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.

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. ;)

interesting, i was reading 'The Spitfire Story' by Alfred Price page 78, also very good reading.

guess it took them a while to 'initiate'

thanks for the book suggestion, will check it out.

EDIT

wow, if this is the book, might have to shop around, £75 pounds is a bit steep!

http://www.amazon.co.uk/Spitfire-His.../dp/0946219486

Sry but i dont see any conection with these both raports.

First raport is about Spitifire, Hurrciane, P36 and P40 - with not detail about types and no detail about type of airleons - if it was fabric or metal ones.

Second raport is clearly about Spitfire MVA with metal ailerons - but as i said i dont see conection between both raports.

Very poor roll rates of Spitfire from first raport suggest that it was with fabric covered ailerons. These confirm second roll rate chart which i posted with Spitfire MK V with metal airleons where roll rate is clearly improved over fabric covered ( from first test).

I got also another roll rate chart where roll rate of Spitfire MK V with metal airleons is about 100 deg/sec.

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...

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:

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).

Hmm, both reports are made by NACA, both reports are authored by William H. Philips. The first (Spitfire MkV metal ailerons) report dates January 1942. On page 13 it says that at 6000 ft altitude, 30 lbs stickforce, 59 degrees/sec was obtained.

The second (P-40 Hurri, Spit P-36) dates November 1942. Again made by NACA, both authored by the same William H. Philips.The roll chart of P-36, Hurricane, P-40, Spitfire shows ca. 65 deg/sec at 10000 ft altitude (as opposed to 6000 ft in the first report), 30 lbs stickforce. The report also references to NACA 868, the well known lateral control characteristics summary report, which notes that roll rate increases with altitude, and gives the neccessary conversion methods.

Quite simply the second report uses the figures obtained on the Spitfire Mark V with metal ailerons, tested by NACA earlier, and converted it to 10 000 feet.



First raport is about Spitifire, Hurrciane, P36 and P40 - with not detail about types and no detail about type of airleons - if it was fabric or metal ones.

Second raport is clearly about Spitfire MVA with metal ailerons - but as i said i dont see conection between both raports.

Its an assumption, but no, both reports show the same Spitfire with metal ailerons. In fact both reports show the same roll rates obtained.

Indeed the roll chart you posted for another Spitfire Mark V tested in the UK shows far higher roll rate than any other test result or source, UK or US. Its a pity we do not know anything about this Spitfire, but it seems this aircraft was either extraordinary good in this regard, or it had some non-standard aileron setup. We can only guess.

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.

Read the chart. The pilot used 50 lbf rather than 30 lbf. It is therefore hardly surprising that a higher roll rate was achieved because constant helix angle could be maintained to a higher TAS. Agreement between the charts is actually extremely good if you take this into account.

I already pointed this out in my last post, had you but taken the time to read it...

BTW:

• Roll rate is just a function of helix angle and TAS.
• Helix angle is a function of wing design and control deflection.
• Stick force to a first order approximation is proportional to Q.
• Deflection limited roll rate is therefore just proportional to TAS
• Force limited roll rate is inversely proportional to Q
• Roll rate achievable at altitude will vary in proportion to (TAS/EAS)

However, altitude itself doesn't "cause" this; the aeroplane knows nothing about its position relative to the geoid or to MSL. The relationship is simply caused by air density variation, and therefore it's quite possible for roll rate to be affected by the weather.

On a related note, the reduced helix angle associated with any given absolute roll rate as TAS increases is responsible for the reduction in roll damping at high altitude; again, the underlying mechanism is the TAS/EAS relationship, which means that roll damping is also a function of the weather conditions.

NB, the simplistic relationships explained above deliberately ignore the effects of compressibility upon stability & control. In particular, shockwave formation can dramatically reduce the effectiveness of control deflections by reducing the ability of control deflections to influence the flowfield upstream of the shock; stick forces are not reduced in proportion to the reduction in control effectiveness, and therefore pilot reports tend to read as though the controls have suddenly become heavier, when in fact they've just become less effective. But I digress...