posted 01-03-2019 06:31 PM               

I have several VT70 (Vehicle Test) tiles and an early Columbia tile V070 (Vehicle Orbiter) that was removed before the STS-1 flight. I assume during the tile issues that were well documented. All of these tiles have yellow letters and numbers.

Most of the flown tiles I have seen and sold through the American Space Museum auctions have been white letters/numbers. I have seen flown tiles with yellow text but again early examples.

posted 01-04-2019 12:02 AM               

Types A/C/E have "stenciled" style lettering while types B/D/F have "dot-matrix" printed style lettering.

An example below where both types A and B are used on the same tile. The abbreviations DEN (for densification) and PVT (for pulse velocity test) have been added by hand after those processes were completed (also done in white paint in other examples).

Chuck, I agree with your observations that black tiles with yellow ID number paint (Type A) that have come up for auction seem to mainly exist for the earliest missions of Columbia. Type B tiles are frequently seen unused as part of the Tiles for Teachers program.

For the black HRSI tiles, I've found photos of Columbia at the time of STS-1 with both Types A and B, Challenger having mostly Type B, and shots of Endeavour after its final flight show it having a mish-mash of A, B, C and D (notably much less of A). Many of Endeavour's A's are what I'd term "special tiles" that contain copious additional markings and some even with large painted arrows. So, I wonder if yellow was relegated to this type of duty later in the program with most new tiles IDs painted in white.