Sean Tuttle

Drag measurements at Mach 5 using a stress wave force balance

The stress wave force balance, which has been used for measurements of drag on short models in hypersonic impulse facilities, is investigated here for its suitability for drag measurements on a longer, axisymmetric model. The sensitivity of the balance to loading distribution is investigated and results are reported for experiments on a 5° semi-angle cone, 425 mm in length and of 1.71 kg mass. Experimental drag measurements are shown to be in good agreement with theoretical levels. An investigation into the period over which the stress wave force balance can be used is addressed and, for the present model, the balance is shown to be suitable for measurements in flows of durations of one to several milliseconds with an estimated accuracy of ±10%.

Force Measurement in Hypervelocity Impulse Facilities

A new technique is described and demonstrated for measuring drag with 100 µs rise time on non-lifting models in free piston shock tunnels. Extensions of the technique to measurement of lift and moment on a body and thrust from a scramjet nozzle are discussed.

A drag measurement technique for free piston shock tunnels

A new technique is described for measuring drag with 100-microsecond rise time on a nonlifting model in a free piston shock tunnel. The technique involves interpretation of the stress waves propagating within the model and its support. A finite element representation and spectral methods are used to obtain a mean square optimal estimate of the time history of the aerodynamic loading. Thus, drag is measured instantaneously and the previous restriction caused by the mechanical time constant of balances is overcome. The effectiveness of the balance is demonstrated by measuring the drag on cones with 5 and 15 deg semi-vertex angles in nominally Mach 5.6 flow with stagnation enthalpies from 2.6 to 33 MJ/kg.

The new mission of 'rosetta' comet chaser and in-orbit first temperature results

The Rosetta spacecraft was re-targeted to a newly selected comet following a one-year launch delay. The thermal control of the spacecraft has to cope with a large Sun distance range - 0.88 to 5.35 AU - and increasing comet activity combined with operational conditions that span from full payload activity to power saving hibernation mode. The new mission stretches the range of solar flux even further than the original mission and some adaptations to the thermal hardware were required. This paper describes how the new demanding mission scenario influenced the thermal design of the spacecraft and its operations. Then, the thermal behaviour of the spacecraft as revealed by the first in-orbit results is evaluated and compared where possible with the response anticipated by the analyses and by the environmental thermal test programme results. Rosetta was injected into an Earth escape trajectory on March 2 th 2004 by an Ariane 5 dedicated launch.

Balances for the Measurement of Multiple Components of Force in Flows of a Millisecond Duration

Paper reports a new balance for the measurement of three components of force — lift, drag and pitching moment — in impulsively started flows which have a duration of about one millisecond. The basics of the design of the balance are presented and results of tests on a 15° semi-angle cone set at incidence in the T4 shock tunnel are compared with predictions. These results indicate that the prototype balance performs well for a 1.9 kg, 220 mm long model. Also presented are results from initial bench tests of another application of the deconvolution force balance to the measurement of thrust produced by a 2D scramjet nozzle.

Developing a stress wave thrust balance for a hypersonic shock tunnel

The development of a thrust balance for the measurement of the net thrust produced in a scramjet nozzle is described. The balance has been designed and tested in the T4 shock tunnel at the University of Queensland. Numerical simulations of the balance and measurements made in the shock tunnel demonstrate that the thrust is correctly recovered when the loading in the nozzle is symmetric, but unexpected pressure asymmetry in some cases prevented successful recovery of the thrust.

Lift, Drag and Thrust Measurement in a Hypersonic Impulse Facility

This paper reports the extension of the stress wave force balance to the measurement of forces on models which are non-axisymmetric or which have non-axisymmetric load distributions. Recent results are presented which demonstrate the performance of the stress wave force balance for drag measurement, for three-component force measurement and preliminary results for thrust measurement on a two-dimensional scramjet nozzle. In all cases, the balances respond within a few hundred microseconds.

Reaction Control Thruster Thermal Design for a Mission to Mercury

This paper describes two novel methods used to reduce the prefiring injector temperatures of thrusters on the sun-facing side of a spacecraft designed for a mission to Mercury. The Mercury Transfer...

EUCLID mission design

EUCLID, a medium-class mission candidate of ESAs Cosmic Vision 2015–2025 Program, currently in Definition Phase (Phase A/B1), shall map the geometry of the Dark Universe by investigating dark matter distributions, the distance-redshift relationship, and the evolution of cosmic structures. EUCLID consists of a 1.2 m telescope and two scientific instruments for ellipticity and redshift measurements in the visible and nearinfrared wavelength regime. We present a design concept of the EUCLID mission which is fully compliant with the mission requirements. Preliminary concepts of the spacecraft and of the payload including the scientific instruments are discussed.

Re-entry Trajectory Modelling for the Microgravity Experiment Recoverable Satellite

A sizing exercise has been performed on the heat shield geometry for a small ballistic reentry capsule based on the Microgravity Experiment Recoverable Satellite concept. Here the complete on-orbit configuration is deorbited and follows a ballistic re-entry profile. The vehicle and its internal payload are thermally protected by a PICA heat shield. This paper reports the development of a simple re-entry trajectory simulation using a Newtonian drag force approach which is used to examine the dependence of the re-entry trajectory, peak heating and the peak front-side and back-side heat shield temperatures on the re-entry angle and heat shield geometry. An axisymmetric finite difference model was used to calculate the resulting temperature distributions through heat shields of different thickness. This analysis approach was used to show that a heat shield geometry incorporating a 50°coning angle and a 3cm thick PICA TPS should adequately protect the payload during re-entry.