Alliot Verdon Roe designed and built the first all British designed and built aircraft to fly in Britain on 8th July 1908 at Brooklands. The next year he built his first triplane which was constructed mainly of deal and covered in oiled paper. It weighed 250lbs. It had triplane wings and tailplane and was grossly underpowered by a 9hp JAP engine driving a 9ft, 4 blade propeller via a belt reduction. Its longest flight was 900ft at an average height of 10ft. The original aircraft is in the London Science Museum.
A.V. Roe designed and built several other versions of the triplane. The final version was a Triplane 4, completed in September 1910 powered by a 35hp, 4 cylinder, water cooled, Green engine. This was used almost exclusively for instructional work at the Avro flying School at Brooklands. It crashed many times. Howard Pixton crashed it twice into the sewage farm lake at the rear of the banked racing car circuit and became known as “The King of the Sewage Farm”.
The initial decision to build a triplane was made in February 1990. It was thought that this was going to be a difficult aircraft to fly and hopefully a large aeroplane would give a lower wing loading and hence ease the problems.
The design of the model was started by studying the replica from the film ‘Those Magnificent Men and their Flying Machines’ which is in the Shuttleworth Museum and still flys (when the weather conditions are good).
The majority of the model is constructed using spruce glued with exterior white wood glue.
The model’s top and middle wings feature wing warping. It was decided to build the three wings as a single unit to reduce assembly time and rigging.
The ribs are balsa with 1/16″ spruce upper and lower capstrips.
When the full-size replica was first flown and turned, the rear fuselage would twist in the opposite direction to the required turn reducing its effect and making the circuit diameter several miles. This was fixed by adding bracing wires from the wing to the rear fuselage. These wires have been fitted to the model.
The bottom longeron was laminated from two pieces of wood. The curved front end was produced by cutting 1/16″ slits in the wood and gluing in a jig with additional filler strips. The top longerons had to be slit horizontally and vertically because of the double curvature at the nose.
The undercarriage skids are 4.5ft long, each laminated from seven pieces of 3/16″ x 11/4″ spruce strips. These are very strong yet only weigh 1 1/2lbs each.
This photograph shows the construction. It is held together with string and dummy wood undercarriage supports.
The wing struts are 1/2" diameter 16 gauge dural rod. To achieve the ‘teardrop’ shape a 3/16" dowel was taped to the rear side. The rigging wires are 1.5mm, 49 strand stainless steel. These were attached to the wings using homemade stainless steel turnbuckles, about 200 in total. There are also over 300 stainless steel wing and fuselage brackets which are fitted with 3mm Allen bolts.
The wings were covered in ‘Polytex’. During this Ian needed assistance to extract himself from the rigging wires! The covering was applied in the dining room in December 1991. Ian’s wife, Doreen, said that he had to either move the wings to the garage to make room for the Christmas tree or she would decorate the wings with toys, tinsel and lights! He did as instructed, but a few days after Christmas they were back in the house.
Rolling the aircraft is achieved with wing warping. Two 24kg Multiplex Jumbo servos are used. The elevators are moved by two 1/4 scale Futaba servos. The rudder servo is a 20kg Multiplex Jumbo.
The tail is 4 1/2ft long and wide. The spars and tips are tapered with thin ply gussets. A cross was made from 1/2" and 3/8" tube to support the rudder, elevators and tailskid. Hinges were made from stainless steel straps wrapped over the wood. PTFE 1/64" bearing strips are sandwiched between the wood and each strap. The large rudder and elevator horns were made from thin wall stainless steel tube which was squashed into an oval shape.
The covering was completed using dope and coloured varnishes.
The engine is a 212cc German ‘Solo’ single cylinder petrol engine. It weighs 17lb without the silencer. It took several attempts to reduce the vibration. The engine is mounted on dural bars which are attached to laminated engine bearers which run from the nose to the cockpit via six Radio Spares "Isolator" rubber mounts. The silencer was made from 22 gauge stainless steel shaped to fit behind the cylinder.
The only lead used to balance the model was a 3/8" thick, 7lb lead bulkhead and 1lb of lead taped on each skid.
Ian’s plan was that the model would be transported in his caravan. Measurements showed it would fit, but it wouldn’t! Ian took the wardrobe out of the caravan to enable the model to be transported for test flights. Doreen commented "Besides having nothing to wear, I have nowhere to put it!" Later, a smaller version of the wardrobe was fitted!
It takes about one hour to assembly the plane.
After some taxing trials the new plane was pointed into wing and after a few seconds lifted off. The climb rate was poor, it felt nose heavy and the left wing hung down. The first turn left was started with the rudder and balanced using the wing warping. After it had tilted only a few degrees it went into a fast left side slip. The tail dropped and the fuselage yawed to the right, rapidly losing height. It was on the way to a crash! With some anguish and rapid "stick work" the plane was recovered. A couple of large circuits were completed before the first landing back into wind.
For the next flight the lead was removed from the skids, moving the centre of gravity slightly rear. Turns were still difficult. Four flights were made, each time moving the centre of gravity slightly rearwards. Ian was becoming accustomed to the Avro’s flight characteristics: "horrible". With a new propeller in the hope of gaining more thrust, the model was taken to France for the famous model show at La Ferte-Alais. The aeroplane’s characteristics again exhibited themselves. In the qualification flights it struggled in strong turbulence from some trees.
It was however flown twice during the show and awarded the "Best Early Aircraft" trophy.
Once back in the UK, Ian searched reference books for help to improve the flight characteristics. He discovered that the full-size had a poor climb rate, lacked stability and was prone to side slipping. It also suffered many crashes! The video of the "Magnificent Men in their Flying Machines" showed that for the flying shots, the fuselage between the cockpit and leading edge of the tailplane had laced on covering. Studies of the replica flown without the covering showed very flat and wide turns.
So fuselage covering was added to the model and a new propeller carved which was slightly narrower and thinner and produced an estimated 20% more thrust. The flight characteristics were then much improved and the side slipping tendencies reduced.
Recent improvements have included the use of a much lighter pilot, more forward position of the batteries, the removal of lead and a small amount additional incidence on the port wing panels. A 38" x 9.5" propeller is now used. These changes improved the aircraft’s flying characteristics.
It is still not an easy aeroplane to fly, but is now more predictable and looks majestic in the sky.
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