Answers to some comments on HAV's.
Some rather odd comments that need a few answers so here goes:
Firstly the HAV 304 is a hybrid air vehicle, which means it is a cross between a blimp and a flying wing plus a hoverskirt undercart. It does not need wings and a layer of PV panels would not justify their weight or work too well in Afghanistan. The amount of Helium is fixed and it does not need to be changed unless there was a big configuration change such as changing from medium altitude surveillance to low altitude heavy lift. Then the Helium would be topped up to increase payload, otherwise almost no Helium is required after initial inflation. All military aircraft have to use JP8 fuel which is a cross between jet fuel and diesel. Hydrogen could be used in a civil version but the present engines are Centurion 4.0 diesels which are very efficient anyway.
Secondly the 517 million dollars was for 3 HAV's not one and half the cost is for the special surveillance payloads. Initial prototypes are always expensive but a production HAV will cost less than an equivalent aircraft and far less to operate in fuel terms.
Thirdly forget about storing or compressing Helium and other research programs as they are all too heavy to be useful at present. Due to it's high static weight capability an HAV does not need such systems.
Fourthly the ballast question only applies to normal airships not to HAV's as they can take off heavy enough to avoid a light landing. Even if an extreme condition did arise then sandbags can always be loaded into the cargo bay.
Regards JB ( www.hybridairship.net )