Phil Irving's design notebooks......four small books that PEI recorded much of his work at Velocettes and Vincents...

I visited Phil Irving on several occasions when I had time whilst in the Melbourne area in Victoria, Australia years back and on one occasion when I was questioning him over the bore and stroke dimensions on the Stuart Waycott "600cc" ISDT Velocette outfit's engine.... it was 85mm bore and 105mm stroke out of interest and I'm assembling a blog on this machine now.....he produced four small black notebooks that were used by him when he was in the UK from around 1931 to the late 1940's and we looked in one for these dimensions.
They contained fascinating design calculations, power information etc for the LE Velocette that he did some initial work on, the Model O road twin of the Roarer, the ISDT outfit as mentioned and a general notebook with Military MAC information as well as JAP engined specials....
All fascinating stuff.
I've them on loan again and doing a full scan of their contents into digital form and will share some of the pages with you over this and future blogs....
This blog features items from around 1931 when he left Velocette and went to London to assist several Australian with JAP engined racers and record breakers...in particular the attempt in Hungary on the world Land Speed Record using a Brough Superior with a 996cc V-Twin JAP called "Leaping Lena" ridden by Aussie Arthur Simcock.
I've scanned a section from Phil's Autobiography, pages 172-177 and pages from his little notebooks referring to this and to a 250cc JAP engined racer that was used in the IOM TT in 1931.
Left click on the images to enlarge...