Anyone who’s modelled a largish scale Spitfire or Hurricane must be familiar with the profusion of “W/T” stencils accompanied by indecipherable codes on practically any separable portion of the aircraft, but does anyone know what they’re for and especially what “W/T” stands for?
Michael
Hi MJH
I think there something to do with the substructure of dope & fabric A/C and stand for “wire tensioner”.
Regards Gary[8-]
It has to do with the metal structure being, I think, grounded, so at to not cause interference with the radio. At least it’s something like that, I just can’t recall the full story.
It can be seen on many fabric parts it is true, but it’s also seen on metal panels, especially on the Spitfire.
I had a feeling it might be related to the aircraft’s radio and could stand for “Wireless/Transmitter”, the early voice radios were decidedly tempermental and easily disturbed so there may be a point there, but I can’t see the connection. And what about the numbers?
Michael
It does stand for wireless transmitter, and has to do with the fact that all moving surfaces have to be electrically grounded to each other, “bonded” is the proper term, because different surfaces will build up different electrostatic charges otherwise. Hinges and bearings are not a good enough path, so small braided wires are installed to join moving surfaces to main structure. In the absence of the bonding connections static discharge will take place, particularly in precipitation, making radio communication difficult or impossible because the static discharge is in the radio frequency range of the electromagnetic spectrum.
Why the British decided to write the requirement for bonding all over the airplanes and other countries did not but instead just made it a part of normal maintenance and design I don’t know.
Thank you, that’s the most convincing explanation to date even if it doesn’t explain the numbers that seem to be associated with the W/T stencils.
This was early days for voice radio in aircraft as I said and the RAF was one of the earliest to use this ‘black art’ so perhaps it helped remind airframe fitters of the requirement for grounding.
Michael
The W/T was a stencil, used as an inspection stamp, to show that the earthing had been tested; a short circuit could cause sparking, and interference with radio reception. The numbers, usually D.T.D.-----, (Directorate of Technical Development) were to signify the system of paint used e.g. 751 = light wooden, 752 = light metal, 753 = heavy metal. Wellingtons, for instance, because of their strong, geodetic, structure, could stand more tautness, on doped fabric, than Tiger Moths, with wooden construction, therefore Wellingtons received heavier doping than others. Wartime schemes were D.T.D. 83, or 83A, with a suffix “C” for cellulose surfaces, or “S” for synthetic.
Edgar
That might explain some of the lettering on the fuselage side above but I’m not sure it relates to the markings on the underside of the tailplane and elevator which, you will note, are identical, except that the elevator also carries the aircrafts serial - P3351. I can certainly see why that would be there - so if it should be found lying around they’d know what aircraft it came off (assuming its smoking remains were not in the near vicinity).
These stencils are reproduced in the Trumpeter 1:24 Hurricane and it would be interesting to establish if they are correct for the subject Mk1.
Michael