Prandtl wing aircraft of the bloodlesshound project: Second version 2.25metre wing span.
The Prandtl wing is a tailless aircraft. This aircraft is a research vehicle intended to investigate the bell shaped lift distribution as suggested by Ludwig Prandtl in his 1933 paper on the efficiency of wings with a specific design mass and no span limitation.
The research was inspired by the NASA paper "On Wings of the Minimum Induced Drag: Spanload Implications for Aircraft and Birds," NASA/TP – 2016-219072. (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf)
The goals of the project is somewhat different from the NASA paper which focussed on proving the existence of proverse yaw with the Prandtl lift distribution. The goals are:
- Investigate whether or not a tailless aircraft designed to have a Prandtl lift distribution will have satisfactory unaugmented (no control system except for the pilot and direct gearing of the control surfaces) handling qualities.
- Determine the performance characteristics of such an aircraft. In particular is important to show very favourable L/D characteristics (L/D >= 53 for full scale aircraft) and laminar flow on the wing surfaces, even with reflexed profiles that are common on tailless designs.
A staged approach will be followed with the research. Firstly a small model will be built to establish manufacturing techniques. This step has been completed. Secondly a larger 2.25m span model will be manufactured with better performance characteristics. This is the current step. Lastly larger prototypes have to be designed and built in order to investigate the full scale properties of this type of aircraft. A full scale aircraft should have a 12 to 15m wing span. It is imperative that a full scale aircraft be manufactured since subscale tailless aircraft nearly always have satisfactory handling qualities. Full scale tailless aircraft have to be built in order to investigate the vulnerabilities of tailless aircraft to gusty conditions.
This aircraft will be designed and built using free and open source software as far as possible. Furthermore this design is to have version control using git. This is in order to investigate git's suitability as product lifecycle management software. The design will also follow a open hardware philosophy, similar to the open sourced software used to create it.
It is hoped that this project will encourage other builders to manufacture similar designs and publish their designs, software and data in a similar manner, so as to advance the state of the art of tailless aircraft in particular and engineering in general.