Addendum to the above, or for those who looked this subject up and were hoping to find real information. The above information from Jack is spot on, except for something different (i.e. not completely ). From a Hawker drawing the following: Fuselage no. 8 x 5 x 1 3/8″ with 1 1/2″ spacing , For smaller lettering (SUPPORT HERE, FIRST AID) 1×3/4×5/32″. Roundel is the std ratio of 1-3-5. I enlarged the numbers from the DataFile Bulldog booklet and the ratios of the numbers are 100% x 70% x 15 to 17%. As most builders know, when you enlarge on a copy machine there is a bit of distortion. If you take the values from Jack, and Ed2 (PowerandPassion-thank you), and DataFile they fall into a close average.
The only complaints allowed are from…..wait a minute. There are no complaints allowed.

Cheers
Ed1