If it's unclass, can you point us to an open source?
AFAIK, no F-35B has flown at MTOW (61500 lb) yet - hard to get there without external 2k bombs or tanks. Is the <1500 ft normal or MTOW?
And let's not forget that there's a jet that is designed for 800 meters without all the added ironmongery. And operationally speaking, how much use is a 1500-foot runway capability if you have to bring in the fuel by C-130 because your biggest helicopter carries two sorties' worth for 110 miles?
We're not working out of a German cash-and-carry's car park any more...