Block Number
In 1941 block numbers were added to designations to show minor equipment variations between production blocks. The block number appears in the designation between the model suffix and manufacturers code (for example F-100D-85-NH). Initially they incremented in numerical order -1, -2, -3 but this was changed to -1, -5, -10, -15 in increments of five. The gaps in the block numbers could be used for post-delivery modifications, for example a F-100D-85-NH could be modified in the field to F-100D-86-NH. Not all types have used block numbers.
Read more about this topic: 1962 United States Tri-Service Aircraft Designation System
Famous quotes containing the words block and/or number:
“For Jews demand signs and Greeks desire wisdom, but we proclaim Christ crucified, a stumbling block to Jews and foolishness to Gentiles...”
—Bible: New Testament, 1 Corinthians 1:22-3.
“I cant quite define my aversion to asking questions of strangers. From snatches of family battles which I have heard drifting up from railway stations and street corners, I gather that there are a great many men who share my dislike for it, as well as an equal number of women who ... believe it to be the solution to most of this worlds problems.”
—Robert Benchley (18891945)