If a glider were to be designed for the Air Cadet requirement and
nothing else, it would need to be designed for easy and quick maintenance, and provide all the protection that modern gliders do. Composites have the advantage of being resistant to weather, fatigue and minor damage in a way that wood, fabric and sheet metal structures do not. The expense with composite repairs comes with the man hours required to restore the surface finish to 'as it left the mould' standard.
What is needed is a glider which provides performance equal to, or better than, the T21 and T31, with the durability and crashworthiness of a glass glider, whilst avoiding the need for multi-thousand pound repairs for relatively minor incidents. A broken canopy on one of our club's fibreglass gliders was £4000 to replace. The blow moulding was about £1K; however by the time the old canopy had been cut off the frame and the new one bonded on, filled, painted and the direct vision panel fitted, another £3K had gone.
A construction method which may offer the solution is to use folded honeycomb composite (Fibrelam) as on the Edgley Ea-9 Optimist. Expensive moulds are avoided, crash deformation can be predicted and if two dimensional canopy or simple screens used, the costs of most common repairs are kept sensible.
http://www.retroplane.net/forum/files/optimist_195.pdf
https://www.flightglobal.com/FlightP...20-%202845.PDF
If Edgley hadn't gone out of business, it appears Fibrelam training glider may have actually been built:
https://www.faulkes.com/edgley-sailplanes-ltd