Takeoff Stall and High Speed Taxi, A Case Study

Applying Flight Research to Flight Test –

Takeoff Stall and High Speed Taxi, a Case Study

Anthony P Brown
National Research Council Canada
Ottawa, Ontario, K1A 0R6

One element of Flight Research studies aircraft performance and flying qualities, and thus addresses the influence of applied aerodynamics thereupon. Flight Research is undertaken from a fundamentally different precept to flight test. However, the practices of flight research follow the principles of flight test – flight research techniques tend to be based upon flight test experience, and the development and usage of flight research techniques follows the ‘build-up’ principle. Perhaps because the objectives of aerodynamics flight research are highly defined, the reverse procedure might not be often used, in practice – namely, folding the benefits of flight research back into flight test practice. It is contended, herein, that there is benefit in doing so. Flight research into dynamic stall upon takeoff, and the flight research techniques applied thereto are presented and discussed, as a Case Study, for doing so. Initially, examples of flight techniques applied to aerodynamics flight research at the NRC are given. Then, a study is presented into the sporadic occurrences of incidents and accidents over many decades, involving abrupt wing stalling of jet transport aeroplanes near the ground, sometimes preceded by relatively high pitch rates, whether pilot-induced or otherwise, sometimes involving wing roughness, and often leading to wing drop and complete loss of control. Incidents and accidents of this nature have periodically occurred over the full history of jet transport operations, involving many different Type Designs, ranging from the first jet transport to contemporary Type Designs. In many, but not all, of the instances studied, the dynamic stalling involved coupled roll or roll/yaw characteristics, including wing heaviness, abrupt wing drop, yaw, and wing rock. On occasions, the wing drop and wing rock have appeared coupled with pilot-induced aileron deflection. The viscous flow dynamics, as influenced by boundary layer coupling to rigid-body motion in free-air, is outlined. The continuing trend of such events and the often abrupt nature of the departure from controlled flight highlight the desirability of undertaking a programme of aerodynamic research into the influences of the ground plane, pitch-rate, surface roughness state, aileron deflection and environmental conditions upon wing stalling. 

Designing, Building and Flight Testing a Home Build Aircraft to Set a Wrold Distance Recod

Abstract

Designing, Building, and Flight Testing a Homebuilt Aircraft to Set a World Distance Record

Arnold E. Ebneter, Lt Col, USAF, RetFAA Designated Pilot Examiner

Woodinville, WA
425.486.8821
This email address is being protected from spambots. You need JavaScript enabled to view it.
Member, SETP and EAA

Eileen A. Bjorkman

Technical Advisor, Air Force Flight Test Center
Edwards AFB, CA
661.275.2074
This email address is being protected from spambots. You need JavaScript enabled to view it.
or This email address is being protected from spambots. You need JavaScript enabled to view it.
Member, SFTE and EAA

The E-1 is a single-place, single-engine, reciprocating aircraft designed and built by one of the authors, Arnold Ebneter, with the intent to set a world distance record in the less than 500kg weight class of aircraft.  Forty five years after the design was originally conceived, first flight of the E-1 took place on 12 July 2005 at Harvey Field in Snohomish, Washington.  The record setting flight was flown 25-26 July 2010; Mr. Ebneter departed Payne Field in Everett, Washington, at 1415 local and touched down 2011 miles later in Fredericksburg, Virginia after 18 hours and 16 minutes of flight with 2.5 gallons of fuel remaining.  The record has been certified by both the NAA (US record) and FAI (world record) and Mr. Ebneter’s accomplishment was recently recognized by the NAA as one of the “Most Memorable Aviation Records of 2010.”  This paper will first briefly describe some of the tradeoff decisions and manufacturing challenges encountered during the aircraft design and construction process.  The paper then describes the flight test techniques used to determine maximum range performance of the aircraft, from using hand-held stop watches and fuel gauges, to using more sophisticated instrumentation, including GPS and advanced engine monitoring and avionics systems available in modern homebuilt aircraft.  This section also includes a brief discussion some of the modifications made to the aircraft to reduce drag and increase fuel efficiency.  The final section describes the flight planning and actual record-breaking flight.  A briefing version of this paper was presented to the Northwest SETP Chapter in September 2010, and the E-1 has been featured in articles in the EAA publication Sport Aviation (August 2006 and January 2011 editions) and the UK magazine Today’s Pilot (February 2007).

A400 Development Flight Testing - A Wide Spectrum of Challenges

ABSTRACT

  AIRBUS A400M DEVELOPMENT FLIGHT TEST PROGRESS

Presented by Ed Strongman and Charlie Mai, Airbus

 The A400M military transport is a modern technology, fly-by-wire aircraft that integrates Airbus design elements to meet the military requirements of the European Air Forces.  First flight was on 11 Dec 2009 and following the initial civil certification and follow-on military testing, entry into service is planned for early 2013.  Initial flight testing has concentrated on developing and showing compliance with core Part 25 requirements.  This includes engine/propeller/airframe compatibility testing, initial stall testing, Vmu determination, Vmcg and Vmcg determination, ice shape testing and anti-icing system development, and performance determination, both AEO and OEI.  At the same time work has started on the military functions to be able to check the aircraft’s capability to achieve its military tasks.  These tests have included rough runway and gravel runway simulations, initial paratroop drops, and the first air refuelling contacts.  The presentation will cover the highlights of the flight test programme to date.

 

Abstract

AIRBUS A400M ICE SHAPES CAMPAIGN

 

Presented by Fernando Alonso and KH Mai, Airbus

 

 

The A400M Fly-by-wire Flight Control system includes an Angle of Attack protection system to insure Stall protection.

The settings of the protection system must be such that it allows the expected high levels of manoeuvrability whilst ensuring the protection for a clean wing as well as for a wing fitted with simulated ice shapes in non-protected leading edge parts.

To safe engine and aircraft performance the A400M wing Anti-Ice system is designed to prevent only ice accretion on defined areas of the leading edge. These areas were estimated by analysis and wind tunnel tests. The first configuration could not be proven as optimum after initial ice shape high AOA trials.

The presentation will cover a brief description of the A400M F/CTL AOA protection and the WAI system with its original configuration of de-iced leading edge areas.

It will cover the highlights and safety aspects of the Artificial Ice Shape flight test campaign and test results, including all consequences for reconfiguration of the leading edge WAI system to recover aircraft performance while equally maintaining and not increasing the engine bleed performance requirement.

 

Developement of JSOW C-1 F/A-18E/F

Developmental Test of JSOW C-1 on the F/A-18E/F Super Hornet brings the first Net Enabled Weapon capability closer to the Fleet

 LT Scott “Beav” Johnson, USN (M)
Joint Standoff Weapon (JSOW) Project Officer

VX-31, NAWS China Lake, CA

 

CDR Andrew “Face” McFarland, USN (M)
NAVAIR 4.1.1.6 JSOW Class Desk Officer

PMA-201 Precision Strike Weapons Program Office
NAS Patuxent River, MD

ABSTRACT

The term “Net Enabled Weapon” (NEW) refers to the notion that ultimately – and in the very near future – the shooter, weapon controller, and targeting source for smart weapons need not be and in many scenarios will no longer be the same aircraft.  The C-1 variant of the Joint Standoff Weapon (JSOW C-1) is the first NEW that will be fielded within the U.S. Department of Defense (IOC 2013).  Small Diameter Bomb II will be the second such weapon to field in the years that follow.  The baseline JSOW C is a GPS guided glide weapon with an Imaging Infrared (IIR) seeker that enables aimpoint refinement against pre-planned stationary land targets, and has demonstrated a CEP of less than 5 feet.  The JSOW C-1 variant adds a Link-16 datalink to the weapon, which in concert with new Moving Maritime Target (MMT) algorithms, will allow for a standoff Anti-Surface Warfare (ASuW) capability against ships at sea, with a required SEP of less than 20 feet.

The complicated task of integrating JSOW C-1 on the F/A-18E/F Super Hornet presents the test team with many challenges.  This paper focuses on three major topics:

  1. Issues associated with the development and execution of the flight test matrix
  2. Safety concerns affiliated with dynamic captive carry flight profiles
  3. Human Factors challenges related to weapon integration and operation

 

Test planning and execution for this project have proven to be extremely challenging.  With increased capability and complexity come an exponentially increasing number of test points.  Cloud cover, time of day, sea state, target type, weapon profile, instrumented ship target and Sea Test Range availability, test aircraft availability, software configuration, and aircrew proficiency are the major variables at play in the testing of this complex system.  Although the test team developed a matrix which tests all of these variables with margin, schedule and budget targets remained seemingly unattainable at times.  Lessons learned will be presented on this front.

In order to fully test the JSOW C-1 MMT end-to-end capability, an inordinate number of livefires would be required.  Given budget and schedule constraints, the most cost-effective way for most of the functionality to be tested is via simulation and “captive carriage” testing.  The captive carry profile representative of actual weapon flight is extremely dynamic and involves negative g maneuvers in close proximity to the ground.  These maneuvers presented the test aircrew with many hazards, some which were identified and mitigated through the safety planning process, and others that were discovered during test.

 NEW capability is a quantum leap in warfighting solutions, but the flexibility comes at a cost.  This cost is Aircrew Workload.  Although there was a Simulation Design Advisory Group early on in the program, it was unfortunately focused more on the functionality of NEW and less on human factors evaluation.  This paper presents how human factors deficiencies have been identified throughout various stages of the test program, and the importance of identifying deficiencies and solutions as early as possible.

 Although this paper presents lessons learned unique to the testing of Net Enabled Weapons, they remain applicable to any complex test effort that includes extensive use of a human-vehicle interface.

Testing and development of a new warning system for low G-suit pressure in JAS 39 GRIPE

Testing and development of a new warning system for low G-suit pressure in JAS 39 GRIPEN

By Mr Johan Sjöstrand (M) and Mr Christer Berglund Saab Aeronautics S-58188 Linköping Sweden

To say that pilots were gods, the question about anti-G suit pressure or not, would be negligent...
but we are not and therefore dependent of anti-G pressure supplying the anti-G suit.
Modern aircraft expose pilots for accelerations of 1 to 9 G in just seconds. In the Gripen aircraft
the pilot is exposed to high loads for long periods of time. Therefore the Anti-G protection is very
important. Low pressure or loss of pressure in the anti-G suit at high G-loads is very severe and
could lead to a fatal accident. As in all fighters with analogue equipments such as hoses, valves
and sensors, loss of G-suit pressure could be a reality and this has in fact occurred in the Gripen
aircraft a few times. Fortunately, no severe incidents occurred on these occasions. 

Due to these incidents with loss of anti-G suit pressure and since there is no warning for low
pressure, it was decided to implement a new warning system that warns the pilot in case of low
anti-G suit pressure.
This paper describes the design, development and testing of the warning system as follows:
Dynamic Flight Simulator with pressure drops introduced in the anti-G suit during high G-loads.
Flight simulator tests to develop and verify the software before the flight testing.
Flight tests in test aircraft and production aircraft.
Parameters that had to be considered in the warning algorithm to avoid nuisance warnings.
Description of  pressure drops in the anti-G suit during high G-loads and a G-loc from the pilot’s
perspective
.