In the UK, the Bristol "Laboratory" was built to study the drag of different cowlings for radial engines and the Parnall Parasol to measure the forces acting on wings of different section in flight.
The two main problems facing Parnall when given an Air Ministry contract to produce such an aircraft were to ensure that, so far as possible the behaviour of the wing was unaffected by interference with the flow over the fuselage or by prop wash, and to devise a way of measuring lift and drag forces whilst in flight.
The V-struts were hinged top and bottom, allowing the wing to move parallel to the horizontal frame under aerodynamic loads.
The force was measured by a dynamometer ahead of the front cockpit, via a linkage which ran down and forward from the wing at an angle of about 22°, then turned back to the instrument via a crank.
The quite slender fuselage was a mixture of steel tubes and spruce,[6] square sided aft of the cockpits and rounded forwards.
The supercharged 226 hp (169 kW) Armstrong Siddeley Lynx radial engine was smoothly cowled but with its cylinder heads exposed.
The undercarriage was the divided type with wide splayed main oleo legs joining the fuselage below and between the wing struts.
There were bracing struts forward to the engine bulkhead and the axles sloped inwards and upwards to a post below the fuselage, all rather like a strengthened version of the on the Parnall Elf.
At one stage the upper surface of its wing was covered in wool tufts and a camera was fitted to a high pylon just in front of the tail to record their behaviour.