Spitfire MK VII propeller blade. Part 1: Modelling


Thought it would be fun to replace ceiling fan blades in our lounge with blades from a Spitfire. The Spitfire was an iconic British WWII plane akin to USAF Mustang. Both planes used the same engine Rolls Royce Merlin engine. The plan is to 3D print them albeit scaled down a little. These means modelling them in 3D.

Blueprints

Some old ”original” blueprints can be found on the Horden Richmond Aircraft website. Amongst other things they sell a framed print of the blueprint for a blade (drawing HR 633A). One can find a fairly hi-defition image of blueprint by going under the bonnet of the website.

Material

According to the Horden Richmond’s about page, the original company’s founders invented the resin-impregnated wood material, Hydulignum,¬†from which some Spitfire prop blades were made. Horden Richmond manufactured blades for the Spitfire and other war planes as a part of the Ally war effort.

Hydulignum, the material from which main body was made, and Crystofin, some sort of resin/fabric coating are both referred to on the blueprint. I did do a little digging on Hydulignum but it turns out to be quite a rabbit warren – various manufacturers made versions of the prop blades using proprietary ‘composite timber’ formulations. Early blades were aluminium allay, until shortages made wood more favourable.

I have no intention of recreating blades out of Hydulignum, or timber, for the moment. I’ll print them from plastic and dress them up to look like the origins.

Modelling

Fusion 360 archive file d/l on link below…

Rhino3D & Grasshopper

Modelling started in Rhino3D (actually Grasshopper) to reconstruct the from the blueprint using Rhino’s surfacing prowess. 99% of information needed is there on the blueprint, with only the blade tip and base a little underdefined.

Autodesk Fusion 360

Completing the whole model in Rhino ended up a bit of a chore (struggled to make model a watertight solid) so i finished up working in Fusion360. Missing information was sculpted ‘by eye’, based on some old photos I found.

A real antique propeller blade