Hoh Aeronautics, Inc. has been working in the area of helicopter and fixed wing handling qualities and flight control systems for over 15 years.  Most of our helicopter experience has been in support of the U.S. Army.  This has included flight control system upgrades for army helicopters and the development of the flying qualities specification used for military helicopters around the world, Aeronautical Design Standard ADS-33E.  The RAH-66 Comanche fly-by-wire flight control system is being designed to meet this specification

Much of our work for the U.S. Army has consisted of research into limited authority flight control systems that can be used to economically upgrade existing helicopters to include an Attitude Command Attitude Hold stability augmentation system.  Research that we have conducted on NASA simulators and the Canadian NRC Variable Stability Bell 205 helicopter has shown that this type of augmentation is essential to reduce pilot workload in conditions of degraded visibility and where pilot division of attention in required.

We have also done a significant amount of work on displays and controls for fixed-wing aircraft.  For example, our company designed the symbology and control laws for the BAE Systems Head-Up display used for Cat III landings by Boeing 737-800 aircraft flown by major US and foreign airlines. 

The HeliSAS is a direct outgrowth of the research that we have conducted for the U.S Army.  It provides attitude command-attitude-hold augmentation using many of the concepts that resulted from that work. 

The development of the HeliSAS was motivated by the fact that light civil helicopters have handling qualities that require considerable piloting skill.  Such handling qualities would not be tolerated in military aircraft, most of which have stability augmentation.  The objective of the HeliSAS is to provide improved handling qualities for light helicopters at an affordable cost and minimal weight penalty.  

There is data to show that such improved handling qualities will have a positive impact on safety.  This is especially true for low-visibility and nighttime operations where the accident record is poor.  A primary objective of the HeliSAS is to improve the safety of operation of light civil helicopters.

Our military experience has resulted in a philosophy that only the highest quality components be used to provide an extremely reliable system.  However, by employing patented design techniques we have been able to develop the HeliSAS at a cost that is affordable for most R44 owners.  The weight of the system is approximately 11 lbs not including the attitude gyro.  The standard R44 panel mounted attitude gyro is replaced with our custom HeliSAS attitude gyro so there is no weight penalty.

The HeliSAS roll servo and flight control computer is located under the pilot's seat.  These components take up very little space leaving most of the area available for baggage.  The pitch servo is located under the radio stack.  The HeliSAS is designed to work with any R44 that is equipped with hydraulic controls.