A method for predicting the rate and effect of approach to the stall of a microlight aeroplane

The stall and immediately post-stall behaviour of a microlight aeroplane are shown to be a function of the deceleration rate prior to the stall; therefore, it is necessary to use a representative deceleration rate when determining the acceptability of stall and post-stall handling qualities. This research has found means by which the range of deceleration rates likely to be seen in a particular type can be estimated, so that flight test programmes can ensure these rates are included, and thus aircraft are confirmed to have acceptable stalling characteristics. Recommendations are made towards the use of this research for all aircraft type, and of further work which might usefully be carried out

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unusual standard in that it is a UK administered standard that is still in routine use and development, not having been superseded by a Joint Airworthiness Requirement (JAR).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”)

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

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

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

Safety for non-microlight pilots

Microlight aircraft are some of the safest, cheapest and most fun aircraft flying in the UK. The fatal accident rate, at around 1 per 30,000 flying hours is similar to that of General Aviation overall, and rather better than some parts of it in recent years. However, at the BMAA we see several perfectly serviceable aircraft per year written off by very experienced GA pilots, typically with several thousand hours. Why? - well because they are different, not more difficult or more dangerous, just different. The phrase “it’s only a microlight” has as much validity as “it’s only a jet fighter” all aircraft will treat you back as they are treated

Pushing the envelope

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

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

Loss of control testing of light aircraft and a cost effective approach to flight test

Copyright @ The Society of Flight Test EngineersLoss of control in Visual Meteorological Conditions (VMC) is the most common cause of fatal accidents involving light aircraft in the UK and probably worldwide. Understanding why LoC events occur and why there are apparent differences between aircraft types is currently under investigation by Brunel Flight Safety Laboratory (BFSL). Using a case study approach for selected light aircraft used in the training environment and based upon a 29 year study of UK fatal accidents, BFSL undertook a qualitative and quantitative review of fatal stall/spin accidents using a combination of statistical and qualitative analysis. Aircraft/model design differences and published material were reviewed with respect to performance and handling qualities for possible clues, and informal interviews were conducted with type-experienced students, pilots and flying instructors. A flight test programme was executed using multiple examples (for fleet-wide attributes) of aircraft models to enable assessment and comparison of flying qualities (both qualitatively and quantitatively). Working within the continuous budget constraints of academia, a creative and cost effective flight test programme was developed without compromising safety. The two-man team (TP & FTE) used standard (unmodified) flying club and syndicate aircraft in conjunction with non-invasive low cost flight test instrumentation. Tests included apparent longitudinal (static and dynamic) stability and control characteristics, stall and low-speed handling characteristics and cockpit ergonomics / pilot workload. During this programme, adaptations were also made to the classic Cooper-Harper “point tracking” method towards a “boundary avoidance” method. The paper describes tools and techniques used, research findings, the team's lessons learned and proposed future research. It also discusses the possible application of research results in aircraft, pilot and environmental causal factors, enabling a better understanding of LoC incidents and future avoidance within the light aircraft community.Financial support from the Thomas Gerald Gray Charitable Trust Research Scholarship Scheme was used in this study

Towards the tumble resistant microlight

The tumble mode is a pitching departure from controlled flight which leads to a pitch autorotation that is generally unrecoverable – resulting in vertical ground impact, usually preceded by in-flight breakup (the mechanism for which, surprisingly, can sometimes prevent loss of life). This was identified in work led by the British Microlight Aircraft Association beginning in 1997 as a response to a number of fatal accidents in Rogallo winged microlight aeroplanes, although the tumble is also known to occur to hang-gliders. This paper explains how this class of aeroplane is controlled, and how it has been found that they can enter the tumble mode. The mechanism by which the tumble can be entered is described. This has led to work showing how flight testing can be used to establish and demonstrate resistance to tumble entry – particularly important with increasing number of very high performance flexwings. These flight tests will be explained, together with the significance of the results. Recent accident investigation work has also shown a new mechanism of tumble entry, through partial failure of the A-frame structure and the pitch-trimmer mechanism. Also described is a possible relevance to well known historical accidents to flying wing aeroplanes – specifically the YB-49 and dH-108, and discovered data on the characteristics of the BKB-1 flying wing glider; are also described