Winter 2015

This Winter 2015/2016 newsletter covers the work accomplished from late November through March of 2016.

Full-sized Ringspar

Work in the hangar is restricted in the winter due to cold weather, other than organizing all the parts and equipment transferred from Mathis Field in November of 2014. Setting up shelving and performing rust prevention have been the major activities this winter.

RANS Flying

The RANS S6 has been permanently moved from Air Acres in Woodstock, Georgia, to its own hangar at the Jackson County Airport near Jefferson, Georgia. Flying of the airplane in the winter hasn’t happened, with completion of the remaining 12 of the 40 hours of Phase One to be done in the Spring. The move was precipitated by one of the partners terminating his lease on the hangar and shop, and the buildings and land being put up for sale.

Model 2014

With the new FAA drone regulations, the model has been moved back to the house from the Jefferson Airport. Tests here will be done locally, away from airports.

Model 2016

With the new model basically mechanically completed, the work has shifted to implementing all the electronics and wiring required. Making a VTOL model is much more complicated than a conventional flying model. The new model will have 12 servos, six engines, and two separate flight control computers controlling movement in VTOL and conventional flight. The wiring requires 36 separate wires to run and connect up in order for the aircraft to have autopilot capability in conventional flight and autonomous hovering capability in VTOL flight.

Much work has been done evaluating and designing the 13” diameter VTOL rotor for the vertical takeoff capability. Right now the prototype aircraft has gained a lot of unnecessary but expected weight, and weighs around 15 pounds. To get this to VTOL will require an electrical motor spinning the rotor at about 12,000 rpm, and producing around 3 KW( 4 hp). Several prototype props and motors are currently undergoing spin and thrust testing to come up with the best combination.

Laser cutting

The first test runs of AutoCAD-generated parts produced by laser cutting have been completed and have been a great success. The first parts were the plywood engine mounts for the four wingtip ducted fans, which use the same small electric motors. The holes for the engine mounts were perfectly placed for drop-in attachment of the motors.

Work is in progress to generate multiple blade ducted fan turbines using the same procedures. Once completed, these will substitute for the standard design props used as fan blades in the five ducted fans in Model 2016.

Model 2016 in assembly

jyrodyneThe photo on the left shows the status of Model 2016 in late January, obviously in partial basic assembly, but with a lot of work to do to finish it up. All six of the electric motors have been commissioned. The 4” diameter ducted fan pods at the wingtips typically operate with a redline at about 12,000 rpm, but were then tested to failure. Prop failure occurred at approximately 26,000 rpm. The tractor propeller mounted above and to the rear of the central ducted fan has been tested to 14,600 rpm, with failure expected at about 19,000 rpm. Destructive maximum RPM testing for this 10” prop and the 13” prop used in the VTOL central ducted fan are not planned with the 13” proprotor limited to around 12,000 rpm.

The wingspan of the model is 8’-4”, with an all up weight of about 15 lbs. Weight reduction is in progress.

Fly By Wire Selected for aircraft controls

The work on Model 2016 has uncovered the need for multiple control capabilities which can enable autonomous operation for the full-sized Jefferson Jyrodyne. This includes conventional autopilot operations used routinely on our Piper TurboDakota, such as heading and altitude hold, vertical speed hold, and glide slope intercept, such as is found on almost all conventional IFR-rated aircraft.

In addition to this, required VTOL operations including:

  • hover over a point
  • hover and attitude adjustments due to wind gusts
  • general VTOL stability

These requirements suggest that electronics which can update 500 times a second will provide better capabilities than human operation with around 1 per second updates. This is not truly an autopilot operation though, since the pilot will not be fighting the controls as during autopilot excursions, but will be guiding the control direction while the VTOL autopilot enhances the stability and smoothness of the movements.

The electronics developed to perform the conventional fly-by-wire have been around for about 40 years, starting with the old F-16. The VTOL electronics however, come from the drone quadcopter technology, and can be directly scaled up from equipment used on radio-controlled aircraft models. Model 2016 uses the latest designs in quadcopter electronics and conventional gyro electronics.

Finally, the long distance control runs required from the cockpit to the rudders, elevator, ailerons, canard and flaps suggest that weight reduction and control response will be better with fly-by-wire capability rather than conventional controls.

A mechanical backup system in case of electrical failure will be included, but the details of this will remain confidential at this time.

Patent Updates

The original patents issued in 2005, after nearly 5 years working with patent examiners to get them. All the improvements developed over the past 10 years are being captured in new patent applications currently being worked on. It is expected that the first of these will be filed later this year.