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Unmanned Ornithopters

See also the links at your left for micro-sized and rubber-band-powered ornithopters. This page pertains to engine-powered and electric ornithopters that are too small to carry people and too large to be considered micro air vehicles. Many of these are radio-controlled (RC) ornithopters. Most of the recent RC ornithopters are powered by an electric motor and lithium-polymer rechargeable batteries. Flying an RC ornithopter is similar to flying an RC airplane, and both require a similar degree of skill. A throttle stick on the controller varies the flapping rate. This allows the ornithopter to climb or descend. Moveable tail surfaces are used for steering. Some RC ornithopters have a bird-like tail, but if you see airplane-like control surfaces, it is probably a more efficient flier. The timeline below shows the development of this technology starting with the first successful ornithopter in 1870.


 
     1870. Gustave Trouvé flew an ornithopter powered by compressed air. There are no pictures of that first ornithopter, however. The ornithopter shown here was flown in 1890. Twelve gunpowder charges were fired successively into a bourdon tube to flap the wings, an unusual type of internal combustion engine. The ornithopter flew 70 meters in a demonstration to the French Academy of Sciences.
 

 
 

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. Vincenz Chalupsky built a series of ornithopters that could be powered either by compressed air or carbon dioxide. These ornithopters had a birdlike appearance.

 
 

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.
 

 
seeking photo

 
  1935. In Walden NY around 1935-1936, Early Bird pilot Harry D. Graulich successfully 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.
 


 
     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 customers 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. I 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.

Folding or Articulated Wing Ornithopters


 
         1930s. Erich von Holst experimented with various bird and dragonfly ornithopter configurations. Some of his rubber-powered ornithopters achieved a very high level of realism. In this one, the outer wing panels were hinged, to more closely mimic the movement of a bird's wings. However, the wings could not truely fold by way of overlapping feathers in the way that a real bird's wings do. The feathers you see in the picture are merely cosmetic.
 
     

 
  2004. Jonathan Howes constructed a bending-wing ornithopter, functionally similar to von Holst's ornithopter shown above, but much lighter for indoor flying. It achieved flight times of 4 or 5 minutes, which is comparable to conventional membrane-winged ornithopters. Nice job!
 

 
  2011. Festo AG announced a radio-controlled ornithopter with bending wings. They are similar in function to the bending wings of Erich von Holst, except that the wing twisting (not the bending action) is driven by a servo motor in each wing. This allows the amount of wing twist to be adjusted on the fly.
  1997. My VS1 ornithopter was the first successful implementation of an ornithopter with true variable-area wings. Instead of multiple feathers, I used a simplified design with just two overlapping plates. The plates correspond to the primary and secondary feathers of a bird's wings and produce a very life-like wing-folding action.

I first began working with ornithopters in the 1980s. At that time, there was a group called The Ornithopter Modelers' Society. 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. The first engine-powered ornithopters already existed half a century earlier! I am still picking up new fragments of ornithopter history, so if you find out about any successful projects that aren't described on these pages, please let me know!