SPIT MK I/II and over boost

[VO101_Tom]

Originally Posted by klem

Possibly. I haven't looked into it but perhaps the 'undermodelling' of the Spitfires is because they are modelled with 87 Octane?

Originally Posted by Kurfürst

Frankly I am not sure about them. Do they (Mark Is, they seem to be modelled with 87 octane boost levels) not meet specs for a 87 octane one? Climb too slow? Or..?

No.
Couple of months ago i compared the www.spitperformance.org graphs with the game speeds (here). The graphs show the 6lbs boost (with 87 oct. fuel) speed of Spitfire. The 109 would be faster, but not that much – if we look at the proportions of course, because now the 109 is slower than it should).

[klem]

Originally Posted by VO101_Tom

No.
Couple of months ago i compared the www.spitperformance.org graphs with the game speeds (here). The graphs show the 6lbs boost (with 87 oct. fuel) speed of Spitfire. The 109 would be faster, but not that much – if we look at the proportions of course, because now the 109 is slower than it should).

Thanks tom, it was just a thought.
(I think this is the link you meant http://www.spitfireperformance.com/spitfire-II.html )

================================================== =

@Kurfurst. Sorry if I was not clear. I was talking about the Spitfires that are universally claimed to be "underperforming", these are the Spitfire I and Ia. I did not mean the Spitfire IIs.

I did some quick checks on the Mk II a few months ago against the MkII report linked above. I couldn't get it to fly as fast as the report stated but it was very close, just a couple of % under. Mind you I was pretty crude about it, as it meant thrashing the engine at the maximum boost I could make at that altitude (the report suggests +9lbs boost was used) and eventually it broke. So not to be taken too seriously and probably also impatience on my part. Results:-

Alt Boost RPM ASI mph ASI in report
6500 +5.3 2990 280 between 306 @ 5,000' and 326 @ 10,000
10000 +5.3 2990 280 326
15000 +6.2 2990 270 345
(on another run at 10,000' I seem to have written down +5.3 and 290 mph {?!} )

All below the reported data but of course I could not get +9lbs boost.

You may find this site interesting. I can't vouch for its accuracy butit looks pretty good to me.....
http://www.spitfireperformance.com/
http://www.spitfireperformance.com/spit1vrs109e.html
You can see from the level speed chart why we want the 100 octane - and I can understand why you would not be happy about that. By the way I have read several bio accounts of how, in the BoB, the 109 would escape in a dive but on occasions it was possible for the Spitfire to catch them in long chase.

Incidentally on use of 100 octane fuel, I know we seem to have agreed to disagree but that last link contains the following ...

"As of 31 March 1940 220,000 tons of 100 octane fuel was held in stock. The Co-ordination of Oil Policy Committee noted in the conclusions of their 18 May 1940 meeting with regard to the "Supply of 100 Octane fuel to Blenheim and Fighter Squadrons" that Spitfire and Hurricane units "had now been stocked with the necessary 100 octane fuel". The Committee recorded that actual consumption of 100 octane for the 2nd Quarter 1940 was 18,100 tons.

Jeffrey Quill recalled:

It was only shortly before the Battle of Britain that we changed over to 100 octane. It had the effect of increasing the combat rating of the Merlin from 3000 rpm at 6 1/2 lb boost (Merlin III) or 9 lb boost (Merlin XII) to 3,000 rpm at 12 lb boost. This, of course, had a significant effect upon the rate of climb, particularly as the constant speed propellers (also introduced just before the battle) ensured that 3,000 rpm was obtainable from the ground upwards whereas previously it was restricted by the two-pitch propellers. It also had an effect upon the maximum speed but this was not so significant as the effect upon rate of climb."

What is interesting apart from the date by which FC was converted is that quarterly use was 18,100 tons against a stockpile of 220,000 tons. There was no shortage.

[Osprey]

Klem, he's seen all of that but he just isn't interested. Tom's post is interesting, I will have to read more on the top speeds since I am quite surprised that the 109E-1 is marked @ 302mph vs the Spitfire 283mph. I know it's @SL but that is rather a lot.

I'll answer all in one post if you can stomach it

Originally Posted by csThor

...I think it is a bit far fetched to say that the RAF types are modeled the way they are because of the lobbying of a few loud people. That gives them much more influence than they really have. But ...
It's one thing to vehemently defend the evidence or documents which point to the RAF using 100 octane fuel for its fighter squadrons (which I, as a LW-centered player with an avid interest in military history agree with). But I have also seen several discussions being more or less successfully derailed by the same outspoken RAF fans once the subject of german performance, and especially the question of the DB 601N equipped types, was mentioned. People may have their personal interests, that's fine and normal, but it must absolutely not lead to them wearing blinders and red/blue-tinted glasses which doesn't allow them to be impartial anymore. Being a fan is one thing, being a fanatic is another.

I oppose all types who argue this. I don't get involved in the DB601 argument because I don't know anything about it. Show this evidence and I'm sure you'd get support from the likes of Klem, Al Sch... etc and myself here.

Originally Posted by Kurfürst

Yes the very same I was referring to, although the full story goes that I have referred Glider to the findings of an Australian guy going under the handle Pips who posted the summary of this paper several years ago on butch's board. BTW Neil Stirling was also participating, but he keeps dead silent about this paper on his site propagating 100 octane use.

Now, despite being perfectly aware that he needs to contact this Australian guy, Glider kept b!tching to me about producing the paper, of which I have only seen a summary on a board. I kept telling him to contact Pips and ask him.

Instead, Glider kept asking me, living 10 000 miles from Australia to produce the paper found by an Australian, in Australia.

Then I gave Glider the URL to the discussion where this was posted. At first he claimed "he could not find the alleged discussion", then went back asking me, living 10 000 miles from Australia to produce the paper found by an Australian, in Australia.

After a while Glider gave up this tactic of dismissing the paper, and claimed he contacted the Australian archieves, but the Archive said they've never heard about it, and again went back asking me, living 10 000 miles from Australia to produce the paper found by an Australian, in Australia.



Lastly, Glider reproduced the email reply of the Australian archive staff, who in reality replied to Glider's vaguely worded email (somewhere along the lines 'gimme the paper of 100 octane') that given such inaduquate reference that he gave, its not possible to find it and he should supply accurate and precise reference so they would try to dig it up.

You may have already guess that after that Glider went back asking me, living 10 000 miles from Australi, having seen but a summary of the paper on a discussion board and giving him all details I've known about, a to produce the paper found by an Australian, in Australia.

At that point I believe it's understandable that I came to the conclusion that, for entirely subjective reasons, it may not be possible to have a fruitful and rational discussion on the matter with Glider.

Then you came into the picture and told your (half-)story, and so I've told mine, and now people can make up their minds about you, Glider, and the concept of credibility.

Just to understand you then. You are dismissing a multitude of documents which have been produced in various forms from the time in favour of a single one which you cannot produce on the basis that the person who didn't believe it but tried to get it, couldn't, and neither could you?
Seriously Kurfurst, do you not see the gaping hole in your argument? I'm not kidding when I say this but continuing with logic like this generally ends up with the propagator being called a lunatic. Is it just really because you are unable to accept that you are wrong or is there some other reason? You can't use the same protocol which courts of law use, there is no innocent until proven guilty, it's perfectly acceptable to use circumstancial evidence if there is enough of it.

Originally Posted by Kurfürst

Hmm, Spitfires being undermodelled. Interesting.

Klem, may I ask you to try something.

Pick a Spitfire II.
Bank it 90 degrees.
Pull back the stick fully forward.

Come back here and share your observations about it.

What exactly will this prove? That the Spitfire out-turns the 109? It does.



I'm presently reading "A Willingness to Die" by Brian Kingcome, his memoirs. He was a frontline BoB Spitfire pilot for 92 Squadron @ Hornchurch. Last night I read, on page 123, chapter 5, "The Phoney War and The Real Thing" he writes "slowly we reverted almost to a peacetime routine, time of year and sunset permitting, we usually ended our day with a beer or so in the mess before setting out on a pub crawl, pooling our petrol coupons or occasionally filching the odd gallon of 100 octane aviation fuel from the bowsers at dispersal.". This was during the phoney war, BEFORE the German invasion of France.

[ACE-OF-ACES]

Has anyone bothered to log the TAS, Altitude, Throttle setting, etc in real time to a file during the CoD spitfire test flight?

And than compare that data to the real world data?

If not I would highly recommend that you do, because based on my experience most of the 'errors' people argue about are pilot errors during the test flight, not FM errors.

And the only way to be sure of that is to log said data in real time during the entire test flight, because something as simple as not holding a steady altitude during flight can have a big impact on the speed values.

[winny]

From the history of Trimpell Oil Refinery - Heysham. I'd love to know where they got the '384 Spitfires converted' from, would be interesting to find out.


The site was set up in 1939 as the Heysham Aviation Fuel Works to produce aviation fuel for the RAF. Using coke brought in from the Durham coal field together with imported gas oil, ICI produced the base petrol and ammonia while Shell produced iso-octane to boost the base petrol from 87 octane to 100 octane standard. Shell had found that the use of tetraethyl lead and hydrogen as fuel additives made it possible to suppress engine knock and to boost aircraft engine performance.

The plant at Heysham, together with those at Stanlow and Billingham produced iso-octane additives required to raise 87 octane fuel to 100 octane rating. Initially, the limited size of the 100 octane fuel stockpile required strict rationing until supplies could be increased to meet requirements and the 100 octane fuel was dyed green to distinguish it from the 87 octane fuel which was blue.
Bulk supply contracts for higher octane fuel were placed by the Air Ministry and it was put into widespread use in the RAF in March 1940 when Spitfires' Rolls Royce Merlin engines were converted to use the 100 octane fuel.

By May 1940, reconnaissance Spitfires had begun flying combat missions using the 100 octane fuel. By 31 July 1940, there were 384 Spitfires serving in 19 squadrons using the 100 octane fuel.

[VO101_Tom]

Originally Posted by klem

Thanks tom, it was just a thought.
(I think this is the link you meant http://www.spitfireperformance.com/spitfire-II.html )

Yes, this site.

[VO101_Tom]

Originally Posted by Osprey

I will have to read more on the top speeds since I am quite surprised that the 109E-1 is marked @ 302mph vs the Spitfire 283mph.

That is not even the top speed. Only 1:32 ata boost pressure ("climb and combat power"). The maximum performance ("start and emergency power") is 1:42-1:45 ata. This would be an additional 150-200 PS (~15-20%) engine power...

[Seadog]

Originally Posted by winny

From the history of Trimpell Oil Refinery - Heysham. I'd love to know where they got the '384 Spitfires converted' from, would be interesting to find out.

By May 1940, reconnaissance Spitfires had begun flying combat missions using the 100 octane fuel. By 31 July 1940, there were 384 Spitfires serving in 19 squadrons using the 100 octane fuel.[/I]

According to Dowding there were 19 Spitfire squadrons in RAF FC on July 08 1940:

http://www.ibiblio.org/hyperwar/UN/U...ette/37719.pdf (p4560-61)

but I'm not sure where the 384 figure comes from.

[Faustnik]

Originally Posted by ACE-OF-ACES

Has anyone bothered to log the TAS, Altitude, Throttle setting, etc in real time to a file during the CoD spitfire test flight?

This forum is interesting from the history discution. Some +12 data is really nice! Its to bad that so much RED vs. BLUE bs.

After the new patch we should do some testing.

[ACE-OF-ACES]

Originally Posted by Faustnik

After the new patch we should do some testing.

It would be nice if more people did before claiming the FM is too this or too that..

But I fear that will never will happen..

Which is why I decided to make my own website dedicated to performance testing, i.e.

www.flightsimtesting.com

Where I have created an online version of IL-2Compare, which allows you can compare one plane to another.

Right now all I have is IL-2 data..

But I am working on posting CoD and real world data..

Than you will be able to compare 'game' data to 'real world' data side by side in real time.

Basically all the stuff I have been doing for the past 10+ years in print outs people will be able to do in real time onilne.