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EAA Chapter 108
Fort Walton Beach, FL
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1976 Lewis Turner Blvd
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Richard Sohn
Unicorn Autogyro
 
Richard's Autogyro
 
Richard's Autogyro
  
 

Builder: Richard Sohn 
Email:  unicorn@aic-fl.com 

Richard describes his Unicorn autogyro as follows: 

The UNICORN autogyro is the only autogyro, and possibly the only aircraft, in the world flying with a true ducted fan for propulsion. 

The UNICORN was designed and built in a homebuilder's environment. It turned out to be very special in many respects. First of all, it meets FAR103 requirements. At the same time, it posesses features normally reserved for heavy and expensive machines.  These features are: 

  • main landing gear suspension 
  • nose wheel brake with parking lock 
  • instrument console with engine monitors, rotor tach and flight instruments 
  • pre-rotator 
  • horizontal stabilizer 
  • conventional control stick 
  • fail-safe rotor shaft mount
The initial engine used was a 440 Kawasaki with 37hp. All flight testing was done with that engine. 

I am in the process of installing a 72hp McCulloch engine for real flying. 

From the March 1999 newsletter: 

Richard Sohn has enjoyed building and flying rotorcraft since he held a job in the German helicopter industry in the 1950s.  Richard built his first autogyro in 1956 and flew it until he crashed the autogyro in 1958.  Following the crash, Richard flew gliders until 1978 when he began high altitude hang gliding in the Alps.  Richard moved to the United States in 1979 and his glider flying was put on hold. 

In 1987, Richard made his first trip to Oshkosh and subsequently decided to build another autogyro.   Richard soon began work on his Unicorn autogyro and has been working on it ever since.  The design goal of the Unicorn project was to develop a legal ultralight with features normally found only on heavier aircraft. Landing gear suspension, brakes, and a prerotator were just three of such features. The Unicorn is currently flying with a Kawasaki 440 snowmobile engine, but Richard is working on a single cylinder wankel (rotary) engine for the future. 

The landing gear suspension is simply a fiber glass strut that flexes as a load is applied to it.  The braking system of the Unicorn consists of caliper brakes on the front wheel.  These brakes are used for taxi only. 

 
 
 
The prerotator is an original design of Richard's.  He crafted a drive wheel that presses against the engine flywheel when activated by a cable on the control stick.  This drive wheel engages the rotor drive gear which Richard prerotates to 200 rpm.  The rotor rpm guage is another original design fashioned from General Motors ignition parts. 
 
 
 
In many ways, the Unicorn has been a test bed for Richard's other project, an XTC Amphibian that he bought a few years ago.  Richard has used the Unicorn autogyro to test and develop his ducted fan propulsion system which he hopes someday to mount on the XTC with the engine from a 1987 Mazda RX-7 Turbo.  The ducted fan system began with a hub from a high-speed industrial fan and Richard fabricated the shroud and fan blades from fiberglass.  The fan is driven through a belt reduction drive at 3700 rpm. 
 
 
 
Richard says that the fan blades are the most difficult items to fabricate.  He has slowly perfected his technique and now fills his injection mold with randomly oriented glass fibers and longitudnal carbon fiber rods before injecting the epoxy resin.  This process produces very strong but lightweight fan blades that seem to hold up well under the high stress of the ducted fan system.  Richard is, however, considering a switch from epoxy resin to vinyl ester. 
 
 
Richard Sohn truly personifies the "experimental" in Experimental Aircraft.  If any of this experimentation sounds interesting, stop by and visit Richard.  His airstrip is located about 8 miles north of Mossy Head and he monitors Crestview Unicom.  When you get into the pattern, give him a call on 122.9.  He says he'd love to have visitors anytime. 
 
 
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Last updated on August 15, 1999