Impact of fully adopted and reliable 20mm in BoB

[Shortround6]

The Junkers Diesels seemed to do pretty well if the flights didn't require much throttle jocking.
Commercial flights or long range patrols. Problems came in with combat and/or formation flying with lots of variations in power/rpm.

Perhaps this could have been sorted out.

However the next problem is that the Diesels were a bit heavy for the power they provided.
on long range flights the extra weight of the engines was balanced by the lower weight of the fuel used.

However for bombing England in the BoB the Jumo 207 Diesel went about 1430lbs for 1000hp at take-off. The Jumo 211-Da went about 1290lbs for 1200hp at take-off.
The Bramo 323 radial went about 1200lbs (and had no liquid cooling system) and gave 1000hp for take-off.

The Jumo 207 is the one with with a turbo charger feeding the normal supercharger. The single stage Jumo diesels were a bit lighter but none went over 900hp at take-off.
Prototype JU 86R with the 207s first flew in Jan 1940 which is a bit late to to equip a number of bomber groups with planes powered by Jumo 207s by late summer.

 

[PAT303]

My issue would be that having a 20mm cannon is fine. But it backfires when it has to be designed into an aircraft.

Not just the guns but ammunition, it was just as unreliable.

 

[stona]

So called 'spread harmonisation' was still in use for cannon armament, when there were enough of them. When No.150 Wing began its operations against the V-1s one of the first things that Beamont ordered was that the four cannon be 'point harmonised'. Even in 1944 this caused considerable friction with 11 Group* because it was not authorised. Beamont had the clout to get away with it, and it was adopted across his Wing, but a lesser officer would not have been permitted to do it.

* The Tempests were retained in 11 Group because the British had advance notice of the coming flying bomb attacks. They did not transfer to control of the 2nd TAF until later, though Beamont was told that if the flying bomb attacks did not materialise he would be able to provide air support over the invasion area. Beamont did fly over the Allied beach head with 10 Tempests on D-Day itself, but when the V-1s eventually materialised in mid-June, the Tempests were reserved for operations against them.

 

[fastmongrel]

A production run of 297 is not a few dozen but a few hundred. Pre war problems with diesel engines is not the same as having permanent problems with diesel engines.

297 over four years doesn't mean that all 297 were active at the same time. There would have been a few dozen in service at any one point.

Still the Jumo diesel engine aircraft were no harder to destroy than an avgas burner and they always had a habit of catching fire.

 

[The Basket]

What armament was the Spitfire designed for and where?

From my reading the original Spitfire was supposed to have that evaporation cooling that made the He 100 a success.

So if the leading edge is full of tubes then where the guns supposed to go?

 

[Glider]

I read somewhere that the original proposal / mock up had four x 303 but was obviously built with the 8 and the rest is hitory

 

[The Basket]

I think the trousered Spitfire had 4 guns. It looks like the Spitfire we know was 8 guns from the get go.

 

[stona]

The Spitfire 'mock up' was built to F.7/30 and had four guns in the wings.
On 26 April 1935 Mitchell received a newer specification, F.10/35, which called for six or eight guns in the wings. Mitchell told Sorley that he could up the guns to eight with no trouble or delay, but would welcome any 'deletions'. The agreed deletions were a reduction in fuel capacity and the requirement to carry bombs (4 x 20lb).
The Spitfire got eight guns and the rest is history.

The Hurricane gun battery was increased to eight at the same time.

 

[pbehn]

What armament was the Spitfire designed for and where?

From my reading the original Spitfire was supposed to have that evaporation cooling that made the He 100 a success.

So if the leading edge is full of tubes then where the guns supposed to go?

I always assumed (you know what that did) that the original 4 gun Spitfire armament were the two in each wing close together and the extra 4 were the others. Those two pairs of guns are much further out from the prop arc than they need to be which I always thought was to give a bigger evaporative cooling "radiator" in the inboard leading edge. Since evaporative cooling was abandoned and the armament increased before the plane really came off the drawing board

 

[Shortround6]

I guess it depends on what is meant by the original Spitfire as the 224 was so different from the 300.

the guns were in the fuselage (the long troughs under the exhausts) and in the wing roots.
The model 300's wing was 9 feet shorter.

Part of reason for the layout of the Spitfires guns may have been the thickness of the wing. In the Spitfire no belt of ammunition passes over another gun to get to the gun it feeds. the ammo boxes are in between the widely spaced guns and of the closely mounted pair the inboard gun is feed from the inboard side and the outer gun is feed from the outboard side. The outermost gun (no 4) has it's ammo box feeding from the inboard side and is behind the other ammo box.

 

[The Basket]

The Stuka Spitfire ain't no looker.

Fell out the ugly tree and hit every branch on the way down.

Funny always someone saying RAF could have fought the BoB with jets and 20mm cannon but the scary thing is that we could have fought with this abomination.

 

[The Basket]

We know in hindsight that we need Spitfires and Hurricanes and radar and all that in June 1940.

Considering other aspects of the British military in 1940, Fighter Command is on it. Totally modern.

Dowding did like a seance and I just get the feeling that it's amazing how this worked out. As if he knew the future.

If you look at other air forces in 1940 then look at Fighter Command and it's night and day.

Even other RAF commands.

I know very well the weaknesses of the British and the British military and British industry. But Fighter Command in 1940 was a monster. Any harsh criticism is to me unjustified considering what was overall achieved.

Staggering achievement.

 

[stona]

I always assumed (you know what that did) that the original 4 gun Spitfire armament were the two in each wing close together and the extra 4 were the others. Those two pairs of guns are much further out from the prop arc than they need to be which I always thought was to give a bigger evaporative cooling "radiator" in the inboard leading edge. Since evaporative cooling was abandoned and the armament increased before the plane really came off the drawing board

The area of the leading edge originally intended for evaporative cooling extended from close to the fuselage to roughly the outboard edge of the wheel well in each wing. The two guns were then mounted in a position similar to the two inboard guns in the eventual four gun wing. The third gun in each wing was squeezed in as close to the other two as possible (the second and third guns have the least separation), it's only really the fourth gun which had to be fitted a long way outboard.

A radiator for the engine came with the proposed change to the Merlin engine. The first 'PV 12' passed its type test in July 1934, and given Rolls-Royce's close relationship with Supermarine, they would have been among the first to know. The new engine was named 'Merlin' on 10th January 1935 and the first Supermarine drawing to feature a radiator is from 14 January. At this stage it was an auxiliary radiator, the evaporative cooling was retained. This radiator was drawn under the centre of the fuselage, but RJ Fenner always maintained that it was to go under the port wing 'half buried in the wing'. It is a matter of record that eventually the radiator ended up in the starboard wing.

It wasn't until September 1935 that a meeting was held with F.W Meredith and various Supermarine engineers to discuss the fitting and placement of radiator(s) to exploit the Meredith effect, first published in an RAE report by Meredith in June the previous year. It was following this meeting that evaporative cooling was finally abandoned and the 'Meredith radiator scheme' adopted. There is a well known photograph of the prototype, taken head on, in which the original position of the evaporative cooling system is evident, it certainly made it off the drawing board!

The position of the oil coolers was still under discussion in December 1935, just three months before the prototype's first flight.

The prototype was planned to fly in December 1934 and it is likely that a large part of the three month delay was due to the alterations to the cooling system and the development at Farnborough and by Supermarine of Meredith's radiator system.

 

[PAT303]

We know in hindsight that we need Spitfires and Hurricanes and radar and all that in June 1940.

Considering other aspects of the British military in 1940, Fighter Command is on it. Totally modern.

Dowding did like a seance and I just get the feeling that it's amazing how this worked out. As if he knew the future.

If you look at other air forces in 1940 then look at Fighter Command and it's night and day.

Even other RAF commands.

I know very well the weaknesses of the British and the British military and British industry. But Fighter Command in 1940 was a monster. Any harsh criticism is to me unjustified considering what was overall achieved.

Staggering achievement.

Great post.

 

[The Basket]

How much of the Type 224 carried into the Type 300?

Odd to think if the Type 224 Stuka had been successful then the Spitfire wouldn't have existed.

So many butterflies flying about.

 

[PAT303]

What armament was the Spitfire designed for and where?

In 1934 Operational Requirements branch wanted a minimum of 6 guns but preferred 8 to allow for the higher speeds of aircraft, the original requirement was for 4 MG's, 2 in each wing.

 

[stona]

In 1934 Operational Requirements branch wanted a minimum of 6 guns but preferred 8 to allow for the higher speeds of aircraft, the original requirement was for 4 MG's, 2 in each wing.

The Type 300/Spitfire as it stood in early 1935 was built to F.37/34, a 1934 specification that required four guns. It was only when it was decided to bring it into line with the newer F.10/35 specification that this was increased to eight. F10./35 specified either six or eight guns.

 

[stona]

How much of the Type 224 carried into the Type 300?

Odd to think if the Type 224 Stuka had been successful then the Spitfire wouldn't have existed.

So many butterflies flying about.

The Type 224 was built to specification F.7/30 (to which the Type 300/Spitfire ultimately traces its heritage).

It was an experimental aircraft and changed form many times during its life. Many of the features that would later be seen on the Type 300 were first seen on the Type 224, perhaps the most obvious is the large fillet at the wing fuselage join, but the two had nothing physically in common.

The Type 224 prototype aircraft, K2890, was finally taken on charge at Farnborough in July 1935. It's performance was judged '...not such to be of interest in the face of up to date performances'. In May 1937 it went to Martlesham Heath, where it was not flown. Later that year it went to Orfordness where it was used as a gunnery target.

 

[The Basket]

Why was the Spitfire needed to carry 4x20lb bombs? Sink Graf Spee?

If that was official then I can guarantee I don't know the point of that.

 

[Shortround6]

Legacy requirement.
Practically every British fighter from the middle of WWI on could carry four 20lb bombs.
Why it never increased as engines went from 130-150hp to 4-600hp and then to 1000hp is a mystery known only to the members of the air ministry