Making Dummy Engines

Around The Patch

By Thayer Syme | [email protected]

As seen in the July 2023 issue of Model Aviation.

APPARENTLY, Gordon Johnson’s Velie Monocoupe that was featured in the lead photo of my January 2023 column caught more than a few eyes as you all flipped through that issue. Gordon based his delightful model on an enlarged copy of Herb Clukey’s original plans that were included in the Flyline Models kit offering, and many of you have reached out to me about it.

For those who might have missed it, Gordon’s model is worth a second look. The Velie is a relatively simple Golden Age civilian design, with the most obvious opportunity for detailing being its exposed five-cylinder radial engine. Gordon opted to design and 3D-print a dummy Velie engine for his model rather than build it up using traditional methods. I’ve had several emails commenting on his model and engine, and the overwhelming majority have been supportive of his efforts.

Designed by Rich Weber, the Easy Built Models Staggerwing kit is a consistent favorite for Flying Aces Club (FAC) competition and sport flying. This exceptional example was built by Jason McGuire.

Some who wrote to me have lamented their lack of access to a 3D printer or the skills needed to create a file for printing an engine of their own. If you find yourself in that quandary, I encourage you to ask among your friends and clubmates. 3D printing is becoming more affordable all the time, with capable printers readily available in the $200 range.

I do realize, though, that not all of us have the time, room, or inclination to start down the 3D-printing rabbit hole. If you are raising your hand about now, consider that you might already know someone with a suitable printer and just not realize it. Ask around at the field or your next club meeting, and see what turns up. Remember, the answer will always be "no" until you ask.

If you still come up dry, check with your local library. Many community libraries have cooperative maker spaces or can direct you to one nearby that might be independently managed. Given today’s tech environment, I can only imagine that most such facilities would have at least one 3D printer available.

Of course, you can also always do it the old-fashioned way. I have made several dummy engines by stacking alternating disks of various materials and have found them quite suitable. The typical technique involves layering thicker balsa pieces for the cylindrical body, with slightly larger diameter disks cut from thinner stock to represent the cooling fins. I’ve seen great results when using 1/64-inch plywood or manila file folder stock for the fins. My personal favorite, though, is to use a deck of playing cards.

Playing cards are thinner than 1/64-inch plywood and are engineered to flex yet still remain flat. This feature makes them much more durable than fins cut from file folder stock, which will take a set after a bit of mishandling or simply from your finishing efforts.

Designed by his brother and FAC founder Dave Stott, John Stott’s whimsical Hung-Aereon always draws a crowd. A laser-cut kit is available from Easy Built Models.

Drill a 1/4-inch hole through a stack of roughly shaped pieces of stock then slide them onto a standard 1/4-20 bolt and secure them with a washer and nut. The bolt will act as a mandrel so that you can spin the stack for final shaping using a drill, drill press or lathe, and a coarse sanding block or Dremel tool.

After you have the parts shaped, use those center holes to aid alignment as you stack them up. Short pieces of aluminum tubing can be used, or even brass if you need some extra nose weight. You can also sand off the corners from a piece of 3/16-inch square balsa using a few light swipes of sandpaper.

Assuming all dimensions are accurate, you will only need to remove approximately 8 thousandths of an inch from each corner before a 3/16-inch square stick sleeves nicely into a 1/4-inch hole. For reference, 8 thousandths of an inch is roughly 1/4 of 1/32 of an inch, or approximately the same as three to four human hairs laid side by side together. Wield the sandpaper with care and check your progress often.

Leaving the tubing or stick long provides a nice handle for finishing, and you can shorten it to form a locating pin when it comes time to glue the cylinders to your cowling or crankcase.

Depending on the size of your model, any desired final details for your engine can be added with small scraps of wire, wood, and plastic, as well as dabs of paint.

Now stand back and pat yourself on the back.

The author’s dummy engine features cylinders from layered disks cut from 1/16-inch balsa and playing cards. The remaining details are made from balsa, heat-shrink tubing, and styrene.

Easy Built Models

In other news, you might or might not have heard that Easy Built Models has changed hands again. Shannon and John Fairchild purchased Easy Built Models from Dave and Ann Niedzielski in early November 2022, and have done a great job getting up to speed.

Easy Built Models is one of the oldest model airplane businesses still in existence in the US, with a company history that dates back to 1932. As you can imagine, many of its 166 kits feature Golden Age and World War II subjects, and the company has many Sport Free Flight (FF) designs as well. My first Easy Built kit was the 12-inch Art Chester Racer, which I am still flying nearly 30 years after I first built it!

Speaking of FF, yes, most of their kits are. That stated, Easy Built Models does offer a nice laser-cut RC kit for a 57-inch de Havilland Beaver, as well as a gorgeous 72-inch RC sailplane converted from a 1940s-era Towline FF design. Many of the other designs would also be suitable for RC conversions, assuming you know which end of the X-Acto knife to hold and have done something similar before.

I ordered a couple of kits a month or so ago, and my new treasures arrived in just a few short days. They were safely cradled in an oversized outer box, with a healthy dose of peanuts for cushioning.

The 18-inch S.E.5 biplane also has me thinking. I built one for electric FF shortly after the Art Chester Racer and had a ton of fun with it. The latest version of the kit is now laser-cut and should easily carry a small 2S RC system for evening patrols in the neighborhood!

Another look at Gordon Johnson’s Velie Monocoupe with a 3D-printed dummy engine and wheels. Inspired by the Flyline Models kit, the Monocoupe features a traditional lightweight stick structure.

Take another look at the Easy Built Models website if you haven’t recently, and see if something catches your eye. Shannon and John are sure to appreciate your support, and they are counting on all of us to get the company to its 100th anniversary.

That’s all I’ve got for now, so until next time … use the good wood!

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