Stalling speeds and determination of manoeuver speed for Rogallo-winged microlight airplanes

Rogallo-winged airplanes can display a non-square law of stall speed versus loading. This Note shows, from experimental data, the form of this relationship and how this has been used during the certification of such airplanes, through operating data and modification of either maneuver speed or the normal acceleration limit

BCAR section S issue 2 - What is possible and a review of existing designs

British Civil Airworthiness Requirements Section S “Small Light Aeroplanes” is a standard based upon the European light aircraft standard JAR-VLA. It is an unusual standard in that it is a UK administered standard that is still in routine use and development, not having been superseded by a Joint Airworthiness Requirement (JAR). Section S applies to the artificially defined class of “Microlight Aircraft” (some of which are also referred to as “SLAs”)

Less weight more fun

Microlight Aviation is still in its infancy, yet in the 20 years since enthusiasts around the world started fitting lawnmower engines to hang-gliders or small makeshift wings progress has been remarkable. Since then, microlight flying has become a mainstream activity in General Aviation; in the United Kingdom alone Microlights are now 21% of civil registrations, outnumbering either gliders or homebuilt light aircraft. The rapid expansion in microlight or ultralight aircraft worldwide has unfortunately not been matched by the development or commonality of regulations. Even the name is not common; the UK, New Zealand and Ireland refer to “Microlights”, France refers to “ULMs” (Ultra Leger Motorise), whilst many other countries have preferred the term “Ultralight”, including the USA and Australia

Pushing the envelope

This article is a description of the manoeuvre envelope in microlight aeroplanes, and how it is determined

A timed method for the estimation of aeroplane take-off and landing distances

This paper describes a method by which, without the use of external personnel or equipment, take-off and landing distances of an aeroplane may be estimated. An error analysis for the method, allowing determination of outcome accuracy, is also shown. The method is validated through use of flight test results from two certification programmes: one on a light aeroplane, and one on a microlight aeroplane

Regression approaches for Approximate Bayesian Computation

This book chapter introduces regression approaches and regression adjustment for Approximate Bayesian Computation (ABC). Regression adjustment adjusts parameter values after rejection sampling in order to account for the imperfect match between simulations and observations. Imperfect match between simulations and observations can be more pronounced when there are many summary statistics, a phenomenon coined as the curse of dimensionality. Because of this imperfect match, credibility intervals obtained with regression approaches can be inflated compared to true credibility intervals. The chapter presents the main concepts underlying regression adjustment. A theorem that compares theoretical properties of posterior distributions obtained with and without regression adjustment is presented. Last, a practical application of regression adjustment in population genetics shows that regression adjustment shrinks posterior distributions compared to rejection approaches, which is a solution to avoid inflated credibility intervals.Comment: Book chapter, published in Handbook of Approximate Bayesian Computation 201

Protecting the flight test programme

Considerable effort is put into the safety risk assessment of any flight test programme - and rightly so, since failures to apply best practice in this area may cause significant expense, and in extremis loss of life. However, it must also be remembered that the flight test programme itself is an essential component in the development of the aircraft or system, and that even if safety is never compromised, the failure of a test programme to deliver the required results on time and budget can cause failure of the entire aircraft programme. This paper considers the areas in which planning and conduct of a flight test programme should be protected. In particular it considers the conduct of flight test personnel in ways which go beyond only safety training, the important of documenting all flight test planning and conduct and the continuous justification of flight test conclusions, planning project manning to ensure that the loss (for whatever reason) of key personnel or equipment does not cause complete failure of the flight test programme, how to recover from significant programme disruptions, and most importantly whilst protecting or recovering the flight test programme – how to ensure that safety is not compromised in the process

Flight test: Supporting the investigation of factors affecting loss of control of light aircraft

A quarter of all fatal General Aviation accidents in the UK during the period 1980 to 2006 involved Loss of Control (LoC) in Visual Meteorological Conditions (VMC). LoC has consistently appeared in accident statistics over this period, but at apparently different rates for different aircraft types. This raises two important questions - why do these LoC events happen and why is there a difference between aircraft types?. One case in point is that of the Cessna 150 /152 and over the 27-year period analysed, the Cessna 150 falls approximately on the average for fatal accidents in the UK GA fleet, whereas the Cessna 152 exhibits a lower accident rate. Brunel Flight Safety Laboratory, in conjunction with the UK General Aviation Safety Council, undertook to try and understand why this is so. The key design differences in relation to performance and handling qualities were researched using available published material and informal interviews with type-experienced students, pilots and flying instructors. A flight test programme was conducted using examples of both aircraft types to gather additional research data, to assess and compare the apparent performance and handling qualities (both qualitatively and quantitatively). Flight tests were performed at three different CG conditions relevant to the key design differences, concentrating upon apparent longitudinal (static and dynamic) stability and control characteristics, stall and low-speed handling characteristics, and cockpit ergonomics / pilot workload. In all tests, normal (unmodified) flying club aircraft were used, in most cases with a 2-man (TP+FTE) crew. Data was recorded manually on test cards and automatically using a low-cost, commercially available, portable FDR. Proven theory was used to estimate static margins and pilot stick forces and gradients in the region of the stall, the pre-cursor to an LoC event.General Aviation Safety Council (GASCo

The 'tumble' departure mode in weightshift-controlled

The cost of private or recreational flying is high for most conventional aircraft types. During the last 25 years, however, an alternative has become available in the form of the microlight aircraft. It has a relatively low cost of ownership and has opened up flying to a greater audience. However, there have been a number of accidents, usually fatal, to this class of aircraft, which could not be explained through any conventional understanding. The reason for these accidents, which involve a departure from controlled flight followed by aircraft structural failure (generally including mechanical failure of the basebar, wingtips and leading edge), has become known as the `tumble’, owing to the basic motion of the aircraft. This paper analyses the tumble mode, from its initiation through to the steady rotation condition. History has shown that the tumble mode has always resulted in the destruction of an aircraft. In consequence, it is the authors’ opinion that consideration of the tumble during the approval of new designs should concentrate upon avoidance, since there is no identi®able recovery mechanism from the established mode without the use of an external safety device. A programme of research into this phenomenon was initiated in 1997. The peculiar nature of the tumble motion has required the aerodynamic modelling to address the effects of a high pitch rate, which has led to the introduction of unsteady aerodynamic effects. This paper sets out to describe and explain the mode, leading to a model that might reasonably be developed to produce relatively tumble resistant aircraft. Finally, the methods of possible entry are explained; it is intended that this information may be used in pilot training to ensure the avoidance ofthe tumble instability