Slingsby Kirby Kadet

Slingsby Kirby Kadet
Kirby Cadet TX.1 at the Yorkshire Air Museum
Type:	Glider
Design country:	Germany / Great Britain
Manufacturer:	Slingsby Sailplanes, Kirbymoorside
First flight:	January 11, 1936
Production time:	1936-1954
Number of pieces:	431 in total (254 built at Slingsby) + kits

The Slingsby Type 7 (T.7) Kirby Kadet is a single-seat glider made by the British manufacturer Slingsby Sailplanes, Kirbymoorside from the 1930s. In service with the Royal Air Force , it was called Cadet TX.1 . With various modifications, it remained in series production for over 10 years and with 431 units is the most popular glider in Great Britain. The name component Kirby originated from the place name Kirbymoorside in Yorkshire, where the company location from Scarborough had been moved. More recently the place name changed to Kirkbymoorside .

history

development

The designer of the Kadet was John Stanley Sproule, who began working for Slingsby in 1935. At that time, prospective pilots, who had their first flight experience with gliders like the pupil, continued their training with airplanes (in Germany called a training glider) like the examinee. Another aircraft for this purpose was the Hol's der Teufel, some of which flew in England in 1935. Based on the experience with these aircraft, Sproule designed an improved pattern in the fall and winter of 1935, borrowing from earlier Slingsby designs.

Flight testing

The first flights showed that the wing tips were not torsionally stiff enough and that a reversal of the aileron effect could occur. This phenomenon was not unknown in other lightweight aircraft of the time, for example the RRG Professor . With additional diagonal bracing elements in the wing, this problem could be solved. In addition, flow separation above the fuselage could lead to tail buffeting and stimulate the entire structure to produce harmonic oscillations , which the pilot perceived as very uncomfortable .

In April 1936, the first and second prototype, in which a Göttingen 426 profile was used for the first time, was extensively tested by members of the Midland Gliding Club in Long Mynd . The assessment was very positive for both aircraft, because of the lower stall speed of the machine equipped with the Göttingen profile, this was chosen as the basis for the series version. As a remedy for the tail buffeting, the same path was followed that Edmund Schneider had chosen in the case of the Grunau Baby. Slingsby changed the straight back of the fuselage behind the trailing edge of the wing in such a way that it was now curved downwards. The bow of the fuselage was also given an overall rounder appearance.

Series production and service in the Air Training Corps

Slingsby only introduced the hull changes described after the start of series production. Some of the 20 units delivered before the start of World War II already received these modifications. The height of the vertical stabilizer was also reduced a bit during production.

During the war, the Air Ministry came to the conclusion that the Kirby Kadet was used as a training aircraft for gliding. Engineers of the Royal Aircraft Establishment in Farnborough suggested some changes in the fuselage construction and the addition of a nose wheel. The use of a self-releasing Ottfur bow coupling for the winch launch was also planned. The designation at the Air Training Corps (ATC) of the RAF was Cadet TX Mk. 1 . Slingsby received an order for 200 copies, after which other companies such as Fox & Davis Ltd., Papworth Industries, Enham Industries and others manufactured the Cadet as licensees. The ATC program initially continued after the war, but was then severely scaled back. Only a few Cadets made it onto the civilian market, as the majority of the machines used at the ATC had to be written off as a result of the tough training operations. After the war, clubs therefore mainly ordered brand-new machines for training purposes. But there were also a number of kits that were sold. In June 1960, a redesigned Cadet made a long-distance flight of 212 km, which was the longest cross-country flight of the type at least until 1993.

construction

The wings of the Kadet had a rectangular floor plan and parallel double spars with internal bracing to absorb torsional forces. Sproule developed the profile himself. The leading edge of the wing was clad in plywood, but was not designed to absorb forces, it was only used for shaping. The rest of the area was covered with fabric. With the double tension struts on each side one avoided expensive and heavy wing fittings for the fuselage connection. The two wings butted together over the fuselage and were connected to the fuselage by means of two steel rods. The series aircraft no longer had a V-position , as was the case with the prototype.

The main ribs of the fuselage were extended upwards so that they could carry the wings in the form of a plywood-clad pylon. The tubular steel struts of the wings were connected to the lower corners of the ribs. The fuselage, which was entirely clad in plywood, had a straight stringer with a fabric covering in the upper area between the rear edge of the wing and the horizontal stabilizer to allow inspections. The bow shape was also based on the test item and Hol's der Teufel in that the bow was rounded in the top view, but straight and inclined backwards in the side view. The high rudder was aerodynamically balanced.

Technical specifications

Parameter	Data
crew	1
length	6.46 m (early), 6.36 m (main model)
Trunk width	0.56 m
span	11.70 m
Wing depth	1.38 m
Wing area	15.8 m²
Wing loading	155 N / m²
Wing extension	8.67
Empty mass	134.5 kg
Takeoff mass	232.7 kg

See also

• List of aircraft types

literature

• Martin Simons: Sling's Sailplanes, Part 7 . In: Airplane Monthly. February 1993, pp. 42-46.
• Martin Simons: Segelflugzeuge - 1920 to 1945 , Eqip Werbung & Verlag GmbH, 2001 (2nd edition 2005), ISBN 3-9806773-6-2 , p. 173 ff.

Web links

• Slingsby Guide, pp. 8-11
• Photo and short history (accessed September 22, 2015)

Individual evidence

1. ^ Günter Brinkmann, Hans Zacher: Die Evolution der Segelflugzeuge (Die deutsche Luftfahrt Volume 19) , Bernard & Graefe Verlag, 1992 (2nd edition 1999), p. 43