Compared Air Combat Performances analysis Mig-21 versus F-5E

Transcription

1 Compared Air Combat Performances analysis Mig-21 versus F-5E LICENSE: This document has been created by J.M. LANGERON / TOPOLO, ( All the values used to model the aircraft behavior have been computed by him, like all performance charts presented here, based on data provided by the people mentioned in the CREDITS section. If you want to use these data, or part of it, please contact the author by personal message to TOPOLO on check-six forum: ( CREDITS: It has been possible to build this document only due to the collection of many data regarding Mig-21 and F-5E performances, their use in dedicated conflict (Ogaden war) and many other details. The group involved in this project has also spent a lot of time in reviewing this document and those mentioned in the Bibliography section. I want to thanks particularly Tomislav MESARIC for his Mig-21 knowledge and data, Chuck CANYON for the F-5E, Tom COOPER (ACIG.org) for his huge knowledge on military aerospace in general, the history of these aircraft in particular, and the fact that he build the working group. A. Introduction The aim of this document is to analyze the performances, mainly turning, climbing and acceleration, (roll rate is not part of the scope due to complete lack of objective data) of the two aircraft families to identify forces and weakness of each in close air combat scenario. It will not be taken into account at all of weapon system capabilities, nor of aircrew training, tactics or strategy, but only focus on airframe and engine. The two aircraft families will be represented by particular sub versions. For the Mig-21 the choice has been mainly driven by the idea to covers the complete performances range of the family and the available documentation. Performance charts of ex-yugoslavian L-15 and L-17 enable the identification of the flight behavior of both (izd.96a) and (izd.75a). The major role of the (izd.96f) also leads to build a dedicated flight model for this version, even if the complete performance manual has not been found for it. For the F-5, the Tiger-II F5-E-3 has been chosen because it has the best performance of the family (its better instantaneous turn rate being the result of the efficiency of its auto-flaps device). A single sub version of the Northrop aircraft has been selected to limit the number of comparison to document (and also due to the quite homogeneous performance across the family compared to the Mig-21 very wide range) All documents describing the individual aircraft performances and how they have been built are listed in the Bibliography section of this document. B. Methodology description. Aircraft configuration definition. For the three first sections of the document, the aircraft configurations have been defined with the same criteria: loading reduced to two infra-red guided short range missiles and full gun ammo, all pylons that cannot be jettisoned and that are usually required for air combat mission take-off, fuel quantity set to half of the internal capacity. These configurations are named Combat configuration For the last section, related to an historical scenario (Ogaden war), both aircraft configurations have been built from our knowledge of the take-off configuration and estimation of the flight path, the fuel consumption, and the jettison strategy. In all cases, these choices lead to the definition of the gross weight and the drag index value used to compute performances. Caution: definition of drag index is very different in US and Soviet performance manuals so do not be surprised by the value differences. combat configuration. Aircraft loaded with 5% of usable internal fuel, Center Line pylon (but no CL Tank), 2 R-3S missiles with their pylon under wing. This defines a gross weight of 15,673 lbs (7,1kg) and a Drag Index of 12. Clean Aircraft (no usable fuel) : 5,76 kg 2 gun ammo (Gsh 23) : 75 kg 2 Under-wing pylon : 45 kg 1 Center line pylon : 24 kg 2 Missile rails for R-3S : 41 kg 2 Missile R-3S : 15 kg 5% internal fuel : 1,5 kg This gross weight leads to the following load factor limitation: For lower than.8 : 8. G For greater than.8 : 6. G combat configuration. Aircraft loaded with 5% of usable internal fuel, Center Line pylon (but no CL Tank), 2 R-3S missiles with their pylon under wing. Thursday, March 7, 213 Page - 1

2 This defines a gross weight of 15,673 lbs (7,1kg) and a Drag Index of 12. Clean Aircraft (no usable fuel) : 5,76 kg 2 gun ammo (Gsh 23) : 75 kg 2 Under-wing pylon : 45 kg 1 Center line pylon : 24 kg 2 Missile rails for R-3S : 41 kg 2 Missile R-3S : 15 kg 5% internal fuel : 1,5 kg This gross weight leads to the following load factor limitation: For lower than.8 : 8. G For greater than.8 : 6. G combat configuration. Aircraft loaded with 5% of internal usable fuel, Center Line pylon (but no CL Tank), 2 R-6 missiles with their pylon under wing. This defines a gross weight of 16,46 lbs (7,432 kg) and a Drag Index of 11. Clean Aircraft (no usable fuel) : 6,3 kg Gun ammo (25 rounds) : 95 kg 1 Center line pylon : 24 kg 2 Under-wing pylon : 5 kg 2 Missile rails for R-6 : 7 kg 2 Missile R-6 : 9 kg 5% internal fuel : 1,6 kg This gross weight leads to the following load factor limitation: For lower than.8 : 8. G For greater than.8 : 6. G For Mig-21Bis, the Special-After-Burner will always be used when possible (under 4,m), even if only After-Burner is mentioned. combat configuration. Configuration has been defined according USAF F-5E/F flight manual (T.O. 1F-5E-1 or 1st of August 84 with Change 9 of 15th of November 199) Aircraft loaded with 5% of internal fuel (2,259 lbs), 2 wing tip AIM-9 missiles with their rails. This defines a gross weight of 13,75 lbs and a Drag Index of 18. The load factor limitation is set to 7.33G and does not depend on. Clean Aircraft (no fuel, pilot) : 1,659 lbs Gun ammo : 394 lbs 2 Missiles AIM-9 : 34 lbs 2 Missile rails for AIM-9 : 98 lbs Zero fuel weight : 11,491 lbs Internal fuel (JP-4) : 2,259 lbs Critical performances to be compared. For each altitude, we will compare turning, climbing and acceleration capabilities. Turning Turning capabilities will be measured by following performances: Quickest half turn: Minimum time required to perform a 18 deg turn with maximum G-Load (structural or maximum lift limits). Maximum Sustained Turn Rate: Minimum time required to perform a constant speed 36 deg turn and related radius (maximum sustained turn rate). Minimum Sustained Turn Radius: Minimum turn radius of a constant speed 36 deg turn and required time. WARNING: for Mig-21, two tests need to be performed, in the first one the pilot is assumed to limit the AoA to 28 degrees, according to the black sector limit of his AoA indicator, in the second test, the pilot is assumed to reach and keep the maximum lift AoA. The first test could be considered as representative of an average Mig-21 pilot, when the second is only to be considered for high skilled highly trained pilots. Climbing Non turning climb: both aircraft flying at their maximum constant speed climb rate, starting from same point, what time is required for an altitude gain of 2,ft for the fastest, how many feet above is the other one at this time. Turning climb: both aircrafts engaged in a constant speed, constant G-load (2G at 3,ft, 3G at 15,ft, 4G at 5,ft) turn, which altitude gain after 9 degrees. Acceleration Both aircrafts perform a level flight, starting at same speed (Mach.5 and Mach.9), the performance is the horizontal distance covered after three minutes. Also expressed by the time and distance the fastest can be late and still rejoin its target in less than 3 minutes. C. Medium level combat (15,ft). Turning performances. Quickest half turn At 15,ft the test compares planes on the quickest 18 deg turn. The best half turn start at mach.92 (477 Kts indicated air speed) and end in 11.8s at Mach.43 (214 Kts IAS) with an average turn radius of 2,59ft. The best half turn with AoA limited to max lift start at mach.87 (45 Kts IAS) and end in 13.2s (+2.4s) at Mach.52 (262 Kts IAS) with an average turn radius of 3,168 ft. Graphic comparison in fig1.1 Thursday, March 7, 213 Page - 2

3 Sustained Turn Rate (d/s) Sustained Turn Radius (ft) ; 2,59 max lift; 3,191 max lift; 3,168 max lift; 3,485 AoA<28; 3,656 AoA<28; 3,667 AoA<28; 3,934 ; 11.8 max lift; 13.2 max lift; 13.2 max lift; 14.2 AoA<28; 14.6 AoA<28; 14.2 AoA<28; 15.4 with AoA limited 28 end its half turn in 14.4s (+4.6s) at Mach.68 (347 Kts IAS) with an average turn radius of 3,667 ft. Graphic comparison in fig1.2 Other Mig-21 sub-types performances are described in the following diagrams. The comparative performances of the 4 aircrafts at their maximum sustained turn rate speed are described in the following table and diagram: 15, ft STR Turn Time for at Mach deg/s Radius , , , , And in the appendix section, fig.1.3. Compared to the Mig-21 family, we can see that the advantage still goes to the F-5E, the difference with the or M is significant (3 sec. / 8% for a complete 36 deg turn), when is clearly more (6 sec.) disadvantaged. Time (s) required for half turn The speed range covered by this comparison allows us to say that this criterion (maximum sustained turn rate) defines the hierarchy in the high-speed turning capability (4 Kts IAS). Minimum Sustained Turn Radius Focusing on vs. F-5E3, the following figure show a very small difference between the two planes: 1ft in radius and 1Kts in speed, that cannot be considered as significant. Average half turn radius (ft) 2, 18, 16, It can be seen that all other Mi-21 are slower to perform half turn and do it with a bigger average radius. 14, 12, 1, 8, A deep analysis of the figure 2.1 shows that the has a smaller turn rate at the beginning of the turn mainly because of the load factor limitation: when F-5E can pull 7.33G all along its speed range, is limited to 6G when mach is over.8 (415 Kts IAS), and this limit is reached during more than 6 sec. (half of the half turn). Maximum Sustained Turn Rate If we focus on, the following figure shows that the two planes are equivalent under 32Kts, and F-5E has a positive margin only from 35 to 5Kts, that are the most common turn fight speed, if the Mig pilot can impose a speed lower than 32Kts, he will clear the advantage of its opponent, if both accept a 4Kts turn fight, the F-5E will be advantaged. 6, 4, 2, CAS (Kts) The comparative performances of the 4 aircrafts at their minimum sustained turn radius speed are described in the following table and diagram: 15, ft STR Turn Time for at Mach deg/s Radius , , , , And in the appendix section, fig The speed range covered by this comparison allows us to say that this criterion (maximum sustained turn rate) defines the hierarchy in the low-speed turning capability (15 Kts IAS). The advantage goes to the, then the F-5E, and and last the heavy. Thursday, March 7, 213 Page - 3

4 Climb Rate (ft /s) Climb Rate (ft /s) At 15, ft an F-5E has the quickest first half turn, the best maximum sustained turn rate, and the best turn rate and turn radius at 2Kts or more compared to any Mig-21. Only a can try to take advantage of its smaller minimum turn radius at very low speed (15Kts and less). In general, F-5E pilot would not be in bad position in accepting a dog-fight versus a Mig-21 at this altitude. He has equal or better turn performance than any Mig-21 between mach.6 and.95 (35 to 495 Kts), better than and Mi-21bis and similar to between 15 and 35Kts, he would enter in bad shape only at very low speed against a. So keeping the speed over 2Kts will keep a positive margin. A could also enter such a dogfight versus an F-5E without being disadvantaged, as soon as the speed rmain lower than 3Kts, he can even goes to very low speed (15 Kts) to take advantage of its turn radius but this will not give him a really significant benefit, and this will not be the case for or bis. Climbing performances. Non turning climb. Focusing on vs. F-5E3, the following figure shows that the climb rate of the two planes are equivalent except between 42 and 51Kts, where the F-5 can claim being 3 ft/s faster That means that if the F-5E pilot want to use his climb speed to break a high speed subsonic dogfight (M.9 / 35 Kts indicated) fight and evade in climbing in, he can do it only against a, in a certain way when facing a Mig- 21MF but not when facing a. If we consider the same scenario where the pilot want to evade a low speed dogfight (M.5 / 25 Kts indicated) by climbing at constant speed, the situation is: - The requires 9 s to gain 2,ft, during this time the F-5E will gain only 1,874 ft (126 ft lower) - The requires 9.5 s to gain 2,ft, during this time the F-5E will gain only 1,963 ft (37 ft lower) - The requires 1.2 s to gain 2,ft, more than the F-5E (9.6s). Meaning that 21bis can try to evade a low speed dogfight (IAS < 25 Kts) in front of the F-5, in climbing, but the Mig- 21MF cannot and the will be surpassed. On the other side, an F-5E pilot would not try to evade in climbing at low speed, as this will be successful only when facing an old. So the non-turning climb rate comparison gives a small advantage to the modern variants of the at low speed (IAS < 25Kts), when the high subsonic (M.8-.9 / Kts) case see the F-5E a bit better than the Mig- 21bis and better than the and M. Turning Climb. Focusing on vs. F-5E3, the following figure shows that the F-5 climbs faster in a 3G turn up to 51Kts indicated (up to 6 ft/s faster) CAS (Kts) 2 15 The constant speed climb rate of each aircraft at 15, ft is described in figure 1.5. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed with Full (or Special) After Burner engaged. We can see that the has the best maximum climb rate: 383 ft/s (354 ft/s for the 21MF), and this value is reached at higher speed (mach.9 for F-5E when climb rate remain quite constant between M.8 and M.88 for Mig- 21MF). Mig-21Bis is not far away (366 ft/s at Mach.88 / 455Kts) and one step beyond (337 ft/s at Mach.82 / 425Kts IAS). If all aircraft keep a constant speed corresponding to their best climb rate, the 2,ft gain will require 5.2 seconds for the F-5E. During the same time the gains 1,91ft (9 ft lower), the gains 1,848 ft (152 ft lower), and the gains 1,76 ft (24 ft lower) CAS (Kts) The constant speed, constant 3G climb rate of each aircraft at 15, ft is described in figure 1.6. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed and G-Load to 3. with Full (or Special) After Burner engaged. In a high subsonic (M.9 / 465 Kts indicated) 3G turn, the F- 5E get the best climb rate. The turn rate is the same for all and allows a quarter turn in 16.4 sec (5.48 d/s), during this time, - The F-5E will gain 4,312 ft (263 ft/s) - The will gain 2,876 ft (175 ft/s) and so will be 1,436 ft lower. Thursday, March 7, 213 Page - 4

5 Distance (Nm) Distance (Nm) - The will gain 3,258 ft (198 ft/s) and so will be 1,54 ft lower. - The will gain 3,285 ft (2 ft/s) and so will be 1,28 ft lower. In all case, it is obvious that the F-5E can evade a highspeed dogfight with such a maneuver, even against the best Mig-21, it will gain 1,ft in a quarter of a turn, even in front of the best Mig-21. Acceleration performances. Diagram show curves indicating along the time the distance from the plane to the location where all aircraft will be after 3 minutes. This way to present the data allows to quickly understanding: - How much behind another a plane (b) can be the plane (a) to rejoin it 3 minutes later: vertical distance along t= axis between curves (a) and (b). - How much time a plane (a) can be late compared to (b) and rejoin it in less than 3 minutes: search for the (b) distance at t=, go horizontal along time up the cross the (a) curve, go vertical to read corresponding time. Focusing on, the figures: Distance covered at 15, ft, start at Mach.5 / IAS 25 Kts time (s) Meaning that, neither F-5E nor can evade in simply accelerating, except if he has a significant advance (more than a quarter of a turn). The distance covered in 3 minutes by Mig-21 and F-5E at 15, ft, all planes starting at mach.5 (25Kts indicated) is described in figure 1.7. The same distance when all planes start at mach.9 (465Kts indicated) is in figure 1.8. In any configuration, the F-5E is faster than the and slower than the, the three planes being very close to each other. The is definitely the fastest. If all planes start their run at 25Kts indicated (end of a hard turn): - F5-E can rejoin the in 3 minutes being 9s late (time required to perform a 75deg turn at 25Kts) or 1Nm behind. - can rejoin the F-5E in 3 minutes being 36s late (time required to perform a 3deg turn at 25Kts) or 4.6Nm behind. That means, that if both planes are engaged in a low speed turn, neither F-5E nor Mig-21 M nor MF can evade in simply accelerating, except if he has a significant advance (more than a quarter of a turn) On the other side, in front of a, an F-5E will have no chance at all to evade. The 21bis will be able to rejoin the F-5E, even if he needs to do quite a complete turn. If all planes start their run at 465Kts indicated: 35 4 Distance covered at 15, ft, start at Mach.9/ IAS 465 Kts time (s) F5-E can rejoin the in 3 minutes being 8s late (time required to perform a 68 deg turn at 465Kts) or 1.3Nm behind. - can rejoin the F-5E in 3 minutes being 34s late (time required to perform a 39deg turn at 465Kts) or 6.1Nm behind That means, that if both planes are engaged in a high speed turn, neither F-5E nor Mig-21 M nor MF can evade in simply accelerating, except if he has a significant advance (more than a quarter of a turn). On the other side, in front of a, an F-5E will have no chance at all to evade. The 21bis will be able to rejoin the F-5E, even if he needs to do 3 quarter of a turn. can be analyzed as follow: Both planes start their run at 25Kts indicated (end of a hard turn): can rejoin the F-5E in 3 minutes being 7s late (time required to perform a 6deg turn at 25Kts) or.68nm behind. If both planes start their run at 465Kts indicated, can rejoin the F-5E in 3 minutes being 6s late (time required to perform a 5deg turn at 465Kts) or.84nm behind. Conclusion. At 15,ft, after merge, the F-5E is able to take benefit of its quickest half turn, then the and F-5E have very similar sustained turning performance when speed is lower than M.6 (35Kts IAS) and no one will have a significant advantage in such a turning fight, if speed increase again, F-5E will take the lead. The F-5E has a bigger advantage on the 21M, but still not decisive. The heavy is clearly disadvantaged at this altitude. Thursday, March 7, 213 Page - 5

6 Sustained Turn Rate (d/s) ; 2,4 max lift; 2,166 max lift; 2,29 max lift; 2,4 AoA<28; 2,63 AoA<28; 2,437 AoA<28; 2,599 ; 9.8 max lift; 1. max lift; 1. max lift; 1.8 AoA<28; 11.2 AoA<28; 11. AoA<28; 11.8 Nor neither can evade a turn fight when it has started. The demonstrate its speed superiority, and can force the F-5E to the fight if this one does not climb, or quit the turn fight if he feels in bad situation. On the other side, the F-5E has, in any case, a possibility to break the fight in performing a high speed turning climb that no Mig-21 can follow. If we try to graphically represent the main seven normalized values, we get the following diagram: Time (s) required for half turn Average turn rate in quickest half turn 1% Max Distance in 3' from M.9 75% 5% Max Sustained turn rate Max Distance in 3' from M.5 25% % 1 ft / Min sustained turn radius F-5E3 Max Turning climb rate Max level flight climb rate Average half turn radius (ft) D. Low level combat (5,ft). Turning performances. Quickest half turn At 5,ft the test compare planes on the quickest 18 deg turn. The best half turn start at mach.75 (46Kts IAS) and end in 9.8s at Mach.4 (245Kts IAS) with an average turn radius of 2,4ft. The best half turn with AoA limited to max lift start at mach.8 (49Kts IAS) and end in 1s (+.2s) at Mach.45 (275Kts IAS) with an average turn radius of 2,21 ft. It can be seen that the is equivalent to the MF when the 21bis is slower (.8s) to perform half turn and do it with a bigger average radius., M and F-5E are clearly equivalent in this area if the Mig-21 is flight to its lift limits, with an average turn rate of 18.4 d/s, and the is only.8s slower (). In the case where Mig-21 are limited to AoA28, the difference with F-5E is between 1 and 2s only. This will not allow any of these planes to take a decisive advantage on the first turn after merge. Maximum Sustained Turn Rate Focusing on, the following figure clearly shows that the sustained turn rate of the F-5 is better from 15Kts to maximum speed. This can be considered as a clear advantage in any medium-to-high speed turn fight. Graphic comparison in fig2.1 with AoA limited 28 end its half turn in 11.s (+1.2s) at Mach.61 (37 Kts IAS) with an average turn radius of 2,6 ft. Graphic comparison in fig Other Mig-21 sub-types performances are described in the following diagrams CAS (Kts) The comparative performances of the 4 aircrafts at their maximum sustained turn rate speed are described in the following table and diagram: Thursday, March 7, 213 Page - 6

7 Sustained Turn Radius (ft) Climb Rate (ft /s) 5, ft STR Turn Time for at Mach deg/s Radius , , , , And in the appendix section, fig.2.3. The advantage goes to the F-5E, the difference with the is significant but not critical (3s. for a complete 36 deg turn, around 1%), when (+5s) and 21M (+7s) are clearly disadvantaged. The F-5E sustained turn rate is superior to any Mig-21 between Mach.25 and.9 (16Kts 55Kts) and consequently have a constant advantage in offensive turn maneuver. Minimum Sustained Turn Radius At 5,ft, the figure bellow shows that the sustained turn radius are similar at low speed (under 25Kts), the Mig- 21MF can turn sharper at very low speed (135Kts), but F-5E can stay inside its opponent as soon as speed goes over 3Kts. 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, CAS (Kts) The comparative performances of the 4 aircrafts at their maximum sustained turn rate speed are described in the following table and diagram: And in the appendix section, fig.2.4 The speed range covered by this comparison allows us to say that this criterion (maximum sustained turn rate) defines the hierarchy in the low-speed turning capability (135 Kts IAS). and F-5E are equivalent, then follow and. At 5, ft an F-5E has an equivalent quickest first half turn to the best Mig-21, the best maximum sustained turn rate, and the best turn rate and an equivalent or better sustained turn radius compared to any Mig-21. 5, ft STR Turn Time for at Mach deg/s Radius , , , , In general, F-5E pilot would be in good position in accepting a dog-fight versus a Mig-21 at this altitude. He will have equal or better turn performance than any Mig-21 between mach.25 and.9 (16Kts 55Kts). Climbing performances. Non turning climb. Focusing on, the figure bellow shows that the F- 5E climbs faster all along the speed range (except under 15Kts, that is not significant), with a difference up to 5 ft/s CAS (Kts) The constant speed climb rate of each aircraft at 5, ft is described in figure 2.5. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed with Full (or Special) After Burner engaged. We can see that the has a better climb rate than the F-5E for all speed over mach.5, with an exceeding value of quite 1ft/s We can also see that the climb slower than the but the difference significantly increase when mach become higher tha.8, then F-5E get a serious advantage (466 ft/s vs 392 ft/s) If F-5E and keep a constant speed corresponding to their best climb rate, the 2,ft gain will require 3.7 seconds for the. During the same time the F-5E will gain 1,717 ft (283 ft lower). If F-5E and keep a constant speed corresponding to their best climb rate, the 2,ft gain will require 4.3 seconds for the F-5E. During the same time the will gain 1,682 ft (318 ft lower), and the will gain only 1,432 ft (568 ft lower) That means that if the F-5E pilot want to use his climb speed to break a high speed subsonic dogfight (M.9 / 55 Kts indicated) and evade in climbing, he can do it easily against a old, this can also be done against a Mig- 21MF, but not when facing a. On the other hand, the can evade in climbing against an F-5E at high speed. If we consider the same scenario where the pilot want to evade a low speed dogfight (M.5 / 25Kts indicated) by climbing at constant speed, we can see that the climb rate of the F-5E, 21bis are equivalent, then goes the and last the. Thursday, March 7, 213 Page - 7

8 Distance (Nm) Climb Rate (ft /s) Distance (Nm) So the non-turning climb rate comparison gives the advantage to the with a large margin, but the F- 5E keep a positive one in front of the at high speed (IAS < 49Kts), when the is behind in any case. Turning Climb. The figure bellow clearly shows than is such a 4G turn, the climbs much slower than the F-5E, the difference is large (more than 1 ft/s) and covers the complete speed range. Distance covered at 5, ft, start at Mach.5 / IAS 35 Kts time (s) Distance covered at 5, ft, start at Mach.9/ IAS 55 Kts time (s) CAS (Kts) 25 3 The constant speed, constant 4G climb rate of each aircraft at 5, ft is described in figure 2.6. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed and G-Load to 4. with Full (or Special) After Burner engaged. At their respective best 4G turn climb speed, the F-5E get the best climb rate. The F-5E turn rate allows a quarter turn in 12.4 sec (7.2 d/s), during this time, - The F-5E will gain 3,864 ft (311 ft/s) - The will gain 3,819 ft (37 ft/s) and so will be 44 ft lower. - The will gain 2,157 ft (173 ft/s) and so will be 1,76 ft lower. - The will gain 1,427 ft (115 ft/s) and so will be 2,437 ft lower. The F-5E can evade a high-speed dogfight with such a maneuver, against or M, it will gain more than 1,7ft in a quarter of a turn. But this cannot be used in front of the (neither the opposite) Acceleration performances. Comparison between and F-5E in figures bellow shows that there is no significant difference between the two planes at this altitude The distance covered in 3 minutes by Mig-21 and F-5E at 5, ft, all planes starting at mach.5 (35Kts indicated) is described in figure 2.7. The same distance when all planes start at mach.9 (55Kts indicated) is in figure 2.8. In any configuration, the F-5E is faster than the and equivalent to the, when the is definitely the fastest. If all planes start their run at 35Kts indicated (end of a hard turn): - F5-E can rejoin the in 3 minutes being 17s late (time required to perform a 2deg turn at 35Kts) or 1.8Nm behind. - can rejoin the F-5E in 3 minutes being 34s late (time required to perform a 36deg turn at 35Kts) or 7.8Nm behind. That means, that if F5-E and are engaged in a low speed turn, cannot evade in simply accelerating, but F-5E can. If F5-E and are engaged in a low speed turn, neither nor F-5E can evade in simply accelerating. On the other side, in front of a, an F-5E will have no chance at all to evade. The 21bis will be able to rejoin the F-5E, even if he needs to do quite a complete turn. If all planes start their run at 55Kts indicated: - F5-E can rejoin the in 3 minutes being 1s late (time required to perform a 115 deg turn at 55Kts) or 1.7Nm behind. Thursday, March 7, 213 Page - 8

9 ; 3,866 max lift; 4,545 max lift; 4,521 max lift; 4,643 AoA<28; 5,988 AoA<28; 5,948 AoA<28; 6,354 ; 25.6 max lift; 23. max lift; 22.6 max lift; 28.4 AoA<28; 24.8 AoA<28; 24.4 AoA<28; can rejoin the F-5E in 3 minutes being 28s late (time required to perform a 32deg turn at 55Kts) or 5.5Nm behind. That means, that if F5-E and are engaged in a high speed turn, cannot evade in simply accelerating, but F-5E can. If F5-E and are engaged in a high speed turn, neither nor F-5E can evade in simply accelerating. On the other side, in front of a, an F-5E will have no chance at all to evade. The 21bis will be able to rejoin the F-5E, even if he needs to do quite a complete turn. with AoA limited to max lift ends its half turn in 22.6s (-3.s) at Mach.47 (172 Kts IAS) with an average turn radius of 4,521 ft. Graphic comparison in fig3.1 with AoA limited 28 end its half turn in 24.4s (- 1.2s) at Mach.7 (267 Kts IAS) with an average turn radius of 5,948 ft. Graphic comparison in fig3.2 Other Mig-21 sub-types performances are described in the following diagrams. Conclusion. At 5,ft, the F-5E has better turning performance than any Mig-21 (except at very low speed under 13Kts) and will have a significant advantage in a turning fight. Nor neither can evade a turn fight when it has started. The demonstrate its speed superiority, and can force the F-5E to the fight if this one does not climb, or quit the turn fight if he feels in bad situation. The F-5E has, a possibility to break the fight in performing a high speed turning climb that no nor MF can follow, but not in front of a If we try to graphically represent the main seven normalized values, we get the following diagram: Time (s) required for half turn Except for the heavy, all other variants are faster than the F-5E, especially if driven at the max lift AoA by high-skilled pilots. Average turn rate in quickest half turn 1% Max Distance in 3' from M.9 75% 5% Max Sustained turn rate Max Distance in 3' from M.5 25% % 1 ft / Min sustained turn radius F-5E3 Max Turning climb rate Max level flight climb rate Average half turn radius (ft) It is clear that the F-5E get the smallest radius, mostly due to its very low speed at the end of the turn, and that the Mig-21 appears in gross weight order. E. High level combat (3,ft). Turning performances. Quickest half turn At 3,ft the test compare planes on the quickest 18 deg turn started at Mach.9 (35 Kts IAS). The advantage goes to the that need less time for its half turn, and end it at higher speed, is close behind the MF, then F-5E and last the. Maximum Sustained Turn Rate If we focus on, we can see that the F-5E advantage is only true on a very small speed range (28-32 Kts), at lower speed has a much better sustained turn rate. The ends its half turn in 25.6s at Mach.34 (127 Kts IAS, close to stall speed) with an average turn radius of 3,866ft. Thursday, March 7, 213 Page - 9

10 Climb Rate (ft /s) Sustained Turn Radius (ft) Sustained Turn Rate (d/s) 7. And in the appendix section, fig Despite its smaller maximum sustained turn rate, I would give the advantage to the for a medium-high speed turn rate at 3,ft The comparative performances of the 4 aircrafts at their maximum sustained turn rate speed are described in the following table and diagram: And in the appendix section, fig.3.3. The speed range covered by this comparison allows us to say that this criterion (maximum sustained turn rate) defines the hierarchy in the high-speed turning capability (35 Kts IAS). The advantage goes to the F-5E, but the difference with the is only 6% and then increases up to 8% for Mig- 21M and. Minimum Sustained Turn Radius At 3,ft, the can turn inside the F-5E all along the possible speed range. Cas (Kts) STR Turn Time for at Mach deg/s Radius (ft) , , , , , 25, 2, 15, 1, 5, CAS (Kts) The advantage goes to the, all over the speed range (as stated before), is close to the MF, then the F-5E, and last the heavy. The speed range covered by this comparison allows us to say that this criterion (maximum sustained turn rate) defines the hierarchy in the low-speed turning capability (185 Kts IAS). A driven by a high-skilled pilot has the best performances over all turning criteria at 3,ft bellow M.75 / 29Kts IAS: quickest half turn, best sustained turn rate or radius. The F-5E pilot can only take advantage of a better turn rate between 29 and 33Kts. If the pilot can chose its combat speed according the desired tactic he will keep an advantage in both offensive and defensive turn maneuver. For and older, the advantage is not so clear, but it keep a quicker half turn and a better turn radius at low speed, so the pilot would prefer a low speed dogfight. The heavier had a slower half turn, high speed turn rate and a higher low speed turn radius, so the pilot would prefer avoiding dog-fighting versus F-5E at 3,ft. All Mig-21 can take advantage of the quickest first half turn, and then get in a low speed, low radius fight, can even chose to go in a medium speed (25Kts) turn rate fight at its advantage. In general, F-5E pilot would not be in good position in accepting a dog-fight versus a Mig-21 at this altitude, he would have superior performance only against old (Mig- 21M) or heavy (), or in a very small speed range (29-33Kts) against a. Climbing performances. Non turning climb. The figures bellow shows that the generally climbs faster than the F-5E. This is obvious in supersonic domain (that is not really relevant in close air combat as it is in an interceptor role), and the difference is much less significant at low speed. The only speed domain where the F-5E climbs better is the high-subsonic (M.85/M.92), and even there, the advantage is not so large. 3 The comparative performances of the 4 aircrafts at their maximum minimum sustained turn radius speed are described in the following table and diagram: , ft STR Turn Time for at Mach deg/s Radius (ft) , , , , CAS (Kts) The constant speed climb rate of each aircraft at 3, ft is described in figure 3.5. The value (in ft /s) is the climb Thursday, March 7, 213 Page - 1

11 Climb Rate (ft /s) rate when fly path is adjusted to keep constant True Air Speed with Full After Burner engaged with Full (or Special) After Burner engaged. We can see that the Mig-21 have a better maximum climb rate (243 ft/s for the 21M, 274 ft/s for 21MF, 34 ft/s for the 21bis) that the F-5E (235 ft/s), but these values are not reached at the same speed: when F-5E get its best climb rate in subsonic (M.9 / 35 Kts IAS), Mig-21 get their own in low supersonic (M1.1 / 425 Kts IAS). If we restrict the analysis to subsonic flight F-5E get the best climb rate at Mach.9: 235 ft/s compared to 197, 212 and 219 for respectively 21M, MF and bis. If all aircraft keep a constant speed of mach.9 / 35 Kts indicated, the 2,ft gain will require 8.4 seconds for the F-5E during the same time - gains 1,676 ft (348 ft lower) - gains 1,778ft (222 ft lower) - gains 1,843 ft (157 ft lower). That means that if the F-5E pilot want to use his climb speed to break a high speed subsonic dogfight (M.9 / 35Kts indicated) fight and evade in climbing in, he can do it against a, it will be more difficult against a Mig- 21MF and quite inefficient against a. If we consider the same scenario where the pilot want to evade a low speed dogfight (M.5 / 185 Kts indicated) by climbing at constant speed, the situation is quite inverted: - The requires 16.6 s to gain 2,ft, during this time the F-5E will gain only 1,54 ft (46 ft lower) - The requires 16.7 s to gain 2,ft, during this time the F-5E will gain only 1,547 ft (453 ft lower) - The requires 18.3 s to gain 2,ft, during this time the F-5E will gain only 1,693 ft (37 ft lower) Meaning that all Mig-21 can evade a low speed dogfight (IAS < 2 Kts) in climbing, but the F-5E cannot. The last case is the one where all planes are in low supersonic fight (at M1.1 / 425 Kts indicated) and try to evade in climbing: - The require 6.6 s to gain 2,ft, during this time the F-5E will gain only 625 ft (1,375 ft lower) - The require 7.3 s to gain 2,ft, during this time the F-5E will gain only 693 ft (1,37 ft lower) - The requires 8.2 s to gain 2,ft, during this time the F-5E will gain only 781 ft (1,219 ft lower) Meaning that all Mig-21 can evade a low supersonic speed in climbing, but the F-5E cannot. So the non-turning climb rate comparison gives the advantage to the Mig-21 at low (IAS < 2 Kts) and supersonic speed (M1.1 / 425 Kts indicated), when the high subsonic (M.9 / 35 Kts indicated) case see the F-5E better than all Mig-21. Turning Climb. The figure bellow shows that the climbs generally faster than the F-5E in a 2G turn, except in the speed domain of close air combat at this altitude, from 27Kts to 37Kts, the F-5E climbs faster. The advantage of the in supersonic domain is very helpful in the last minutes of a high-speed/high altitude rear aspect interception, but not after the fight is really engaged, speed falling to subsonic quite immediately The constant speed, constant 2G climb rate of each aircraft at 3, ft is described in figure 3.6. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed and G-Load to 2. with Full After Burner engagedwith Full (or Special) After Burner engaged. In a high subsonic (M.9 / 35 Kts indicated) 2G turn, the F- 5E get the best climb rate. The turn rate is the same for all and allows a quarter turn in 25.2 sec (3.57 d/s), during this time, - The F-5E will gain 3,688 ft (146 ft/s) - The will gain 2,479 ft (98 ft/s) and so will be 1,29 ft lower. - The will gain 2,72 ft (18 ft/s) and so will be 97 ft lower. - The will gain 2,866 ft (114 ft/s) and so will be 968 ft lower. In all case, it is obvious that the F-5E can evade a highspeed dogfight with such a maneuver, even against the best Mig-21, it will gain 9ft in a quarter of a turn. On the opposite, it is clear that as soon as both aircrafts enter a supersonic turn (Mach 1.1 / 425 Kts indicated), all Mig-21 can evade in a 2G turn climbing, as the F-5E is not even able to climb (less than 2 ft/s) when Mig-21 can reach 165 ft/s (21M), 195 ft/s (21MF) and 214 ft/s (21bis). But this cannot be used by the Mig-21 to evade a subsonic fight as it requires more than 2s to go from M.9 to M1.1 (35 to 425 Kts indicated). CAS (Kts) Acceleration performances. Focusing on vs. F-5E give the following figures: Thursday, March 7, 213 Page - 11

12 Distance (Nm) Distance (Nm) Distance covered at 3, ft, start at Mach.5 / IAS 185 Kts time (s) Meaning the Mi-21bis can make a half turn at constant speed (requiring less than 45s), then accelerate and find a firing solution less than 3 minutes after the first cross. If all planes start their run at 35Kts indicated (M.9), Mig- 21bis can be 7Nm behind the F-5E and rejoin it in less than 3 minutes Distance covered at 3, ft, start at Mach.9/ IAS 35 Kts time (s) Comment: if the Mig-21 choose the quickest half turn instead of constant speed one, the end of turn speed will not allow it to rejoin the F-5E in 3 minutes, so the good strategy for the Mig-21 at merge if the pilot see the F-5E trying to avoid the combat is clearly a constant high speed half turn If both planes start their run at 185Kts indicated (M.5, end of a hard turn), can be 4.3Nm behind or 4s late. That means, that if both planes are close together at this speed, but facing each other, the F-5E deciding to accelerate straight forward, the can make a half turn at constant speed (requiring less than 4s) then accelerate and find a firing solution less than 3 minutes after the first cross. If all planes start their run at 35Kts indicated (M.9), Mig- can be 6Nm behind or 38s late If both planes are close together at this high subsonic speed, but facing each other, the F-5E deciding to accelerate straight forward, the Mi-21MF can make a half turn at constant speed (requiring no more than 35s as explained in high speed turn performance section), then accelerate and find a firing solution less than 3 minutes after the first cross. The distance covered in 3 minutes by Mig-21 and F-5E at 3, ft, all planes starting at mach.5 (185 Kts indicated) is described in figure 3.7. The same distance when all planes start at mach.9 (35 Kts indicated) is in figure 3.8. In any configuration, the F-5E is slower than any Mig-21, and and are very close. Comparison with gives: Conclusion. At 3,ft, the has, compared to the, a quicker half turn, a better maximum sustained turn rate except between M.75 and M.9, a smaller minimum turn radius, it can rejoin it being 6 Nm behind or 4 second late, it has also a better equivalent maximum climb rate, even if it is true only when supersonicxcept between mach.85 and.95. The only advantage of the F-5E in such a configuration is its high subsonic turning climb rate that can be used to go out the dogfight or better high speed turn rate if the Mig-21 stays in this speed range (M ). So, it is easy to say that the has a global advantage over the F-5E at this altitude especially is speed goes below M.75, or become supersonic. For the, the situation is similar at low speed (under 25Kts indicated), but the F-5E may take advantage of its better high subsonic turn capabilities in offensive maneuver, and of its subsonic climb rate to quit. The is clearly not at its advantage at this altitude in offensive sector, but it can disengage by accelerating, and F-5E will never be able to re-engage. If we try to graphically represent the main seven values: - Average turn rate during quickest half turn - Maximum Sustained Turn rate - 1ft / Minimum Sustained Turn Radius - Maximum Subsonic llevel flight Climb Rate (Mach <.9) - Maximum Subsonic Turning Climb Rate (Mach <.9) - Distance Covered in 3 from Mach.5 - Distance Covered in 3 from Mach.9 In normalizing them (in percentage of the best value), we get the following diagram: If both planes start their run at 185Kts indicated (M.5, end of a hard turn), can be 6Nm behind the F-5E and rejoin it in less than 3 minutes. Thursday, March 7, 213 Page - 12

13 Max Distance in 3' from M.9 Max Distance in 3' from M.5 Max Turning climb rate Average turn rate in quickest half turn 1% 75% 5% 25% % Max Sustained turn rate Max subsonic Climb rate 1 ft / Min sustained turn radius F-5E3 Gode configuration. At break release before take off the F-5E have 6,77lbs of fuel Military thrust climb to optimum cruise altitude of 3,ft is made to conserve fuel more time on MIG CAP Station. At top of climb, remaining fuel is 4,782 lbs. All the way to MIG CAP station fighters receive information from ground radar at Marda pass. After external fuel is used, tank is not released (as fuel tanks are very soon used up in the war). It will be jettisoned only if combat occurs. After reaching Gode MIG CAP station, F-5E are resuming racetrack orbit pattern at 3,ft. At start of MIG CAP orbit remaining fuel is 3,879lbs. F. Ogaden War: Combat over Gode Aircraft configuration. take off from Dire Dawa airbase in Ethiopia for Gode Mig CAP station which is positioned 5 km (3 Nm) from Gode in direction of Baidoa Mig base in Somalia. Mission is to protect F-5A strike in vicinity of Gode. Weapons load is two AIM-9B-2 and full gun ammo. Fuel load is full internal fuel and one 275Gal external fuel tank on CL station. take-off from Baidoa, weapons load is two R-3S missiles and full gun ammo. Fuel load is full internal fuel and one 765l external fuel tank on CL station. Gode configuration. At break release before take off the have 2,48kg of fuel Take off and climb to optimum cruise altitude of 9,m leave it with 1,956 kg of fuel CGI radar at Baidoa airbase vector the MIGs to F-5E, after external fuel is used, Mig-21 jettison their 765l tank from center line stations. At 1 Nm (18 Km), visual contact is established, MIGs are accelerating to combat speed 1Nm from Gode MIG CAP Station to engage F-5E. configuration at start of combat (1,78 kg or 2,58l of fuel) defines a gross weight of 17,337 lbs (7,854 kg) and a Drag Index of 12. Clean Aircraft (no fuel) : 5,76 kg 2 gun ammo (Gsh 23) : 75 kg 2 Under-wing pylon : 45 kg 1 Center line pylon : 24 kg 2 Missile rails for R-3S : 41 kg 2 Missile R-3S : 15 kg internal fuel : 1,78 kg This gross weight leads to the following load factor limitation: For lower than.8 : 7. G For greater than.8 : 6. G In this scenario, Marda radar informs F-5E of several contacts taking off from Baidoa MIG base in Somalia and they meet the Mig with a remaining fuel load of 3,77 lbs. combat configuration at start of combat is Drag Index of 38. Clean Aircraft (no fuel, pilot) : 1,659 lbs DI 2 Gun ammo : 394 lbs DI + 2 Missiles AIM-9 : 34 lbs DI Missile rails for AIM-9 : 98 lbs DI + 2 Under wing Hook : lbs DI +4 1 Center Line pylon : 17 lbs DI +14 Zero fuel weight : 11,661 lbs Internal fuel (JP-4) : 3,77 lbs (68%) Gross weight : 14,738 lbs Entering the fight at 2,ft In this section we will analyze the situation where the two opponents meet at medium altitude (2,ft) with the gross weight defined previously. It seems to be compliant with the reported combat where merge occurred around 18,ft. Compared to the Combat configuration sections, we will see that the is disadvantaged, because he has, in proportion, more fuel than the F-5E (88% of its internal capacity compared to 68%). Turning performances. Quickest half turn At 2,ft the test compare planes on the quickest 18 deg turn. The start its half turn at Mach.9 and end if in 16s at Mach.36 (167Kts IAS) with an average turn radius of 2,728ft. with AoA limited to max lift start its half turn at Mach.95 end its half turn in 16.s (same time) at Mach.52 (241 Kts IAS) with an average turn radius of 3,763 ft. Graphic comparison in fig4.1 Thursday, March 7, 213 Page - 13

14 with AoA limited 28 end its half turn in 17.4s (+1.4s) at Mach.7 (327 Kts IAS) with an average turn radius of 4,532 ft. Graphic comparison in fig4.2 and F-5E need the same time to do the quickest half turn (if the is flew to its max lift), and more do it with a much smaller radius, this will give the F-5E a very small advantage at the merge at this altitude. Maximum Sustained Turn Rate The sustained turn rate of the 2 aircrafts are described the appendix section, fig.4.3. The F-5E sustained turn rate is superior to the one between Mach.34 and.9 (16Kts 425Kts). The difference between maximum values (7.7 d/s for F-5E and 6.9 for ) is not critical but give a constant advantage in offensive turn maneuver to the F-5E in quite all the subsonic area. Minimum Sustained Turn Radius. The sustained turn radius of the 2 aircrafts are described the appendix section, fig.4.4. The graphic shows clearly that the minimum radius goes to the F-5E, (but the difference remains very small: 8 ft) and there is no real advantage at low speed for the. Both aircraft have similar performance in defensive turn maneuver. In general, at 2, ft is this particular configuration, the F-5E will have a marginal advantage at the merge, will keep it in sustained turn combat all along the speed range, and does not even has its usual very low speed advantage. If the tactical configuration of the engagement is not clearly in favor of the, I will not be surprise the F-5E taking the advantage upon his opponent in a turn fight. Climbing performances. Non turning climb. The constant speed climb rate of each aircraft at 2, ft is described in figure 4.5. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed with Full (or Special) After Burner engaged. We can see that the and have very similar climb rate up to Mach.9, with a small advantage to the F- 5E, then, going supersonic the advantage changes to Mig21MF. At mach.9 (425Kts IAS) the difference is really small (34ft/s versus 287) : when F-5E gains 2,ft (in 6.6 s), the gains 1,884 ft, and a difference of 116ft is not enough to say the higher plane has evade the turn fight this way. If we consider the same scenario where the pilot want to evade a low speed dogfight (M.5 / 23Kts indicated) by climbing at constant speed, we can see that the situation is the same, when F-5E gains 2,ft (in 12.9 s), the Mig- 21MF gains 1,892 ft, and a difference of 18ft is not enough to say the higher plane has evade the turn fight this way. So the non-turning climb rate comparison gives no clear advantage, nor the F-5E, nor can the evade a turn fight in just climbing, nor at low speed, neither at high subsonic speed. Turning Climb. The constant speed, constant 3G climb rate of both aircraft at 2, ft is described in figure 4.6. The value (in ft /s) is the climb rate when fly path is adjusted to keep constant True Air Speed and G-Load to 3. with Full (or Special) After Burner engaged. In a high subsonic (M.9 / 425Kts IAS) 3G turn, the F-5E get the best climb rate. The turn rate is the same for all and allows a quarter turn in 16.1 sec (5.6 d/s), during this time, the F-5E will gain 2,81 ft (129 ft/s), and the will gain 1,473 ft (91 ft/s) and so will be 68 ft lower. The F-5E can evade a high-speed dogfight with such a maneuver, it will gain 2ft in a quarter of a turn. Acceleration performances. The distance covered in 3 minutes by and F-5E at 2, ft, starting at mach.5 (23Kts indicated) is described in figure 4.7. The same distance when all planes start at mach.9 (425Kts indicated) is in figure 4.8. In any configuration, the is faster than the F-5E. If both planes start their run at 425Kts indicated (at the merge or in the middle end of a high G turn) can rejoin the F-5E in 3 minutes being 21s late (time required to perform quite a 18deg turn at 425Kts) or 4.Nm behind. If both planes start their run at 23Kts indicated (end of a hard turn) can rejoin the F-5E in 3 minutes being 24s late (time required to perform a 15deg turn at 25Kts) or 2.55Nm behind. That means, that if both planes are merging or engaged in a turn, whatever the speed is, the F-5E cannot evade in simply accelerating, except if he has more than a half turn advance, on the other hand, can evade quite easily this way. Conclusion. At 2,ft, the can force the F-5E to the fight (if the F-5E localize its opponent at 4Nm or less), but as soon he will enter a turn fight, the F-5E will have the advantage. The F-5E keeps the ability to break a turn fight in turn climbing, where the cannot follow, if he goes to a bad situation. On the opposite, the can also quit the dogfight in level-flight acceleration. Thursday, March 7, 213 Page - 14