El MIG-21 es buena opción para Nicaragua por su bajo costo y seguramente serían las ultimas versiones rusas del aparato.
The Phantom could outclimb the MiG-21 though couldn’t out-turn it. The F-4 had a superior roll rate but it was not a good turner. It was built for brute speed and climbing ability. Still it was a good dogfighter if flown at high speeds and the pilot knew how to exploit MiGs’ weaknesses. Down, at 10,000 ft, with its tremendous thrust-to-weight advantage, the Phantom was in particular superior to MiGs. It could maintain altitude even in an 8-G turn where MiGs lost control and here the F-4 was considerably faster, able to escape from an awkward situation (750 knots as against MiG’s 570 knots).
Down, at 10,000 ft, with its tremendous thrust-to-weight advantage, the Phantom was in particular superior to MiGs. It could maintain altitude even in an 8-G turn where MiGs lost control and here the F-4 was considerably faster, able to escape from an awkward situation (750 knots as against MiG’s 570 knots).
The delta--wing design of the Mig-21 also lost energy in turns faster than the F-4 did. The technique therefore was to force the Mig-21 to make vertical turns until its air speed fell below a critical value. With the Mig slowed down, the F-4 was in the superior posi-tion. In a turning battle, the F-4 had to keep its speed up, to insure that the turn rate was even. The Mig-21 was also optimized for high altitudes – above 30,000 feet. At lower altitudes the F-4’s higher-thrust engines gave it an advantage.
In 1967, the Defense Intelligence Agency secretly acquired a single MiG-21. Comparisons between the F-4 and the MiG-21 indicated that, on the surface, they were evenly matched. At a speed of Mach 0.9 at 15,000 feet the instantaneous turn rates of the two planes were nearly identical, at 13.5 deg/sec. At Mach 0.5, the MiG-21 held the edge at 11.1 deg/sec versus 7.8 deg/sec for the F-4. But air combat was not just about a turn rate. In the final analysis, it was the skill of the man in the cockpit. A joint air force–navy team was assembled for a series of dogfight tests. The project was code-named ‘Have Doughnut’ and these tests showed this most strongly. When the air force pilots flew the Mig-21, the results were a draw – each fighter would win and lose some fights. There were no clear advantages. The problem was not with the planes, but with the pilots flying them.
One of the navy pilots was Marland Townsend, then commander of the
F-4 training squadron at NAS Miramar. He was an engineer and a Korean War veteran and had flown almost every navy aircraft. When he flew against the Mig-21, he would outmaneuver it every time. The air force pilots would not go vertical in the Mig-21. Townsend would pull up into a vertical climb, do a roll, as he came over the top, spot the Mig-21, and then line up on its tail.
Another navy pilot, Tom Cassidi, was watching as Townsend ‘waxed’ the Mig-21 pilots. Cassidi climbed into the Mig-21 and went up against Townsend’s F-4. This time the result was far different. Cassidi was willing to fight in the vertical to the point where it was buffeting, just above the stall. Cassidi was able to get on the F-4 tail. After the fight, they realized the Mig-21 turned better than the F-4 at lower speeds. The key was for the F-4 to keep its speed up.
Next day they met again. When Townsend spotted the Mig, he lowered the F-4’s nose and pulled into a high-g turn, maintaining a speed of 450 knots. The Mig-21 could not follow and lost speed. Townsend then pulled the Phantom into the vertical. The Mig lacked the energy to follow, and Cassidi dove away. Townsend rolled over the top and pulled behind the Mig-21. Nothing Cassidi did could shake the F-4. Finally, the fight was called off when the Mig ran low on fuel. What had happened was remarkable. The Phantom defeated the Mig; the weakness of the Soviet fighter had been found. But it was also clear that the Mig-21 was a formidable enemy.
In the lower speed range, the Phantom’s wing loading was high, and although it could turn with a MiG-21 at high transonic speeds, it lost out badly in a turning fight when the speed bled off. However, the F-4 handles well in the low-speed range too. It will stay slow and be very controllable at slow air-speeds, if you know how to handle it.
Its delta wing allows the MiG-21 to turn very well, but the induced drag of that configuration ‘bleeds’ energy rapidly and when MiG-21 turns, it costs. So the trick is to get the MiG-21 down to an altitude below 20,000 feet. That’s where the Phantom really performs well with its wing; it turns and accelerates well. But if you get above 20,000 feet and tangle with a MiG-21, it will chew you to pieces because of the advantages of its wing.
The MiG-21 nearly matched the Phantom’s top speed but the Phantom had greater power and could use ‘high energy maneuvers’, against which the MiGs had higher maneuverability, especially in instantaneous rate of turn which, if applied at the right moment, could be used to escape the Phantom. High maneuverability was at such a premium against the Phantom that many of the best North Vietnamese pilots preferred the more maneuverable MiG-17 to the MiG-21. Both MiGs were small and not easy to pick out at a distance, while the Phantom was not only big but had notoriously smoky engines, making it even easier to see first.
The Phantom was a superb aircraft but not a natural, maneuverable dogfighter. The high-energy maneuvers it could perform with its large power reserves gave its pilots the ability to turn the tables in a dogfight. The age of aerial combat with missiles had arrived. The problem was that the F-4 was arriving in battle with air-to-air missiles designed for attacking bombers high in the stratosphere, not fighters at close quarters, and its reliance on missiles meant that many opportunities which presented themselves could not be used because of the delay and restrictions which getting a radar lock-on imposed. It was decided to give Phantom pilots a gun to back up their missiles.
The Phantom has a phenomenal acceleration in takeoff when using the afterburners. It is exceptionally rapid. Despite the Phantom’s amazing take-off performance the pilot is in for an even more pleasant surprise when he receives an order to intercept an inbound target as soon as possible. The time required to accelerate from 0.85M to over 2M is truly remarkable and in my opinion places the Phantom foremost among the world’s fighters.
The tremendous power of the Phantom was used for a new style of dogfighting to counter the superior turning capability of the lightweight MiGs. The “energy maneuverability” was based on boosting a fighter up and down in yo-yo and barrel-roll maneuvers against classic horizontal turns
The Phantom pilots were taught to fly and fight in the vertical plane, with dives and zooms which the MiG pilots could not emulate. Consequently, the US success rate against the MiGs substantially increased. During Linebacker I and II, US fighters downed more than 50 NVAF MiG-21s, most falling to USAF F-4 Phantoms.
The Phantom has a higher thrust-to-weight ratio and superior high angle of attack performance against the MiG-21. Increasing your aircraft’s energy to a higher level than that of your adversary is very important. It provides a margin of performance and allows for more options, including getting away if you are jumped by a second enemy fighter. The base energy level of the engagement determines the extent to which maneuvering is accomplished in the vertical rather than the horizontal plane. Typically, the Phantom is maneuvered through a series of barrel rolls, performing what is commonly referred to as a vertical rolling scissors in order to cut down the angle-off and align the fuselage with the enemy’s in order to get a shot.
The Phantom introduced new concepts of maneuverability in the vertical plane. It offered, for the first time, enough surplus power to convert the combat arena from a horizontal plane to an egg-shaped field of maneuver in which the adversaries could adopt a whole new range of relative positions. The turn, climb, acceleration, and weapon characteristics had now to be analyzed to get the most out of them.
With that came the need for F-4 crews to have a thorough mathematical understanding of the interaction between the three-dimensional maneuvers and the performance capabilities of the aircraft. Such an analysis had to become second nature for the pilot. Later aircraft, like F-15, F-16 and F-18 have more advanced systems which do a lot of this work automatically, reducing the load on the crew. In the F-4 the aircrew must do most of the work. Success in air combat ultimately depends on aircraft performance and the crew’s utilization of that performance. In the F-4 much depends on the angle of attack – the angle of the wing in relation to the airflow past it. The Phantom accelerates, turns, and rolls best at different angles of attack. A too high angle of attack produces adverse yaw and can stall the plane. Stability augmentation, provided by electronic black boxes, helps greatly in keeping the aircraft under control at high angles of attack, and permits the pilot to maneuver in conditions of high buffet – structural oscillation caused by airflow breakaway – which would otherwise would force him to reduce the angle of attack.
Curiously, the F-4’s best fighting altitude against the low-wing-loaded MiG-17 and -19 is below 15,000 ft. Analysis revealed that at those altitudes the F-4’s energy maneuverability and weapon system combine for the best result. The F-4 has more excess power, better instantaneous and sustained maneuverability, better fuel economy, and more firing opportunities for the Sparrows and Sidewinders.
The Phantom had been designed to fight at long range, using its on-board radar to acquire a target, its Sparrow missiles first, with their 28-mile range, the idea being to hit the enemy at BVR – Beyond Visual Range, and, if that failed, its Sidewinders at closer range. Guided missiles signaled a major change in air combat, but they had not grown out of the tradition of fast moving, tight-turning, snap-shooting dogfights. They had been designed to hit bombers, and their limitations made them unsuitable for aerial combat between fighters. The requirement to visually identify any potential target, robbed the Phantom pilots of their main advantage as in the close-quarter battle the MiG was highly likely to be inside the minimum range for the Sparrow. Once they were in a violent close battle and the Phantom pilot was engaged in evasive maneuvers, which produced high g-loadings, there were no 30 seconds to 1 minute of stable flight to get a lock-on. And he had to fight on the enemy’s terms. Close in, what was needed was a gun, and the Phantom had no gun. Each pilot had a different agenda, looking for the best conditions for his aircraft and armament. The Phantom pilot’s repertoire included breaking away to put some distance between it and the MiG, then turning back into the fight with missiles ready. It could not match the MiG’s turning ability so getting in its 6 o’clock was difficult, but by rolling away from the MiG’s turn and pulling above it, keeping an eye on it all the time, then pulling through off the top of the roll, it could get on the MiG’s tail for a Sidewinder shot. In May 1967 the Phantom got a gun, not as an integral part of the aircraft – that would take longer – but in a pod slung along the fuselage centerline. It was an M61A1 Vulcan 20-mm cannon capable of firing 6,000 rounds a minute.)
Lt-Gen John Burns USAF (Ret) had a fighting career that started with piston-engined fighters of WWII and culminated with supersonics 25 years later. The F-4 is a favorite of his, but as fond as he is of the Phantom, Burns is aware of its bad points as well as its good. Gen Burns regards the F-4 as the premier fighter of the time, with good speed, payload, armament and thrust-to-weight ratio. It was a tolerant aircraft, easy to fly. This quality resulted from the thrust-to-weight ratio and the generous wing area. Two engines made flying safer and on many occasions pilots came back with one engine shot out while a problem with one engine never spread to the other one. The Phantom was very versatile and easy to switch from one mission to another as the need arose. When with a full bomb load, if the MiGs showed up, the ordnance could be jettisoned and the F-4 was then a first-rate air combat fighter.)
and this also Data for the Kfir
The Mirage IIIB which had been used to support the Mirage upgrade and Nesher development was again passed to Israel Aircraft Industries in April 1969 to serve as the test-bed for J79-GE-17 installation and the maiden flight followed on 21 September 1970. The mock air engagements between the modified trainer and Mirage IIIC fighters demonstrated the marked performance improvements gained with the engine installations.
While work continued to optimize the J79 installation in the Mirage IIIB, the project was considered sufficiently successful to manufacture the Nesher with this powerplant. A Nesher was modified to accept the American engine and it flew on 4th June 1973. The promised performance improvements were quickly demonstrated with the plane achieving the Mach 2.4 speed and 75,000 ft (22.860 m) altitude.
Israel Aircraft Industries took up this challenge with little hesitation and the prototype Kfir first flew on 7th August 1974. While the Kfir shared much commonality with the Nesher, it also incorporated numerous upgrades apart from the engine. Despite being a heavier aircraft, the greater thrust of the J79 more than compensated with excess power to benefit combat. However, a shift in the nominal center-of-gravity location produced an increase in the stability margin and the widened aft fuselage created somewhat higher overall drag, making the plane slightly less agile. These problems were addressed with the introduction of the canards aft of the inlets which improved high-angle-of-attack capability, reduced static margin for reduced trim drag, improved the stability margin for better maneuverability, enhanced sustained turning performance, provided for higher excess energy, a low gust response, stress relief in the wings with resultant increased fatigue life. Besides, a small strake was installed on each side of the nose and generated a desirable aerodynamic interaction with the canards. The strakes also further enhanced high-angle-of-attack performance (through reducing vortex shedding which caused an undesirable yawing moment at high angles of attack). In addition, the wings acquired leading edge sawtooth extensions for higher combat agility.
These changes added 85 kg to the Kfir’s empty weight but the extra lift from the canards allowed to increase the maximum gross weight to 14570 kg.
Typical combat weight with half of internal fuel and two Shafrir missiles – 9,390 kg.
Wing/canards loading at combat weight (9,390 kg) – 257.5 kg/sq.m.
Thrust/weight ratio at combat weight (9,390 kg) – 0.91.
Max rate of climb at sea level – 14,000 m/min.
Turn performance at 4,600-meter altitude and combat weight (9,390 kg):
Turn rate: sustained – 9.6 deg/sec; instantaneous – 18.9 deg/sec.
Turn radius: sustained – 1,326 m; instantaneous – 671 m.
“Shield of David” (1978) by M. Rubenstein & R. Goldman.
Israeli pilots test-flew the MiG-21, entering into mock combat with their own Mirages. The MiG-21 was found to be underpowered, though fairly maneuverable at high altitude. The MiG possessed excellent acceleration which was achieved through its small size and aerodynamic refinement rather than through a high-thrust engine. Its range was also very limited.
http://www.iaf.co.il/iaf/doa_iis.dll/Se ... 7.3.4.html
In August 1966, an Iraqi pilot defected to Israel in a late-model MiG-21F-13 (Fishbed-C). The IAF began studying the plane. The first to fly it was - who else - Danny Sha-pira, the IAF's veteran chief test pilot.
The systems in the cockpit were bulky and unwieldy. The pilot's view of the out-side world was almost completely blocked off, and turning his head sideways was difficult. The Russians believed that the pilot should look forward at all times.
In the air, Danny Shapira discovered that the MiG-21 was a powerful bird. When taking off simultaneously with a Mirage, the MiG shot ahead and accelerated better, in both subsonic and supersonic speeds. Its drawbacks became apparent at low-altitude high-speed flight: the high pressure on the rudders limited the plane's maneuverability, which - under those conditions - was not much better than a Piper's.
In the course of the test flights, Shapira gradually discovered the areas in which the MiG-21 could be outperformed by Mirages. He imparted his discoveries to pilots from the different squadrons, advising them to try and engage the MiG-21 in specific altitudes and speeds, which would put the MiG-21 at a disadvantage.
“No Margin for Error” (1993) by Ehud Yonay
On August 16, 1966, an Iraqi defector landed a MiG-21 in perfect working order on the Hazor tarmac and Dani Shapira, the IAF’s chief test pilot, took the MiG through every nook and cranny of its flight envelope. “We found out that at high speeds it had trouble maneuvering as well as the Mirage, which meant that we had to try to get it into tight turns at high speeds. Also, at slow speeds it had a tendency to spin out, and at tight turns at low altitudes it would snap and flick into the ground.” After completing his test series and writing a book on the MiG-21, Shapira began flying it alongside and against the Mirages. By the end of the year, each Mirage squadron was thoroughly familiar with every as-pect of what was heretofore the world’s most mysterious and formidable fighter.
“Israel’s Best Defense” (1993) by E. Cohen
When the Chief Test Pilot of the IAF, Danny Shapira got into the cockpit of the MiG-21 for the first time, he was surprised by a plethora of levers and buttons in an illogical order. It looked very inferior to the elegant Mirage with its ‘no hands’ flight. Iraqi Captain Muneir Radfa, who brought the plane to Israel from Iraq, agreed that the cockpit was uncomfortable and disorganized, but insisted that the plane was easy to fly. The first flight confirmed his words; it was easy. To Danny, it felt like the Mirage, but was a bit faster and had a lower peak altitude of 40,000 feet. When Danny began to maneuver, he discovered how the MiG differed from the Mirage. The MiG was difficult to steer at speeds over 500 knots. Danny had to use tremendous strength on the stick to steady the plane in turns, especially in sharp ones. At greater speeds the danger increased. The nose and the right wing pulled downward. Since the back of the cockpit was obstructed, the pilot’s field of vision was severely limited. After many dogfights, Danny concluded that in terms of handling, the MiG-21 was even with the Mirage.
“Air Warfare in the Missile Age” (1985) by Lon Nordeen
The Israelis highly rated the MiG-21 as a medium-altitude dogfight aircraft. With its slightly higher thrust-to-weight ratio and lower wing-loading, it was able to out-accelerate and out-turn the Mirage IIIC. Nevertheless, the Mirage’s pilots managed to shoot down MiG-21s as Arab pilots generally did not fly the plane to its limits of performance.
However, the MiG-21 was found to be highly susceptible to battle damage, having a tendency to burn or explode after being struck only a few times with 30-mm cannon fire. On the opposite, a Mirage was hit by the Soviet-built Atoll infrared-guided air-to-air missile fired from an Iraqi MiG-21 over an Iraqi airbase where the Mirage was patrolling. The Mirage’s tailpipe suffered extensive damage, but the pilot was able to return to the base.]
Peebles, Curtis. Dark Eagles. Novato, CA, USA: Presidio, 1995
Capt. Monir Radfa, an Iraqi pilot, took off from Rashid Air Base outside Baghdad and landed at Hatzor Air Base in Israel on August 16, 1966, with his Mig-21F-13. For the next several months, it was subjected to a series of flights to learn its strengths and weaknesses. These were made by Lt. Col. Dani Shapira, the Israeli Air Force’s chief test pilot. He recalled later: “We found out, for example, that at high speed it had trouble maneuvering as well as the Mirage, which meant we had to try to get it into tight turns at high speeds.”
At low speeds, the Mig-21 would tend to spin out in tight, low-altitude turns. The Mig-21 was then used to train Israeli Mirage pilots. Some 100 hours were spent flying in mock combat with Israeli Mirages. By the end of the year, every Mirage squadron had been familiarized with the Mig-21.
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MiG-21: Its delta wing allows it to turn very well, but the induced drag of that configuration ‘bleeds’ energy rapidly and when MiG-21 turns, it costs. So the trick is to get the MiG-21 down to an altitude below 20,000 feet. That’s where the Phantom really performs well with its wing; it turns and accelerates well. But if you get above 20,000 feet and tangle with a MiG-21, he will chew you to pieces because of the advantages of his wing and his speed.
Steve Ritchie, a Phantom ace, considers the MiG-21’s speed and turning ability to be excellent, but the MiG has roll rate troubles at maximum speed, as well as longitudinal stability problems.
The delta--wing design of the Mig-21 also loses energy in turns faster than the F-4 does and the Mig has a tendency to lose speed in turns.
“Aircraft vs Aircraft” (1986) by N. Franks.
Full-afterburner thrust:
MiG-21 -- 13,117 lb.
Mirage 3C -- 13,670 lb.
The MiG-21’s delta-wing configuration gave it poor lift at subsonic speeds.
In a high-angle-of-attack situation, the MiG-21 bucks about almost uncontrollably and can only be pointed rather than aimed.
“The Threat” by Cockburn.
The handling of the MiG-21 was bad. U.S. pilots who flew the 12 MiG-21s presented to the U.S. by Egypt in 1978 reported that below 15,000-feet altitude, where the air is dens-er, the control stick becomes very difficult to move: “Like pulling on a telegraph pole” was one comment. The cockpit visibility was extremely bad.
“Modern Fighter Combat” (1987) by Mike Spick.
The MiG-21 design is based on tailed delta wing planform while the French Mirage was a tailless delta. The pure delta has many advantages in high-altitude, high-speed flight. It also has no clearly defined point of stall and develops max lift at very high angles of incidence. But it pays a high price in increased drag. Drag is also high while maneuvering.
The tailed delta avoided the worst drawbacks of the tailless variety.
Turning ability of the MiG-21 is good and at the lower speed levels it is very good. But increase speed to Mach 0.9 at 15,000-feet altitude and the MiG-21’s instantaneous turn rate becomes worse than that of the Phantom though still better than the Mirage 3C can achieve.
The controls are heavy, to a degree where a fair amount of muscle is needed. The pilot’s view out is not good, rear vision is almost non-existent and even the view ahead is restricted by both avionics displays and a heavy canopy bow. A fairly low fuel fraction reduces the combat radius without external fuel to a ridiculously short distance. The performance above 20,000 feet was described as poor.
The truth is that the MiG-21 is a very ordinary fighter and had it been of Western origin, it would have probably sunk without trace prior to 1970.
At the same time, the latest MiG-21bis (Fishbed-N) has a more powerful engine and a far superior thrust-to-weight ratio. Its performance has to improve dramatically and it must be a formidable dogfighter.
http://forum.keypublishing.co.uk/showthread.php?t=65706
) por el 98 o más adelante ( creo).
