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

[TomcatViP]

Hi Bounder!,

The number of pages concerning the article (exception made of the 2 pages of adds) is only 3 pages p576 to 579. It seems for me that quoting the page was of no importance as I alrdy took great care of extracting for the reader AND in the same order what was the essential for the discussion.

That article was written at the occasion of the commemoration of 40 year of aero engine dev by RR and 50 years of History. The article is filled with 1 page add of RR. Obviously, we can understand that as it is today the article might hve been reviewed by RR !

The journalist of FLIGHT (H. F. K I N G , M . B . E) use a chronological order in his article and describe any major evolution of that engine IN THAT ORDER.

For example if he specified that 87 octane was the fuel grade in use at the time, when 100 oct fuel is introduced in an engine he noted the modification.

For example he clearly explains that if Hurri and Spits did rely on the Mk II and III, the Fulmar equipped with MkVIII could be fueled with 100 octane (with a max output power of 1080shp at T.O contrary to 1010 without - without meaning obviously with 87 ocatane ).

On point 1: yes we are talking abt 1937. It's the beginning of the article that deal chronologically with the Merlin story.

To say that the 87 oct fuel was the normal fuel used at that date I am using the quote on point 7 saying that using 100 oct fuel the Merlin XX had a 9lb boost
The date I mentioned (remark that I didn't re-use the 1942 date as in the FLIGHT article) is in perspective with the service introduction of that engine as in my own memory.

Note also that there is no mention of any use of the XX engine in the Spitfire but one on how the process of introducing that level of improvement was difficult ("These figures represent an
increase of nearly 250 h.p. over the Merlin II of identical cylinder
dimensions, and illustrate in a convincing manner the technical
progress achieved by years of 'toil, tears and sweat,' to borrow a
classical phrase from our worthy Prime Minister.")

All that makes sense to me on the base of technical grounds.

The quote made out of the rest of article are there to put the subsequent development in perpective regarding SHP and boost with the ultimate being 25lb for the post war 131/132 on the Hornet.

Hence we have two door in the Merlin history acording to the article : one in 1937 for introduction of 87 octane (confirmed in 1940 with the mention made of the Fulmar using a special engine) and the other in 1941 (42 in Fligt article) for possibility of 100 octane usage in the mkXX.

After that date it's upon the reader to decide witch fuel was in use since the article does not mention any switch (witch I found interesting despite all the other details of the engine modifications) but it's another story

Note also that in 1954, the merlin with 150000 units produced (all manufacturer included) represented more than 80% of all engines build by RR at the time (185000)

Source : http://www.flightglobal.com/pdfarchi...0-%201286.html

[Bounder!]

Originally Posted by TomcatViP

Hi Bounder!,

The number of pages concerning the article (exception made of the 2 pages of adds) is only 3 pages p576 to 579. It seems for me that quoting the page was of no importance as I alrdy took great care of extracting for the reader AND in the same order what was the essential for the discussion.

That article was written at the occasion of the commemoration of 40 year of aero engine dev by RR and 50 years of History. The article is filled with 1 page add of RR. Obviously, we can understand that as it is today the article might hve been reviewed by RR !

The journalist of FLIGHT (H. F. K I N G , M . B . E) use a chronological order in his article and describe any major evolution of that engine IN THAT ORDER.

For example if he specified that 87 octane was the fuel grade in use at the time, when 100 oct fuel is introduced in an engine he noted the modification.

For example he clearly explains that if Hurri and Spits did rely on the Mk II and III, the Fulmar equipped with MkVIII could be fueled with 100 octane (with a max output power of 1080shp at T.O contrary to 1010 without - without meaning obviously with 87 ocatane ).

On point 1: yes we are talking abt 1937. It's the beginning of the article that deal chronologically with the Merlin story.

To say that the 87 oct fuel was the normal fuel used at that date I am using the quote on point 7 saying that using 100 oct fuel the Merlin XX had a 9lb boost
The date I mentioned (remark that I didn't re-use the 1942 date as in the FLIGHT article) is in perspective with the service introduction of that engine as in my own memory.

Note also that there is no mention of any use of the XX engine in the Spitfire but one on how the process of introducing that level of improvement was difficult ("These figures represent an
increase of nearly 250 h.p. over the Merlin II of identical cylinder
dimensions, and illustrate in a convincing manner the technical
progress achieved by years of 'toil, tears and sweat,' to borrow a
classical phrase from our worthy Prime Minister.")

All that makes sense to me on the base of technical grounds.

The quote made out of the rest of article are there to put the subsequent development in perpective regarding SHP and boost with the ultimate being 25lb for the post war 131/132 on the Hornet.

Hence we have two door in the Merlin history acording to the article : one in 1937 for introduction of 87 octane (confirmed in 1940 with the mention made of the Fulmar using a special engine) and the other in 1941 (42 in Fligt article) for possibility of 100 octane usage in the mkXX.

After that date it's upon the reader to decide witch fuel was in use since the article does not mention any switch (witch I found interesting despite all the other details of the engine modifications) but it's another story

Note also that in 1954, the merlin with 150000 units produced (all manufacturer included) represented more than 80% of all engines build by RR at the time (185000)

Source : http://www.flightglobal.com/pdfarchi...0-%201286.html

You made broad statements claiming principally that 100 Octane fuel was not used by RAF fighter command during the Battle of Britain and to do this you used the article in Flight and listed quotes to support your argument. No where in that document is this stated at all i.e that 100 Octane fuel was not used during BoB.

The article covers the start of Rolls Royce and goes on to discuss the development of the Merlin engine. What I gather from your posts is that you are basing your argument that, when the Merlin II and III engines where first tested they used 87 Octane fuel, I have no problem with that. You are then saying that when the Merlin XX engine was introduced later in 1941 it ran on 100 Octane fuel, again I have no problem with that.

The problem I have with your argument is that it assumes Merin II or III engines could not or were not be modified to run on 100 Octane fuel – this is not stated in the article and is contrary to all the evidence posted in this thread and historical accounts showing that Spitfires and Hurricanes were converted to 100 Octane fuel before the Battle of Britain.

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PS: Thanks MoGas, I wouldn't post any scans if it could cause copyright issues.

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Just for the record, my concern regarding the whole 87 vs 100 Octane fuel stemmed from previous information that seemed to indicate at the time that CoD would not offer official models of the same aircraft with different octane fuel (link to post http://forum.1cpublishing.eu/showthr...439#post389439). My worry is that if only one octane model per aircraft will officially be supported that we will get official models using 87 Octane fuel without corresponding models using 100 Octane. Given the overwhelming evidence of 100 Octane fuel used by Spitfires and Hurricanes during BoB against the complete lack of evidence for those aircraft flying combat sorties using 87 Octane fuel, having official models only using 87 octane would, in my opinion, be historically inaccurate.

I understand that once the SDK pack is released players could model their own variants and I feel that if people want to model 87 octane Spitfires and Hurricanes that would be great and allow for more choice, particularly in dynamic campaigns where the LW successfully target enough RAF fuel supplies, bases etc forcing RAF fighters into 87 Octane fighters. Also, I don’t have a problem with variants of the Spitfires and Hurricane we have in game modelled officially with both 87 and 100 Octane, then it’s up to the user / mission designer to pick. But if we can only have one variant per model, then it should in my opinion be the 100 Octane variant since all the evidence supports 100 Octane fuel use in BoB.

[TomcatViP]

Originally Posted by Bounder!

You made broad statements claiming principally that 100 Octane fuel was not used by RAF fighter command during the Battle of Britain and to do this you used the article in Flight and listed quotes to support your argument. No where in that document is this stated at all i.e hat 100 Octane fuel was not used during BoB.

If it was not used no one will tell that it has not seen any use... C'mon ! DO you see flying car in the street ? What would you think if someone will tell you 70 years latter that car were flying as there is no proof of the contrary and that no one at the time as wrote that cars were not flying (for the future generations : I AM WRITING THIS IN THE EARLY 2012 AND CAN TESTIFY THAT NO CARS ARE FLYING AT THIS STAGE !) ?

humm remind me a movie with some monkeys, Bruce Willis and Brad Pitt

Originally Posted by Bounder!

The article covers the start of Royals Royce and goes on to discuss the development of the Merlin engine. What I gather from your posts is that you are basing your argument that, when the Merlin II and III engines where first tested they used 87 Octane fuel, I have no problem with that. You are then saying that when the Merlin XX engine was introduced later in 1941 it ran on 100 Octane fuel, again I have no problem with that.

I didn't say that - I said that the article write that once used with 100oct MkXX had a boost level of 9lb (what is confirmed by some source alrdy posted). Pls re-read the article

Originally Posted by Bounder!

The problem I have with your argument is that it assumes Merin II or III engines could not or were not be modified to run on 100 Octane fuel – this is not stated in the article and is contrary to all the evidence posted in this thread and historical accounts showing that Spitfires and Hurricanes were converted to 100 Octane fuel before the Battle of Britain.

If it was the case, RR would have asked this to be included in that article and FLIGHT would have been proud to put that fact in their story.

Originally Posted by Bounder!

But if we can only have one variant per model, then it should in my opinion be the 100 Octane variant since all the evidence supports 100 Octane fuel use in BoB.

That's an adventurous conclusion !

If they didn't make any mention of such "conversions" it's not because they wanted to hide it to the future WWII simmer of the early 21st century but perhaps because there was no such usage.

In the Au archive we have alrdy seen that 100 octane fuel was used to be blended with old stock of 74 octane fuel to produce 87, 90 or even 95 octane fuel.

Last but not least, when used in the MkVIII engine, the 100 octane fuel was not producing tremendous amount of extra power (1010 vs 1080).

[Osprey]

Originally Posted by TomcatViP

If it was not used no one will tell that it has not seen any use... C'mon ! DO you see flying car in the street ? What would you think if someone will tell you 70 years latter that car were flying as there is no proof of the contrary and that no one at the time as wrote that cars were not flying (for the future generations : I AM WRITING THIS IN THE EARLY 2012 AND CAN TESTIFY THAT NO CARS ARE FLYING AT THIS STAGE !) ?
humm remind me a movie with some monkeys, Bruce Willis and Brad Pitt