# Design of a Human Muscle-Powered Flying Machine
## 2 Classification of HPAs  
According to the classification proposed by The Royal Aeronautical Society (RAeS) [32], a HPA is considered to be an aircraft heavier-than-air that is sustained in flight by the flapping of surfaces and the reaction of air.  
Based on the type of propulsion construction, several types of HPA can be identified:  
1. Propeller-Driven HPAs with Fixed Wings: These are some of the most commonly used design solutions. Typical for propeller-driven HPAs, a fixed wing serves solely as a lifting element, and a slow-turning propeller is powered by the pilot's muscle force.
2. HPAs with Movable Wings (Ornithopter): These perform movements of the lifting surfaces that mimic the flapping of bird wings (ornithopters) or insect wings (entomopters). Wing flappers also include backpack HPAs, where a pair of wings is directly attached to the torso and arms of the pilot.
3. HPAs with a Rotating Lift Rotor (Rotorcraft): These include designs inspired by helicopters (a lift rotor directly powered by the pilot) or gyroplanes (lift generated by an unpowered rotor as a result of the forward motion of the rotorcraft relative to the air, driven by a propeller powered by the pilot).  
This paper focuses only on the construction and design of the first type of HPA, which is propeller-driven with fixed wings. However, it is worth mentioning the progress of the remaining types in a few sentences.  
[PERSON] et al. (2020) explore preliminary calculations for human-powered ornithopter (HPO) performance, focusing on a model termed the \"simple ornithopter\". The paper introduces how this model interacts with the environment and derives a formula that relates the ornithopter's theoretical propulsion to its kinematic and physical parameters during horizontal flight. This theoretical framework is crucial for guiding the calculation and design stages of HPOs, offering a structured approach to optimize their performance based on fundamental aerodynamic principles and operational constraints. The movement of the ornithopter's center of gravity due to aerodynamic forces is essential for propulsion development. The algorithm for constructing an HPO is divided into two stages: first, selecting airframe parameters to achieve horizontal flight with a power expenditure of 250-300 W, followed by calculating the propulsion to ensure it exceeds the drag force.  
[PERSON] reported (2020) some basic data for development in a 1985-1990 human-powered helicopter (HPH). His team did not succeed, but several valuable lessons were learned. Designing a human-powered helicopter requires an aerodynamic and structural theory that surpasses conventional helicopter design limits (2020). To achieve flight, an HPH must have extremely large and exceptionally lightweight rotary wings to lift both the pilot engine and the structure. [PERSON]'s study (2020) demonstrates that such a rotor system can be lightweight, maintain its geometry to prevent coning and twisting, avoid interplanar interference, generate sufficient lift, provide inherent aircraft stability, and that the drag penalty from external bracing wires is compensated by their benefits.  
All aspects of helicopter design--aerodynamics, structures, materials, controls, and propulsion--are integrated to create the simplest and most efficient helicopter possible. Similarly to the HPA, the HPH has its own competition called the Igor I. Sikorsky HPH Competition. AeroVelo, composed of students and graduates from the University of Toronto, began flight testing its Atlas quad-rotor human-powered helicopter (HPH) on 28 August 2012 (2020). On 13 June 2013, AeroVelo's Atlas HPH stayed airborne for 64.11 s, reached an altitude of 3.3 m, and drifted less than 9.8 m. After reviewing the flight data, AHS International awarded AeroVelo the prize on July 11. Issues related to HPH have been discussed in greater detail in thesis (2020) and a recent paper (2020).