August 21st, 2014
If the EmDrive is real, the challenge of developing a low-cost launch system for getting things from Earth to orbit will be solved. And also – the ships going to orbit can be really big. In fact, a ship as big as the Gen1 Enterprise could be gradually moved upward into the thin upper atmosphere, and then electric propulsion engines like the VASIMR can slowly accelerate the ship until orbital velocity is reached. This reminds me of the airship-to-orbit concept promoted by John Powell. John’s idea is to float airship platforms far up in the atmosphere and then use electric propulsion engines to get ships launched from there up to orbital speed.
As I noted in a recent post, to an observer the EmDrive will appear to work as a kind of anti-gravity device. You can imagine a Gen1 Enterprise slowing ascending straight upward with no propellant being ejected. Once the big ship is 100km or so high the VASIMR-like engines can kick on and get the ship going parallel to the Earth’s surface.
It can work in reverse too. The Enterprise could slow down and then Earth’s gravity will begin to pull it downward. The EmDrives can be kicked on to enable a slow, controlled descent. The normal problem with todays’ high speed re-entries of dealing with the tremendous heat due to the ship’s hull hitting the air at high speeds is eliminated. Going to space and back will thus get a lot safer.
And if the Enterprise could be completely built on Earth and then moved to orbit – this would give a huge cost savings! It’s really expensive today in terms of $/kg to move any hardware into orbit and to do construction work in orbit. Being able to build the Enterprise on Earth would be incredibly efficient. Workers could simply drive to work every day. Materials for the ship could be brought in on trucks. It starts to remind you of this.
The EmDrive could be the key enabling technology to make the Gen1 Enterprise practical to build. Yep – perhaps we can Build the Enterprise by using breakthrough technologies to lower its overall cost.
August 16th, 2014
In my last post I said that NASA’s recent testing of EmDrive-like microwave cavity thrusters was not invalidated because they had different models of engines that both produced thrust. I should add that they did include a true dummy engine that was sure to produce no thrust because it was simply a 50 Ohm RF load. This load was simply a resistive load meaning that all it would do was heat up like a heating element. It’s well understood that a resistive load will not produce thrust when it is hit with RF energy.
The summary table above is from the full NASA paper. The last row shows the RF load test and that zero thrust was measured. All of the rows above that pertain to the two different models of EmDrive-like engines. Note that they reversed the orientation for each of the engines in the test set-up so that the thrust produced went in the opposite direction. The thrust reversed directions as expected. This is a good sanity check on the test set up.
I think the test results are looking more promising than many people think. Of course the force could still be produced by some interaction with the test environment that the researchers missed. That is why many more such tests must be run, and at different labs too, as is the normal course in science.
Regarding the science, it’s important to keep in mind that the NASA researchers are not the first to get positive results for a microwave cavity thruster. The paper notes: ”Since 2004, researchers at the Northwestern Polytechnical University (NPU) in Xi’an, Shaanxi, China, have been studying microwave-driven resonant cavity thrusters. In 2013, they published a paper that detailed their test campaign results and analysis methodology dealing with a very high powered RF resonant tapered cavity thruster prototype. … The thruster prototype was able to generate thrust magnitudes of over 700,000 micronewtons …”
700,000 micronewtons is equal to the force of .16 pounds. That is in the range where measurement errors due to instruments can be ruled out. If it is not real thrust being produced then there must be some force in play that both the Chinese researchers and NASA researchers are missing.
And of course Roger Shawyer himself, the EmDrive inventor, has also measured thrust from his propellantless engine.
I hope NASA funds a much bigger study of these types of engines soon. If these engines happen to really work, it may well be the beginning of one of the biggest technology breakthroughs of the 21st century.
August 10th, 2014
In my last post I said that NASA researchers claimed to measure thrust on an experimental propellantless device. That’s quite interesting – but many people are pointing to what at first appears to be a big hole in the study. In their testing the researchers created a second device, a null device, that some thought was not going to create any thrust. But the null device that was designed to not create thrust was not just an empty box. This device had a powered microwave cavity too, but of a design that some thought would not produce thrust. As a result, the researchers ended up creating a shoot-out between two different microwave thruster designs.
It’s wrong to assume that because the null device also appeared to produce thrust that the whole experiment is an uncalibrated mess. Instead, the researchers simply created two devices where both appeared to produce thrust. Of course it could be there is some other explanation that will be found later that caused the apparent measured thrust such as local air heating producing a force or a magnetic attraction or whatever.
More clarification about the null device testing here.
NASA needs to improve these experiments and rerun them soon. This propellentless device study has received way too much public attention now to not be investigated much more closely.
One nice thing about all of this is that NASA may now be forced to set up an exhaustive experiment to see if these propellantless device ideas can really produce any thrust. We may get a pretty clear answer soon as to whether EmDrive-type engines can really work. I can’t wait to hear the results!
I should also point out that the critics who claim to be the purely objective scientists often have their own biases. For example, Ethan Siegel, who wrote up a critique of this NASA study couldn’t help but also add: ”It is not a space engine; it is an apparatus that does nothing different from an empty container.” In other words he has already said that the device can’t work even before the research is repeated to clarify what the science really says.
When I hear physicists saying that certain technological devices are impossible, it reminds me too much of all the physicists who have said and still say that LENR (Cold Fusion) can’t work either. I’m no fan of silly claimed inventions like perpetual motion machines, but the EmDrive and LENR are both very promising and are not in this category at all. Research for both of them keeps saying that there is something to them. LENR research is much, much farther along than the EmDrive-type engine research, but they are both promising enough based on the evidence to date that they should be receiving a lot more research attention. Nay-saying scientists who pass judgement too quickly are the primary reason for the slow progress in research in both of these areas of science.
July 31st, 2014
If you have read the BTE blog for long you will know that I think the EmDrive is something that should be evaluated closely and that I think it’s promising. It is one of those inventions that much of the scientific community simply says will never work, and it even creates hostility in some quarters. After all, it’s an engine with no output port to eject propellant for generating thrust as is done with all conventional rocket and jet engines today – so many declare that such devices cannot work because the physics seem impossible.
Personally, as an engineer, I just care if something can be shown to work. The theoretical side in physics can be sorted out later. I think there is a lot of physics in our universe that we still know little about.
I email interviewed Roger Shawyer, the EmDrive inventor, here. He has doggedly stuck by his invention even while getting little money for help and while having to put up with a lot of criticism.
Anyhow – NASA has just released a paper saying that … well – they have now measured thrust on an experimental propellantless device similar to Shawyer’s! (The NASA paper is here.)
If microwave propellantless engines can really work – this has huge implications for space travel as well as for air travel on Earth. With no propellant port, it looks like an anti-gravity device. The mind boggles.
July 29th, 2014
The past was in color too! Here is how it might have looked.