This study presents a design and examines its effectiveness for a sub-orbital flight experiment named RadFlight proposed by European Space Agency to simulate a super-orbital entry flight. The super-orbital entry flights of unmanned space vehicles returning from Moon or Mars will undergo severe convective and radiative heating and ablation. The project RadFlight proposes to modify a submarine-launched missile named VOLNA, which normally produces a sub-orbital entry speed to a 700 kg-class payload, to produce an 11 to 12 km/s entry for a smaller entry vehicle. Observations will be made of the radiative and convective heating rates and extent of ablation in the entry vehicle. The heating environment to be simulated by RadFlight is that of Fire 2, Stardust, or Apollo missions.
This study is the first in this group effort to present a comprehensive design of the RadFlight experiment, and to assess the effectiveness of this flight design in simulating the physical phenomena of interest: conversion of radiative heat flux into convective heat flux by the absorption of radiation and their effects on the ablation of the heatshield in the boundary layer.
The laminar boundary layer flow field in the stagnation and downstream region of the re-entry vehicle is described by a set of partial differential equations, and solved numerically. Radiation is peak at the edge of boundary layer, and is totally absorbed in the boundary layer. The ablation rate, which is unsteady in this environment, is calculated kinetically by numerically implementing surface-kinetic phenomena. The heatshield of the present study is assumed to be a carbon-phenolic. Unlike an existing viscous shock layer method, the rate of ablation at the surface of heatshield, in the present study, is obtained as an output parameter.
The method is applied to examine the feasibility and to evaluate the effectiveness of the two proposed designs: 1) booster-integrated design and 2) booster-separable design. Accura...