Inaccurate performance data for BOB fighters in COD comparing to RL data

[Flanker35M]

S!

Crumpp, still some 17 years left of service, going for the full service time Anyways, when looking at that Spitfire Mk.II manual June 1940, paragraph 55 (stating it should be carefully noted) clearly says +12lbs up to 1000ft for take-off or maximum 3min. Rest seems to be +9lbs (all-out for 5min) with no alt restrictions. And continuous/max cruise is +7lbs. So that pretty much says it all IMHO.

Cleared for +12lbs but not for 5min or at any altitude. As that note says 5min is for +9lbs. Out of curiosity how different is the Merlin III used in Spitfire Mk.I being able to use+12lbs for 5min than Merlin XII on Spitfire Mk.II only cleared for take-off up to 1000ft / 3min? Devil is in the details it seems..

[Ernst]

This topic becomes endless. The posters are repeating the same things ad infinitum, name calling etc. No more info can be found here.

The moderatores should lock this topic. All the info is already here. Let the readers decide for themselves.

[41Sqn_Banks]

Originally Posted by Flanker35M

Out of curiosity how different is the Merlin III used in Spitfire Mk.I being able to use+12lbs for 5min than Merlin XII on Spitfire Mk.II only cleared for take-off up to 1000ft / 3min? Devil is in the details it seems..

I thing this is a good start: http://www.jshawmsc.f2s.com/merlin.htm

Not much different from late production Merlin III.

Note that the Merlin XX, which is also very similar to the XII (except of course supercharger, which is single gear in XII and two gear in XX) was cleared for +12 emergency boost (5 min, not altitude restriction) was cleared in November 1940.

[Robo.]

Originally Posted by Flanker35M

S!

Crumpp, still some 17 years left of service, going for the full service time Anyways, when looking at that Spitfire Mk.II manual June 1940, paragraph 55 (stating it should be carefully noted) clearly says +12lbs up to 1000ft for take-off or maximum 3min. Rest seems to be +9lbs (all-out for 5min) with no alt restrictions. And continuous/max cruise is +7lbs. So that pretty much says it all IMHO.

Cleared for +12lbs but not for 5min or at any altitude. As that note says 5min is for +9lbs. Out of curiosity how different is the Merlin III used in Spitfire Mk.I being able to use+12lbs for 5min than Merlin XII on Spitfire Mk.II only cleared for take-off up to 1000ft / 3min? Devil is in the details it seems..

Flanker - as discussed previously in great detail - this does not account for BCC-O, feel free to read posts by Banks (and others) to see how it worked and how it has been used. This is in fact explained in the same manual you mention. It seems we're turning in circles for 135 pages

Good luck in your service, S!

[41Sqn_Banks]

Originally Posted by Robo.

Flanker - as discussed previously in great detail - this does not account for BCC-O, feel free to read posts by Banks (and others) to see how it worked and how it has been used. This is in fact explained in the same manual you mention. It seems we're turning in circles for 135 pages

Good luck in your service, S!

However contrary to the Spitfire I manual the Spitfire II manual does not state that the boost control cut-out will provide +12 boost and that it is authorized for short time and emergency.

That the cut-out will provide +12 boost is obvious, it has the same boost control as the Merlin III and it is also proven by the later amendments.
The question that remains is when it was authorized.

[Flanker35M]

S!

Will check the link, thanks Banks Been more into the DB6XX-series engines as they really were ahead of their time with fuel injection and many automated things. But never hurts to learn about RR engines either

[winny]

Just found another contemporary source.
Flight Magazine - April 1940

[NZtyphoon]

An interesting clip on building the Merlin:

Building the Merlin

Wish the original soundtrack had been kept instead of adding the usual muzak

[winny]

I'd just like to add a little example of how procedures differed during the war when compared to peacetime/modern times.

Spitfires suffered from a couple of problems that would today result in the grounding of the fleet. Namely the "Skew Gear problem" in Merlins where the skew gear would fail randomly and catastrophically, (this happened to Alex Henshaw a number of times) and the Piston seizures on Packard Merlins - caused by the fact that the piston heads were not machined, to save time, and were left to wear to shape, or in some cases seize as the push rods got bent. Neither of these problems would be acceptable today. They simply could not afford to halt production to find the source of the skew gear problem, so they continued making the engines as was, up until the point that they fixed it. This almost certainly cost lives and certainly cost aircraft.