Calculation tools
for ornithopter models

There is no common calculation method for flapping wings. In every source of information different methods are being described.

All Orni calculation tools given below are based on the calculation method specified in the handbook Wie Ornithopter fliegen. Particularly, the power and the twisting of the wing at stationary flight situations can determinated with it.

Furthermore, the calculation method permits an approximate quantitative specification of dynamics and aerodynamics of profiled flapping wings, at least. Primarily, the numerical comparison of various influencing variables of flapping wings.

Profiled flapping wings and quasi-stationary flow conditions are presumed. Therefore, calculations only lead to useful results for a fast forward flight with a relatively low flapping frequency (large birds, flying with lift).

The calculating tools are only executable with the respective software applications.

Orni 1

Simple calculation tool
to describe the wing twisting

The equations of the handbook are used in a small MS-EXCEL calculation tool:

download Orni 1 (with a short instruction in English rel. 3.2, XLS 0.1 MB)

This tool primarily allows the calculation of wing twisting at given wing data.

The additional calculation of data of the flying model is highly simplified. The detailed calculation of the force progression while a flapping cycle has been replaced by assuming a sinusoidal progression of the force. Thereby, the interfacing of stroke motion and twisting remains unconsidered. Only the reference line (as gliding flight) and the amplitude of the sine half-wave (in the center of each wing stroke) are calculated. With that, the area under the curve progression and the size of a force, respectively, is calculable.

Orni 2

Calculation method for ornithopter models

The basic calculation method of the handbook How ornithopters fly is reconstructed step by step. Many of the itemised equations are generated with accompanying text, diagrams and pictures.

The abidance of the operational range of the lift coefficient of the used airfoil is automatically warranted in the calculation tool. Also, the setting of balance of forces during flight happens in a simple way. Therefore, one can certainly achieve the flight data of the chosen model configuration.

For the construction of a flapping wing model the calculation method descibes various force and moment developments at the wing. Furthermore, the required power and - above all - the wing twisting along the span is being calculated.

The calculation tool was written (in German) with the software Mathcad.
Because of the volume of data and pages it requires a little familiarisation.

The here listed calculation tools are to understood as open source software. Therefore, everybody is enabled to take a insight look in the calculation method. Everyone has the permission to relay, vary and particularly to correct and improve this source code.