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

[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.

[bongodriver]

Yeah it seems pretty evident this Crumpp chap is not familiar with the concept of 'can do', its more like 'could do subject to subclause B paragraph 8 having gone through all the correct channels to get a facilitation to arrange several meetings, the minutes of which will be copied in triplicate and sent for further approval'.

[NZtyphoon]

What Crumpp is conveniently ignoring is that Rolls-Royce were already
A) Testing a Merlin at 18 lbs boost and generating 1,536 hp on a special blend of gasoline, benzol, methanol tetraethyl lead in August 1937. (Price Spitfire Story 2010 p. 107) But then Price, like most aviation historians, is an ignorant -non engineering- dweeb who knows nothing about aircraft.

B) testing Merlins IIs on 100 Octane in 1938.

Whatever Crumpp might think Rolls-Royce had been working on modifying Merlins to run on 100 Octane and high boost well before 1940, and with their engineering capabilities would have known what sort of modifications would be needed to get the Merlin II & III series running reliably at higher ratings - the modified cylinder heads would have been developed and ready to use as soon as the go ahead was given in November 1939 to allow Merlins to run at +12 lbs.

If Crumpp had been in charge at R-R at the time nothing would have been done because Crumpp would want every single tiny detail thrashed out at length, and he would know better than everyone else that at least 30 months would be needed for intensive operational testing and development before production engines could be cleared to use 100 octane fuel.

[ATAG_Snapper]

Originally Posted by bongodriver

Yeah it seems pretty evident this Crumpp chap is not familiar with the concept of 'can do', its more like 'could do subject to subclause B paragraph 8 having gone through all the correct channels to get a facilitation to arrange several meetings, the minutes of which will be copied in triplicate and sent for further approval'.

In place of email distribution: "Alright chaps, shut your cake holes and gather 'round....."

The paperwork would follow later.

[Osprey]

In short, we'd have lost the war if Crump had been in charge.

Imagine D-Day on Omaha beach, Crump leading the first wave in Dog Green sector with a clipboard in his hand pointing out all the hazards to the commanders before ordering a full retreat because of failures in Health and Safety policy.