealth refers to aircraft’s IR signature.
In terms of visual signature, F-16 is much smaller and thus harder to notice. Its plainview area is cca 500 ft2, compared to F-15s 1.000 ft2. Typical cruise speed for both is around Mach 0,8, but combat cruise speed is at Mach 0,9-0,95. F-16 is likely to have advantage in combat cruise speed due to less draggy single-engined configuration.
In terms of radar signature, F-15C has RCS of 15 m2, while F-16C has RCS of 1,2 m2 when clean. As noted before, F-15Cs radar achieves 144-185 km range vs 1 m2 target, while F-16s radar achieves 70-93 km range vs 1 m2 target. Consequently, F-15 will detect F-16 at 151-194 km, while F-16 will detect F-15 at 138-183 km. If jamming is used, F-15 will be able to attack F-16 from 0-37 km, while F-16 will be able to attack F-15 from 0-35 km. However, both aircraft will give away their presence at several hundred kilometers if they use radar for initial detection, and actual radar signature will be significantly higher. With weapons, RCS will be higher (20 m2 for F-15, 5 m2 for F-16?), so F-15 will detect F-16 at 215-277 km, while F-16 will detect F-15 at 148-197 km.
Neither aircraft has internal IRST as a standard, but both can be equipped with external IR pods, and there are variants equipped with internal IRST. However, IR signature is still significant against foreign IRST-equipped fighters. In this area, F-15 is disadvantaged, producing 11.793 kgf dry and 18.144 kgf wet, compared to F-16s 7.530 kgf dry and 12.700 kgf wet. F-16 also has marginally higher cruise speed, and may achieve Mach 1,1 with two wingtip missiles. This slightly increases difference in IR signature. When supersonic, F-16s smaller wing span will result in smaller shock cone, and IR signature from afterburner will be smaller, though still significant. Note that both size and temperature are important: while at low altitude atmospheric absorption and clutter mean that it is easier to notice hotspots, at high altitude lack of both atmosphere and clutter means that target size and sensor’s resolution play important role as well.
As noted before, neither aircraft is realistically capable of supercruise, though F-16 should have slight advantage in maximum cruise speed. At maximum dry thrust, and assuming that both aircraft can spend 30% of internal fuel, F-15 can cruise for 8,93 minutes while F-16 can cruise for 10,19 minutes.
Maximum combat radius on internal fuel is 1.000 km for the F-15 and 925 km for the F-16. This is not surprising since F-15C has both higher fuel fraction (0,29 vs 0,27) and higher internal fuel load (4.500 vs 3.175 kg).
F-15C has 25,5 deg/s instantaneous turn rate and 13,1 deg/s sustained turn rate (other info gives 21 and 15-17 deg/s), compared to F-16Cs 26 deg/s instantaneous and 18 deg/s sustained. Since two degrees per second turn rate difference allows pilot to dominate adversary in dogfight, it is clear that F-15 is seriously outmatched in sustained turns. F-16 also has significantly faster pitch onset rate due to aerodynamically unstable design. Roll onset rate will be higher for the F-16 due to smaller wing span, presence of LERX vortices and single-engined configuration.
At 40.000 ft, F-15 can accelerate from Mach 0,8 to Mach 1,2 in 52 seconds, compared to 44 seconds for F-16. F-15 can climb to 30.000 ft in 60 seconds, and initial climb rate is 254 m/s. F-16Cs initial climb rate is also 254 m/s. As it can be seen, F-16 has slightly superior energy management abilities, allowing it to gradually gain an advantage over the F-15 during dogfight. It should be noted that aerodynamically clean configuration for F-16 includes two wingtip missiles, slightly improving its dogfight performance relative to the F-15. Further, span loading is 1.205 kg/m for F-15 and 1.098 kg/m for F-16, increasing latter’s advantage in lift/drag ratio during the turn.
(Note that the best way to escape either missile or gun shot is instantaneous turn in order to put the attacker at 3/9 o’clock followed by acceleration, and if necessary another turn. Sustained turns do not have much place in dogfight. In a multi-ship dogfight, no turn should be followed for more than 90 degrees).
F-15s higher wing sweep (45* vs 40*) also means slower drag rise with increased speed. Nose-to-wingtip angle is 65* for both F-15 and F-16, so in that area there is no difference. This, combined with variable intakes, improves F-15s supersonic maneuvering ability when compared to the F-16. F-16s lower wing sweep results in extended transonic region and much faster supersonic drag rise with Mach number.
During supersonic flight, aircraft will become more stable. Since F-15 is naturally aerodynamically stable, and F-16 is aerodynamically unstable, this means that F-16 may have advantage in lift-to-drag ratio at low supersonic speeds due to its tail providing upload, reducing angle of attack necessary to maintain level flight.
Both aircrafts’ primary missiles are AIM-120 for beyond visual range engagement and AIM-9X for within visual range engagement. AIM-120D is a RF BVR missile with 180 km maximum aerodynamic range. It has 40 g maneuvering capability at Mach 4. AIM-9X is an IR missile with 26-42 km maximum aerodynamic range and 50 g maneuvering capability at Mach 2,7.
Both aircraft also have the same gun. F-15 has standard loadout of 8,6 gun bursts, 4 AIM-9 and 4 BVRAAM, giving it a total of 3,16 onboard kills. F-16 has standard loadout of 4,7 gun bursts, 2 AIM-9 and 4 BVRAAM, giving it a total of 1,84 onboard kills. However, it can equip two additional BVRAAM, giving it 2,00 kills. As it can be seen, F-15 has advantage in number of onboard kills; otherwise, weapons used are identical. Both aircraft can use AIM-9X Block III as an IR BVRAAM, but they lack IRST to fully capitalize on that advantage.
Numbers in the air
F-15 allows 33 hours per month in the air, while F-16 allows 36 hours per month in the air. Direct operating cost is 627.000 USD for F-15 and 252.000 USD for F-16. If two F-16s are used, they will allow 72 hours per month in the air for 504.000 USD, a 2,18:1 advantage.
If initial costs are compared, F-15C costs 130 million USD compared to 70 million USD for F-16C, giving latter 1,85:1 numerical advantage. When combined with sortie rate advantage, F-16 has a clear 2:1 numerical advantage over F-15. F-16s fuel consumption is about half of the F-15s, which means that there will be no difference in logistical tail as far as fuel and engine spares are concerned.
Response to attacks
Neither aircraft is designed for operation from road bases or dirt strips. If forced, F-16 has significant advantage in road base operations due to smaller size, lower maintenance requirements and lower fuel consumption. As neither aircraft can supercruise with weapons load, there is not likely to be any significant difference in response time once in the air.
Engagement kill chain performance
Kill chain consists of following steps:
- detection capability
- identification capability
- cruise speed
- maximum speed / mach on entry
- altitude on entry
- lock on / firing solution range
- missile seeker diversity
- endgame countermeasures (inbuilt, towed, disposable; jammers, decoys, chaff, flares)
- defeat the missile / disengage
- airframe agility
- sensors coverage
- mach on egress / fuel reserves on afterburner
- BVR missile seeker diversity
- BVR missile agility
- BVR missile warhead lethality
- WVR missile agility
- WVR missile warhead lethality
- gun lethality
Detection range depends on target signatures and sensors used. With radar, F-15 will detect F-16 at 215-277 km, while F-16 will detect F-15 at 148-197 km. However, radar is an active sensor. Signal has to be sent out, reflected from the target and received. Even assuming that target is a flat plate and that entirety of the signal reaches it, radar will get back 1/16th of the signal – at best. However, RCS comparison shows automobile to have an RCS of 100 m2 (likely from the side; from the front, 25-50 m2 value can be expected). Consequently, radar will receive at best 1/200th of the signal sent out, which will give significant advantage in detection range to RWR. Since both fighters are likely to have RWR, radar is not likely to be used.
If radar is not used, both fighters will – in basic variants at least – have to rely on Mk.I eyeball. As noted before, F-16s plainview area is cca 500 ft2, compared to F-15s 1.000 ft2. This means that F-16 will be noticed at distance of 8 nautic miles, while F-16 will be noticed at 11,4 nautic miles. From front, detection distance will be smaller but difference will be of similar, or greater, magnitude. However, in order to carry out identification, fighters will have to come within 400-800 meters; here again F-16 has the advantage due to smaller size and better cockpit visibility. Radar-based NCTR is very unreliable (30% identification reliability at best) and can be disabled by jamming or by target maneuvering. Because of this, 82% of the enemy aircraft engaged during Desert Storm had to be identified with help of AWACS, which will not be avaliable against a competent opponents as comlinks will be jammed, and AWACS aircraft will not survive for long in a proper war.
Both aircraft have cruise speed of around Mach 0,9 with air-to-air load. However, F-15 has top speed of Mach 2,5 while F-16 has top speed of Mach 2,0, limited by air intake. F-15 also has service ceiling of 65.000 ft, while F-16s service ceiling is 50.000 ft. Peak altitude is cca 100.000 ft for F-15 and somewhere above 70.000 ft for F-16. Dash speed and altitude advantage will allow F-15 significant effective missile range advantage in a BVR engagement.
As shown before, F-15 will detect F-16 at 151-194 km, while F-16 will detect F-15 at 138-183 km. This means that F-15 will be able to attack F-16 from 120-155 km, while F-16 will be able to attack F-15 from 110-146 km. If jamming is used, F-15 will be able to attack F-16 from 0-37 km, while F-16 will be able to attack F-15 from 0-35 km. Both aircraft will receive IR BVRAAM once AIM-9X Block III enters service.
Both aircraft also have AIM-120D, with 180 km maximum aerodynamic range. However, missile range from the rear is 1/4 of stated missile range and effective range is 1/5 of aerodynamic range, effective missile range for BVR engagement will be 9-36 km. In other words, both aircraft will be able to utilize AIM-120Ds maximum effective range in spite of jamming.
Defeat the missile / disengage
Once warned of a missile launch, first reaction is to properly position the aircraft for evasion. At beyond visual range, it is oftentimes enough to turn the aircraft away from the missile. At shorter ranges (near-visual and visual range), pilot has to quickly position the missile to the aircraft’s 3 or 9 o’clock and then turn into the missile once close enough. Both of these require high instantaneous turn capability, as well as acceleration / climb to recover lost energy. F-15C has 25,5 deg/s instantaneous turn rate, 16 deg/s sustained turn rate and 52 second acceleration from Mach 0,8 to 1,2. F-16 has 26 deg/s instantaneous turn rate, 18 deg/s sustained turn rate and 44 second acceleration from Mach 0,8 to 1,2. Both have identical initial climb rate at 254 m/s, however F-16 has significantly superior transient performance due to aerodynamically unstable design, single-engined configuration and smaller wing span.
Both F-15 and F-16 has 360* coverage with missile warners, and radars which cover 120* in front of the aircraft. Consequently, when missiles are fired neither aircraft can initiate proper evasive maneuvers until missiles acquire the target themselves.
Fuel reserves for afterburner are also important. Assuming that both aircraft have 40% of the fuel avaliable for maneuvers, F-15 has enough fuel for 1,49 minutes of maximum afterburner while F-16 has enough fuel for 2,51 minutes of maximum afterburner. For more exact comparison I will assume 360* corner-speed sustained turn (or, rather, four 90* turns) followed by acceleration equivalent in time to M 0,8 – 1,2 acceleration. F-15 will use 22,5 seconds for turn and 52 seconds for acceleration, for a total of 74,5 seconds of maximum afterburner and 1,2 maneuvers. F-16 will use 20 seconds for turn and 44 seconds for acceleration, for a total of 64 seconds of maximum afterburner and 2,35 maneuvers. If 90* instantaneous turns are used, F-15 will need maybe 16 seconds for turns and 70 seconds of afterburner in total, for 1,04 maneuvers. F-16 will need maybe 15 seconds for turns and 59 seconds of afterburner in total, for 2,55 maneuvers. If equivalent of 10.000 m climb at maximum climb rate is used instead of acceleration, F-15 will need 56,9 seconds, giving it 1,57 maneuvers. F-16 will need 54,4 seconds, giving it 2,77 maneuvers. As it can be seen, F-16 has significantly higher combat endurance despite lower fuel fraction and lower total fuel load. This can be explained by F-16 having advantage of being unstable single-engined aircraft.
In terms of countermeasures, most modern versions of both aircraft can be expected to have chaff, flares and internal DRFM jammer. F-16s lower radar and IR signatures make usage of countermeasures more beneficial, though this is somewhat countered by the fact that smaller size and less engine power also means less power avaliable for jamming. Both arcraft, in variants equipped with AESA radar, can use radar for jamming. Radar only covers 120* forward cone and to do so it has to sacrifice frequency agility, making it vulnerable to anti-radiation missiles.
In terms of agility, AIM-120D can both pull 40 g at Mach 4, giving maximum turn rate of 18,54 deg/s. As instantaneous turn rate is 25,5 deg/s for F-15 and 26 deg/s for F-16, it can be seen that both aircraft can easily evade it. AIM-9X can pull 60 g at Mach 2,7, for 41 deg/s ITR, which neither aircraft has a good chance of evading. That being said, kill is by nomeans certain, as in some conditions missile may need to have at least as much as twice the aircraft’s turn rate to hit.
If both aircraft are flying at Mach 0,9, 9 g limit results in 18,55 deg/s turn rate. Consequently, neither aircraft will be capable of defeating any of the missiles within their no-escape zones, barring less-than-ideal launch parameters for missiles.
In terms of gun lethality, both aircraft use M61A1. M61A1 fires 98 g projectile with 11% HEI content at 1.036 m/s muzzle velocity and crossectional density of 31,2 g/cm2, which gives them equal gun effectiveness, but far inferior to some of the foreign fighters.
Ground survivability includes possibility of camouflage and ability to operate from road bases. Latter includes STOL capability, wingspan limits, fuel consumption and ease of maintenance considerations. Wingspan should not be greater than 8,74 meters.
F-15 can take off in 274 m (?) and land in 1.067 m without parachute, while F-16 can take off in 457 m and land in 914 m. Wingspan is 13,05 m for F-15 and 9,96 m for F-16, giving major advantage to the latter but placing them both well outside ideal wing span. F-15 has fuel consumption of 2.722 kg/h cruise, 9.072 kg/h at dry thrust and 72.575 kg/h in afterburner, while F-16s fuel consumption is 5.610 kg/h dry and 30.336 kg/h in afterburner.
Overall, F-16 has advantage in ground survivability due to smaller wing span. Lower fuel consumption and maintenance requirements also mean smaller logistical footprint and thus less vulnerable supply tail.
Overall, F-16 is significantly superior to F-15 in most important areas, such as pilot training, logistics and numbers. Technical characteristics are more or less similar, with F-15 having significant advantage in beyond visual range combat due to higher top speed and service ceilling, longer detection range. F-16 has even greater advantage in visual-range combat due to smaller visual signature, superior maneuvering ability and superior combat endurance.