The Skylark Sounding Rocket

SKYLARK originated in 1955 when the Royal Society embarked on a programme of upper atmosphere research associated with the International Geophysical Year of 1957/58. Initially the project called for an unguided, fin-stabilized vehicle capable of lifting a 45kg scientific payload to an altitude of around 100km. By collaboration with the royal aircraft establishment (RAE) at Farnborough this requirement progressed quickly to the design and construction of the first SKYLARK in 1956. At the same time, production of a suitable solid propellant motor was undertaken by the Rocket propulsion establishment (RPE) at Westcott and the Banwell division of Bristol aircraft Ltd. Given the name Raven - in keeping with RPE's ornithological naming system- it was the biggest solid fuel rocket motor then in use, with a specific impulse of 1780 N s kg -1 (sea level) and a burning time of 30 seconds.

Shown left is the Skylark rocket in the foyer of the Physics and Astronomy building at the University of Leicester.

A 30 metre gimbal mounted launch tower made from bailey bridge panels was also designed by the RAE team and was constructed by the Royal Ordnance factory at Woolwich. The complete launcher was erected at the Woomera (South Australia) rocket range by May 1956 and the first SKYLARK - a technological vehicle - was launched on 13 th February 1957. After a further vehicle proving flight, the first scientific experiments were flown in SL 03 in July 1957; these were followed by a series of launches associated with the 1957/58 international geophysical year.

SKYLARK's performance was greatly enhanced in 1960 by the addition of a booster stage (Cuckoo) burning for 4 seconds, giving 80 kN thrust and adding about 40% to the peak height for a given payload mass. Later additions to the SKYLARK motor family were the Goldfinch booster and Raven XI, which when used together gave an apogee of over 500 km for a payload of 100 kg mass.

Another important SKYLARK development was the introduction of a 3-axis stabilized attitude control unit (ACU) developed jointly by RAE and Elliot Automation Ltd., Frimley. The ACU was initially designed as a sun-pointing unit but later versions were available with sun, moon or star pointing sensors. After August 1964, many attitude controlled SkylarK s were launched, gathering much new information about the nature of the solar disk and other Galactic phenomena. Over 300 SKYLARKs were launched for scientific research purposes, yielding a very noteworthy success record.

While SKYLARKs are still in use, their application to astronomical research in the UK came to an end in 1978. Leicester scientists continued their rocket work through collaboration in the NASA sounding rocket programme. These flights made use of the Astrobee-F, of similar capability to the SKYLARK, and the Canadian Black Brant Vc. By 1985, diminishing scientific returns from the short observation times available with sounding rockets no longer justified the costs and involvement in these missions ceased.

However, most recently, we have developed new, much more efficient instruments that allow us to obtain significant scientific results within the time allowed by a sounding rocket flight. After a gap of 15 years, we have twice flown the Joint Plasmadynamic Experiment (J-PEX), a high-resolution extreme ultraviolet spectrometer, on a Black Brant IX rocket. The Black Brant IX is a two-stage system comprising a Terrier booster and Vc upper stage, which allows our heavy telescope to reach an altitude of 280km.

Shown is a summary of SKYLARKs and other rockets used by the University of Leicester X-ray and Observational Astronomy group in their research programme since 1961.

SKYLARK	Experiment	Stabilisation	Year
SL 37 SL 40 SL 42 SL 45 SL 46 SL 47 SL 83 SL 84 SL 85 SL 103 SL 104 SL 105 SL 106 SL 114 SL 115 SL 118 SL 119 SL 126 SL 127 SL 128 SL 129 SL 132 SL 133 SL 138 SL 301 SL 302 SL 303 SL 304 SL 305 SL 306 SL 307 SL 403 SL 404 SL 405 SL 406 SL 407 SL 408 SL 605 SL 723 SL 724 SL 802 SL 804 SL 812 SL 901 SL 904 SL 972 SL 1002 SL 1010	X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Telescope X-ray Camera X-ray Spectrometer X-ray Spectrometer X-ray Spectrometer X-ray Spectrometer X-ray Camera X-ray Camera X-ray Spectrometer X-ray Spectrometer First X-ray Sky Survey First X-ray Sky Survey X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Camera X-ray Spectograph X-ray Spectograph X-ray Spectograph X-ray Bragg Crystal Spectrometer X-ray Bragg Crystal Spectrometer X-ray Pinhole Camera X-ray Pinhole Camera Extra Galactic Survey of M87 X-ray Pinhole Camera X-ray Pinhole Camera X-ray Pinhole Camera X-ray Pinhole Camera X-ray Pinhole Camera Bragg Crystal Spectrometer Large Area Sky Survey Large Area Sky Survey Modulation Collimator Detector Bragg Crystal Spectrometer Survey of Norma X-1 & Cen X-3 Bragg Crystal Spectrometer Background Survey Large Area Sky Survey Lunar occultation of GX3+1 Low energy survey	Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Unstabilised Sun Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Moon Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Sun Pointing Unstabilised Unstabilised Sun Pointing Sun Pointing Star Pointing Sun & Sco X-1 Pointing Sun Pointing Spin Stabilised Sun & Sco X-1 Pointing Sun Pointing	1961 1961 1961 1962 1963 1964 1961 1963 1963 1963 1963 1965 1965 1962 1963 1967 1967 1963 1963 1964 1964 1964 1964 1964 1964 1964 1965 1966 1967 1965 1966 1968 1969 1966 1966 1967 1968 1969 1968 1968 1970 1970 1971 1970 1970 1970 1971 1973

SKYLARK	Experiment	Stabilisation	Year
SL 1011 SL 1101 SL 1105 SL 1112 SL 1202 SL 1206 SL 1304 SL 1306 SL 1611	Modulation Collimator Cir X-1 & Cen X-3 Bragg Crystal Spectrometer Low energy mapping of Vela Low energy interstellar gas abundance Lunar occultation of GX5-1 Bragg Crystal Spectrometer Lunar occultation of Crab Nebula Very large area mapping of Cyg X-1 Dust Halo 2-D imaging (cancelled)	Star Pointing Sun Pointing Magnetic & Moon Pointing Star pointing Sun pointing Sun pointing Sun pointing Sun pointing Inertial Platform	1973 1971 1975 1975 1972 1973 1974 1976 1978

ESA Payloads

S26 S41 S55 S69 S89

X-ray Spectroscopy Bragg Crystal Spectrometer Bragg Crystal Spectrometer Bragg Crystal Spectrometer Bragg Crystal Spectrometer

Unstabilised Sun pointing Sun & Sco X-1 pointing Sun pointing Sun pointing

1967 1967 1971 1970 1972

NASA Payloads

Astrobee-F Astrobee-F 25.040 A'bee-F 21.069 BB Vc 21.070 BB Vc 36.162 BB IX 36.195 BB IX

Imaging X-ray Telescope (Cygnus Loop) Imaging X-ray Telescope (Puppis A + Crab + IC433) Wide Field Ultrasoft X-ray Camera Wide Field Ultrasoft X-ray Camera Wide Field Ultrasoft X-ray Camera J-PEX High Resolution EUV Spectrometer J-PEX High Resolution EUV Spectrometer

3 axis stabilised 3 axis stabilised 3 axis stabilised 3 axis stabilised 3 axis stabilised 3 axis stabilised 3 axis stabilised

1977 1978 1981 1982 1985 2000 2001