85" (85%) Wingspan Airtronics Aquila Sailplane

You might have noticed that I have a "thing" for the Aquila glider. Having built two - one from plans and one from a kit - back in the mid-1970s when the article first appeared in RC Modeler magazine, I developed an appreciation for the graceful lines and the flight performance. In later years I modified a Great Planes 2-Meter Spirit glider to look a bit like the Aquila, and dubbed it the Aquila Spirit. Next, never having had a glider with a wingspan greater than 99", I scaled up the Aquila plans to 105% and built that - my 105% Aquila. That one, which was a lot of work to build, was sold to a guy in Maryland before making a household move.

Now, desiring another Aquila, I decided to build a version with a one-piece wing, but did not want it to be 99" long. Two meters was too short, so I went with an 85" wingspan. That is the one pictured and described here. Because large flying sites are so hard to come by, I elected to install a motor in the nose, but also provided for a tow hook just in case. As noted in the 105% Aquila write-up, because of the tail-heaviness of the unballasted model, replacing the NiCad battery and lead weight in the nose with a brushless motor and propeller, 850 mAh LiPo battery, and ESC only added 2-3 ounces.

Note the unique method for attaching the wing. I didn't want a removable cut-out section in the fuselage, so instead the wing passes through the fuselage and is held fast with a couple small rubber bands. The rubber bands only keep the wing in alignment. I've never seen anything like it before, so maybe I've just invented a new method of wing attachment (patent pending).

Also, rather than building an all-flying stabilizer (stabilator), I opted for a conventional horizontal stabilizer and hinged elevator. It sacrifices the removability for easier transportation and storage, but I'll live with it. The rudder hinge pins are fixed, unlike the original that allowed removal of the rudder as well. It saves weight and complexity. The full-size Aquila and 105%  Aquila needed lead ballast in the nose to compensate to the heavier empennage, but this 85% Aquila balances with no ballast. A final all-up flying weight has not yet been determined. Spoilers were omitted, too. They are very effective on the other Aquilas, but I never really felt like it was something I couldn't live without.

As of this writing, all the construction is complete and the covering is nearly done. I still need to finish installing the electronics and attach the canopy to the frame (always a daunting task). Hopefully, the 85% Aquila's maiden flight will happen within the next two weeks.

Update: See Maiden Flight Photos Below. Final flying weight is 24.8 oz, which with its 580 in² wing area, works out to be about 6.2 oz/ft².

Posted April 15, 2023