Please follow https://ntrs.nasa.gov/search.jsp?Nm=123|Collection|NASA%20STI||17|Collection|NACA&N=4294129243&Ntk=All&Ntt=unmanned%20aircraft%20system&Ntx=mode%20matchall&Nf=Acquired-Date|DAYS_FROM_TODAY+90&utm_source=sti.nasa.gov&utm_medium=Drones&utm_campaign=Highlights.