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Thread: Spitfire roll rate | Forums

  1. #1
    XyZspineZyX
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    Message Edited on 10/03/0312:02PM by Vo101_Isegrim
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  2. #2
    XyZspineZyX
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    Message Edited on 10/03/0312:02PM by Vo101_Isegrim
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  3. #3
    XyZspineZyX
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    From :

    "Measurements of the flying qualities of a Supermarine Sptitife VA airplane." NACA Advanced Confidental Report, by William H. Phillips and Joseph R. Vensel.

    The tests were conducted at Langley field, Va., during the period from December 30, 1941 to January 29, 1942. Sixteen flights and apprx. 18 hours flying time were required to complete the tests.

    [...]

    Desription of the the Supermarine Spitfire airplane

    Name and Type : Supermarine Spitfire VA (Air Mininstry No. W3119).
    Engine : R-R Merlin XLV
    Weight, empty : 4960 lbs
    Normal gross weight : 6237 lbs
    Weight as flown for tests : 6184 lbs

    Ailerons (metal-covered)
    Lenght (each) : 6 feet, 10 1/2 inches
    Area (total area, each) : 9.45 sq. feet
    Balance area (each) : 2.45 square feet

    [...]

    A stick force of 2 lbs to the right and 3 lbs to the left was required to overcome aileron friction.

    [...]

    Lateral Stability and Control

    Aileron-control characteristics : The effectiveness of the ailerons of the Supermarine Spitfire airplane was determined by recording the rolling velocity produced by abrubtly deflecting the ailerons at various speeds. The aileron angles and stick forces were measured. It should be noted that the airplane tested was equipeed with metal covered ailerons.

    [...]

    The ailerons were sufficiently effective at low speeds, and were relatively light at small deflections in high speed flight. The forces required to obtain high rolling velocities in high-speed flight were considered excessive.
    With a stick force of 30 lbs, full deflection of the ailerons could be obtained at speeds lower than 110 miles per hour. A value of pb/2V of 0.09 radian in left rolls and 0.08 radian in right rolls were obtained with full deflection.

    Rolling velocity (at 6000 ft altitude) of about 59 degrees per second could be obtained with 30 lbs stick force at 230 miles per hour indicated speed.

    The ailerons were relatively light for small deflections, but the slope of the curve of stick force against deflection increased progressively with deflection, so that about five times as much force was required to fully deflect the ailerons as was needed to reach one-half of the maximum travel. The effectiveness of the ailerons increased almost linearly with deflection all the way up to maximum position. The value of pb/2V obtained for a given ailerons deflection was nearly the same in speeds and conditions tested. It may be concluded, therefore, that there was very little reduction in aileron effectiveness either by separation of flow near minimum speeds or by wing twist at high speed.

    Fig 27 shows the aileron deflection, stick force, and helix angle obtained in a series of roll at various speeds intended to represent the maximum rolling velocity that could be readily obtained.

    The pilot was able to exert a maximum of about 40 lbs on the stick. With this force, full deflection could be attained only up to about 130 miles per hour. Beyond this speed, the rapid increase in stick force near maximum deflection prevented full motion of the control stick. Only one-half of the available deflection was reached with a 40 lbs stick force at 300 miles per hour, with the result that the pb/2V obtainable at this speed was reduced to 0.04 radian, or one-half that reached at low speeds.

    Another method of presenting the results of the aileron-roll measurements is that given in figure 28, where the force for different rolling velocities is plotted as a function of speed. The relatively light forces required to reach small rolling velocities are readily seen from this figure. The excessive forces required to reach high rolling velocities and the impossibility of obtaining maximum aileron deflection much above 140 miles per hour are also illustrated.


    From :

    STABILITY AND CONTROL SUB-COMMITEE. AERONAUTICAL RESEARCH COMMITEE
    Comparision of aileron control charactheristics as determined in Flight Tests of P-36, P-40, 'Spitfire' and 'Hurricane' Pursuit airplanes.

    By William H. Philps. N.A.C.A. Confidental Bulletin. 16th November, 1942

    [..]

    The aileron effectiveness of the various airplanes is compared in the following table on the basis of the response obtained with stick forces of 30 and 5 pounds. A force of 30 lbs is somewhat less than the greatest stick force exerted by the pilot. Repeated flight measurements have shown, however, that this forcer is a reasonable upper limit for manouvering at high speeds. A comparision at a stick force of 5 lbs are also included to bring out a rather interesting fact regarding the order of merit of aileron effectiveness for the various airplanes when very light forces are used :

    Rolling velocities obtained with 30 lbs stick force at 230 mph indicated airspeed at 10 000 ft. (deg/sec)

    P-36 : 43
    P-40 : 90
    Hurricane : 64
    Spitfire : 63

    Rolling velocities obtained with 5 lbs stick force at 230 mph indicated airspeed at 10 000 ft (deg/sec)

    P-36 : 9
    P-40 : 8
    Hurricane : 19
    Spitfire : 15



    A further comparision of the aileron performance of the four airplanes is given in figure 2, which shows how the control force characteristics influence the rolling velocities obtained through the speed range.









    'Only a dead Indianer is a good Indianer!'

    Vezérünk a Bátorság, K*sérµnk a Szerencse!
    (Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

    Flight tests and other aviation performance data: http://www.pbase.com/isegrim
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  4. #4
    XyZspineZyX
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    That's for the .Va version and it really does not look too good. Even the Hurri rolls better. Don't you happen to have similar comparison for the later models as well? I mean for the Mk.IX, XIV? Clipped and non-clipped wings?
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  5. #5
    XyZspineZyX
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    Why don't you post the graph from NACA Report 868 Issy?

    Here are some results:

    Spitfire, normal wing:

    160mph(IAS) > 87 degrees/sec
    210mph > 105 degrees/sec
    400mph > 44 degrees/sec

    Spitfire, clipped wing:

    160mph(IAS) > 128 degrees/sec
    210mph > 150 degrees/sec
    400mph > 72 degrees/sec

    For the Fw190(for comparison)

    160mph(IAS) > 114 degrees/sec
    210mph > 137 degrees/sec
    400mph > 78 degrees/sec






    "Only a dead 'chamber pot' is a good 'chamber pot'!"


    Message Edited on 10/03/0309:38AM by MiloMorai
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  6. #6
    XyZspineZyX
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    I know where this is going. But before all that gets started I just wanted to point out the P-40s curve. Dang! That thing rolls like crazy!
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  7. #7
    XyZspineZyX
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    MiloMorai wrote:
    - Why don't you post the graph from NACA Report 868
    - Issy?
    -
    - Here are some results:
    -
    - Spitfire, normal wing:
    -
    - 160mph(IAS) > 87 degrees/sec
    - 210mph > 105 degrees/sec
    - 400mph > 44 degrees/sec
    -
    - Spitfire, clipped wing:
    -
    - 160mph(IAS) > 128 degrees/sec
    - 210mph > 150 degrees/sec
    - 400mph > 72 degrees/sec
    -
    - For the Fw190(for comparison)
    -
    - 160mph(IAS) > 114 degrees/sec
    - 210mph > 137 degrees/sec
    - 400mph > 78 degrees/sec


    Why don't you post the test in which those roll rates were obtained. Nobody is interested in roll rates for modified planes. NACA modified the planes tested a lot, for research purposes. Post the test Milo, to see the modifications.


    The test Isegrim posted is for a combat ready aircraft. Also I posted in the other thread a similar NACA test, giving the same roll rate for Spitfire: max roll rate 60deg/sec at 230mph.


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  8. #8
    XyZspineZyX
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    I know this will probably come as a major shock to you, but I agree with what you have pointed out in your post. The Spitfire was a mediocre roller, particularly the earlier models. Thanks for posting a decorous and well supported argument.



    Blutarski
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  9. #9
    XyZspineZyX
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    Huckebein_FW wrote:

    -
    - Post the test
    - Milo, to see the modifications.
    -
    -


    Why don't you post the tests done Huckie? That way you could 'put me in my place' without your usual gum flappin.[img]/i/smilies/16x16_smiley-happy.gif[/img]








    "Only a dead 'chamber pot' is a good 'chamber pot'!"
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  10. #10
    XyZspineZyX
    Guest
    MiloMorai wrote:
    - Why don't you post the graph from NACA Report 868
    - Issy?
    -
    - Here are some results:
    -
    - Spitfire, normal wing:
    -
    - 160mph(IAS) > 87 degrees/sec
    - 210mph > 105 degrees/sec
    - 400mph > 44 degrees/sec
    -
    - Spitfire, clipped wing:
    -
    - 160mph(IAS) > 128 degrees/sec
    - 210mph > 150 degrees/sec
    - 400mph > 72 degrees/sec


    Yep, CALCULATED results from the Brits, which is damn obvious from the fact they are giving STRAIGHT roll curves up to 200mph at 50lbs (note that NACA`s engineers were unalbe to deflect the ailrons further than 130 mph, and the cramped canopy enable no more than 40 lbs stickforce). In additition, they didn`t took into account the wing twist - which decreased roll rate by 60% on the Spitifre (only about 35% on the P-47) at speeds, if you read the FULL report... They not even specify exact model... LOL!


    On the other hand, we have the testimony`s of REAL Spitfire pilots, like :


    This if form Alex Heshaw, the Chief pilot of the Castle Bromwhich Spitfire plant. He basically flew hundreds of Spitfires after they left the factory and were tested for airworthyness.


    "I loved the Spit, every Marks of it. But I must admit, that altough later Marks were much faster, they were also progressively inferior to previous Marks in manouveribility. When we checked how a Spit behaves during roll, we counted how many complete rolls we could do under a given time. With the Mark II and V, we did 2 1/2 rolls, but the Mark IX was heavier, and only capable of 1 1/2 rolls. The later, more heavier versions could do even less. Designing an aircraft is about finding balance. It`s hardly possible to improve performance without degrading other properties of the aircraft. "


    And this from Jeff Ethell:

    "The elevator is very light, while the rudder is stiff and the ailerons even more so. Every Spitfire I have flown take more muscle to roll than most other fighters. As speed increases, both rudder and ailerons get heavier, creating a curious mismatch at high speeds... on has to handle the almost oversensitive elevators with a light fingertip touch while arm-wrestling the stiff ailerons."



    And one more word: the NACA report I have shown is for an early MkVA, probably the best rolling of all Spitfires. It`s from the first batch of 78 planes, which still had 8 MGs, but already had the metal ailerons. All later MkVs had Hispano cannons installed in the wings, which decreased roll rate further because of the weight in the wings, and later models, as weight increased (to over 9000 lbs by 1945, 50% more than MkV), roll rate and manouveribilty decreased further.




    'Only a dead Indianer is a good Indianer!'

    Vezérünk a Bátorság, K*sérµnk a Szerencse!
    (Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

    Flight tests and other aviation performance data: http://www.pbase.com/isegrim
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