Electro Aviator Model Plane

Gordon holding the Electro Aviator model plane

Gordon holding the Electro Aviator model plane

 

The Electro Aviator model plane is an attractive, easy to build and smooth flying four channel radio control electric powered sport design that I created in 2006. The Electro Aviator was my second RC airplane plan and was published in the March 2007 issue of Quiet and Electric Flight International magazine. Following is a recap of some of my thoughts and considerations as I created this model, to include construction techniques and tips for a successful first flight.

Purchase the CAD plans

You can purchase a copy of the Electro Aviator CAD plans for $5.00.  I will e-mail you the plans on five (5) sheets, each one a PDF file.  Print the sheets out and enlarge 343%.  See PayPal button at the bottom of this page!

Initial design

I was fairly new to the world of model aircraft design when I drew up the Electro Aviator’s plans. My only previous design was the Yankee Mike, a four channel sport flyer published in the July 1998 issue of RC Modeler magazine. I drew the Yankee Mike’s plans by hand. While sketching the outlines of the EA I was just starting to get proficient with the use of TurboCAD to prepare a set of plans.

I decided to use a conventional method for the size and moments of the Electro Aviator, emulating existing sport aircraft design layouts. This is always a wise approach for someone starting out creating their own RC models. As with anything new, try and take logical, incremental steps to build on your existing knowledge base.

Electro Aviator model plane side view showing decals

Electro Aviator side view showing decals

With this design approach in mind the main tasks were selecting an airfoil (I chose the Clark Y, a common airfoil shape for sport RC models) and drawing up the required fuselage formers, cowling, wing spars, ribs and tail surfaces.

Model size

I needed to settle on a size for the Electro Aviator model plane. I used experience gained with the installation and thrust of brushless electric motors I was using on other aircraft. I decided to make a design with a 38 inch wingspan, a fuselage length of around 32 inches and an average wing chord of 10 inches. Target weight was planned to be under 25 ounces. The model’s light weight combined with ample wing area result in a wing loading of just 9.5 ounces per square foot, which is a suitable range.


These initial design figures worked well. It turned out that the prototype had horizontal tail surfaces that were just a bit too large and did not seem to “fit” well when looking at the top view. I reduced the tail area on the final version of the model.

The Electro Aviator is designed to use an outrunner brushless electric motor. Tailor the cowling arrangement with cooling holes and front air intakes as required for the motor you plan to use. Use any electric motor you feel is suitable for pulling a 25 ounce model through the air.

Construction notes

The fuselage is straightforward construction and consists of 1/16” balsa sides with an inner 1/16” balsa doubler. I chose to use flat fuselage sides and bottom for ease of construction, but with a curved aft upper deck of lightweight 1/32 inch balsa surface for visual appeal.

Electro Aviator prototype - note oversized tail surface, made smaller on final version

Electro Aviator prototype – note oversized tail surface, made smaller on final version

The tail surfaces are 3/32 inch sheet balsa for simplicity of construction. It is always fun to add personal touches to an aircraft design. I did this with the Electro Aviator by making the vertical fin in a similar shape to that employed by the F-4 “Phantom” fighter aircraft that I flew in during my time in the U.S. Air Force. The distinctive fin shape fits well with the Electro Aviator’s profile.

Landing gear is an integral part of any aircraft design. One of the things you will find as you gain experience with creating various models is that you develop rules of thumb for what works with various wood sizes, motor/prop combinations, etc. This holds true for the landing gear. I’ve found that 3/32 inch music wire landing gear is a good compromise between the weight of the gear and the necessary strength required for grass field operations for a model of this size.

Adjust the length of the gear as required for ground clearance of the propeller, taking into account the size of the wheels you will be using. I used 2.5” foam wheels. The foam wheels weigh hardly anything and the 2.5” diameter works fine on a grass field. If you use smaller diameter wheels there is a tendency for the model to nose over during ground operations.

There are various techniques for attaching the landing gear to the fuselage. I used a 1/16” ply landing gear mounting plate and drilled a series of 1/16” diameter holes around the edges of where the landing gear mates to the ply plate. I used dental floss to “sew” the landing gear to the ply mount, smearing epoxy glue on the music wire and floss. Dental floss is surprisingly strong and this method holds the landing gear in place very well.

You usually need some sort of hatch to access the fuselage battery compartment. I conceived a large hatch placed just behind the cowl and included the two cockpits as part of the hatch. Flexible Mylar hinges keep the hatch aligned. Rare earth button magnets provide an easy and secure method of keeping the hatch securely shut during flight.

Building the cowl

Electro Aviator balsa cowling

Electro Aviator balsa cowling


The technique of using soft one quarter inch balsa formers to build up the cowling works well and adapts itself to a wide variety of electric motor sizes and configurations. The cowl is built around the motor to ensure everything fits into place properly. Cut out cowl blanks from soft quarter inch balsa and cut out the openings in the blanks to allow adequate clearance for the motor. Tack glue the balsa cowl blanks until your motor is fully enclosed.

Slip on your prop/spinner assembly to the motor and trace the spinner outline onto the cowl blank. Use this outline as a guide to carve and sand the cowl to its finished shape. Periodically slip on the spinner to check that shaping is proceeding as planned. Cut out bottom cooling holes on the cowl as required for your engine’s cooling requirements.

For ease of construction I employed a constant chord wing. This means I need to design just one wing rib without the added work of differing length ribs for a tapered wing shape. To give the visual impression of a tapered wing I narrowed the strip ailerons. The effect is convincing and a great example of a simple technique that can be used on other designs.

Computer graphics

Computer graphics are a handy method to add distinctive details to any model plane. I used this technique in two areas for the Electro Aviator.

The first are the pilot figures. I took digital profile “head shot” photos, imported them into PowerPoint (or whatever graphics program you may be using) and printed the pictures (one electronically “flipped” for the opposite side of the pilot cutout) at the exact size I wanted for the cockpit. Glue the picture onto scrap 1/16” balsa and cut out the balsa outline along the profile of the picture. Glue the opposite head photo profile to the other side of the balsa cutout and you have a lightweight pilot figure that can be glued into the cockpit.

Computer generated decals

Computer generated decals

All of the aircraft decals were prepared on the computer as well. The stars on the wings were done in PhotoDraw with the included circle and star patterns. The various squadron patches and emblems were found on the internet using the Google Image tab. Once you find a suitable image, copy it and paste into PowerPoint or whatever graphics program you are using. Letters were done with the normal text tools in the graphics program.

These imagines were then printed directly onto inkjet decal paper, available at office supply stores. Once the images are printed out on the decal paper, spray on some clear Krylon to seal them. Apply the decals just like any other water slide decal. Once the decals are on the model and dry, lightly spray again with the clear Krylon to seal.

With the ability to take any digital image (to include ones taken with a digital camera) and print them out on decal paper the possibilities for enhancing your model are unlimited. And it could not be much easier. Note that I found many of my former USAF squadron patches and put them on the side of the Electro Aviator.

First flights

Electro Aviator model plane

Electro Aviator top view

Prior to your first flight ensure all is in order with the standard preflight checks. Be certain that the wing is completely warp free. With the lighter structures typical with electric flight and the strong iron-on heat shrink coverings, warps can sneak their way in.

Check that control surfaces move freely and in the proper direction. Perform a radio range check with the motor both off and running, a final check of the center of gravity and you’re ready to go.

The Electro Aviator model plane is easy and pleasing to fly with no unusual flight characteristics. It makes a great first time plans built modeling project. With its ample wing area, light weight and a powerful motor, the Electro Aviator lifts off quickly. The plane handles well, but like smaller models it flies best in calmer wind conditions. The aircraft is a natural slow flyer and this translates nicely to smooth landings at a relaxed pace right in front of you, with a short taxi back to clear the flight line. It does not get much better than that!

Purchase CAD plans

You can purchase a set of CAD plans for the Electro Aviator via PayPal.  I will e-mail the plans on five (5) PDF sheets.  Print them out and enlarge 343%.

I will also e-mail the Electro Aviator CAD plans in three formats:  TurboCAD (TCW), AutoCAD Native Format (DWG) and Drawing eXchange Format (DXF).

Any computer can print out the PDF plans (Adobe Portable Document File) through the free PDF reader.  You will need a CAD program to view and print the TCW, DWG or DXF files.

Please send me photos of your completed Electro Aviator and I will post to the website!


Electro Aviator Plan via e-mail $5.00



Detail of Electro Aviator nose section drawn with TurboCAD

Detail of Electro Aviator nose section drawn with TurboCAD

 

TurboCAD plan for the Electro Aviator

TurboCAD plan for the Electro Aviator

Author:  Gordon McKay