What I find fascinating about this is that such a design COULD actually work, and I believe I could at least come close myself without much trouble. In fact I am not at all sure I couldn't do it with less effort than the Dutch folks expended on perpetrating this hoax with CG.
There are some things we know with regard to the components shown:
- They said the motors they show are capable of more than 2000 watts each, to total 4000 watts or so. Motors of similar size and weight are available that are capable of over twice that power.
- Batteries and speed controllers of similar size to what was shown are available and sufficient to power them--if not for more than a few minutes.
- I have used a similar motor in a hand held winch that was able to pull me straight up at a rate of ten feet per second.
- I have had an electric bicycle that was able to propel me at 30 mph on the flat with 1000 watts.
- A human athlete is capable of putting out about 200 watts of energy at best, and so the device they show would have approximately 20 times what a human is capable of--at least for a short time, depending on how many batteries are used.
Now think about that: 20 times the power of a human to make a hang glider's wings flap a bit while flying.
It seems to me that the device they show is similar in scale and weight to a hang glider, which as we know works quite well. So the simple question to ask here is whether the power of twenty humans concentrated in a simple compact mechanical device that makes a light weight wing flap would be enough to move a hang glider forward more than it would be able to without such assistance. I think it could, fairly easily.
There is another question posed here which I find interesting as well: would you get more out of moving a propeller or by flapping wings like what is shown in the video? Now, I am certain a propeller with five or ten horsepower (1 horsepower = 746 watts) would help move a hang glider forward. Not that fast of course, but it might well achieve what was shown in the clip, when you consider that running forward with a hang glider will get you off the ground for a bit by itself. And if a propeller can do it, I think a flapping wing with the same power would as well. There are weight and efficiency problems with the mechanics needed to make wings flap, and obviously a simple propeller on a motor or two would be far easier to make and lighter. But, well, flapping wings have been around for quite a while, haven't they? And they work quite well. Long, thin, slow moving airfoils are more efficient as a rule than small, fast moving ones. So it is at least conceivable that a flapping wing, done right, could be competitive given technologies we have now--like super light and strong tube structures one can make with carbon fiber and fabric. Bird bones are hollow, super light and strong after all...