An example of a less than fully successful concept, the Defiant was one of the first generation of fighters that Great Britain had on entering World War II.

Let’s look an interesting idea that never fulfilled its promise.

Readers of this site may recall several years back I tagged this as one of the “worst aircraft of World War II”. Although I won’t back track on that, it is worth exploring the idea behind it and why it ultimately failed.
In World War I several two seat fighters, with separate pilot and gunner, saw some success. This was usually in the role of bomber destroyer and balloon buster. The two seater had some advantages with a pilot wholly dedicated to flying the plane, and gunner completely focused on his own specialty. Makes some sense. Even in World War I it was apparent the two seater didn’t generally fair as well against single seat fighters.
But for big targets in the rear areas (London!) a two seater never had to fear encountering a single seater.

In the early 1930s the Boulton Paul Aircraft company came up with a pretty efficient powered turret design for use as a defensive position on bombers. This proved to be more effective than free mounted guns, especially as aircraft speeds and the resulting effects of wind on handling a gun were becoming a bigger issue. As a bonus, the power turret could allow a gunner to control more guns. Add in optical gun sites of the late 1930s and the RAF felt the power turret could effectively fire at twice the range of a free mount.
So it seemed an appealing idea to build a defensive fighter, a bomber destroyer, that could protect English cities. A formation of bombers could be met by a formation of fighters that would slide in alongside and trade fire for a sustained period. Like ships-of-the-line dueling it out.

So an order went out in 1935 for such an aircraft. The two most prominent interested parties were Hawker and Boulton Paul. Pretty soon it became obvious Hawker was heavily committed to their more conventional Hurricane and Boulton Paul, already the main turret provider, became the only contender for a turret fighter/bomber destroyer.

The type first flew in July 1939 and entered squadron service from October of that year. So this was very much an early War type and its operational abilities had to be sorted out quickly. That first Defiant Squadron, No. 264, worked with bomber squadrons flying Blenheims and Hamptons as they developed tactics. Plus some flying against Spitfires to assess its abilities against a fighter. As Spitfire pilot Robert Stanford Tuck affirmed, the type was best as a bomber destroyer and was found wanting as a pure fighter.
The four gun turret (4 x .303 cal) had about the same ammunition supply as the Spitfire or Hurricane, but with half the number of guns it could fire twice as long. The Defiant could also come in below a bomber formation and not be easily seen by the flight crew. Its best option if encountering enemy fighters was to adopt a Lufbery Circle, where the squadron aircraft could all cover each other’s tails.

Unfortunately in the chaos of war its missions were not so tidy and predictable. The Defiant was initially used to provide fighter cover for shipping in the English Channel and North Sea where had some success against bombers. But the first time Bf 109s were encountered 5 of 6 Defiants were shot down. This would continue to be the theme. There were a few cases where enemy fighter pilots were apparently unfamiliar with the type and came in for a tail attack; those didn’t end well for the attacker. But that was always the exception, most often Defiant squadrons were shredded by opposing fighters.

A Second Defiant squadron, No.141 Sqn was added during the Battle of Britain. They failed to heed No 264 Sqn’s “lessons learned” and were handled very roughly by the Luftwaffe. And I believe that was the end of the Defiant as a day fighter. Up to 11 squadrons used the type as a night fighter during the Blitz, some even getting an early airborne radar system. And there was a Defiant Mk II with a Merlin XX engine. Defiant night fighters relied heavily on the “attack from below” tactic that served them fairly well, but night time intercepts did not really become regularly effective until Beaufighters, with better radar and much heavier firepower, entered service the following year.

What went wrong with the turret fighter? There were two big problems right with the initial concept. First, the pilot had no forward firing guns and the gunner often could not intuit what the pilot was doing. So the division of labor was somewhat counter-productive.
Second, an aircraft with the same engine as the early Hurricane and Spitfire was slightly bigger than the Hurricane, with an extra 800lbs of weight behind the pilot. Its flying and handling qualities were fine, but pleasant flying and not enough power are not good qualities for a fighter.
Operationally it was difficult to find a use for the aircraft from the start. Apart from maybe a permanent rear guard it didn’t mix well in contested airspace. Then France fell. That’s something planners had really never even considered. That meant those German bomber streams coming over London would be escorted by single engine fighters. And there was simply no place for the Defiant to execute its planned mission.

This model represents one of No. 264 Squadron’s fighters in those initial battles of July 1940. It is the Airfix kit. Really a fun build. The turret itself was the main source of complexity and was like a whole model in itself. Following the directions I had a brief crisis of confidence, I simply did not believe the turret would ever fit in the tiny opening for it! And indeed significant pressure was required. But surprisingly, it ended with a satisfying click and everything ended in place with nothing broken. I wish I could say that more often!