T-Wing Aircraft Homepage



Welcome to the T-Wing vehicle home page. The T-Wing is a tail-sitter technology demonstrator UAV that is being jointly developed by the University of Sydney and an Australian company, Sonacom Pty Ltd. The T-Wing vehicle concept grew out of vehicle optimization studies conducted at the University during 1995-1999 by Dr Hugh Stone, for his PhD dissertation. Although in some respects similar to the Boeing Heliwing vehicle of the early 1990's it is fundamentally different in a number of respects. Some of the differences are:


      The use of control surfaces submerged in the slipstream of the vehicle's twin propellers to provide control during vertical flight (similar to the tail-sitter vehicles of the 1950's) as opposed to the use of standard helicopter cyclic control;

      The use of a canard to balance the aft wing and allow greater freedom in CG positioning; and

      A different fin and landing gear arrangement.


The T-Wing has a wing-span of ~2.1m and a MTOW of ~30 Kg. It is powered by twin 78cc 3W 2-stroke engines that turn 23 inch diameter propellers. The vehicle is controlled by an onboard PC-104 computer stack that drives all the servos and accepts inputs from the GPS and IMU sensors. The vehicle communicates with the ground via Radio Modem Serial Data link. So far the T-Wing has been flown in hover mode both manually (very briefly!) and under automatic control using Command Augmentation System (CAS) controllers. For hover mode, these map pilot stick inputs to velocity commands:


      elevator and rudder stick inputs become translational velocity commands;

      aileron stick input is treated as a (vertical attitude) roll-rate command; and

      throttle stick input maps to a vertical velocity command.


Tethered hover testing has commenced on the second airframe and on Monday 6th August 2002, the T-Wing flew with autonomous guidance in all axes except the vertical. Vertical position was controlled via a vertical velocity controller commanded by a remote pilot. Pilot input for vertical position control is necessitated by vertical height limitations of the tether system and the imprecision of DGPS altitude measurements. Once tether testing is complete, all pilot input will be removed. Once this is done, all axes will be connected to an onboard guidance loop which generates appropriate velocity commands for the controllers to navigate between a set of waypoints.


Tethered Hover testing resumed on 1st March 2005, with a total of 4 tethered flights exploring different vertical flight control modes and testing the integration of a new more accurate GPS receiver, pressure sensor and upgraded flight and ground-station software. Besides the standard vertical velocity mode tested previously, the vehicle was also tested with vertical angle-based controllers as well as rate-based controllers.

As of November 2005 we have installed a new avionics system which gives ~ 20 times increase in accuracy for the vehicle position, velocity and angle states. This has allowed us to conduct fully autonomous vertical flight testing with the tether test-rig. We have also been able to successfully fly the vehicle in 10-15 knot winds in both autonomous and vertical velocity guidance modes.


From May 2006 we replaced the 3W-78CC engines with Desert Aircraft 100CC engines to counter weight growth with heavier avionics and deterioration (with age) in the 78CC engine performance.


Between 1st and 30th August/2006 we have performed three transition flights, each involving at least one set of transitions between vertical and horizontal flight.


Videos of these flight tests are given on the Video page here.




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Last revised: Thursday, October 4th 2006

This page has been visited times since 19th Sept 2002.