Sundancer (oz7984)

About this Plan

Sundancer. Radio control sailplane.

Quote: "A rugged, easy-to-build Standard Class sailplane that combines economy with maximum performance for the sport or competition flyer. Sundancer, by Robert Dellacamera.

The Sundancer sailplane design was conceived to do many things well. It is a high performance, ruggedly good looking, economical and easily built Standard Class sailplane. The design uses a maximum performance airfoil with a speed range as broad as you will find anywhere, and can operate at low Reynolds numbers to take advantage of the low overall weight. Speaking of weight, how's 26 oz with 7 oz of radio included?

The fuselage design takes advantage of the pod and booms low drag characteristics. Turning performance is where the low drag figure shows up best as maneuvers with this model are crisp and accurate. Thermal turns are tight and flat while speed is maintained.

The wing has an aspect ratio of 16:1 with a thin undercambered airfoil and polyhedral. The airfoil performs well at light and medium wing loadings and has a broad speed range not found in most undercambered foils. 'D' tube construction is used with spruce spars and leading edge resulting in a strong warp free wing.

The horizontal stabilizer has generous area and a lot of travel to provide positive control in the pitch plane. The Warren Truss design is easily constructed and fairly resistant to warping. The hinging mechanism provides smooth operation with easy field assembly, tear-down and storage without disturbing any control linkages. Another feature of the mechanism is that the elevator is securely positioned in all normal flight maneuvers, but if you have a hard landing the surface falls out unloading the control system which minimizes damage.

The generous use of spruce and plywood and just plenty of beef in the pod makes this plane stand up to punishment that would crumble many. The wing uses spruce structural members for impact resistance and torsional strength. The finish of the fuselage is important to ruggedness also. Glass and resin are hard to beat as they provide the most armor plate for the weight you can get.

The materials used are all standard lengths and thicknesses. All the blocks can be obtained in kits of assorted blocks sold in most hobby shops for about 89c. The wing ribs are probably the toughest task of the whole project. I use the template method to carve out the set of ribs in a block and it works like a charm. Using blocks in the pod is the easiest method of making compound curves with minimum filling. The prototype has no filling material used in its construction.

To sum it up, the Sundancer represents a year's development effort aimed at making a truly competitive Standard Class soarer. It is light for good thermal performance and super sleek for minimum parasitic drag which gives an extra broad speed range for good penetration and slope soaring. The 'trick' airfoil is nine percent thick and gives good lift in light air, while it does not get draggy in stiff conditions. The result of all these design innovations is a high performance Standard Class sailplane that is extremely light, surprisingly strong, and easy to build.."

Update 19/1/2022: Added ribs file, thanks to JohnHess.

Quote: "Greetings, I have created a CAD template for the wing ribs for plan oz7984 (Sundancer). I would like to add them to that plan page, so folks can download the templates for laser cutting... Thanks,"

Supplementary file notes

Article, thanks to hlsat, JHatton.
Ribs (dxf) zipfile.

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