IX Spitfire 20mm Cannon blisters

that looks interesting. I think the best source for you would be the Squadron Spitfire walkaround. And while at when you get to the cockpit this site might be useful as a reference http://spitfiresite.com/2010/07/anatomy-of-spitfire-cockpit.html .

Cool link. Haha that Spit was built in my home country

Yeah I need some shots of the upper wing surfaces of a mark 9. Either  way the only ones Ive seen are the slimmer tear drop type.

Argh, cheers Mike. Thats a great site for info bro. Ta.

Sorted I guess (??)

http://spitfiresite.com/2010/04/concise-guide-to-spitfire-wing-types.html/2

In field conditions, it was often sufficient with two cannon armament and many of the four-cannon Spitfires were converted to fly with either outboard or inboard pair of Hispanos, or else converted to B-standard armament. Later on, production aircraft carried the two 20mm Hispanos and four Brownings. In such circumstances, the very large blister on top of the wing was not required and a new, more streamlined cannon breech cover was provided, with narrow blister fairing over the inboard cannon position and flat surface over the second, unused cannon bay.

In that link you provided, select the entry on cannon blisters (if you haven't done so already).  Basically the large covers were only found on some early production Mk. IX's but since duel cannons on each wing were never operationally used on this type, plus the fact it created drag, a more narrow blister was made.  Too bad no date is given to when this change over was done - perhaps an indication it was switched quite early in this mark's career?

regards

Jack

It is not a good idea to infer things from museum examples as they are often late-build with a post-war history.

When the ‘C’ wing was first introduced the installation of four 20 mm cannon was one of the options available, and it was not unusual to see them on Mk Vs. Therefore the standard ‘C’ wing style cannon bay covers featured wide fairings, each designed to house two cannon ammunition feed drums.

On the new Mk IX, the four-cannon option hade to be abandoned for reasons of flight safety. The Certificate of Design for the Type 361 stated: To offset the increased weight of the power plant the armament is limited to (a) 2 cannon and 4 Browning guns (b) 8 Browning guns. Therefore, as far as can be ascertained no production Mk IXs flew with four cannon (nor, for that matter with eight Brownings). However, for quite a while they were fitted with the standard ‘C’ wing cannon bay covers with wide blisters.

A new cannon bay cover was duly developed, with a single narrow blister over the inboard ammunition feed drum. The new covers were probably not fitted to production aircraft until those delivered in late January/February 1943. Photographs from early April 1943 prove that EN459 featured broad blisters on operational service, while EN464 of the same batch, photographed fresh from the factory at the beginning of February 1943, was already fitted with narrow ones. The CBAF started turning out Mk IXs at just about the same time. Photographs show the earliest F.IXs originating from that plant, built as Mk Vcs and converted at Rolls Royce Hucknall, featured the double-blister covers. The narrow-blister covers had been introduced at CBAF by May 1943, probably before the MA serial range. MK V Tropicals made in the same batch during May featured the new single-blister covers.

As EN315/ZX*6 precedes its sister EN459/ZX*1 in production it would certainly have had the wide blisters as did EN459. Likewise, EN398/JE*J was also fitted with wide cannon blisters. This is confirmed in a photograph taken of it before it was adopted by Johnson when it was code AE*B.     

Thanks for the info.

Glad Im not going with the standard box build serial then of Johnsons aircraft.. Ive opted for the Canadian ace  Buzz Beurlings Spit, his mark 9 back in Europe didnt wear the rare wide blisters. ( Serial decals of Buzz from the after market Barracuda store) Cheers again.