Amateur built aircraft performance testing

The lack of documentation of the performance characteristics for amateur built aircraft is identified as one of the problem areas associated with the increasing activity in this field and is singled out for further consideration.

The objective is to provide the amateur builder with sufficient background and details to allow development of a flight test program to evaluate the cruise and climb performance of a typical amateur built airplane on approximately the same basis as that used for production aircraft. To accomplish this, the theoretical background for level cruise performance and climb performance determination is presented along with specific data acquisition and data handling recommendations that are easily applied to the amateur built aircraft.

To broaden the usefulness of the approach for amateur builders, a method of constructing engine power charts for sea level part throttle operation and altitude operation from the basic engine power curve was developed. Validity of the method developed to derive the power charts was checked by comparison with manufacturers' information. Engine power charts were derived from the basic power versus rpm curve for selected engines for which there were also complete power charts available. . The derived power charts were compared with the manufacturers' power charts. Results indicate that the method can provide power estimates over the 50 to 100 percent power range within ±4 percent.

The recommended flight test and data handling techniques are illustrated by use of a worked example, using a typical amateur built aircraft design for numerical inputs.

The suggested flight test program requires a minimum modification or addition to the aircraft. It is recommended that the performance information resulting from such a flight test program be included in the aircraft records that accompany the aircraft.