This article introduces the F-4E-45MC, the MiG-21 bis and the Mirage F1. This table shows their characteristics and parameters along several other aircraft.
Reference Data
As mentioned in the previous video discussing the F-14A and the F-14B, engine thrust is only one of the many variables needed to describe an aeroplane’s performance. For example, the three engines here discussed — the French SNECMA Atar 9K-50, the American General Electric J79, and the Soviet Tumansky R25 — all provide, more or less, the same amount of thrust. This is where aerodynamic solutions, aircraft design, construction materials, weight, and many more details come into play. For example, the Mirage F1 is more than 20% heavier than the MiG-21. The F-4 is even heavier, but it is the only fighter of the three sporting two engines and two crew members.
When controllable parameters are added, such as the internal fuel and various types of payload affecting the total weight and the Drag Index, determining the best-performing aircraft is nearly impossible without circumscribing the scenario in a defined set of rules.
This chapter of the study follows the same modus operandi as the previous one, with different sets of scenarios and tests through which each fighter has been tested multiple times.
F-4E Phantom II
A Navy design adopted after a long gestation, the F-4 Phantom is one of the most ubiquitous fighter jets in the world and, hands down, the best module in DCS quality-wise. Currently, only the F-4E-45MC is available in the game, a version that includes features introduced until 1974. This makes this version of the Phantom II a contemporary of the earliest F-14 Tomcat, which is unfortunately not present in the game.
The F-4 II entered US AF service long before the mentioned date. This table shows some of the differences between the F-4C up until the F-4G (from Guns and Slats: F-4E Peculiarities – Phantom Phamiliarisation II).
(Guns and Slats: F-4E Peculiarities – Phantom Phamiliarisation II)
Most British Phantom IIs mounted an alternative to the turbojet J79: two Rolls-Royce Spey low-bypass turbofan engines. Capable of providing more thrust and reducing consumption, not to mention the smoke, the Spey provided other positive characteristics at the cost of a lower maximum speed.
Unfortunately, I doubt we will ever see a proper British Phantom in DCS, and, probably, F-4J or F-4S will end up serving in the virtual British forces.
Back to the numbers,I have extensively covered the F-4E’s features on FlyAndWire, so let’s jump straight into numbers and charts, starting with the ground-level performance.
Ground-level Performance
Down in the weeds, the performance of the clean F-4E is excellent both in reheat and military thrust settings. The J79’s afterburners pushed the Phantom through the transonic range with ease, and only the addition of a heavy external payload prevented it from doing so. Without the “bags”, in fact, the tested Phantom carries the normalised 10,000 lbs of fuel, plus a non-indifferent set of four AIM-9 Sidewinder and four AIM-7 Sparrow, the latter mounted in wells capable of reducing drag. The configuration sporting fuel tanks is instead very heavy: three massive tanks capable of providing an additional 8700 pounds of fuel. The idea was to mimic a high-drag configuration, something similar to the many air-to-ground heavy loadouts this magnificent aircraft can carry while maintaining a useful air-to-air setup. Worst case, the bags can be jettisoned. The acceleration decreases noticeably at military thrust, especially when the fuel tanks are loaded. The 40-second detail shows how the “clean” and “payload” configurations behave somewhat closely, but the bags are really having an impact, not only in terms of top speed, but also acceleration.
High-altitude Performance
The 30,000 ft scenario shows the stunning power of a clean F-4E Phantom II. This aircraft is fast, and the envelope almost resembles a line rather than a curve. As a brief parenthesis, I wonder how the “hard wing” pre-slats Phantom would behave in terms of raw performance, as the slats added to the F-4E traded manoeuvrability for speed by increasing drag.
Back to the charts, the addition of payload and/or fuel tanks does not impact the curves until the second half of the transonic region. In this area of the envelope, in fact, the 4-by-4 AIM-7 and AIM-9 configurations suffer less. Remarkably enough, this setup and payload plus fuel tanks do not seem to stop their acceleration at Mach 1.2.
The Military thrust tests are quite peculiar as each curve differs. “Clean” seems to increase its acceleration as the fighter enters the transonic region. Then, the trend softens close to M1, but the Phantom still accelerates and reaches M1.08 at the end of the test. The Phantom can therefore supercruise, although, being clean, its usefulness is dubious. In fact, moving forward, the 4-by-4 configuration is capable of settling at a speed very close to M1. I have not checked the DI values, acronym for Drag Index, but I guess the AIM-9s may be the greatest drag source in this setup. If there is enough interest, I can test a 4-Sparrow and full internal fuel configuration and verify whether it is capable of supercruising, perhaps at a higher altitude, or after a minor unload to ease the transonic transition. Nevertheless, it is a great indicator of the qualities of the Phantom as a fighter jet design.
When three fuel tanks are added, the outcome is quite interesting. In particular, the acceleration is drastically impacted, but, contrary to other aircraft, the trend persists. In other words, the speed is increased at a very slow pace, to the extent that the cutoff of M.7 has eliminated more than half of the collected values, but the Phantom keeps accelerating.
The 40-second details show three different groups of results: the clean reheat test skyrocketed away, leaving the payload and payload plus fuel tank configurations close together. At Mil power, instead, clean and payload behaved similarly, but the payload plus bags setup lagged behind.
Fuel Considerations
The pair of General Electric J79 powering the F-4E are turbojets, belonging to an older generation of aircraft engines. In fact, they were later superseded by the first generation of afterburning turbofans. An example is the Pratt&Whitney TF-30 used by the F-14A and described in the previous video of this series. Shortly after, newer designs like the F100 mounted the F-15 were introduced. As mentioned, the British Phantoms II were usually powered by the Rolls-Royce Spey.
Back to the study, the J79 are inefficient at low altitudes and with reheat. However, they perform much, much better at 30,000ft, de facto doubling the endurance, from 7 to 15 minutes if supplied only by the internal fuel, or up to 26 minutes with a heavy 3-bags loadout. The military thrust scenarios somewhat reflect this observation. At medium-to-high altitudes, in fact, the endurance is more than doubled compared to low altitudes. With three external tanks, the Phantom II has fuel for days. It would be interesting to calculate the best configuration, but just eyeballing the collected data, two bags plus maintaining a decent altitude should result in a pretty good trade-off between flight time capability, drag, and speed.
Mikoyan-Gurevich MiG-21bis
Codenamed “Fishbed” by NATO, the MiG-21 is a good challenger to the Phantom II for the title of the most iconic mid-Cold War aeroplane. Both were produced in staggering numbers, almost 14,000 for the MiG, over 5,100 for the Phantom II.
The Fishbed is the first single-engine fighter aeroplane analysed so far. Throughout its long history, this lightweight fighter was tasked with a plethora of roles, from point-defence interceptor, to air-to-ground and reconnaissance. DCS’ MiG-21bis has been one of the very first modules added to the original Kamov Ka-50 and A-10C. This version represents a 1970s evolution of the Fishbed, with increased internal fuel, improved radar, powerplant and engine and capabilities, such as the internal gun, compared to the original variants.
The top-down view of the MiG-21 reveals some core features of its design: the thin body and the delta wings enabled the Fishbed to reach extremely high speeds. The initial Tumansky R11 was quite underpowered, delivering 38.7 kN at military and 60.6 kN with reheat. The “bis” received the upgraded Tumansky R25-300. This compact afterburning turbojet was relatively low-powered, and capable of generating 41 kN thrust dry, and 70 kN with afterburner. For example, each single General Electric J79 generated circa 53 kN dry and 80 kN with reheat. Keep in mind the low-power output of the military thrust setting because it will tell us a lot about the performance of this aircraft.
Ground-level Performance
Let’s start the data analysis, as usual, from the ground-level test. As we have just discussed, the power output of the Tumansky R25-300 with reheat is 70% higher, and we can really see that. In fact, past M1.1, the engine overspeeds, and a flameout occurs. Since there is minimal warning in the cockpit, the pilot has to monitor the airspeed indicator. Moreover, the acceleration between M1 and M1.1 is eyewatering, thus requiring very careful management.
The external payload test is one of the most complete possible, with four R-60s and a pair of R-13M1s. The performance of the Fishbed is impacted, but only slightly. The Tumansky R25-300 pushes the aircraft through the transonic region with ease. At the end of the test, the top speed is slightly lower than the overspeed threshold.
The fuel tank test adds an 800L tank underneath the belly, increasing the fuel capacity by approximately 1400 lbs. The additional payload causes the Fishbed to reduce its top speed tangibly, and the aircraft fails to break through the high-drag transonic range.
If the afterburner is not used, the output of the Tumansky R25-300 turbojet is limited, and the MiG-21 shows it. Interestingly, there is not a lot of difference between the loadout settings. Whether the Fishbed is clean or with stores and bags, the acceleration is mediocre. That being said, the trend seems to continue, and the curve does not flatten. Ergo, a pilot can use reheat to supplement the lacklustre acceleration, then revert to military thrust to maintain the high speed so obtained.
High-altitude Performance
At 30,000ft, the charts become even more interesting. The reheat curves show how fast the MiG-21bis can go. It passes the transonic region with ease and aggressively accelerates towards Mach 2. The presence of six air-to-air missiles affects the performance only marginally. The most significant impact on the Fishbed’s performance is the combination of missiles and the 800-litre fuel tanks. However, even in such a case, the MiG continues to accelerate homogeneously but at a lower grade.
The military thrust tests baffled me, so I gathered more runs than usual. The average is shown in the chart. As you can see, the trend is similar across the three configurations and highlighted by poor acceleration characteristics. “Clean” maintains a positive trend, followed by the air-to-air configuration. The addition of the external fuel tank flatlined the curve instead. I had to spawn the MiG-21 at M.67 rather than the usual M.6 or lower to collect enough meaningful data.
Fuel Consumption
Regarding fuel consumption and autonomy, the Tumansky R25-300’s ground-level flameout leaves use without one crucial parameter. If there is enough interest, I can collect more data while maintaining a speed close to M1.1 and verify the fuel consumption over time. If the Military thrust setting is an indicator, we may find an extremely high fuel consumption of circa 720 lbs per minute.
Although the performance in military thrust setting up high was poor, the endurance benefits tangibly. Although we are far from the Phantom II’s endurance with three bags, the MiG-21 can stay in the air for a decent amount of time, which can be improved even more by adjusting altitude and thrust settings.
Mirage F1CE
The French aviation industry is one of the most underrepresented in video games, a fate similar to many unforgivably forgotten British products such as the Hawker Hunter or the English Electric Canberra. With most players focused on the Cold War and the conflict between US-NATO and the Soviets or modern Russia, it is easy to lose sight of the aeroplanes that literally shaped the world as we know it today. Aeroplanes from the Mirage family to the Super Étendard and the SEPECAT Jaguar participated in many conflicts.
The Mirages and locally built variants were staples of the IDF AF and later fought around the world, from Pakistan to the Falklands-Malvinas. In this theatre, the Exocet-carrying Super-Étendard was one of the greatest threats to the British Forces. The Iraqi Air Force also fielded five Super-Étendard, along with the Mirage F1. They faced Iranian F-14A Tomcats and various versions of F-4 Phantom II, F-5 A/B Freedom Fighter and E/F Tiger II.
The Mirage F1 also served alongside European forces, such as the “Ejército del Aire”: the Spanish Air Force. In DCS, we find multiple versions of the Mirage F1, including a two-seater and a modernised version. This study covers the first to enter service: the Mirage F1 CE. This aircraft, originally introduced in French service in 1974, was purchased by the Spanish in the mid-to-late 1970s. In addition to French-built ordnance, it features familiar missiles such as the AIM-9 Sidewinder.
The Mirage F1 CE is powered by a single turbojet SNECMA Atar 9K-50. The roots of this family of engines date back to the Second World War. Similarly to other Allies countries, such as the USA or the Soviets, the French learnt a lot from the technological innovations developed by Nazi Germany, or directly employed German engineers. In particular, the SNECMA Atar engines are derived from the BMW 018 project.
The Atar 9 is a late ’50s design; the result of a decade of improvements. It went on to power aircraft such as the Mirage III and V and the Super-Étendard. The 9K-50 is a further improvement with better fuel consumption and powers the Mirage F1.
The payload carried by the Mirage F1 in these tests filled every available station: the air-to-air setup features two AIM-9 Sidewinders and two Super 530EM. The fuel tank loadout includes one underbelly 1137-litre bag.
Ground-level Performance
At ground-level altitude, the Mirage F1 shows two faces depending on whether the reheat is used. The afterburner provides the F1 with a considerable acceleration, almost non-affected by the additional external loadout. However, the French fighter seems to be hitting a wall as it enters the transonic range. As more payload is added, the more the F1 struggles to reach supersonic speed. The speed settles at circa M.95 when the fuel tank is added.
The Atar 9K produces circa 45% more thrust with reheat. The effect of not using the afterburner is dramatic, and the acceleration is sluggish. Interestingly the trend is somewhat similar throughout the three configurations, the additional external load simply decreases the pitch of the curve, and the speed at which the Mirage settles. This appears to be another case where the acceleration provided by the afterburner is a solid means of pushing the aircraft to a speed then maintained by the military thrust setting.
High-altitude Performance
The curves at 30,000 ft are some of the most peculiar discussed so far. When reheat is used, the three configurations almost mirror each other, the “payload” set up as a sort of bisector. The clean Mirage F1 is extremely fast, de facto unaffected by the transonic region. At the end of the data-collection period, it shows no signs of slowing down at all.
The heaviest loadout tested, comprising air-to-air missiles and a fuel tank, really struggles. The acceleration is not bad per sé, but the transonic region is a wall too tough to crack. Although beyond the purpose of this study, a pilot may still be able to unload, accelerate and maintain supersonic speed even with such a loadout.
If the fuel tank is not carried instead, the Mirage F1 is fully armed and extremely fast, and the transonic region only partially affects its performance.
Without reheat, the Mirage F1 shows a behaviour almost identical to the one observed down in the weeds. The clean configuration is extremely fast, and the aircraft appears to be barely able to supercruise. Although, this is quite an arguable achievement since the F1 seems to settle at circa Mach 1.02. Still, at Mach 1 the peak of the transonic drag is almost passed, and unloading may help the aircraft to achieve and maintain higher speeds.
Interestingly, adding air-to-air weapons only marginally affects the overall performance, as the Mirage settles close to Mach 1, but the acceleration seems to be the most affected. The quite sized 1137-litre fuel tank instead provides too much drag and the Atar 9K-50 struggles at military thrust configuration.
This chart shows how a pilot can save fuel by maintaining a conservative thrust setting, then jettisoning the fuel tank and sprinting through the transonic region with ease, even with a full air-to-air loadout.
Fuel Considerations
Fuel-wise, the Atar 9K dash 50 shows the most unusual results. This engine seems efficient at high altitudes, whereas it is poor at best down low when reheat is used. The fuel consumption at low altitudes is, in fact, 360% compared to 30,000 ft. In the military thrust setting, the endurance increases considerably. Nevertheless, the Atar still uses more than twice the quantity of fuel at low altitudes compared to up high.
The next part of the study will compare the characteristics of the F-4E, the MiG-21bis and the Mirage F1 directly.
FlyAndWire 