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

[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site you use as a source claims that the 1-min boost for the DB engine was not cleared until 1942, by when the Emil was withdrawn from service.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.

[Al Schlageter]

Oh dear, Kurfurst has gone on another one of his rants.

The Merlin in Perspective, no.2 in the R-R Heritage Trust's Historical Series

"Before the end of the Battle Spitfire IIs with Merlin XIIs were in service, with the supercharger gear ratio increased from 8.58 to 9.09:1 giving a better full throttle height at 12lb boost......"

[JtD]

Originally Posted by Kurfürst

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

You make it sound as if it was a useless option or a bad idea, but it is not. If it is combined with a decent overheat / engine damage model, it would imho be the best and most useful way of implementation in game. The engine could take 12lbs of boost, as we know from the take off setting, and disabling the automatic boost control would give the player a chance to manually set and maintain it. What it is not is a simple press a button solution. It is the minimum that was available historically, it's useful and interesting.

Thanks 41Sqn_Banks for the 17lb figure, I wasn't sure if other restrictions were in place before the 12lb modification was carried out. So I went with worst case.

[41Sqn_Banks]

Originally Posted by JtD

Thanks 41Sqn_Banks for the 17lb figure, I wasn't sure if other restrictions were in place before the 12lb modification was carried out. So I went with worst case.

About +17 is the amount of boost that the supercharger can produce at sea level, it's not restricted.

[JtD]

That I find highly unlikely, if it can produce +9 lb at 17000 feet, it should be able to produce about ((9+14)/527*1013)-14 lb at sea level, which is about +30 lb. The compression ratio should not change much. If it does happen, though, there's some sort of throttle in the way, and be it just too small cross sections somewhere between the intake and the supercharger.

(Note about the calculation: (9+14) - total pressure in the supercharger at full throttle altitude; 527 - outside pressure at full throttle altitude; 1013 - outside pressure at sea level; - 14 - to get from total pressure in the supercharger to overboost as used by the British)

[Osprey]

Originally Posted by 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.

Not with the Spitfire II which is what Kurfurst is talking about. This has a Merlin XII engine designed for 100 only.

I am not sure why Kurfurst agreed with you in the subsequent post unless he forgot which aircraft he was talking about

Originally Posted by JtD

A different system, bongodriver. It was limited to low altitude and could not provide boost at higher altitudes. Simply put, it had a full throttle altitude of 1000 feet, which would give you less than 9lb at altitudes exceeding 4000 feet. It's really just a take off setting.

I agree, I don't have a problem with that, but it's the clearance to use it I'm talking about.

When I was 18 I didn't have clearance to take my engine in my Ford Fiesta 1300S into the red all of the time but when my six was occupied by another kid in an Escort or Golf I pulled the tit and away we went down those country roads like dickheads. After a while I blew the camshaft out of the side of the block, I'm pretty sure Ford didn't recommend this.



I should scan a photo of my heap of crap, I would've killed for one of these.

[bongodriver]

Originally Posted by Osprey

Not with the Spitfire II which is what Kurfurst is talking about. This has a Merlin XII engine designed for 100 only.

I am not sure why Kurfurst agreed with you in the subsequent post unless he forgot which aircraft he was talking about



I agree, I don't have a problem with that, but it's the clearance to use it I'm talking about.

When I was 18 I didn't have clearance to take my engine in my Ford Fiesta 1300S into the red all of the time but when my six was occupied by another kid in an Escort or Golf I pulled the tit and away we went down those country roads like dickheads. After a while I blew the camshaft out of the side of the block, I'm pretty sure Ford didn't recommend this.



I should scan a photo of my heap of crap, I would've killed for one of these.

A fellow country road boy racer........My 2.0L Mk4 cortina was a beast.

[Osprey]

I read the rest. Firstly, Kurfurst, would you mind not ranting please, your post looks like it comes from a luftwhiner and you've lately managed to curtail that. As such people began to take you more seriously. Your comments about RAF fliers are offensive, when have you ever heard me rant about 109 boost use? My only complaint with your figures is that your graph is 30 kmph faster than any actual test and nobody can account for it - that's why you are in a constant argument and the only people who agree with you are the 109 fliers with an agenda for Spit bashing.

It should ALL be modelled for ALL types, then it's up to the pilot if he breaks it. In the future with scripting (and even now with Banks co-op) you will only get one flight, one life and one engine so fine - break it and die in the channel. Let's concentrate on getting 1C to model this as close to the evidence we have at our disposal as possible and use some damn common sense!