We have recently developed and tested a formation control algorithm for fixed-wings in Paparazzi. The position of an arbitrary number of vehicles can be controlled in a circular path. In fact, we are not restricting ourselves to circles but to any closed orbit, such as ellipses, thanks to the guidance vector field that guides the planes.
The algorithm is under more tests, but it should be soon available for the general public. It is quite easy to employ, the user has to declare only the IDs of the planes, the communication topology (neighbors' relationships) and the desired inter-angles.
In the following video the planes exchange positions every second. Delays, out-of-date positions (GPS delays), packet losses, etc are expected to be (and actually they are) present. It is quite interesting to remark how robust the algorithm is. According to our calculations the impact of such nasty things are not very important (ofc up to a certain point) for the convergence of the algorithm.
The work will be submitted to the next IROS conference. Once the paper is ready, I will also post it here just in case somebody is curious about the details.