Design Parameters by Jim Marske

The PIONEER II is an effort to develop the ideal all-around
sailplane. As a homebuilders project it is simple and quick
to construct utilizing as few parts as practical. All too
often a builder becomes discouraged by his slow rate of progress,
confused by the complexity of parts and drawings, and loses
interest, abandoning the project. So in this design we made a
special effort to keep the design 'clean and simple'.

Performance dictates two requirements which are basic to the
success of any sailplane, An ability to climb very fast in
limited areas of rising air and secondly, an ability to cruise
at very high speed with very small loss of altitude. In both
realms a low overall aircraft drag is essential. However, low speed efficiency dictates a low wing loading for maneuverability while a high speed cruise requires a high wing loading. Unless a variable geometry wing is adapted to fulfill these requirement very little else can be done. For the sake of simplicity we tried the next best solution, utilize a low wing loading combined with a thin reflexed wing section on an untwisted wing.

The lack of a horizontal stabilizer and aft fuselage section
eliminated all associated drag and weight penalties in addition
to providing the fuselage with a more efficient streamline
fineness ratio. These qualities are the keys to the success
our designs performance, Hence the secret for our exceptional;
'wide' flight speed range.