Found the same photo but couldn't enlarge it enough; Maj. Dean Hess.
Geo
EDIT; Found another photo of #18 without that writing. It had Korean characters on the right nose reading "By Faith I Fly". For a while it carried the name "Last Chance".
S/N 44-74629. Still lookin'
EDIT the EDIT; Apparently the Korean character were on the left as well.
"Hal Wilson, who was Dean Hess' exec, also supposedly had a #18 as well (which Wilson would joke about with Hess, that his #18 flew better than Hess'). Hal Wilson's had the phrase "Last Chance!" scribed on each side of the fuselage, as shown in the below photos (note that this aircraft doesn't have the characters on the nose like Dean Hess' aircraft, and had a black band around the spinner"
You are right George. However it is not the modern , capital letter L we all know and use while hand writing. It is a result of using computers. In the past the letter looked like that below ... of course the one was "modified" by a writing guy because of making it Italic and more wiggled e.g.... As a result it could have looked like the "S" or "Z" for instance. Do you remeber Zorro? The letter "Z" always looked squiggled didn't it?