The life of France’s greatest aircraft designer and manufacturer, Marcel Dassault, née Marcel Bloch in 1892, is a great story in itself and well worth a Hollywood movie. He was an aviation pioneer before World War I, already famous for having designed and built the propeller for the WWI Spad fighter, and later on for building a company that designed and manufactured more than 20 different types of aircraft between the wars. Just before the start of World War II, he designed the best fighter France had to oppose the Luftwaffe, the Bloch 157, powered by a surprisingly powerful Gnome-Rhône engine, that flew for the first time in 1942. Only one exemplar of the type was built and it was eventually seized by the Nazis and transported to Germany for testing. As can be seen here (with German markings), the 157 looked remarkably like a smaller and sleeker P-47 Thunderbolt. Marcel Bloch himself was sent to the Buchenwald concentration camp, where he remained a prisoner until the end of the war because he refused an offer of liberty on the basis of working for Germany.
After the war, Marcel Bloch returned to France, changed his last name to Dassault (which was his brother’s alias during the resistance) and became a living legend. The reason was a series of fighter aircraft that culminated in the Mirage III jet fighter, an unprecedented export success for French industry mainly due to the legendary feats of the Mirage III-equipped Israeli Air Force during the 1967 war. It flew for the first time in November of 1956 and was the first European aircraft to exceed Mach 2 on level flight, in October of 1958. See the Australian Mirage III-O specs here and a profile of the Spanish Air Force IIIC version here.
France was behind the United States and Great Britain in aircraft design at the time, but that wasn’t going to stop Marcel Dassault from building a first-line, world-class fighter plane, and the Mirage III was the result of his ingenuity and resourcefulness. His design choices said a lot about the state of nineteen-fifties French aeronautical knowledge and about Avions Marcel Dassault’s limited research and development. The dart-like, full-delta profile was a clean and sleek design in which form followed function with beauty as its outcome, in the best tradition of Reginald Mitchell’s Supermarine Spitfire and Sydney Camm’s Hawker Hunter. The basic rightness of the original design is exemplified by its continued development, up to the Dassault Mirage 2000 that was built until the end of 2007.
But when you see the Mirage III up close you begin to notice the corners Dassault had to cut to build it. On the one hand, the full-delta wing gave the airplane good acceleration at high subsonic and transonic speeds and also provided high internal volume to store fuel. On the other hand, a delta wing means a high angle of attack and lack of maneuverability at low speeds. These shortcomings can be mostly overcome by way of appendages such as moving surfaces on the wing’s leading and trailing edges, but Dassault did not use them on the Mirage.
Both the cleanness of the design and the technological corner-cutting can be shown in what the airplane did not have: no landing flaps of any kind, not even the simplest ones, and much less a complex flap design such as a Fowler or slotted type. The design didn’t even allow for passive leading-edge slats, something the older North American F-86 Sabre and even the much older Messerschmitt Bf 109 both had! The result is that the Mirage’s approach and landing speeds, and its angle of attack at low speeds, were all quite higher than those of a comparable fighter with built-in landing aids, and it sorely lacked low-speed maneuverability.
These design choices (or forced constraints) meant, in practical terms, that the pilot had to compensate for their absence. While the airplane was a swift and beautifully handling platform at high speeds, below 300 knots it was a pig. And the pilot noticed the difference when first climbing out after takeoff: once it hit 400 knots, it became a nervously quick Ferrari at full chat.
For the same reasons, the Mirage III was also difficult to land and could be downright dangerous if the pilot wasn’t on top of it throughout the entire landing phase. You had to maintain a minimum of 200 knots indicated air speed (plus a few more to compensate for any residual fuel load) on the continuous 180-degree turn from downwind leg to final approach. Dropping below this speed (going below the power-to-drag curve) before final approach was an absolute no-no, due to the huge amounts of drag developed by the high angle of attack of the delta wing and also, to a lesser degree, because of the aircraft’s relatively slow response to pilot input. During this entire phase, and especially when flying an instrument approach, there was no constant power setting that would maintain a particular airspeed at a particular attitude, and therefore the pilot had to keep moving the throttle continuously, slightly back and forth, in order to maintain the required speed. The aircraft’s rapid rate of descent just before landing made it extremely difficult to predict where exactly it would land, so you had to give yourself the slack of a few feet behind or ahead of the patch of ground that was your intended landing target. A bad approach could end up with the airplane landing on the rough strip before the runway, with the consequence of damaged landing gear and blown tires. As an instructor pilot, landing a two-seater Mirage III from the rear cabin at night was an extremely difficult venture due to the almost zero forward visibility.
Another peculiarity that I remember well: the Mirage III had a clever and helpful hydraulic-powered automatic pilot system called Autocommande that helped to lower the high aerodynamic forces on the controls at high speeds and that maintained the last selected position of the control stick. This system was good for minimizing the aircraft’s sharp pitch-up movement when going transonic (due to the shockwave moving over the elevons), thus helping enormously when dogfighting, and it was also priceless for skinny pilots like me (all of 125 pounds sweat-soaked). The system, however, was also prone to unexpected failure, a lethal danger when maneuvering at high G’s at low altitude, and it was the cause of several major accidents in France. It was not to be used at low altitude in combat training, period. With it turned off, however, I developed my own way of handling the beast, using both hands on the control stick to be able to pull just enough G’s to keep abreast of the competition. Furthermore, if you dared to maneuver on full afterburner at low altitude without Autocommande, you had to keep your mind and hands well ahead of the airplane, or it would certainly get ahead of you and go skidding through the air in a most spectacular and hairy way! Imagine yourself in a rodeo riding a fast, wild mustang that is busily trying to get rid of you, and you have the idea.
A simple Mach 2 practice run would proceed like this. With a clean airplane, that is, carrying no outboard pylons or loads of any sort, you would climb out at 100% dry power (no afterburner) on the same heading of the runway until you reached 40,000 feet, which took less than 4 minutes from the start of the takeoff run. A 90-degree right turn followed by a 270-degree left turn would have you heading back toward your base of origin. You would then set minimum afterburner on, check exhaust temps and stable exhaust clamshell opening, then set full afterburner and leave it there for the remainder. The sleek delta wing permitted a fast transition from subsonic to supersonic speed and a sustained acceleration to Mach 2. The airplane was so aerodynamically clean that its top speed was limited only by the outside temperature. That is, the Mirage wanted to keep going beyond Mach 2, but you had to throttle back as soon as a big red light (plus a warning beep on the headphones) told you the sensor indicated that the outside impact temperature had reached 155 degrees C. Why the temperature limit? In the stratosphere, depending on the season, outside temperature normally hovers around minus 55 degrees C, but an aircraft flying through it at supersonic speed gets very hot due to air friction. A temperature higher than 155 degrees would cause “heat creep,” which meant that the impeller blades of the compressor located at the front of the SNECMA Atar 9 engine would get so hot that they would begin expanding longitudinally, eventually scraping the interior of the engine duct. A flying bomb, anyone? At the end of the high-speed run you would be near enough to the air base where you took off from, and with such a low fuel load, that a fast high-altitude jet penetration for landing was in order. Total flight time? About thirty minutes. A sortie like that would only be done when intercepting high-flying enemy bomber planes.
A shorter, faster and riskier experience was a ground radar-guided head-on interception of a high-flying Mirage IV (the scaled-up French nuclear bomber). During a mission like that you were on full afterburner from takeoff to the end of the interception at 40,000 feet or above, when your speed would have hit at least Mach 1.4. Even the practice dry runs, with no opposing airplane to worry about, were difficult and scary enough: just imagine the absurd combination of my foreign accent, my French instructor on the back seat, several French air intercept (GCI) ground controllers, plus a few other NATO pilots from West Germany or Denmark also training in the vicinity, all trying to speak English. For whatever reason, a modern version of the terms that British pilots and controllers had developed for the Battle of Britain in World War II was used by NATO everywhere in Europe during interceptions. Yes, it was difficult to understand what anybody was saying.
The fastest I ever flew was Mach 2.05 (about 1,354 mph) at 40,000 feet. This was in Venezuela, close to the Equator; cooler climates in Europe allowed for top speeds of up to Mach 2.15. The French Air Force Mirages could use (but almost never did) a rocket booster intended for intercepting the highest-flying Soviet aircraft of the time, that pushed the Mirage’s altitude capability to 60,000 feet. The pilot had to wear a special, fully-pressurized astronaut-like suit that I only saw in pictures.
Dassault owed quite a lot to the Israelis for the airplane’s development, for they were the ones who discovered and got rid of the initial bugs of the Mirage the hard way, dogfighting with Syrian MiGs above the Golan. For example, the 30 mm. DEFA cannon at first did not shoot straight and also caused engine stalls when shooting at extreme flight attitudes. I still remember French aviation officers never admitting the problems even existed.
Last but not least, I will describe one little trick that I learned by chance and that I fully exploited to my advantage until somebody else discovered it. All pilots know that the flight manual is a Bible and a Merriam-Webster at the same time, and hardly any pilot reads anything else regarding his airplane. Fresh from the course that I attended in France together with other four Venezuelan pilots and wanting to learn as much as I could about the Mirage, I also studied the airplane’s maintenance manuals. One day I found in one of the manuals a short instruction on how to ground-test the engine that clearly contradicted our pilot’s flight manual in one very important point: It read that, for testing purposes, one could turn the afterburner on, in its minimum position, against the brakes.
The Mirage pilot flight manual (probably to avoid an underperforming set of brakes causing damage to the tires if the airplane slid forward with locked wheels) clearly stipulated that, to begin the takeoff run, the pilot should set full 100% dry power against the brakes; he then should, at the same time, let off the brakes and set minimum afterburner power; only then, after making sure everything was well with the engine, would he apply full afterburner power. Although the procedure took less time to do than what it takes you to read this explanation, it obviously extended the takeoff run because part of it was done while the airplane was already moving forward.
My trick was to do the following during daytime only, so that the afterburner exhaust flame could not be seen behind the airplane from a distance, thus not giving me up. After making sure my plane had good brakes, I practically locked my extended legs in order to exert maximum pressure on the brake pedals; I then carefully applied minimum afterburner and, after the required checks, quickly pushed the throttle forward into full afterburner while letting off the brakes. The results were that I consistently took off in significantly less distance than any other Mirage pilot. This astounded everybody in our airbase and it was surely a heavy burden on the other pilots’ egos. I remember noticing that lots of people were always outside the Air Group buildings watching my single takeoffs (the runway was some distance away), but few ever told me they did that. All kinds of theories were put forward as the cause: one was that since I was so skinny, the cause was the lower takeoff weight of my airplane; another was that I had a special “feel” in my hands that no other pilot had (I liked this one), and on and on.
The good old times.
Vladimir Dorta, April 22, 2003