Hurricane engine torque

[DC338]

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.

[jdbecks]

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.

[Redroach]

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 ^-^

[Peril]

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.

[Redroach]

hmm maybe you got a point. But I still find the un-countered engine torque itself is just too much right now.

[Viper2000]

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...

[TomcatViP]

Hi Vip,

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

~S

[Sternjaeger II]

Originally Posted by TomcatViP

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.

[Viper2000]

1310 bhp at +12 psi, 3000 rpm at 9000'.

R.M.1.S. rating.

Alternatively, on 87 octane, you'd get 1000 bhp at +6¼ psi, 3000 rpm at 15500' (which is preserved in the R.M.2.S rating).

Harvey-Bailey, A. H. 1995 The Merlin in Perspective - the combat years 4th edition. Derby: Rolls-Royce Heritage Trust.

AFAIK these are static ratings (ie without intake ram effect; therefore the FTHs are somewhat lower than would be achieved during a level speed run).

///

4800 lb-ft of torque into rather less than 7000 lbm of aeroplane means that the torque at the prop shaft would be able to oppose the entire weight of the aeroplane with a moment arm a bit more than 6" long.

To put it another way, a hurricane has a wingspan of 40'; so the semi-span is 20'.

The torque is therefore equivalent to a 240 lb mass sat on one wing tip.

There is also propwash and p-factor to consider.

[Redroach]

Originally Posted by Viper2000

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?