Speaker Alasdair MacInnes

Stirling Rotary meeting 20th. February 2015

President David Paterson welcomed members, together with the two speakers, Alasdair MacInnes and Ian Sutherland, Chairman and Secretary respectfully of Alloa and District Radio Flying Club.  The duo delivered a fascinating presentation on the activities of the club and also brought along some model planes and engines, to illustrate the talk. 

The club was formed in 1970, with just 10 members.  In these days, radio control was in its infancy and fly-aways were common.  Nowadays, equipment has advanced by leaps and bounds, being computerised and generally reliable.  Membership now stands at 25-30 and includes affiliation to the Scottish Aeromodellers Association, which is the governing body for modelling in Scotland.  This association, in conjunction with the Civil Aviation Authority, sets out rules and safety regulations, with which the club complies.

Principles of flight, which apply equally to model and full size aircraft are based on the 4 forces of drag, thrust, lift and gravity. Any alteration in one affects the others so, for instance, if thrust is increased, the plane will start to climb without necessarily gaining airspeed or pitching up the nose. By contrast, during landing, speed of descent is also controlled by adjusting thrust, to obtain the required sink rate.  When it comes to turning, moving the rudder alone from side to side would simply result in the aircraft skidding and not necessarily changing direction, unless the ailerons were used to bank the aircraft and assist the turn.  Elevators are also used in a turn to avoid any tendency for the aircraft to descend, due to reduced lift compared with that offered in straight and level flight.  The conclusion to be drawn from all this is that good co-ordination, on the part of the operator, is a vital necessity.

As regards propulsion, this can take the form of an IC (Internal Combustion) engine, a petrol engine which usually has no spark plug or ignition system.  Instead, for simplicity, a glow plug ignites the petrol/air mixture when the piston reaches the top of the compression stroke.  The rise of lithium ion batteries, however, has caused a strong movement towards electric power.  Previously, battery weight would have been prohibitive, but now Li-Ion packs with the same output as a car battery can fit into a jacket pocket, whilst the motors themselves are much simpler and less temperamental than petrol engines.

The club is keen to encourage young members and, to this end, offers appropriate training.  It has a close relationship with local RAF Air Training Cadets and provides dual control equipment, so an experienced pilot can take over if the situation looks dire.

Vote of Thanks was offered by Robin Sutton and well supported.  This weeks Speakers Host is Ranald Ross-Watt, with Visitors Host Derek Anderson.  Stirling Rotary can be contacted at www.stirling.rotary1010.org.

Ranald Ross-Watt
Communications Convener