As exploring space grows in popularity, understanding zero gravity conditions becomes more and more important. Zero gravity, also known as microgravity, provides challenges in matters where Earth’s gravity is taken for granted. Tests are performed to solve issues that occur due to the lack of gravity. We are engineering an air vehicle that will be dropped from a drone, provide zero gravity conditions to a package inside the vehicle , and fall safely to the ground. Alternately, drop towers are used to simulate zero gravity for packages to experience free fall. Because of the small number of drop towers around the world, an easier method to conduct these tests is desired. Our team is creating a missile shaped vehicle, helpful for limiting the force that the surrounding air would provide as the vehicle falls. This force is the main issue that limits zero gravity conditions, as it creates an undesired acceleration. Our solution is to include a track for the package to move on inside the vehicle. The outside of the vehicle will slow down when the force from air acts against it, but the package will remain in zero gravity because it is free to move on the track. To increase the duration of the event, compressed water is used to propel the air vehicle down. The position of the package on the track inside the vehicle will determine when the compressed water will be released. After the test is complete, a parachute is deployed for the vehicle to descend safely to the ground. Our air vehicle is reusable and easily operated. This is a huge step for space exploration as the process of preparing for space’s atmosphere is quickened.
View our project's history from the beginning.
project scope target summary Customer Needs concept generation target catalog concept selection project plan Functional DEcomposition
Our final design was created by separating the system into the four subsystems shown below. These subsytems were designed and tested prior to the full system assembly.
Deceleration System
External Body
Payload System
Propulsion System
To minimize aerodynamic drag, our team opted for a long and slender exterior. It's made of lightweight Brown Kraft Paper and reinforced with water resistant Glassine. To stabilize the air vehicle along the z-axis, three fins made of sanded plywood are attached to the tail using Epoxy. These are laser cut to a "clipped delta" shape which produces the most efficient experimental attitude control.
Alignment Jig in Use
Fin Alignment Jig
Sanded Plywood Fin
Brown Kraft Paper External Body
The payload is free to move along a frictionless track, interfaced by linear bearings. This allows the package to remain in microgravity while the exterior slows due to drag. The assembly includes the payload, an adjustable holder, and four polished aluminum rods.
Carriage With Holster Attached
Payload Track System
59.5 mm
Top View of Track System
Payload Holster
The propulsion system provides thrust to offset aerodynamic drag. The thrust will be modulated to position the payload in the center of the track. The payload is monitored by an IR distance sensor. The assembly includes a 2-liter compressed water tank, a solenoid valve, and three symmetric nozzles connected by polyurethane tubing.
The deceleration system contains two parachutes: an initial one (termed “drogue” parachute) and a main parachute. These will be deployed when a servo motor releases the deadbolt for the lid. The drogue chute will be deployed by the piston and spring forcing it out. The parachutes will deploy after the four second microgravity event.
Parachute Storage Lid
Full Deceleration System
Parachute Storage
Controls & Dynamic Systems Engineer
Josh is a Mechanical Engineering major with an emphasis on dynamic systems and controls. He recently accepted a position with Prime Controls as an automations specialist in Austin, Texas and is looking forward to starting his career.
Aerospace Engineer
Evan is a Mechincal Engineering student with an interest in aersopace. After graduation he plans to work at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Systems Engineer
Brooke is a Mechanical Engineering major graduating Spring 2022. After graduation she is planning on moving to Colorado to pursue a career in Sustainable Energy Engineering.
Safety & Recovery Engineer
John is a senior in mechanical engineering interested in robotics and control systems. He led the design and implementation of the deceleration system for this project. After graduation he hopes to pursue a career in robotics.
Florida State University
Advisor
Florida Space Grant Consortium
Sponsor
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Static Website Generators . The body must be in freefall, meaning gravity is the only force acting on it. Since drag force is unavoidable, a thrust force must be generated to counteract it.
Normal falling object FBD:
FBD to achieve microgravity:
To counteract drag force, we will have thrust emitted from 3 nozzles, symmetrical about the nose cone. The nozzles will direct the thrust at a 10 degree offset angle, or tangentially from the nose.
While the goal is for the track system to be frictionless, that's much too difficult to achieve under our circumstances. This FBD displays the small amount of damping force at each connection point between the holster and the track. It will be small enough to be considered negligible though.
Exterior Testing: An online simulation, Open Rocket, was used to find the optimal design for the external body. Various combinations of sizes and shapes were tested to find the smallest resultant drag force.
