Arie Egozi/TEL AVIV
THE UPGRADE prepared by Israel Aircraft Industries (IAI) for the MiG-21 (Flight International, 15-21 March, P14) has been driven by the assumption that most potential customers want to enhance the aircraft's capability, but have a limited budget with which to do it. The guideline to the designers has therefore been clear - keep as many as possible of the original systems, but enhance the overall combat capability.
While engineers studied the various original systems in the early days of the programme, test pilots went to Eastern Europe to fly the MiG-21 in its "natural habitat", and according to the operational doctrine dictated by the former Soviet Union. "We were surprised by the limited freedom the pilot had when flying these aircraft, and by the total reliance on a ground station telling him where the targets were and how to approach them," says IAI test pilot Ronen Shapira.
The original cockpit of the MiG-21 reflected, along with poor human engineering, the concept of leaving little to the pilot's discretion in combat flying. The three-piece, view-obstructing windshield, the enormous number of switches and the poor display of the radar could result only in a very uncomfortable pilot eagerly waiting for instructions from the ground.
IMPROVED VISIBILITY
A one-piece windshield is the only external change in the upgraded MiG-21. Not only does it improve dramatically the view of the outer world, but modern technology has eliminated the need, to use alcohol based anti-freeze.
Inside, the cockpit has been totally redesigned. A head-up display (HUD) and multi-function display (MFD), are the most distinct changes. The power behind the cockpit systems is an R-3000-based mission and display processor, which also controls the 1553B databus interface. The computer, manufactured by Israeli-based Astronautics, not only drives the displays, but supports the improved navigation system and manages the air-to-ground and air-to-air weapons, carried under the wing.
The HUD has been developed, by Israeli manufacturer EL-OP in Israel, for use in small and medium-size cockpits. It is capable of displaying high-brightness stroke symbology, with an option of overlaying it on a raster display.
The main means of navigation is by an Israeli-made inertial-navigation system (INS), aided by a C/A code global-positioning system. According to Shapira, this combination results in excellent accuracy. He says that, before a mission, the INS is aligned in less than 2min. "After a 30min mission, the system deviation is no more than one-tenth of a mile [160m]," he adds. The improved navigation system allows the MiG-21 to be landed in a visibility of 200ft (60m).
While new radars are offered as options to potential customers of the upgraded MiG, improving the output of the original Almaz radar system is probably going to be a best seller. The data gathering of the radar has not changed, but its signals are now processed by the main computer and then displayed on the MFD in a way, which allows the pilot to use it better in combat situations. "For a fraction of the price of a new radar, we have improved the performance immensely," says Shraga Bar-Nissan, general manager of IAI's Lahav division, where the upgrade has been manufactured.
The upgraded prototype aircraft has undergone six successful test flights, and the integration of the improved radar with the other systems is about to begin. The old radar is a limiting factor on achieving total pilot-freedom during missions. Such a freedom is achievable by installing a multi-mode pulse Doppler radar, but Bar-Nissan says that many of the potential clients are settling for the intermediate solution. Further improvements to the existing radar are planned, but IAI is reluctant to reveal exactly what they will be.
The elimination of most of the original switches in the cockpit is part of the plan to implement a hands-on-throttle-and-stick concept. The greater independence of the pilot is also a result of the way in which the data are displayed on the MFD. The map and intelligence information, for example, is displayed when required by pressing a set of select switches. Another system, to enhance tactical awareness and navigation accuracy, has been installed in the first prototype, but IAI refuses to elaborate.
An additional tool for enhancing the pilot's independence is the joint high-accuracy positioning system. This tactical datalink allows the aircraft to communicate with other aircraft by relaying radar targets, threats and relative location. The pilot of an advanced fighter, with modern radar and sensors, can use the system to "feed" the MiG-21 with important data. "This datalink is secure in aircraft-to-aircraft and ground-to-aircraft datalinking," says Hillel Shacham, the programme's marketing manager.
ADVANCED WEAPONS
The powerful mission computer drives an advanced weapon-release system. It enables computerised control and release of new Western-type weapons such as third-generation infra-red-guided air-to-air missiles. The system also enables the MiG-21 pilot to use automatic blind attack, as well as continuously computed impact point and dive-toss visual bombing methods (where a weapon is released in a pull-up, following completion of a dive). The original armament-release system is kept as backup.
The improvements in the navigation and weapon-release systems have given the MiG-21 pilot a capability to locate the target and hit it at the first attempt. "This is important in any combat aircraft, but even more important in a combat aircraft so short on fuel," says one of the programme's test pilots, who is impressed by the manoeuvrability at high Gs.
The cockpit displays in the MiG-21 are in metric units. In the upgraded aircraft, the pilot will have a choice between this system and another, which uses Imperial measurements.
A small, low-cost, video-tape-recorder system has been installed in the left side of the redesigned cockpit. The cassette with HUD and MFD data, is taken by the pilot after landing, for immediate debriefing. In the original configuration, the MiG-21 is equipped with one communications transceiver. IAI has replaced it with two systems, to allow undisturbed communications between the pilot and the ground control, and between the pilot and other pilots.
The price tag on the MiG-21bis upgrade in the current configuration is about $1 million. It may reach $1.5 million, according to the options selected by the customers. This is a minimal package, which includes the original radar and some other systems. Some of the customers need an extra service - refurbishing the Russian-made fighters, which in many cases are grounded or limited in their operational capability, mainly because certain spares are missing. Experts from Lahav have combined all the code numbers, which the Russians used on the spare parts of the fighters, which were sent to different countries. This enables the Israeli Company to purchase spares from different sources.
IAI concentrated first on the bis upgrade because its production numbers were the largest. According to an IAI survey, more than 500 MiG-21bis will be kept in service in the coming years, and e could be candidates for upgrading. The Lahav division is now working on adding more features to the upgrades, including efforts to increase the maximum take-off weight.
Source: Flight International
