Toroidal Ballute Research Articles

Effect of shock interactions on the attitude stability of a toroidal ballute for reentry vehicles

An aerodynamic ballute system is an inflatable large aerodynamic decelerating device that can enhance the drag force drastically by a large frontal area. This enhanced drag force can reduce the ballistic coefficient of the reentry vehicle system, which can mitigate the reentry heating environment.

Direct Simulation Monte Carlo Simulations of Ballute Aerothermodynamics Under Hypersonic Rarefied Conditions

This paper presents computational results obtained with the direct simulation Monte Carlo method for towed ballute applications. A ballute is an inflatable drag device that can be used to create a large amount of drag at high altitudes. Consequently, ballutes provide a potential technology for achieving aerocapture when the primary spacecraft velocity reduction ( V) is achieved at much higher altitudes than with the conventional rigid aeroshell. Because the V is achieved at relatively high altitudes, rarefaction can be significant and is the motivation for the current study with the direct simulationMonte Carlo method. Computed surface and flowfield results are presented for a toroidal ballute, isolated tethers when exposed to freestream flow conditions, and the flow interactions resulting from a toroidal ballute when towed by a 6 m diameter Mars Pathfinder shaped (without tethers) spacecraft. All results presented are for Earth entry at velocities of 14 to 7 km=s (primary focus is at 8:55 km=s, same as some previous Titan aerocapture studies) and altitudes of 200 to 100 km. Variations of drag and heating coefficients as a function of rarefaction are presented. Adescription of theflow structure is provided and also an explanation of how it is affected by shock interactions produced solely by the ballute and those resulting from the two body combination of towed ballute and spacecraft is also given.

Experimental Expansion Tube Study of the Flow over a Toroidal Ballute

An experimental investigation of high-enthalpy flow over a toroidal ballute (balloon/parachute) was conducted in an expansion tube facility. The ballute, proposed for use in a number of future aerocapture missions, involves the deployment of a large toroidal-shaped inflatable parachute behind a space vehicle to generate drag on passing through a planetary atmosphere, thus, placing the spacecraft in orbit. A configuration consisting of a spherical spacecraft, followed by a toroid, was tested in a superorbital facility. Measurements at moderate-enthalpy conditions (15-20 MJ/kg) in nitrogen and carbon dioxide showed peak heat transfer rates of around 20 MW/m(2) on the toroid. At higher enthalpies (>50 MJ/kg) in nitrogen, carbon dioxide, and a hydrogen-neon mixture, heat transfer rates above 100 MW/m(2) were observed. Imaging using near-resonant holographic interferometry showed that the flows were steady except when the opening of the toroid was blocked.