105% Airtronics Aquila Sailplane

The Airtronics Aquila sailplane appeared in the May 1975 issue of R/C Modeler magazine.

The Aquila has been converted back to its original pure sailplane configuration (no electric power). I removed the e-power firewall and cowl and glued the pine nose block back in place. You can see in the photos where the division line is from where Monokote was applied across the joint. It still looks good, but you can see the line. There is still a little adhesive residue on the transparent red Monokote that you might be able to remove, but I didn't want to risk it. Lots of construction photos and video below.

January 10, 2015: Not being able to hold off any longer, I finally began working on a scratch-built version of the Aquila. I had the good folks at Staples enlarge the plans to 105% to push the wingspan just over 100" (~104") so it will be my biggest sailplane ever - yeah, I know, lame. By scaling up so slightly most of the structural components like the spars, balsa and plywood, etc., will be able to stay per the original without risking overstressing. However, since this Aquila will sport a brushless motor in the nose (sacrilegious?), I am beefing up some of the areas and using harder balsa in places I might not have otherwise. Since I do not have easy (pronounced "affordable") access to the large pieces of 1/8" LitePly specified for the fuselage sides, medium density 3/16" balsa is being used instead, and will be judiciously carved and sanded to apportion strength and weight as experience guides. None of the original custom hardware - nylon stabilator control horn, special all-flying rudder hinges, canopy, etc. - is available anymore, so everything had to be made from scratch as well. The positive Hoerner wingtips were shaped per the original. I will post photos as they become available.

Video tour of the completed 105% Aquila - April 11, 2015

The Aquila appeared in a Cox / Sanwa ad in the May 1977 issue of Model aviation magazine.

As of today I declare the 105% Aquila to be officially complete! The final flying weight is 51.2 oz., resulting in a wing loading of 8.6 oz./sq.ft. That is a tiny bit more than I would really like it to be, but she has a very strong frame that should endure. Since the motor was replaced with a tow hook, I now need to find an open field large enough to accommodate the full-size Hi-Start launcher (~800 feet needed). The Up-Start (~300 feet needed) did well for my 2-meter Spirit glider, but it'll never be able to launch the Aquila. Quite a lot of work goes into planning and executing a plans-built model, and is further complicated when you change the size and a few aspects of the implementations. It's no wonder s many people these days have either never built a model or have given up building. Here are a few photos of the radio installation and other details that might be helpful if you decide to build your own some day.

The color scheme, BTW, was suggested by Melanie. She likes my Old Spice aftershave lotion aroma and thought the transparent red and cream colors of Monokote would look nice - and they do. I considered doing the Old Spice logo on the fuselage, but figured the company might try to sue me for infringement.

The stabilator control horn is made from 0.062" fiberglass printed circuit board material, and sections of 1/8" brass tubing were epoxied as shown, being careful to keep the tubing at right angles wrt the fiberglass control horn. 3/23" music wire passes through the tubing and into the two stabilator halves.

The original all-flying rudder hinges were heavy duty nylon jobs with a tab to be inserted into the fuselage and rudder, and had a hole lengthwise to accommodate a 3/32" music wire hinge pin. The ones shown are fabricated from sections of 1/8" brass tubing with a piece of fiberglass cloth tightly wrapped and epoxied around them. Clamps pulled the cloth tight and held it while the epoxy cured. Afterward, the epoxy-impregnated tabs were trimmed for insertion into the frame members. It worked amazingly well and is very sturdy.

Tailpost construction is conventional, using custom-built stabilator control horn as seen here.

E-flite 450 brushless motor mount & cowling

Pine nose block replaced with 450 brushless motor and cowl with cooling slots. Nose block can be re-attached using cowl mount screws for a quickly reconfigurable sailplane. Underside of Aquila showing belly skid & tow hook.

Note: The Aquila has been converted back the to pure unpowered configuration again.

Back in the late 1970s I built an Aquila from plans that appeared in RC Modeler magazine, then I built another Aquila in the early 1980s from a kit. Both are long gone. About 6 months ago while waxing nostalgic about the Aquila, I decided to build another, but this time I had the plans enlarged to 105% to get the wingspan over 100" while not having to change airframe component sizes. This version has a 450-size electric motor for power. I wanted to determine the amount of down-thrust needed to prevent a nose-high climb prior to final nose shaping and canopy installation. For this maiden flight, there was about 8 degrees, which was not enough. It really needs about 12 degrees at full power. As you can see from the video, the flight went flawlessly. It was very gusty so I only put in one flight. The wing spoilers work like a charm and bring the Aquila down FAST when fully deployed. I do believe that I'll remove the motor and its support equipment and convert the Aquila back to its original tow line format. That'll make it more authentic and reminiscent of old times (and save a few ounces of weight to boot). Thanks for watching.

A month or so after completing my 105% Aquila sailplane, I decided to convert it to electric power. I would have preferred to fly in pure sailplane mode, but there is no field in my area large enough to safely employ the full-size Hi-Start towline. E-power was really the only option without needing to drive long distances to fly. The nose block was carefully cut off so it can be re-attached for reverting to unpowered flight. The motor and cowl bolt on for easy swap-out. Here are the details of the installation.

I finally got around to processing and uploading a video of my 105% Aquila sailplane with a short narration about its unique features. The flight was made on July 26, 2015, in Kernersville, North Carolina, across the street from where we lived at the time (we have since relocated back to Erie, Pennsylvania). It was a typically hot, humid day there, and the sun was shining brightly - up until a couple minutes after I launched, and then it went behind some slow moving clouds for about 20 minutes. After a total of 25 minutes in the air I decided to land and wait for the clouds to clear. Once on final approach and committed to landing, the sun appeared again. If you watch closely, you can see a few seconds before landing where the Aquila makes a sudden drop toward the ground, demonstrating how effective the spoilers are when fully deployed.

104" (105%) Wingspan Airtronics Aquila Sailplane