Spitfire production: Griffon versus Merlin

[alejandro_]

I was reading about Griffon Spitfires (Mk XII/XIV) and I wonder why production was rather slow when compared to Merlin variants. Most mass produced variants were Merlin (Mk I, II, V, IX). This can be understood because they were produced over a longer time span. However, production of Mk XII was just over a 100 as it was an interim variant. Spitfire Mk XIV production was ~957, which I don't find very high. First samples were received in early 1944. I have come with a few reasons which could justify this:

- Bomber production taking priority in RAF strategy during 1944-45.
- Spitfire Mk IX being considered as more than enough for practical purposes (Merlin 61/66, two stage superchargers...).
- No major emergencies as in 1944/45 the USAAF was fighting along RAF.
- Griffon production being more complex, changes in Spitfire production hard to implement.

 

[davebender]

I suspect this is the real reason. Under wartime conditions Britain could mass produce a lot more RR Merlins than Griffon engines.

 

[Jabberwocky]

I was reading about Griffon Spitfires (Mk XII/XIV) and I wonder why production was rather slow when compared to Merlin variants. Most mass produced variants were Merlin (Mk I, II, V, IX). This can be understood because they were produced over a longer time span. However, production of Mk XII was just over a 100 as it was an interim variant. Spitfire Mk XIV production was ~957, which I don't find very high. First samples were received in early 1944. I have come with a few reasons which could justify this:

- Bomber production taking priority in RAF strategy during 1944-45.
- Spitfire Mk IX being considered as more than enough for practical purposes (Merlin 61/66, two stage superchargers...).
- No major emergencies as in 1944/45 the USAAF was fighting along RAF.
- Griffon production being more complex, changes in Spitfire production hard to implement.

Add the PR Mk XIX, with another 225 built (most during the war) to the Griffon engine Spitfires as well.

To me, the comparative scarcity of Griffon engine Spitfires is a combination of:

Development problems with the Griffon in 1941/1942 slowing production;
Beaverbrook's temporary order to halt Griffon-engine Spitfire development in mid-1940;
Significant installed fighter base of Mk VII/VIII/IX, Typhoon and Mustang in RAF inventory in 1943/1944;
Large economies of scale already in place with Mk IX/VIII production;
Considerable power gains made by the Merlin (increasing power from 990 hp to 2,000 hp over a six year period). In 1940, Merlin power output eclipsed that of the Griffon.
Not-invented-here syndrome. The Griffon was developed as a Fleet Air Arm engine, and wasn't formally considered for the Spitfire until very late 1939. Most early Griffon engines went to Fireflies, instead of Spitfires.

 

[Juha]

And many Griffons were used to power FAA's Firefly 2-seat fighter.

Juha

 

[alejandro_]

What about priority for Bomber Command in aircraft production? during 1940-43 bombing was the only way of directly attacking Germany, and some believed they could win the war, hence there was a huge investment in this branch of the Royal Air Force.

 

[davebender]

RAF Bomber Command was so huge that it effected a lot more then just Spitfire production. It impacted the entire U.K. war effort.

 

[alejandro_]

RAF Bomber Command was so huge that it effected a lot more then just Spitfire production. It impacted the entire U.K. war effort.

Max Hastings does give data on Bomber Command overall impact on war effort , and IIRC states that it consummed 13%?. Amongst some of the poblems was the reliance on American aircraft for civil transport, which was a disadvantage when the war ended.

Other writers state the effort was 7-9%, but is there more specific data on allocations to Fighter and Bomber Command?

 

[Nikademus]

RAF Bomber Command was so huge that it effected a lot more then just Spitfire production. It impacted the entire U.K. war effort.

Fighter Command also expanded greatly in the midwar years allowing the Rhubarb and Circus actions over France while also keeping a wary eye out for a resurgent Luftwaffe attack on Britian. The 2nd tactical AF org later became a large and prominent force. Coastal Command also expanded as well as it's importance grew. I agree that it sounds more like a technical bottleneck.