This page describes the complete history of unmanned ornithopters, or flapping wing aircraft. I have described the manned ornithopters on a separate page. It is important to understand that the record of flapping-wing devices has not been well-preserved. It is an obscure topic to begin with. The idea has been frowned upon in the field of aviation. Many of the researchers either fail to receive widespread publicity, or deliberately sequester their work. I have spent decades researching this subject, and I present here the best possible summary of ornithopter history. However, I am certain that some significant research took place long ago, of which we have no record. From time to time, findings of this sort still come to light.

As far as I can tell, the first ornithopters were flown in France, in the 1870s. Keep in mind that this was almost a hundred years after the invention of the hot air balloon. People were looking for another way to fly, and they drew inspiration from the flight of birds. Bird flight was the example that proved a heavier-than air method of flight could exist. The early experiments with unmanned ornithopters were therefore intended to pave the way for human flight.

However, the unmanned ornithopter is a fascinating endeavor in its own right. Today, unmanned ornithopters provide an excellent educational opportunity for students, as well as great enjoyment for hobbyists. In 2007, many people witnessed what they thought were robotic dragonflies, being used by the United States government to spy on civilians. Whether or not that was the case, ornithopters can indeed be used to carry cameras and other payloads. They have been used in biological field studies, to chase birds away from airport runways, and potentially they could be used to transport various items from place to place.

The first experimental ornithopters were powered by rubber band, just like some of the models that hobbyists can build today. The leftmost illustration shows an ornithopter that was flown by Jobert in 1871. It was powered by a stretched rubber band turning a crank. In the following year, Jobert built a biplane (four-winged) ornithopter with the twisted rubber band motor more common today. The use of four wings was a clever innovation that reduced the amount of torque needed to flap the wings. The other ornithopters shown here were built by Alphonse Penaud and Hureau de Villeneuve, respectively, in 1872. (These were described by Octave Chanute, in a 1891 article that would become part of his book, Progress in Flying Machines.)

To clear up a few misconceptions: It is sometimes claimed that Penaud was the first to build a successful rubber-powered ornithopter, in 1874. Obviously, whoever made that statement did not know about the earlier work. William Hudson Shaw's biography of Lawrence Hargrave mentions a rubber-band-powered model flown in 1858 by Pierre Jullien. When I contacted the author for more information, he clarified it was actually a rubber-band-powered model airplane, not an ornithopter.

In 1874, Victor Tatin devised a more complicated crank mechanism that actively drove the twisting of the wings. His ornithopter shown here is on exhibit at the National Air & Space Museum in Washington. Most of the mechanism was fashioned from bent wire, and it is quite interesting to examine up close. A similar mechanism was used by Pichancourt in his toy bird, "l'oiseau mécanique". This was perhaps the first commercial venture involving ornithopters. Pichancourt is shown at right with his lovely assistant and the biggest rubber-powered ornithopter I have ever seen! He must have needed a huge bundle of rubber to flap those huge wings.

In fact, the thickness of the rubber band has to increase faster than the scale of the ornithopter. If you double the wingspan and every other dimension, the rubber band needs to be more than twice the thickness of the original. This could be corrected by using some sort of gear reduction to amplify the torque of the rubber band. However, that is not so easy to do. Lawrence Hargrave, working in the 1890s, discovered an easier solution, which many people after him have adopted. To reduce the torque requirement, he made the flapping wings smaller and provided a large fixed wing. Two examples are shown below. At left is one of Hargrave's ornithopters. The center photo shows an ornithopter built by Alexander Lippisch.

Alexander Lippisch led a group of aviation students during the 1930s. He and his students built many large ornithopters powered by rubber band and by internal combustion engines. The science of aeronautics had advanced greatly since Hargrave. These ornithopers had better airfoils and more efficient flappers, even though the flapping wings remained comparatively small.

Erich von Holst experimented with various bird and dragonfly ornithopter configurations in the 1930s. His work included experimentation with biplane wing phasing and hinged outer wing panels. Some of his rubber-powered ornithopters achieved a very high level of realism, as in the example shown above. In this one, the outer wing panels were hinged, to more closely mimic the movement of a bird's wings. He used pulleys to increase the torque.

Indoor ornithopter contests began in the 1930s. A model airplane club called the Chicago Aeronuts was holding various contests for the indoor flying of model airplanes. For some extra challenge, they decided to add ornithopters to the list of events. Ed Lidgard's design shown here could be built from magazine plans, and many of the rubber-band-powered ornithopters built over the subsequent decades followed a similar pattern. Eventually the ornithopter event became part of the national model competition arranged by the Academy of Model Aeronautics.

In the 1980s, it was found that biplane ornithopters had a huge advantage in these indoor flying contests. With monoplane ornithopters, much energy was lost at the end of each wingstroke, when the crank went through its "dead center" position and snapped forward without doing any useful work. With four wings, you can set it up so one pair of wings is in mid-stroke, maintaining a load on the crank, while the other pair is at the end of its stroke. The cranks don't reach dead center at the same time, so the crank doesn't snap forward, we can harness the energy of its full rotation, and the smoother flapping motion allows overall weight reduction.

By coupling the upstroke of one wing to the downstroke of another, two other benefits were achieved. First, the upstroke could procede more slowly, so the wing could continue producing lift during the upstroke. Second, the lift on that wing would partially offset the force required for the other wing's downstroke, reducing the overall torque requirement.

Another modification was to move the stabilizer to the front of the model. With the flapping wings at the back of the motor stick, the stabilizer could be positioned directly above the motor stick and in clean air where it could function more effectively as a lifting surface.

With these innovations, ornithopter flight times increased from around four minutes, to the current record of 21 minutes, 44 seconds held by Roy White. Successful competition models are extremely light-weight and delicate. Careful adjustments must be made to maximize the flight time without hitting the ceiling. Perhaps as you refine your ornithopter skills, you will be able to log some impressive flight times of your own.

The rubber-band-powered ornithopter also offers a range of interesting projects, aside from duration contests. Shown above: Ken Johnson's lifelike butterfly model. John White's ornithopter in which the tail moves as well as the wings. Albert Kempf's dragonfly using a geared rubber band motor and foam wings.

Internal Combustion

There was a group called The Ornithopter Modelers' Society, founded by Patrick Deshaye in 1984. It was a group of hobbyists around the world, who made use of Deshaye's quarterly newsletter to exchange ornithopter designs and ideas. The society was instrumental in rekindling interest in ornithopters and accelerating their development. Some of the members were interested in indoor ornithopter competition, while others were trying to figure out how to build an ornithopter powered by an engine instead of a rubber band. We all thought it had never been done. Gradually, I began to uncover some of the historical information that you see here.

For a long time, we thought Gustave Trouvé had built the first successful ornithopter. Recently, with the help of biographer Kevin Desmond, we were able to sort things out a bit. In 1870, Trouve made an ornithopter powered by compressed air. I am not sure if it actually flew, and we don't have any pictures of it. The ornithopter shown here was flown in 1890, not 1870 as previously thought. Twelve gunpowder charges were fired successively into a bourdon tube to flap the wings. The ornithopter flew 70 meters in a demonstration to the French Academy of Sciences. Therefore it appears this was not the first ornithopter to fly, but it was the first to use a type of internal combustion engine.

		1890. Lawrence Hargrave built some ornithopters powered by steam and compressed air. The ornithopter shown here is about 2 meters long and hangs in the National Air & Space Museum. Hargrave used a rear fixed wing, like the tail of a bird but much larger in size and carrying more weight. This eliminated the need for gear reduction and therefore simplified the construction.
		1930s. Alexander Lippisch and members of his NSFK group in Germany constructed a number of piston-driven ornithopters. One of Lippisch's ornithopters had a 3 meter wingspan and weighed 1950 grams. Using a 4 cc petrol engine, it made flights up to 16 minutes. Lippisch also designed the Me 163 rocket-powered fighter aircraft.
		1935. Vincenz Chalupsky built a series of ornithopters that could be powered either by compressed air or carbon dioxide. These ornithopters had a birdlike appearance.
seeking photo		1935. In Walden NY around 1935-1936, Early Bird pilot Harry D. Graulich flew in tethered flight an engine-powered ornithopter with about a 4.8 meter wingspan. It was powered by a four-cylinder, air-cooled engine.
		1958. Percival Spencer constructed a series of engine-driven ornithopters in the shape of a bird. They ranged in size from a small 0.02-engine-powered ornithopter to one with an eight-foot wingspan. Spencer is also noted as a pioneer pilot and the designer of the Republic Seabee amphibious airplane. He also designed a toy, called the Wham-O Bird, which introduced thousands of children to the idea of mechanized flapping-wing flight.
		1960. Spencer collaborated with Jack Stephenson to build the Orniplane. This was the first radio-controlled ornithopter. It now resides at the New England Air Museum in Windsor Locks, CT. Spencer sought funding to build a manned version. The biplane wing configuration was to provide a smoother ride for the pilot and also protected the sensitive early radio equipment. Reportedly, Spencer's colleague Dale Anderson later converted one of Spencer's Seagull ornithopters to radio control as well, using the improved radio equipment of the 1980s.

Electric Power

In the end, it became more practical to use electric motors, instead of internal combustion engines, to power at least the unmanned ornithopters. Electric motors simplify the construction and make the ornithopters more convenient to operate. The power-to-weight ratio is comparable to internal combustion engines.

		1984. Valentin Kiselev's radio controlled, tandem-wing ornithopter is shown. This ornithopter was powered by an internal combustion engine. Kiselev also flew some of the first electric ornithopters.
		1986. Despite being underpowered, Paul MacCready's QN pterosaur replica achieved new levels of realism and demonstrated active stabilization methods like those used by birds and other flying animals. The otherwise-unstable ornithopter had an onboard computer to keep it from going into a spin. The flight path was controlled by radio. It had a wingspan of 18 feet.
		1990. Horst Räbiger's radio-controlled ornithopter, EV7, was a technical marvel, using thick-airfoil wings and a pneumatic spring to provide extra power in the downstroke. In this ornithopter, the twisting of the wings was actively driven by the motor, whereas most ornithopter wings twist in response to aerodynamic forces.
		1991. James DeLaurier and Jeremy Harris flew a large radio-controlled ornithopter, powered by internal combustion. The wing appeared similar to the EV7's, but it used passive aeroelastic wing twisting. The news media inaccurately reported this as the first engine-powered, radio-controlled ornithopter, at a time when few people knew about the prior successes.
		1998. Albert Kempf's Truefly ornithopter used electric power and actively twisted foam wings. Kempf reported that this system was very energy-efficient. Kempf went on to build some other ornithopters using a similar mechanism. One of the ornithopters was made to resemble an eagle and was more realistic looking than the initial design shown here.
		1998. Sean Kinkade's Skybird, based somewhat on the Spencer Seagulls and using a 0.15 methanol-fueled engine, was an attempt at small-scale commercial production of an RC ornithopter. Smaller, electric versions were later offered. Unfortunately, many would-be enthusiasts paid their money and never received the product.
		2000. Some applications for ornithopters rely on their resemblance to real birds. Intercept Technologies experimentally used radio-controlled ornithopters for bird control. Styled to look like birds of prey, the RoboFalcon ornithopters were used to chase flocks of birds away from airports, where they can pose a threat to aircraft.
		2003. Neuros Company of Korea introduced the first commercially mass-produced RC ornithopter. Called the Cybird, it was sold in two different versions. The Cybird P2 had a 39" wingspan and three-channel radio control. The later-introduced Cybird P1 had a 29" wingspan and two-channel radio.
		2007. Robert Musters began a series of RC ornithopters with foam, actively twisted wings. The appearance of these ornithopters is close to that of a real bird and they are being offered for use in bird control at airports.
		2008. Nathan Chronister built this four-winged RC ornithopter for a demonstration at IIT Bombay. It represents a concept for a manned ornithopter at 1/10th scale. The wingspan is 36 inches. The four-winged design gives this ornithopter excellent slow-flight capabilities, and it can even be configured for hovering flight.
		2013. The S-1 Robotic Bird, developed by Nathan Chronister and marketed by BirdKit.com, takes advantage of new servo technology developed by Hitec to mimic the muscles of a real bird. This new paradigm allows total control over the wing movements, in contrast to the typical crank mechanism with its set range of motion.

Micro Air Vehicle (MAV) Ornithopters

Micro air vehicles, also known as MAVs, result from the US military's interest in miniature spying devices. The Defense Advanced Research Projects Agency (DARPA) has heavily funded some of these projects. Small radio-controlled ornithopters can carry a camera payload for spying inside buildings. The ultimate goal is to produce an ornithopter so small and lifelike that it can pass as a real insect or small bird, going unnoticed as it performs its deadly mission. With recent advances in hobby radio control products, now you can build your own micro-sized ornithopters and spy on your neighbors.
 

		1970s. The US Central Intelligence Agency developed its first tiny ornithopter for spying. It was powered by a gas-producing chemical reaction through a combination of flapping wings and jet propulsion. It had a 9 cm wingspan, weighed only a gram, and flew for up to 60 seconds. It was supposed to be controlled by some kind of laser guidance system, but that turned out not to be very effective.
		1997. Nathan Chronister built a four-winged ornithopter that could hover using a vertical wingstroke. This is similar to dragonflies, but different from the hovering ornithopters that would follow. It was not radio controlled but demonstrated a stable hovering flight.
		2000. The MicroBat, developed by Aerovironment and Caltech, was the first micro-sized ornithopter resulting from MAV funding. It had three-channel radio control and used one of the lithium-polymer batteries which had just become available.
		2002. Mentor, developed at University of Toronto, was the first hovering ornithopter with radio control. (There was hovering prior to this, but it was not radio controlled.) Hovering is important for MAV applications that require maneuvering in tight spaces.
		2003. The Luna ornithopter model kit introduced a simple scissor-wing design, which simplified construction and led to a proliferation of four-winged ornithopters. (The Ornithopter Zone model kit was based on 1993 plans.)
		2005. Yusuke Takahashi converted the Luna to remote control, and discovered that with the addition of an elevator control function, the already slow-flying design could be made to hover. Takahashi has built many other micro-sized RC ornithopters with very creative designs.
		2006. At the first International Micro Air Vehicle Competition, university teams competed to see who could perform the most pylon circuits with the smallest ornithopter. This annual event is held in a different location each year and also includes rotary-driven MAVs. (Utah entry is shown.)
		2006. Delfly, developed at the Technical University of Delft and Wageningen University, is able to transition between hovering and forward flight. These ornithopters also carry a small video camera. The live images are analysed by a computer on the ground, giving Delfly the capacity for autonomous navigation. (The newest version as of 2013 has an onboard visual navigation system.)
		2007. This ornithopter developed by Nathan Chronister can hover and perform aerobatic maneuvers. This ornithopter achieved a MAV benchmark because it is the size and weight of a real hummingbird. The ornithopter weighs 3.3 grams and has a 15 cm wingspan.
		2007. Currently the world's smallest radio-controlled ornithopter, this one constructed by Petter Muren has a wingspan of 10 cm and weighs only 1 gram.
		2010. Aerovironment's Nano Hummingbird, while not especially small, was a huge breakthrough in MAV ornithopter research because of its gyroscopically stabilized flight without any tail surfaces.