landing, the HUD is very useful because of its accurate and rapid flight path indication and prediction. 11) See Fig.5.
Fig.5 HUD in Flight Test of Aska
Two NASA Ames Research pilots came to JAPAN to evaluate Aska They made five flight evaluations during lwo weeks. Because of their experience with the NASA QSRA powered lift aircraft, they were able to help significantly with the Aska flight test program 12)
This paper describes the principles of the display concepts, the flight experiments and the findings obtamed from these experiments.
DESCRIPTION OF HUD
DISPLAY CONCEPTS- Development of the HUD for Aska was guided by the three design requirements which are shown as follows.
1. The HUD should provide precise and flexible information to the pilot. The symbols for basic aircraft situation information such as attitude, air speed, angle of attack, trim condition and flight path information, etc. should be simple and Unconfusing.
2. The HUD should provide pseudo approach and landing information for the evaluation of handling qualities and performance of the aircraft at high altitude before being committed to a landing on a real runway.
3. The HUD should have the capability to make precise approach and landing in alt weather conditions by a displaying perspective runway and precise flight-path indications. The pilot should be able to use the same flight techniques for Visual Meteorological Conditions (VMC) and for Instrument Meteorological Conditions (IMC).
Fig.6 HUD Configurafion in Man-Machine System
HUD CONFIGURATION - The airborne HUD configuration, without the radar position update (which will be discussed later), consist of a Computed Signal Generator(CSG), Pilot Control Panel(PCP), and Pilot Display Unit(PDU) as seen in Fig. 6. Information from the Inertial Reference Unit(IRU) and from the Digital Air Data Computer(DA DC), through the SCAS, along with mode selection from the PCP are used by the CSG to generate the symbology for presentation on the combiner grass of the PDU. The pilot can see the outside view and the HUD symbology at the same time through the combiner glass. The goal of the HUD is to make a totally integrated flight instrument system with which the pilot can fully control the aircraft. The usefulness of the HUD is described in ref.13) to 16).
HUD DISPLAY FORMATS - HUD has six basic display formats which are the Basic Mode, Normal Mode, Velocity Vector Mode, and three Pseudo Approach and Landing Modes. The Basic Mode uses a real angle information for attitude indication. The Normal Mode is added more data to the Basic Mode for normal up and away maneuvering. The Velocity Vector Mode is added Flight path symbol and Flight path acceleration to the Normal Mode for precision flight path control. The Pseudo Approach and Landing Modes consist of the A Mode, B Mode and C Mode which all use the position information to generate a perspective runway
