Bug 174 on 12lbs boost. Review please.

[Kwiatek]

Originally Posted by DD_crash

This might be a dumb question but has anyone asked the question of 100 octane availabiliy during BoB at the Imperial War Museum at Duxford?

But what for??

There is no question that 100 Octan fuel was used during BOB.

[DD_crash]

Not according to Herr Kurfaust. And the "discussion" is about how common it was. If "a lot" or "most" squadrons used it then surely it should be in the game?

[Kwiatek]

Really dont care Herr Kurfurst. He is known 109 fanboy and it is really hard to call him objective in such case regarding 109 vs Spit performance.

Im sure 100 Octan performance for british fighters should be implement in game.

[Kurfürst]

I wonder why I voted for the inclusion of 100 octane in the bugreport forum. Oh, yes, I forget, I am a mindless fanboy.

[NZtyphoon]

Originally Posted by Kurfürst

I wonder why I voted for the inclusion of 100 octane in the bugreport forum. Oh, yes, I forget, I am a mindless fanboy.

Mind you he's still spamming the bug report with rubbish so it's quite clear that Barbi has a fixed agenda and is trying to ensure that the message about 100 octane and +12lbs boost is scrambled and confused for the developers. He's still trying to present the spurious "Pips papers', which he has never seen, as "evidence" that the RAF only allocated the fuel to a select few frontline fighter squadrons. Pathetic and laughable.

[Kurfürst]

I post the evidence I have on a thread which is about collecting all the evidence to be reported to the developers.

NZTypoon and Osprey wanted to keep that evidence away from the developers, now asking the evidence to be removed and present only filtered evidence.

A verdict on this is easy to make.

[41Sqn_Banks]

Originally Posted by Kurfürst

I post the evidence I have on a thread which is about collecting all the evidence to be reported to the developers.

NZTypoon and Osprey wanted to keep that evidence away from the developers, now asking the evidence to be removed and present only filtered evidence.

A verdict on this is easy to make.

IMHO most of your comments are very valid and add some evidence that were not presented in the bug report so far. I don't understand why they should be removed, especially as they support the request for +12 boost.

- They clearly show how the amount of issued 100 octane increases during and eventually overtakes the issued of 87 octane.
- They show that selected stations (Bomber Command stations with Blenheim and Fighter Command stations with Hurricane and Spitfire) received 100 octane in May 1940.

Regarding the opinion of Pips I'm sure we all will be glad to consider the the "Pips papers" as a valuable evidence as soon as they are found and properly sourced.

[NZtyphoon]

Originally Posted by 41Sqn_Banks

IMHO most of your comments are very valid and add some evidence that were not presented in the bug report so far. I don't understand why they should be removed, especially as they support the request for +12 boost.

- They clearly show how the amount of issued 100 octane increases during and eventually overtakes the issued of 87 octane.
- They show that selected stations (Bomber Command stations with Blenheim and Fighter Command stations with Hurricane and Spitfire) received 100 octane in May 1940.

Regarding the opinion of Pips I'm sure we all will be glad to consider the the "Pips papers" as a valuable evidence as soon as they are found and properly sourced.

I know 'Pips', who is a member of this forum, absolutely rushed to validate the existence and authenticity of the papers he claimed to have discovered when asked, very politely, by others to participate in the thread pertaining to 100 octane fuel...but then again a second hand summary of papers Barbi has never seen on a seven year old thread which is closed to non-members of that particular forum is more than enough evidence to prove anything.

[Kurfürst]

Originally Posted by 41Sqn_Banks

Regarding the opinion of Pips I'm sure we all will be glad to consider the the "Pips papers" as a valuable evidence as soon as they are found and properly sourced.

IMHO the 'Pips papers' fit in well with the current trail of evidence. After all the May papers as you noted tell of the issue of 100 octane to the selected stations (which is what Pips is saying, though he quantyfies it at 25%).

He notes that the situation eased in August with the arrival of the first Middle East fuel shipsments. This is again reflected in the August 7 memo posted which notes 100 octane is now cleared for all operational aircraft.

The fuel issues again show the issues increased in the automn, especially end of September which is again line with the 'Pips paper' and Pips statements.

I wouldn't be surprised if Pips would have found the same papers, but had an access to a more complete trail of papers, than what is Glider/lane has been willing to disclose to us. Nota bene that Pips shared his findings some 8 years ago, well before Glider had seen these documents himself.

But this has been done to the death. The devs will decide, but indeed the papers I have posted definitely support the need for the addition of RAF 100 octane variants.

[41Sqn_Banks]

@Ospey I'd like to rephrase some sentences in the initial post. The changes sentences are in bold.

Description
Presently if the boost control cut-out is enabled on Spitfires and Hurricanes and full throttle applied there is no increase in boost above 6.25lbs. This results in reduced and inaccurate performance of RAF fighter aircraft.

During the BoB all frontline fighters had been modified to use 100 octane fuel in their Merlin II and III engines which allowed the engine to achieve 12lbs boost under strict limits. The Merlin XII engine fitted to the Spitfire II was designed to use this fuel from the factory. The approval and introduction of these changes gave the RAF fighters a performance boost in top speed, acceleration and rate of climb up to the Full Throttle Height (FTH) of about 18,000ft. At sea level a Spitfire was about 30mph faster when the boost control cut-out was enabled.

Merlin II and III (fitted to Spitfire Ia and Hurricane Ia)
The Merlin engines have a mechanical supercharger and can deliver up 17lbs to 20lbs of boost at S.L. with the throttle valve fully open using either 87 or 100 octane fuel however this would cause serious engine damage by pre-detonation in the cylinders. Because of this the Merlin II and III have a boost controller fitted which limits the boost to only 6.25lbs. A boost control-cut was fitted to disable the boost control and give the pilot direct control over the throttle valve. With modification to use 100 octane fuel the boost control cut-out was modified to limit the boost to +12 even if the boost control was disabled. The pilot subsequently could increase from +6.25lbs boost to +12lbs boost for emergency (= combat) purposes by enabling the boost control cut-out, which was the ‘safe’ power that the engine could produce when 100 octane was used. The use of emergency boost was limited to 5 minutes. The boost control cut-out was wired to indicate to the ground crew that it had been used and to make necessary checks. The Spitfire had a red lever at the front of the throttle control that was flipped and the Hurricane had a valve at the instrument panel which was pulled (“pulling the tit”).

Merlin XII (fitted to Spitfire IIa)
The Merlin XII did not require modification in order to use 100 octane fuel and had two systems to increase the boost above rated boost of +9lbs.

a. Boost control cut-out
The boost control limited the boost to the rated +9 lbs of the Merlin XII. The boost control cut-out was fitted to achieve emergency (= combat) power of +12lbs boost (see pilot notes) for 5 minutes up to full throttle height. The use of emergency boost is reported since 21 August 1940, 8 days after the Spitfire II entered service.

b. Gate control
In addition a gate control was fitted to achieve a special take-off boost. The gate control was enabled by pushing the throttle above the rated position through the gate. The gate control set the throttle valve to a predefined opening to achieve 12-12.5lbs boost. As the opening is not adjusted with the decreasing atmospheric pressure at altitude the boost will fall off very quickly. The take-off boost was limited to 1 minute and 1000ft altitude.