Shorts SD3-30 Commuterliner (oz10460)

About this Plan

Shorts 330. Free flight scale twin. For AMA Gas Scale.

Quote: "Pushing the frontiers of freeflight; FM presents an outstanding Nats winner. Shorts SD3-30 Commuterliner, by Dave Rees

You have to be a little crazy to make an assault on the National Championship with a homely, boxy airliner like the subject of this article. But I had the fever - twin fever. Anyone who saw Paul Gartner's fabulous Dornier DO-18 twin fly at the '84 FAC NATS was stirred by its spectacular performance. I simply had to try a twin.

So how does one go about selecting a subject that will perform well as a free flight twin for the AMA Gas Scale event? Previous experience told me that ground handling characteristics were very important for good takeoff points. All AMA scale events require that a lot of data be available for scale detail judging. The airplane must be able to fly slow and steady, duplicating as closely as possible the characteristics of the full-sized aircraft. After that, I look for a square, high-wing monoplane to make the building job as fast and easy as I can.

After much digging through the book-shelves, only a few airplanes fit these requirements. The Shorts became the ultimate choice because of its excellent landing gear design, and its refreshing newness as compared to the often over used Golden Age subjects.

The Ulster Commuter. The Shorts SD3-30 is made by the fine old Irish company founded before WWI which built the Sunderland Empire Flying Boats in the 30's. They are, therefore, no strangers to the manufacture of passenger aircraft and have shrewdly analyzed the fast changing airliner market, coming up with the ideal ship for the commuter lines. The SD3-30 has both the best safety record and the lowest price tag of any commercial airliner in service. Almost every airline in the US has several of these hot-selling workhorses that are rapidly becoming the modern day DC-3, only with more passenger comfort. Many readers will have undoubtedly flown on one already.

I recently had the opportunity to fly in a SD3-30 on a business trip and you can bet I was really giving it a close lookover. Piedmont Airlines had at least ten of them pulled up to a long covered walkway, almost like buses at a bus station. We boarded and took off in only ten minutes, becoming arborne before reaching the first taxiway. The Shorts flies quite slow by today's standards at 200 mph and 10,000 feet altitude. Cabin noise level is good due to the special five bladed props designed for noise abatement. I was surprised to be able to stand fully upright (I'm 6'-3) without bumping things.

The data sources listed on the plan cover the first prototypes, the second of which is the subject of this article. Many books have articles and pictures of the SD3-30, so you can choose from lots of color schemes, or pick the colors of your favorite airline and take your own color pictures.

Very little had to be done to make the SD3- 30 into a good model subject. The stab area was increased slightly, but the dihedral was left unchanged. The wing airfoil was kept to scale also because I felt that a deep spar was necessary for strength in such a slender wing, plus it provided a husky center section to support the two motors rigidly. The wing looks too small at 75 square inches, but consider that many other surfaces are lifting too, such as landing gear legs, struts, and the whole top of that huge fuselage. The airplane is large for the Brown motors to pull unless they are well cranked up, so the 20cc tank is necessary for enough duration. The AMA minimum of 29 seconds is easily obtainable however. I prefer an underpowered model for this event because it looks more true-to-parent-aircraft when flying and usually gets more flight points..."

Shorts 330, Flying Models, April 1986.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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