21st February 2004

Today's test was conducted whilst giving a show and tell to the local EAA chapter (Chapter 245). The fuel tank was filled with 94 octane fuel and the aircraft was wheeled out into free air. Previously the tests had been conducted with most of the airframe in the workshop with just the propeller extending to relatively free air. The location was about twenty feet from the workshop door. In positioning the airframe away from the building the airflow could enter the propeller disk from the front rather than the side as had been postulated for the previous location.

In addition to the new location, one of the members of the local chapter had located a strain gauge which was good for measuring up to 1000 lbs of thrust. We attached the strain gauge and conducted the power test in a similar manner to the previous tests. The engine reached a maximum of 4360rpm and created 500 lbs of thrust which was significantly above expectation. Don Bates's model had predicted 4127 rpm and 414lbs of thrust.

The following plot indicates the relevant engine/propeller speeds with the addition of the thrust data.

The next task is to install the cooling system so that the tests may be conducted over a longer period.