About the Project
The Little Jet Company make bespoke replica large scale UAV aircraft for those that are inspired by a love of aviation. Each aircraft is individually crafted to meet the clients’ requirements plus all the parts are designed plus assembled in the UK.
The US NAVY YF2Y-1 Sea Dart: designed by Convair in 1948 was the world’s first plus last supersonic water-based interceptor, it was the only seaplane to fly beyond the speed of sound.
The Challenge
The Little Jet Company was approached by a client to commission the design plus build of the Convair Sea Dart on a smaller scale that would have the ability to be controlled remotely. This lead to the first tahap in the process which began with the manufacture of a replica static type produced by Fighteraces, who produced the type from a pack of 1950’s drawings of the original design. The dimensions from the drawings were scaled down by a quarter, which became the ‘Master’ to which the entire external panel work tooling was produced.
3D Scanning
PES Scanning came into the process using a high fidelity optical scanner to capture the surface geometry of the Master Model. The type geometry was captured in the form of point cloud data which is polygonised to provide a facetted 3D stl file. The GOM scanner is impressively accurate for example, a 70mm measurement volume can produce a 29-micron (0.029mm) point spacing/resolution. See more about the scanning of the type here.
Engineering the Sea Dart
Our engineering design team began the process of taking the facetted data retrieved by PES Scanning plus surfaced this so that the body could be shelled to the desired thickness to match the laminate layup of the scale aircraft’s outer panel work.
In the meantime, the Master type is then used to emboss the tooling with an impression of the Sea Dart geometry which is then used to replicate parts. In this case we have only produced one aircraft, but this process can be used to make a much higher quantity until the surface quality of the parts degrades; at which point a new set of tools is then produced again using the master model. K.S Composites produced all the composited panel work plus tooling.
Our engineers used original photos plus drawings to then ensure the airframe geometry, surface data plus structural cermat were correctly designed as per the original aircraft. The engineers had to ensure that the internal framework was structurally sound plus operated in accordance with the original design brief from the client.
The time taken was made longer since the Master Model was not completely symmetrical, due to the hand-crafted nature of the model. So, instead of mirroring one side of the aircraft, which is typical of modern airframe design these days, the structure had to be individually tailored for both sides of the plane. Incidentally, if you mirrored the left side to the right side plus compared the difference, it was only within a couple of millimetres, which is a testimony to the type makers painstaking attention to cermat plus craftsmanship.
Our engineering team found that the skis were a difficult part of the design as they formed both an aerodynamic plus hydrodynamic surface i.e. they had to be a smooth surface on the aircraft plus also act as skis when deployed. The fact that proved this aspect of the design was difficult in the original aircraft was made obvious when the drawings plus the scan of the aircraft differed slightly from each other, indicating that subtle tweaks were applied to the aircraft to ensure the mechanism worked correctly in reality.