Type 791B Aircraft Cannon - Archived 2/2000

Outlook

Orientation

Technical Data

The reliability of the Type 791B is stated by the contractor to be 13,000 mean rounds between failure.

Variants/Upgrades

Not applicable at this time.

Program Review

MG213C Principle. The basic operating principle of the revolver cannon MG213C is that the weapon’s feed operation is split into three separate and consecutive actions. These actions are stripping the next round from the link; feeding the round via an oscillating rammer into one of five chambers in the revolving cylinder; and the presentation to the barrel, located at the 12 o’clock position, again a function of the revolving of the cylinder. The ammunition belt was fed in via belt feed sprockets which rotated in unison with the cylinder. After firing and another movement of the cylinder, the case is ejected to the rear, again via the oscillating rammer; the cannon was gas operated. The initial cocking of the cannon was achieved by a pneumatically operated mechanism; firing was electric. To the Germans at that time, the revolver operation not only speeded up the cannon cyclic rate, but reduced velocities and moments on the various internal components of the cannon. This allowed for the use of inferior materials as high technology alloys were becoming increasingly scarce in Germany at that time. In any event, the MG213C soon became a highly respected weapon among Allied airmen who had to face it; the 1,200 round per minute firing rate of the 30 millimeter cannon had a devastating effect on any aircraft.

Following the war, the Allies scrambled to acquire and evaluate the German technology which had recently given them so much trouble. The MG213C was included in the mass of war booty and examples of this splendid cannon were soon being tested in the United Kingdom, France and the United States. In the end, the MG213C was considered so good that every other aircraft cannon had been rendered obsolete overnight. If imitation is the sincerest form of flattery, then Politzer and Mauser must have been smiling as all three Western Allies decided to copy the MG213C for their own use. The United States did try to change the design enough to say it had been enhanced, but all the Americans did was change the caliber to 20 millimeters (the Germans also used a lesser-known version of the MG213 in the 20 millimeter caliber) and move the barrel to the six o’clock position. These design changes were accomplished by the Illinois Institute of Technology. Following design and testing of the cannon, known as the M39, it was placed into serial production, initially by Ford Motor Company and ultimately by the Pontiac Division of General Motors. Despite the advent of General Dynamic’s Vulcan cannon with its phenomenal rates of fire, the M39 remained in production for some four decades, serving on later models of the F-86, F-100, F-101, and the ubiquitous F-5, the production of which finally ended in 1988.

The French and British were less timid in their copying of the MG213C; the British cannon, the ADEN is an almost direct copy of the MG213C. The French also copied the MG213C cannon; it is possibly used on even more types than the popular ADEN. In the late seventies, Giat Industries, the umbrella French arms development and manufacturing organization, began the effort to significantly enhance performance of the MG213C revolver cannon principle.

Analysis of the requirements for a new 30 millimeter cannon revealed that the first thing that would be required was a new family of 30 millimeter ammunition. The popular 30 millimeter ADEN/DEFA ammunition was originally developed in the late 1940s, and ammunition, particularly propellant technology, had progressed far beyond the technology employed in those rounds. The then-Matra Manurhin Defense was assigned the task of developing the new family of 30x150 ammunition in a number of types.

The task of modifying and developing a greatly enhanced version of the basic MG213C technology proved much more difficult. Already, the design had been greatly refined in the 552A, 553 and finally the 554 cannon. The British had enhanced the firing rate of the ADEN by going to the new more powerful NATO standard 25 millimeter ammunition; the cyclic rate of the new ADEN 25 is 1,850 rounds per minute.

In the original MG213C design, the round is separated from the carrier link before it is fed into the weapon. The French computer aided redesign of the weapon strips rounds from the carrier links before they are fed into the weapon. This reduces the number of parts in the cannon, plus reduces the risks of jamming to almost nothing.

The French also designed the new cannon to be fed from the left or the right, greatly aiding in the integration of the new cannon with various types of aircraft. The spent cartridge cases are ejected to the rear and collected in a case which is mounted on an extension of the breech assembly. The new cannon also employs an automatic recocking device for use in the event of a misfire. While gas operation is retained, a new electric ignition system contributes to the reliability and safety of the cannon.

Since French studies of aerial combat indicated that the 2,500 round per minute cyclic rate was not always needed, the designers allowed for the Type 791B rate of fire to be instantly changed by the pilot to 1,500 or 200-400 round per minute rate.

The first pre-production Type 791B cannon found its first home in 1988 on a developmental prototype of the new Rafale aircraft, France’s contender for the Multi-national European Fighter Aircraft program. Even though the Rafale was not selected for this program, it has a secure place on the Rafale, France’s next-generation fighter aircraft.

Funding

Development funding for the Type 791B cannon has come from the French Ministry of Defense through the French Air Force.

Recent Contracts

Unavailable, as contractual information is not released.

Timetable

This table is applicable to the Type 791B cannon only.

Worldwide Distribution

Forecast Rationale

Again this year, in the conduct of research on the Type 791B cannon, we have reduced the number of developmental prototype Type 791B cannon produced to date. As of early 1999, the low-rate initial production of the Type 791B is ongoing in order to address the demand for the Rafale aircraft. For the present, this is the only application for which we are forecasting production of the Type 791B. However, we will continue to monitor this important program and update this report on an interim basis if new developments warrant. In the forecast chart below, a ten-percent spares factor (including complete cannon and components thereof), and a nine-month lead time, are worked into the forecast.

Ten-Year Outlook