Experimental aircraft pilot reported a runway excursion upon landing.

Narrative:

Aircraft is an experimental gyroplane undergoing its initial phase I testing. The flight entailed testing cooling duct effectiveness while in pattern. Takeoff and climb were uneventful. Upon turning on downwind leg of pattern; pilot noticed engine coolant temperatures at redline; and asked tower for full-stop landing; which was cleared.approach and flare were uneventful; but upon initial roll-out; aircraft veered to right; and momentarily rolled off runway; before pilot was able to correct. Pilot then re-aligned on runway; and continued to decelerate; eventually leaving runway for taxiway. Tower asked if assistance was needed; but pilot declined; and taxied to hangar once rotor was stopped.problem was caused by pilot's inattention to roll-out due to high engine temperature concerns; and improper directional control. Corrective action will entail: 1) aircraft will be grounded to allow additional cooling modifications; and 2) manufacturer's chief pilot will be contacted with request for additional instruction and possible flight training for pilot.

Original NASA ASRS Text

Title: Experimental aircraft pilot reported a runway excursion upon landing.

Narrative: Aircraft is an experimental gyroplane undergoing its initial Phase I testing. The flight entailed testing cooling duct effectiveness while in pattern. Takeoff and climb were uneventful. Upon turning on downwind leg of pattern; pilot noticed engine coolant temperatures at redline; and asked Tower for full-stop landing; which was cleared.Approach and flare were uneventful; but upon initial roll-out; aircraft veered to right; and momentarily rolled off runway; before pilot was able to correct. Pilot then re-aligned on runway; and continued to decelerate; eventually leaving runway for taxiway. Tower asked if assistance was needed; but pilot declined; and taxied to hangar once rotor was stopped.Problem was caused by pilot's inattention to roll-out due to high engine temperature concerns; and improper directional control. Corrective action will entail: 1) aircraft will be grounded to allow additional cooling modifications; and 2) manufacturer's Chief Pilot will be contacted with request for additional instruction and possible flight training for pilot.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1629729
Time
Date	201903
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Amateur/Home Built/Experimental
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	None
Flight Plan	None
Person 1
Function	Single Pilot
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 41 Flight Crew Total 3450 Flight Crew Type 54
Events
Anomaly	Aircraft Equipment Problem Less Severe Ground Event / Encounter Loss Of Aircraft Control Ground Excursion Runway