Hurricane Roll Rate

[Kwiatek]

Originally Posted by Kurfürst

This is for a Spitfire Mark VA, with metal ailerons, tested by NACA in 1941. Not a Mark I with fabric ailerons.

I have a British mid-1940 report for the Spit I/Hurri I, basically it says the Hurricane is much better with regards to aileron control, though both are 'locked in cement' at high speed. Couldn't upload it yet..

Not true. These chart above is for SPit MK1/ Hurri MK1 with fabrics ailerons.


Here is roll rate for Spitfire with metal ailerons:

[madrebel]

kwiatek what relevance does that chart have on the game? it only shows spitVs. when there is a late 41/42 africa or channel mod with LF spitVs and 190A2s/3s then we can worry about that.

iirc the first test of metal ailerons were done on a spit2 in early 41.

[TheGrunch]

To show that the previous chart he posted was *not* a Spitfire with metal ailerons.

The conversion to the Merlin 45 engine would not affect the roll rate.

[Viper2000]

Originally Posted by TheGrunch

To show that the previous chart he posted was *not* a Spitfire with metal ailerons.

The two charts assume different stick forces, so it's hardly surprising that they look different. Agreement between the Spitfire Va(?) in the first chart and the full-wing Spitfire Vb in the second chart is pretty good at about 150 mph where both have their ailerons pegged on the stop.

It is also worth pointing out that there is quite a big difference between test roll rate and the roll rates achieved in service because of the nature of test procedure.

In this period, stick forces were generally measured by sending the test pilot into the air with a calibrated spring (often requisitioned from the nearest butcher's shop).

In order to get sensible results, tests need to be conducted under controlled conditions. It is no good just saying "roll as fast as you can", because that will tell you more about the pilot than the aeroplane.

So tests were conducted to a procedure, and the details of that procedure could dramatically affect the results (e.g., you can almost always roll a lot faster with help from the rudder than without it).

Likewise, force measurements needed to be performed with some care. Obviously you can only conduct measurements within the useful range of your equipment. If the scale only reads to 50 lbf then you can't measure 50 lbf properly, because once you hit 50 lbf on the scale, the actual meaning is >=50 lbf.

Of course, these aeroplanes weren't designed for the convenience of test pilots, so finding enough elbow room for constant force roll tests probably wasn't trivial.

All of these factors tend to reduce the measured roll rates somewhat; as such, "conservative" figures need not be the product of any kind of misinformation or conspiracy, and in fact might well emerge even against the wishes of the test organisation.

Comparisons with modern aeroplanes at airshows doesn't really stack up. Most "WWII" aeroplanes you can see flying today are not maintained in original condition (it's unrealistic to expect operators not to embody the latest airframe and engine modifications to reduce their costs and improve safety), and they often don't have guns and ammunition in their wings when performing at airshows . To get a real sense of this, compare and contrast the BBMF's oldest Spitfire with the Battle of Britain vintage Spitfire in the Imperial War Museum in London which AFAIK has be de-modded to genuine 1940 standard...

[TheGrunch]

Oh dear, I must have read the first chart in too much of a hurry, I was under the impression they were both at 50lbs. My apologies Kurfürst, madrebel. Thanks for the detailed explanation though Viper! The second chart will actually be very very useful to us if these later aircraft are added as a maximum steady roll rate chart since we know that the maximum figure in the force-displacement stick model in CoD is 50lbs, it's mentioned in the manual:

A regular human can do little more than 50 lbs of counter-pressure on the stick. This means that we have to model this virtually. Cliffs of Dover fully models various forces acting upon control surfaces. For example, a joystick in your hand fully deflected down is equal to 50 lbs of pressure.

Mind, the 30lbs one is just as useful for testing assuming we set the roll axis as linear and apply 3/5ths pressure using an external program or something similar (eg. set the 100% deadzone in stick settings to cover the last 2/5ths of stick travel).

[Ernst]

Originally Posted by Viper2000

The two charts assume different stick forces, so it's hardly surprising that they look different. Agreement between the Spitfire Va(?) in the first chart and the full-wing Spitfire Vb in the second chart is pretty good at about 150 mph where both have their ailerons pegged on the stop.

It is also worth pointing out that there is quite a big difference between test roll rate and the roll rates achieved in service because of the nature of test procedure.

In this period, stick forces were generally measured by sending the test pilot into the air with a calibrated spring (often requisitioned from the nearest butcher's shop).

In order to get sensible results, tests need to be conducted under controlled conditions. It is no good just saying "roll as fast as you can", because that will tell you more about the pilot than the aeroplane.

So tests were conducted to a procedure, and the details of that procedure could dramatically affect the results (e.g., you can almost always roll a lot faster with help from the rudder than without it).

Likewise, force measurements needed to be performed with some care. Obviously you can only conduct measurements within the useful range of your equipment. If the scale only reads to 50 lbf then you can't measure 50 lbf properly, because once you hit 50 lbf on the scale, the actual meaning is >=50 lbf.

Of course, these aeroplanes weren't designed for the convenience of test pilots, so finding enough elbow room for constant force roll tests probably wasn't trivial.

All of these factors tend to reduce the measured roll rates somewhat; as such, "conservative" figures need not be the product of any kind of misinformation or conspiracy, and in fact might well emerge even against the wishes of the test organisation.

Comparisons with modern aeroplanes at airshows doesn't really stack up. Most "WWII" aeroplanes you can see flying today are not maintained in original condition (it's unrealistic to expect operators not to embody the latest airframe and engine modifications to reduce their costs and improve safety), and they often don't have guns and ammunition in their wings when performing at airshows . To get a real sense of this, compare and contrast the BBMF's oldest Spitfire with the Battle of Britain vintage Spitfire in the Imperial War Museum in London which AFAIK has be de-modded to genuine 1940 standard...

50 lbs = 22Kg is the maximun force a human can do in a "lateral" movement of the arms in the stick right? Since you are talking about ailerons deflection i guess its ok.

For pull or push (back and forward) is not quite a pull. Certainly i can grab 50kg with both hands for some seconds. (50 kg is a cement sack). Are you capable to grab a cement sack? The possible force to be applied in the elevatot i guess is much higher.

But certainly is very unpleasant to grab 22 kg to sides or 50 kg back and forward in a combat. Much of the pilot concentration must go to trying deflect the controls while tracking the enemy. Gunnery in this conditions is near impossible. This is a sensation we ll never experience in a sim.

[fruitbat]

Originally Posted by madrebel

kwiatek what relevance does that chart have on the game? it only shows spitVs. when there is a late 41/42 africa or channel mod with LF spitVs and 190A2s/3s then we can worry about that.

iirc the first test of metal ailerons were done on a spit2 in early 41.

not that is particularly relevant, but Jeffrey Quill first tested a spit in Nov 1940 with metal ailerons and then flew it to Tangmere, where it was also flown by the commander of 602 squadron Sandy Johnstone.

afterwards a crash program was initiated to fit all front line spits with these ailerons.

[Kurfürst]

Originally Posted by fruitbat

not that is particularly relevant, but Jeffrey Quill first tested a spit in Nov 1940 with metal ailerons and then flew it to Tangmere, where it was also flown by the commander of 602 squadron Sandy Johnstone.

afterwards a crash program was initiated to fit all front line spits with these ailerons.

Metal ailerons were started to be fitted in around April 1941 to Mark Vs.

[fruitbat]

Originally Posted by Kurfürst

Metal ailerons were started to be fitted in around April 1941 to Mark Vs.

i'm curious as to what your basing that on, cause it doesn't tally with what i'm reading in front of me.

[Kurfürst]

Spitfire the History, page 142, Chapter "A temporary expedient" (ie. Mark V)

Letter dated 18 June 1940 (my bad, not april) from Sholto-Dougles, C-in-C of FC is quoted, saying that despite decision taken in November 1940, Spitfires are still delivered with fabric covered ailerons and its only now that production line started to use metal ailerons. Large number of Spitfires need retrofit, but Supermarine is only able to retrofit at 10 sets of ailerons per week.

Great book btw, suggest order from publisher, dirt cheap. Mordin out.