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FM/DM threads Everything about FM/DM in CoD

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  #1  
Old 04-21-2011, 09:29 PM
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Redroach Redroach is offline
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Unhappy Hurricane engine torque

Introduction: Yes, I know about engine torque and propwash and the like. But in the Hurricane (Rotol), engine torque seems to be quite excessive. I'm no expert on that but early-war engines shouldn't have the power to drag the whole plane into a steep spin if you leave it alone for a short while (depends on engine mounting, too, I think).

Basically, I've not yet been able to find a combination of throttle/prop angle/mixture etc. to get the hurricane flying straight and level. So you have the options of either grab the stick and apply aileron, probably for hours on end, or apply such excessive rudder trim that your plane basically flies sideways.

Planes without aileron trim in Il-2 1946 always (or mostly ) had some point where the plane was trimmed - i.e. the Bf-109 was trimmed in cruise flight - 50-55% throttle. And if going combat power, the engine torque was probably thrice as light than in the current CoD hurricane (late- war 109s included (!) )

As said, I'm no engine buff and I AM a realism fan, but still, guts tell me that the engine torque of the hurricane is just too much.

And I can't remember strong engine torque in 1946's Hurricane either.
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Old 04-21-2011, 10:57 PM
DC338 DC338 is offline
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Torque in the game is far too little not far too much.

Approach to stall in landing config and rapidly apply full power should produce a torque roll that it almost impossible to counter act yet in game is easy.
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Old 04-21-2011, 11:12 PM
jdbecks jdbecks is offline
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I think you should back your statement up with technical support/proof instead of theorys..Not that I think your right or wrong, but when it comes to flight models only authentic data should be used/supplied then the changes made to the flight model can follow. Otherwise the simulation starts to become to in accurate.
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Old 04-22-2011, 12:07 AM
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With my OP, I didn't just mean: "reduce engine torque by some arbitrary value". Instead, I am of the opinion that the Hurricane FM should be looked into. If it's really correct the way it is now (contrary to the FM in 1946), then so be it. However, I still think engine torque IS excessive in the Hurricane ^-^
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Old 04-22-2011, 12:18 PM
Peril Peril is offline
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I think what the man wants is the ability to manually change the trim on the ground, bending trim tabs etc. So the plane whilst in 'cruise' speed is trimmed neutral in roll. On most early war planes this 'is' the historic way to do it Only here it seems planes are set with no counter trim at all, which is 'not' historic. Fixed trim counters the 'average' of the torque effect. Therefore with engine off you roll right slightly, engine on you roll left slightly, rather than all left, all the time.

However, I can find no evidence of trim tabs on Hurri ailerons, I also found the below document confirms the stick was needing to be held to the right a lot of the time.

I am concerned about adverse Yaw, and below I have the document to reference it @ 12 deg. Feels like we are seeing more in game just not sure how we measure that?

------------------------------------------

Memorandum report Army Airforces Material Command.

Measurement of the flying qualities of a Hawker Hurricane airplane.

Points of interest.

Ailerons we asymmetric in application as follows:

Right
21.5 down, 20.6 up
Left
19.2 down 22.4 up

Found this quantification of the adverse yaw:

The maximum angle of yaw due to full application of the ailerons was 12deg.

Effects of yaw on roll were minimal.


If anyone needs the document I have a copy.

Last edited by Peril; 04-22-2011 at 12:51 PM.
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Old 04-22-2011, 12:33 PM
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hmm maybe you got a point. But I still find the un-countered engine torque itself is just too much right now.
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Old 04-22-2011, 12:45 PM
Viper2000 Viper2000 is offline
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Most of the aeroplanes I've flown in the sim will actually sort themselves out in cruise. However, you have to be flying at the correct speed, boost, rpm and altitude, otherwise it's not going to work.

These aeroplanes weren't designed for low altitude cruising.

Equally, cruising wasn't really a very good idea because of the time taken to get the mixture rich, prop into fine pitch/high rpm and boost to combat levels and speed to something sensible for combat.

This was learned the hard way in 1941 by Spitfire V pilots over northern France when the first Fw190s arrived on the scene.

As for actual values of torque, if we get +12 then combat power would be 1310 bhp at 3000 engine rpm. The reduction gear of the Merlin III is 0.477:1, so the prop rpm is about 1431.

bhp = torque[lb-ft]*rpm/5252

bhp*5252 = torque[lb-ft]*rpm

bhp*5252/rpm = torque[lb-ft]

Filling in the numbers I get roughly 4808 lb-ft. The maximum weight of the aeroplane is rather less than 7000 lb. Go figure...
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Old 04-24-2011, 11:26 AM
TomcatViP TomcatViP is offline
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Hi Vip,

1310HP in combat setting during the BoB days ???!!! Seems awfully over estimated IMHO

~S
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Old 04-24-2011, 11:32 AM
Sternjaeger II Sternjaeger II is offline
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Quote:
Originally Posted by TomcatViP View Post
Hi Vip,

1310HP in combat setting during the BoB days ???!!! Seems awfully over estimated IMHO

~S
Viper uses a thing called "evidence" to support his statements, I'm sure he's about to give you a good demonstration

As for torque, from what I've seen and heard so far it really looks like it's seriously undermodelled.

Aeroplanes with more than 600hp engines have an incredible torque tendency: the T-6 and Mustang will both tend to torque themselves out of the top of a looping, u need to keep em aligned with rudder and aileron work all the time even if you're all trimmed for aerobatics.
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Old 04-24-2011, 12:30 PM
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Redroach Redroach is offline
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Quote:
Originally Posted by Viper2000 View Post
Most of the aeroplanes I've flown in the sim will actually sort themselves out in cruise. However, you have to be flying at the correct speed, boost, rpm and altitude, otherwise it's not going to work.

These aeroplanes weren't designed for low altitude cruising.

Equally, cruising wasn't really a very good idea because of the time taken to get the mixture rich, prop into fine pitch/high rpm and boost to combat levels and speed to something sensible for combat.

This was learned the hard way in 1941 by Spitfire V pilots over northern France when the first Fw190s arrived on the scene.

As for actual values of torque, if we get +12 then combat power would be 1310 bhp at 3000 engine rpm. The reduction gear of the Merlin III is 0.477:1, so the prop rpm is about 1431.

bhp = torque[lb-ft]*rpm/5252

bhp*5252 = torque[lb-ft]*rpm

bhp*5252/rpm = torque[lb-ft]

Filling in the numbers I get roughly 4808 lb-ft. The maximum weight of the aeroplane is rather less than 7000 lb. Go figure...
Hmm i can't figure... could you please explain what that means for me?
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