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

[Skoshi Tiger]

Originally Posted by NZtyphoon

http://www.spitfireperformance.com/dowding.pdf

Note he also uses the expression "Pulling the Plug" referring specifically to +12 lbs boost.

Very interesting read, NZ.

I also like point 5 which states "The consequences of exceeding the engine limitations are liable to manifest themselves on some subsequent occasion, perhaps during night flying or over the sea ......"

Regardless of the type of fuel being used (the limits being different in each case) the damage being done is generally not instantainous and will not result in immediate loss of the engine (as I have heard it being argued in some threads), but will be dependant on how far over the limitations and for how long they're exceeded for.

To fully realise the damage being caused to the engines we would need to have resource management implemented in the game where this type of damage is accumilated and passed on to subsequent mission. (with maintenance being able to repair the damage ideally!)

It'd also make for interesting senarios where all the good planes are used up and we are only left with the bunkies! (Janes USNF had a good system like this for campains!)

Cheers!

[Crumpp]

Then explain why Dowding found it necessary on 1 August 1940 to send a memo to All Groups, ALL Fighter Stations and ALL fighter squadrons stating that +12 lbs boost

Well one day, all those units will be equipped with 100 Octane. It is not proof that all of the operational units were using it. Why put the word out on something like the information in that memo piecemeal?

What is proof that that 100% of the operational units were NOT using is the Notes on a Merlin Engine found in the Operating Notes.

That is a fact.

[Crumpp]

the damage being done is generally not instantainous and will not result in immediate loss of the engin

Sometimes it will and sometimes it will not.....

It all depends and it is just as likely to end your trip that flight as the next if the motor is damaged.

[Crumpp]

You now want to claim that when pilots refer to pulling the plug it meant they went to 10.55 lbs boost on 87 octane fuel, right?

I am not claiming anything outside of known facts, NzTyphoon. I will leave the speculation to you.

The known facts are that system was in place before 100 Octane fuel was around as evidenced in the 1937 RAF training manual.

The Operating Notes will specify the authorized fuel for the aircraft. The type Operating Notes clearly state that "ALL Operational Units - 100 Octane" after the fuel is adopted for all operational units.

We don't see that in any of the Operating Notes during the BoB. Only the Spitfire Mk II carried the 100 Octane specification. The rest require replacing the heads and in some cases, rings as well as the required modifications to the fuel metering system. This work was performed at Service Inspection intervals. Do you know what that means?

[NZtyphoon]

Originally Posted by Crumpp

Well one day, all those units will be equipped with 100 Octane. It is not proof that all of the operational units were using it. Why put the word out on something like the information in that memo piecemeal?

That is a fact.

Absolute nonsense! The memo says nothing about "In Future, once 100 Octane fuel becomes available..." it was written in the present tense stating unambiguously that too many pilots were using +12 lbs boost for situations other than emergency.

Originally Posted by Crumpp

Why put the word out on something like the information in that memo piecemeal?

Pure speculation on your part.

[NZtyphoon]

Originally Posted by Crumpp

I will explain this ONE time and then I will probably ignore you as I don't think you have much to add. It is according to the training manual and fits with everything I have already told you about Operating Notes.

Nonsense - it has been explained to you several times that the operating limits posted in the Pilot's Notes were relevant to the fuel the engines were designed for, as explained long ago to you in the Pilot's Notes General 1st ed. Any alterations to those operating limits were issued to the pilots as supplementary slips which were then pasted into the Pilot's Notes. You continue to ignore this because it does not suit your "argument".

[Crumpp]

were relevant to the fuel the engines were designed

Not how it works by convention and Air Ministry law. The operating notes define the current airworthiness limits.

[NZtyphoon]

Originally Posted by Crumpp

Not how it works by convention and Air Ministry law. The operating notes define the current airworthiness limits.

Wrong again: read the Pilot's Notes General (attached)

[Seadog]

Originally Posted by Crumpp

The rest require replacing the heads and in some cases, rings as well as the required modifications to the fuel metering system. This work was performed at Service Inspection intervals. Do you know what that means?

The March 20 1940 memo clearly states that new built aircraft already had the internal engine mods:

http://www.wwiiaircraftperformance.org/ap1590b.jpg

Given the production numbers for Hurricanes/Spitfires and RAF operational and combat losses prior to the start of the BofB, it is extremely doubtful that any unmodded aircraft were still in front line service. Production during March, April, May and June, and July, of 1940 would have amounted to approximately 1500 Hurricane/Spitfire aircraft, or greater then RAF FC's front line strength at the start of the BofB.

The memo clearly establishes that all RAF FC Hurricanes/Spitfires were modded for Hundred octane fuel and 12lb boost prior to the start of the BofB.

[41Sqn_Banks]

Originally Posted by Crumpp

I am not so sure "pulling the plug" has anything to do with 100 Octane use at all.

The 1937 RAF Training Manual has instructions for boost cut out independant of 100 Octane fuel.

Additionally this certificate list the boost pressure well above the rated 6 1/2 lbs without boost cut out. The only approved fuel for this aircraft is 87 Octane.

http://img19.imageshack.us/img19/255...ertificate.jpg

I hope you guys are aware that the line "Emergency 5 mins.max." is related to "95°C" oil inlet temperature?



This test certificate has a better layout: http://www.spitfireperformance.com/k...ertificate.jpg

The power curve is a simplified form of this graph: http://forum.1cpublishing.eu/attachm...1&d=1337143252
and most certainly only contains calculated values which were derived from certain reference values or were applied shorty under controlled conditions to determine the engine power.