Spitfire & Hurricane flight model & engine performance thread. (1.09 patch)

[Kurfürst]

I think it was discussed and shown that +12 combat rating was cleared for the Merlin XII only well after BoB, though there was some sort of take off rating that was pretty much useless for anything else but to shorten takeoff.

[Al Schlageter]

Originally Posted by Kurfürst

I think it was discussed and shown that +12 combat rating was cleared for the Merlin XII only well after BoB, though there was some sort of take off rating that was pretty much useless for anything else but to shorten takeoff.

The BoB was just starting in July 1940.

The Spitfire II Pilot Notes, dated July 1940, say 12lb boost can be used to 10,500ft. A boost of 12.5lb can be used for take off to 1,000ft.

http://www.zenoswarbirdvideos.com/Im...pit2Manual.pdf

[JtD]

I'm afraid zeno is inaccurate here. I think I have the Spitfire II pilot notes without any amendments, at least the amendment list is there and empty. This should be the original version dated July 1940. In there, the engine limitation for all out level is 9lb boost.

It appears that the all out level increase was at latest added with amendment list 31 / L, at a date that is not known to me.

The zeno version is missing the amendment list and does not shed any light on the "when".

[Osprey]

It doesn't matter. If you had a 109 on your backside or gave chase then you'd hammer the thing. I'm pretty sure that most 19 year olds don't drive 'according to approved ratings' but it doesn't mean it can't do it

[JtD]

It does matter, because it was necessary to modify the automatic boost control in order to have it deliver 12lb when in override. It would always have been possible to override it, but in the worst case you could end up with boost exceeded 30lb and destroy the engine instantly.

[Kurfürst]

Indeed JtD.

[bongodriver]

And there you have it....12lbs boost up to 1000' for take off or for a maximum of 3 minutes otherwise.

I'm sure nobody is suggesting 3 minutes was used to get to 1000'

[fruitbat]

Originally Posted by Kurfürst

I think it was discussed and shown that +12 combat rating was cleared for the Merlin XII only well after BoB, .

No it wasn't.

No one knows what date the amendment was from the discussions here, and you can't say with any certainty when it was cleared without the date of the amendment, all we know is it was after july'40 sometime.

It could of been in September for all we know or well after BoB, without the date, its just speculation, so don't spread you want to believe as fact.

[41Sqn_Banks]

First documented use of emergency boost with a Spitfire II is 21 August: http://www.wwiiaircraftperformance.o...-21aug40-1.jpg

Double standard view on the subject:

The use of +12 in Spifire II is
a) documented in combat reports as "emergency boost" 8 days after the first operational use
b) authorized in a later edition of the manual
c) the cut-out is mentioned in the earliest edition of the manual for emergency use. Without a specific modification to +12 boost the cut-out would enable the pilot to obtain any boost up to +17
Invalid. Not enough proof, even if there is nothing that prevents the pilot from using it. The combat report doesn't mention +12 boost, maybe the pilot used the cut-out to obtain the regular boost +9 manually instead of simply moving the throttle full forward.

On the other hand there is 1.4/1.45 ata for DB601A which
a) is restricted to take-off in any edition of the manual
b) is not mentioned by any pilot report for anything else than take-off
Valid. There is nothing that prevents the pilot from using it in combat.

[Kurfürst]

Originally Posted by 41Sqn_Banks

First documented use of emergency boost with a Spitfire II is 21 August: http://www.wwiiaircraftperformance.o...-21aug40-1.jpg

Double standard view on the subject:

The use of +12 in Spifire II is
a) documented in combat reports as "emergency boost" 8 days after the first operational use

Wishful thinking. It doesn't say +12 lbs boost, it says 'emergency boost', which we all know was +9, as per the manual. Selective and wishful use of evidence...

b) authorized in a later edition of the manual

And as such irrelevant for BoB period. Same site you use as a source claims that the 1-min boost for the DB engine was not cleared until 1942, by when the Emil was withdrawn from service. It also claims a gazillion other BS for LW planes and has achieved an unenviable reputation for bias and manipulation as a result.

c) the cut-out is mentioned in the earliest edition of the manual for emergency use. Without a specific modification to +12 boost the cut-out would enable the pilot to obtain any boost up to +17

So by all means model the boost cutout and enable pilots to obtain +17 lbs boost and blow their engines at free will...

On the other hand there is 1.4/1.45 ata for DB601A which
a) is restricted to take-off in any edition of the manual

In contrast of +12 boost being physically restricted (impossible) on the Spitfire II. Nothing restricts the use of 1.4/1.45ata in the 109/110/111, expect for the 1-min clockword which is already present and modelled.

b) is not mentioned by any pilot report for anything else than take-off

Show me say 10 German pilot reports then which 'does not mention it'. No, you have not seen ANY, you just make up an arguement, neglecting the fact that German pilot reports never seem to mention any boost levels during the whole war, and here's why - unlike the British, they had automated systems since the start of the war, so boost levels were meaningless to their pilots - they did not have to set it separately. Neither they needed to overboost woefully undersized engines to compete and thus it was utterly irrelevant to pilots.

Let me show you a real example of double standard.

RAF fans like yourself wish to have a plane modelled in the sim after a crayon graph they drew up themselves in desperation as there is curiously not a single +12 lbs boost report being made, so they had to make up one and wave it around. Ring a bell?

RAF fans like yourself wish NOT to have a plane modelled in the sim after a doucmented and guaranteed tests just because it shows that their cherished RAF plane with much larger drag and 25% greater wing area is, horriblle say, was slower than the blue plane with more power and less drag at sea level.

Said RAF fans then come to the forums and complain about a German rating that was there, and ask for a RAF boost that wasn't there, and wish to model that boost based on no performance test at all.