A
front-page cover photo of Eric Wallner flying a motorized Easy Riser
at Oshkosh came out in Sport Aviation magazine in 2018.
Subsequent discussions with Eric inspired me to summarize some of the design
changes he made to his 1970's kit when he built it that could be
considered as beneficial to the foot launched glider. Several
of the changes he made were specific to the motorized version which I
will not include in this summary. I
will also not mention detailing changes that I’ve already covered
in my other sections in this blog and are not actual "design changes".
1. All
struts shortened by 3 inches which also required the rudder planform
to be changed. I do not have the pattern for his rudder but from
the photos it appears to have the same, general shape. This
change will also affect the stagger measurement you make and will not
be the 14 inch dimension given on the Pre-Rig plan sheet #3.
2. The wing dihedral was reduced from 6 inch offset to 4 inch offset (a 30% decrease).
3. An
anti-sweepback or drag cable was mounted internally from what I
understood to be the internal leading edge strut gussets out to the
trailing edge rudder bracket. I don’t know what hardware Eric used
to mount this cable. I assume it was 1/16 cable.
4. Shortened the top panel by 6 inches to allow the upper and lower tips to fold down even. This reduces the sail area and hence will affect your wing loading.
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