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FM/DM threads Everything about FM/DM in CoD

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  #11  
Old 10-15-2012, 10:43 PM
klem's Avatar
klem klem is offline
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OK

Yes ROC is not right.
You might like to think about:
Z_Accel_x = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 0);
Z_Accel_y = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 1);
Z_Accel_z = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 2);

x = accleration fore/aft
y = accleration left/right
z = accleration up/down

z lets you know if you are accelerating up or down (changing height). I 'filter' by eyeball when assessing the records I get back, looking for 1.0, +/- about 0.03 to get a stable string of records. I also cross check for stable altitude +/- a few feet but within about 20 feet of the test altitude and for the IAS or TAS staying at best speed for good level flight. Its surprising how quickly it settles down, maybe 5 minutes, and how stable and predictable the returns are even over minor changes in height and Z_Accel_z ('G'). Makes it easy to see where speed is changing and why and to pick out the most appropriate result.
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Last edited by klem; 10-15-2012 at 10:46 PM.
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  #12  
Old 10-16-2012, 12:30 AM
*Buzzsaw* *Buzzsaw* is offline
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Salute

I did two hours of tests of the Spit IA and Spit IA 100 octane, less systematic to be sure, but it was online on the ATAG server.

I found all Merlin equipped aircraft had some degree of misfiring and cutting out at certain altitudes, with the effect happening more frequently the higher the aircraft climbed. This became more pronounced when maneuvering accompanied the climb. The effect came on at lower boost levels when the rpm was high, and conversely required higher boost at lower rpms. It was also more likely to happen when you increased the throttle, (boost control) or rpm, (selected finer pitch) rapidly. The effect begins with small stutters, you can see your rpm gauge kick, then as you increase the rpm or boost, the effect escalates into full on misfiring and cutting out. This effect happened without any overheating, and no damage resulted. After doing nearly an hour of testing in a Spit IA 100 octane, with probably 10 minutes worth of misfiring/backfiring, I was able to drop down to below 10,000 ft and use 2800 rpm and +6 1/4 boost to shoot down a 109.

This effect is entirely unhistorical, the carbureted Merlin had no tendency to misfire or backfire at neutral or positive G's, and it was more capable of sustaining high rpms and full throttle at higher altitudes than it was down low. (because the max. boost which could be obtained was lower, especially over critical altitude)

The effect began as low as 8000 ft as far as I could determine, I got misfiring and cutting out of the engine of the Spit IA 100 Oct at 2900 rpm and +6 1/4 boost at that altitude. As mentioned, this occurred even when the engine temperatures were at low levels, 85 degrees C.

I found the Spitfire IA 100 octane was the worst aircraft for this effect, and it was prevented from getting over much more than 23,000 ft in a climb. At that altitude, it could not manage more than +0 boost/3000 rpm without misfiring. It was necessary to increase rpms to 3000 in order to register any kind of climb at that altitude.

Here are some samples of altitudes/boost levels/rpms when I got the onset of misfiring in the Spit IA 100 octane:

14,500 ft: +5 boost 2700 rpm

16,500 ft: +4 boost 2700 rpm

18,500 ft: +3 1/2 2700 rpm

20,000 ft: +2 boost 2700 rpm

21,000 ft: +1 boost 3000 rpm (as I got higher, I found reducing boost and increasing rpm was the best solution for max. climb)

22,000 ft: +1/2 boost 3000 rpm

The Hurricanes were much less likely to see this effect, in my experience, the only occasion I found the 100 octane Rotol Hurricane had this happen was at 2800 rpm/+6 1/4 boost at 16,500 ft, although I was not looking for the effect at the time, I had thought it was limited to the Spits, was just flying combat.

There was also another anomaly with the Merlins, in that there is a pronounced tendency to overheat sooner at higher altitudes. Flying at 2700 rpm/+1 boost at Sea level will see the engine operating at 85 C, but at 21,000 ft, using exactly the same boost and rpm and with the same radiator settings, temperatures will be up at 95 degrees. As anyone knows, temperature should be more easily controlled at higher altitudes, not the opposite.

I have been told others are getting different results, and it may be the installation, although my own wingman was also getting the effect, and many others have reported it.

As it stands, the Spitfires especially are still crippled for combat over approx. 12,000 ft, and do not achieve their historical climbs or speeds.

I plan to do some more testing tonight after verifying my Steam installation, deleting the cache and re-downloading the latest patch.

Last edited by *Buzzsaw*; 10-16-2012 at 12:43 AM.
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  #13  
Old 10-16-2012, 01:34 AM
trademe900 trademe900 is offline
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Yes you are right all the merlins apart from the Spit 1 two stage prop have overheating issues when higher.

this engine cutting out bug is ridiculous.
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  #14  
Old 10-16-2012, 06:56 AM
klem's Avatar
klem klem is offline
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Quote:
Originally Posted by *Buzzsaw* View Post
Salute

I did two hours of tests of the Spit IA and Spit IA 100 octane, less systematic to be sure, but it was online on the ATAG server.

I found all Merlin equipped aircraft had some degree of misfiring and cutting out at certain altitudes, with the effect happening more frequently the higher the aircraft climbed. This became more pronounced when maneuvering accompanied the climb. The effect came on at lower boost levels when the rpm was high, and conversely required higher boost at lower rpms. It was also more likely to happen when you increased the throttle, (boost control) or rpm, (selected finer pitch) rapidly. The effect begins with small stutters, you can see your rpm gauge kick, then as you increase the rpm or boost, the effect escalates into full on misfiring and cutting out. This effect happened without any overheating, and no damage resulted. After doing nearly an hour of testing in a Spit IA 100 octane, with probably 10 minutes worth of misfiring/backfiring, I was able to drop down to below 10,000 ft and use 2800 rpm and +6 1/4 boost to shoot down a 109.

This effect is entirely unhistorical, the carbureted Merlin had no tendency to misfire or backfire at neutral or positive G's, and it was more capable of sustaining high rpms and full throttle at higher altitudes than it was down low. (because the max. boost which could be obtained was lower, especially over critical altitude)

The effect began as low as 8000 ft as far as I could determine, I got misfiring and cutting out of the engine of the Spit IA 100 Oct at 2900 rpm and +6 1/4 boost at that altitude. As mentioned, this occurred even when the engine temperatures were at low levels, 85 degrees C.

I found the Spitfire IA 100 octane was the worst aircraft for this effect, and it was prevented from getting over much more than 23,000 ft in a climb. At that altitude, it could not manage more than +0 boost/3000 rpm without misfiring. It was necessary to increase rpms to 3000 in order to register any kind of climb at that altitude.

Here are some samples of altitudes/boost levels/rpms when I got the onset of misfiring in the Spit IA 100 octane:

14,500 ft: +5 boost 2700 rpm

16,500 ft: +4 boost 2700 rpm

18,500 ft: +3 1/2 2700 rpm

20,000 ft: +2 boost 2700 rpm

21,000 ft: +1 boost 3000 rpm (as I got higher, I found reducing boost and increasing rpm was the best solution for max. climb)

22,000 ft: +1/2 boost 3000 rpm

The Hurricanes were much less likely to see this effect, in my experience, the only occasion I found the 100 octane Rotol Hurricane had this happen was at 2800 rpm/+6 1/4 boost at 16,500 ft, although I was not looking for the effect at the time, I had thought it was limited to the Spits, was just flying combat.

There was also another anomaly with the Merlins, in that there is a pronounced tendency to overheat sooner at higher altitudes. Flying at 2700 rpm/+1 boost at Sea level will see the engine operating at 85 C, but at 21,000 ft, using exactly the same boost and rpm and with the same radiator settings, temperatures will be up at 95 degrees. As anyone knows, temperature should be more easily controlled at higher altitudes, not the opposite.

I have been told others are getting different results, and it may be the installation, although my own wingman was also getting the effect, and many others have reported it.

As it stands, the Spitfires especially are still crippled for combat over approx. 12,000 ft, and do not achieve their historical climbs or speeds.

I plan to do some more testing tonight after verifying my Steam installation, deleting the cache and re-downloading the latest patch.
+1

Good Report.
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klem
56 Squadron RAF "Firebirds"
http://firebirds.2ndtaf.org.uk/



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  #15  
Old 10-16-2012, 08:16 AM
*Buzzsaw* *Buzzsaw* is offline
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Salute

I retested online on ATAG tonight after first verifying my Steam install to the official patch, then downloading a new copy of the new patch and installing it after deleting cache.

I still got the misfiring and engine shudders in both the Hurricane I 100 octane and Spitfire IA 100 octane, with the Spitfire's onset being approx. 8-9000 ft, and the Hurricane at about 14-15,000.

Contrary to my previous impression, this time after more experimentation I've decided the issue is brought on mostly by the level of boost used, and that rpm has very little to do with it, except at very high altitudes.

No way to prove it, but I suspect this has something to do with the negative G cutout modelling and is also related to the modelled brief engine stutters and coughs which happen at any altitude when you increase throttle rapidly on the Merlins. My impression is the negative G is somehow activated by the sudden yaw of the aircraft, or perhaps the torque of the engine when throttle is suddenly opened, or at higher altitudes when higher throttle is used.

In any case, it shouldn't be characteristic of the Merlin.
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  #16  
Old 10-16-2012, 09:38 AM
macro macro is offline
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Quote:
Originally Posted by *Buzzsaw* View Post
Salute

I did two hours of tests of the Spit IA and Spit IA 100 octane, less systematic to be sure, but it was online on the ATAG server.

I found all Merlin equipped aircraft had some degree of misfiring and cutting out at certain altitudes, with the effect happening more frequently the higher the aircraft climbed. This became more pronounced when maneuvering accompanied the climb. The effect came on at lower boost levels when the rpm was high, and conversely required higher boost at lower rpms. It was also more likely to happen when you increased the throttle, (boost control) or rpm, (selected finer pitch) rapidly. The effect begins with small stutters, you can see your rpm gauge kick, then as you increase the rpm or boost, the effect escalates into full on misfiring and cutting out. This effect happened without any overheating, and no damage resulted. After doing nearly an hour of testing in a Spit IA 100 octane, with probably 10 minutes worth of misfiring/backfiring, I was able to drop down to below 10,000 ft and use 2800 rpm and +6 1/4 boost to shoot down a 109.

This effect is entirely unhistorical, the carbureted Merlin had no tendency to misfire or backfire at neutral or positive G's, and it was more capable of sustaining high rpms and full throttle at higher altitudes than it was down low. (because the max. boost which could be obtained was lower, especially over critical altitude)

The effect began as low as 8000 ft as far as I could determine, I got misfiring and cutting out of the engine of the Spit IA 100 Oct at 2900 rpm and +6 1/4 boost at that altitude. As mentioned, this occurred even when the engine temperatures were at low levels, 85 degrees C.

I found the Spitfire IA 100 octane was the worst aircraft for this effect, and it was prevented from getting over much more than 23,000 ft in a climb. At that altitude, it could not manage more than +0 boost/3000 rpm without misfiring. It was necessary to increase rpms to 3000 in order to register any kind of climb at that altitude.

Here are some samples of altitudes/boost levels/rpms when I got the onset of misfiring in the Spit IA 100 octane:

14,500 ft: +5 boost 2700 rpm

16,500 ft: +4 boost 2700 rpm

18,500 ft: +3 1/2 2700 rpm

20,000 ft: +2 boost 2700 rpm

21,000 ft: +1 boost 3000 rpm (as I got higher, I found reducing boost and increasing rpm was the best solution for max. climb)

22,000 ft: +1/2 boost 3000 rpm

The Hurricanes were much less likely to see this effect, in my experience, the only occasion I found the 100 octane Rotol Hurricane had this happen was at 2800 rpm/+6 1/4 boost at 16,500 ft, although I was not looking for the effect at the time, I had thought it was limited to the Spits, was just flying combat.

There was also another anomaly with the Merlins, in that there is a pronounced tendency to overheat sooner at higher altitudes. Flying at 2700 rpm/+1 boost at Sea level will see the engine operating at 85 C, but at 21,000 ft, using exactly the same boost and rpm and with the same radiator settings, temperatures will be up at 95 degrees. As anyone knows, temperature should be more easily controlled at higher altitudes, not the opposite.

I have been told others are getting different results, and it may be the installation, although my own wingman was also getting the effect, and many others have reported it.

As it stands, the Spitfires especially are still crippled for combat over approx. 12,000 ft, and do not achieve their historical climbs or speeds.

I plan to do some more testing tonight after verifying my Steam installation, deleting the cache and re-downloading the latest patch.
+1. You need to put this in bug thread
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  #17  
Old 10-16-2012, 10:43 AM
Kurfürst Kurfürst is offline
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Quote:
Originally Posted by *Buzzsaw* View Post
There was also another anomaly with the Merlins, in that there is a pronounced tendency to overheat sooner at higher altitudes. Flying at 2700 rpm/+1 boost at Sea level will see the engine operating at 85 C, but at 21,000 ft, using exactly the same boost and rpm and with the same radiator settings, temperatures will be up at 95 degrees. As anyone knows, temperature should be more easily controlled at higher altitudes, not the opposite.
That doesn't seem to be correct, at higher altitude though the air is much colder, at the same time it's also much less dense. Without air to contact with, the radiator may find it more difficult to transfer heat. High altitude engines typically required larger coolers for that reason.

Generally, overheating seems to have been changed accross the sim, 109Es for example are now seem to overheat very easily and are much more difficult to keep in line. Their cooling system can't handle engine heat at historical settings.
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Il-2Bugtracker: Feature #200: Missing 100 octane subtypes of Bf 109E and Bf 110C http://www.il2bugtracker.com/issues/200
Il-2Bugtracker: Bug #415: Spitfire Mk I, Ia, and Mk II: Stability and Control http://www.il2bugtracker.com/issues/415

Kurfürst - Your resource site on Bf 109 performance! http://kurfurst.org
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  #18  
Old 10-16-2012, 11:45 AM
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ATAG_Snapper ATAG_Snapper is offline
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+1

Nice work, Buzzsaw.

Quote:
Originally Posted by *Buzzsaw* View Post
Salute

I did two hours of tests of the Spit IA and Spit IA 100 octane, less systematic to be sure, but it was online on the ATAG server.

I found all Merlin equipped aircraft had some degree of misfiring and cutting out at certain altitudes, with the effect happening more frequently the higher the aircraft climbed. This became more pronounced when maneuvering accompanied the climb. The effect came on at lower boost levels when the rpm was high, and conversely required higher boost at lower rpms. It was also more likely to happen when you increased the throttle, (boost control) or rpm, (selected finer pitch) rapidly. The effect begins with small stutters, you can see your rpm gauge kick, then as you increase the rpm or boost, the effect escalates into full on misfiring and cutting out. This effect happened without any overheating, and no damage resulted. After doing nearly an hour of testing in a Spit IA 100 octane, with probably 10 minutes worth of misfiring/backfiring, I was able to drop down to below 10,000 ft and use 2800 rpm and +6 1/4 boost to shoot down a 109.

This effect is entirely unhistorical, the carbureted Merlin had no tendency to misfire or backfire at neutral or positive G's, and it was more capable of sustaining high rpms and full throttle at higher altitudes than it was down low. (because the max. boost which could be obtained was lower, especially over critical altitude)

The effect began as low as 8000 ft as far as I could determine, I got misfiring and cutting out of the engine of the Spit IA 100 Oct at 2900 rpm and +6 1/4 boost at that altitude. As mentioned, this occurred even when the engine temperatures were at low levels, 85 degrees C.

I found the Spitfire IA 100 octane was the worst aircraft for this effect, and it was prevented from getting over much more than 23,000 ft in a climb. At that altitude, it could not manage more than +0 boost/3000 rpm without misfiring. It was necessary to increase rpms to 3000 in order to register any kind of climb at that altitude.

Here are some samples of altitudes/boost levels/rpms when I got the onset of misfiring in the Spit IA 100 octane:

14,500 ft: +5 boost 2700 rpm

16,500 ft: +4 boost 2700 rpm

18,500 ft: +3 1/2 2700 rpm

20,000 ft: +2 boost 2700 rpm

21,000 ft: +1 boost 3000 rpm (as I got higher, I found reducing boost and increasing rpm was the best solution for max. climb)

22,000 ft: +1/2 boost 3000 rpm

The Hurricanes were much less likely to see this effect, in my experience, the only occasion I found the 100 octane Rotol Hurricane had this happen was at 2800 rpm/+6 1/4 boost at 16,500 ft, although I was not looking for the effect at the time, I had thought it was limited to the Spits, was just flying combat.

There was also another anomaly with the Merlins, in that there is a pronounced tendency to overheat sooner at higher altitudes. Flying at 2700 rpm/+1 boost at Sea level will see the engine operating at 85 C, but at 21,000 ft, using exactly the same boost and rpm and with the same radiator settings, temperatures will be up at 95 degrees. As anyone knows, temperature should be more easily controlled at higher altitudes, not the opposite.

I have been told others are getting different results, and it may be the installation, although my own wingman was also getting the effect, and many others have reported it.

As it stands, the Spitfires especially are still crippled for combat over approx. 12,000 ft, and do not achieve their historical climbs or speeds.

I plan to do some more testing tonight after verifying my Steam installation, deleting the cache and re-downloading the latest patch.
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  #19  
Old 10-16-2012, 04:28 PM
ACE-OF-ACES's Avatar
ACE-OF-ACES ACE-OF-ACES is offline
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Quote:
Originally Posted by klem View Post
Yes ROC is not right.
You might like to think about:
Z_Accel_x = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 0);
Z_Accel_y = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 1);
Z_Accel_z = cur_Plane.getParameter(part.ParameterTypes.Z_Overl oad, 2);

x = accleration fore/aft
y = accleration left/right
z = accleration up/down

z lets you know if you are accelerating up or down (changing height).
Not right? I guess that depends on your point of view, in either case, using the ROC velocity or accelerations to filter the MAX TAS is better than using neither! The only down side to using the accelerations is they are never zero, so you will have to do some testing and thinking about what values of acceleration to use as the pass fail.. Where as the velocity is a little more intuitive, granted, the velocity alone has issues, in that a transition from the pos limit to the neg limit through zero could result in a bad MAX TAS being called good, where as using the acceleration would not be fooled by such a transition.

Quote:
Originally Posted by klem View Post
I 'filter' by eyeball when assessing the records I get back, looking for 1.0, +/- about 0.03 to get a stable string of records. I also cross check for stable altitude +/- a few feet but within about 20 feet of the test altitude and for the IAS or TAS staying at best speed for good level flight. Its surprising how quickly it settles down, maybe 5 minutes, and how stable and predictable the returns are even over minor changes in height and Z_Accel_z ('G'). Makes it easy to see where speed is changing and why and to pick out the most appropriate result.
The eyeball method is great when you have just a few of your own tests to review.. But it starts to become a very big task once the number of tests increases or you have to start reviewing the results of other peoples tests.. Which is something I use to do for people 10+ years ago when this sort of testing was done with IL-2.. But these days I am just too busy to do that, which is why it is my goal is to provide tools that anyone can to use that automate such tedious process and to make it more standardized.
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Theres a reason for instrumenting a plane for test..
That being a pilots's 'perception' of what is going on can be very different from what is 'actually' going on.
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  #20  
Old 10-16-2012, 04:35 PM
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ACE-OF-ACES ACE-OF-ACES is offline
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Quote:
Originally Posted by *Buzzsaw* View Post
I plan to do some more testing tonight after verifying my Steam installation, deleting the cache and re-downloading the latest patch.
Nice work Buzz!

Hey, if your interested, I have an OFFLINE single mission you can use for level speed testing here..

http://forum.1cpublishing.eu/showthread.php?t=34964

Note I have placed ~10 miles worth of RED FLASHING RINGS at each test altitudes to make it easier to fly level..

I am also working on a C# script file for that mission to log the data as you fly that provides you a heads up display (HUD) of your altitude, velocity, ROC, etc. Let me know if your interested in testing out that script
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Theres a reason for instrumenting a plane for test..
That being a pilots's 'perception' of what is going on can be very different from what is 'actually' going on.
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