Hello Everyone,

I just began scratch building a Sun Ray biplane which was featured in March 1975 RCM magazine. I can post a few pictures of my build if anybody is interested.

Wingspan: upper 51", lower 38"
Wing Chord: upper 9", lower 6-3/4"
Total wing area: 700 square inches
Airfoil: symmettrical
Wing Planform: constant chord
Dihedral Each Tip: no dihedral
Overall Fuselage Length: 50-1/2"
Stabilizer Span: 21"
Rec. Engine Size: 61
Fuel Tank Size: 12 ounce
Rec. No. of Channels: 4
Weight Ready to Fly: 120 ounces
Wing Loading: 24.6 oz./sq. ft.


Quote from RCM article: "This is a fast biplane, highly maneuverable and performs all AMA and FAI patterns, is good for open pylon, and makes a great all around sport plane for the Sunday flyer. She's extremely steady and stable in high winds, with easy stall characteristics and slow landing speed. The wide stance landing gear sets up good control in ground maneuvers, landings, and take offs. One of the most remarkable features of this airplane is it's ability to do sustained knife edge flight, and starting from straight level flight, will climb out and complete a 270 degree knife edge loop! The plane is completely predictable in all flight maneuvers."

I've already cut out several parts including the gull wing spar from 1/4" ply. I'm using notebook paper to trace parts on the plan. I taped a few sheets together for making a fuselage side template. The notebook paper isn't very transparent but I was able to see thru good enough to trace parts.

Next I want to make the wing ribs. I need to make 18 identical ribs for the upper wing and 24 identical ribs for the lower wing. Cutting these individually would take a long time. Anybody remember a method of stacking balsa blanks between two plywood rib templates and then sanding them to shape. I think you drill two holes thru the stack and bolt them together before sanding. Is that how it's done?

Anybody have a March 1975 RCM handy? I wish to see if the article has any helpful construction photos. My RCM plans only included a copy of the text. Real bummer the photos aren't included.

Found these Sun Ray pictures in another thread.


Mike