The secret flying suit

Legion magazine March/April 2017

In 1939, driven by the demands of World War II and the advent of combat aircraft that flew higher, faster, and manoeuvred more tightly than ever before, a top secret aviation research facility was opened by the RCAF in downtown Toronto in what used to be the Eglinton Hunt Club.

One of its priority projects was to find ways to prevent pilot blackout during high-G turns and dive pullouts. Led by Dr. Wilbur Franks, a colleague of Frederick Banting at the University of Toronto, the world’s first G-suit was designed and tested. It was a simple idea: when a pilot experienced Gs, the suit would force water—later compressed air was used—into bladders to constrict the body, forcing blood upward and helping to maintain consciousness. Despite having never flown in an airplane, Franks personally undertook its initial air testing. It was dubbed ‘The Franks Flying Suit’.

G-forces are experienced during sharp aerobatic manoeuvres such as steep turns, loops, and pullouts from dives. Measured as multiples of gravity, the higher the number the greater the forces draining the blood from a pilot’s upper body. Up to 2 G is felt but there’s little physical effect. At 3 G vision dims. Between 4 and 6 G total blackout occurs, progressing to loss of consciousness. And Spitfires and Messerschmitt 109s of the time had the power to sustain up to 7 G in a turn. Clearly if the G effects could be counteracted, Allied pilots would have a distinct edge in dogfights.

In 1939 Franks accidently found a way while conducting cancer research using a small lab centrifuge. He discovered “that mice, when suspended in a fluid the specific gravity of which approached that of the mouse’s body, could withstand, without apparent damage, over 100 times the normal gravity.” He thought, why wouldn’t the same principle apply to humans? In humans, he reckoned, the water would exert pressure against the lower body and prevent blood from pooling in the calves, thighs and abdomen under high-G forces. He set out to design a wearable water-filled suit that would do just that.

His design concept was relatively simple. The suit would need two layers, with the fluid contained between them. Importantly, the outer layer would have to be non-extensible and the inner layer, extensible, because the purpose of the suit was to direct the fluid inwards against the pilot’s body. So under high accelerations, the fluid pressure against the lower extremities would prevent the pooling of venous blood.

With the help of a T. Eaton Co. tailor, the first suit was stitched together in Franks’ university office using rubber material supplied by Dunlop and bootmaker Gutta Percha Rubber Company. It was tailor-made for Franks and covered his body from neck to toe. He soon suited up and strapped into a Fleet Finch biplane for some aerobatics at Camp Borden in early 1940 to see if the invention would work as planned. It did, but after experiencing 7 G pulling out of a power dive he reported, “I thought it was going it was going to cut me in two.” He quickly realized the problem: “the rubber enclosed fluid system need only cover selected portions of the body to have the system effective.”

The suit was modified to cover just the lower body, and the next tests were a series of top secret flights by RAF Wing Commander D’Arcy Grieg in a Spitfire at Malton Airport June 2nd to 5th, 1940. After a program of aggressive manoeuvres with no blackouts, Grieg’s report to Air Force HQ stated that the suit “in its present form is not a practical proposition. However the results obtained were of such a convincing nature that further development is strongly recommended…”

Encouraged, Franks figured without readily available test aircraft, extensive development could best be done in a full-sized centrifuge. With a $25,000 grant from the National Research Council in June 1940, a centrifuge was constructed in the old Hunt Club building.

Progress quickly gathered momentum. In April 1941 Franks took his revolutionary suit to the Royal Aircraft Establishment at Farnborough, England, the centre for RAF aviation medicine, to demonstrate it. There, the RAF flight tested his invention aboard Fairey Battle and Hawker Hurricane aircraft and it “was found to prevent blackout up to 9 G.” That summer, in an RAF report entitled “Tactical Trials with Hydrostatic Flying Suit” its benefits were summarized: “In combat the wearer of the suit can follow his opponent however sharply he turns and still retain his vision which will enable him to use his sights. In the pull-out from a high speed dive at low level a protected pilot will be able to force a following opponent to black out or break away.”

Meanwhile, the Americans were taking note too. Several USAF pilots were fitted out with early Franks Flying Suits and a representative of the Dunlop Company went to Wright-Patterson air base to oversee the project. Flight tests began in April 1941. One of these tests pointed up a caution to using the G-suit: overconfidence caused by lack of ‘seat-of-the-pants’ feel. The first fatal accident involving a G-suit happened here when USAF Lt. Carleton overstressed a Curtiss P-40 during testing and the aircraft broke up in the air.

The effectiveness of the Franks Flying Suit had been well-established by August 1941, just a little more than a year after its first flight tests. But so far it was entirely a scientific experiment. It remained to be tested operationally. Would the suit prove itself in the heat of air combat? That would soon be answered.

By November 1942, on the strength of the testing at Farnborough, Air Chief Marshal Douglas of RAF Fighter Command was ready to commit. He reported, “I have reached the conclusion that a pilot wearing this suit has an important operational advantage over a pilot not so equipped…I therefore favour the adoption of the Franks Suit for operational use.”

Meanwhile, the Royal Navy had beat him to it. It was already battle-testing the G-suit, flying off the carrier HMS Furious, during the Battle of Oran in the Mediterranean. Fleet Air Arm Seafires provided the only fighter cover for General Eisenhower’s invasion of North Africa in November 1942, and it was there that the Franks Flying Suit became the first G-suit in history to be used in combat operations. The Royal Navy pilots loved the new invention, reporting greatly enhanced ability to manoeuvre and outfly the enemy without experiencing blackouts. Some mentioned a bonus: a week’s supply of fresh drinking water in the event they were forced down.

But the RAF decided to limit its use, despite having stockpiled more than 6,000 units. They were keen to preserve its secrecy until it could be used to greatest advantage in the invasion of Europe.
Top brass feared early use of the suit would risk its capture by the enemy, and once captured could be quickly duplicated, negating an Allied tactical advantage. So the Franks Flying Suit was held under a top secret classification and usage restricted to operational testing until it could be introduced all at once for a large-scale European invasion.

It turned out they had little to fear. According to George Smith, who researched the development of the Franks Flying Suit for his MA thesis at the University of Western Ontario, German researchers had been working on anti-G suits since 1935. In May 1939, Siegfried Ruff had outlined their findings: The fluid-filled suit was not practical. The German suit had been deemed impractical because of the weight and bulk of its fluid. In Ruff’s judgement, Smith reported, the “weight of the suit alone, as well as the hindrance to the movements of its wearer…interfere with its effectiveness.”

And indeed, the fluid-filled suit was beginning to lose favour with the Allies too, later in the war. By the time the Franks suit was being operationally tested and mass-produced, the air combat environment had changed since the first years of its invention. The initial years of the war involved much more air-to-air fighter combat, for example the Battle of Britain. But by 1944, more and more fighter squadrons were being assigned long range fighter escort duties for daylight bombing raids. That meant minimal dogfighting and fewer high-G manoeuvres. Instead, the norm was six to eight hours of slow cruising alongside bomber formations. Many Spitfire and Mustang pilots who evaluated the suit in this newer role complained about its discomfort on long missions, the inability to relieve themselves, and the lack of space in the cockpit.

Moreover, when they did have to engage enemy fighters, pilots were up against an evolutionary change in tactics. The surprise attack, usually ‘bounced’ from the rear, had become the most deadly: at least 80 percent of fighter pilots shot down never saw their attacker. So alertness and good visibility, especially to the rear, were of major importance in dogfights.

It was becoming evident that the only way to alleviate the discomfort and restriction of the suit would be to eliminate use of a fluid. Air had been considered in Franks’ early years, but on prop-driven fighters that would have meant installing extra equipment like a compressor, sapping engine power.

In 1944 American research was underway at the Aero Medical Laboratory in Dayton, Ohio to develop an air-filled version of Franks’ original suit, using compressed air instead of water. Named Type G-3, it employed five air bladders covering the calves, thighs and abdomen and weighed under a kilogram. It was activated only when forces exceeded 2 G. For normal flying, the suits were entirely comfortable as they inflated automatically, and only when it became necessary.

The timing was good. Later in the war, jet fighters first took to the skies in combat. They offered sufficient extra power to supply air to the suits—directly off the jet engine’s compressor stage. Which was convenient because the need for anti-G devices is more critical in jet fighters: it’s easier to pull high G. It was really the arrival of the jet fighter that brought Franks’ invention into everyday use.

And more. In a 1983 article published in The CAHS Journal, writer Peter Allen said a major factor was Canadian researchers sharing their findings internationally. “There was a lot of research into ways to deal with acceleration but none of them worked. Franks’ suit was the first that worked. After Franks’ discovery was provided to them, everybody got in the game but it was because of Franks’ original discovery that they were even in the game.”

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