Deciphering Flutter Prevention Criteria Report

[TinBender]

I am looking at Airframe and Equipment Engineering Report No. 45 Simplified Flutter Prevention Criteria for Personal Type Aircraft.
http://handle.dtic.mil/100.2/ADA955270
I haven't used a typewriter in about 25 years. I can't remember for sure, but I think the older ones didn't have + signs. Are the drawn in "things" plus signs in this equation? These symbols are found on page 15 and 18. There are normal looking drawn-in + signs elsewhere in the report.


Any insight would be appreciated.

 

[bmcj]

 

[ClippedCub]

 

[TinBender]

 

[TinBender]

 

[dcarr]

 

[SVSUSteve]

 

[wsimpso1]

 

[Hot Wings]

 

[pwood66889]

 

[BBerson]

 

[djschwartz]

 

[SVSUSteve]

 

[TinBender]

 

[airborne]

 

[BBerson]