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

[CaptainDoggles]

I like how you guys present letters that talk about planning to supply these stations with fuel as concrete evidence that they were supplied.

[*Buzzsaw*]

Originally Posted by CaptainDoggles

I like how you guys present letters that talk about planning to supply these stations with fuel as concrete evidence that they were supplied.

Actually we have linked multiple times combat reports and other documents showing RAF Squadrons based at these fields were using +12 boost and 100 octane.

Contrast with the Luftwhiner side, which has yet to provide a single document indicating any RAF fighter Squadron used 87 octane during the battle.

But of course, that's not surprising, that is the double standard the luftwhiners insist on.

[CaptainDoggles]

Your bias for the red side was established long long ago, Buzzsaw.

[Blackdog_kt]

Originally Posted by Crumpp

No, at any manifold pressure and rpm setting below the knock limited performance of the fuel, the power will be the same.

Basically at any manifold pressure below +9lbs (limit for 87 Octane) in the Merlin, the power is the same for 87 Octane or 100 Octane fuels.

This

Originally Posted by CaptainDoggles

The problem is that people think the higher octane fuels magically give more horsepower when in reality they merely allow the engine to develop higher power at higher manifold pressures without engine knock.

and this.

Originally Posted by Seadog

Kinda hard to keep formation if some aircraft are using 87 octane and some 100 octane...

In a Blenheim flying a long range recon or ferry mission (which is the only time they could use the auxiliary tanks) it is quite reasonable that there will be long periods where the expectation of enemy encounters are low, and thus mixing octane types is a reasonable risk. The problem is that it will take many seconds before the change back to 100octane can be made, and during that time overboost will not be available and damage to the engine may result if overboost is applied too soon.

Yes, it's kinda hard. And that's why whenever a squad was stationed on a field with available supplies of 100 octane they used that, when stationed on another one i guess they wouldn't.

The only case where you would have mis-matched fuel types in a single flight is if you diverted to another field using a different octane rating and then taking part in a scramble before going back to your own base.

Even so, maintaining formation is not done on full throttle anyway, so the point is moot. A flight leader will always fly slightly lower power settings than the nominal values for a very simple reason: if you're the first to take-off and start climbing (aka getting into a region of a higher TAS as you go along) it's increasingly harder for the wingmen to keep up with you if you are already running the maximum values.
Another reason is fuel economy, yet another one is that the faster you go the more pronounced any mistake is in station keeping.

Have you ever flown formation to the AI in IL2:1946 with their magic, non-overheating engines? If you did then you know what i'm talking about.

Since the amount of boost and RPM used is what governs produced HP, it's perfectly possible to keep formation even when using different octane rating fuel. The only case where a discrepancy would occur and aircraft would be spaced apart is when going to full power, because a difference in O.R. institutes a difference in what full power is for each aircraft. But then again, this happens in combat where (gasp!) it actually makes sense to loosen and even break up the formation, something the RAF realized early on after incidents where multiple losses were incurred because pilots were more busy keeping a close vic formation than actually splitting up and flying combat properly, so they switched their tactics.

In short, a different O.R. has minimal effect in how you keep formation because formations are not flown at full power.
You think too much in terms of pure numbers and totally sidestep tactical considerations and how a mission profile usually plays out. But then again, you're convinced it's possible to run engines on full WEP all day long, so i'm not surprised.


As for the Blenheim, yes it takes time until the residual fuel is burned up and there might even be a case of air in the lines when switching over from tank to tank, which is why it's standard procedure in many aircraft to turn on the fuel boost pumps whenever changing tanks and keep them running for a short while.

Also, full fuel was not only loaded for ferry flights. It was specifically used for long range raids, like the one on the Cologne power station. I have the actual pilot's manual and the main reason they used 100 octane in the first place was because the aircraft was too heavy to safely get off the ground with a full fuel load without the extra boost.

[Seadog]

Originally Posted by Blackdog_kt

.

In short, a different O.R. has minimal effect in how you keep formation because formations are not flown at full power.
You think too much in terms of pure numbers and totally sidestep tactical considerations and how a mission profile usually plays out.


.

I don't quite know how you managed to quote me without reading the extract where a pilot describes climbing in formation using overboost:

Quote:
P/O Art Donahue's account of using +12 boost during his first combat of 5 August 1940, whilst flying Spitfires with No. 64 Squadron out of Kenley, is typical:

“There are bandits approaching from the north” In quick response to this information, our leader sang out a command: “All Tiger aircraft, full throttle! Full Throttle!” That meant to use the emergency throttle that gave extra power to our engines. I was flying in our leader’s section, on his left. As he gave the command “Full throttle”, his plane started to draw ahead, away from me. I pushed in my emergency throttle in response to the command, the first time I had ever used it, and my engine fairly screamed with new power. I felt my plane speeding up like a high spirited horse that has been spurred. http://www.spitfireperformance.com/spit1vrs109e.html
Kinda hard to keep formation if some aircraft are using 87 octane and some 100 octane...

It was common for pilots to land and refuel at the most convenient base, then return to base and fly another mission, so if 100 octane wasn't universally used then there is a high probability that fighter squadrons would be forced into combat with mixed 87 and 100 octane fuel loads, yet there is no historical account of this ever happening.

Originally Posted by Blackdog_kt

But then again, you're convinced it's possible to run engines on full WEP all day long, so i'm not surprised.

It was possible, and was done on multiengined Merlin aircraft, when one or more engines failed. 12lb boost is not an excessive boost level even for a Merlin III, and as long as the cooling and lubrication stay in the black, the probability of failure is low:



Dover Castle to Hornchurch is ~55 miles, or about 11 minutes at 300mph, and this pilot was further east than Dover Castle..

[Blackdog_kt]

Originally Posted by Seadog

I don't quite know how you managed to quote me without reading the extract where a pilot describes climbing in formation using overboost

He didn't say anything about keeping station, he describes going full throttle in anticipation of an engagement. Neither of us knows if they were in formation at that point or if they had broken up to pick their targets, because the quote you supplied doesn't mention anything about it.

As for the rest of your post, 11 minutes is a reasonable amount of time (even though exceeding the specified guidelines) and a far stretch from all day long WEP running.

Let me ask you one question just to eliminate any suspicion of bias and restore my willingness to be convinced that your arguments are about what you perceive to be historically accurate and not about gameplay advantages: if someone finds combat reports stating similar situations for 109s, will you be content to let DB601s run WEP in a similar fashion (ie, with the only constraint being fuel expense)?

[Seadog]

Originally Posted by Blackdog_kt

He didn't say anything about keeping station, he describes going full throttle in anticipation of an engagement. Neither of us knows if they were in formation at that point or if they had broken up to pick their targets, because the quote you supplied doesn't mention anything about it.

As for the rest of your post, 11 minutes is a reasonable amount of time (even though exceeding the specified guidelines) and a far stretch from all day long WEP running.

Let me ask you one question just to eliminate any suspicion of bias and restore my willingness to be convinced that your arguments are about what you perceive to be historically accurate and not about gameplay advantages: if someone finds combat reports stating similar situations for 109s, will you be content to let DB601s run WEP in a similar fashion (ie, with the only constraint being fuel expense)?

I think that its pretty clear that the Squadron leader wanted them to climb in formation.

A Merlin III at 12lb/3000rpm will typically use 115 gal/hr. The maximum possible time for a Spitfire is 45 mins, and about 55mins for a Hurricane. Using say 20 gals for non boost operations, the max time for a Spit falls to 34 mins.

I suspect that info on WEP times for the Luftwaffe's engines must exist and I have no doubt that some of them could be run for extended periods at WEP, and it would be interesting to read such info. I have no doubt that an Me110 pilot might feel compelled to run at WEP for extended periods, when in combat with one engine out and multiengined Merlin powered aircraft had similar experiences, but a SE Merlin engined fighter doesn't have enough fuel to run for very long at 12lb/3000rpm.

[Glider]

I am afraid that I don't have the time I thought I was going to have but can quickly deal with the comment Kurfurst made about the Pilots notes for the Spit II.

There are two sets of pilots notes for the Spit II both of the dated June 1940 which is confusing. Kurfursts one states both types of fuel mine only 100 octane so there is an obvious queston as to which one applies at what time.
The decider I believe is in the other details in the pilots notes. The one Kurfurst quotes in section 35 and the gun controls goes into detail about how to choose the 20mm and/or the LMG's. The one that I have only talks about one firing choice withthe 8 guns specifically mentioned in item 44.

As we know the Spit II in the BOB was only armed with 8 x LMG so I believe that this is the one for the BOB period.

Twin fuel options for the 20mm cannon armed Spit II does make sense in early/mid 41, as the Spit II was quickly followed into service by the Spit V and the earlier Spits transfered to training roles which used 87 Octane fuel.

I attach links to both sets of notes for people to look at and comment on.

The version Kurfurst has
http://www.plane-design.com/document...e%20Manual.pdf

The Version I am referring to
http://www.ww2aircraft.net/forum/oth...uals-9050.html

So to sum up I believe that the 8 guns version with only 100 octane fuel is the BOB version. The 20mm gunned version with both 87 and 100 octane fuel is post BOB when in training command.

[Kurfürst]

Originally Posted by Glider

The version Kurfurst has
http://www.plane-design.com/document...e%20Manual.pdf

The Version I am referring to
http://www.ww2aircraft.net/forum/oth...uals-9050.html

I dunno what you talk about mate, this one you kindly attribute to me is a Mark Niner... and this isn't the one I talk about.

[Glider]

Kurfurst
Its late but I will comment on another of your points namely

The fact that the vast majotity of the fuel consumed was steadily 87 octane until the end of September 1940 (in agreement with Pips)

The important thing is the noticable increase in 100 Octane in September. Unfortunately we only have an average consumption figure for June to August of 10000 tons a month. I would expect the August figure to be very similar to September.

There is little doubt that the consumption of 87 Octane was broadly similar until the end of Sept 1940 (Paper Attached) but I wouldn't have expected anything else. The Other Commands were not given clearence to use 100 Octane until August 1940 (Paper attached) and it would have taken a little time to move the quantaties of fuel around.
In fact its noticable that in September the usage of 87 octane fuel started to fall despite the intensity of operations. The overall consumption figure, (combined 87 and 100 Octane) for August is almost identical to September 36,000 tons vs 37,000 tons but the 100 octane is going up and the 87 Octane down.

Remembering that the policy for the replacement of fuel in No 2 Group was to replace empty 87 Octane tanks with 100 Octane, the immediate effect would be little difference in the consumption of 87 Octane in late August / early September as the tanks are emptied, but a significant increase in the proportion of 100 Octane issued, to refill the empty tanks.