What model or type designation should I use for my aircraft when filing?

You can find the type designation to use for your aircraft when filing a flight plan using the following resources:

     ICAO Aircraft Type Designator Search Page

     DUATS Aircraft Type Designator Search Page

If you have an Experimental aircraft and it has not yet been assigned a unique aircraft type designator, you can enter the ICAO designator "ZZZZ" with a description of the type in the Remarks section of a flight plan.

If needed, use these designators for the following aircraft:

a. BALL – Balloon.

b. GLID – Glider/sailplane.

c. GYRO – Micro-/ultra-light gyrocopter.

d. SHIP – Airship.

e. UAUH – Micro-/ultra-light autonomous unmanned helicopter.

f. UAUL – Micro-/ultra-light autonomous unmanned aircraft.

g. UHEL – Micro-/ ultra-light helicopter.

h. ULAC – Micro-/ultra-light aircraft.

i. UOPH – Micro-/ultra-light optionally piloted helicopter.

j. UOPL – Micro-/ultra-light optionally piloted aircraft.

k. URPH – Micro-/ultra-light remotely piloted helicopter.

l. URPL – Micro-/ultra-light remotely piloted aircraft.

 

Source:  US DOT FAA Order JO 7360.1