Reply to post: I thought I recognised this as previously debunked junk

I thought I recognised this as previously debunked junk

I went to the website, pointed my browser at 'theorypaper9-4.pdf' and got and empty file. wget says 403 forbidden so the EmDrive fully lived up to my expectations. There is a 'principle of operation' page. The diagram has changed since last time.

Before, the magic chamber was a triangle, and the mathematics showed that the force on the roof was smaller than the sum of the forces on the other two sides. The mathematics conveniently used scaler addition, even though all three forces were in different directions. The correct mathematics would have summed the vertical components of the three forces and got the inconvenient result of 0. Despite the glaring defect in the mathematics, the project was still funded by the UK government.

This time, the picture is a trapezium, and the hand waving fuzzy argument talks about an EM wave with a 'large velocity difference at the reflector surfaces'. Electromagnetic waves all travel at the same velocity in vacuum. To get a velocity difference, you need two different materials, or a mixture of materials that smoothly changes composition with distance. As reading the theory is forbidden, I can only guess at the technique used to hide the defective mathematics. The way I would do it is to focus on the radiation pressure from reflection at the two ends and not mention the force on the (unshown) graded material in the middle.