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[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 GraveyardJimmy

Thanks! Just to clarify- I move the prop pitch lever rather than the throttle to adjust rpm?

Mixture should remain the same generally?

Edit: Just went up for a flight (cross country quick mission), that worked great, thanks! The other hurricane is a bit easier to keep the RPM at a nice level and the engine shakes a lot less (only on start up now, rather than in flight).

With this hurricane, mixture is full back = rich? When would I use it pushed forwards, other than a little bit at takeoff- at high altitudes where air is thinner so less fuel is needed?

Yes you move the Prop lever to control the prop rpm but at low boost it will fall away anyway.

Leave Mixture on Rich (lever back). It could be leaned (lever forward) for economic cruising wih restrictions on boost/rpm but lets face it, you're not going to be doing that unless you enter into a 2.5 hour patrol scenario By the way if you fly the Spitfire as modelled at the moment the lever is the wrong way round - forward is rich. Should be fixed sometime.

You can play with the mixture, leaning it gradually until the yellow exhaust flame just turns blue but then you are on the edge for those particular circumstances (boost etc) so I don't bother. We're never up long enough to run out of fuel and we can keep the engines reasonably cool by boost and rpm. Focus more on basic tactics like being above the bandit rather than below him and get out before you lose the advantage - ahem.... do as I say not as I do!

I'm only trying to give an operating guide, I'm not trying to give you the perfect setup for various conditions. You could research those in the Pilots Notes and see if the modelling is perfect or not but frankly those are test scenarios. Some guys worry about things like "the flight model delivers 8mph below the XXXXX test data". Well, all a/c were different anyway with no guarantee of returning that test performance and its unlikley you'll be in a perfect "test" situation when you spot that bandit. And as a newbie to the Squadron do you think they'll give you the factory fresh aeroplane? No, the boss gets that one, yours is the one with the near-expired engine

[TomcatViP]

Originally Posted by klem

And as a newbie to the Squadron do you think they'll give you the factory fresh aeroplane? No, the boss gets that one, yours is the one with the near-expired engine

in fact on many occasion that was just the opposite.

[Osprey]

@cheese, I use lower RPM than most, usually plodding about on 2000. It's all tactical anyway, just plain don't need that top speed because I catch Hun in the right place. If you are going flat out they've already seen you.

[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).

[klem]

Originally Posted by klem :
And as a newbie to the Squadron do you think they'll give you the factory fresh aeroplane? No, the boss gets that one, yours is the one with the near-expired engine

Just kidding him, the point is that we all hang our hats on the perfect 'test performance' aircraft but in RL there were variations between aircraft depending on hours flown, past damage etc.

[JG52Krupi]

Originally Posted by klem

Just kidding him, the point is that we all hang our hats on the perfect 'test performance' aircraft but in RL there were variations between aircraft depending on hours flown, past damage etc.

+1 over than speed I stay away from the FM talk, there are just too many variables and "experts" to ever make me want to openly discuss them.

The way I see it is regardless of what you fly its down to who sees who first.

Just wish I could follow my own advice and not plough head long into a fight regardless of who has the advantage

[jimbop]

Originally Posted by JG52Krupi

Just wish I could follow my own advice and not plough head long into a fight regardless of who has the advantage

Lol, exactly my problem, too. Optimism always triumphs over common sense!

[MoGas]

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?

No, I dont have seen seen that ones, if I use Boost Cut Out, she gets more temp.

[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.