Mini Kestrel (oz11607)

About this Plan

Mini Kestrel (AKA Mini Kestral). Radio control sailplane.

Note for the original 2-page Mini Kestrel article online (RC MicroFlight site is now defunct) see waybackmachine at: http://web.archive.org/web/20050320153757...

Quote: "Way, way back in the early days of RC, I designed a sailplane (a glider that can ride thermals) for my single-channel equipment so I could get a taste of the relatively new sport of RC soaring. Because of the limitations of my equipment, this new bird would have to be extra stable - especially on the high-start. As usual, I was in a big hurry and wanted a quick building project. Happily, all of these goals were met and, as they say the rest is history. The Kestral (oz3719) a 72-inch-span sailplane, was featured in Model Airplane News.

With the appearance of tiny modern multi-control equipment, I decided to have a go at scaling the Kestral to a smaller size for the smaller fields in use today. In fact, there’s no reason not to enjoy the Mini Kestral in a large building. A gymnasium would be a tad crowded because this little bird can glide from one end to the other on an easy hand-toss.

There are several reasons to build a small sailplane. First, it’s just plain cute! Second, it can work lift in areas that would be mighty hard to get a large machine into. I've had some super soaring just by hand-tossing this little bird into 'ridge lift' along the edge of a long building or on a small, crowded hillside, so there are many options come flying time.

A glider with wings this narrow would usually be very inefficient at low speeds. When I first built one of these birds, it was a real disappointment - cute, yes; but its gliding performance was pitiful. When I told my modeling friend Woody Blanchard about my wasted effort on a small, inefficient glider, he asked to see it; before I knew it, he had glued some strips onto the leading edge (LE) and sanded them to shape. We took the model to his huge front yard for a couple of tosses, and it was transformed. The Mini Kestral has the same LE design, and its performance is every bit as good as hoped for. Thanks, Woody.

The most appealing way to fly Mini Kestral is off a small high-start. I made mine using a 12-foot-long, 0.055 x 0.044-inch rubber strip from Micro-X Models. The rubber strip particularly suited me since it is a dark color and very resistant to sunlight damage (a strip of Tan II rubber can be quickly destroyed by sunlight). The rest of my high-start is 4-pound-test monofilament fishing line of a length that suits the facilities. Although the first flights should be made in calm conditions, Mini Kestral can handle a moderate breeze and still have penetration to spare.

Another consideration in thermal flying is the range of your receiver (I used a Sky Hooks & Rigging RX72 Pro receiver, which has ample range). I would proceed with caution until you know what you can expect.

In the interest of weight savings, I use a 3-cell, 50mAh Sanyo Ni-Cd battery pack for the controls, and everything works well. I use a 6V lantern battery for rapid field charges, and I monitor the voltage with a pocket digital voltmeter. I simply connect the two batteries and disconnect when the receiver pack voltage stops rising. Obviously, you can also use a commercial peak detector charger for the same purpose..."

Direct submission to Outerzone.

Update 14/4/2023: Added article, thanks to theshadow.

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction