5 ms·

Considering how much waste heat can be thrown off by high powered microwave stuff (as in the original resonating cavity waveguide horn setup of the emdrive, whi

Considering how much waste heat can be thrown off by high powered microwave stuff (as in the original resonating cavity waveguide horn setup of the emdrive, which people thought to be producing thrust), I am not surprised at all that the apparent thrust was thermal expansion and contractions. Klystrons and TWTAs are not exactly known for being low wattage pieces of equipment, in terms of their TDP (thermal dissipated power). Ask anyone that's ever worked on a 1000W+ uplink power amplifier for two way geostationary satellite stuff... It's a lot of heat to get rid of. So these guys are trying to duplicate results of like 1 millinewton per kilowatt, meaning you'll need a microwave source of at least 3-4kW, of course it's going to throw off a lot of heat. I do wonder if any of the scientists trying to duplicate this effect have thought to bring in some commercial industry manufacturers of big C, X, Ku band TWTAs and get their advice on building a test rig. Or to try modern small but high power GaaN SSPAa vs TWTAs... https://www.cpii.com/docs/datasheets/17/t22ci_mkt326.pdf https://www.cpii.com/docs/datasheets/17/t22ci_mkt326.pdf https://www.cpii.com/products.cfm/153 https://www.cpii.com/products.cfm/153 Even very low powered terrestrial microwave radios are a lot of waste heat compared to what they output in rf. The radio head on a ptp microwave dish setup that is a 35W load on -48vdc might be outputting around +18 into the waveguide, equivalent to around 200 milliwatts. The rest is all radiated into the atmosphere and what it's mounted on. This why you'll see ridges of heatsink fins on the body of a full outdoor modern 18 or 23GHz radio. This is considered to be totally normal (a 35W 1024qam dual linear polarity radio with a capacity close to gigabit Ethernet line rate is sure a big improvement over a full 42RU rack size Harris Megastar 64QAM radio consuming 1800W from 25 years ago)

Gravityloss 6y ago
Counterfactual: Assume it worked, let's say it's producing a millinewton per kilowatt. That would mean one could put it on a spinning arm with a generator in the center and make overunity power. If you ran it at 1 m/s, it would only produce 1 milliwatt (1 mN * 1 m/s). Underunity. If you ran it at a million metres per second, it would produce its own power, 1 kilowatt. And if you ran it at 2 million metres per second, it would produce twice the energy that it consumed. 2 million metres per second is 2000 km/s and less than 1% of light speed. Relativity can be ignored. Would it be possible to build such a system? In vacuum with UHMWPE wire, one could build a spinning system 2000 kilometers in diameter that would spin 3 times per second. The centripetal acceleration would be 200,000 gees. Wikipedia tells me this is in current ultracentrifuge acceleration range. https://en.wikipedia.org/wiki/Ultracentrifuge https://en.wikipedia.org/wiki/Ultracentrifuge

Gravityloss 6y ago

Counterfactual: Assume it worked, let's say it's producing a millinewton per kilowatt. That would mean one could put it on a spinning arm with a generator in the center and make overunity power. If you ran it at 1 m/s, it would only produce 1 milliwatt (1 mN * 1 m/s). Underunity. If you ran it at a million metres per second, it would produce its own power, 1 kilowatt. And if you ran it at 2 million metres per second, it would produce twice the energy that it consumed. 2 million metres per second is 2000 km/s and less than 1% of light speed. Relativity can be ignored. Would it be possible to build such a system? In vacuum with UHMWPE wire, one could build a spinning system 2000 kilometers in diameter that would spin 3 times per second. The centripetal acceleration would be 200,000 gees. Wikipedia tells me this is in current ultracentrifuge acceleration range. https://en.wikipedia.org/wiki/Ultracentrifuge https://en.wikipedia.org/wiki/Ultracentrifuge