No . 138
The Trusty Servant
Afterburners and Aerodynamics :
Model Aeroplanes in the 1950s
Both the Trusty Servant and Trust e-Servant have published memories of Wykehamical gliding activities under the sometimes anxious eye of Bryan Thwaites ( C , 41-42 , CoRo 51-59 ). Stephen Winkworth ( C , 52-56 ), who went on to a career in aerodynamics provides his testimony . The series concludes with Bryan Thwaites himself under Vox Senum q . v :
Though I never had much joy from the Grasshopper I have many recollections of Bryan Thwaites ’ s other gliding group , who were sent to Lasham to be taught by that doyen of gliding , Derek Piggott .
Recently I built a 1 / 6 scale model of the glider in which some of us experienced our first solo flights : the Slingsby ‘ Cadet ’, to which I gave the spurious insignia BTDP – 56 ( Bryan Thwaites Derek Piggott 1956 … the year I went solo ). I still remember that first flight , and the prominent yellow ‘ tennis ball ’ knob , which had to be pulled at the right moment to release the towline . That flight sparked a lifelong interest in practical aerodynamics , including thirty years of paragliding .
Meeting Bryan years later rekindled our friendship and reminded me of his role in shaping my early interest in aerodynamics . Working on a David Attenborough film in 1984 , I consulted Bryan on the aerodynamics of pterodactyls , referring to his National Physical Laboratory papers from the 1940s . Bryan ’ s memory of me as a student surpassed mine — he recalled my correct answer to an unusual maths question : “ how would a three-toed sloth count ?” The idea of bases other than ten was much less familiar in those days .
Bryan also remembered a couple of projects I had thought up - aided and abetted by fellow Cookite , David du Boulay ( C , 52-57 ). As many schoolboys were then , we were fascinated by jetpropelled aircraft . We made small deltawing models that flew at impressively high speeds , thanks to an ingenious ‘ blow-back ’ flap , which kept the glider straight and level rather than flying in violent loops . We assumed that model gliders should be as light as possible but it took Bryan to explain that our models were far too light . “ No , no ,” he explained , “ mass is your motor ”, so we made models from plywood , liberally weighted with lumps of lead . The resulting models would sweep to impressive heights and descend at high speed in great swooping curves . We continued with our potentially dangerous fun , knowing that Thwaites would back us up , until we gradually lost interest and moved onto the next schoolboy fascination , the jet engine itself .
I had built a model of the Russian “ Lavochkin ” fighter from a “ Veron ” kit , powered by a small model diesel engine driving a fully-enclosed impeller , its thrust augmented by a duct . Would injecting fuel into the duct add an afterburner effect ?
The duct would have to be metal and the fuel pressurised for this concept
A Slingsby T21 being launched at Lasham airfield
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