A Practical Tiltrotor UAV (PTUAV) has been developed and flight tests are under way. The PTUAV was motivated to pursue low cost and high performance while the full-scale tiltrotor UAV development experience was reflected. The PTUAV was targeted to develop a UAV system which has capabilities of VTOL and faster-than-helicopter forward speed with practical mission load adjusting the lower cost and weight. Vehicle sizing was performed using simple analytical method and scaling full scale vehicle parameters. The rotor and drive system of PTUAV were designed reflecting the full-scale concept but simple and unique concept was adopted. An ironbird for the rotor-drive-engine was fabricated and tested on the ground to reduce risks in integration and to facilitate measurements and modifications. The air vehicle was designed and fabricated reflecting the ironbird test. The flight control system covering the test from ground to conversion flight was constructed and tested. A tethered test was conducted for the verification of flight control logic in heli-mode flight prior to flight test. Currently flight tests are under way after integration issues were resolved from ground tests with the platform.