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Concept: Can a Long "Longster" be Built as a Legal Part 103 Ultralight?

By Oscar Zuniga, EAA 237232

The Henderson Longster (see adjacent black and white photos). Note cable bracing of the wing using cabane king post. Long increased the size of the rudder, presumably because this king post arrangement blanked airflow to the tail more than the mid-wing version. A 1-gallon fuel tank is visible as a “nub” between the king post members in the above photo.


The Anzani Longster. Note the strut bracing of the mid-wing, the distinctive balanced Longster rudder, and the rigid landing gear setup. Long’s landing gear design also included an option with rubber doughnuts or springs, but those aren’t needed when operating off grass. Today’s pneumatic tires would help in that department as well, saving the weight and complexity of springs or shocks.


While many of the framing details and construction techniques used in the Longsters are common to them all, there are significant differences. For example, the Anzani Longster above shows that the wings are strut-braced, while the Henderson version has a “king post” of sorts, with aircraft cable bracing of the wings. The landing gear design is similar, as is the triangular-section empennage framing. The replica shown above is from the Oregon Aviation Historical Society in Cottage Grove.

The 35-hp Anzani three-cylinder radial engine.

This Henderson engine resides in the Power of the Past Museum at the Thomasville Regional Airport. This is part of the personal collection of the James Dekle Family of Thomasville, Georgia. It is their desire to preserve vintage aircraft engines for the education and enjoyment of young and old for generations to come. The best time to visit is during the annual Thomasville Fly-In the second weekend in October. James Dekle is usually at the airport on Sunday afternoons, or you can call him at 229-226-3010 to meet him there at other times. ljdekle@rose.net

Long’s Harlequin engine. Open valves and bed mount. Very easy to cowl and fair into the airplane’s lines. Air filter and carb heat, not installed here, are absolutely recommended.

UltraVair 1/3 Corvair conversion.

Oscar Zuniga is a private pilot and experimental aircraft builder who has contributed to CONTACT! Magazine various times (see Issue #57, “A New Wing for the KR”). He owns, maintains, and pilots Pietenpol Air Camper NX41CC, and he operates it under the sport pilot regulations. He is modest when reporting his 500-plus hours as pilot in command, but is happy to proclaim good fortune with the variety of different planes he’s flown. His current project is an M-19 Flying Squirrel, featured in the premier issue of Experimenter electronic newsletter.

As I reached my 53rd birthday, I began to develop hypertension and became concerned about keeping my third-class airman medical certificate. Since then medication has successfully controlled my blood pressure, but I began planning for a transition to flying as a sport pilot with an eye farther down the path of life. Without much care for buying a manufactured, assembled, or even an “ultralight-in-a-box” that I would assemble myself, I took a serious look at the various scratch-build ultralights. A good one is the Legal Eagle, and another that I considered was the Affordaplane, but my mind kept going back to a nifty little design from the 1920s: Les Long’s Longster. Although not a legal Part 103 ultralight as conceived and flown back in its day, I believe that the design lends itself to today’s ultralight construction techniques and can be brought forward 85-plus years into the 21st century.

Back in 1930 or so, Oregonian Les Long designed a series of light-sport aircraft he named Longsters. The Long Longster, the first in the series, was designed for simple, affordable, safe sport flying. The original Longster reportedly flew well but had “irritating habits” and was dismantled. The second version had a strut-braced mid-wing and was powered by the 35-hp Anzani three-cylinder radial (see photo) and flew so well that Long was asked to write a story about it for Modern Mechanix and Inventions magazine. Like the other stories from that era that were later compiled into what are called the Flying and Glider Manuals (still available through EAA, or call 800-564-6322. Note: The Longster story appeared in the 1931 issue), the story included technical information, construction tips and sequence, and drawings that were detailed and complete enough to allow an experimenter to construct one. The Anzani Longster had a wingspan of 27 feet, length of 18 feet 3 inches, empty weight of 425 pounds, top speed of 91 mph, “landing speed” of 32 mph, and a range of 120 miles. Certainly not an ultralight.

Long was also asked to write about his next version, the Henderson Longster (see top photo), which was a high-wing adaptation using a king post-style cabane to provide cable bracing for the wings and a bit better protection for the pilot in the event of a rollover.

The Henderson was an inline four-cylinder motorcycle engine that weighed somewhat more than the Anzani, so Long redesigned the fuselage and structure to reduce weight to compensate for the heavier engine. The construction drawings and details were published with the story of the new version since it was considerably different from the Anzani version. Each wing panel length was increased 3 feet. However, the wing roots butted together at the cabane king post, resulting in a new net wingspan of 30 feet with most other key dimensions remaining the same. This might be important to approaching an ultralight configuration, considering the empty weight dropped to 325 pounds, top speed was reduced to 75 mph, “landing speed” was 25 mph, and according to the article, Long flew it with a 1-gallon fuel tank. Glide angle was stated to be 12-to-1, not surprising given the wingspan and the 50-inch chord Clark Y airfoil. Starting to sound more like an ultralight?

The fourth version and the most interesting was the Harlequin Longster. In continuing his quest for simple, affordable flying, Long decided to design and build his own simple two-cylinder opposed-twin four-stroke engine that used readily available Harley Davidson 74-inch cylinders and other readily available parts.

The result was the Harlequin engine, also written up in the Flying and Glider Manuals. It weighed 90 pounds, put out 30 hp at 2650 rpm, and used a bed-type mount with carburetor below the engine. Comparable powerplants from today, such as the 1/3 Corvair Ultravair or one of the various 1/2 VW engine conversions that are available would be a perfect match for the Longster. The Ultravair was covered in traditional detail in CONTACT! Magazine, issue No. 75. But even though there may be other viable two-cylinder engines to consider, my focus with this concept is with the 1/3 ’Vair.

The Ultravair (adjacent) is fabricated by cutting and modifying the stock six-cylinder case, crank, cam, and heads of the air-cooled boxer-style Corvair engine and providing new cover plates, oil pump, and a simple magneto for ignition. The conversion weighs 80-85 pounds and puts out 35 hp. It also takes advantage of a four-point bed mount and so should be the perfect match for the Longster airframe, once it’s suitably lightened to get it into the 254-pound limit mandated for Part 103 ultralight operation.

The 1/2 VW numbers are about the same, but it mounts differently, which could work out to either being good or bad. Either way, it’ll be different. Since the modern options and Harlequin engine are of comparable weights, approximately 80 pounds must be eliminated from the Longster airframe to get it into ultralight trim. I believe this is achievable using aluminum tubing, gussetted joints with blind-rivet construction, and the lightest fabric covering available. Various other materials are available today that can provide equivalent strength and safety while providing the necessary weight savings. In addition, the wingspan can be reduced slightly without too much performance reduction if it’s determined that more weight must be eliminated.

In conclusion, it is my premise that the same factors that drove experimenters back in the 1920s to search for simple and affordable ways to get into the air are driving today’s experimenters who are unwilling or unable to build or buy large or expensive airplanes or kits.

I plan to develop my concept of modernizing the Les Long Longster using today’s engineered materials and a proven powerplant with the objective of creating the Ultravair Longster (with apologies to Mr. Long) and of eventually constructing such an ultralight vehicle and testing it.

To learn more about Les Long's experimentation with light aircraft to improve their performance, read "Some Remarkable Experiments in Lightplane Performance," from the November 1935 issue of Popular Aviation, the predecessor to FLYING magazine. Reprinted by permission from FLYING magazine.

View some historical photos of Les Long's Longster along with some construction drawings from a 1931 Flying and Glider Manual article that Long wrote about building the Longster.

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