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LeadingEdge Flaps and Variable Camber

LeadingEdge Flaps and Variable Camber RESEARCH Leading-Edge Flaps and use of trailing edge flaps. The report concludes-' 'It would appear that on the symmetrical thin Variable Camber wing a big advantage can be gained by using the small-chord slat as a turned-down nose to give the equivalent of camber. This has the dis­ Notes on Some Research Carried Out since 1945 advantage of moving the no-lift angle to a more positive value, and so decreasing the lift at a given prc-stall incidence'. It would also be a MON G the interesting features of the simpler arrangement mechanically. Handlcy Page Victor revealed in the official Further research on the use of leading-edge de­ photographs are what appear to be leading- vices, on swept wings3, was carried out later in edge flaps of considerable span. It can be seen the same year, this time on a model of a complete (FIG. 1) that the leading edge of the flap in the aircraft, which, it appears from a drawing in the down position docs not extend appreciably fur­ report, was the Supermarine 510. Apart from the ther forward than when it is in the normal flight investigation on trailing-edge flaps some indica­ position, as represented by the adjacent portion tion of the best length of slat or nose flap for of main wing structure. Thus it would seem that avoiding instability in the stall was sought. A true these surfaces are not slats (which provide a slot In the spring of 1948 work was done to dis­ nose flap (FIG 4) and the slat dipped to form a between themselves and the wing) and in con­ cover what modifications to the empirical rules sidering their purposes certain published reports developed for the design of Handlcy Page slats (it of research at the R.A.E. are interesting. is interesting to recall the historical interest of this In February 1945, wind-tunnel tests were car­ firm in leading edge devices) when applied to ried out on a sharp-nosed supersonic wing sec­ high-speed aerofoil sections2. Slats of 10, 20 and tion 7-5 per cent thick fitted with slat and flap.1 30 per cent chord were tried, and in the 10 per The mechanical difficulties in the way of achieving cent case it was discovered that the lift increased such a configuration on a thin wing led to the with slat dip, and with reduction of the gap, the consideration of an aerofoil hinged at two points, effect being greatest when the slat was so placed providing no leading edge slot, the result being as to be a leading edge flap (FIG. 3). A value of leading- and trailing-edge flaps which, in effect, introduced a considerable degree of camber to a flap were both investigated. It was found that section basically symmetrical (FIG. 2*). Results 50 per cent of the semi-span was the greatest of tests at the best settings showed an increase length of slat or nose flap which could be used in C/,max to 1 -84 (compared with 0 -65 for the basic without producing an unstable nose-up moment section and 2-02 for the best combination of slat at the stall. The results of dipping the slat to the and flap), the nose-flap angle being 40.degrees. nose-flap position were found to be less beneficial Thus this structurally more practical arrangement on lift than was found in rcf. 2; this may be con­ showed a considerable improvement in the rather nected with the sweepback and end effects. CLmax of 1 -355 was reached under these condi­ poor lift properties of a sharp-nosed supersonic On the basis of these reports it would seem, tions, compared with values of 1 -5 and 1 -8 re­ aerofoil. therefore, that the nose flaps on the portion of the spectively for the 20 and 30 per cent chord slats H. P. Victor's wing which has comparatively little in more conventional positions, and 0-9 for the sweep-back could considerably increase the maxi­ basic aerofoil. These values do not include the mum lift obtainable near the stall, and so improve performance at take-off and landing, and possibly also during climb. This is rendered the more nec­ essary by the choice, now universal for perform­ ance at high speed, of a thin symmetrical section with fairly small nose radius, as can be seen in FIG. 1. These surfaces have, as far as can be judged from the official photographs, a length of about 40 per cent of the semi-span of the wing, which is in accordance with the recommendations of ref. 3, bearing in mind the limited span of straight leading edge available on the crescent plan form. While it is possible that the two sec­ tions of the nose flaps are on portions of the wing having different angles of sweep-back it seems more likely that they are divided only for con­ venience and reliability. Industrial Matting 'The Way to Higher Output at Lower Cost' TRADE PUBLICATIONS RECEIVED [Nuway Manufacturing Co. Ltd., Coalport, Shrop­ [Intel (Caterers) Ltd., 2 Parkshot, Richmond, shire] Surrey] Service and Products [Edgar Vaughan & Co. Ltd., Lcggc Street, Birm­ Correct X-Ray Film Processing by Fully Automatic Silencing for Jet Test Houses ingham, 4] Control [Cementation (Muflelitc) Ltd., 39 Victoria Street, S.W.I] [Nuclconic and Radiological Developments Ltd., Automatic Controllers 22 Marshgatc Lane, E.I5] [Ncgrctti & Zambra Ltd., 122 Regent Street, W.l] Principal Products Elliott Microwave Instruments [Foster Transformers Ltd., South Wimbledon, The Direct Costs of 'Redux' Bonding in Aircraft [Elliott Brothers (London) Ltd., Century Works, S.W.19] {Bulletin No. 118, October 1952) Lcwisham, S.E.I3] [The Technical Service Department, Aero Research 'The Bee-Hive', Fall 1952 The de Havilland Enterprise—General Information Ltd., Duxford, Cambridge] [United Aircraft Corporation, East Hartford, Booklet, No. 12, August 1952 Conn., U.S.A.] Tungsten and Mercury Lighting Fittings [The de Havilland Aircraft Co. Ltd., Hatfield, Safety Booklet SBj\ [The Benjamin Electric Ltd., Brantwood Road, Herts] [Industrial Guarding Equipment Ltd., Mill Works, Tottenham, N.17] Accelerated Glue-Line Curing—Bulletin No. 119, Alvcchurch, Birmingham] November 1952 The Electric Tool User Lighting Fittings for 'Frenger' Warm Acoustic Ceiling [The Technical Service Department, Aero Research [Wolf Electric Tools Ltd., Pioneer Works, Hanger Industrial and Window Fluorescent Lighting Fittings Ltd., Duxford, Cambridge] Lane, W.5] Window and Display Lighting Fittings Spheroidal-Graphite Cast Iron Commercial Fluorescent Lighting Fittings Annual Report, 1952 [Courtney, Pope (Electrical) Ltd., Amhurst Park [The Mond Nickel Co. Ltd., Sunderland House, [The British Interplanetary Society, 12 Bcssborough Works, Tottenham, N.15] Curzon Street, W.l] Gardens, S.W.I] 54 A ircraft Engineering http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

LeadingEdge Flaps and Variable Camber

Aircraft Engineering and Aerospace Technology , Volume 25 (2): 1 – Feb 1, 1953

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb032261
Publisher site
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Abstract

RESEARCH Leading-Edge Flaps and use of trailing edge flaps. The report concludes-' 'It would appear that on the symmetrical thin Variable Camber wing a big advantage can be gained by using the small-chord slat as a turned-down nose to give the equivalent of camber. This has the dis­ Notes on Some Research Carried Out since 1945 advantage of moving the no-lift angle to a more positive value, and so decreasing the lift at a given prc-stall incidence'. It would also be a MON G the interesting features of the simpler arrangement mechanically. Handlcy Page Victor revealed in the official Further research on the use of leading-edge de­ photographs are what appear to be leading- vices, on swept wings3, was carried out later in edge flaps of considerable span. It can be seen the same year, this time on a model of a complete (FIG. 1) that the leading edge of the flap in the aircraft, which, it appears from a drawing in the down position docs not extend appreciably fur­ report, was the Supermarine 510. Apart from the ther forward than when it is in the normal flight investigation on trailing-edge flaps some indica­ position, as represented by the adjacent portion tion of the best length of slat or nose flap for of main wing structure. Thus it would seem that avoiding instability in the stall was sought. A true these surfaces are not slats (which provide a slot In the spring of 1948 work was done to dis­ nose flap (FIG 4) and the slat dipped to form a between themselves and the wing) and in con­ cover what modifications to the empirical rules sidering their purposes certain published reports developed for the design of Handlcy Page slats (it of research at the R.A.E. are interesting. is interesting to recall the historical interest of this In February 1945, wind-tunnel tests were car­ firm in leading edge devices) when applied to ried out on a sharp-nosed supersonic wing sec­ high-speed aerofoil sections2. Slats of 10, 20 and tion 7-5 per cent thick fitted with slat and flap.1 30 per cent chord were tried, and in the 10 per The mechanical difficulties in the way of achieving cent case it was discovered that the lift increased such a configuration on a thin wing led to the with slat dip, and with reduction of the gap, the consideration of an aerofoil hinged at two points, effect being greatest when the slat was so placed providing no leading edge slot, the result being as to be a leading edge flap (FIG. 3). A value of leading- and trailing-edge flaps which, in effect, introduced a considerable degree of camber to a flap were both investigated. It was found that section basically symmetrical (FIG. 2*). Results 50 per cent of the semi-span was the greatest of tests at the best settings showed an increase length of slat or nose flap which could be used in C/,max to 1 -84 (compared with 0 -65 for the basic without producing an unstable nose-up moment section and 2-02 for the best combination of slat at the stall. The results of dipping the slat to the and flap), the nose-flap angle being 40.degrees. nose-flap position were found to be less beneficial Thus this structurally more practical arrangement on lift than was found in rcf. 2; this may be con­ showed a considerable improvement in the rather nected with the sweepback and end effects. CLmax of 1 -355 was reached under these condi­ poor lift properties of a sharp-nosed supersonic On the basis of these reports it would seem, tions, compared with values of 1 -5 and 1 -8 re­ aerofoil. therefore, that the nose flaps on the portion of the spectively for the 20 and 30 per cent chord slats H. P. Victor's wing which has comparatively little in more conventional positions, and 0-9 for the sweep-back could considerably increase the maxi­ basic aerofoil. These values do not include the mum lift obtainable near the stall, and so improve performance at take-off and landing, and possibly also during climb. This is rendered the more nec­ essary by the choice, now universal for perform­ ance at high speed, of a thin symmetrical section with fairly small nose radius, as can be seen in FIG. 1. These surfaces have, as far as can be judged from the official photographs, a length of about 40 per cent of the semi-span of the wing, which is in accordance with the recommendations of ref. 3, bearing in mind the limited span of straight leading edge available on the crescent plan form. While it is possible that the two sec­ tions of the nose flaps are on portions of the wing having different angles of sweep-back it seems more likely that they are divided only for con­ venience and reliability. Industrial Matting 'The Way to Higher Output at Lower Cost' TRADE PUBLICATIONS RECEIVED [Nuway Manufacturing Co. Ltd., Coalport, Shrop­ [Intel (Caterers) Ltd., 2 Parkshot, Richmond, shire] Surrey] Service and Products [Edgar Vaughan & Co. Ltd., Lcggc Street, Birm­ Correct X-Ray Film Processing by Fully Automatic Silencing for Jet Test Houses ingham, 4] Control [Cementation (Muflelitc) Ltd., 39 Victoria Street, S.W.I] [Nuclconic and Radiological Developments Ltd., Automatic Controllers 22 Marshgatc Lane, E.I5] [Ncgrctti & Zambra Ltd., 122 Regent Street, W.l] Principal Products Elliott Microwave Instruments [Foster Transformers Ltd., South Wimbledon, The Direct Costs of 'Redux' Bonding in Aircraft [Elliott Brothers (London) Ltd., Century Works, S.W.19] {Bulletin No. 118, October 1952) Lcwisham, S.E.I3] [The Technical Service Department, Aero Research 'The Bee-Hive', Fall 1952 The de Havilland Enterprise—General Information Ltd., Duxford, Cambridge] [United Aircraft Corporation, East Hartford, Booklet, No. 12, August 1952 Conn., U.S.A.] Tungsten and Mercury Lighting Fittings [The de Havilland Aircraft Co. Ltd., Hatfield, Safety Booklet SBj\ [The Benjamin Electric Ltd., Brantwood Road, Herts] [Industrial Guarding Equipment Ltd., Mill Works, Tottenham, N.17] Accelerated Glue-Line Curing—Bulletin No. 119, Alvcchurch, Birmingham] November 1952 The Electric Tool User Lighting Fittings for 'Frenger' Warm Acoustic Ceiling [The Technical Service Department, Aero Research [Wolf Electric Tools Ltd., Pioneer Works, Hanger Industrial and Window Fluorescent Lighting Fittings Ltd., Duxford, Cambridge] Lane, W.5] Window and Display Lighting Fittings Spheroidal-Graphite Cast Iron Commercial Fluorescent Lighting Fittings Annual Report, 1952 [Courtney, Pope (Electrical) Ltd., Amhurst Park [The Mond Nickel Co. Ltd., Sunderland House, [The British Interplanetary Society, 12 Bcssborough Works, Tottenham, N.15] Curzon Street, W.l] Gardens, S.W.I] 54 A ircraft Engineering

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Feb 1, 1953

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