Model Sailplane Homepage

Kirt Blattenberger holding the Aquila sailplane at Southern Senrior High School (c.1975). Built off of RC Modeler plans - Airplanes and RocketsSailplanes (or "gliders" for the unrefined) have always been one of my favorite types of model airplanes. Even back when the only thing I could afford was the Guillows stick and sheet balsa variety at the convenience store, I tended to prefer the gliders over the wind-up rubber powered models. My first built-up sailplane was a Sterling Models Schweitzer (I think it was a 1-26 model). I was intrigued by its huge (at the time) 42" wingspan, and I loved the graceful lines of the This is not a picture of the model, but of an actual Schweitzer 1-26 sailplane. The link will take you to the 1-26 Association website - Airplanes and Rocketsfuselage. If I recall correctly, it was a real bear to build because of the many tiny balsa part to cut out (I used a single-edged razor blade in those days - X-acto knives came later). There were what seemed like hundreds of 1/16" square balsa stringers to install in the wings, tail surfaces and fuselage. Somehow, I managed to get it completed and covered with Jap tissue. It was very lightweight, and the wings were surprisingly strong for how thin the airfoil was and how high of an aspect ratio it had. As with most of my other models, I cannot recall what happened to it, other than ultimately it must have bitten the dirt.

OS Digital 3-channel radio control system - Airplanes and Rockets


Links, Photos & Reviews

My first radio controlled sailplane was a Marks Models Windward that had a 72" wingspan. It was covered with silkspan and was painted orange and white, with a sunburst on the top of the wings. It flew pretty well, but the kit was very poorly done. The parts had a lousy fit, and the wing was not very strong. It lasted quite a long while, though. The radio was an OS Digital 3-channel rig (see picture of main, and a magazine ad for it). OS Digital 3-Channel Radio System - Airplanes and RocketsThe servos were fairly small for the day, and were actually the rotational type rather than the linear. The range on the system was only about 700-800 feet, and the servos jittered to beat all. Even with multiple trips back to the factory, the performance never got much better. Still, it was better than nothing.

After graduating from the Windward, I took on the Marks Models Windfree sailplane that had a 99" wingspan. It was equally difficult to build, but it flew much better than the Windward. While on a trip to New York to visit relatives in Lackawanna, I looked up in the sky and what to my wonder eyes should appear, but an RC glider floating around. There was a large schoolyard behind my uncles property, so I beat feet over there and found a guy with a High Start and a 2-channel Kraft radio where staring upward. He had that combination receiver + 2 servos unit that Kraft made for a while (the KP2B ???).  He put in some really long flights, so I figured if he could do it,  then so could I. Well, I never did get the kind of durations he did, but made improvements over the Windward times. My Windward was red and white. I have no idea what happened to it or the Windward, other than they both must have met an unhappy fate.

Kirt's Aquila sailplane flying over the atheletic field at Southern Senior High School, Harwood, MD. Water tower in the background - Airplanes and RocketsBack around 1975 or so, RC Modeler magazine ran a feature on a design called the "Aquila." It had incredibly graceful lines and I knew I just had to build one. Airtronics had not yet produced a kit for it, so I ordered plans and built one from scratch. There was a hardware and canopy package available, though, so I purchased it. The pictures at the top of this page are of the Aquila I built off the plans. A radio failure (still that same old 3-channel job) ended its life. Fortunately, by then the kit was available from Airtronics, and my parents gave me one for Christmas. It was very well done and the parts all fit very well. The Aquila was not a beginner's project by any means. What I liked best about the design was the removable, all-flying stabilizer (stabilator). I bought a Cirrus 4-channel radio to use in it and used the wing spoilers. That brought a whole new dimension into RC sailplane flying. I put so many flights on it that the fuselage got worn out (OK, so partially due to some hard landings). Some company began offering an ABS molded fuselage for the Aquila, so I bought one and breathed new life into the plane. The picture to the right of my barracks My barracks room at Robins AFB, GA. Hanging are my DuBro Tri-Star helicopter, my Dumas Pride of PaynPac hydroplane, and the fuselage of my Airtronics Aquila sailplane - Airplanes and Rocketsroom at Robins AFB, GA, includes the ABS fuselage.

Kirt, Philip & Sally Blattenberger with Great Planes 2-Meter Spirit on slope in Hagerstown, MD (c.1993) - Airplanes and RocketsAfter getting out of the USAF in 1982, and getting married to Melanie in 1983, the serious hobby endeavors took a hiatus until my son, Philip, and daughter, Sally, were old enough to be introduced to model aviation. The picture to the left is from while we were living in Smithsburg, MD, circa 1993. That was the first of many Great Planes 2-meter Spirit gliders I would build. We were fortunate enough to live in the country and there were flying spots all around. A large field across the road allowed me to use either a short HiStart (UpStart) or a power pod I built to strap to the top of the wing. A Cox .049 Black Widow took it up about 500' and the pod + engine + propeller + weight Philip Blattenberger holding myt Great Planes 2-Meter Spirit in Smithsburg, MD (c.1993) - Airplanes and Rocketsbarely affected the performance at all. It actually helped on windy days. To top off  My 2-meter Spirit slope soars above Hagerstown, MD, along Crystal Falls Drive - Airplanes and Rocketsthe perfection of my location in Smithsburg, about three miles away was a road named Crystal Falls Drive, and just to the north of it was an open slope that rose about 100 feet above the farm fields below. That was where my first successful slope soaring ever took place. I still beat myself up for ever moving from Smithsburg, but, as they says, hind sight is 20-20.

View looking out over Smithsburg, MD, from High Rock hang glider outcropping - Airplanes and RocketsAerial view of High Rock from hang glider - Airplanes and RocketsAs an aside, my house also had a clear shot of the High Rock hang glider launching spot (click on thumbnails). It was a small outcropping from amongst the trees that was 1000' above the ground below. I loved watching the hang gliders soar up underneath the billowing cumulus clouds and then finally touch down in the field across from our house.

This Great Planes Spirit was built in Colorado SPrings, but the picture was taken in Baldwinsville, NY, about a year later - Airplanes and RocketsOK, so time went on and on and on, and finally I built another 2-meter Spirit. This time we (Melanie, Philip and Sally and me) were living in Colorado Springs, CO. I joined the Pikes Peak Soaring Society and flew at their fine field a few times before eventually moving to Baldwinsville, NY. Philip soloed for the first time on this Spirit. He had a bad habit of hitting immovable objects with it (a shed and a goal post), so it got a little deformed in the leading edge. It repaired rather well, though. I ended up selling it before moving back to Colorado (NY taxes are awful).

Kirt with Great Planes Spectra electric RC sailplane in Loveland, CO (c.2001) - Airplanes and RocketsI decided to try my hand at electric flight and purchased Great Planes Spectra electric powered sailplane while in Loveland, CO, and was able to fly it from an expansive field adjacent to my back yard. The only obstacles to avoid were the cow pies. The Spectra is basically a 2-meter Spirit, with a motor and prop up front. I think it was a 400 size. Rather than use the servo-actuated on-off switch, I used an electronic speed control (ESC). The motor was a real piece of garbage. After about 4 or 5 motors runs, the brushes began fouling with a hard crust layer after every run. It always involved disassembling the motor and cleaning the brushes. I got so fed up with it that I just stopped flying it. We then moved to Kernersville, NC, where we now still live. I dusted off the Spectra Supermodel Melanie holding my Great Planes 2-meter Spectra electric powered sailplane, Kernersville, NC (c.2005) - Airplanes and Rocketsand flew it a few times at a local elementary school. On one ill-fated flight in the winter, my aging eyes told me the Spectra was in front of a big oak tree while on a landing approach, when in actuality, the oak was between my Spectra and me. Needless to say, I was quite shocked when the beast came to a sudden halt and tumbled to the ground. The experience was rather strange because the tree was far enough away that I saw the plane hit before the noise from the crunching of the branches reached my ears (my eyesight is terrible, but my hearing is still very good).

Kirt with Great Planes 2-meter Spirit sailplane, Kernersville, NC (c.2005) - Airplanes and RocketsModification to the Great Planes 2-meter Spirit to replace stock canopy overhang with a built-up fairing - Airplanes and RocketsA couple years later (this past winter), I built yet another 2-meter Spirit sailplane. A modification I made to the Spectra, I also made to this Spirit. It involves replacing the rear part of the canopy that overhangs the leading edge of the wing with a built-up fairing. That canopy overhang is easily damaged. Rather than allow the canopy to extend beyond the rear canopy frame and over the top of the wing, the canopy is trimmed flush with the frame, and a balsa fairing is built onto the wing. Close-up of modification to the Great Planes 2-meter Spirit to replace stock canopy overhang with a built-up fairing - Airplanes and RocketsThis provides what I consider to be a nicer looking interface, and it exposes the canopy to less of a threat of damage. A bulkhead is cut and shaped to match the rear of the canopy, minus 1/16" for sheeting, then a single spine is cut to put in the middle that conforms to the airfoil shape and provides a natural extension from the canopy shape. Finally, two pieces of 1/16" balsa are glued in place, the gaps filled, and sanded to a final shape. The picture to the right shows the finished product.

Supermodel Melanie with Great Planes 2-Meter Spirit Modified with Elite Park 400 Outrunner Brushless Motor (dubbed the e-Spirit) - Airplanes and RocketsBelieve it or not, finding an open field around here in NC large enough to stretch out a HiStart is difficult. Privately owned fields are usually off limits any more because of liability issues (smack a lawyer the next time you see one and thank him). After having my launch line land in a tree, I decided to convert the Spirit to electric. An order was placed with Tower Hobbies (they have been the recipients of about 80% of my hobby money in the last 2 decades) for a Great Planes Triton charger, two 1500 mAh Li-Poly battery packs, and a Master Airscrew 400 brushed motor w/3:1 gearbox and 10x8 folding propeller. The motor/gearbox was much too large and pretty heavy. Dang.

Supermodel Melanie Blattenberger holding my Aquila Spirit - Airplanes and RocketsI wanted to get a good brushless motor, but from what I could see, the cheapest models Tower had started at around $120, and the special ESCs were about $80. Yesterday, Melanie and I went to KayCee Hobbies in High Point, NC, and with the help of a knowledgeable fellow named Robert, we left with an Elite Park 400 Outrunner motor ($55) and an Elite 20-Amp Brushless Speed Control ($42). I think the prices were excellent. I am utterly amazed at how much power is packed into that small motor. Modifications have begun for the installation of the motor. I plan to use a couple degrees of right thrust and down thrust as a starting point. I don't recall what the Spectra used for thrust offset, but it did pretty well with the factory amounts.

Final ready-to-fly weight ended up at 32.6 ounces, compared to 31.5 ounces for the original configuration.

Elite Park 400 Outrunner motor and firewall - Airplanes and Rockets

Motor & Firewall

e-Spirit E-flite Outrunner 400 Brushless Motor Mounted to Firewall - Airplanes and Rockets

Motor on Firewall

e-Spirit Modification looking into the Nose - Airplanes and Rockets

Firewall in Fuselage

e-Spirit View Looking into Nose with Motor Mounted - Airplanes and Rockets

Motor in Fuselage

e-Spirit Firewall - Airplanes and Rockets

Firewall in Fuselage

 e-Spirit ESC and 1500 mAh Li-Poly Battery Pack - Airplanes and Rockets

Motor, Battery & ESC

e-Spirit Modified Fuselage Bottom Showing Cooling Holes - Airplanes and Rockets

Fuselage Cooling Holes

e-Spirit Receiver and Servo Area - Airplanes and Rockets

Receiver & Servos

e-Spirit Modified Canopy Bottom - Airplanes and Rockets

Modified Canopy

e-Spirit Canopy Modification for Cooling - Airplanes and Rockets

Modified Canopy


Click to view the maiden flight of my 2-meter e-Spirit (converted to electric power) - Airplanes and Rockets View the video of its maiden flight as the e-Spirit, July 16, 2005.

We have been having a lot of wet and windy weather here in my area, but I couldn't wait any longer. Yesterday (7-16-2005), I took the e-Spirit out and I gave it a 12 minute and 20 second flight in very strong winds. Under power it just about hovered over the same spot as I climbed in to the wind. Overcast conditions meant no thermals to seek out, but I just wanted to make sure the darn thing would work - and work it did! with the 1500 mAh Li-Poly battery, Elite Park 400 Outrunner brushless motor & ESC, and 10x8 folding prop, it climbed at about a 45 degree angle all the way until almost out of sight. After floating down and fighting the wind, I was able to make three more climbs to about 500 feet after getting down to about 20 feet AGL. This is definitely a good setup - it weighs only 1.1 ounces more than the original sailplane-only configuration.