Official Fulqrum Publishing forum - Hurricane & Spitfire control characteristics

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- - Hurricane & Spitfire control characteristics (http://forum.fulqrumpublishing.com/showthread.php?t=31181)

I've no problem to outturn a co-energy 109 and getting a firing solution with the Rotol-Hurri.

Quote:

Originally Posted by Kurfürst (Post 409830)

I did a quick measurements of roll rates for the Hurricane (Rotol) and the Spitfire Mk IIa. I climbed to sufficient altitude, and then entered a 30-45 degree dive to get the aircraft up to 400 mph IAS, then rolled them to the right 90 degrees and measured the time required with a stopwatch.

The RAE testing noted in the first post gives 2 secs for Hurricane for a 90 degree roll and 8 secs for the Spitfire under maximum effort.

I've got 2.5 secs (instead of 8 secs) for the Spitfire Mk II and around 3 secs for the Hurricane Mk I Rotol (instead of 2 secs)

Conclusion:

The Spitfire Mk. IIa's roll rate is overmodelled by a factor of 3.2 (!!), ie. it rolls 3.2 times faster at 400 mph IAS than it should be.

The Hurricane Mk. I Rotol roll rate is undermodelled by a factor of 1.5 , ie. it rolls 1.5 times slower at 400 mph IAS than it should be.

A roll rate of 90 degrees in 8 secs. does not make any sense at all.
I just looked over the document and considering typos and transcription errors, I'm willing to bet that it should read 3 seconds instead of 8 seconds.

Mh. I have some concerns if the report should be taken as a basis for FM development.

It clearly says that the authors of the report have some doubts about their finding as it does not entirely fit with reports from pilots.

The very first page says that both the Hurricane and the Spit were reported to be heavy on ailerons at high speeds while the Hurricane was measured to make the bank of 90° in 2 secs while the Spit's roll rate was measured to 8sec. It is obviously a discrepancy between pilots' complaints about the heaviness of BOTH aircraft and the measurements made on two individual aircraft with one being considerably lighter than the other.

The authors encouraged to contact Fighter Command in order to find out if the Hurricane used for measurement was too light or the used Spit too heavy.

I think this report is not a good base for any FM modelling and more consolidated data is needed.

For me 8sec at very high speeds for fabric cover ailerons is - in the first instance - as good as any other value because I simply do not know what would be a realistic number. My guess is that it is anyhow difficult to tell. And more difficult to extrapolate from other types - even from those who also have fabric covered ailerons. There are too many factors entering into the equation to make a definitive statement on roll rate just by knowing the cover material. I think that the aileron distortions which are the cause for modified aileron sensitivity at high speed not only may worsen with fabric cover but also with sub optimal supporting structure. Rolling also means to modify air streams over the wing assymetrically and wing aerodynamic form may impact how effective ailerons are.

Another matter is how much force the pilot can exercise upon the ailerons. Or vice versa how strong the aileron forces are that the pilot has to counter.

The complete graph showing the stick forces is even better! ;)

http://kurfurst.org/Tactical_trials/...s/image040.jpg

and also:

"The rolling ability of the enemy fighters (Spitfire, Hurricane, Curtiss) at high speeds is worse than that of the Bf 109. Quick changes of the trajectory along the vertical axis cause especially with the Spitfire load changes around the cranial axis, coming from high longitudinal thrust momemtum, and significantly disturb the aiming."

http://kurfurst.org/Tactical_trials/...g_Aug1940.html

Quote:

Originally Posted by Catseye (Post 417607)

I dunno, remember these speeds are mph not kph, 400mph is hauling butt in these 1940 models!

Actually seeing Banks graph shows 4secs for the Spit and about 4.5secs for the 109 in a 45° bank at 400 mph. For 90° you can double the figures. So it would be 8secs for the spit and 9 secs for the 109 at these high speeds.

Where does the graph come from? Is it original test data or someone who wanted to write a book to sell it?

The following graph is showing roll rate of the Spitfire Mark V, with fabric covered ailerons, via J. Smith -The Developement of the Spitfire and Seafire, Royal Aeronautical Society.

The Mark I and Mark IIs we have in the simulation had fabric covered ailerons, so roll rate should be identical. It appears our Spitfire I and II have the roll rates of the metal covered Spitfire's, which is incorrect, as none were fitted with metal ailerons until about May 1941.

Bearing in mind the figures are for a 50lbs stick force, how is it possible to reproduce these conditions in a simulator when there is no mechanical simulation? how is it possible to tell you are applying the equivalent of 50lbs on your gaming joysick? I would say 50 lbs in nowhwere near equivalent of a full deflection at the higher speeds which means being able to apply full deflection in the sim will give higher roll rates than the calibrated data.