Thursday, December 7, 2006

AV - Primary Gliders to the Rescue

I'm guilty of trying to get more people into the air, ideally in airplanes they've built themselves. But it's a tough row to hoe when the person is not a pilot. Toward that end I recently posted a message to the Fly5k mailing list about using a primary glider as part of basic pilot training.

In the message I said you'd have to work pretty hard to spend more than $300 building a primary glider. That generated a bit of mail :-)

Some folks didn't know what I meant when I said ‘primary glider' and a majority of those who did doubted one could be built for that amount. Telling them I was referring to the DFS's SG-38 or one of its variants, and sure they could, didn't help. In fact, each time I tried to clear up some point, such as why the type of wood you use isn't important, it seemed to made matters worse. It took a while for me to realize I was trying to explain the joy of old, comfortable shoes to folks who'd gone bare-foot all their lives :-)


Primary Gliders pre-date powered flight. Built with locally available materials, their only aviation-certified component was a healthy dose of common sense. Those early machines came in a variety of shapes, sizes and control schemes. The record shows some had the Right Stuff but most did not. After the Bicycle Brothers showed us How to Do It the variations in primary glider design became fewer. By 1914 the stick and rudder control system had become a de facto standard. World War One proved the practicality of that system over other methods and de facto became de juri. Weight-shifting, shoulder yokes and wing-warping were swept into the dust bin of history, to be re-invented with the advent of the hang-glider.

The present-day form of the Primary Glider originated in Germany during the 1920's and was introduced to the world through an article in the June, 1929 issue of National Geographic Magazine (*). The design continued to evolve (and still does) but was pretty much frozen by 1933 when the DFS published plans for the Model 38 ‘school glider.' ( DFS stands for Deutsche Forschungsanstalt fur Segelflug, the German Research Institute for Soaring Flight.)

Primary gliders proved so effective for imparting basic piloting skills that virtually every airmen of that era began their pilot training in an SG-38 or one of its variants. (‘School Glider' is ‘Shulgleiter' and is normally abbreviated ‘SG.') When you see SG.38 in a an old log book you'll know it means a primary glider, so don't be surprised if it shows three hundred landings but only five hours of flight. (To understand why, see: )

Plans for the SG-38 were made available to all and examples were built in nearly every country of the world. Many of these departed from the plans in one way or another, reflecting local flying conditions or the availability of materials. Among the many variants were struts instead of wire bracing, a wheel instead of a skid, fairings of various types (nacelles to some), steel-tube fuselage instead of wood - even a steel tube fuselage having a triangular cross-section (which is the type I prefer to build). Some variations even changed the primary's status from glider to powered flight by hanging a motor on the nose. (Anyone who has ever flown a primary gets a big grin on their face the first time they see an Aeronca C2. It's lineage is unmistakable.)

Unaware of the origin of the design or to distinguish a particular variation, Primary Gliders in different countries were often named after the first local builder or the first person to import a completed machine. The Kawasaki Model 24, for example, has struts and a nicely faired pod around the pilot but is otherwise virtually identical to the basic SG-38. Here in the States a primary is often called a ‘Northrup,' honoring the fellow who first imported one from Germany in the early 1920's. (I've not been able to identify him further, other than he was a scion of the Northrup seed company dynasty.) And while we may call it a ‘Northrup' even the most cursory inspection shows it to be the metric-dimensioned SG-38 cloned in inches and feet. (If you'd like to build one you will find plans and building instructions in the old Flying & Glider manuals, reprints of which are available from the EAA(**) for about ten dollars. Later issues of the Flying and Glider Manual depict some of the variants.)

(Note: Not to be confused with John K. Northrop, the brilliant aeronautical engineer whose broad spectrum of engineering innovations contributed significantly to Lockheed, Boeing, Douglas, North American and of course Northrop Aviation's incomparable flying wings.)

While details of their structure might change, the function of all primary gliders remains the same, which is to roar silently down their eight-to-one glide slope at a breathtaking thirty miles an hour. The pilot's task is to keep the wings level and to land straight ahead. Once the basics are mastered life becomes more interesting :-) (Riding the ‘hang' or slope-wind, you may stay aloft for hours, if you wish.)


Some people felt I'd overstated the case regarding the need for pilot training, that everything was just swell within the General Aviation community. As proof, they usually cited air-show revenues or attendance statistics to show there's no cause for alarm; surely no need to advocate anything as arcane as primary gliders.

Pilots and FBO's know otherwise. The reality of General Aviation is spiraling costs, X's on the ground, weeds springing up in front of hangar doors and a steadily growing number of empty seats at EAA meetings. But if you want statistics, I'll give you some.

According to statistics compiled by GAMA (***) the number of student pilots is well below the figure needed to replace our losses and has been for more than twenty years. The best proof of that is the fact the number of American pilots has shrunk by nearly twenty percent over the same period and the downward trend is not only continuing but accelerating. For more than twenty years we've seen the leaders of the aviation community try to turn things around with one ineffectual program after another yet our numbers continue to decline.

We need more pilots rather than more programs. I suggest it's time for each of us to roll up our sleeves and start training our own replacements. Primary gliders happen to be an inexpensive yet immanently practical means of doing exactly that.

A primary glider's role in life is to safely carry a nervous, over-controlling student to a rather bad landing after a flight rarely more than a minute in length. And to do that over and over and over again through the course of a long, sun-burned day until it is too dark to see and you are left alone to hump a sixteen foot wing into a fifteen foot trailer while a squadron of yahoos, surely the worst crop of pilots to ever come out of Mrs. Edward's fourth-grade class, dances around you slightly insane with the thrill of having actually flown. Not as a lectured-to passenger in a 182 smelling of the last fledgling's vomit but as Pilot in Command on a never to be forgotten solo flight through the eery isolation of the air, and well above the land.

Primary gliders are inexpensive and easy to build. And for a good reason. A well maintained primary glider can withstand thousands of student landings but over time it becomes a collection of patches and repairs and accumulated wear until you bite the bullet, condemn the thing to the wood stove and build another. But rarely alone. By seasoning a barrel of patience with a pinch of wit you'll be surprised at the number of kids more than willing to abandon the tube for the shop. Once built, their labor earns them Head of the Line privileges in its use.


Primary gliders alone are not the answer. But they have the potential to be a big part of it. Students with primary glider experience are safe to solo a powered trainer in a fraction of the time needed by students with no glider training.

In modern-day America the majority of people who would like to become pilots can not afford to do so. Indeed, the high price of a private pilot's license virtually guarantees the demise of General Aviation as we know it. Primary Gliders are one means of skewing the odds in our favor. They can put more pilots into the air at less cost than existing methods of pilot training. The proof of that is an historical fact and as such, is worthy of thoughtful consideration.


(*) ‘On The Wings of the Wind,' Seipen, Howard A., National Geographic Magazine, June 1929, pgs 751 - 780

(**) ‘Building Instructions and Plans for the Northrop Glider,' Weston Farmer, 1930 Flying and Glider Manual, pg 53

Reprints of the 1930 Flying and Glider manual are available from the EAA. Ask for Item Number F14168. Price is $6.95 plus shipping & handling. EAA Mail Orders PO Box 3086 Oshkosh, WI 54903-3086 or call: 1-800-843-3612

(***) General Aviation Manufacturers Association 1400 K Street, NW Washington, DC 20005

The opening image is of a primary glider over Box Hill, NSW, Australia, circa 1940.



flybynightkarmarepair said...

I'm curious why, if they are such a good idea, they died out pretty quickly after WWII, even among nations with a pretty strong glider tradition, and the stationary winches to launch them without either a specialized site or a big ground crew? Great Britain in particular invested quite a lot in them AFTER WWII, only to let them rot to bits by the time the Beatles were tuning up, if not before.

Could it be they were, in the end, not as productive a training environment as a powered trainer?

Much the same question can be asked about "penguins". If they were truly cost-effective, why did they dissapear almost totally after the FIRST World War?

I'd like to believe in both of these approaches, and I may build a "penguin" as my son gets a little older, but frankly I can find an airport easier than a place where I could run a "penguin", to say nothing of a suitable hill to fly a primary glider.

flybynightkarmarepair said...

I'll amend my previous comment: there is one country that still believes in primary gliders: Lithuania. A web page I can no longer find showed how they used a truck driven endless loop winch setup at one school to launch these gliders.

And the Hang Glider folks, another group were Mortality is exceeding Replacement, are looking at Scooter Towing as a way to get more people into their sport, even in flatland sites like Kansas.

FNG10-66 said...

I was thinking about asking your learned opinion of the "BUG",Basic Ultralight Glider, for which plans are available FOI "free on Internet", and walla, you put up a post on the subject. It looks like the SG38 done up in aluminum tubes, but you probably already know about it, and I'm a troublemaker for bringing it up...

flybynightkarmarepair said...

FNG10-66 said...

I was thinking about asking your learned opinion of the "BUG",Basic Ultralight Glider, for which plans are available FOI "free on Internet", and walla, you put up a post on the subject. It looks like the SG38 done up in aluminum tubes

The BUG/GOAT designs have a different mission, and both higher cost and higher performance than a Primary Glider. High enough performance to potentially get a novice in trouble. And perhaps 10X the cost of a SG-38 built with materials from Home Depot.

Anonymous said...

I'd like to address the questions raised by "Flybynight" if I may, having just returned from a bungey-launching session on the Wasserkuppe (featuring an SG-38):

It is absolutely correct that two-seat, dual-control trainers--whether powered or gliders--provide more productive teaining environments than primary gliders or "penguins" ever could. During the heyday of the Primary, this hadn't yet been accepted, but was nonetheless true...people learn faster when they have along for the ride someone who can demonstrate the finer points, analyze and critique errors, etc.

However, it must also be said that nothing can match the economy of the Primary glider! Therefore, if your highest priority is to get people into the air and actually flying as pilot-in-command, while holding costs to the absolute minimum, the Primary makes sense.

To put my comments into context, I have been an active glider instructor for the past thirty years (and also fly powered airplanes, having served as Captain on A320, B757, B767 and B777 aircraft.) Never once in my career have I ever regretted learning the basics first--and best--in gliders.

By the way, the Vintage Soaring Association often launches an SG-38 on flat ground--no hill required. (Flights are a bit shorter, of course, but the purpose served all the same.)

Anonymous said...

quite interesting article. I would love to follow you on twitter. By the way, did any one know that some chinese hacker had busted twitter yesterday again.