Retro RC 1951 Flying Wing

Written by Terry Dunn Retro RC 1951 Flying Wing As seen in the October 2020 issue of Model Aviation.

Bonus Video

At a Glance

Specifications Type: Laser-cut balsa kit Wingspan: 56 inches Wing area: 423 square inches Length: 22.3 inches Radio: Spektrum iX12 2.4 GHz transmitter; Spektrum AR6110 receiver; two Emax ES9051 4.3-gram digital servos Minimum flying area: Sports field Price: $99.99 Components needed to complete: Building supplies; three-plus-channel radio with two submicro servos; 60-watt power system or 1/2A glow/diesel engine Power system: Cobra 2203/52 1540 Kv outrunner brushless motor; Master Airscrew 8 × 4.5 MR-series propeller; Maytech 12-amp ESC; E-flite 2S 800 mAh 30C LiPo battery Flight duration: 10-plus minutes Flying weight: 11 ounces Wing loading: 3.7 ounces per square foot Full throttle power: 7.8 amps; 59 watts; 86 watts per pound

Pluses

Nostalgic styling.
Graceful flying traits.

Minuses

Limited space for electric components.
No hatch grips.

Manufacturer/Distributor: Retro RC (248) 212-9666 www.retrorc.us.com IN 1951, THE EDITORS of Air Trails magazine challenged its readers to design a Free Flight (FF) model that could be any variation of a flying wing. The winning submission was elegantly simple in design and graceful in appearance. It featured a slender, swept profile with pronounced elevons. The model’s defining trait was its large, centrally located, vertical stabilizer. That victorious flying wing is still relevant nearly 70 years later! Retro RC offers a rendition of this nostalgic model in kit form as the 1951 Flying Wing. The modern variant stays true to the original design in most respects, but you have the option of building it as a FF or RC model. You can also choose between glow, diesel, or electric power.

Building the 1951 Flying Wing

Opening the kit reveals laser-cut balsa and plywood parts, along with some balsa sheets and a variety of sticks. Most of the necessary hardware is included. Given the 56-inch wingspan of the completed model, you might be surprised by how few parts are required. That’s one advantage of omitting a fuselage! The model is built over full-size plans. A printed manual guides you through the construction steps. Before you begin assembly, you will need to decide how you want to spin the propeller. I went with a Cobra 2203/52 brushless motor, paired with a Maytech 12-amp ESC. Both are available from Retro RC. If you are going to build the wing for RC, you will also need a mini receiver, as well as a three-plus-channel transmitter that is capable of elevon mixing. I used my Spektrum iX12 transmitter and an old (but trusty) AR6110e receiver.

This laser-cut balsa and plywood kit requires surprisingly few parts for assembly.

The author cut additional access panels in the forward sheeting to mount the battery and ESC.

The wing is relatively thin where the elevon servos are mounted, so you will need to choose servos that are 9 mm or thinner. I went with two Emax ES9051 digital servos. I used medium CA glue for most of the assembly steps. The more strength-critical joints, such as the firewall and dihedral brace, were bonded with 5-minute epoxy. With parchment paper set over the plans, I did not accidentally glue any parts to my workbench or the plans. It is a good idea to read through the entire assembly manual before you begin gluing. This will give you a better idea of the task ahead. You can also determine whether you want to shift around the order of operations or perform any steps in parallel. This model utilizes traditional assembly methods. Experienced builders will feel right at home as they set ribs in place over basswood spars and sand the solid-balsa wingtips. With few exceptions, the lasercut parts fit together quite precisely. There were a few steps in the instructions that did not make sense just by reading the text and looking at the associated photos. In those cases, I was able to figure things out by referencing the plans or examining the actual parts in my hand. Again, this is a relatively simple airplane.

The wing is built over full-size plans using common methods.

The magnetically secured hatches snap tightly into place. Tools must be used for removal.

If you plan to use an electric power system as I did, you will find that your component selections are dictated by the mounting areas that are available. Space is tight! For instance, I originally planned to use a 3S LiPo battery. That plan dissolved when I realized that even my smallest three-cell batteries would not fit in the space available within the wing. Rather than have the battery protrude from the airplane, I changed direction and optimized the power system to use a 2S 800 mAh 30C battery from E-flite that fits within the wing. My only real gripe while building the wing focused on the access hatches that are located in the bottom sheeting near the centerline. Three pairs of magnets hold each of the hatch covers firmly in place. Unfortunately, there is no place to grip the covers for removal. You must place a tool, such as a screwdriver or hex wrench, into a hole in the hatch and pry the magnets apart. I placed both hatches between the bottom spars. In hindsight, I should have located one of the hatches near the leading edge. For balance purposes, I ended up mounting the battery and ESC as far forward as possible. I had to cut two additional hatches in this area to provide access. Having one of the stock hatches up front would have been helpful. It is a good idea to test-fit your power system to the airframe before installing the curved balsa that covers the top and bottom of the motor pod. You will need to cut holes in the wing sheeting to pass the motor leads to the ESC. Trust me, this is much easier to do before the pod sheeting is in place. Neither the kit nor the Cobra motor included screws for attaching the motor to the firewall. Tiny screws are required. I used #0 × 1/4-inch washer-head screws from RTL Fasteners. The manual calls for 12-inch extensions to connect the elevon servos. I guess that not all servo leads are created equal. I found that I actually needed 20-inch extensions. You might want to check what length you require before purchasing extensions.

This tiny Cobra 2203/52 brushless motor provides 59 watts of power for the wing, which is plenty for good performance.

As a nod to vintage modeling techniques, the kit offers the option of using sewn hinges for the elevons. All of the necessary holes are laser-cut and Dacron thread is provided. I took a more modern route and utilized CA hinges. Another option for giving this flying wing a nostalgic appearance is with the covering. You could use silkspan or heavy tissue with dope. I once again took a more contemporary path and used iron-on film. My completed model required nearly 1.5 ounces of ballast in the nose to achieve the suggested center of gravity (CG) location. Even so, my 12.5-ounce wing was below the listed weight threshold. That was a nice surprise because I had made no special efforts to conserve weight while building.

Launching the 1951 Flying Wing requires only a gentle push.

This view of the 1951 Flying Wing highlights its clean profile.

A successful maiden flight is good reason to celebrate!

Flying the 1951 Flying Wing

This model obviously requires a hand launch. I like to grasp the trailing edge right next to the vertical stabilizer. A gentle push forward with the motor at 75% power results in a smooth launch with no loss of altitude. Spinning a Master Airscrew 8 × 4.5 MR-series propeller, the Cobra motor produces 59 watts of power. That might not sound like much, but it is plenty for this aircraft. The setup is capable of steep climbs and a decent turn of speed. I get the most enjoyment, however, when flying this airplane at 1/2 throttle or less. It is whisper quiet and beautifully graceful. The wing loading of the 1951 Flying Wing is ridiculously light. It will fly at extremely slow speeds if you want it to. The usual tradeoff for the benefits of a lightly loaded wing is a low tolerance for windy conditions, so I’ve been pleasantly surprised by how well this aircraft performs in a breeze. It tracks well and does not bounce around as much as some of my more heavily loaded models. I suspect that the flying wing’s minimalist profile really helps. On the subject of its slender shape, this model can be difficult to see when it is coming straight at you. Keep that in mind when deciding on a color scheme. You do not want the airplane to disappear as it transitions through a turn! Aerobatics are not really a part of the Flying Wing’s repertoire. It will loop, but that’s about the extent of it. I have tried rolls and inverted flight without success. This does not mean that the 1951 Flying Wing is not maneuverable. It is great fun to fly low and slow, carving tight Figure 8s in the sky. During my initial flights, I found that the suggested CG location is rather conservative. The wing required an excessive amount of up-trim for level flight and I had inadequate pitch authority to flare for landings. I crunched some numbers and decided that I could safely shift the CG rearward. I have subsequently removed all of the nose ballast and fly with the CG at 5/8 inch behind the stock position. The wing shows no signs of instability with the altered CG. It requires less trim and flares nicely—not to mention that it now weighs only 11 ounces ready to fly! Of course, the ideal CG location is a subjective thing. My suggestion for other builders of this kit is to start with the CG according to the plans and shift it rearward as you see fit. Overall, I am happy with the flight performance of the 1951 Flying Wing. The words "relaxing" and "soothing" come to mind. It is the kind of airplane that makes you want to throttle back, ease into a lawn chair, and marvel at the beauty of this little flying machine while it sips electrons from the battery.

Final Approach

What worked well in 1951 still works well today! The Retro RC 1951 Flying Wing is a classic design that adapts well to modern adhesives, covering, and electric power systems. Let’s not forget the time-saving benefit of having a laser-cut kit! This simple model builds quickly, looks fabulous, and provides a relaxing flight experience.

The 1951 Flying Wing is a graceful and relaxing flier.

SOURCES: E-flite (800) 338-4639 www.horizonhobby.com/e-flite Emax www.emax-usa.com Master Airscrew (916) 631-8385 www.masterairscrew.com RTL Fasteners (800) 239-6010 www.rtlfasteners.com Spektrum (800) 338-4639 www.spektrumrc.com

By Terry Dunn | [email protected] Photos by Lee Ray and the author

Comments

The 1951 Flying Wing

Terry,

I just read the article on the wing and it looks like a fun project. Maybe put a folding prop on it and so some soaring. It would also be better for landing.

Dennis

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