Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

use of an auto-throttle, to control speed through engine thrust. For manual control, the technique is to control the airspeed through
pitch attitude and to maintain the glide slope by adjusting engine thrust. (4) The pronounced longitudinal non-minimum phase
behaviour due to the movement of large trailing edge lift producing surfaces for pitch maneuver control. With only wing trailing
edge mounted elevons for pitch control, their small moment arm requires a large control deflection to generate the required pitch
acceleration. The ,up’ elevon results in negative lift from the control surface and an initial loss in aircraft height until the aircraft
incidence is modified and total lift increased. This non-minimum phase behaviour, characterized by a positive zero in the response
transfer function, results in an undershoot in flight path response. Resulting in a hesitation in height response which may result
in a heavy landing if a correction is made late into the approach. (5) Significant delta wing generated ground effect resulting in
some cushioning of the landing, hence reduced sink rates. However, the negative pitching moments degrade the rate of nose rotation
on take-off and may prove disconcerning to the pilot when the aircraft leaves its effect. (6) The pilot’s location far ahead of
the undercarriage resulting in difficulty in judging mainwheel position during landing at high approach attitudes. (7) The capability
to generate relatively rapid rates of roll due to the inherently low roll inertia combined with the large and effective elevon control
surfaces. However, the low value of the roll damping derivative, L(sub p), leads to a large roll mode time constant since
-tau(sub p) approx. = I(sub x)/L(sub p), the roll control power of the elevons is also large resulting in a tendency to over-control
in roll. In addition, the rolling moment due to sideslip being a function of sweepback angle and incidence tends to oppose the
demanded roll maneuver if sideslip is allowed to build hence slowing the initial response. (8) A dutch roll mode characterized
by a near pure rolling oscillation due to the large value of L(sub nu) combined with a low roll inertia. In addition, it has a relatively
high frequency and hence short period, requiring the mode to be adequately damped to ensure acceptable handling characteristics.
(9) A large yaw/roll inertia ratio resulting in a tendency for the unaugmented aircraft to roll about the longitudinal body axis and
not the velocity vector, hence degrading heading response.
Derived from text
Aerodynamic Balance; Angle of Attack; Deflection; Degradation; Drag Reduction; Dynamic Response; Minimum Drag; Undercarriages
20000066590 Department of the Navy, Washington, DC USA
Neural Network System for Estimation of Helicopter Gross Weight and Center of Gravity Location
McCool, Kelly, Inventor; Haas, David, Inventor; Nov. 16, 1999; 5p; In English; Supersedes US-Patent-Appl-SN-09042045
Patent Info.: Filed 13 Mar. 1998; US-Patent-Appl-SN-09,042,045; US-Patent-5,987,397
Report No.(s): AD-D019711; No Copyright; Avail: US Patent and Trademark Office, Microfiche
The invention is directed to a helicopter health and usage monitoring system utilizing a neural network for estimating gross
weight and center of gravity location from measured flight condition parameter inputs; and includes means for measuring a plurality
of variable flight condition parameters during flight of he helicopter; memory means for successively receiving and storing
parameter input signals as well as estimates of gross weight and center of gravity location; and processing means responsive to
the signals received from the measurement means for generating the gross weight and center of gravity location estimates.
DTIC
Center of Gravity; Helicopters; Neural Nets; Weight (Mass); Weight Measurement
20
07
AIRCRAFT PROPULSION AND POWER
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20000061968 NASA Langley Research Center, Hampton, VA USA
Developing Conceptual Hypersonic Airbreathing Engines Using Design of Experiments Methods
Ferlemann, Shelly M., NASA Langley Research Center, USA; Robinson, Jeffrey S., NASA Langley Research Center, USA; Martin,
John G., NASA Langley Research Center, USA; Leonard, Charles P., NASA Langley Research Center, USA; Taylor, Lawrence
W., NASA Langley Research Center, USA; Kamhawi, Hilmi, TechnoSoft, Inc., USA; [2000]; 12p; In English; 21st;
Aerodynamic Measurement Technology and Ground Testing, 19-22 Jun. 2000, Denver, CO, USA; Sponsored by American Inst.
of Aeronautics and Astronautics, USA; Original contains color illustrations
Report No.(s): AIAA Paper 2000-2694; Copyright Waived; Avail: CASI; A03, Hardcopy; A01, Microfiche
Designing a hypersonic vehicle is a complicated process due to the multi-disciplinary synergy that is required. The greatest
challenge involves propulsion-airframe integration. In the past, a two-dimensional flowpath was generated based on the engine