Btw, and this IS RELEVANT TO HOMEBUILDING! If you get to the bottom of that Project Rho page, you get to the EM drive and how NASA screwed the pooch on the most important discovery in science history. Allegedly. I'm putting all the weasel words right here. Allegedly!!! Dr. Pournelle should get full credit for pointing out the fundamental flaw in NASA's testing. They used a torsion scale. Understandably , they used the biggest hammer they had. The most sensitive force measuring tool in the lab. One capable of measuring the gravitational pull of a bowling ball! Freaking impressive! NASA had this big hammer so they think everything is a nail. Unfortunately It's the wrong tool. What you need to test if there is thrust from a reactionless drive, is a vacuum chamber, and a pendulum suspension. A vacuum chamber, so that a cooling fan of ionic air flow, or... Don't push on your test. This also will reveal a concealed compressed gas "leak" providing thrust etc. A pendulum suspension. Two points, so the gizmo won't spin etc. And thrust axis is more or less perpendicular to local gravity. Use non magnetic materials in your suspension system. Say, kitchen twine. Or hemp rope. Use a non contact position measuring device, like a simple interferometer. Suspend your gizmo in the chamber. Let it settle. Turn it on. If it swings back & forth, you have a negative result. If it moves to one side AND STAYS THERE, displaced from center, and swings back to eventual rest when power is cut, you have a positive. You are not done! You now have to eliminate every suggested cheat, but you will have experimentally verified for the first time in history, the possibility of a real Drive. NASA didn't do that. To my knowledge, no one has. Every other experiment in the West had been to disprove NASA's test. I don't know what the Chinese government did, but they announced they were going to go into production. Odds are near 100% that is a lie and propaganda to mess with the rest of the planet. I don't need to violate site policy on political opinions about the People's Republic, because I might do the same.& if anyone in charge there has a similar sense of humor it explains their announcement & subsequent silence on the subject. There's a science manager over there who might burst into spontaneous giggles thinking about frantic, expensive efforts in Moscow & Area 52 trying to beat him to an imaginary breakthrough. So how does this apply to US? When your expensive tool you love doesn't give the results you need, back off a moment and consider, "Am I seeing everything as a nail because I have this great hammer?" That $500 rivet gun can't do the job? How about your neighbor holding a foot long rod and you using a 16 oz. Ball peen hammer? ( irony!) That rented vibration tester can't get past a vibrating fairing to measure your prop? Silly putty and duct tape. Your engine coughs on climb out and every fuel pressure gauge reads perfectly? Get some friends to help you stick your tail in a ditch & tie off to a couple of trucks to do a full power fuel flow test. Etc. Once again full credit to Jerry Pournelle. RIP.