Single-Winged Autorotating Aerodynamic Brake for Martian Atmospheric Entry
This research program investigates the feasibility of a single winged autorotating aircraft for delivering sensor payloads to the surface of Mars. The work consists of vehicle sizing, stability analysis, and computer simulation of the atmospheric entry. The possibility of flight testing scaled models in the earth's atmosphere will also be investigated. The work is being conducted by Ilan Kroo and Stephen Morris of the Stanford Department of Aeronautics and Astronautics and Larry Lemke of NASA Ames Research Center.
In a proposed Mars exploration mission, various sensor packages will be deployed from orbit onto the planet's surface. Deployment schemes under consideration include parachutes and surface penetrators. Another delivery mechanism is autorotation, such as is used by the winged seeds of Maple trees. A single winged autorotating device has the advantage of minimal complexity (no moving parts to fail during deployment) and compact storage. Such a system also offers an unobscured view of the sky during descent which may be important for the sensor payload. Currently, the dynamics of single winged autorotating devices is poorly understood. Few papers have been written on the subject and the mechanism for transition from free-fall to autorotation has not been studied in detail.
Computer simulations written at Stanford University by Stephen Morris have successfully modelled the transition from free-fall to autorotation in the earth's atmosphere and provide a useful starting point for designing an autorotating entry vehicle for Mars.
OBJECTIVES AND ANTICIPATED RESULTS
The principal objectives of the work are:
- Determine the appropriate vehicle size for acceptable descent speed in the Martian atmosphere
- Determine the mass distribution and planform shape that results in rapid transition to stable autorotation
- Investigate the possibility of a dynamically-scaled model that could be tested in Earth's atmosphere
A simplified aerodynamic analysis of steady-state autorotation based on local blade airfoil properties and simple momentum models is used to size the vehicle.
Transition to autorotation and stability is being studied using a six degree-of-freedom nonlinear simulation coupled with the derived aerodynamics model. Blade shape parameters are adjusted to meet the required descent rates with a stable vehicle.
The vehicles pertinent dimensionless parameters (tip Mach number, Reynolds number, dimensionless inertia, etc.) will be studied to see if a useful test may be conducted in the Earth's atmosphere.
firstname.lastname@example.org (Steve Morris)