wep on RAF planes awol???? boost levels??? no 100 octane fuel:(

[fruitbat]

Spitfire mkI, can't seem to activate wep (push through the gate), 6 1/4lbs max.

Spitfire mkIa same.

Spitfire mkIIa can use wep (push through the gate) goes up to 8lbs boost.

both Hurris, 6 1/4lbs boost max, no wep.

take it theres no 100 octane fuel for the raf since these are the 87 octane boost levels:(

somebody tell me i'm doing something wrong please.

[JG52Uther]

I think you should carry on just as you are mein junge...;)

[fruitbat]

i guess you do, lol.

seriously though, major face palm.....

[Biggs]

To add to this... the Spitfire mkIa has a bugged Prop pitch...

it shares the same Rotol constant speed unit but acts like the deHaviland 2-pitch... it only goes full fine-full coarse...:(

it SHOULD act the same as the mkIIa.

whats the deal Maddox Games... you trying to trick us?;)

this is definitely a bug.. the mkIs started getting fitted with Rotol constant speed propellers in July of 1940.

[fruitbat]

no BF109E1/E4 for Luft, no 100 octane fuel for RAF.

its Battle of Britain, but not as we know it, at least according to history.

100 octane fuel went to the front line units from spring 1940....

[Hunin]

100 octane fuel went to the front line units from spring 1940....

http://www.german-navy.de/pics/postcards/u-boot_typii_001.jpg
:-P

In all honesty though I'm as confused about the content choices made as you are.
I wonder what new content they plan to bring to the playing field once the performance patches are out of the way.

100 octane fuel should be relatively easy to do; a proper E4 would need 3D work.

@ Biggs
What does the other Mk I have?
Maybe the plan was to give one fixed pitch, one two pitch and one CSP?

[Moggy]

no BF109E1/E4 for Luft, no 100 octane fuel for RAF.

its Battle of Britain, but not as we know it, at least according to history.

100 octane fuel went to the front line units from spring 1940....

Actually, I did some research on the 12lb boost Hurricane back last year for my squadron and the question of the 100 octane fuel arose. Here's Britain's stockpile of 100 octane fuel and my comments about it...

31st March 1940: 220,000 tons
11th July 1940: 343,000 tons
10th October 1940: 424,000 tons

"Now the stock levels are interesting and you can read them in a number of ways. You can say either that Britain and it's squadrons were well equipped with the fuel or you could say that Britain was well equipped but held back the fuel.
The way I see it is that those squadrons operating in France and 11 Group would of been well stocked with 100 octane fuel. Those that were in 13 Group would of been less so."

[Hunin]

Thanks for the info m8.

To me the question wether or not to include 100 octane fuel isn't up for debate at all.
If it was there let it be reflected in the sim.
Same goes for 601 N variants or even a F-0 to play around with.
Gameplay balance is a server admin task in my eyes.

[fruitbat]

i can readily find some pilot sources from frontline squadrons, from a varity of books....

I read it the same way as you moggy, except the france part. over france at Dunkirk yes, not hurris based in france.

EDIT agree 100% hunin.

personally would love to see a E1...

[Moggy]

We were debating which Hurricane to use during the latter part of our BoF campaign. We were using the Hurricane fixed pitch and considered used the vanilla "1938" Hurricane. I successfully argued for the inclusion of the 12lb Hurricane. This was my post over on the Tangmere Pilots forum;

As most of you know, I've requested that the Hurricane Mk.I 12lb boost be included at some point (the sooner the better imho) during our BoF campaign. Bunny raised a couple of interesting questions about the aircraft; when was it in service and did they use them during the Battle of France campaign? I've done some research on the aircraft this morning but I'll clarify the differences between the 3 Hurricanes.

Hurricane Mk.I early, 1938: 2 blade Watts fixed pitch prop, no boost
Hurricane Mk.I, 1938: 3 blade Rotol constant speed prop, 6¼ lb boost
Hurricane Mk.I 12 lbs, 1940: 3 blade Rotol constant speed prop, 12 lb boost

The 12lb Hurri's were being tested late in 1939 and were in squadron service by February 1940.
http://www.wwiiaircraftperformance.org/hurricane/151-orb-16feb40.jpg

From what I've read the 6¼ lb'ers could be modified by the squadrons themselves to give a maximum boost rating of 12 lbs.
http://www.wwiiaircraftperformance.org/ap1590b.jpg

The 1st combat reports of a 12 lb boost being used in France are from 18th May 1940 with F/Lt I. R. Gleed of 87 Squadron (based in Lille) and S/L E. M. Donaldson and P/O John Bushell both of 151 Squadron (based in Vitry).
http://www.wwiiaircraftperformance.org/hurricane/87-gleed-18may40.jpg
http://www.wwiiaircraftperformance.org/hurricane/bushell.html
http://www.wwiiaircraftperformance.org/hurricane/donaldson-151sqdn-18may40.pdf

[fruitbat]

didn't know about the hurris in France, thanks:cool:

[Moggy]

Neither did I! I like the fact the 12lb boost was a field modification that squadrons could undertake themselves. If memory serves, it could be done in the space of a morning (might be getting confused with a Sopwith Camel though...don't ask!).

[Flying Pencil]

The way I see it is that those squadrons operating in France

Sure it was not Belgium?

Lille and I think Vitry is in Belgium.

[Biggs]

something seems off... I can climb in a mkIIa @2k ft/min on 4lb boost with my prop set at 2500rpm with a speed of ~230 IAS....

If I take the mkIa (with its bugged prop) and try a climb angle of 2k ft/min with my boost set at 4 and my prop set at coarse making the revs about 2300/2400 rpm i can only manage about 180 IAS.... and thats only for a short peroid of time.. after a few thousand feet ur boost drops to 0 and u cant maintain the 2k climb angle...u can barely maintain 1k!

and also with the mkIa at 18k feet with the boost at 4lb and the prop set at coarse I only manage to hit 240 IAS thats hardly 200 MPH TAS!

how is it possible to reach the planes actual top speed (which is 350 mph IIRC)?

[Hunin]

I can assure you 240 IAS at 18k is not hardly 200 TAS.
More like 325 using the common 2% rule.

EDIT
Easy rule of thumb is "deviation is about 2% each 1000 ft".
In this case: 18*2=36, 240/30=8, 240+80= . . . you get the idea.

EDIT2
Or use bombsight table 2 lol
Probably more convenient.

[Moggy]

If I were doing 240 MPH IAS at 18,000 ft, I'd be pretty happy as I'd be tootling along at 330 MPH TAS. That's according to Bombsight Table 2.

P.S. Flying Pencil, they're both in France (Lille is very close to the Belgian border) and yes...I had to check on google maps!

[Osprey]

Given the 1C have handed out Spitfire pilot notes books with the collectors edition I imagine that they will have to match whatever settings are in the book.

Boost drops off with altitude so you have to apply more power as you ascend, did you do that??

[Biggs]

If I were doing 240 MPH IAS at 18,000 ft, I'd be pretty happy as I'd be tootling along at 330 MPH TAS. That's according to Bombsight Table 2.


my mistake i was reading the CoD manual wrong... the manual says 225IAS @ 18k is 296TAS... After trying it again Im just hitting 220IAS which would make it more like 290-ish TAS

either way its not what the aircraft should be doing at that alt!.. at spit mkI with a MerlinIII engine with a 2-pitch prop should be doing at least 350 TAS at 18K

this is way off.

[Biggs]

Now the mkIIa seems spot on...

@18k on full WEP boost (only managed 4lbs at that alt) with the prop at about 2850 revs I was able to hit the 280IAS mark (354TAS) which is what it should be!

the mkI's seem to be off...I'm not sure about their climb rates being off yet but the top speeds are DEFINITELY off.

In summation: mkIa's prop is bugged , there is no added boost when WEP is applied and it wont hit its top speed at alt (18k ft)

[fruitbat]

good work Biggs:)

[Biggs]

good work Biggs:)

just did another test with the mkIIa and they show (compared against the tests from SpitfirePerformace) that the mkIIa seems to be pretty much spot on for climb rate and top speed. (this plane really is fun to fly)

its the mkI thats off for some reason.

the other thing i noticed is that u cant fly the mkII in anything other than the black and white undersides... which is pretty ironic as is was the EARLIER mkIs that flew in that paint scheme...completely minor issue i know :-P

LUTHIER lets get this mkI issue sorted please!

[fruitbat]

yep, the day/night scheme was changed between end of Dunkirk and beginning of the BoB, sometime in early June.

for the record The Spitfire Story, by Alfred Price lists the diff between 87 octane fuel and 100 as

"giving no improvement at or above 16,500 foot full throttle height of the merlin II and III engines fitted to the spitfires, below that altitude the maximum boost pressure could be raised from 6 1/4 pounds to 12 pounds without causing detonation in the cylinders; the resultant extra power increased the maximum speed by a useful 25mph at sea level and 34mph at 10,000 feet"

and being supplied to frontline squadrons from spring 1940.

[Biggs]

ABSOLUTE BONKERS!!!!!

the mkI is BETTER than the mkIa.... i did this twice cause i didnt believe it the first time...

at 18k WEP boost (4lb) coarse pitch.... i can hit ~260 IAS thats what...340TAS?


at the SAME at SAME boost and pitch... i can only hit 220 ISA in the mkIa

260IAS is still 20mph too slow but its a whopping 40 faster than the 'a' version (which should be the SAME as the mkI in terms of top speed)

:confused::confused::confused:

Edit: i even think the climb rate is better for the mkI vs mkIa but im not sure

[Biggs]

bump... Has anyone else tried this yet? I want to make sure its not just me and my bad flying skills. :-P

[fruitbat]

trying it now:grin:

[*Buzzsaw*]

Salute

Both the Spitfire I and Hurricane I were cleared to use +12 boost with 100 octane fuel on March 20th 1940. By that point, 100 octane fuel was in supply.

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

There are numerous log entries from RAF Squadrons listing the dates the Squadrons converted as well as many histories mention this and there are many photos of aircraft with the '100' markings, for only 100 octane fuel.

http://www.spitfireperformance.com/no611-100oct.jpg
http://www.spitfireperformance.com/no74-100oct.jpg
http://www.spitfireperformance.com/602-16feb40-100octane.jpg
http://www.wwiiaircraftperformance.org/hurricane/151-orb-16feb40.jpg
http://www.spitfireperformance.com/603-ross-pg125.jpg
http://www.spitfireperformance.com/rolls-royce-100oct.jpg
http://www.spitfireperformance.com/price-pg74.jpg
http://www.wwiiaircraftperformance.org/100-octane/1940-0897.jpg
http://www.wwiiaircraftperformance.org/100-octane/Flight_March28_1940_Fighter_Station.pdf
http://www.wwiiaircraftperformance.org/100-octane/banks-fuel.pdf
http://www.wwiiaircraftperformance.org/100-octane/Page_16_from_AIAA-42363-319.jpg
http://www.wwiiaircraftperformance.org/100-octane/aircraft-lubricants-pg12.jpg
http://www.spitfireperformance.com/609sqdn-100oct-training-film.pdf
http://www.spitfireperformance.com/602sqdn-spitfire1-100octane.jpg
http://www.wwiiaircraftperformance.org/100-octane/mckinstry-pg87.jpg
http://www.wwiiaircraftperformance.org/100-octane/mckinstry-pg191.jpg
http://www.wwiiaircraftperformance.org/100-octane/sarkar-spitfire.pdf

There were no shortages of 100 octane fuel:

Wood and Dempster wrote in their book "The Narrow Margin":

As it turned out, aviation spirit was to prove no worry for the R.A.F. By July 11th, 1940, the day after the Battle of Britain opened, stocks of 100 octane petrol used in the Merlin engine stood at 343,000 tons. On October 10th, twenty-one days before the battle closed, and after 22,000 tons had been issued, stocks had risen to 424,000 tons. With other grades of aviation spirit total stock available on October 10th, 1940, was 666,000 tons. Oil reserves were 34,000 tons.

All this information is courtesy of Mike Williams Spitfire site:

http://www.spitfireperformance.com/spit1vrs109e.html

Most of the benefit of 100 octane fuel in the Hurri I and Spit I was at lower altitudes, there was no gain above the rated alt of these planes. Only when the Spit II appeared with a higher boost supercharger at high alt, was there any gain up high.

[fruitbat]

Thanks for all the info Buzzsaw:cool:

[Osprey]

Spitfire: The History

According to RAE trials 12lbs boost would reduce engine life to 10 hours at 3000rpm ground level.

Following trials of 95 and 100 fuel, the decision to supply 100 Octane fuel was made on 16 March 1939. 16 fighter and 2 bomber squadrons were supplied by September 1939

Merlin II produced 1030hp @ 16250ft (42.6" MP) and 1160hp @9000ft (54.3" MP)

Trying to find some performance figures from the Supermarine trials.

[Osprey]

OK, Handling trials held for gun configuration, Martlesham Heath 20th July 1939

K9787 (8 brownings)
Merlin II, 2 blade wood fixed:
time to 20kft = 9.4min
Speed@18.5kft = 363 mph
CEILING = 31,900

K9783 (8 brownings)
Merlin II, 3 blade DH 2 pitch (5/20 bracket):
time to 20kft = 11.4min
Speed@18.5kft = 367 mph
CEILING = 34,400

L1007 (2 hispano, no brownings at all)
Merlin III, 3 blade DH type 5/21 bracket (that is not a CPS unit, it's a later 2 speed bracket for the Merlin III):
time to 20kft = 10.7min
Speed@18.5kft = 364 mph
CEILING = 34,500


So, there's not a massive difference between the types. The difference is in take off distance, acceleration and pilot workload. All spitfires were converted to the 5/29 and 5/30 brackets for CPS during June and July 1940

[Biggs]

OK, Handling trials held for gun configuration, Martlesham Heath 20th July 1939

K9787 (8 brownings)
Merlin II, 2 blade wood fixed:
time to 20kft = 9.4min
Speed@18.5kft = 363 mph
CEILING = 31,900

K9783 (8 brownings)
Merlin II, 3 blade DH 2 pitch:
time to 20kft = 11.4min
Speed@18.5kft = 367 mph
CEILING = 34,400

L1007 (2 hispano, no brownings at all)
Merlin III, 3 blade DH type 5/21 bracket (that is not CPS!):
time to 20kft = 10.7min
Speed@18.5kft = 364 mph
CEILING = 34,500

yep... well the mkIs in this game dont really come close to that.. i got 260IAS @18ooo with the mkI... but thats still about 20 IAS off.

def needs MOAR BOOST!!!!

[fruitbat]

hey Biggs, can you confirm something for me re fuel mix in the spit.

it seems to only have 2 positions correct?

i can't get it to run smooth at 18,500ft guessing its pilot error on my part, any clues?????

also, de Havilland vs Rotol, both on 87 octane fuel, appendix B and C.

http://i7.photobucket.com/albums/y290/thefruitbat1/File0017.jpg

http://i7.photobucket.com/albums/y290/thefruitbat1/File0018.jpg

[Biggs]

Yeah its either full rich or full lean.

[fruitbat]

thats what i thought.

now, why can i not get it to run smooth on either at 18,000ft, any idea what i'm doing wrong?

[madFinn]

Are you applying the pitot probe position errors to get CAS vs IAS? The charts for the Mark 2 are on page 20 of http://www.zenoswarbirdvideos.com/Images/spit/Spit2Manual.pdf

Could be the source of your perceived lack of performance.

[Biggs]

Are you applying the pitot probe position errors to get CAS vs IAS? The charts for the Mark 2 are on page 20 of http://www.zenoswarbirdvideos.com/Images/spit/Spit2Manual.pdf

Could be the source of your perceived lack of performance.

Not sure, but that wouldnt explain why the mkI and mkIa have different top speeds.

The funny thing is the mkI with the 2 pitch should top out a little fast than the mkIIa... MkI should be 364TAS whereas the mkIIa should only make 354...

The main advantage of the mkii is the added hp and constant speed unit. But they only add in climb rate and not top speed

As of right now:
spit mkI - 260 IAS
spit mkIa - 220 IAS
spit mkIIa - 280 IAS

they should all be at least 280 IAS :(

[Sternjaeger]

...omg are you already going so anal?!?! Why don't you lucky sods enjoy what you have and which some of us still can't play instead of wasting time looking for all these data?! :rolleyes:

[Faustnik]

...omg are you already going so anal?!?! Why don't you lucky sods enjoy what you have and which some of us still can't play instead of wasting time looking for all these data?! :rolleyes:

I love the tecnical info. :grin:

http://www.spitfireperformance.com :cool:

[BadAim]

You guys are nuts! Have fun crunching the numbers though, if that's what floats yer skiff.

[fruitbat]

either way, all the RAF planes performance is down on what it should be below 16,500ft.

where's the 100 octane fuel....

[IvanK]

Incorrect Boost indications and Boost Cut out mechanisation was been brought up before release. The developers are aware of it.

[Biggs]

You guys are nuts! Have fun crunching the numbers though, if that's what floats yer skiff.

are u kidding me? I've logged about 14 hours now! (so Steam tells me) I LOVE this game..err sim... the spit is a joy to fly... alot of it is very "real" feeling...

its exactly like the pilots say "hurri is a much more stable gun platform" and the spits controls are "telepathic"...

believe me Im having a WONDERFUL time! :grin:

[fruitbat]

Incorrect Boost indications and Boost Cut out mechanisation was been brought up before release. The developers are aware of it.

thats great to hear, thanks for posting:cool:

[Al Schlageter]

...omg are you already going so anal?!?! Why don't you lucky sods enjoy what you have and which some of us still can't play instead of wasting time looking for all these data?! :rolleyes:

Because OM states that his game is as close to perfection as real life as can be. The lack of 100 octane fuel is a major fubar.

[Al Schlageter]

On 100 octane fuel.

http://www.ww2aircraft.net/forum/technical/use-100-octane-fuel-raf-during-bob-16305.html
http://www.ww2aircraft.net/forum/aviation/use-100-octane-fuel-raf-pt-2-a-20108.html

Glider put a lot of work into this and is the best I have seen on 100 octane fuel use during the BoB.

One might have to register to see the images.

[Biggs]

Incorrect Boost indications and Boost Cut out mechanisation was been brought up before release. The developers are aware of it.

Are they aware of the incorrect top speed of thr mkI models?

[2GFlea]

I saw this command in another thread...

186 = thtl_psicutout

I assume that is the Boost Control Cut Out that would allow the pilot to obtain max boost. Is that different from the legacy Il2 WEP command? I'm not sure if that command is bound by default or what it does in game. You see, I'm in North America, so I have to wait for you guys to finish beta...:-)

[IvanK]

The concept of boost Cut out is similar to WEP but different :) Here is a simplifed description of how it works.

Most RAF/Luftwaffe aircraft had Boost controllers (Most US aircraft at this stage didn't). With Boost control engaged (the norm) the pilot selects the required Boost then as he climbs or descends the Boost controller holds the selected Boost constant without any further pilot action required (below Full throttle height FTH)

In a no Boost controller aeroplane the throttle would need to be progressively opened as you climb until you get to Full throttle height (FTH).

The second function of the boost controller is to limit or "Boost protect" the engine to a rated limit. So the pilot can select Full throttle knowing he is not going to "overboost" the engine. If not equipped with a Boost controller then the additional pilot workload is required to ensure that Boost limits are not excedded.

Boost cutout simply resets the Boost controller limit to some other value above normal rated Boost. In the case of the Spitfires Rated Boost for the MKI, 1A was +6.25Lbs, with MKII at +9lbs. In all cases once Boost Cutout is selected (in the case of the Spits pushing the red boost cut out lever forward and selecting full throttle) will give you +12Lbs boost up to the respective FTH (about from memory 10,500Feet). If desired the pilot could then rotate the Boost cut out switch back (cant do this at the moment in COD on the Spit .. it should be a toggle control). Once done the Boost controller is back using its normal +6.25/+9Lb limit. In the case of the Hurricane the Boost Cut out was a plunger arrangement which works correctly as a toggle in COD. However no change in Boost is evident on the boost gauge.

Its also worth pointing out that at the time of BOB most Boost gauges didn't go up to +12Lbs so Boost cut out (Below FTH) would result in Full scale Boost deflection.

Running at +12lbs brings with it additional cooling and engine wear problems.

As others have stated +12Lbs Boost was only possible if 100 Octane fuel was being used. Its fair enough to state that all operational RAF fighters were running 100 octane fuel during the battle.

So this area needs to be tweaked.

[Biggs]

So yor saying that normal full throttle boost in thr mkII should be +9lb and +12lb when opening the boost gate? As of rigt now its only +9lb AFTER opening the boost gate....

Also what is the point of the mkIa in this sim? I cant quite figure it out... If the prop pitch in the mkIa isnt a bug then what makes it any different from the mkI (besides the fact that it has a slower top speed)?

Are the devs aware that the propellers and nose cone of the mkIa in game are those of the Rotol CSP unit?

[IvanK]

"So yor saying that normal full throttle boost in the mkII should be +9lb and +12lb when opening the boost gate? As of rigt now its only +9lb AFTER opening the boost gate...."

Exactly, correct terminology is selecting Boost Cut out to allow +12Lbs.

http://img842.imageshack.us/img842/9174/spitiialimits.jpg

I am not sure if the devs are aware of Rotol versus DH spinner and blade profiles from 3D graphics point of view with respect the Spitfire. I will have a look myself and see.

[Moggy]

"So yor saying that normal full throttle boost in the mkII should be +9lb and +12lb when opening the boost gate? As of rigt now its only +9lb AFTER opening the boost gate...."

Exactly, correct terminology is selecting Boost Cut out to allow +12Lbs.


The pilots also had to report if they had pulled the boost plug (commonly referred to as 'pulling the tit') in their combat report after each flight.

[IvanK]

"Pulling" for Hurricanes "Pushing' for Spitfires

[Moggy]

Sorry old chap but we're a Hurribus squadron. :mrgreen:

[Sutts]

Most RAF/Luftwaffe aircraft had Boost controllers (Most US aircraft at this stage didn't). With Boost control engaged (the norm) the pilot selects the required Boost then as he climbs or descends the Boost controller holds the selected Boost constant without any further pilot action required (below Full throttle height FTH)

In a no Boost controller aeroplane the throttle would need to be progressively opened as you climb until you get to Full throttle height (FTH).


Thanks for the explanation IvanK. Is my understanding correct please?.....

The boost controller (limiter) will only hold the boost constant (at rated boost) if a throttle setting is selected which would exceed that rated boost. If I select a lower boost value like 3lbs in a climb, the controller won't feed in more throttle to maintain that value will it?

I think what I'm trying to say is that the controller is only capable of maintaining a boost value by reducing throttle input, not by increasing it.

Does that make sense?

Thanks:grin:

[robtek]

Thanks for the explanation IvanK. Is my understanding correct please?.....

The boost controller (limiter) will only hold the boost constant (at rated boost) if a throttle setting is selected which would exceed that rated boost. If I select a lower boost value like 3lbs in a climb, the controller won't feed in more throttle to maintain that value will it?

I think what I'm trying to say is that the controller is only capable of maintaining a boost value by reducing throttle input, not by increasing it.

Does that make sense?

Thanks:grin:

Afaik the boost controller only controls that the boost doesn't exceed the limits!
It never controls the throttle.

[Sutts]

Afaik the boost controller only controls that the boost doesn't exceed the limits!
It never controls the throttle.

Robtek,

that was my understanding too.

I was referring to IvanK's statement:

"With Boost control engaged (the norm) the pilot selects the required Boost then as he climbs or descends the Boost controller holds the selected Boost constant without any further pilot action required (below Full throttle height FTH)

In a no Boost controller aeroplane the throttle would need to be progressively opened as you climb until you get to Full throttle height (FTH).

[IvanK]

As I understand it the Boost controller does as described. (Happy to be proved wrong though) Lets say we are at 4000ft we select +4lbs of boost with the throttle. So the throttle might be in say the 75% physical position. As we climb the throttle remains physically fixed but the boost controller maintains the boost (By varying the supercharger valves) up to that particular Boost Full throttle height. The Automatic Boost Control (ABC) has 2 functions Overboost protection and Pilot work load alleviation by holding boost constant (within limits) as the pilot climbs or descends.

In say an Allison without a Boost control you do the same say at 4000feet you select +4Lbs Boost (about 23"MAP). You then start to climb unless. If you leave the throttle where it is then MAP/Boost will start to drop so as you climb you need to advance the throttle to maintain your selected boost. In addition an aggressive push ion the throttle could exceed Boost/MAP limits.

If you can get a copy of the RAF manual AP2095 Pilots Notes general it is well described there. Below is a snippet from that manual dealing with the differences between ABC equipped and non ABC equipped aircraft. tHe first paragraph talks about Boost maintenance in the climb

http://img130.imageshack.us/img130/2678/abc1q.jpg

[41Sqn_Banks]

Air Publication 1590B
Volume I, 2nd Edition
October, 1938 (Reprinted October, 1939)

Merlin II and III Aero-Engines

Atomatic Boost Control

General
239. All Merlin III and the majority of Merlin II engines are fitted with a variable datum (or progressive) type of automatic boost control unit. Early Merlin II engines were fitted with the fixed datum type of boost control, but these will eventually be replaced by the variable datum unit.

240. The variable datum automatic boost control prevents the boost pressure from arising above normal boost at all altitudes below and up to rated altitude. It consists of a device which provides a superimposed control over the hand-operated throttle, thereby relieving the pilot of the need for constant observation of the boost gauge to maintain the boost pressure within the limits. With the fixed datum type of automatic boost unit for which the control has been set, maximum permissible boost is obtained soon after the throttle is opened past the slow-running position. In consequence of this, below rated height and particularly near ground level, it is only possible to open the htorttle a small amount with the result that a considerable degree of lost motion in the cockpit throttle operating lever occurs. With the variable datum type of automatic unit the variation in boost pressure is proportional to the throttle opening, so that the lost motion between throttle lever and butterfly valve is eliminated and the movement of the pilot's throttle lever is a definit indiction of the boost pressure obtained; moreover, up to rated altitude, any given position of the pilot's throttle lever will always give the same boost pressure.

[Sutts]

Air Publication 1590B
Volume I, 2nd Edition
October, 1938 (Reprinted October, 1939)

Merlin II and III Aero-Engines

Thanks for enlightening me guys. I've studied a few original Spit manuals and never seen this mentioned for some reason. The evidence is all there though.

Cheers

[Kwiatek]

"So yor saying that normal full throttle boost in the mkII should be +9lb and +12lb when opening the boost gate? As of rigt now its only +9lb AFTER opening the boost gate...."

Exactly, correct terminology is selecting Boost Cut out to allow +12Lbs.

http://img842.imageshack.us/img842/9174/spitiialimits.jpg

I am not sure if the devs are aware of Rotol versus DH spinner and blade profiles from 3D graphics point of view with respect the Spitfire. I will have a look myself and see.

Im not sure if power settings for 100 Octan fuel Merlin III which was used in SPitfire Mark 1 was +6 1/2 lbs ( nominal power ) and +12 lbs ( emergency power). It is possible that Merlin III with 100 octan fuel had different power settings - similar to Merlin XII ( Spitfire Mark II) and Merlin 45 early ( Spitfire Mark V)

Look at these document for Merlin III engine from 1940:

http://i53.tinypic.com/r0p095.jpg

IT doesnt look similar to Merlin XII which used also 100 octan fuel?




Also developers really dont care too much RL performacne of BoB planes ( Spitfire, Hurricane and 109). It is another their fault in these game. I just check COD manual with peformacne data for Spitfire, Hurricane and 109 where is very wrong data for these planes ( climb rate, maximum speeds and turn rate).

Here are some RL data for these planes:


Spitfire Mark I from BOB period ( CS propeller, aditional armour and windshield)

Here is speed with old power settings - +6 1/2 lbs and with new emergency power - + 12 lbs.

http://www.spitfireperformance.com/spitfire-I-rae-12lbs.jpg


Spitfire MK1 climb rate at 6 1/2 lbs:

http://www.spitfireperformance.com/n3171climb.jpg



Spitfire turn rate at 6 1/2 lbs CSP:

http://i51.tinypic.com/2gspoc9.jpg



Hurricane MK1 from BOB peroid ( CS propeller, aditional armour, 100 octan fuel)

http://www.wwiiaircraftperformance.org/hurricane/hurricane-I-level.jpg


Climb rate for Hurricane MK1 but without aditional armour and armoured winshield

http://www.wwiiaircraftperformance.org/hurricane/Hurricane_Climb-HRuch.png

For comparison climb rate at 6 1/2 lbs Hurricane withou armour and with aditional armour

http://www.wwiiaircraftperformance.org/hurricane/hurricane-I-climb-6lb.jpg


And the same with speed - Hurrciane MK1 without aditional armour

http://www.wwiiaircraftperformance.org/hurricane/Hurricane_Speed-HRuch.png

( Hurricane from BOB peroid with aditional armour/ armoured windshield would be slowier)



Bf 109 E-3 with DB 601 Aa engine - 1.45 Ata emergency power:

D a t e n b l a t t Me 109.

A b m e s s u n g e n:

Spannweite 9,90 m

Gesamtlänge 8,76 m

Grösste Höhe 2,45 m

Flügelfläche 16,40 m


G e w i c h t e:

Zelle 650 kg
Triebwerk 1075 "
Ständige Ausrüstung 85 "
Zusätliche Ausrüstung 200 "
Rüstgewicht 2010 kg
Zuladung 530 kg
Fluggewicht 2540 kg


M o t o r l e i s t u n g:

1) Nennleistung 1100 PS in 3700 m Höhe
bei 2400 U/Min.
(5 min. Kurzleistung in 3700 m Höhe)

Erhöhte Dauerleistung 1050 PS in 4100 m Höhe
bei 2400 U/min
(30 Min.)

Dauerleistung 1000 PS in 4500 m Höhe

Sparsame Dauerleistung 970 PS in 3700 m Höhe
Bei 2250 U/Min.

2) Startleistung 1175 PS in 0 m Höhe
(zulässige Dauer 1 Min.)
bei 2500 U/Min.

3) Bodenleistung 1015 PS in 0 m Höhe
Kurzleistung (5 Min. Dauer)
bei 2400 U/Min.

Erhöhte Dauerleistung 950 PS in 0 m Höhe
(zulässige Dauer 30 Min.)
bei 2300 U/Min.

Dauerleistung 860 PS in 0 m Höhe
bei 2200 U/Min.



Speed:

Höchtsgeschwindigeit in 0 m 500 km/h
in 1000 m 510 "
in 2000 m 530 "
in 3000 m 540 "
in 4000 m 555 "
in 5000 m 570 "
in 6000 m 565 km/h
in 7000 m 560 km/h

http://www.kurfurst.org/Performance_tests/109E_Baubeschreibung/109E_Bau_speed.png

Climb rate:

S t e i g z e i t e n.


Steigzeit auf 1000 m 1,0 Minuten
auf 2000 m 1,9 "
auf 3000 m 3,0 "
auf 4000 m 3,8 "
auf 5000 m 4,9 "
auf 6000 m 6,3 "


http://www.kurfurst.org/Performance_tests/109E_Baubeschreibung/109E_Bau_climb.png


Turn rate :

These are, at Sea Level and at 6000 m, with and without deploying flaps to aid turning :

Without use of flaps :
at 0 m altitude - 170 m (557 feet), at 6000 m (19 685 feet) altitude - 320 m (1050 feet).

With use of flaps :
at 0 m altitude - 125 m (410 feet), at 6000 m (19 685 feet) altitude - 230 m (754 feet).


Similiar figures are given by a calculation by Messerschmitt AG on Bf 109E turn times and radius in an internal Messerschmitt report.

The calculation was based on a similiar set of data, but assumes the slightlly lower power output of the DB 601A-1 at 990 PS. Conditions in the calculation were 2540 kg weight, 990 PS output, an altitude of 0 m and no height loss. Under these conditions, the turning characteristics of the Bf 109E were as follows :

Turn time for 360 degrees: 18,92 seconds.
Turn radius for above turn: 203 m

Take note that the smallest turning radius and the best turning time do not occur at the same airspeed, which would

Further calculations were made for a diving turn of a descent rate of -50 m/sec, which would be equivalent translate to an overall power output

Turn time for 360 degrees in a -50m/sec diving turn : 11,5 seconds.
Turn radius for the -50m/sec diving turn above : 190 m



For comparison turn rate for Spitfire MK1, Hurricane MK1, 109 E-4


SPITFIRE Mk.I

Turn Performance
300mph - 1,000ft 5,000ft 10,000ft 15,000ft
One 360 - 12.2s 13.5s 14.7s -
Two 360s - 24.9s 28.2s 30.3s -

250mph
One 360 - 10.8s 12.8s 13.4s 14.1s
Two 360s - 24.4s 28.2s 29.9s 33.2s

Sustained
No Flaps - 14.8s 16.0s 17.8s 20.8s
Full Flaps - 15.1s 16.4s 18.1s 21.8s
Best Flap - none none none none
Speed/best - 125mph 125mph 125mph 120mph


Hawker Hurricane Mk I

Turn Performance
300mph - 1,000ft 5,000ft 10,000ft 15,000ft
One 360 - 12.1s 12.4s 13.6s -
Two 360s - 24.2s 25.3s 30.0s -

250mph
One 360 - 10.2s 11.7s 12.9s 15.0s
Two 360s - 23.6s 26.2s 28.5s 33.2s

Sustained
No Flaps - 14.8s 16.4s 18.5s 22.1s
Full Flaps - 14.8s 16.6s 18.4s 22.2s
Best Flap - full full full full
Speed/best 105mph 105mph 100mph 100mph


Bf-109E-4

Turn Performance
300mph - 1,000ft 5,000ft 10,000ft 15,000ft
One 360 - 12.9s 13.4s 15.4s -
Two 360s - 29.4s 31.2s 35.0s -

250mph
One 360 - 12.9s 13.7s 15.5s 16.7s
Two 360s - 31.0s 32.4s 36.5s 41.2s

Sustained
No Flaps - 18.0s 19.3s 21.2s 24.1s
Full Flaps - 19.0s 19.8s 21.7s 24.8s
Best Flap - none none none none
Speed/best - 120mph 120mph 120mph 115mph





RL Data Speed for comparsion between Sptfire MK1 +12 lbs ( red) - Hurricane MK1 +12 lbs ( green) - 109 E-3 1.45 Ata ( black)


http://i56.tinypic.com/9qcrvb.jpg



And now for comparson data from COD:


http://i1230.photobucket.com/albums/ee494/JZG_Thiem/speed.jpg


http://i1230.photobucket.com/albums/ee494/JZG_Thiem/climb.jpg


http://i1230.photobucket.com/albums/ee494/JZG_Thiem/turn.jpg



COD looks really off here. Development team really didnt make their homework like we should expect.

[Sven]

No kidding Kwiatek, and thanks for that detailed post!