Takeoff Run Research Articles

Improved Algorithm for Takeoff Monitoring

The scope of takeoff monitoring is to provide a measure of aircraft performance during the takeoff run and to identify whether this lies within the predetermined limits of scheduled performance or otherwise. Used in conjunction with a good display, such a system, provided it is adequately reliable, will provide critical situational awareness to the crew and will thus contribute towards improving safety during takeoff. Cranfield University has developed a takeoff performance monitor based on an algorithm that determines estimates of relevant parameters from the history of the particular takeoff run, rather than relying on scheduled estimates. This, however, resulted in a delay between the start of the run and the generation of the first estimate of performance. This paper describes the improvements in performance achieved by the introduction of a modification that uses measured thrust-to-weight ratio to significantly shorten the delay and improve prediction accuracy, particularly at the start of the run.

Design of a Morphing Airfoil Using Aerodynamic Shape Optimization

An in-house high-fidelity aerodynamic shape optimization computer program based on a computational fluid dynamics solver with the Spalart-Allmaras turbulence model and a sequential-quadratic-programming algorithm is used to obtain a set of optimal airfoils at the different flight conditions of a light unmanned air vehicle. For this study, the airfoil requirements at stall, takeoff run, climb gradient, rate of climb, cruise, and loiter conditions are obtained. Then, the aerodynamic shape optimization program is used to obtain the airfoil that has the optimal aerodynamic characteristics at each one of these flight conditions. Once the optimal airfoils at each flight condition are obtained, the results are analyzed to gain a better understanding of the most efficient initial airfoil configuration and the possible mechanisms that could be used to morph the single element airfoil. The results show that a very thin airfoil could be used as the initial configuration. Furthermore, a morphing mechanism that controls the camber and leading-edge thickness of the airfoil will almost suffice to obtain the optimal airfoil at most operating conditions. Lastly, the use of the optimal airfoils at the different flight conditions significantly reduces the installed power requirements, thus enabling a greater flexibility in the mission profile of the unmanned air vehicle.

Composites lift off in primary aerostructures

The take-off run for aerospace composites has been prolonged, but now that designers feel more comfortable with these materials, they are incorporating them into primary aerostructures – as well as into the design codes, qualification loops and other features of the necessarily safety-first aviation culture. As a result, we may be witnessing lift-off and could, given further impetus, see composites climb high. George Marsh reports.

Evaluation of Perceived Motion During a Simulated Takeoff Run

In de Nationale Simulator Faciliteit (NSF) werd bij een ervaren verkeersvlieger bepaald welke simulator bewegingen veriest zijn voor een realistische sensatie van lineaire versnelling tijdens een gesimuleerde take-off.

Situation-Adaptive Autonomy for Time-Critical Takeoff Decisions

This paper presents a probability model for analyzing risks in rejected takeofis (RTO) of aircraft. The human pilot usually bears full responsibility for deciding whether to continue the climbout (Go) or to abort the takeoff (No Go) upon an engine failure in the takeoff run. Making a correct Go/No Go decision is not an easy task under time-criticality, especially with uncertain information, inappropriate RTOs which end with overrun accidents are reported annually. Discussions on whether to automate the Go/No Go decision-making system, to avoid unnecessary RTOs made by the human pilot, have taken place. This paper proves that Go/No Go decision-making should neither be fully automated nor be left always to the pilot, and that authority for Go/No Go decision-making must be traded between the human pilot and the automated system in a situation-adaptive manner. This paper also proves that the human-interface of conventional warning systems is not effective for reducing RTO accidents, and that a new design of human-interface systems is necessary.

Measurement of aeroplane takeoff speed and cabin pressure

Two experiments have been performed aboard a commercial airliner. The first experiment used a pendulum to determine the kinematics of the take-off run. The second experiment used a water-filled manometer to investigate changes in cabin pressure.

The wing of Archaeopteryx as a primary thrust generator

Since the late 1800s, the debate on the origin of flight in birds has centred around two antagonistic theories: the arboreal (take-off from trees) and cursorial (take-off from running) models1,2,3,4,5,6. Despite broad acceptance of the idea that birds evolved from bipedal and predominantly terrestrial maniraptoriform dinosaurs1,7, the cursorial model of flight origins has been less successful than the arboreal model. Three issues have contributed to this lack of success: the gap between the estimated maximum running speed of Archaeopteryx (2 metres per second) and its estimated minimum flying speed (6 metres per second)8; the high energy demands of evolving flight against gravity2,3; and the problem of explaining the origin of the ‘flight’ stroke in an earthbound organism3,4. Here we analyse the take-off run of Archaeopteryx through lift-off from an aerodynamic perspective, and emphasize the importance of combining functional and aerodynamic considerations with those of phylogeny1,9,10. Our calculations provide a solution to the ‘velocity gap’ problem and shed light on how a running Archaeopteryx (or its cursorial maniraptoriform ancestors) could have achieved the velocity necessary to become airborne by flapping feathered wings.

Speed Dependence, Takeoff and Stiction of a New Class of Gas Bearing Sliders

While searching for a less-speed-sensitive programmable air bearing slider, the author noted that the primary reason for the sluggish takeoff and large dependence of fly height on speed is the very common 10 mrad taper. This taper is found on many sliders in the railed, taper/flat class. A single, plane wedge bearing operating at a large bearing number and a pitch angle considerably below that which gives maximum lift does not suffer from such speed sensitivity. The “inlet throttled” condition of the bearing inlet fixes the mass flux into the bearing gap. Because a single pad of this type has poor pitch stability, the author placed two of these pads in a tandem configuration, and abandoned rails. The result defines a new air bearing class, called Tango, which has front and rear pads, each having inlet throttled leading edges. Some members of this class offer takeoff velocities equalling and even improving more-complex designs using subambient pressure. In addition, numerical and hardware experiments have verified the considerably reduced sensitivity of fly height to speed, a reduced sensitivity to crown distortion, and improved stiction. Disk designers benefit by not having to accept a longer takeoff run when the fly height decreases.

Impact of Ramp Launch Technology on a Navy Support Aircraft

L IGHT aircraft carrier designs are being considered in order to increase the number of air-capable ships and disperse air power more widely at sea. The deletion of catapult launch devices is a major contributor to reducing the weight, complexity, and cost of these ships, but this requires aircraft with short takeoff run capability. The ramp launch technique developed by the British and used by the Sea Harrier, which is a very high thrust-to-weight ratio design, is shown to be applicable to reducing the deck run of conventional Navy aircraft. A short takeoff using a free deck run and a ramp is achieved by lifting off at a speed less than stall speed and accelerating to a 1-g flight speed during a ramp induced semiballistic flight trajectory. This paper shows the impact of the ramp launch technique on low thrust-to-weight ratio aircraft and describes a design study to modify the Navy S-3A ASW aircraft to operate from a light aircraft carrier with an 800-ft deck run and a 4-deg circular arc launch ramp.

Visibility Reduction due to Jet-Exhaust Carbon Particles

Abstract Pyrolysis of hydrocarbon fuels leads to emission of free carbon in the exhaust of aircraft turbojet engines, visible as a faint dark trail. Carbon formation rises markedly when water injection is employed to augment thrust by 20–30 per cent in takeoffs under heavy loads or at high temperatures, the enhanced pyrolysis resulting from the lower combustion efficiency on such “wet takeoffs.” During the takeoff run, while the aircraft is still moving at low speeds but with maximum thrust, dense dark smoke fills the exhaust wake, reducing visual ranges to as little as a few hundred feet. To crow-check recent measurements indicating carbon particulate emissions of the order of 15 lb per ton of fuel consumed in wet takeoff, Mie extinction coefficients have been computed for carbon particles of the size known to form as a sequel to pyrolytic freeing of carbon. These are used to make theoretical estimates of the maximum visual range to be expected if the carbon loading measurements were correct. A discrepan...

The Rôle of Jet Lift

In 1909 Monsieur Louis Blériot forged a link between our two countries, one might say an aeronautical link. He did so in an aeroplane which by today's standards took only a short take-off run and a short landing.Today there are signs of new links being forged between the two countries and among them is co-operation in the development of vertical take-off and landing aircraft. There can, therefore, be no more suitable subject for a lecture in commemoration of Louis Blériot than one on “The Role of Jet Lift.”

A Method for the Photographic Recording of Take-off and Landing Performanc

This method has been designed to give all necessary performance data, concerned with the take-off and landing of aircraft, in a cheap and efficient manner. The complete path of the machine from the start of the take-off run to beyond the screen is recorded on a single photograph and from it the reduction of the data is done readily and simply. In the case of a take-off the data obtainable is as follows :(a)Take-off run.(b)Nature and length of the transition.(c)Height at any screen.(d)Distance, velocity and acceleration at any point from the start.(e)Angle of climb.(f)Rate of climb.(g)Any irregularities in the flight path.Similar data can be obtained in the case of a landing. Any information may be extracted independently and the photographic negative filed for future reference.The camera used is simple and inexpensive, both in construction and subsequent use. Four persons at present form the total ground staff and with an improved camera now under construction one of these is eliminated.The accuracy obtainable with the present apparatus is sufficient to fix the position of the aircraft to within ± 2 feet. Once the initial work has been carried out on any aerodrome, future use of this method has been found to be simple, quick and sufficiently accurate for all normal requirements.

The Field of the Large Commercial Airship

T recent demonstration flights of the Hindenburg have revived American discussion of the merits of commercial airships. Since the discussion seems now to have moved from the popular literature into technical publications, it appears desirable to bring before aeronautical engineers the technical fundamentals underlying the situation. This article is offered in an attempt to clarify the respective merits of various types of aircraft and to show that they may efficiently be fitted into a world-wide transportation system. Speed is, of course, the accepted advantage of air travel over surface transportation. In order to assure patronage overland, aircraft must exceed by a sufficient margin the speed of the automobile and the train and must make up for the time lost between an airport and the heart of a city. The actual speed based on elapsed time between points of departure and destination depends greatly on the time lost in intermediate stops. A compromise must be attained between the delay of intermediate landings and the economic advantages of reasonably frequent stops for refueling and crew relief. The longer the individual non-stop distance the more the fuel load encroaches upon the payload. In order to attain the maximum ton-miles of payload carried by any aircraft a certain ratio of payload to fuel load is most advantageous. For most overland and coastal routes it is possible to select airplanes that can operate over the required non-stop distances of say 1000 miles or less under conditions approaching these best ratios and hence with a desirable economy. For transoceanic flights, however, the situation is different. The transatlantic distance to Europe nonstop is of the order of 4000 miles. With intermediate stops such as Bermuda and the Azores, open stretches of ocean to be crossed are of the order of 2000 miles. Across the Pacific to the Orient the necessary non-stop distance is even greater. To take off with the fuel necessary to cover such distances, airplanes must sacrifice payload until the ratio of payload to fuel load is unfavorable. Therefore, across oceans these airplanes must operate much less economically than over land. Flying boats, not being limited for take-off by the size of existing airports, can be made to carry an additional payload obtained at the penalty of take-off run. With very high wing loading and high power loading in lbs. per hp. such a flying boat requires a great body of protected water where it can take off with what amounts to a virtual overload. This could explain why the flying boat figures usually published seem to include a payload superior to that of land planes in transport service. Under the conditions of best lift/drag ratio, best propeller efficiency and best specific fuel economy, the airplane (as well as the airship) would yield a corresponding maximum conveyance output in ton-miles payload carried when the initial ratio of payload to fuel load is approximately governed by the transcendental equation