Bug 174 on 12lbs boost. Review please.
 

I'm about to update bug #174 on the Merlin 100 octane issue. I have re-written the bug for Artist as requested and would like a review. Kurfurst and Crumpp will be ignored, I am interested in ratification from one or more from Glider/Banks/NZTyphoon/Robo/lane. If this is ok I'll post the update, if there is anything I can add such as a good graph or table or test please post. Thanks.

Description
Presently if the Automatic Boost Control (ABC) is pulled on Spitfires and Hurricanes and full throttle applied there is no increase in boost above 6.25lbs even when the ABC is enabled. This results in reduced and inaccurate performance of RAF fighter aircraft.

During the BoB all frontline fighters had been modified to use 100 octane fuel in their Merlin II and III engines which allowed the engine to achieve 12lbs boost under strict limits. The Merlin XII engine fitted to the Spitfire II was designed to use this fuel from the factory. The approval and introduction of these changes gave the RAF fighters a performance boost in top speed, acceleration and rate of climb up to the Full Throttle Height (FTH) of about 18,000ft. At sea level a Spitfire was about 30mph faster when the ABC was enabled.

Merlin II and III (fitted to Spitfire Ia and Hurricane Ia)
The Merlin engines have a mechanical supercharger and can deliver up to 20lbs of boost at S.L. with the throttle valve fully open using either 87 or 100 octane fuel however this would cause serious engine damage by pre-detonation in the cylinders. Because of this the Merlin II and III have a boost controller fitted which limits the boost to only 6.25lbs. With modification to use 100 octane fuel the pilot could achieve 12lbs boost by pulling the Automatic Boost Control increasing the ‘safe’ power that the engine could produce. When the pilot applied the ABC on the Spitfire a thin wire was broken to indicate to the ground crew that ABC had been used and to make necessary checks. The Hurricane had a valve which was pulled (“pulling the tit”)

Merlin XII (fitted to Spitfire IIa)
The Merlin XII did not require modification in order to use 100 octane fuel. It had a slightly different throttle system and used a ‘gate’ on the throttle control. This allowed the pilot to achieve 12.5lbs boost on takeoff and is allowed up to 1000ft when he moved the throttle past the gate. Up to the gate 9lbs boost was achievable up to the FTH of 17000ft and later clearance was granted to use 12lbs boost (see pilot notes) There are lots of combat reports supporting this.

Here are the engine power ratings for given boost vs altitude
http://www.spitfireperformance.com/merlin3curve.jpg

Spitfire Ia prop tests using 6.25lbs boost and 87 octane
http://www.spitfireperformance.com/spitfire-I.html
It contains information on the clearance and usage of 100 octane fuel including this graph for the Spitfire Ia using 12lbs boost
http://www.spitfireperformance.com/s...-rae-12lbs.jpg

Here is the performance test for the Hurricane Ia using 100 octane fuel and 12lbs boost
http://www.wwiiaircraftperformance.o...rricane-I.html

Here is the performance for the Spitfire IIa
http://www.spitfireperformance.com/spitfire-II.html
Note that the boost for the tests is 8.8lbs, that is up to the ‘gate’ and this falls away from 17,500ft, the FTH.

Pilot notes for the Spitfire IIa indicate the limitations
http://www.spitfireperformance.com/spit2pnfs3.jpg

This report is evidence for the approval of 12lbs/100 octane prior to the Battle of Britain start
http://www.wwiiaircraftperformance.org/ap1590b.jpg

This is supported by lots of evidence of its use in combat reports (supplied by others in this bug report)

These reports not only supply data on the speed per altitude but also rate of climb and acceleration, plus some information of spin characteristics, dive ability and rate of turn. This should all be used to improve the current flight models for RAF types.

looks good to me

- IIRC ABC stands for "automatic boost control" and not the cut-out.

- Spitfire II had "gate control" for fixed take-off boost (it gave a fixed throttle valve setting) and "boost control cut-out" like the Spitfire I, see this thread: http://forum.1cpublishing.eu/showthread.php?t=31319

I think 1C will be as stubborn about this as they were about the FW190 bar in il2.

Could you add any indications of the duration for which running at 12lbs / 12.5 lbs was allowed? They would have to model engine damage if the time was exceeded and is essential for any correct FM/DM

The official limit was 5 mins but there was nothing to stop pilots going for a lot longer than that. Dowding issued a memo to all pilots that warned them of overusing the boost. In some of the combat reports you sometimes see words along the line of switched guns to fire, lowered the seat and pulled the plug.

@Banks: Thanks.
@Stormcrow: Pilot notes specify the limits.

Wow. That's a wealth of information that you have accumulated there Osprey.

I have an original Air Publication 1565A "The Spitfire I Aeroplane Merlin II Engine" manual which I thought might be useful - but I think those references you have must cover it all. I went through it specifically looking for performance charts but unfortunately there are none. There are change bars around the fuel and pitch sections though... and it states:

Fuel ....... Specification D.T.D.230
Note:- 100 octane fuel may be used, if the engine has been suitably modified.

Under the Automatic boost control it does mention +12lb/sq.in at sea level but does not tie this to 100 octane fuel.

Just had a speed test in the Rotol Hurricane. Couldn't get more than 230mph ASi out of it, trimmed, level flight, at various RPm (best 2650). According to this:

http://www.wwiiaircraftperformance.o...rricane-I.html

I should get 261mph with the Rotol which is 290mph TAS.

i have a feeling as well that we will not have correct speed performance for these engines for a while.

I applaud the efforts of you and others to try and keep this issue near the forefront... 1C needs to get it right.

Same feeling. The tendency of the last beta patch is clear. Instead of improving the performance of all planes minus the spit 2 they degrade the spit 2 and the hurri. Even though now relative performance is restored historic wise we are now further from historic absolute values. I wonder if this is an integral part of the strategy in the light of the upcoming sequel.

(ok, I may be simplifying a bit but overall this is the tendency how I see it)

I am more than a little concerned at the thought of a sequal built on sand.

261 IAS converting to 291TAS is a huge difference at sea level. 30 Mph diff is not feasible.

Apologies IvanK, I missed you off the list to review my OP, please advise anything you think is incorrect.

Regarding your comment though, what do you mean by 'not feasible' in this context? You mean it just shouldn't happen because it is a lot? Trouble is it is actually worse than just 30mph because this is WITHOUT 12lbs boost, so you can add another 25mph to that figure. Essentially the Hurricane is 50-60mph too slow. When I looked at the graphs too the 109 is faster than RL up to 6km too, so we have an inaccuracy of around 80mph!!

No probs. Regarding the comment on speeds I am only referring to getting 291MPH TAS from an IAS of 261MPH. At Sea Level IAS is going to be pretty close to TAS +- a nanofart.

I agree just about every RAF fighter is too slow in the patch at sea level.

(Check PM in about 10 mins)

On the graphs posted by BlackSix the 109 is actually a hair bit slower than real life specs.

Not with WEP on it isn't.
http://www.sukhoi.ru/forum/attachmen...3&d=1334842797

Spitfire 1a is faster than 109 with or without WEP above 6000m after the patch.

What exactly is the problem?

To my understanding the 109 is definitely very much slower than RL at altitudes above 5500m, at 7000m by 30-40 kph. That is a huge discrepancy. As far as I can read kyrillic letters (I am learning Russian a little bit) the blue curve shows RLE values (so flight tests by the British), the purple one says something like "igra forsash" (= game XYZ?) and the grey "igra bez forsasha" (= game ....?)

My guess is that the purple line is post patch the grey pre patch. the purple line is following the grey line (just beneath it) from alt 5200m.

Purple line is with WEP. Форсаж (Forsazh) translates roughly to "boost". Без Форсаж (Bez forsazh) translates to "without boost" therefore grey line is without WEP.

Thanks. It is still too slow at high alt compared to RLE data.

I checked 109 sea level speeds and nothing change comparing to pre beta patch version.

So i think there is no changes in FM of 109 ( also there is no info about it in beta patch notes). So still 109 is to slow ab. 20 km/h at 1.3 Ata power and ab. 20 km/h at 1.4 Ata - so generally 40 km/h slowier at the deck.

Moreover i checked british fighters in beta patch and i got:

Hurricane MK 1 Rotol

238 mph /383 kph at the deck at +6 1/2 boost ------ should be 262-265 mph /420-426 kph !!!!

So it is 24-27mph/ 38-43 kph too slow at + 6 1/2 boost power !!!!

There is no WEP - so no 100 octan fuel performacne - which should give ab. 25 mph/ 40 kph extra speed at low alts

Spitfire MK1a

255 mph at the deck at 6 1/2 boost ---------should be 283 mph !!!!

So it is 28 mph/45 kph too slow at 6 1/2 boost.

No 100 Octan fuel performance at all - boost cut out doesnt rise power at all.

Spitfire MK II

268 mph at deck at 6 1/2 lbs
285 mph at deck at 9 lbs ------ should be 286-290 mph so it is very accurate result!!!!

Still no 100 octan fuel performance - so no emergency +12 lbs.

There was no WEP for DB601 A1/Aa, only a special take-off boost. There is nothing that indicates that 1' Minute 1.4/1.45 was used for anything else than take-off or above 1-1.5 km altitude.

http://www.il2bugtracker.com/issues/40#note-10
http://www.il2bugtracker.com/issues/40#note-11

Kwiatek, are you just really good at keeping the stick level or is there a trick? I want to test at FTH but I have trouble keeping the aircraft steady.

Maybe I need to decrease sensitivity on my trim controls.

Try not to move your hand so much. I realise that it's so used to vigorous movements that it's tough for you, but I reckon you can manage it if you concentrate enough.

Are you upset that I called you out for trying to misrepresent a historical quote?

On the other hand there is nothing to suggest that 1,40/1,45 ata was not possible use at any altitude. So far I have not found any evidence that this was mechanically restricted to the 1st supercharger speed, and it quite likely that it was not.

OTOH I agree that the manuals insist that is to be used for special take off conditions. Which is kinda parallel to the Spitfire II limitations (which limit +12 to take off conditions only), so it just might be good idea to include a code that this 'WEP' on both planes should be only usable when the wheels are on the ground.?

It depends on how 1C interpreted 'WEP'. Is it referring to the 5-min 'Vollast/Kurzleistung' (1.35/2400) or the 1 min 'erhoehte Kurzleistung'?

In the former case, if the 1C WEP is equivalent to the historical 5-min rating, 500 km/h on the deck is correct and historically accurate result.

If however they understand WEP as the equivalent of the historical 1-min rating, there is a rather mixed situation: you can indeed reach the historical top speed, but as Banks have noted, by using a rating that was historically prescribed to special takeoffs.

Hi Kwiatek,

I did some trials both online (ATAG Server) and offline with the Spitfire Mark Ia and IIa. The online flight model does not match the offline flight model for the Spit IIa at altitudes of 5,000 and 10,000 feet.

For the Spit IIa, going into full overboost at 2800 rpms I recorded the following IAS (mph) at the different altitudes:

Sea level: online 292 ; offline 288
5,000 feet: online 270 ; offline 288
10,000 feet: online 262 ; offline 290

The methodology was simple: fuel 100%, radiator 50%, trim for level flight at designated altitude, then fly level and record direct off airspeed indicator.

Bizarrely, the Spitfire Ia showed a slight dip in IAS at 5,000 feet, then a small increase at 10,000 feet (online), offline it simply showed a significant decrease in IAS at 10,000 feet.

When adjusting prop pitch to 3,000 rpms at full overboost the Spitfire Ia showed a slight increase in speed at all altitudes tested, but the Spitfire IIa consistently blew its engine at the higher altitudes, although the same online difference in speed vs the offline speed was likewise reflected prior to engine failure.

The majority of combat online (ATAG Server) currently occurs at 10,000 feet or less, even with bomber streams at 11K - 14.5K. Airfield suppression (vulching) is permitted on ATAG which drags the action down to sea level, but steps are being taken with mission design & scoring to strongly encourage both sides to take the fight realistically higher -- much higher.

I was skeptical when I first heard of differences between the online and offline flight models until I actually tried them myself. I certainly encourage anyone to try this themselves, especially with other RAF and LW aircraft.

I've included the data I recorded (attached).

Sadly I think getting that answer out of them might be difficult. The "afterburner" function in-game ( :rolleyes: ) doesn't last anywhere close to 5 minutes, so I would guess they're interpreting it as the 1-minute "increased short-term performance".

It is easly readable on ATA guage where it show after WEP button - 1.45 Ata power - so 1 minut take off power.

Moreover most know German and other county test for serial 109 E planes are very close and showed 467 km/h at deck for 1.3 Ata power ( 5 minute emergency power). So for 1.35 Ata it should be just little faster - a few kph.

Kurfurst think that 109 E was such fast like 109 F-2 but if he belives that Emil has similar speed like more aerodynamical cleaning plane with better enginehe is really not serious man for me :cool:

I have already explained that the test you have showned are undoubtedfully showing only Hoehenlader performance (ie. for our English friends using FS gear - that was optimized for high altitudes - for all altitudes, and it will naturally show lower results at low altitude.)

Correction: Messerscmitt AG thinks that, based on flight test results. And it was so certain about that contracted for about 4000 planes at around 50 000 Reichsmarks each, all reaching 500 km/h at +/- 5% tolerance. That means that Messerschmitt AG would loose about 50 000 Reichsmarks on each 109E that did not reach at least 475 km/h, the absolute minimum. The one the French tested reached about 485 iirc, albeit at only 1.3ata.

The 109E was not as fast as the F-2, the F-2 was rated iirc around 515 kph, the E-1/3/7 at 500 kph. The major difference is not only the engine, or the aerodynamics, but also the propeller. The Emil had a very different propeller one with larger diameter, and had distinctly different propeller effiency than one mounted on the F-2. Even between later G-14 and G-14/AS (different propellers) there was about 10 km/h difference in favour of the G-14 with a low-medium altitude propeller at low altitudes, despite both aircraft having exactly the same amount of power available - 1800 PS.

As for the 109F's aerodynamically more favourable shape, yes it was but it seems its rather overrated. Much of the higher top speed came from the fact that the 601N fitted to the F-2 had much much better altitude output than the 601Aa in the Emils. My studies indicate that the aerodynamic improvements amounted alone for about 15-20 km/h top speed (which is BTW excellent for an aerodynamic improvement)increase, the other 20-25 km/h was entirely down to the increased engine outputs and as noted, the new propeller.

It's hardly a unique situation anyway, the early Spit Vs were much slower than Spit Is at low altitudes, early Spit IXs were again slower than the latest (uprated boost) Spit Vs at lower altitudes etc. High altitude performance was more important for everyone, and propellers can't be just as good in both dense air (low altitude) and thing air (high altitude).

But you know what write a letter to MBB and tell them that you do not like their precedessor's 1940 specs at all. ;)

The take-off boost in Spitfire II was provided by a "gate control" which caused a fixed throttle valve setting, thus boost would fall off quickly with altitude (the throttle valve didn't open progressively to maintain the take-off boost)*.
The boost control cut-out on the other hand opened the throttle valve progressively to kept the +12 boost until it was completely opened, thus emergency boost was maintained up to FTH.

The DB601 manual indicated that for the take-off power the throttle valve is opened slightly more than under normal condition. This would theoretically allow to use 1' Minute boost up to FTH.

* with increasing altitude the throttle valve would again open progressively to keep +9 boost as the throttle lever is logically in the most forward position, but as we know it should only be used up to 1,000 feet this would normally not occur.

Thx for the explanation, Banks. Regardless of the lack of mechanical restriction on the 109E, I think our virtual selfs should be limited by what was authorized and how. At least the manuals set these limitations out in clear-cut manner to which I believe most pilots had adhered.

Otherwise its a very swampy terrain we are heading. Field mods this, field mods that, weren't really followed in the field, yes it was, no it wasn't.. you get the point.

I think the only bad thing that would happen in the DB601 is excessive engine wear, much like the use of take-off or emergency power for Merlin engine.

The explanation for Gate control comes from: http://www.enginehistory.org/Piston/...erlinABC.shtml

Agreed about the virtual limitation. It would be the best if take-off boost settings simply wouldn't provide a increased boost above their limiting altitudes. The engine seems to be able to handle this, as can be seen in the speed graphs of Blenheim and Fiat G.50 (I didn't test so far what happens if take-off boost is used above that altitude in these planes).

Alternatively engine damage could be forced above these altitudes, much like the GM-1 restriction from old IL-2. But I guess this would be incorrect in most cases.

It seems to me that the historically available boost/overboost capabilities should be modelled for all aircraft whether their use in any particular circumstance was authorised or not. Any pilot having the need to save his backside would use whatever was available to him, authorised or not, and I can't see Dowding, Park, Molders, Galland or anyone else ripping into a pilot for damaging his engine to save his life.

CEM should be used to damage the engine if the prescribed time limits, or perhaps an increased % of the time limits like 125%, were exceeded as that is the only way we have of bringing some kind of limitation to its use and representing engine damage. CEM already does this to Merlin engines if max boost and rpm are maintained for too long although I haven't tested what those limits are.

When we have finally a reasonable scoring system online and a reasonable career mode I'd suggest that all pilots violating engine wear limits get penalties on online score and career progress offline.

That's actually a pretty interesting idea for online wars.

I was just thinking about the same thing! :)

This might be a dumb question but has anyone asked the question of 100 octane availabiliy during BoB at the Imperial War Museum at Duxford?

But what for??

There is no question that 100 Octan fuel was used during BOB.

Not according to Herr Kurfaust. And the "discussion" is about how common it was. If "a lot" or "most" squadrons used it then surely it should be in the game?

Really dont care Herr Kurfurst. He is known 109 fanboy and it is really hard to call him objective in such case regarding 109 vs Spit performance.

Im sure 100 Octan performance for british fighters should be implement in game.

I wonder why I voted for the inclusion of 100 octane in the bugreport forum. Oh, yes, I forget, I am a mindless fanboy. :D

Mind you he's still spamming the bug report with rubbish so it's quite clear that Barbi has a fixed agenda and is trying to ensure that the message about 100 octane and +12lbs boost is scrambled and confused for the developers. He's still trying to present the spurious "Pips papers', which he has never seen, as "evidence" that the RAF only allocated the fuel to a select few frontline fighter squadrons. Pathetic and laughable. :grin::grin::grin:

I post the evidence I have on a thread which is about collecting all the evidence to be reported to the developers.

NZTypoon and Osprey wanted to keep that evidence away from the developers, now asking the evidence to be removed and present only filtered evidence.

A verdict on this is easy to make.

IMHO most of your comments are very valid and add some evidence that were not presented in the bug report so far. I don't understand why they should be removed, especially as they support the request for +12 boost.

- They clearly show how the amount of issued 100 octane increases during and eventually overtakes the issued of 87 octane.
- They show that selected stations (Bomber Command stations with Blenheim and Fighter Command stations with Hurricane and Spitfire) received 100 octane in May 1940.

Regarding the opinion of Pips I'm sure we all will be glad to consider the the "Pips papers" as a valuable evidence as soon as they are found and properly sourced.

I know 'Pips', who is a member of this forum, absolutely rushed to validate the existence and authenticity of the papers he claimed to have discovered when asked, very politely, by others to participate in the thread pertaining to 100 octane fuel...but then again a second hand summary of papers Barbi has never seen on a seven year old thread which is closed to non-members of that particular forum is more than enough evidence to prove anything. :rolleyes:

IMHO the 'Pips papers' fit in well with the current trail of evidence. After all the May papers as you noted tell of the issue of 100 octane to the selected stations (which is what Pips is saying, though he quantyfies it at 25%).

He notes that the situation eased in August with the arrival of the first Middle East fuel shipsments. This is again reflected in the August 7 memo posted which notes 100 octane is now cleared for all operational aircraft.

The fuel issues again show the issues increased in the automn, especially end of September which is again line with the 'Pips paper' and Pips statements.

I wouldn't be surprised if Pips would have found the same papers, but had an access to a more complete trail of papers, than what is Glider/lane has been willing to disclose to us. Nota bene that Pips shared his findings some 8 years ago, well before Glider had seen these documents himself.

But this has been done to the death. The devs will decide, but indeed the papers I have posted definitely support the need for the addition of RAF 100 octane variants.

@Ospey I'd like to rephrase some sentences in the initial post. The changes sentences are in bold.

Emergency / Combat boost was +9 on the Spitfire during the BoB, not +12.

Utter nonsense, of course

http://www.spitfireperformance.com/ap1590b.jpg

http://www.spitfireperformance.com/dowding.pdf

http://www.spitfireperformance.com/lane-26-5-40.jpg

http://www.spitfireperformance.com/webster-28-7-40.jpg

http://www.spitfireperformance.com/gribble-12lbs.jpg

http://www.spitfireperformance.com/elliott-9-9-40.jpg

http://www.spitfireperformance.com/McMullen-15oct40.jpg

Correction: Spitfire II limitations for BoB were +9, not +12.

See:

http://forum.1cpublishing.eu/attachm...8&d=1335381803

I am sorry but you're wrong. +12 was used in Spitfires Mk.II during BoB.

And the source for that..?

The use is reported on:
- 21 August 1940 http://forum.1cpublishing.eu/showpos...postcount=1441
- 2 and 30 November 1940 http://forum.1cpublishing.eu/showpos...8&postcount=55

The page from the Pilot's Notes is from June 1940. Spitfire II entered service on 13 August 1940.

Only mentions "emergency boost", at 4000 feet, does not specify boost used/obtainable.

Only mentions "boost cut-out", at 4500 feet, does not specify boost used/obtainable.

And the point is?

+12 lbs boost was only usable for take off and at low altitudes, and it fell of rapidly, in contrast to Spitfire I pilot notes which notes its effective up to rated altitude. There was no 'two different' sytems on the Spitfire II during BoB.

See:

AP 1565B, Vol I, Section 8 was issued in August 1940 and mentions the "two different" systems. "6. The quadrant plate has a ... gate for the throttle lever in the take-off position". And in paragraph 7 mentions that the "red-painted thumb lever can be pushed forward in emergency".

Now how would they technically do that, make the boost of 12" drop off quickly instead of having it follow the outside pressure? What did the automatic boost control cut out do on the Spitfire II if not disable automatic boost control?

To my understanding (please correct me) of the pilot's notes page posted:

During take-off EITHER 3000 rpm OR 12 lbs boost + 2270 rpm up to 1000ft alt or for 3 mins ?????? (which indicates that 12 lbs boost could be used beyond 1000ft but only for 3 mins, but at lower rpm???)

30 min climb: max boost 9 lbs + 2850 rpm

cruising 7 lbs + 2650 rpm normal mixture
cruising 3 3/4 lbs +2650 weak mixture (fuel saving)

all out : 9lbs + 3000 rpm for 5 min

max dive for 20 sec: 9 lbs + 3600 rpm (cooking your engine quickly I imagine)

2270rpm is the minimum to prevent engine damage, 3000 was the proper setting.

Ah thanks. I did not read minimum:

so

for take-off they say:

rpm in between 2270 and 3000 with max boost 12 boost either up to 1000 ft for extended time or up to 3 min.

They are the same. The throttle had a section for takeoff gate postion, and the "Red painted thumb lever" covered that position as safety switch, physically preventing the throttle to be pushed into the take off position until it was pushed forward.

Hence the confusion. The manual itself does not describe any two different systems.

As I understand, the cut out as its name suggest disabled to automatic boost control and gave direct control to the pilot over the boost. Maximum forward position on the throttle was set to open the cross section for +12 lbs at SL, and naturally this fell off with altitude; the pilot would have to open even further to compensate, which was however physically impossible - the throttle could not be pushed even further, it was already in the end position.

This graph suggest (see boost falling) that +12 fell back to +9 within about 2500 feet. This would also suggest that using the boost cutout was quite useless above that altitude, since it gave you the same performance as not using it at all.

http://www.spitfireperformance.com/p7280-speed.jpg

Come to think of it, it seems to work exactly the same as the 109E's 1-minute rating, altough that latter was automated.

Please explain how the red painted thumb lever was able to physically prevent the throttle to advance into the gate position.

http://forum.1cpublishing.eu/attachm...4&d=1336907008

Exacly +12 lbs up to 1000ft or up to 3 minutes. Merlin XII was initialy adopted for 100 Octan fuel not like Merlin III which required modification. Im sure that in SPitfire MK II was allowed for +12 lbs for emergency for short time from the begning. ( initialy up to 3 minutes later up to 5 minutes).

http://www.spitfireperformance.com/spit2pnfs3.jpg

In the override position...? ;)

Use your imagination a bit where that little thing just above the "Push" sign goes when the red painted thumb lever is rotated back. ;) Yup, it prevents the throttle from being pushed into the takeoff gate.

The "gate control" set a fixed throttle valve position. Indeed this was not adjusted by decreasing atmospheric pressure and thus would fall off with altitude as you describe.

The "boost control cut-out" did not set a fixed throttle valve position. The position was directly controlled by the pilot but limited the opening of the valve that +12 boost was not exceeded. Thus when the throttle was fully forward (not in the gate position) the opening would increase with decreasing atmospheric pressure until it is fully open (at FTH).

This is explained here: http://www.enginehistory.org/Piston/...erlinABC.shtml

Both positions of the red painted lever are shown in the drawing. I painted red lines into the drawing to show that the lever doesn't obstacle the gate position in any of the two positions.

This graph shows that 12lbs boost would be available below about 15k feet, 2.5k feet below the full throttle altitude of 9lbs boost. That's how it works with outside pressure. And that's what being made possible with the abc cut out, see 41Sqn_Banks link.

The article decribes various systems used on the Merlin in general, not the Merlin XII in the summer of 1940, which the question at hand.

You have just posted the August 1940 manual of the Spitfire II, what engine limitations does it show? It would settle the matter quickly, wheter there was any change compared to the June/July manual, which clearly states +9 lbs for all out.

After all, this is what its all about. The fact alone that there's a boost control cutout doesn't give a single idea about the permissable boost, which as noted was set as +9 in the earlier manual. We need to know if this was changed or not.

It may well be a simple emergency override for manual boost control, as was its original function, i.e. a the pilot manually controlling boost depending on altitude, which may well allow him to overboost and damage the engine.

Hmm, you are probably right, at first the little notch seemed to be getting into the throttle's way, and it would be logical, given its location, but come to think of it, the notch is probably just to set the angle of the red lever itself against the t. quadrons when its not engaged.

IF the ABC cutout was set to maintain +12 lbs boost and not +9, that is. Currently it seems as per the July 1940 manual that the ABC cotout was maintain +9 lbs boost. But as the evidence stands, the ABC cutout was unlikely to have been modified until 1941, when +12 was cleared for 5-min all out level.

Yes theoretically its possible for the supercharger to maintain that boost, but certainly not with the gate control.

The notes posted by Kwiatek show that for the later 100 octane planes where use of 12min for 5min instead of 3min was allowed the effectiveness of the boost is up to 10.5 kfeet

To my understanding one could go to 9 lbs without physical restriction on the throttle but had to push through the override (applying a small extra force?) in order to go to 12 lbs. Once engaged there was no more indication to the pilot through "feel" if the throttle was at 9 lbs or 9.5 lbs. Of course he would have to be carefull when using 9 lbs also.

I just checked the the Spitfire II Pilot's Notes and it clearly mentions the "Boost cut-out EMERGENCY control", note that the page is not amended and shows the June 1940 content:

http://forum.1cpublishing.eu/attachm...1&d=1336912226

Please show the evidence for a single Merlin engine ever being fielded with a boost control cutout modified for 9lbs boost. I may then consider this hypothesis of yours for an argument.

But IF we were talking hypotheticals, it's still totally absurd to assume that the boost control cut out has no effect if used under full throttle conditions. What a bunch of idiots the engineers must have been.

Curious to see evidence.

You do have evidence for the clearance of +12 boost for 5 minute "all out" in 1941? This would obviously close the case.

The 'little thing' above the Push sign is the actuator for the 'throttle closed warning' horn switch. Look closely.

Also examine the boost page that you yourself published here
http://forum.1cpublishing.eu/showpos...9&postcount=66

It says COMBAT 5 MINS LIMIT. 3,000 rpm +12lbs

The Merlin XII was able to use constant boost pressure of up to +12 psi using 100 octane fuel

With +12lbs available it would have been used whenever the pilot felt he needed it. There was no air ministry beaurocrat sitting in the cockpit to slap his wrist. Engine life/wear may have been a consideration but the Merlin XII was built nore strongly than the Merlin III for just that reason.

This has been hammered out again and again and you constantly come back with red herrings. Give it up.

Is it possible, that the June/July manual was written for 87 octane?

Exactly correct as I understand it from data posted in previous thread:

http://forum.1cpublishing.eu/showthread.php?t=29031

One thing about the Spit II throttle quadrant diagram posted by Banks in this thread is that it does not include the cable attached to the red tab going to the boost control cutout, without the cable it is easier to confuse it for some type of physical barrier (as the CloD devs did).

The Spit II is rather confusing with two separate systems (gate take off boost and boost override), especially as they give approx the same boost (+12psi) in quite different ways, from controls (throttle gate; red tab) that are about an inch away from each other. I think CloD should probably not model the take off boost system anyway, it is not really relevant for combat.

It also creates confusion that +9psi is the normal full throttle boost for the II (as +6 1/4 psi is for the Spit I), and does not require the boost override (which gives +12psi). CloD gets this rather wrong by modelling Spit II boost behaviour like a +6 1/4 psi Spit I with +9psi instead of +12 psi after boost override. On the bright side, the (post patch) Spit II sea level speed at +9psi is about right (even though the boost is acheived incorrectly), and the 109s are (unhistorically) slow enough to compensate for the lack of +12psi and give a most fun 109/Spit II matchup (at around 30kmh too slow for both :)).

camber

The Merlin was always equipped with an automatic boost control which prevented the engine being overboosted ie; with 100 Octane fuel it was potentially capable of reaching +17 lbs boost but the ABC limited it to +12 lbs for the Merlin II and III

http://i91.photobucket.com/albums/k3...it1-12lbs3.jpg

I do get a little bored with these constant snipes at what I have and haven't disclosed without anything to support them.

I repeat (for I think the third) time, you can always ask for a copy and prove me wrong. On the other hand if Pips had found the papers I found he wouldn't have made his claim.

I have asked you to supply any evidence to support any one (note not all) of the claims he made. For example the May meeting of the War Cabinet that was supossed to have started the whole thing off by stopping the roll out and the fuel shortage he commented on.

The only person who hasn't provided any evidence, or even a statment on what you believe the position to be is you. You only overstate the importance of one document that I left in to maintain the document trail

Well can we see the contents of AIR documents or not? We have been asking for them for three years, you REFUSE to show the whole document.

That's a fact David.

Its your opinion, not Pips. You certainly like to misrepresent other people's positions.

Dear David, you are pretending again that you have not been answered on that multiple times. I have made it very clear to you that the above is based on the documents Pips has found.

Asking me to provide the papers Pips found in Australia was silly in the first place, pretending I am refusing to supply the papers I have nothing to do with for the umpteenth time is dishonest.

Yada-yada-yada, the usual BS, repeated forever in Goebbels style. I have made my position very clear, several times. It seems redundant to repeat it again, since your standard operational procedure in the past was, and is ever since, to wait a few days and lie again that nothing was provided, not even the position was made clear etc.

All what you have done yourself so far is keep making the same statements, ignore other's position and even your very own papers, and then lie that they have supplied nothing and did not make their position clear. Its a petty attitude.

Nope. All documents Pips and you have found notes that only select converted in May 1940. You simply ignore what is in your own papers.

I have shown everything that I have. I repeat its easy for you to obtain copies of the papers. Find that I have witheld anything of importance (and I will let the mods decide) and I will apologise to one and all and withdraw from the forum. If you repeat these allagations without support then I expect you to apologise and withdraw from the forum.
Call my bluff

Give one example to support this statement?

No one has seen the papers that Pips is supposed to have found, not even you. If it was that easy for him then something would have appeared.Then all you have is Pips unsupported posting.
You have
a) No supporting information that there was s fuel shortage
b) No mention in the Cabinet War papers for May saying that the roll out was halted.

It is by definition an unsupported posting

Then prove my lie (another accusation I note) find where you stated your belief. The only ones that I know of are your statement re the use of 100 Octane in France, and a couple of years ago a statement that you supported Pips view that approx 145 fighters were converted.
If you believe that its the 16 + 2 then say so and I will never ask the question again, ever. But I will ask how you support that view.

Again prove my lie, show me what you have supplied and my very own papers. We have a different view on what certain squadrons means, that I agree but the paper trail I believe supports my view and I ham always happy to stand by it.

You keep making these statements and its time to support them

Glider, (this is a bit of a tangent)
Did you order the papers from the archives at Kew?
I live not far from there and was going to order some docs. Approximately how much do the documents cost?

Pips is a member of this forum and has been contacted here and elsewhere to comment on these papers, but has not done so, so whatever Kurfurst thinks Pips may have found is meaningless hearsay, as are the "papers" themselves, which are so full of flawed logic and nonsense reasoning that they are worthless anyway. As it is Kurfurst cited Pips' "summary" verbatim in the Feature # 174 Report only to have it deleted, so the managers don't consider a summary from an old thread in a locked members only forum to be evidence of anything, nor should anyone else. They might be relevant in Kurfurst's HO but nobody else shares that HO - including Pips.

I don't care for your rubbish. The next time you lie about my or other people's posts or position they have taken, the proper course of action shall be taken. You refuse to disclose the documents in full, end of story.

Also please take note for the future that I have decided not to waste any more time on replying to your posts.

From ANA.

Everyone to the lifeboats.

http://3.bp.blogspot.com/-zzHOHGghea...600/crying.jpg

Proposals to secure sufficient 100 octane supplies.

You may have replied to my posts but you have rarely awnsered any questions or supported your statements.

This is another example of you throwing demeaning comments around and when asked to support, substantiate or provide examples, you run and hide. Sadly I expected nothing less.

I repeat, if you think that I have lied, provide examples that satisfy the Mods who are independent, and I will leave the Forum for good. Its a simple, clear statement I cannot and will not hide from.

Your inability to do this will speak volumes.

PS If Publishing some pre war papers that show that the RAF had plans to equip approx 2,500 front line aircraft with 100 octane around the end of 1940 is the best you can do then I feel secure

Kurfurst, you haven't shown any actual evidence, its that simple.

Lots of pre war documents and personal speculation/spamming/personal attacks, It's tiresome and irrelevant.

http://i91.photobucket.com/albums/k3...arpe/ff3lu.gif

And still he tries to post non evidence in the Bug Report hoping that the mangers will accept a verbatim account of a summary presented on an old, members only thread...

I went to the archives and looked at the files myself. As to the cost I don't know but the Oil Committee file is a big one with hundreds of pages so expect cost to be high. I just copied anything which mentioned 100 Octane, they discussed other things but those I left.

I suggest going yourself its a bit special and you can ask for almost anything. Also some things that cost such as downloads of combat reports to your home are free at the NA. You can take a camera in and photograph what you want so you don't have to copy everything out word for word. The first visit is a bit of a fag as you have to get your pass but its worth the effort.

I admit to getting a buzz out of holding the original documents. When this pips thing came up one of his claims was that the War Cabinet stopped the deployment of 100 Octane in May 1940. I went to the NA and was able to get hold of the original papers, and to just handle these original papers that were at the table with Churchill and the others does make it a bit special.
These are now free on line and the originals stored but its an example.

Its a short walk from Kew underground station and well signposted so thats my choice of getting there

Here's what Oil: A study of war-time policy and administration by D J Payton Smith (HMSO 1971 part of the official war series) says about 100 Octane fuel pre- war plans and the so-called supply problems alluded to by Pips:

http://i91.photobucket.com/albums/k3...9100Octane.jpg

http://i91.photobucket.com/albums/k3...anerevised.jpg

"The pre-war activity had been based on the assumption that United States supplies would be denied to Britain in time of war. In the event, as was shown, they remained available."

"100 Octane came into general use during the Battle of Britain..." confirming the All Commands memo issued on 7 August.

"...there was NO anxiety in these early months of the war about the prospects of supply."

You did vote for it, then proceeded to spam the bug report with nonsense about the power it gives, the usage of it, the damage it causes and the availability of it - all to derail the true position.

OK, I just served a really over the top ban from Alpha so only just got back to this.

Don't hold back, just stop posting.

What the hell do these documents from late 1938 have to do with the BofB?

Can all stop the bashing and the personal attack please?

A.P. 3397 Maintenance (1954)

http://forum.1cpublishing.eu/attachm...1&d=1337715952