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[TomcatViP]

If you set the boost cut-off on it will cool your engine.

Try to use it only when you are on the defensive. It's kinda a cheat.

I expect this to be corrected in the same time they re-installed the more stringent 109's EM rules.

280 is what you shld get with a hurri. Start with a shallow dive and coarse the pitch at 12hr (needle full vertical). Retract your rad to 1/4 to 1/3

With a bit of descent rate you shld get 290 easily. Th's a lot deck even if the 109 will still catch you, you'd get time to think how you can manage the unavoidable fight.

The few time I hve tried the Spit I online I did not have any prob keeping a 109 in gun range. But it might hve changed with patches. I am not the best to make a comment here

[Robo.]

Originally Posted by TomcatViP

If you set the boost cut-off on it will cool your engine.

Try to use it only when you are on the defensive. It's kinda a cheat.

In my experience it's quite the opposite - more heat and more strain with the BCC-O (even though the MFP gain is tiny atm). Can anyone confirm?

[klem]

Originally Posted by Robo,

Hi klem, what do you (except reverse mixture lever axis) consider as a problem with the DH? In my opinion it's not too bad and the RPMs are as expected - once in the air mind you

The control movement for the two-pitch prop went through a mid-stage where the pitch moved (not flipped) from one setting to the other and with slow and careful movement you could actually select a rpm between the two extremes. It would of course alter with changes in power and airspeed so the pilot had to be the rpm 'governor' and adjust it but you could hold a general rpm setting that way. The result was that the general performance of the aircraft, managed that way, was almost as good as the Rotol version but it took some management. I suspect in combat it was shoved to fully fine and left there. Apparently (I've lost the link) it became an officially recommeded method of managing the aircraft for better performance. Unfortunately in CoD it flips between the two. The A2A simulations spitfire models it correctly.

Originally Posted by Robo.

In my experience it's quite the opposite - more heat and more strain with the BCC-O (even though the MFP gain is tiny atm). Can anyone confirm?

I see very little change in the boost with the cutout plug pulled and that is only when I give the prop and/or throttle a little twitch which seems to "wake it up" but that could be my imagination. I do seem to be able to overtake my buddies when its pulled unless our e-states were different so I'm really not sure if its doing anything. There was a long thread about just that point but it didn't come to any amicable conclusion.

I have had engine faiure with the plug pulled for a long time (was it 10 mins + ??) with no overtemp indications.

Actually I'm a bit mystified because we can get the full +6.25lbs on full throttle without the boost override. In the MkI pilot's notes that's the max for take-off, 6.25lbs @ 3000rpm (3 mins max), max climbing +6.25lbs @ 2600 rpm (30mins max), emergency +6.25lbs@ 3000 rpm (5 mins max) max cruising +4.5lbs @ 2600rpm. (The 100 octane combat rating was +12lbs but lets stay on track with 87 octane.)

I wouldnt trust those climbing figures in CoD, I'm sure I've wrecked my engine in less than 30 minutes.

Now this report on the Merlin III
http://www.wwiiaircraftperformance.o...in3-rating.jpg
seems to relate to the 87 octane performance because it has above take-off, climb and cruise figures but there is also a combat power rating of +12lbs. Is this what should be available with the plug pulled? I have found no other sources to indicate this is so but why would it be listed there?

Other bits and pieces suggest an uncontrolled Merlin would overboost to +17lbs and that the 100 octane engine modification was made specifically to keep the MP down to +12lbs so that obviously wasn't occurring on the 87 octane engine which had to be modified for it. In fact I have found nothing to suggest the plug needs to be pulled to get +6.25lbs, no mention of a 'normal' full throttle MP versus plug pulled MP, nor any mention of the plugs use in combat for 87 octane.

The only thing left for me to do is re-read the pilots notes for Section 1 and restudy the cockpit diagrams when I next get back to the library (I noted the above figures from Section 2).

[Robo.]

Originally Posted by klem

The control movement for the two-pitch prop went through a mid-stage where the pitch moved (not flipped) from one setting to the other and with slow and careful movement you could actually select a rpm between the two extremes. It would of course alter with changes in power and airspeed so the pilot had to be the rpm 'governor' and adjust it but you could hold a general rpm setting that way. The result was that the general performance of the aircraft, managed that way, was almost as good as the Rotol version but it took some management. I suspect in combat it was shoved to fully fine and left there. Apparently (I've lost the link) it became an officially recommeded method of managing the aircraft for better performance. Unfortunately in CoD it flips between the two. The A2A simulations spitfire models it correctly.

Hi klem, I am perfectly aware of the propeller developement for early Merlin engines (and happy a2a flyer ), but I believe this was only the case with our Spitfire, not the Hurricane. Although sharing the same engine (Merlin III), the Spitfire Mk.I featuring DH propeller had this 'bicycle pump' prop pitch lever that made finding the RPM sweet spots between full coarse and full fine possible. The Hurricane Mk.I though had slightly different PP controls (lever instead of pump) and it seems the trick was not possible to fiddle with it. At least there is no evidence whatsoever that Hurri could go semi-CSP with a DH airscrew.

That's why I tend to believe that DH props as such are modelled OK for both Spit and Hurri - if you remember, Spit used to be wrong prior to the last patch, they fixed that because we reported this issue and backed it up with evidence (merlin in perspective, Spit Mk.I manuals etc.)

Originally Posted by klem

I see very little change in the boost with the cutout plug pulled and that is only when I give the prop and/or throttle a little twitch which seems to "wake it up" but that could be my imagination. I do seem to be able to overtake my buddies when its pulled unless our e-states were different so I'm really not sure if its doing anything. There was a long thread about just that point but it didn't come to any amicable conclusion.

At this moment, the gain is only 0.02lbs. That is as per data someone pulled out of FM files apparently. It helps a little bit but you will overheat and you can blow your engine quicker than you say 'messerschmitt'.

Originally Posted by klem

I have had engine faiure with the plug pulled for a long time (was it 10 mins + ??) with no overtemp indications.

Confirmed, same here

Originally Posted by klem

Actually I'm a bit mystified because we can get the full +6.25lbs on full throttle without the boost override. In the MkI pilot's notes that's the max for take-off, 6.25lbs @ 3000rpm (3 mins max), max climbing +6.25lbs @ 2600 rpm (30mins max), emergency +6.25lbs@ 3000 rpm (5 mins max) max cruising +4.5lbs @ 2600rpm. (The 100 octane combat rating was +12lbs but lets stay on track with 87 octane.)

Normal full throttle MP was +6.25lbs (that's correct), plug pulled MP was +12lbs - only possible with 100 octane fuel.

The 2600rpm figure is probably on the conservative side even for RL, you can do 2850 with Rotol Hurricane in game with no problem and Merlin could take that in RL, too when necessary.

Full rating for Merlin III with 87 octanes was indeed lower e.g. 4lbs @ 2600rpm for climb ('30) vs. 6.25lbs @ 2600rpm for 100 octane powered one. The 6.25lbs @ 2600rpm combination is mentioned in some sources but that was the early non-CSP variant I suppose as 2600rpm is what you get with DH prop set at fine pitch at optimal climbing speed (called High power climb in manual). The only difference between 87 and 100 octane variants would be Boost, not RPM, obviously

With 100 octanes and BCC-O on, your Merlin III could do 12lbs @3000rpm.

Originally Posted by klem

I wouldnt trust those climbing figures in CoD, I'm sure I've wrecked my engine in less than 30 minutes.

They're fairly realistic and more forgiving from my experience, Hurricane Rotol:

Every machine I get is slightly different regarding overheating characteristics. I would say that the Hurricane is the only machine with some kind of FM variety modelled.

Take off at full power - 6.25lbs and 3000rpm
climb at 6.25 and 2850rpm, rad fully open, watching temps
cruise as desired, usually 4lbs @ fairly low rpm (depending on altitude and water temp)

I never wrecked my engine at 2600rpm full MFP climb (rad open in climb mind you), not even at 2850rpm! I usually climb at 2700-2800rpm

Originally Posted by klem

Now this report on the Merlin III
http://www.wwiiaircraftperformance.o...in3-rating.jpg
seems to relate to the 87 octane performance because it has above take-off, climb and cruise figures but there is also a combat power rating of +12lbs. Is this what should be available with the plug pulled? I have found no other sources to indicate this is so but why would it be listed there?

+12lbs boost was not available at all (impossible) with 87 octane fuel. That chart is almost certain about 100 octane (it's a later version obviously)
Merlin XII was rated at 9lbs @ 2850rpm for climb, just for comparsion.

Originally Posted by klem

Other bits and pieces suggest an uncontrolled Merlin would overboost to +17lbs and that the 100 octane engine modification was made specifically to keep the MP down to +12lbs so that obviously wasn't occurring on the 87 octane engine which had to be modified for it. In fact I have found nothing to suggest the plug needs to be pulled to get +6.25lbs, no mention of a 'normal' full throttle MP versus plug pulled MP, nor any mention of the plugs use in combat for 87 octane.

The plug was there from the day one, but it's function was not WEP (that came in later) but simply what it said - overriding the boost control in case of a failure of the BC. No modification was needed for 100 octane fuel as such afik, the holes drilled were simply to use the existing BCC-O system as emergency power later on. What they did was look we can bypass that thing but we need to limit it to 12lbs because that's about as much as this Merlin can take. So they did. The limit was still 12lbs for either 6.25lbs rated Merlin III or for 9lbs rated Merlin XII (Mk.II Spit).

As you say, no plug needs to be pulled to get the 6.25lbs from Merlin III as that was it's nominal rating.

Normal full throttle MP was 6.25lbs, plug pulled MP was 12lbs - only possible with 100 octane fuel, hope that made sense.

[TomcatViP]

12lb 12lb 12lb... Damn get this out of your mind. Looks like an illness with so much reference.

There is no 12lb until very late in 1940 if ever. The 9lb MkXII shld suffice as an evidence.

Regarding the cruise, Rob I think you are cruising too fast.

At 0 (zero) boost I hve got around 200mph as cruise speed btw 15kft to 20kft and a very cooled engine that let me fight with half rad for nearly all the time full pow is needed in a dogfight.

Usually the 12hour needles is a good ref for WWII fighters both in boost and rpm. But I use 2400 rpm in general

[Robo.]

Originally Posted by TomcatViP

12lb 12lb 12lb... Damn get this out of your mind. Looks like an illness with so much reference.

There is no 12lb until very late in 1940 if ever. The 9lb MkXII shld suffice as an evidence.

You're wrong I am afraid. The early Merlins are well documented and no matter how you look at it, the 12lbs Boost is reality of BoB era. Is there any evidence stating otherwise?

9lbs. Merlin XII was due to improvements over Merlin III + different glykol - hence the +9PSI rating. They both could go 12lbs btw.

Originally Posted by TomcatViP

Regarding the cruise, Rob I think you are cruising too fast.

Matter of opinion or preference I guess, I only mentioned cruise as reference and I state 'as appropriate'. I like higher boosts and moderate RPM - that's 'crusing' in a combat zone called ATAG mind you

[TomcatViP]

Originally Posted by Robo.

You're wrong I am afraid. The early Merlins are well documented and no matter how you look at it, the 12lbs Boost is reality of BoB era. Is there any evidence stating otherwise?

9lbs. Merlin XII was due to improvements over Merlin III + different glykol - hence the +9PSI rating. They both could go 12lbs btw.



Matter of opinion or preference I guess, I only mentioned cruise as reference and I state 'as appropriate'. I like higher boosts and moderate RPM - that's 'crusing' in a combat zone called ATAG mind you

Disagree with you Rob, sry.

I still hve not seen any strong EVIDENCE for the much publicized 100oct and 12lb.
The fact that those guys are pushing the SPit frwrd on that case is also dubious when you think of the Hurri "Big Wings" lobbying that was predominant in the 1940 RAF (just re-read Badder). It does not makes sense to tune up your best competing fighter when you hve 2/3 of your fighter force that struggle everyday and bombers that hve difficulties taking of with war wary equipment field-fitted.

Frankly it looks like more of a Gamer Fantasy.

Regarding the cruise, don't forget that the best manoeuvring speed of teh Hurri is also ard 200mph and not 240

Regarding the boost value for the Spit as it was unvailed breaking the code, just don't forget that the in-game spit hve nearly no drag. Giving her a boost similar to the hurri could hve made her even hair raising than she is for now

[klem]

ggrrrrr, typed this all out once and then hit some keyboard combo that closed the tab

Anyway thanks for the reply.

Originally Posted by Robo.

Hi klem, I am perfectly aware of the propeller developement for early Merlin engines (and happy a2a flyer ), but I believe this was only the case with our Spitfire, not the Hurricane. Although sharing the same engine (Merlin III), the Spitfire Mk.I featuring DH propeller had this 'bicycle pump' prop pitch lever that made finding the RPM sweet spots between full coarse and full fine possible. The Hurricane Mk.I though had slightly different PP controls (lever instead of pump) and it seems the trick was not possible to fiddle with it. At least there is no evidence whatsoever that Hurri could go semi-CSP with a DH airscrew.

I must admit that I assumed the Hurricane lever would allow pitch tuning as I expected the lever to be easier to use than the plunger. I searched the web a loooong time and cannot found mention of it's use in the Hurricane
Anyway my advice to Graveyard Jimmy remains the same, ignore the DH5-20 until you're used to the Rotol then maybe try the more awkward DH5-20.

btw, my Spitfire info came from:
http://www.spitfireperformance.com/spit1vrs109e.html
"The Spitfire I Pilots Notes (A.P.1565A) states:
Airscrew control.- This aeroplane may be fitted with one of the following airscrew controls: (a) de Havilland two position (b) de Havilland constant speed, or (c) Rotol (35°) constant speed. If constant speed control is fitted the r.p.m. can be adjusted to remain as desired, but within the limits allowed by the airscrew pitch range. If the two position control is fitted on this aeroplane it can also be operated to give various airscrew pitch settings between fine and coarse; this is obtained by slowly moving the control between its range of movement until the desired r.p.m. are obtained. For example, if a full power climb is required, instead of pushing the control into fully coarse pitch as the r.p.m. rise after taking-off, the control should be moved slowly forward until the r.p.m. drop to the maximum permissible for climb (2,600) and then pulled slightly back; this will leave the airscrew pitch at the position which gives these r.p.m. until power begins to drop off with altitude. As the power drops off the r.p.m. can be maintained by again fining the airscrew pitch as required. This in effect will give a similar improvement in performance to that obtained by means of a constant speed airscrew. The operation of varying the airscrew pitch in this manner to suit different conditions of flight will be found quite simple after a little experiment."

That's why I tend to believe that DH props as such are modelled OK for both Spit and Hurri - if you remember, Spit used to be wrong prior to the last patch, they fixed that because we reported this issue and backed it up with evidence (merlin in perspective, Spit Mk.I manuals etc.)

The last patch put the Rotol onto the Spifire MkIa, it's not the DH5-20 anymore. The MkI is and is definitely wrong because it 'flips' pitch settings.

At this moment, the gain is only 0.02lbs. That is as per data someone pulled out of FM files apparently. It helps a little bit but you will overheat and you can blow your engine quicker than you say 'messerschmitt'.
........
The plug was there from the day one, but it's function was not WEP (that came in later) but simply what it said - overriding the boost control in case of a failure of the BC. No modification was needed for 100 octane fuel as such afik, the holes drilled were simply to use the existing BCC-O system as emergency power later on. What they did was look we can bypass that thing but we need to limit it to 12lbs because that's about as much as this Merlin can take. So they did. The limit was still 12lbs for either 6.25lbs rated Merlin III or for 9lbs rated Merlin XII (Mk.II Spit).

As you say, no plug needs to be pulled to get the 6.25lbs from Merlin III as that was it's nominal rating.
Normal full throttle MP was 6.25lbs, plug pulled MP was 12lbs - only possible with 100 octane fuel, hope that made sense

Agreed.

Normal full throttle MP was +6.25lbs (that's correct), plug pulled MP was +12lbs - only possible with 100 octane fuel.

The 2600rpm figure is probably on the conservative side even for RL, you can do 2850 with Rotol Hurricane in game with no problem and Merlin could take that in RL, too when necessary.

Full rating for Merlin III with 87 octanes was indeed lower e.g. 4lbs @ 2600rpm for climb ('30) vs. 6.25lbs @ 2600rpm for 100 octane powered one. The 6.25lbs @ 2600rpm combination is mentioned in some sources but that was the early non-CSP variant I suppose as 2600rpm is what you get with DH prop set at fine pitch at optimal climbing speed (called High power climb in manual). The only difference between 87 and 100 octane variants would be Boost, not RPM, obviously

With 100 octanes and BCC-O on, your Merlin III could do 12lbs @3000rpm.

They're fairly realistic and more forgiving from my experience

Hmmm..... not sure on one point. Pilots Notes state +6.25lbs/2600rpm for max climb. 2850 was a combat concession. Admittedly it seems to be written for the Rotol prop as there are a variety of rpms quoted for cruising but I don't know if the boost would have been lower for the DH5-20 in fine pitch (30.25') versus the Rotol (23'). Also, I believe it was still normally +6.25lbs climb for 100 octane on the Merlin III. The 100 octane concessions are stated separately (+12lbs max combat boost and weak mixture running rpm/boosts)

Hurricane Rotol:
Every machine I get is slightly different regarding overheating characteristics. I would say that the Hurricane is the only machine with some kind of FM variety modelled.

Yes we've noticed that. I am wondering if its to do with the early running engine management ("keep cool, stay cool?"). Could they be modelling engine wear? Airspeed also has a lot to do with it, faster=cooler. But it does 'feel' inconsistent.

Take off at full power - 6.25lbs and 3000rpm
climb at 6.25 and 2850rpm, rad fully open, watching temps
cruise as desired, usually 4lbs @ fairly low rpm (depending on altitude and water temp)

I never wrecked my engine at 2600rpm full MFP climb (rad open in climb mind you), not even at 2850rpm! I usually climb at 2700-2800rpm

That's combat concession you're using for climb. Hope you're reporting it to the groundcrew We have often screwed our engines at 2600rpm at max boost in the climb but we would have been pretty slow. +4lbs seems to be on the edge and +3lbs is fine. I think that heating model needs a little bit of tweaking. Can certainly cool it fast by dropping to 2200rpm.

[Quote]
+12lbs boost was not available at all (impossible) with 87 octane fuel. That chart is almost certain about 100 octane (it's a later version obviously)
Merlin XII was rated at 9lbs @ 2850rpm for climb, just for comparsion.
[/Quote[
Agreed, that's probably the answer.

[Robo.]

Originally Posted by klem

ggrrrrr, typed this all out once and then hit some keyboard combo that closed the tab

Anyway thanks for the reply.

Hey klem, I know what you mean, real pita to lose all the text, is it. I almost lost this thread (we're fairly OT I must admit), sorry about the late reply mate.

Good conversation though, I really enjoy this and it's always interesting to read other's guys insights and share the knowledge so to speak.

Originally Posted by klem

The last patch put the Rotol onto the Spifire MkIa, it's not the DH5-20 anymore. The MkI is and is definitely wrong because it 'flips' pitch settings.

Ah I see.

Originally Posted by klem

Hmmm..... not sure on one point. Pilots Notes state +6.25lbs/2600rpm for max climb. 2850 was a combat concession. Admittedly it seems to be written for the Rotol prop as there are a variety of rpms quoted for cruising but I don't know if the boost would have been lower for the DH5-20 in fine pitch (30.25') versus the Rotol (23'). Also, I believe it was still normally +6.25lbs climb for 100 octane on the Merlin III. The 100 octane concessions are stated separately (+12lbs max combat boost and weak mixture running rpm/boosts)

You're right here with 2600 for Merlin III, klem. I checked the manual again. I must admit I am doing 2850 in game whenever possible (don't tell my ackack ), especially when I get involved in a melee right after taking off. Sorry about the confusion, my memory si crap. Obviously, you've been correct in advising this new chap flying her by the book. I'd say later on when he gets used to the CEM, he can certainly squeeze more power in some situations.

Originally Posted by klem

Yes we've noticed that. I am wondering if its to do with the early running engine management ("keep cool, stay cool?"). Could they be modelling engine wear? Airspeed also has a lot to do with it, faster=cooler. But it does 'feel' inconsistent.

I don't think it's that because Spitfire is not doing that - it seem sto be far more consistent. I'd say they really modelled the Hurri with a bit of variety, which feels great in game and I really hope they will model this in some extent for all planes.

Originally Posted by klem

We have often screwed our engines at 2600rpm at max boost in the climb but we would have been pretty slow. +4lbs seems to be on the edge and +3lbs is fine. I think that heating model needs a little bit of tweaking. Can certainly cool it fast by dropping to 2200rpm.

This is what I don't get mate - never happened to me tbh. 2600 is very low. What is you red settings and what is your IAS?

Sorry about the OT guys.

[ramstein]

There is definitely something wrong with the model, now it will blow a gasket after a while of flying conservatively.. the boost is way too fast to overboost..

not sure if the prop is the cause, but something is wrong.. with the Rotol

IMHO

Originally Posted by Robo.

Hey klem, I know what you mean, real pita to lose all the text, is it. I almost lost this thread (we're fairly OT I must admit), sorry about the late reply mate.

Good conversation though, I really enjoy this and it's always interesting to read other's guys insights and share the knowledge so to speak.



Ah I see.



You're right here with 2600 for Merlin III, klem. I checked the manual again. I must admit I am doing 2850 in game whenever possible (don't tell my ackack ), especially when I get involved in a melee right after taking off. Sorry about the confusion, my memory si crap. Obviously, you've been correct in advising this new chap flying her by the book. I'd say later on when he gets used to the CEM, he can certainly squeeze more power in some situations.



I don't think it's that because Spitfire is not doing that - it seem sto be far more consistent. I'd say they really modelled the Hurri with a bit of variety, which feels great in game and I really hope they will model this in some extent for all planes.



This is what I don't get mate - never happened to me tbh. 2600 is very low. What is you red settings and what is your IAS?

Sorry about the OT guys.