Revision details:-Added spreadsheet specific to and clarifying aspect ratio for Ring Wing performance (new attachment)-Added weight penalty to represent control surfaces of alternate configuration with mid wing---------------------------------------------------------------------------------------------------------1. The AirPod drone is a 1.7m diameter, tail sitting, annular wing modular VTOL cargo drone design inspired by childhood memories of flying circular wing paper planes, the Heinkel Lersche, and other fascinating VTOL aircraft like the Snecma C450. It is intended to be a modern take on these unusual designs but using the latest flight control technology and design techniques.
2. It has a minimum of 4 electric motors for propulsion in the tractor or pusher configuration, a fixed annular wing for fast efficient forward flight and structural robustness. A pusher optimized for forward flight is centrally mounted. AirPod will rely on highly responsive differential motor thrust for simplicity and control, however mid wings (X configuration) and control surfaces may be added to the trailing edges if needed. Take-off weight is expected to be in the region of 12-25 kg and additional motors around the circumference may be added for greater payload duties.
3. The aircraft starts sitting on the ground with its motors pointing straight up. It will ascend from its launch pad using these motors and gradually transition to fast forward flight by tilting over and transitioning onto the annular wing. Forward flight speed is expected to be around 80kph, but will be electronically governed below 194kph. Nearing its destination, AirPod will guide itself safely downward with 2 options: a brief period of controlled glide on a ballistic like trajectory slowed for final descent by reversing motor rotation, to finally land upside down. If cargo, thrust, weight and power do not permit this profile, the drone will transition to the upright near its destination for final descent for a regular quad–like landing descent.
4. AirPod is able to spend decent amounts of time in hover mode safely and efficiently where others may be susceptible to wind gusts, and will have a complete airframe parachute for adverse flight termination. Being a blown, ring wing design AirPod will have efficient lifting and fast forward performance.
5. The central modular cargo pod is interchangeable for different mission duties. Medical staff may operate the AirPod. Inside the removable pod, the charged flight batteries and cargo are fixed to a special motorized platform that automatically positions the load to achieve the correct CG balance. The operator loads and suspends the cargo pod on the yellow balance point and the internal IMU and lead screw system will move the payload to the correct position. There is a rear mounted sensor gimbal which can be re positioned depending on the mission. Cargo preparation, batteries and loading are done completely indoors in safety and comfort. The prepared pod is then taken to the aircraft and fitted, ready for takeoff. When the cargo pod is fitted, electrical connections are made via IPX rated waterproof connections ESC's are in the motor fairings) and the aircraft can be armed for flight. The cargo pod is intended to be fitted from below or alternatively from above. Thanks to these features, rotors will not spin until the pod is fitted, the operator(s) are clear and vehicle armed.
6. Transportation is easy, with no need for separate wing panels (left or right confusion) and the possibility to leave the weather resistant airframe on the launch pad until the payload and avionics are fitted. Flush stowing carry handles on the payload module and airframe are provided for transport. A single person may position the aircraft on its launch pad with the aid of the castoring wheel landing gear. The annular wing is intended to be dismantled into 8 main sections, possibly 3D printed for ease of maintenance and transport. Being symmetrical design, the wing panels are the same around the circumference which significantly reduces inventory and complexity. The panels stack and nest together. The main spar/ chassis assembly is of a bolted up frame design and can be broken down into hoops, semi circles+pods or further. Therefore the aircraft is extremely compact and portable. Th entire assembled aircraft is less than 2m in size, but can be broken down even smaller for transport. Rotor guarding has not been included for this embodiment, but additional hard points have been designed inboard to move motor locations so that propellers are completely enclosed within the annular wing.
7. Thank you for the challenge and for reviewing