From the G4ILO’s Shack: http://www.g4ilo.com/index.html
I am pleased to announce a successor to my popular HF band propagation program HFProp (http://www.g4ilo.com/hfprop.html). VOAProp has a similar user interface, but uses the VOACAP propagation model. Developed over 50 years by the US Navy Research Laboratory and the Institute of Telecommunications Sciences, with sponsorship from Voice of America, and validated using thousands of reception reports from Voice of America short wave radio listeners, VOACAP is probably the most accurate HF propagation model available.
VOAProp will show you the typical expected propagation for any month and time of day, from now back to the earliest days of radio. It can also generate a point to point propagation chart showing the best time of day, and band, to try to make a contact with any given location.