A Big Miss? The Gloster F.9/37

February 29, 2024

When you look at the primary fighter aircraft that the Royal Air Force (RAF) started the Second World War with in 1939, one really does look like an anomaly; the Gloster Gladiator.

Very much an aircraft from a previous era to its illustrious stable mates, the Hurricane and the Spitfire, the Gladiator in fact entered service less than a year before the Hawker Hurricane and only eighteen months before the Spitfire! And though the Gladiator gave solid service during the first years of the war, it was obvious from the start that it was verging on obsolescence and would need to be replaced in front line service in short order even as it joined RAF squadrons.

This all might give the impression that the Gloster Aircraft Company was somewhat conservative in their designs, a manufacturer that was hindbound to older aircraft philosophies and thinking. In fact, nothing could be further from the truth, and Gloster was in fact extremely innovative in their design practices and innovation; it’s just that this fact never got to be demonstrated until later in the war.

And today’s subject gives a perfect demonstration of the sort of cutting-edge aircraft Gloster could have been producing from the beginning of the conflict if things had turned out a little differently.

The Gloster F.9/37.

A fast, agile twin engine heavy fighter, the origins of this aircraft go back, rather bizarrely, to a British requirement issued in 1933 for a new two-seat turret fighter to replace the Hawker Demon. Gloster began development of a twin-engine design for this, but ultimately that came to naught when the Air Ministry changed their requirements a couple of times and eventually the Boulton-Paul Defiant was chosen instead.

However, Gloster’s efforts weren’t wasted when a fresh requirement was issued in 1937 for a twin-engine heavy fighter that should have excellent performance and heavy armament.

Late in 1936 the Dutch Fokker company had revealed their new G.I aircraft at the Paris air salon; a truly formidable heavy fighter that caught the attention of the world’s air forces and got a lot of design teams scurrying to develop their own equivalents.

But while other countries heavy fighters also went with two-seat layouts, which imposed limitations on performance because of the extra weight, Gloster mirrored what Kurt Tank at Focke Wulf in Germany was doing at the same time with the FW 187; they built a single-seat, comparatively light but heavily armed fighter. And apparently it was as fine an aircraft of its type as any other; indeed, it was far better than most.

The F.9/37 was built using an all-metal, stressed skin construction throughout, with only the flaps being fabric covered.

Additionally, and showing an appreciation by the design team of the complications that war would bring, the F.9/37 was designed to be built in small sub-assemblies that could be constructed in small workshops with more basic tools and jigs. This would allow the aircraft to be built across a dispersed network of factories and workshops by semi-skilled laborers, with only final assembly of the various sections being conducted at the main factory – an important factor when facing the prospect of enemy air raids as war loomed on the horizon.

Armament was also truly massive by the standards of the day – two 20mm cannon and four .303 Browning machine guns. For powerplant the Gloster team also showed a canny attitude and designed the F.9 to trial two different engines; the Bristol Taurus air cooled radial and the Rolls Royce Peregrine liquid-cooled inline.

As a result, two prototypes were built, with the Taurus model becoming available first and taking to the skies on its maiden flight on 3 April 1939.

The engines fitted for these initial flights were Taurus T-S(a)’s which produced 1,050hp.

With them, the F.9/37 was practically a dream. The aircraft was extremely agile, capable of surprising maneuverability for such a comparatively large aircraft, yet gentle on the controls, very nice for landing and with excellent pilot visibility, as well as being easy to get in and out of quickly, a frequently overlooked factor. The only gripe appears to be that stability declined when the cooling gills on the Taurus engines were opened fully when in the climb, but once partially closed the aircraft was very nice to fly once again.

But perhaps most impressive was the speed. The Gloster F.9/37 clocked a top speed of 360 mph (579km/h). That made it, in 1939, the fastest British fighter flying.

Plus, its maximum rate of climb was 2,460 ft/min (750m/min) at a height of 12,000 feet (3,657m). That’s not much less than the contemporary Spitfire’s were capable of.

It certainly put the aircraft of other nations into the shadows, being a far more formidable fighter than the French or German equivalents in terms of its performance and handling. In fact, the Gloster F.9/37 looked to be shaping up to be an excellent aircraft.

But then, as I am sure you’ve already figured out, things went awry.

In July the aircraft was badly damaged in a landing accident and had to be returned to the factory to be repaired and rebuilt. At the same time Gloster was pressing on with completing the second prototype, this one equipped with twin Rolls Royce Peregrine engines, each of which produced 885hp.

This aircraft got into the air in February 1940 and proved…meh. Top speed went down to 330mph (531km/h) and performance went down all across the flight profile.

The Peregrine F.9 wasn’t bad particularly, it just wasn’t really good enough to justify building the type, plus in a few months the RAF was about to start taking delivery of their new twin-engine fighter which also used the Peregrine, the Westland Whirlwind, and the Peregrine-engined F.9 didn’t seem to offer a lot over that.

So, it was left to the Taurus engine version to see if that could impressive enough to get a production order.

And here things went further pear-shaped.

In April 1940 the original prototype returned for trials, but now reengined with Taurus T-S(a)-III’s, which only produced 900hp each. Understandably, performance was reduced from the original fit, with this aircraft listed as achieving a top speed of 332mph (534km/h), though the sweet flying character of the aircraft stayed same.

Again, not too bad, but not enough to justify a production order to make the F.9/37 a front-line aircraft. The problem was that though Gloster may have thought they had hedged their bets by selecting to equip the F.9/37 with different engines, unfortunately the pair they selected both turned into lemons.

The issues that the Peregrine had I cover in my article on the Whirlwind, which I shall link to at the end. But the Taurus was also something of a disaster.

The Bristol Taurus was broadly the equivalent of the American Pratt & Whitney Twin Wasp, being a twin-row, fourteen-cylinder radial that was created largely by taking an existing engine and doubling up the rows.

Unfortunately, it differed from the Twin Wasp in one important way. While the famous Pratt & Whitney engine had some teething issues but fairly quickly developed into an excellent powerplant, development on the Taurus…well, it was a bit of a nightmare. Indeed, about the time the reengined F.9 was restarting its flight trials serious consideration was being given to switching out the engines already being used on British production aircraft for Twin Wasps.

A lot of the Taurus’ problems did eventually get solved, but that took several years and as a result confidence in the engine overall in early 1940 was extremely low. Though I don’t know the reason for the switching out of the more powerful engines for the weaker ones during the rebuilding of the damaged first prototype, I suspect it was because there were very real concerns over the reliability of the original engines.

If problems with its powerplant weren’t bad enough for the F.9/37, another major issue was that by 1940, Gloster Aircraft was busy.

Like, REALLY busy.

Gloster were part of the Hawker group and, as they didn’t have a modern design in production when war broke out, their production facilities quickly got assigned to building Hurricane fighters. And that they did, building a thousand of these aircraft in the first year of the war and going on to produce a total of 2,750 Hurricanes by 1942.

Plus, if that wasn’t enough, about the time the second F.9/37 was undergoing its trials in February 1940 the Gloster design team, most notably lead designer George Carter, were taking on a new project that had the potential to make every conventional aircraft flying obsolete.

The Gloster E.28/39 – Britain’s first jet.

This aircraft is going to be a subject for me to cover in its own right soon, but needless to say the potential of the jet aircraft got pretty much all of Carter’s and his team’s attention.

So, between this, Gloster already working to capacity, a pressing need for single-engine fighters for defensive purposes as the war took a turn for the worse in mid-1940 and problems with the chosen engines, the Gloster F.9/37 just didn’t make the cut. A real shame because, as said, it was apparently an excellent aircraft and had solid potential.

Certainly, there was enough appreciation of its potential that it didn’t die off immediately. Gloster proposed modified variants for a new issued requirement in 1940 for night interceptors which, somewhat ironically, would have required the restoration of a gun turret and been fitted with Merlin engines.

That was followed by a final proposal for an even more heavily armed two-seat interceptor/intruder, unofficially dubbed the Reaper, and one of the prototypes was tested through until mid-1941 in various configurations to test this concept. Indeed, according to some sources the trials of the Reaper against Bristol Beaufighter and De Havilland Mosquito prototypes being tested for the same role led to it being judged superior to these other aircraft.

But again, it wasn’t enough to justify the effort of producing the new aircraft, especially as both the Beaufighter and the Mosquito were perfectly adequate for the job and, as said, Gloster had enough on their plate already.

So, in May 1941 the whole project was scrapped and that spelt the end for the Gloster F.9/37; another aircraft cursed with bad engines and bad timing.

Sources/Related:

GLOSTER AIRCRAFT SINCE 1917 by Derek N. James

https://hushkit.net/2021/09/25/why-the-british-cancelled-this-heavyweight-superfighter-in-world-war-ii/

https://www.baesystems.com/en-uk/heritage/gloster-f9-37

https://en.wikipedia.org/wiki/Gloster_F.9/37

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