Bug 174 on 12lbs boost. Review please.

[Kurfürst]

Originally Posted by Glider

This as you know is rubbish. If you and I were to each submit a research paper on our opposing views I would be able to quote a mass of published works from different historians, participants in the battle, official papers, prime sources of data, publications from engineers, combat reports, station reports and others to support my case.

You would be limited in the extreame. Little more than an over emphasised minute from one meeting, an operating manual for an engine that had been out of production some time before the BOB and not a lot more

You see that's your problem. You desperately try to support a fantasy by spamming a lot of irrevelant papers that do not even support your case, while all I need to is to produce about 5 papers which clearly support my case.

Now I agree that doesn't automatically mean that I am right, but the burden of proof is on you to support your case with facts not theories.

There's no theory here but facts. Fact is that the RAF originally meant to support a limited number of fighter Squadrons, fact is that the only paper available shows they did convert a limited number of fighter Squadrons by May 1940, fact is that full clearance was not given until August and fact is that fuel issues show the majority of the fuel issued during the Battle was 87 octane, fact is that evidence of 100 octane use only exist for about 1/3 of the Fighter stations, and even many of those only towards the end of the Battle.

I have said many times that the case for is a strong one not a perfect one but its a heck of a lot better than he case that you have

Despite that perception of yours most people here handle your theory with a great deal of scepticism.

[Kurfürst]

Originally Posted by Osprey

Kurfurst must be very envious of the massive supporting evidence of 100 octane use by FC. Funny how he doesn't need even a fraction of this level of direct evidence and records to convinced himself that the Germans were using 100 octane though. One photo of a destroyed 109 is enough for him and it unquestionable from then on - Germany must have had it in abundance and were using it from day 1.

Sadly for you the use of 100 octane by the German fighters from the start of the Battle is documented in far greater detail than in the case of RAF Fighter Command. We know the exact dates, the exact units using the fuel, we have detailed records of German High Command meetings detailing these as well as British reports of captured fuel samples, photograph of downed aircraft and so on. We even know the exact amount of aircraft using the fuel at some date.

The envy and denial is all yours.

[robtek]

Originally Posted by Osprey

.....One photo of a destroyed 109 is enough for him and it unquestionable from then on - Germany must have had it in abundance and were using it from day 1.

What a fanboy.......

With such ridiculing, wrong statements you don't improve your image!!

He has never said or written what you have posted.

That 109 is proof that c3 fuel was used in frontline squadrons, as the number of mounted DB601N engines on Bf109 and Bf110 is evidence for it.

Though only a lesser part of all fighters used it.

I say it again, it is proofed that many british fighters used 100 octane, there is only evidence that ALL did use it.

There possibly will never be a PROOF that 100% of all fighters of the FC used 100 octane during the BoB, so this discussion is becoming more and more futile.

For CoD the implementation of duplicate models with slightly different FM shouldn't be that hard, i assume, so that the mission builders and server operators can create their version of the BoB / BoF / CB.

[GraveyardJimmy]

Originally Posted by robtek

There possibly will never be a PROOF that 100% of all fighters of the FC used 100 octane during the BoB, so this discussion is becoming more and more futile.

But only because no matter how often evidence is produced there will always be someone who says "ah! But you don't have a document showing that the out of commission aircraft that was being scrapped for parts wasn't leaking 87 octane rather than 100!"

[bongodriver]

When evidence becomes practically overwhealming it is as good as proof, the real futility is the resistance being put up against 100 octane fuel, this thread is 'not' about the LW use of 100 octane it is about the fact that right now the fuel modelled for the RAF is incorrect and more to the point the performance even for that fuel is incorrect, it really does seem there is only scope for single fuel types in game therefore the most prevalent ones should be modelled, in the case of the LW that is 'not' 100 octane and in th case of the RAF it is 100 octane.

[robtek]

But the evidence isn't overwhelming, there is lots of evidence for single flights, but where is i.e. the collection of reports from a single AC from ALL active fighter squadrons on a given day during the BoB, documenting the use of 100 octane on that day, that would be overwhelming evidence.

The evidenc is so far only indicating that there is a strong possibility that ALL used it.

[Kurfürst]

Originally Posted by IvanK

Kurfurst you said:

"The Spit II runs on 100 octane by default, but its emergency limits are lower - 9 lbs vs 12 lbs - and is/was at low altitude. It is a bit better at higher altitudes though."

That is not IMO correct. In the case of the SpitII +9lbs basically became the full throttle setting (i.e. the equiv of 6.25Lbs in the MKI) 12Lbs was still available in two ways by way of the throttle gate for take off operations and by Boost Cut out for combat use.

This is a correct description IMHO for 1941. It is not a correct description for 1940.

It depends on what timeframe you are looking at.

The BoB era summer 1940 (unamended) manual of the Spitfire II clearly notes the limits being:

+12 lbs for take-off up to 1000 feet or 3 minutes.
+9 lbs for combat (5 minute limit)

This +12 lbs could be used near the deck of course, but its near useless since boost will immidiately start to fall with altitude (unlike the Spit / Hurri I's boost cutout, it does not lasts up to FTH).
Boost drop curves of Mk II trials suggest that even with the gate open, the boost will fall back from +12 at SL to normal combat rating of +9 lbs by 4000 feet altitude (ca. 1200 meters), obviously with the same performance.
Thus its somewhat similiar to the 109E/110C 1-minute takeoff boost - its effective up to 1-2000 meters only.



It's only later, amended manuals (presumably from 1941) that are clearing +12 lbs for combat, too.

The RAE standard climb tests are flown at +9Lbs Boost for instance.

RAE tests were flown +9 lbs boost and 2850 rpm, as noted in the Spitfire II manual this was the 30-min rating at the time. It did not give the same power and performance as +9 lbs/3000 rpm, of course.

In short our Spitfire II with its maximum +9 lbs rating and performance is correct and historically accurate for the BoB airframe. +12 lbs rating was not cleared for it for combat use during the BoB period.

Should 1C decide to introduce a post-BoB 1941 variant (doubtful), a +12 lbs version would be feasible, of course.

[bongodriver]

something is not quite right about a 9lbs boost being ok for climb for 30 minutes when climbing is the more stressfull in terms of cooling etc and only having a 5 min limit in level flight with more cooling, I don't see why 9lbs boost and 2,850 rpm couldnt be maintained in level flight for at least 30 mins.

[Kurfürst]

Originally Posted by bongodriver

something is not quite right about a 9lbs boost being ok for climb for 30 minutes when climbing is the more stressfull in terms of cooling etc and only having a 5 min limit in level flight with more cooling, I don't see why 9lbs boost and 2,850 rpm couldnt be maintained in level flight for at least 30 mins.

I don't see a reason either. These names for the ratings are somewhat arbitrary, naturally there's nothing preventing you from using 9lbs boost and 2,850 rpm for level flight, apart from temperatures and increasing engine wear. The names like 'combat' and 'climb' were somewhat arbitrary.

[bongodriver]

apart from temperatures and increasing engine wear

which logic dictates are lesser in terms of level flight.........it has occurred to me that those limitations seem more geared toward RPM as opposed to boost, if 9lbs boost can be used for 30 mins then tchnically it is not limiting, usually a 5 min limit is the true factor, this is still a factorisation that applies today even in jets, TO thrust is a 5 min limit, anything below that is a MCT (max continuous thrust), I susspect the 30 min limit is really a limit in terms of oil cooling for the prop govenor system.