Spitfire MKV and Merlin45 in 1941

[Kwiatek]

H!

I making some realism mod for IL1946 and need info about performance of Spitfire MK V with Merlin 45.

I have problem with Merlin 45 and boost which was used early in 1941.

Most Spitfire MKV RAF test in 1941 was made using only + 9 lbs so performance of these plane was derated.

Spitfire Mk VB W.3134 Report

Some charts show that Spitfire MK V with Merlin 45 could get +12 lbs emergency power or even +16 lbs.

So how its really look? RAF didnt test Spitfre MKV initialy with emergency power? Or +12 lbs ( or +16 lbs) was initialy not allowed Merlin 45?

Any help?

 

[HoHun]

Hi Kwiatek,

>So how its really look? RAF didnt test Spitfre MKV initialy with emergency power? Or +12 lbs ( or +16 lbs) was initialy not allowed Merlin 45?

It's pretty certain that the +16 lbs/sqin rating resulted from technical changes implemented in about August 1942 and communicated to the squadrons by an Air Ministry memorandum, reproduced in Price' "Spitfire - The Complete Fighting History".

It's not entirely certain if the Spitfire V was initally cleared for +12 lbs/sqin, or if it started into service with +9 lbs/sqin only. I tend towards the latter opinion.

I think there was an in-depth discussion of this topic already here on this board, but I can't seem to find it currently

Regards,

Henning (HoHun)

 

[Kwiatek]

Thx HoHun for quick replay. So i think i got still a problem

Difference between 9 lbs ans 12 lbs is very noticable at low to medium alt so it make big difference between Spit MK V and 109 F performance comparison.

Maby there is someone who can resolve it?

 

[HoHun]

Hi Kwiatek,

Here is the old thread: http://www.ww2aircraft.net/forum/engines/merlin-40-series-performance-curves-16568.html

Regards,

Henning (HoHun)

 

[claidemore]

It gets confusing comparing climb, all out level, takeoff and combat power levels. In a later date Merlin 45 the numbers would be 12 lbs takeoff, 9 lbs climb, 16 lbs combat (5 min.)

I always understood the numbers as being 9 lbs for takeoff, with 12 lbs emergency combat power (for 1941),,,,and 12 lbs takeoff, with 16 lbs emergency combat power (for 1942).

They also used different boost levels at different rpms, for example, the Merlin XII used 12 lbs boost at 2270 rpm for takeoff (3 min), but 9 lbs boost at 3000 rpm for max combat (5 min).