Roll rate

[Francis marliere]

Gentlemen,

I understand that roll rate was something crucial for WWII aircrafts. Unfortunately, finding information about it is incredibly difficult. I couldn't get any reliable data except for a very few planes. Could you please provide me some data or sources ?

Thanks for your help,

Francis Marliere

 

[Jabberwocky]

Gentlemen,

I understand that roll rate was something crucial for WWII aircrafts. Unfortunately, finding information about it is incredibly difficult. I couldn't get any reliable data except for a very few planes. Could you please provide me some data or sources ?

Thanks for your help,

Francis Marliere

Of the top of my head:

NACA 868, which is a compilation of roll-rates of Allied WW2 fighters. Might be available at ww2aircraftperformance.com

There is a test by the RAF comparing the roll rate of the Spitfire I to the Hurricane I, P-36 and P-40. Also one comparing the roll of the Spitfire I compared to the Bf-109E.

There is also a RAAF test of the Spitfire V compared to the Zero.

There was a German document floating around a few years ago for 109G lateral control.

Hawker did some Tempest roll-rate tests, again available at ww2aircraftperformance.com

 

[renrich]

"America's Hundred Thousand" by Francis Dean has a lot of roll rate info about American fighters.

 

[Francis marliere]

Gentlemen,

thank you for your kind answers. However, I have already the documents you are talking about, but they are not enough. There are still plenty of planes (such as Fulmar or Gladiator, French and Italian planes, etc.) for which I have no data. There are also some planes which are rated as good rollers by some sources and bad by others : in the NACA document, the spitfire (with normal wings) rolls at 105° per second at 200 mph ; in another it's 70° ; in a third it's 25° (a bit less than 2 seconds for a 45° bank) ...
As you see, it is not simple ...

Best regards,

Francis Marliere

 

[Hop]

With any test results you have to know how they were conducted and on which particular types.

NACA 868 uses 50 lbs stick force for most aircraft. Higher stick forces will produce higher roll rates, lower stick forces lower roll rates.

As regards the Spitfire, the wings were stiffened several times during the service life.

The Spitfire I with fabric ailerons rolled much worse. The Spitfire Vb with metal ailerons was better. The Vc had further wing strengthening. I believe it's a Vc in NACA 868.

I know of tests for the Spitfire I with fabric ailerons, there are other tests for other unidentified Spitfire types. At least one Australian tests uses 30lbs stick force and gives much lower results.

 

[Jabberwocky]

Gentlemen,

thank you for your kind answers. However, I have already the documents you are talking about, but they are not enough. There are still plenty of planes (such as Fulmar or Gladiator, French and Italian planes, etc.) for which I have no data. There are also some planes which are rated as good rollers by some sources and bad by others : in the NACA document, the spitfire (with normal wings) rolls at 105° per second at 200 mph ; in another it's 70° ; in a third it's 25° (a bit less than 2 seconds for a 45° bank) ...
As you see, it is not simple ...

Best regards,

Francis Marliere

Time for 45 degree bank is a little misleading.

It can take as much as .3 of a second for a roll to initiate. The aircraft doesn't initiate a roll at 70 or 105 deg a sec, it does take some time to overcome momentum and for full stick force to be applied.

There is a difference between steady state roll rate (the best roll at a given speed) and time to bank.

Spitfire roll rates are complicated, thanks to the number of different hinge, aileron and aileron skinning types they were fitted with. The rate of roll got progressively better through the war.

The Mk I with fabric ailerons topped out at about 65 deg a sec. When this was switched to metal skinned ailerons, it jumped to about 90 deg a sec, but was also better through the entire speed range. The Mk Va/b was roughly the same, perhaps a little improved, and control was considered better at higher speeds for the Mk Vc onwards (and types that used the C and E wings).

 

[Francis marliere]

That makes sense. Thank you for your explanations.