# WWII Aircraft Roll-Rates



## Zipper730 (Jul 31, 2017)

It has to do with video footage of aircraft executing rolls versus the stated roll rate: It seemed they were rolling faster than stated on paper.

I'm curious how they derived the calculations.


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## tyrodtom (Jul 31, 2017)

They would time it with a stop watch, and at different air speeds and altitudes. Any aircraft would have certain conditions when it would be at it's best, but not necessarily the same conditions that another aircraft would be best.
" It seemed " is hardly a accurate method of measurement.


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## Zipper730 (Jul 31, 2017)

The video seemed to depict a roll rate based on timing as well and it appeared to be faster than listed...


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## Greyman (Aug 5, 2017)

Is there any guarantee the video (and/or film that it was derived from) is playing at the proper speed?


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## Zipper730 (Aug 5, 2017)

Greyman said:


> Is there any guarantee the video (and/or film that it was derived from) is playing at the proper speed?


Good point... I'll try and see if I can find it.


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## pbehn (Aug 5, 2017)

For many aircraft the roll rate is not a constant. A PR Spitfire will roll better with empty tanks than full ones. I believe some roll tests stipulated the force used because pilot strength isn't constant either.


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## Venturi (Aug 13, 2017)

Moment of inertia, stick forces (dependent on design and airspeed), airspeed, altitude (air density), and pilot strength are all factors...


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