Question

project question:

'Design and build a thrust measurement system for model aircraft engines '

1- Questions

i) sketch

ii) ideas

iii) plan

iv) introduction, background, theory , abstract etc...

Answer 1

(iv)

Abstract

The Good estimation of aerodynamic coefficients is of fundamental importance in the design and development process of an aircraft. Generally, these parameters are ob- tained using analytical, numerical and experimental methods, which are sometimes either inaccurate or very expensive. The use of subscale aircraft is becoming in- creasingly common in the study and evaluation of new aircraft concepts. Flight testing results in an efficient solution for obtaining parameters that can define drag characteristics.

here is the solution for achieving the drag aerodynamic model from the design and manufacturing of a micro engine thrust measuring sys- tem integrated on subscale aircraft. Strain gauge technology permits to identify the stresses that the engine forces cause to the aircraft internal structure by analysing the strain of several strategic zones of the engine mounting created for this purpose.

Intorduction

Knowledge of aerodynamic behavior under real operating conditions is important for optimizing the performance of an aircraft. The use of measurement methods during flight is increasing due to the importance of obtaining accurate aerodynamic models for the design and construction of aircraft.Subscale models can represent a good option for estimating such parameters in full-size aircraft, either because of the possibility of studying them in wind tunnels or due to the lower complexity in the dynamic measurement procedures.

Several methodologies are currently implemented in order to estimate in-flight drag behaviour on subscale aircraft.This project presents a drag estimation from the in-flight study of the thrust model and the measurement of certain flight parameters of a subscale aircraft.

Theory

  In order to obtain the values of the dynamic thrust of the model, a measuring system has been implemented in the mount of the engine, between the mounting clamp and the internal structure of the aircraft. The horizontal force implemented by the exhaust gases of the jet turbine is directly transferred to the structure of the aircraft. Measuring this mechanical force, the thrust can be determined.

Here the measurement is based on the elastic deformation of certain structures using strain gauges. This is the operating principle of the load cells.Therefore, the objective is to perform an coorect structure or piece capable to join the model and the engine and, at the same time, equipped with this type of gauges to determine the strains. The collected data will enable the computation of the forces applied to the structure and consequently the thrust of the engine.

(i)

Several design are given below

  (a) Binocular configurations for tensile forces

(b) Binocular configurations for tensile forces

(c) Axial ring configuration

   (d) Axial ring configuration

   (e) Bending beam configuration

  (f) Other configurations

(g) Alternative Solutions

(iii)

The first decision that must be taken is the type of anchor that the engine will have, which allows to measure the forces that it exerts on the aircraft. In this case, there are many possible options to consider, from modifying some parts of the existing anchor to replacing the original mounting system with another that fulfils both functions. The degree of change, the difficulty of the new assembly and the added weight must be taken into account when assessing the possible options. The structural design must always work in the elastic region, enduring fatigue and ensuring deformation in measurable strain values. Some of the relevent aspects are;

• Weight of the support.
• Space required
• Difficulty of implementation and assembly
• Interdependence of strains due to horizontal and vertical forces

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