The investigation of the relight performance of the CT-114 aircraft with JP-8 fuel

This thesis investigated the relight performance and defined the relight envelope of the CT-114/J85-CAN-40 engine using JP-8 fuel. This was determined by attempting airstarts at planned combinations of altitude and windmill RPM, and then recording the success or failure of each attempt, A total of 11 aircraft/engine combinations were tested for statistical confidence. The intention was to establish a relight envelope based on cold soaked aircraft because relight performance of cold fuel is poorer than warm fuel. Some of the flight testing was conducted when the ground ambient temperatures were below -20°C and the aircraft and fuel were cold soaked to near this temperature. The relight performance of the CT-114/J85-CAN-40 using JP-8 fuel was found to be satisfactory and comparable to the relight performance of JP-4. This was likely due to the excellent performance of the CT-114’s high energy ignition unit. JP-8 relight and acceleration performance improved at lower altitudes and higher windmill RPMs. It was hypothesized that if testing had continued to higher windmilling RPMs, maximum RPMs should have been reached above which starts would have been unsuccessful due to being outside the ignition loop. All test point failures were characterized by the RPM hanging up at intermediate values between 27% to 38% RPM. It is hypothesized that this was due to low airmass flow through the engines and/or that the engines were slightly unbalanced. Within the limited scope of testing, JP-8 fuel temperature had no effect on ignition performance of the CT-114 aircraft.