Prism Isotope RC Kite Plane at SEFSD – January 2019

I live in Minnesota but spend January in San Diego. I enjoy flying with the Silent Electric Flyers of San Diego (SEFSD) at the Mission Bay field (not to mention the fabulous banquet in January), but I needed a reasonably sized model airplane that would travel well on an airline. Last year, I modified a Prism Zero G Glider Kite (purchased at the kite store in Seaport Village) for this mission (see the March 2018 SEFSD Peak Charge for details).

This year I decided to design a more robust Kite-Plane from a Prism Isotope kite purchased from the kite store in Seaport Village ($55). It flies quite well as a kite. As an airplane, it flies even better. High overhead, it looks like a kite without a string, traveling cross country.

A light weight rudder (foam board) provides yaw/roll control (using dihedral). The dihedral is accomplished by pulling a tight string across the back of the kite from the right corner to the left corner – like you have all done with the typical diamond kite. The motor is gimbaled up and down to provide pitch control. This gives very effective pitch control as long as you have some power applied to the motor. When you cut the throttle it becomes a glider with only yaw/roll provided by the rudder. To land, you need to add some power and a lot of up “elevator” to enter a high alpha mode. If you play it just right, you can “plop” it down right at your feet. The conversion was very successful. It can be flown either as a kite or airplane. All of the special fittings for this Kite-Plane were created in 3D CAD and printed on my low cost 3D printer. All the parts could be built up with wood, but the 3D printing process allows a lot of tweaking/redesign in a short period of time. I think the basic kite frame is fiberglass. I used some 3/16 wood dowels and carbon fiber rods along with the 3D printed fittings to complete the structure.

The empty weight is 576 grams and the All Up Weight with a 3S 1500mah Lipo is 715 grams. The wing span is 48 inches. The motor is a Cheetah 2212-13 1000 KV with a 10 x 4.5 prop. It flies nicely with just under 50% throttle. Measured flight time is 21 minutes when the 3.6V warning beeper starts telling me it’s time to land. It handles wind very well up to point. At the SEFED field, I was able to fly it slow enough to fly “backwards” with an 8 mph breeze.

Since we stay in Coronado for the month of January, the Kite-Plane makes a great backpack airplane. I ride the Coronado Ferry to the Broadway Pier, then take the trolley to the Morena/Linda Vista stop. The bike takes me the rest of the way to the SEFSD field.

Attached are some photos of the Prism Isotope Kite-Plane in the kite configuration, airplane configuration, and backpack configuration.

Rob Jahnke

Member – SEFSD (San Diego CA), MARCS (Madison WI),  Northstar Flyers (Holdingford MN)