With the bugs worked out of the drive train and the belt and pulley configuration nailed down, it was time to take the project to the next phase. Work has already begun on a Mark II version of Goliath. The primary changes for the Mk II vehicle is a new lighter frame and ducts to enclose the rotors. Over the next couple weeks, there will be more project logs to document the new vehicle in more detail, but for now here's some of the progress that's been made.
After considering several options, it was decided to go forward with an aluminum truss frame. The primary reason was cost and ease of manufacture. A composite structure would be lighter, but the cost would be significantly higher. A preliminary design has been completed and the structural analysis has been completed. Below is an image of the structure layout and the predicted deflections under load. More details will be provided in a later project log.
The materials have been ordered and arrived this last week. Below is some of the tubing (3/4" and 1/2" diameter).
However before the structure can be built, a jig is needed to assemble the parts. Work has begun on the jig for the upper portion of the vehicle.
The other big change for the Mk II vehicle is the addition of ducts. The duct serves a couple of purposes, the foremost of which is safety. The duct will prevent the rotors from hitting people or objects and to potentially contain debris if the rotor itself fails. Secondly, the duct will improve the total thrust of the vehicle, if designed correctly.
Each duct will be built in two halves to make building and assembling the ducts easier. A prototype duct piece has already been built to test out the manufacturing process. Eventually this duct will be tested on the new vehicle.
The black material is the surface of the mold that stuck the duct because the directions for the mold release were misread.
Stay tuned for more updates in the near future.