infobox Aircraft |image =ZF_Navy_free_balloon.jpg |name =ZF Navy free balloon |type =Gas balloon |authors =Anders Gidenstam |fdm =JSBSim |status =Development |fgname =<tt>ZF_Navy_free_balloon</ tt>}}
This is a US Navy free balloon as used for initial lighter-than-air training during the 1920s to 1940s. It is fairly representative for a type of aircraft that first flew in 1783 and soon afterwards found a shape and construction that it retained (almost) to this day.
===Important controls / keys===
* Gas valve
* W - Weigh-off to 10% of current weight by dropping ballast. Takes about 10 seconds and only works when on the ground.
* D/d - Drop ballast in 1%/0.1% decrements.
* F/f - Open/close the gas valve.
* R - Rip the envelope. Use only close to the ground and when you really really want to stay there.
http://www.gasballooning.net/resources.htm A very good resource for information about and instructions for gas ballooning] . Has links to couple of (old but good) books available in PDF format.
[Category: Aircraft]][ [Category: Balloons]] [[Category:Historical aircraft]]