This paper describes assumptions, goals, methods, results and conclusions related to fuel tank arrangement of a flying wing passenger airplane configuration. A short overview of various fuel tank systems in use today of different types of aircraft is treated as a starting point for designing a fuel tank system to be used on very large passenger airplanes. These systems may be used to move fuel around the aircraft to keep the centre of gravity within acceptable limits, to maintain pitch and lateral balance and stability. With increasing aircraft speed, the centre of lift moves aft, and for trimming the elevator or trimmer must be used thereby increasing aircraft drag. To avoid this, the centre of gravity can be shifted by pumping fuel from forward to aft tanks. The lesson learnt from this is applied to minimise trim drag by moving the fuel along the airplane. Such a task can be done within coming days if we know the minimum drag versus CG position and weight value. The main part of the paper is devoted to wing bending moment distribution. A number of arrangements of fuel in airplane tanks are investigated and a scenario of refuelling – minimising the root bending moments – is presented. These results were obtained under the assumption that aircraft is in long range flight (14 hours), CL is constant and equal to 0.279, Specific Fuel Consumption is also constant and that overall fuel consumption is equal to 20 tons per 1 hour. It was found that the average stress level in wing structure is lower if refuelling starts from fuel tanks located closer to longitudinal plane of symmetry. It can influence the rate of fatigue.

The main aim of this analysis is to consider a mutual interference between aircraft motion and surrounding flow field. Euler flow model for inviscid, compressible gas and aircraft flight dynamics model was used to analyse quick dynamic manoeuvres. For such manoeuvres, aerodynamic hysteresis has a great influence on aircraft dynamics, which cannot be simulated with the assumption of quasi-steady aerodynamics. On the other hand, the aircraft motion as a rigid body strongly influences the flow field around itself. To account for this mutual interference, the Euler flow equations were used to obtain aerodynamic forces and moments acting on a simplified aircraft configuration (main wing+ tailplane only) during pull-out manoeuvre, and the flight dynamics equations of motion were used to describe dynamics of an aircraft. Initial conditions for the flight dynamics equation of motion were settled up coming from the solution of the Euler flow model. As a test case, a weak pull-out manoeuvre was selected. During this manoeuvre, the highest value of angle of attack doesn't exceed 12 degrees - the value which can be obtained from the classical approach based on flight dynamics equations of motion with quasisteady aerodynamics. However, coupled Euler flight dynamic model has much wider applicability, and can be used for the analysis of manoeuvres at high angles of attack, including large scale separation at sharp edges, unsteadiness and flow asymmetries even for symmetrical undisturbed flowficld case. This method, if successfully verified to a number of important flight manoeuvres (such as spin, Cobra manoeuvre, roll at high angles of attack and other) can open a new, very promising field in the analysis of aircraft dynamics.

Dynamic stability analysis of the World Class Glider PW-5 has been presented. Glider was assumed to be a rigid body of three degrees of freedom - two linear displacements and one rotation - all in the plane of symmetry. Responses of the glider due to gust and deflection of elevator have been determined. The Laplace transform has been applied to convert the differential equations into algebraic ones. The transformed algebraic equations, after a number of manipulations have been solved for the output variables. Partial-fraction expansions have been performed to obtain the inverse Laplace transforms from the Laplace transform table. Although some restricting assumptions have been made (rigid body, small disturbances) the presented results are original and have not been presented before. The airworthiness regulations (JAR, FAR) do not require performing dynamic analysis in order the glider to be granted a Certificate of Airworthiness by the national aviation authority. To certificate the glider it is sufficient to prove static stability by means of in-flight tests. Flying qualities are qualitatively estimated basing on subjective opinions of the test pilots