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The mission includes development of standardized payload subsystems and manuals that facilitate increasingly complex future payloads and the maximum transfer of corporate knowledge to future student participants. Additionally, the mission will provide opportunities for students to design, implement, and test innovative systems through hands-on experience and collaboration between disciplines, universities and practicing aerospace engineers and scientists.

Project DIONISYS: Mechanical Components

Nosecone Payload tube Payload frame Umbilical block Drag plate Radax joint Parachute recovery sys. Separation system

Payload Tube

 

A image of the payload tube un attachedRequirements:

14” outside diameter
Mate to nosecone on top end
Mate to separation system
Minimum bending moment of 100,000 in-lbs

Description:

The payload tube is to be 14" in diameter tube with a wall thickness of 1/8". It will have holes machined into it to allow for the following penetrations:

Sun sensor
4 - Pressure equalizing ports Umbilical block
GPS antenna cables
Transmitter antenna cables

Materials

The payload tube construction method will largely depend on what materials can be acquired at a reasonable cost. The options, in order of most to least preferable are:

Wound Carbon Fiber Tubing. This would provide the highest strength-to-weight ratio. A custom supplier will probably be necessary for this option (minimum orders around $2000).
Extruded Aluminum Tubing. This would be the preferred choice for an aluminum tube. 7075 aluminum has high tensile strength and excellent machining properties. Its main drawback is that it can’t be welded without subsequent heat-treating. Therefore, it must be a seamless extruded tube as opposed to a rolled and welded tube. 2024 aluminum also is an option. It has the same properties as 7075 with the exception of a slightly lower tensile strength.
Rolled Aluminum Tubing. Our margin of safety would be much lower than with an equivalent weight tube in 7075, but a payload tube of this type should be more than adequate for SRP-4. The main advantage is that 6061 can be welded. This allows for local fabrication at a reasonable cost (approximately $400).

Interfaces:

The payload tube will attach to the nose cone with a double row of screws (see nosecone section) and it will attach to the radex joint with a lap joint. Due to the structural weakness of the lap joint a high strength epoxy is recommended to hold this joint together. Several 2-part room-temperature cure epoxies have been located that have shear strengths around 200K inlbs at 200 degrees F and much higher strengths at lower temperatures. NASA requires a bending moment of 100K in-lbs at this interface. Since this is a new technique, it is proposed that the joint be reinforced with a double row of 20 button-head screws. The button-head screws are chosen rather than flat-head screws, because they provide superior shear resistance. Protrusions from the payload skin in this region are not a significant issue due to the behavior of the boundary flow layer.