Radio Control Scale

Author: Stan Alexander

Edition: Model Aviation - 2010/04
Page Numbers: 102,103,104

Building a cowl from balsa

While working on my Piper PA-11, I was thinking about different ways to make a cowling to cover the cylinder heads, as on the full-scale aircraft. Deciding, finally, to invert the engine helped make the job easier.

For a project such as this you could carve a cowl from a balsa block or make a form and lay one up with fiberglass. Another way is to "block it up" using balsa sheets, and then carve and sand the structure to the outline needed for the cowl. Sometimes it's quicker and cleaner to do this, although my wife couldn't figure out how the house got so dusty.

After measuring the length of the cowl and the distance between the finished cowl and the windscreen, I ordered balsa for this cowl and for a couple other projects I have in the works. One sheet of 3/8 x 4 x 30 balsa made the outline for all four sides of the cowl, as well as the top and bottom. Another sheet of 1/2 x 4 x 24 balsa served as filler for the front upper and lower sections, which would be carved and heavily sanded and later filled for the fiberglass. I also added a block of 3/8 x 1 balsa to the bottom of the sides. Using yellow Elmer's wood glue, it dried overnight and sanded easily.

I took the nose bowl outline off of my three-view and enlarged it to the proper size for the model. Balsa USA's 1/3-scale J-3 Cub is a great reference for the PA-11, in a much larger size. I made several copies when I achieved the correct size and prepared to make the first cowl. Why carve it out? Because it's simple and, except for the fiberglass cloth later, the smell is almost nonexistent.

The cowl is almost square at the back. The sides are 4 3/4 inches in length, with the thinnest part at the back end where the cowl fits over the fuselage just in front of the windscreen. I did all of this work with hand tools: a saw, an X-Acto hobby knife, coarse and fine sandpaper, a sanding block, and a drill for the prop shaft opening.

For this project, a good tape measure is crucial. When I start a piece such as this cowl, my rule is to use the same tape measure until I'm finished, because they can vary slightly. My sanding block is a short piece of straight 2 x 4 wood. You should have several of these, in different lengths and shapes, for sanding while working on models. I use thumbtacks — three per end — to keep the paper tight and straight. Using a 2 x 4 instead of a piece of wood with less width gives you more to hold onto and allows you to press harder, to take off more material per pass. It works well. Be careful, especially on soft balsa; the coarse paper will remove more balsa than you might think.

I also fashioned a couple of seats from sheet balsa and flight controls for the interior. The kids here have been arguing about who is going to sit in the front seat. Amazing.

Around Scale

Every once in awhile I receive photos from locations across the country where scale contests or scale fly-ins are held. Bruce Harlow sent me information about a World War I fly-in, with photos by Jack Bushmaker.

The Northwest R/C Aviators club hosted the Dawn Patrol Fly-In at the Yard Ranch Flying Site in Kellogg, Oregon. The field, which is directly off Interstate 5, has roughly 80 acres of short-mowed hay. By August the grass is starting to turn brown.

It seems as though more manufacturers and kits are dedicated to WW I aviation than any other era. Proctor Enterprises, Arizona Model Aircrafters, Balsa USA, and Glenn Torrance Models represent a large portion of the kit industry in the U.S. Other manufacturers sell designs for this era too; at least 75% of these companies' models are of pioneer or WW I aircraft.

With the club's field next to a river, the morning fog gives the effect of WW I before “dawn patrol,” so that is how the event obtained its name. Spectators and 31 pilots from six states, who brought 76 airplanes, attended this gathering.

The Northwest R/C Aviators held several diverse events to raise participation at this fly-in, including a pre-WW I event for models of aircraft manufactured before 1914. There was also a Proctor Antic event, which involved 21 Antic sport models of all sizes.

Bruce Harlow served as the contest director for this fly-in. It takes many dedicated workers to make such an event happen.

If you are in the western part of the U.S. in August, this looks like a great field and a talented group of modelers with whom to fly. I hope to see them there.

Upcoming Events

Like the rites of spring, scale contests start popping up across the country this time of year. One of my favorites is held roughly two hours from where I live, in Nashville, Tennessee: the Mint Julep Scale Contest. This year the dates are May 14–16.

The Southern Indiana R/C Modelers host this event each year, and it takes place at the Rough River Dam State Resort Park in Falls of Rough, Kentucky. This is roughly an hour's drive north of Bowling Green, Kentucky.

For many years, Dale Arvin and John Guenther co-directed the Mint Julep. Paul Cain has taken over as contest director, and things are going well.

This venue provides plenty of asphalt to fly off of (a full-size runway), and Master of Ceremonies Dale Arvin provides the entertainment. This is a great time for the family and for all.

JR has scheduled the JR Aerotow for June 4–6, 2010, in Champaign, Illinois. This event features large-scale gliders that are carried aloft by powered tug models. Check the JR website for more information.

FAI Scale

For those of us aeromodellers who are interested in international competition, the FAI website is the source for most contest information. The FAI Sporting Code is the equivalent of AMA's Competition Regulations.

The new 2010 Sporting Code for F4 (Scale) competition, including all classes therein, has been posted on the website. Be ready; with 81 pages for the printer, there's lots of material.

To get to the updated Sporting Code, go to the CIAM (International Aeromodelling Commission of FAI) home page and click on "Documents." Scroll down to "FAI Sporting Code Section 4—2010 Edition" and click on it. From there, go to "F4 Flying Scale Models" and click on the "Belgium" download site.

Some of the best diagrams I've seen for RC, as well as CL Scale maneuvers, are included in these pages. The depictions give good reference for centering maneuvers and the shape and size of each one.

A new provisional class is F4H, which is a sport-scale division for RC Scale. This category has been in existence for only the past year. It has gained popularity in Europe, where it was flown at the 2009 European Scale Championships.

A provisional class that has been around for a few years is F4G, for "Large Scale Radio Control Models" that weigh more than 15 kilograms (33 pounds). In the U.S., we have learned that, with scale airplanes especially, the bigger they are, the better they fly. Europe is also familiar with big models.

The 2010 Scale World Championships will be held in Czestochowa, Poland, July 30–August 8. Three countries—Great Britain, China, and Spain—have submitted bids for the 2012 World Championships.

As soon as a venue selection is made, I'll let you know. It should be sometime late this summer. It looks like the new classes are having one of the desired effects: more participation from organizers.

If any contest director out there is interested in hosting a scale event, please contact either the AMA Competition Department or me; one of us will be glad to assist you.

Resources, including blank score sheets, are available from the NASA (National Association of Scale Aeromodelers) website.

Resources

The Antique Airplane Association, located in Blakesburg, Iowa, has a full-scale fly-in each year during Labor Day week. In 2009, more than 360 aircraft (a record, I believe) and more than 1,000 people were in attendance.

Airplane makes represented included Bellanca, Piper, Aeronca, Bücker, WACO, Stearman, Rearwin, Travel Air, and others. There were lots of sticks, stringers, and round engines.

For information about, history of, and great photos and videos of antique airplanes, the Antique Airplane Association has a great website. It might inspire your next build!

On the Internet

Websites with good, clear photos of aircraft from the Golden Age of Aviation are rare. Thanks to Mike Gretz for sending me information about a site that features aircraft and scenes from the 1934 MacRobertson Race. Check out the Flightglobal AirSpace 1930s images in the Sources list.

Fair skies and tailwinds! MA