51D and F4U-4

[Karnak]

For the Mossie's Merlin 25s the handbook lists 2,850rpm at +9lbs as the 1 hour limit, 3,000rpm at +18lbs is the 5 minute limit.

It is academic in any case.  I don't think making it take longer to get to the action is a good thing.

The one place I think it might be a good idea to review engine settings is if bombers are getting to use 5 minute limits as continuous settings.

[RTHolmes]

saxman the merlin's "boost" is just the Brit term for manifold pressure, its not like hitting a switch for water injection or NOS. the merlin's 5min 3000/+18lb limit is what you would call a precedural limit, not a physical limit, just like the corsair's 2700/53"

the interesting thing for me is the difference between the the US 30min and Brit 5min limits for 2,700/53" on the corsair. Note the US charts show a 5min limit for 2700/52" on the jug's R-2800-21. I wonder if there are any other examples where the US limits are more generous than the Brit limits for the same aircraft?

also note that although I'm english and fly with a RAF squad whose squad aircraft (or the closest to it) is the Spit VIII, I spend alot more time in the D25 than anything with a merlin engine so any changes here would not work in my favour...

The one place I think it might be a good idea to review engine settings is if bombers are getting to use 5 minute limits as continuous settings.

they certainly are, see: http://bbs.hitechcreations.com/smf/index.php/topic,265122.0.html

[Saxman]

saxman the merlin's "boost" is just the Brit term for manifold pressure, its not like hitting a switch for water injection or NOS. the merlin's 5min 3000/+18lb limit is what you would call a precedural limit, not a physical limit, just like the corsair's 2700/53"

Yes, I realize that "WEP" in the Merlin is merely higher throttle settings. However there are STILL certain settings in the SOP that were specified as being "emergency power" above regular MIL/Combat power (this is where the wire stop on the throttle I believe Widewing has discussed came into play). IE, settings I'm finding for the P-51B:

WEP: 3000/67"
MIL: 3000/61"
Normal: 2700/46"

The P-51 doesn't use injection but merely a higher throttle setting, but they still differentiate between WEP and MIL. So saying that Plane A should be restricted to its max continuous because Plane B can't fly around on WEP indefinitely REALLY sounds absurd.

[RTHolmes]

Spit IX Pilot's Notes:
Combat            3000/+15      5min
Max Take-off      3000/+12      none stated, assume 15min
Max Climbing      2850/+12      1h
Max Continuous    2650/+7       continuous

AH Spit IX:
WEP               3000/+15      5min
MP                2850/+12      continuous
NP                2650/+7       continuous
MC                2400/+4       continuous


P-51B/C Pilot's Notes:
Combat            3000/67"      5min
Max Take-off      3000/61"      15min
Max Climbing      2700/46"      continuous
Max Continuous    2700/46"      continuous

AH P-51B:
WEP               3000/67"      5min
MP                3000/61"      continuous
NP                2700/46"      continuous
MC                2500/43"      continuous


seems this modelling ... err ... discrepancy is more widespread than I thought ...


edit: I'll summarise the charts above.
IRL the P-51B could use 3000/61" for only 15min at a time. In AH it can fly an entire sortie at this setting.
IRL the Spit IX could use 3000/+12 for only 15min at a time. In AH it cannot fly an entire sortie at this setting.

[SgtPappy]

It seems that since the Spitfire cannot use the maximum take-off RPM but can use the maximum throttle boost psi (non-WEP), then all HTC would really have to do is tweak the model so that the maximum RPM is achievable without actually using the WEP boost pressure.

For the other aircraft (seems like the UK ones so far), are there the same strange limitations apparent on BOTH boost and RPM or just RPM like the Spitfire IX example?

If the flaw is the latter, then perhaps the aircraft that suffer from a lack of proper max RPM like the Spitfire can be adjusted so that they can use the higher RPM. Increasing the RPM increases performance less than increasing boost pressure, which is something that Sax would probably like to hear.   

EDIT:
Or maybe HTC can actually put these limitations perfectly in place. Using the F4U as an example, 2550 rpm/49.5" Hg for the F4U's continuous engine settings, 2700 rpm/54" Hg for 5 mins; re-useable after cool-down and 2700 rpm/60" Hg (currently it's 2700 rpm/57.5" Hg); non-reuseable after 5 mins total use.

But I suppose that's wishful thinking.

[Saxman]

It seems that since the Spitfire cannot use the maximum take-off RPM but can use the maximum throttle boost psi (non-WEP), then all HTC would really have to do is tweak the model so that the maximum RPM is achievable without actually using the WEP boost pressure.

For the other aircraft (seems like the UK ones so far), are there the same strange limitations apparent on BOTH boost and RPM or just RPM like the Spitfire IX example?

If the flaw is the latter, then perhaps the aircraft that suffer from a lack of proper max RPM like the Spitfire can be adjusted so that they can use the higher RPM. Increasing the RPM increases performance less than increasing boost pressure, which is something that Sax would probably like to hear.   

EDIT:
Or maybe HTC can actually put these limitations perfectly in place. Using the F4U as an example, 2550 rpm/49.5" Hg for the F4U's continuous engine settings, 2700 rpm/54" Hg for 5 mins; re-useable after cool-down and 2700 rpm/60" Hg (currently it's 2700 rpm/57.5" Hg); non-reuseable after 5 mins total use.

But I suppose that's wishful thinking.

Fixing the RPMs on the Spitfires is a very easy change that doesn't require DRASTICALLY redoing engine management into what you're proposing, which is effectively a two stage WEP. At this point, making ANY sort of change to WEP mechanics is going to require a virtually entirely new engine management system.

[SgtPappy]

Yea, I thought that the '2-stage WEP' was wishful thinking indeed.

However, for example - changing the Spitfire's max continuous RPM to 3000 along with the already stated +12 lb. boost would work too. This way, the performance hasn't really been increased much at all. Also, it will allow the F4U and P-51 to keep their high-RPM/high-boost settings as continuous settings.

No uber-performance in Spits, no nerfed F4U's, and the same engine management as we have now. Everyone's happy.

EDIT: (again)

Oh and Sax, I remember you stating that the birdcage F4U-1 is not supposed to have WEP at all. Does this mean that the F4U-1A's before December 1943 that didn't have water-injection didn't have any sort of WEP either?

Also, did ALL birdcage F4U-1's lack the stall strip on the starboard wing? If this is the case, then the F4U-1 we have will need more tweaking than just WEP adjustment.

[Saxman]

The F4U-1A we have is a late-block version with the paddle prop, so would still have WEP regardless of whether or not HTC removed it from the -1. The problem is because of how the 1/1A differentiation is handled makes a lot of things very confused. Like the US manual doesn't mention the 1A at ALL, (Even though it includes the 1D and 1C) because "1A" was a back-dated designation created later. If the 2700/59" setting was ONLY achieved due to the water-methanol injection, then it should not be present in the -1 birdcage, which was never factory-built with this equipment. This still leaves a question over whether the -1 could reach these settings without injection. Do any of our document gurus have clear, definitive information that can clarify this? I'd say a pilot manual dating from prior to December, 1943 that omits the 59" MP setting would be pretty conclusive.

As far as the stall strip, I'm not sure when Vought added it, and whether it was during the -1 Birdcage production or came after the switch to the bubble top.

[RTHolmes]

I think its pretty clear from both the US and Brit manuals that 2700/53-54" was the max that could be pulled without water injection, and only for a limited time. one of them states that for the 8W this throttle position is about 3/4" short of the microswitch which activates the injection.

[SgtPappy]

Sax,

Concerning the stall strip, I suppose I'll do more research to find that out.

Holmes,

A simple solution is to simply allow the other aircraft like the Spitfire to use higher RPMs (3000 RPM with +12lb boost) as a continuous setting as a continuous setting rather than nerfing both the max RPM and MAP of the F4U to 2550 RPM/49.5" Hg. This way, all the aircraft have their full range of throttle settings.

[RTHolmes]

you could do that, and that would model eg the 51B and IX similarly. have a look at this though:

Spit XVI Pilot's Notes:
Combat            3000/+18      5min
Max Take-off      3000/+18      none stated, assume 15min
Max Climbing      2850/+12      1h
Max Continuous    2650/+7       continuous

model the XVI on the same basis and you effectively get full perma-WEP. However, it still wouldnt be as overmodelled as the F-4U1 currently is though, which already has perma-WEP as the MP setting and a higher 5min WEP setting which wasnt even possible without water injection.

sax and papy I agree when you both implied that the only way to model these settings properly is a 2-stage WEP which may just be a bit too complex for AH. I suspect 80% of the playerbase never even touch the rpm control as it is. the 1-stage WEP we have now is a playability compromise and the power settings modeling is a compromise the suit that. just seems that some aircraft get alot more benefit out of the compromise than others (eg. corsair vs spit), and some are just completely wrong (eg. B-24 vs Lanc).

[SgtPappy]

So perhaps, like you said, our solution would be to lower the Corsair's maximum throttle setting?

I think the reason as to why there is no time limit stated for max take-off is because take-off isn't really going to take a significant amount of time to execute, thereby removing the necessity of implying a time limit on the take-off setting. But looking at all the figures you posted, it is indeed true that the P-51B, F4U's and probably some other planes are using higher MAPs and RPMs versus the Spitfires.

The strange thing is that the US manual states different times for which the F4U can use 2700 RPM/53" Hg. Regardless, I tested the F4U at sea level at ~ 2500 RPM/49" Hg (it's hard to get the extra 50 RPM/0.5") and it turns out that at this setting, the F4U-1A is 3 mph faster than a Spitfire VIII on WEP. Maybe Sax will be slightly comforted by that fact. I know I am!

EDIT: I just can't keep my head from thinking after I finished the post...

It seems that HTC has simply modeled each aircraft's engine based on the absolute max throttle settings. Let's disregard the normal, climb and cruise settngs for now. The absolute max throttle settings for the F4U-1A are 2700 RPM/57.5" Hg in this game. The charts say that the absolute max settings are 2700 RPM/60" Hg. Let's say that setting is equivalent to the 2700 RPM/57.5" Hg we have in-game. The only lower setting is that of the setting without WEP on the charts posted: 2700 RPM/~53-54" Hg. That becomes the maximum military power setting and is continuous.

In the case of the SPit XVI, we have 3000 RPM/+18 lb for absolute max. The take-off happens to be the same. Therefore, the engine settings that are immediately lower than this are 2850 RPM/+16 lb. That setting then becomes MIL and is continuous.

If my assumptions on this engne model is correct, all HTC would have to do is add the extra RPMs to the Spitfire IX's MIL/combat setting. I know this is not completely correct, but it seems as though HTC has tried to set up a compromise between what we would see as 2-stage WEP and a simple engine model by only applying a 5 min limit on the absolute max settings to engines of ALL planes.

[MiloMorai]

Spit IX Pilot's Notes:
Combat            3000/+15      5min
Max Take-off      3000/+12      none stated, assume 15min
Max Climbing      2850/+12      1h
Max Continuous    2650/+7       continuous

Max Take-off to 1000ft.
So what ever time it takes to get to 1000ft.

[SgtPappy]

Max Take-off to 1000ft.
So what ever time it takes to get to 1000ft.

Since the Spit XVI gets to 1000' in the blink of an eye, I guess that's not too much time spent on WEP.

Hopefully my post above is correct in terms of engine modeling then. It will keep things simple and will necessitate the minimum amount of adjustments to our current aircraft.

[dirt911]

Did i just open a can of worms by posting this topic?