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Wings of Madness

Tour the Demoiselle

Brazilian aviation pioneer Alberto Santos-Dumont dreamed of making flight accessible to the general public. In 1907, he unveiled a design he hoped would meet this goal: a tiny aircraft he called the Demoiselle, or Damselfly. Weighing only 300 pounds, its airframe was compact and easy to build, and served as a viable starting point for budding aviators. By 1910, Popular Mechanics magazine published plans for the latest model of the aircraft with high praise, inspiring a number of early enthusiasts to build their own. In this audio interactive, explore a replica of a 1909 Demoiselle #20 and discover the unique design features of the world's first ultralight sport plane.—David Levin

Engine
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Detroit Aero Engine
On this example of the Demoiselle #20, this engine is called a Detroit Aero Engine. And it came out the same time as this Demoiselle from 1909. In France they would have used Darracq aircraft engines. They would have used another example, too, the Dutheil-Chalmers, I believe is how it was pronounced, both about the same power, both about the same weight. But if you were to build a Demoiselle in America, well, this is the type of engine you would have put on it—the 1909 Detroit Aero Engine. It had an rpm of about 1,200 rpm, which is common for most of the engines of that period. It only weighed 110 pounds. It was air-cooled and provided power at about 30 or 35 horsepower.



Prop
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Propeller
The design of the propeller is pretty traditional to the aircraft of their day. It had a sort of a graceful "S" look to it. If you could draw a very shallow S, it had a very nice curve. They were very slow-turning propellers. Today we have these little toothpick props that turn up thousands of rpm. But back then a slow-moving propeller was much more efficient. And the propeller [was] made of a variety of woods such as mahogany and birch. A very efficient propeller. The only drawback with the Demoiselle was if you notice where the pilot sits in some of the other photos, you'll see how close the propeller is to the pilot's feet, which is something you always are aware of when you're flying one of these little airplanes.



Wing Structure
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Wing Structure
One of the things that the early designers were trying to come up with were ways to make an airframe strong but make it light. One of the woods they experimented with was bamboo. Santos-Dumont used it quite liberally in his designs of his Demoiselles. This example, as you can see, is all held together with bamboo. You didn't use glue or screws because the bamboo was very frail around the areas where it needed to join to another piece. You'd lash it together. Sometimes I felt like Robinson Crusoe building this airplane. You can see the liberal use of brass wire, which was used originally to clamp all the pieces together. Then the fabric is just basically laid over the top, stitched in between the ribs. And then it was laced to the front with that little baseball stitch style that you see.



Landing Gear
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Main Landing Gear
The landing gear of the Demoiselle was pretty standard fare for its day. The frame is connected to the gear directly. Very light, very frail wheels, so you had to land very gently. They're basically bicycle wheels. And the advantage of where the pilot sat is where he could stretch out and use his hands to stop the airplane. It's always a good thing to be able to do that if you're landing kind of quickly. And you'll notice that Santos-Dumont usually wore gloves when he flew the airplane, for protection when he grabbed the wheels to slow down.



Tail Assembly
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Tail Assembly
In this picture we're looking at the tail of the airplane, which is sort of unique, because it operates as a rudder and as an elevator all in one assembly. It's built of bamboo, much like the rest of the airplane. Trailing edge is nothing more than a piece of wire connected to each of those pieces of bamboo you see sticking out of the fabric. And this would be used for your pitch and steering of the Demoiselle.



Cruciform
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Cruciform
A closer look at the tail shows what is known as the cruciform, a design that Santos-Dumont came up with, which is sort of like a universal joint. The rudder and the elevator were connected together. And this is a hinged affair where, when you operated the controls in the cockpit, you could make the tail either move up and down along a hinge on the horizontal axis, and along the vertical axis you could operate it from left to right for steering. A very simple affair, very efficient, and, of course, you want to keep it very light and strong. And this design worked perfectly for this airplane.



Bamboo Frame
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Bamboo Frame
One of the significant structures of the Demoiselle is the triangular fuselage made of three bamboo poles. You can see the use of the bamboo, and also the concept of incorporating some steel into the structure to give it some strength, the steel tubes that form the triangular fuselage. You had a structure much like a bridge, a very, very strong, lightweight, resilient structure. And it was very, very successful for this particular airplane. A little detail note that you'll notice in between what are known as nodes, the little bumps on the bamboo poles, you'll see some brass wire wrapped. This wasn't for decoration. This was used to keep the bamboo from splitting along its length.



Tail Skid
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Tail Skid
Santos-Dumont tried several different designs of the Demoiselle. Some of them had a tail wheel. Some had a skid and a tail wheel. This example of the #20 has just the tail skid, and it resembles a little bit of an umbrella handle, if you will. Made of steel tubing just heated up and bent round, and then braced with some wire to keep it from breaking off of the airplane. You'll notice that there's a little structure just before the curve on the bottom. And that's fastened to the frame so that as the airplane rolls forward it wouldn't pull the tail skid off.



Fuel Tank
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Fuel Tank
This is a picture of the gas tank for the Demoiselle. It didn't hold very much fuel, but you weren't planning on flying very far. They were very small tanks. The copper line that's coming down from the front of the tank is the fuel line. That curled look to it is not just for Jules Verne style or anything. That is actually very practical and very useful. And that was used to dissipate the vibration from the engine so that the fuel line wouldn't crack. And by curling it like that, you added a lot more life to the fuel line.



Pilot's Seat
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Pilot's Seat
We're looking at the cockpit, if you will, of the Demoiselle #20. And here is the canvas seat that the pilot would sit in. It's simply a piece of canvas that's laced to the sides of the lower bamboo poles. No safety belts in this airplane. And you would just make yourself as comfortable as you could in there. There were a couple of little stirrups up front for your feet to rest on. But that was all there was to the seat.



Elevator Control
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Elevator Control
One of the four controls of the Demoiselle is the elevator. This stick that you see in front of the canvas seat is basically a stick that moves forward and backwards. And that would operate your pitch control and operate the cruciform tail, where you would pull back on the stick, and you would climb; push forward and you would dive. Very, very simple. There's a little black button you'll see on the top of the stick. And this was used to turn the engine on and off. And all you do is push that button. It was a spring-operated switch, so it'd briefly interrupt the power to the engine so you could slow down.



Rear Control Stick
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Rear Control Stick
This little stick that was behind the pilot would aid in banking the airplane into the direction you wanted to go. To activate it you had a small pocket sewn into the back of your leather jacket. And some of the pilots even used a strap, a leather belt to go around their waist to not only keep that pocket secure with the stick but also to aid in moving it. So as you leaned in the seat from side to side, you could bank the airplane. Lean to the left, you banked to the left; lean to the right, and you would bank to the right.



Rudder Control
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Rudder Control
The rudder was operated simply by this tiny wheel that was welded on to the bracing of the interior section, if you will, of the cockpit. It was a simple little device. It operated the cruciform tail to steer the airplane. This would move the tail left and right to make turns. As you pushed forward, you could make a right turn. As you pulled back, you could make a left turn.



Rudder Control
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Throttle Toe Clip
On the Demoiselle there were two ways to operate the throttle. One was the button that was on top of the elevator stick, and the other way was with this throttle toe clip. This clip would connect to your left shoe, into the toe. And the wire that you see would go up to a spring-loaded affair which would connect to the carburetor. And to operate the throttle, it was a little bit like operating a gas pedal in your car. As you press forward, you go faster, and as you release, you would go slower.



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