@@jurajvariny6034 Funny you should mention that. There are trace amounts of hydrazine compounds in portabello mushrooms. I can totally see NileRed extracting hydrazine from mushrooms.
My college (Missouri S&T) actually had a cubesat onboard Transporter-10 earlier this year that was made to test a multi-mode engine that could switch between a cold gas and electric thruster, so this was pretty nice to see a video on! Unfortunately I didn’t get to help work on it since I joined the satellite design team fairly late, and also I believe it failed to establish contact with an Iridium satellite for comms after launch, so we couldn’t use it as we hoped
That sucks, I'm sorry... did it have passive solar panels or automatically deploying solar panels, or was it running from battery and relying on ground commands to deploy the panels? I ask because there's a (remote) chance that it might suddenly wake up and text you; weirder things have happened.
@@bewilderbeestie the power system wasn’t the issue, the faculty involved said our orbital velocity relative to the relay sats was probably different to the point that we couldn’t account for the red/blueshift in the signal frequency. That was as of early April this year, so it’s possible they’ve managed to find a workaround since then
Interesting. I did NS-10 and 11 and y’all were in that cohort as well with a new mission. Smallsat was fun, but the piles of documentation was something I could do without
Using electricity to add energy to a combusting propellant has also been explored for cannons, to "smooth out" the pressure curve (gun barrel pressure curves generally have a really high peak at the chamber, and then rapidly drop off - you *don't* get a "level", steady pressure curve that has more energy overall, but with dramatically lower peak pressures, and can be tailored to the barrel length more efficiently). This would increase velocities, reduce the need for as thick a breech (with the theoretical downside of requiring thicker barrel walls closer to the muzzle, but most cannon barrels are way overbuilt for the pressure they'll experience to decrease mechanical droop and increase heat sink capacity, so it's likely a wash or even a mass reduction overall), a less violent recoil (same total energy as youd get from the same projo at the same velocity from the same mass gun... but instead of a front end massive kick, it's more of a steady shove evened out along the entire barrel length), which makes designing recoil recuperation systems ("shock absorbers") easier because they have a lower *peak* velocity and force to handle. Problem is, it really complicates the gun design and logistics overall, and its generally easier to just make a longer barrel with a heavier recoil system, and just jam more conventional propellent in there. Especially since this really works best with a liquid propellent, and thats a PITA to deal with in the field than propellent charge bags.
@@1224chrisng Problem with that second idea is that setting off any one bag of propellant will set off all the rest of them in the chamber. But I kinda see what you're thinking, and there's existing research on it, so if you're interested go look at the WWII German "V-3" super cannon idea for a better implementation of the "ignite multiple bags of propellant at staggered times" concept. To answer your other proposal, slower burning propellants are good, but we already have and already use propellants with burn rates more or less tailored to the length of the gun barrel, so the answer is "Yes, but they're already doing that".
@@44R0NdinYep, the V-3 would have used that, however, the idea of multi-chamber guns is not exactly new. That one has been a mostly theoretical idea for a long time. You can also shape the propellant to burn increasingly faster and faster, keeping the initial pressure lower and the follow-on pressure higher, at least to some degree. But why use propellant at all when you can have a simple railgun or a coil gun? They do not need a high pressure barrel, and you could add a few small rocket engines to keep on speeding up … though that has not worked all that well in practice.
@@carlborg8023 You do realize every measuring system uses base 10 right? Using any other base will involve conversion at the end which ruins the whole point of the metric system.
@@asandax6 So? base 10 is still inferior. Even if the numeral system has too much societal inertia to change, a measuring system that operates on powers of two is superior. Obviously the regularity of the metric system is better than any weird eclectic system that has evolved naturally over centuries. But decimal itself is outright cumbersome once one has experience using anything better.
Interesting to hear Momentus mentioned. I was the head of GNC (orbits and attitude control) there while Vigoride 3, 5, and 6 were being built and flown. In addition to the MET main thrusters (we flew a redundant pair), the attitude control thrusters were resistojets running from the same supply of water propellant. Unfortunately, the de-ionized water supplier for 5 and 6 was not delivering it at the level of purity needed. We had months of frustrating intermittent clogs in the attitude control manifolds where the water flashed to steam and left solid deposits behind. The MET handled the impurities like a champ! They easily matched performance predictions from ground testing. Those were still hand-tuned prototype engines that had loads of room for design optimization. The real question was whether there were missions that really needed a thrust/efficiency tradeoff between chemical and ion engines. Most missions seem to want to push the optimization toward one end of the curve or the other (reach the target orbit quickly with chemical or minimize mass with ion). Momentus essentially ran out of money a year ago amid the general collapse of startup funding. It was a huge shame. That was an amazing engineering team with a truly unique and powerful satellite design. They just didn't have a way to raise money faster than the cost of building, testing, and launching three satellites a year burned through it!
Scott, there is an engine design that combines nuclear thermal and arcjet together into one engine. It uses the hydrogen propellant as a heat sink for an electrical generator, heating it up once, then the electricity is used to heat it up again in an arcjet. The result is an engine that gets about 1300 seconds and at twr of about five. It's basically a NERVA but with 50% better performance. It's called the Serpent engine and it was designed by the same guy that invented the Sabre engine for the Skylon. Look it up, it's interesting.
1300 s is... quite extreme. Assuming 900 s Isp for the base NTP engine (which is already high) that is still extracting at least 44 MJ per kilogram of propellant. This would definitely require multiple stages of turbines and reheating the working gas in the reactor core.
wow, thanks for the info dude, I was JUST thinking about SKYLON, that thing is a thermodynamic miracle...know anything about it , is it money holding it back or what ?
@@ashleyobrien4937 That project was not nearly as serious as it sounded, and primarily functioned as an advertisement for the SABRE air-breathing rocket technology. U.S. defense interests seem to have taken up the technology and not much has been heard about it since.
@@ashleyobrien4937 If Reaction Engines had infinite funds it might have happened, but realistically it was mostly an advertisement for their SABRE precooler tech. U.S. defense interests seem to have taken up the SABRE project and very little has been heard since.
As a young mad scientist in the mìd- 60s I made an arc-jet thruster based on a plasma- jet I saw in SciAm. The only errors was that the only liquefied gas available was FREON, and the device produced a poison gas (beautiful blue-green flame).
0:40 I was working at Rocket Research (Aerojet) in the Test Lab when these were first developed. I was a Mechanical Technician and had lots of hands on experience with Hydrazine. All of the production engines were catalyst activated monopropellant technology. We test fired these in huge walk in vacuum chambers sometimes referred to as altitude chamber testing. 4:00 That was the original prototype we called the "jelly roll". That is a Hydrazine gas generator that outputs 1800 degree Fahrenheit gasses. Hydrazine is N2H4 so the gas is hydrogen, nitrogen and ammonia.
I worked on ESSEX ( the Arcjet experiment on ARGOS) in the 1990's. It took three days to charge the batteries with enough power to run the arcjet for 15 minutes. The spacecraft was delayed so many times that the batteries were long past their used best by date. The batteries started out-gassing (explosively) and the thruster was shutdown to protect the other nine experiments on the space craft. Somewhere I have a picture of the spacecraft with arcjet firing, passing in front of the moon. It was taken from the USAF observatory on Maui. After ESSEX, the Air Force focus shifted to electromagnetic propulsion in the form of pulsed plasma thrusters
you haven't mentioned solid-arc jets. There is an arc between a solid propellant and an electrode. The arc controls the chemical reaction, otherwise the fuel is completely inert. It needs only a small current, and performs very well at small scales. Here the electricity only gives the activation energy for the fuel, most of the energy is provided by chemical reactions. But the chemical reactions cannot give themselves the activation energy so it needs a constant but small electric current to work.
When I worked on the AEHF program, AEHF flight one had a failure of the main bi-propellant engine on the spacecraft. This would have doomed the mission, except for some creative use of the other thrusters on the spacecraft. The failed main engine was not designed to gimbal, so there were 4 arc jets were used for steering. These arc jets were called on to raise the orbit and consumed the hydrazine fuel to exhaustion. The rest of the orbit raising was then done with the ion thrusters. This saved the mission (and several billion dollars). The ion thrusters were normally used for station keeping, and were very low thrust. For the orbit raising they had to operate for hours at a time during the high part of the elliptical orbit. This took months to accomplish. This raised the low part of the orbit at a rate of about 50 miles a day. Thats right: the orbit raised at about the same rate as a mule walks! (well, thats one way to look at it.)
This process works anywhere, the cooling system used in some WW2 fighters actually produced thrust from the "radiator" . The process is known as the Meredith Effect. "F. W. Meredith was a British engineer working at the Royal Aircraft Establishment (RAE), Farnborough. Reflecting on the principles of liquid cooling, he realized that what was conventionally regarded as waste heat, to be transferred to the atmosphere by a coolant in a radiator, need not be lost. The heat adds energy to the airflow and, with careful design, this may be used to generate thrust. The work was published in 1936. The phenomenon became known as the "Meredith effect" and was quickly adopted by the designers of prototype fighter aircraft then under development, including the Supermarine Spitfire and Hawker Hurricane whose Rolls-Royce PV-12 engine, later named the Merlin, was cooled by ethylene glycol. An early example of a Meredith effect radiator was incorporated in the design of the Spitfire for the first flight of the prototype on 5 March 1936."
Pretty sure the P-51 used that effect as well (at the very least on the oil cooler, but probably both oil cooler and radiator). However, later study has shown that the designs that were implemented didn't really generate any "net" thrust, instead the thrust produced was usually roughly of the same magnitude as the drag induced by the air intake for the same radiator. Now that doesn't mean it's "useless", far from it, it means that thru the effects of the cooling system operating normally you have REMOVED THE DRAG OF THE COOLING SYSTEM. If it was an air cooled engine it's the same as being able to operate with the cowl flaps fully closed for an indefinite amount of time. Air cooled engines could probably also make use of this phenomenon, with the benefit that they don't need to add any extra mass for a radiator, only add some adjustable sections to the cowling flaps. If you wanna be really really fancy, you could design it so that the cowl flaps are made of a bimetallic material (probably mostly the exit flaps, but maybe intake flaps could be also connected via a linkage), so that they automatically regulate the airflow thru the engine, both to maintain ideal operating temperature despite any operating condition and to optimize the efficiency of the Meredith effect produced by the in-cowl airflow being heated by proximity to the fins of the air-cooled engine. Too fancy for WWII probably, and it would need an override to fully open all the flaps for takeoff and/or use at WEP or to account for the use of any performance-boosting substances such as MW50 or Nitrous/nitromethane that might be used, but for most cruise conditions it would take workload off of the pilot (and cruise is where even fighter aircraft spend the majority of their operating time).
Really really want that VASIMR video! I remember reading about as a kid 15-20 years ago and I didn't really understand specific impulse, but it just sounded super cool.
When electrodes vaporize, they become fuel. I was testing plasma circuit with Microwave Transformer + 3 Microwave capacitors and I originally thought the pretty purple & green flames was burning air but after I examined my copper electrodes I see that they vaporized and was the fuel responsible for colored flame.
Hey Scott, YES, would definitely like to hear about VASMIR (sp?) and its competitors! All the thrusters you talked about in this video are great for station keeping and maybe small payload hops around the solar system, but to actually actually go somewhere with payload will require a much higher performance propulsion system, and that is of great interest.
Microwave thermal thrusters using water propellant are perfectly capable of getting from Earth to Mars and back, in what I can only describe as an "unconventional" spacecraft. Idea is that it's a series of double-hull inflatable habitat modules, with the inner hull containing the atmosphere and the space between hulls being used to contain the life support consumables (specifically water) used during the trip by the crew. This allows for a stupendous amount of water to be carried, which allows for mostly open-cycle life support to be used. The key that makes this work is WHERE the "open end" of the life support loop leads. It leads right to solar powered microwave thermal thrusters, which heat the wastewater (minus separable solids), and waste gases of the life support system. This allows for a constant if small amount of thrust which is still a lot better than any known ion thruster even if the overall specific impulse is lower than a nuclear thermal rocket engine. The key is that we can do it with TODAY'S tech, we don't need to wait for the design, approval, TEST LAUNCH approval, in-orbit testing, final design adjustments, and "OK now we're gonna use it for real, what do you mean it's been 8 years and the next president doesn't want to do that anymore" actual mission approval which would be required for a Nuclear Thermal Rocket (and you can almost guarantee someone's gonna not have sufficient education on nuclear tech and go "Nuclear? No no no!" no matter how calmly and plainly you explain it, and no matter how much you dumb it down so that a 3 year old can understand it (the older you get, the easier it is to fall into the "Nope, I don't like it, so I'm intentionally going to not understand it" thought trap). We can design it TODAY, have it built TOMORROW, and be off to mars by NEXT YEAR if we only want to visit Mars orbit with a manned mission. Or you know, NASA could make everyone drag their feet and congress/senate could hamstring it and it takes 20 years when it should have taken 2, but I prefer to be optimistic. Point is, all the stuff needed is ALREADY at a sufficient TRL to just say "Ok we're using this, it's been proven to work, now let's actually do it". Oh and if you're worried about radiation, you can forget about that concern. The amount of water needed is such that the water itself will be the radiation shield, and it's such a good radiation shield that the habitat doesn't even need a "storm cellar" in order to be reasonably (even by NASA standards) safe from a solar storm.
@44R0Ndin Doesn't "constant, if small thrust" = artificial gravity? I've seen this double hull, water filled construction, for decades and like it. The microwave thrusters is a new twist that I like. Sorry, though, I can't help but be a pessimist, my blood type is B-.
@@tomfrazer1428 I hesitate to call it "artificial gravity" because it's NOT gravity, it's just acceleration, but in a few words "yes but the thrust is more on the order of an ion drive, not at all adequate to fight the effects of living in freefall for extended periods". In (many) more words: The term I prefer to use is "Thrust replacing gravity", or if in a spinning habitat module, "Centrifugal forces replacing gravity". "Artificial gravity" is a term I save for use when you're creating REAL gravity (with the warping of spacetime), without the mass usually used to create said gravity. So, technically, the Alcubierre drive (the only known concept we have for a "warp drive" like used famously in Star Trek), would use a form of "artificial gravity" combined with "artificial Anti-gravity" to warp space around itself such that it is caused to accelerate relative to an external observer purely by the warping of the fabric of space-time, rather than any propulsive effort exerted by any other method, most commonly by Newtonian reaction thrusters of varying power, complexity, and efficiency (this covers anything from cold gas thrusters to solid or liquid fuel rockets to nuclear rockets and even ion drives).
@44R0Ndin I like your descriptions for the various types of forces replacing gravity. I assumed (I know, a mistake) that there would be multiple drives on a ship carrying crew, as opposed to a probe, increasing thrust/acceleration or the drive would be designed large enough to provide up to .5G. Continuous thrust with a flip over half way to the target.
@@tomfrazer1428 The issue isn't "more engines", it's "more power", and this craft's whole point is "you don't need to minimize weight to get there safely". It's a "slow boat" type of trip, there is no thrust gravity, it's using one or more microwave electrothermal thrusters, not "sci-fi physics-ignoring TIE fighter ion drives which have some handwaved incredibly powerful energy source which lets them dump so much power into the thrusters that you get space-fighter levels of performance". Reality is not nearly so kind to propulsion engineers. Solar intensity on the earth's surface is around 1kw per square meter, yeah it's higher than that in space because the atmosphere's in the way, but it's only like 1.3kw/sq.meter in earth orbit. Solar panels are at best maybe 35% efficient even with state-of-the-art cutting edge "this is the best NASA can get for their spacecraft" solar panels. And the solar intensity at Mars is significantly less than at Earth, due to being further from the Sun. So at Earth, you can put a square meter of solar panels out in orbit, and point it perfectly so that it intercepts the most of the Sun's light as possible... and you're still only getting 1.3kw*0.35= a measly 455 watts per square meter of solar panels. That's assuming those panels are NEW, and not damaged by the constant high (and occasionally extremely intense) radiation environment of space, which damages ANY semiconductor device, including solar panels and unprotected computers. Now, why does that low amount of power matter? Well, the ISS solar arrays have a total area of 150 square meters, which at the stated 35% efficiency figure putting out 455 watts per square meter, gives you (150 x 455 / 1000 for kilowatts ouput instead of watts = 68.25) 68.25 Kilowatts, divided by 2 to account for being in Earth's shadow roughly half an orbit, = 34.125 kilowatts, which aligns well with the stated "roughly 30 kilowatts plus margin" of power that the ISS was able to provide to ALL the systems on board, when the solar arrays were BRAND NEW. EACH of the solar array wings of the ISS weighs 7.71 metric tons, times 4 for how many solar array wing sections there are on the ISS, gives a mass of 30.84 metric tons for the entire solar array wing complement of the ISS, including hardware used to aim the solar arrays at the Sun. This gives us the info needed to figure out how much mass is required per kilowatt of solar panels, assuming similar construction to the panels used on the ISS, by simply taking the mass of the ISS solar arrays and dividing by their average power output in earth orbit (and if we assume operation in deep space, we would double the power before doing this calculation). For Earth Orbit, I get (30.84 mT / 34.125 kW = 0.9037 mT/kW), roughly 900 kilograms per kilowatt output. For Deep Space, I get (30.84mT / 68.25 kW = 0.4518 mT/kW) roughly 450 kilograms per kilowatt output. This matters a lot because no matter your propulsion system, if everything is held constant, increasing the mass lowers the acceleration. Ion thrusters are MASSIVE power hogs, itty bitty thrust but EXTREMELY high power usage. The ones that "barely even push" on the various ion engine propelled space probes we've launched? Each and every one of those uses over 2 kilowatts for that single thruster that usually puts out about the same thrust force as the gravity force of a sheet of paper resting on a table. Microwave electrothermal thrusters have a much lower specific impulse, so their thrust is indeed better given the same amount of input power, but keep in mind that we've got like 30-40 tons of water as a radiation shield around our habitat modules, and the rest of the habitat probably weighs on the order of 20 tons, and then we'll probably need a whopping 300kw of solar power in deep space, which will mass (at 900kg/kilowatt) 135 metric tons, but I'll be generous and assume that we've had a breakthru in that area and now solar arrays only need to mass half what they would when the ISS was constructed in orbit, so that's 67.5 tons for the solar arrays. Those space probes generally have a mass of "a few tons", let's be really generous to the mars mission by saying that a large ion-powered space probe weighs 4 metric tons. That's still not helping things much, because our mars spacecraft is a behemoth by comparison, weighing in at 40t (water) +20t (habitat and systems) +67.5t (solar arrays) = 127.5 tons. Let's say that 4 ton space probe used an ion thruster with a thrust equal to the gravitational force exerted on a sheet of paper at ground level on Earth. A sheet of A4 (similar to Letter) paper has a typical mass of 4.97 grams. Multiply by earth's gravitational acceleration of 9.81m/s^2 and you get a force of 0.0487 newtons, or 48.7 milinewtons. Now, I said that thruster used roughly 2 kilowatts, and we have 300 kilowatts. That means we need to multiply this thrust by 150 to start. 48.7 x 150 = 7,305 milinewtons or 7.305 Newtons of thrust for a 300 kw ion thruster. Now to account for the differences between microwave electrothermal thrusters and ion thrusters, we can say that the thrust and mass flow rates are roughly 10 times greater. So that gives us a thrust force of 73.05 Newtons for the 300kw-class microwave electrothermal thruster. 73.05 Newtons acting on a mass of 127.5 metric tons needs some unit conversion before it "just works", by converting metric tons to kilograms again. 127.5 mT = 127,500 Kilograms (just multiply by 1000). Now, F= MA, but rearranging it we get A= F/M. So we have our Force, 73.05 Newtons, and we have our Mass, 127500 Kilograms. How much Acceleration does that produce? Not anywhere near 0.5G, I can tell you that without doing the math! But I'll do it anyways: A=F/M, A = 73.05 / 127500 A = 5.729411764705882e-4 A= 0.005729 m/s^2 Now to scale that in "gees", we divide by 9.81m/s^2. A(gees)= 0.005729 / 9.81 A(gees) = 0.000584 G. 5.8 ten-thousandths of a G. Very much in "ion drive" territory, nowhere near the 0.5G doable with chemical rockets. The trip WILL be a lot shorter than just a pure Hohmann transfer ("slow boat" coasting to Mars), but it's still not going to be "take a few days" and you're not going to notice the acceleration pushing you in any particular direction.
You're an excellent teacher Mr Manly. You break some really complicated physics down so just a common sod like myself 😂 can better grasp the principals. It's a good part of why I so enjoy this channel. I learn something nearly every time.
A age ago I did actually try to build a fart-rocket. One of the big things that taught dumb kid me, "there is a point where you will know just enough to be absolutely wrong".
There's a filk song where poor spacers decry having to get home on a wake of foam....their engine was destroyed by pirates and their only option is to jettison their cargo of beer through the engine exhaust nozzles. Leslie Fish was the artist IIRC.
I remember hype about VASIMR several years ago. ISS was supposed to be equipped with one of Ad Astra's engines for testing purposes. But since then, nada. I guess they found that making an exotic drive is not easy.
IIRC According to James Dewar's book "To the end of the solar system" (which is about nuclear thermal rocket systems, NERVA/ROVER in particular) a good rule of thumb is 75lbs of thrust to the megawatt. NERVA was about 1.1GW and ~75,000 lbs of thrust with an ISP about 900.
This video is particularly cool for me because I got to "help a little" with the arcjet and others when I was at Rocket Research, now called Aerojet. I just loved that place!!
Can we hear about some of the more exotic electric thrusters? VASMIR is cool, and so are other electrodeless Lorentz force thrusters. my favorite thing about them is that there are no electrodes so you can use pure oxygen as the propellant, which would be the main waste product from moon mining. I also always like the idea of nuclear electrothermal where you use a nuclear reactor to generate electricity and preheat propellent for an electrothermal thruster like an arcjet or induction thruster.
DARPA experimented with this in artillery, as Electrothermal Chemical (ETC) projectiles. It was a big idea a couple of decades ago and is entirely silent now.
I helped develop a Microwave Electrothermal Thruster at the University of Surrey's Spacecraft Electric Propulsion Lab a few years ago. We're also developing a Radiofrequency Electrothermal Thruster, Microwave Airbreathing Cathode, External Plasma Thruster and Microwave ECR Magnetic Nozzle Thruster. Helicity Space are working on a really intresting fusion propulsion system that they presented a few weeks ago at the International Electric Propulsion Conference. Would be intresting to see your take on this.
So basically, the arc-jet is based on a plasma cutter nozzle. Back when I used to use one all the time, I wondered if it could be used for propulsion. Very cool!
Good to see the progress made in these areas. I wrote a review article on Electric Propulsion for Small Satellites in the Aeronautical Journal in 1991...... beyond arcjets, resistojets and ion thrusters (electrostatic and Hall-effect) there are also a couple more exotic types - magnetoplasmadynamic arcjets and colloid thrusters, would be fun for you to cover them sometime
Speaking of Hall effect thrusters, this is what they use for stationkeeping on the current Chinese space station. They solved the problem of throat erosion using magnetic confinement and a ceramic deflector to control the flow of plasma through the thruster throat. This is the first time Hall-effect thrusters have been used on a human rated spacecraft, and similar thrusters are planned to be used on the Lunar Gateway.
These porn bots are out of control. It's been YEARS and RUclips has done NOTHING. I report them every time and the same accounts with the same pictures just keep flooding every video with the same script as soon as they drop. Wtf, it's almost like they WANT them here at this point.
I’d be willing to bet they include all the bot engagement in their viewer stats when they price out their advertising. Inflating the numbers equals more profit. Means RUclips is crawling with bots.
Why so mad about them? They usually leave positive comments and are easily ignored. The toxic aggressive comments sponsored by hostile governments to spread propaganda and negativity are much worse.
Those resistojets and arcjets you showed with Aerojet logos were originally developed by a company called "Rocket Research Company". Good shop until (like many other aerospace companies in the '90s) it started get traded/bought/split up. The original Iridium spacecraft used the MR-501 resistojet, I helped develop and produce the variant used for them.
Man, I wish the "Puff" engine in KSP was this. Getting another 10-20 ISP out of monopropellant in exchange for a chunk of electricity would make that engine kinda good.
So, an ArcJet is simply a Plasma Cutter (Even the nozzle design inside looks similar) but used to generate thrust instead of cutting metal. Even the vortex gas injection is the same as in plasma cutters (they use a ceramic vortex ring with angled gas channels that generate a gas vortex inside the nozzle). That means it probably has problems with nozzle and electrode usage, which would limit its operating lifetime. Nozzles and electrodes in plasma cutting get used up PRETTY QUICKLY... Asking, cause I work with cnc plasma cutters and I'm just curious. Edit: Just watched further and you talk about the issue of nozzle and electrode corrosion. So, good to know my hunch was right ;P
Yup. The plasma cutter uses the thrust and the heat to melt the metal in a very finely controlled spot. Making us mere humans believe it has cut the metal instead of torch cutting
Thank you for your wonderful presentation at Chabot Space and science center, taking the time to share your enthusiasm with my son, and being so excited to photograph the arc thruster ring, then using it in a video. 😂
I can’t help but think of Ram and Scram jets as I learned about this. Sure they differ wildly, being that one is a Jet and the other is a rocket, but the principles are similar. You have air being pushed into the jet, being compressed, then you inject fuel into the compressed air, combusting the fuel, and heating the compressed air up, causing it to expand, and be pushed out the back faster than it had entered. The electro thermo and Nuclear Rockets work similarly, having fuel pushed into the chamber, heated up, and pushed out faster than it entered.
Speaking of "poop rockets" Scott, here's an odd corner of space industry history that might make an entertaining video: Monex. Monex was essentially a chemical rocket fuel made from spacecraft waste products such as urine, faeces, waste food, personal hygene waste etc... that would be processed _in space_ into a thick, rubbery material that burned very well. It was invented by the Rocket Research Corportation in Washington, founded by a group of ex-Boeing engineers and led by Robert M.Bridgforth Jr, who had been head of propulsion research at Boeing and had formerly worked on the Manhattan Project during the war.
When he said that waste products from humans could be used to propel a spacecraft I had the following news title in mind "Constipated astronaut stuck in space, no propellant produced"
You can make some incredibly powerful projectile launchers with those electrothermal arc jet plasma sources. I managed to launch a .2g airsoft BB at more than 2km/s with a capacitor bank made of electrolytic capacitors with only 4kJ of storage.
Was the point of the experiment just to demonstrate that the launch system could provide that acceleration & velocity to prove the launch system? Or is the launch system a means to an end, in order to hit something with a projectile at 2km/s?
There are also electric thrusters with solid fuel, like teflon block spring loaded to pair of electrodes, where electric arc is produced. This is probably the simplest electric rocket engine, because handling solid teflon block is easier than gas or liquid. It's quite popular on small satelites.
If you want to avoid the issue of throat erosion, @Scott Manley, then incorporate into the design of rocket-motor electromagnetic coils to create a containment field the prevents contact of the plasma with the interior surfaces of the thruster chamber.
There are analytical machines called ICPMS. That stands for Inductively Coupled Plasma Mass Spectroscopy. It injects a sample into the chamber and atomizes it with an induction coil and the atoms then go through a mass spectrometer.
When you said that we can even use "human waste" as propellant, I had a "vision"! ! Imagine the commander of a spaceship announcing to his crew the need to make maneuvers and therefore the need to flush the toilet. . . to save "classic" fuel... ... .😄😆😅🤣😂 Master Scott Manley you put me in a very good mood for the day! Thanks a lot 👌👌👌👍
Awesome video! It occurs to me that these could be great for cheap, semi-disposable small craft powered by beamed power using lasers. Without the need for an onboard power source, instead PV panels much smaller than using straight solar, their simplicity really shines. Or, you could have one as a sort of backup on a manned capsule, for if more complicated systems failed.
A laser to heat the gas makes sense to me, can be quite efficient, located outside the chamber and kept nice and cool. Once plasma is formed it becomes opaque to light therefore absorbing more of the energy.
funny thing about arcjet life most of the electrode erosion is caused by the start process and very little is caused by running, so arcjet life is actually limited by the number of starts you want to do as opposed to the total run time.
So a TIG welding nozzle as a rocket motor? OK! This does make me wonder if you could do a secondary acceleration ionically, since you're cranking potentially plasma level temps, you've got an ionized gas to work with.
The microwave electro driven rocket sounds like you could gather up space debris and it could turn it into plasma and then into thrust. Just imagine gathering up that small test reactor that's in a storage orbit for an initial energy source. Then you could have an energy source that could even turn a dusty asteroid into plasma. You can divert its course or use it to travel places. I'm sure it's not very efficient but I can dream.
An interesting theoretical use case for arcjets could be to boost the specific impulse of a nuclear-thermal engine. The idea would be that you send the hydrogen through the core twice (or even more times). After the first run through, at high pressure, and perhaps through a lower-temperature section of the core, it enters a turbine, where it expands and does work. This lower-pressure hydrogen is then routed through the reactor again, heated to the typical 3000 K maximum for a solid core NTE - and then the work it did in the turbine(s) is used to drive a secondary arcjet chamber to heat it to perhaps 4000 K, giving a nice 15% or so boost to Isp, admittedly at the cost of a much more complex and heavier engine.
Integza did a video about a really cool solid rocket fuel that is great for thrusters it is ignited electrically but will only burn as long as the current is applied. Pretty much a solid fueled resistor jet.
What about using freakin lasers to heat the fuel up? You could use directionality to determine chamber pressure. And with a sufficiently advanced system you could make sure every photon is hitting a gas particle.
This is so cool! If you can get nuclear thermal rocket performance with these imagine scaling one of these elector thermal thrusters up and using a nuclear reactor to power it. I wonder if it would have enough thrust to get to orbit and I wonder if you can use the atmosphere as the propellant gas at lower altitudes
1 eV is 11606 K. The main issue is that you need to ionize the propellant first. If you take a potassium or cesium ion and accelerated with 100 volts it's exhaust temperature is 1.16 million Kelvin.
While I was TIG-welding in school, I did have the idea of adapting it to a rocket engine working basically as a Arcjet, and then immediately stopped that train of thought because it was a obvious idea and the fact that I'd never read about any of them would imply there's reasons to not do it. Good to know now WHY its not common at least.
Got a vision now of an elderly astronaut standing in his garden, looking up at a fast-moving "star" in the night sky, with his hand on his grandson's shoulder, saying, "See that son? That's the space station. I kept that in orbit for twenty years with my farts, so the next time your mum complains about them, you just remember that..."
NileRed: So I was watching Scott Manley when I got an idea...
*zooms on 1:29
Poopulsion
I keep waiting for the day he makes hydrazine. I'm sure it will happen one day.
But he would use pee, not hydrazine
@@jurajvariny6034 Funny you should mention that. There are trace amounts of hydrazine compounds in portabello mushrooms. I can totally see NileRed extracting hydrazine from mushrooms.
@@jurajvariny6034 Or he would make hydrazine from pee.
My college (Missouri S&T) actually had a cubesat onboard Transporter-10 earlier this year that was made to test a multi-mode engine that could switch between a cold gas and electric thruster, so this was pretty nice to see a video on! Unfortunately I didn’t get to help work on it since I joined the satellite design team fairly late, and also I believe it failed to establish contact with an Iridium satellite for comms after launch, so we couldn’t use it as we hoped
That sucks, I'm sorry... did it have passive solar panels or automatically deploying solar panels, or was it running from battery and relying on ground commands to deploy the panels? I ask because there's a (remote) chance that it might suddenly wake up and text you; weirder things have happened.
Which mission was it? Was it a UNP mission?
@@bewilderbeestie the power system wasn’t the issue, the faculty involved said our orbital velocity relative to the relay sats was probably different to the point that we couldn’t account for the red/blueshift in the signal frequency. That was as of early April this year, so it’s possible they’ve managed to find a workaround since then
@@MoonWeasel23 yea it was UNP, the mission name was M^3, which stands for Multi-Mode Mission
Interesting. I did NS-10 and 11 and y’all were in that cohort as well with a new mission. Smallsat was fun, but the piles of documentation was something I could do without
Using electricity to add energy to a combusting propellant has also been explored for cannons, to "smooth out" the pressure curve (gun barrel pressure curves generally have a really high peak at the chamber, and then rapidly drop off - you *don't* get a "level", steady pressure curve that has more energy overall, but with dramatically lower peak pressures, and can be tailored to the barrel length more efficiently).
This would increase velocities, reduce the need for as thick a breech (with the theoretical downside of requiring thicker barrel walls closer to the muzzle, but most cannon barrels are way overbuilt for the pressure they'll experience to decrease mechanical droop and increase heat sink capacity, so it's likely a wash or even a mass reduction overall), a less violent recoil (same total energy as youd get from the same projo at the same velocity from the same mass gun... but instead of a front end massive kick, it's more of a steady shove evened out along the entire barrel length), which makes designing recoil recuperation systems ("shock absorbers") easier because they have a lower *peak* velocity and force to handle.
Problem is, it really complicates the gun design and logistics overall, and its generally easier to just make a longer barrel with a heavier recoil system, and just jam more conventional propellent in there. Especially since this really works best with a liquid propellent, and thats a PITA to deal with in the field than propellent charge bags.
My wife brings me a seemingly never ending quantity of charged bags.
Fascinating. Can you tell the name of the program of give a source for additional reading material?
can't you achieve the same thing with a slower burning propellant? or maybe just light the multiple bags of propellants at staggered times?
@@1224chrisng Problem with that second idea is that setting off any one bag of propellant will set off all the rest of them in the chamber.
But I kinda see what you're thinking, and there's existing research on it, so if you're interested go look at the WWII German "V-3" super cannon idea for a better implementation of the "ignite multiple bags of propellant at staggered times" concept.
To answer your other proposal, slower burning propellants are good, but we already have and already use propellants with burn rates more or less tailored to the length of the gun barrel, so the answer is "Yes, but they're already doing that".
@@44R0NdinYep, the V-3 would have used that, however, the idea of multi-chamber guns is not exactly new. That one has been a mostly theoretical idea for a long time.
You can also shape the propellant to burn increasingly faster and faster, keeping the initial pressure lower and the follow-on pressure higher, at least to some degree.
But why use propellant at all when you can have a simple railgun or a coil gun? They do not need a high pressure barrel, and you could add a few small rocket engines to keep on speeding up … though that has not worked all that well in practice.
That graph with lbf thrust and propellant kg broke my brain
Yeah Americans need to permanently switch to metric and stop using pounds per square burger. They also should start getting over their foot fetish.
@@asandax6There's nothing wrong with feet 😂 but yes full metric
@@asandax6 Only if the metric system changes to a better number base than ten. The _worst_ number base.
@@carlborg8023 You do realize every measuring system uses base 10 right? Using any other base will involve conversion at the end which ruins the whole point of the metric system.
@@asandax6 So? base 10 is still inferior. Even if the numeral system has too much societal inertia to change, a measuring system that operates on powers of two is superior. Obviously the regularity of the metric system is better than any weird eclectic system that has evolved naturally over centuries. But decimal itself is outright cumbersome once one has experience using anything better.
Colab with NileRed when???
“Turning plastic bags into rocket fuel”
No thanks.
"Today we're going to be making Jacked Buffalo Ranch Doritos out of hydrazine"
@mrgreenguy “I made hypergolic rocket fuel in my dog house”
"Turning hydrazine into pop rocks"
Interesting to hear Momentus mentioned. I was the head of GNC (orbits and attitude control) there while Vigoride 3, 5, and 6 were being built and flown.
In addition to the MET main thrusters (we flew a redundant pair), the attitude control thrusters were resistojets running from the same supply of water propellant.
Unfortunately, the de-ionized water supplier for 5 and 6 was not delivering it at the level of purity needed. We had months of frustrating intermittent clogs in the attitude control manifolds where the water flashed to steam and left solid deposits behind.
The MET handled the impurities like a champ! They easily matched performance predictions from ground testing. Those were still hand-tuned prototype engines that had loads of room for design optimization. The real question was whether there were missions that really needed a thrust/efficiency tradeoff between chemical and ion engines. Most missions seem to want to push the optimization toward one end of the curve or the other (reach the target orbit quickly with chemical or minimize mass with ion).
Momentus essentially ran out of money a year ago amid the general collapse of startup funding. It was a huge shame. That was an amazing engineering team with a truly unique and powerful satellite design. They just didn't have a way to raise money faster than the cost of building, testing, and launching three satellites a year burned through it!
Scott, there is an engine design that combines nuclear thermal and arcjet together into one engine. It uses the hydrogen propellant as a heat sink for an electrical generator, heating it up once, then the electricity is used to heat it up again in an arcjet. The result is an engine that gets about 1300 seconds and at twr of about five. It's basically a NERVA but with 50% better performance. It's called the Serpent engine and it was designed by the same guy that invented the Sabre engine for the Skylon. Look it up, it's interesting.
...Wow. That is sci-fi level performance.
1300 s is... quite extreme. Assuming 900 s Isp for the base NTP engine (which is already high) that is still extracting at least 44 MJ per kilogram of propellant. This would definitely require multiple stages of turbines and reheating the working gas in the reactor core.
wow, thanks for the info dude, I was JUST thinking about SKYLON, that thing is a thermodynamic miracle...know anything about it , is it money holding it back or what ?
@@ashleyobrien4937 That project was not nearly as serious as it sounded, and primarily functioned as an advertisement for the SABRE air-breathing rocket technology. U.S. defense interests seem to have taken up the technology and not much has been heard about it since.
@@ashleyobrien4937 If Reaction Engines had infinite funds it might have happened, but realistically it was mostly an advertisement for their SABRE precooler tech. U.S. defense interests seem to have taken up the SABRE project and very little has been heard since.
Finally, Scott has covered the optimal means of space propulsion: the REPISSTOJET!
As a young mad scientist in the mìd- 60s I made an arc-jet thruster based on a plasma- jet I saw in SciAm.
The only errors was that the only liquefied gas available was FREON, and the device produced a poison gas (beautiful blue-green flame).
One would assume these chlorine and fluorine atoms would rather go some place else once given the opportunity. What kind of gas does it make exactly?
It produces Phosgene gas, doesn’t it?
60s rocket engineering at it's finest.
everything in the 60s makes phosgene if you make it angry @@c.hibdon1628
@@KR4FTW3RKI'm gonna guess there's a non insignificant amount of HF 😰
0:40 I was working at Rocket Research (Aerojet) in the Test Lab when these were first developed. I was a Mechanical Technician and had lots of hands on experience with Hydrazine. All of the production engines were catalyst activated monopropellant technology. We test fired these in huge walk in vacuum chambers sometimes referred to as altitude chamber testing. 4:00 That was the original prototype we called the "jelly roll". That is a Hydrazine gas generator that outputs 1800 degree Fahrenheit gasses. Hydrazine is N2H4 so the gas is hydrogen, nitrogen and ammonia.
Always wanted to try to make a resistor rocket to decompose hydrogen peroxide. A spicy steam rocket.
I worked on ESSEX ( the Arcjet experiment on ARGOS) in the 1990's. It took three days to charge the batteries with enough power to run the arcjet for 15 minutes. The spacecraft was delayed so many times that the batteries were long past their used best by date. The batteries started out-gassing (explosively) and the thruster was shutdown to protect the other nine experiments on the space craft. Somewhere I have a picture of the spacecraft with arcjet firing, passing in front of the moon. It was taken from the USAF observatory on Maui.
After ESSEX, the Air Force focus shifted to electromagnetic propulsion in the form of pulsed plasma thrusters
you haven't mentioned solid-arc jets.
There is an arc between a solid propellant and an electrode. The arc controls the chemical reaction, otherwise the fuel is completely inert.
It needs only a small current, and performs very well at small scales.
Here the electricity only gives the activation energy for the fuel, most of the energy is provided by chemical reactions. But the chemical reactions cannot give themselves the activation energy so it needs a constant but small electric current to work.
Integza did a video on those, really cool stuff
When I worked on the AEHF program, AEHF flight one had a failure of the main bi-propellant engine on the spacecraft. This would have doomed the mission, except for some creative use of the other thrusters on the spacecraft. The failed main engine was not designed to gimbal, so there were 4 arc jets were used for steering. These arc jets were called on to raise the orbit and consumed the hydrazine fuel to exhaustion. The rest of the orbit raising was then done with the ion thrusters. This saved the mission (and several billion dollars). The ion thrusters were normally used for station keeping, and were very low thrust. For the orbit raising they had to operate for hours at a time during the high part of the elliptical orbit. This took months to accomplish. This raised the low part of the orbit at a rate of about 50 miles a day. Thats right: the orbit raised at about the same rate as a mule walks! (well, thats one way to look at it.)
I love the educational videos over the "check-in" videos. Some of my favorites are on the older tech in the Apollo and Shuttle eras.
This process works anywhere, the cooling system used in some WW2 fighters actually produced thrust from the "radiator" . The process is known as the Meredith Effect.
"F. W. Meredith was a British engineer working at the Royal Aircraft Establishment (RAE), Farnborough. Reflecting on the principles of liquid cooling, he realized that what was conventionally regarded as waste heat, to be transferred to the atmosphere by a coolant in a radiator, need not be lost. The heat adds energy to the airflow and, with careful design, this may be used to generate thrust. The work was published in 1936.
The phenomenon became known as the "Meredith effect" and was quickly adopted by the designers of prototype fighter aircraft then under development, including the Supermarine Spitfire and Hawker Hurricane whose Rolls-Royce PV-12 engine, later named the Merlin, was cooled by ethylene glycol. An early example of a Meredith effect radiator was incorporated in the design of the Spitfire for the first flight of the prototype on 5 March 1936."
Pretty sure the P-51 used that effect as well (at the very least on the oil cooler, but probably both oil cooler and radiator).
However, later study has shown that the designs that were implemented didn't really generate any "net" thrust, instead the thrust produced was usually roughly of the same magnitude as the drag induced by the air intake for the same radiator.
Now that doesn't mean it's "useless", far from it, it means that thru the effects of the cooling system operating normally you have REMOVED THE DRAG OF THE COOLING SYSTEM. If it was an air cooled engine it's the same as being able to operate with the cowl flaps fully closed for an indefinite amount of time.
Air cooled engines could probably also make use of this phenomenon, with the benefit that they don't need to add any extra mass for a radiator, only add some adjustable sections to the cowling flaps.
If you wanna be really really fancy, you could design it so that the cowl flaps are made of a bimetallic material (probably mostly the exit flaps, but maybe intake flaps could be also connected via a linkage), so that they automatically regulate the airflow thru the engine, both to maintain ideal operating temperature despite any operating condition and to optimize the efficiency of the Meredith effect produced by the in-cowl airflow being heated by proximity to the fins of the air-cooled engine. Too fancy for WWII probably, and it would need an override to fully open all the flaps for takeoff and/or use at WEP or to account for the use of any performance-boosting substances such as MW50 or Nitrous/nitromethane that might be used, but for most cruise conditions it would take workload off of the pilot (and cruise is where even fighter aircraft spend the majority of their operating time).
"Merlin engine" sounds familiar )
@@artemkras Yeah, that "later named the Merlin" was like a mini mind-blow 🤯
Really really want that VASIMR video! I remember reading about as a kid 15-20 years ago and I didn't really understand specific impulse, but it just sounded super cool.
When electrodes vaporize, they become fuel. I was testing plasma circuit with Microwave Transformer + 3 Microwave capacitors and I originally thought the pretty purple & green flames was burning air but after I examined my copper electrodes I see that they vaporized and was the fuel responsible for colored flame.
Microwave transformers are scary dangerous.
Ah yes, the famous engine rich exhaust
@@Johnny_OSG 😂 I admit you got a laugh outta me with that one.
"Mixture full rich! Mixture full lean! Mixture...engine...rich?"
10:00 "...or get rid of the heating element entirely" That is such a fine explanation!
Hey Scott, YES, would definitely like to hear about VASMIR (sp?) and its competitors! All the thrusters you talked about in this video are great for station keeping and maybe small payload hops around the solar system, but to actually actually go somewhere with payload will require a much higher performance propulsion system, and that is of great interest.
Microwave thermal thrusters using water propellant are perfectly capable of getting from Earth to Mars and back, in what I can only describe as an "unconventional" spacecraft. Idea is that it's a series of double-hull inflatable habitat modules, with the inner hull containing the atmosphere and the space between hulls being used to contain the life support consumables (specifically water) used during the trip by the crew.
This allows for a stupendous amount of water to be carried, which allows for mostly open-cycle life support to be used.
The key that makes this work is WHERE the "open end" of the life support loop leads. It leads right to solar powered microwave thermal thrusters, which heat the wastewater (minus separable solids), and waste gases of the life support system.
This allows for a constant if small amount of thrust which is still a lot better than any known ion thruster even if the overall specific impulse is lower than a nuclear thermal rocket engine. The key is that we can do it with TODAY'S tech, we don't need to wait for the design, approval, TEST LAUNCH approval, in-orbit testing, final design adjustments, and "OK now we're gonna use it for real, what do you mean it's been 8 years and the next president doesn't want to do that anymore" actual mission approval which would be required for a Nuclear Thermal Rocket (and you can almost guarantee someone's gonna not have sufficient education on nuclear tech and go "Nuclear? No no no!" no matter how calmly and plainly you explain it, and no matter how much you dumb it down so that a 3 year old can understand it (the older you get, the easier it is to fall into the "Nope, I don't like it, so I'm intentionally going to not understand it" thought trap).
We can design it TODAY, have it built TOMORROW, and be off to mars by NEXT YEAR if we only want to visit Mars orbit with a manned mission.
Or you know, NASA could make everyone drag their feet and congress/senate could hamstring it and it takes 20 years when it should have taken 2, but I prefer to be optimistic.
Point is, all the stuff needed is ALREADY at a sufficient TRL to just say "Ok we're using this, it's been proven to work, now let's actually do it".
Oh and if you're worried about radiation, you can forget about that concern. The amount of water needed is such that the water itself will be the radiation shield, and it's such a good radiation shield that the habitat doesn't even need a "storm cellar" in order to be reasonably (even by NASA standards) safe from a solar storm.
@44R0Ndin Doesn't "constant, if small thrust" = artificial gravity? I've seen this double hull, water filled construction, for decades and like it. The microwave thrusters is a new twist that I like.
Sorry, though, I can't help but be a pessimist, my blood type is B-.
@@tomfrazer1428
I hesitate to call it "artificial gravity" because it's NOT gravity, it's just acceleration, but in a few words "yes but the thrust is more on the order of an ion drive, not at all adequate to fight the effects of living in freefall for extended periods".
In (many) more words:
The term I prefer to use is "Thrust replacing gravity", or if in a spinning habitat module, "Centrifugal forces replacing gravity".
"Artificial gravity" is a term I save for use when you're creating REAL gravity (with the warping of spacetime), without the mass usually used to create said gravity.
So, technically, the Alcubierre drive (the only known concept we have for a "warp drive" like used famously in Star Trek), would use a form of "artificial gravity" combined with "artificial Anti-gravity" to warp space around itself such that it is caused to accelerate relative to an external observer purely by the warping of the fabric of space-time, rather than any propulsive effort exerted by any other method, most commonly by Newtonian reaction thrusters of varying power, complexity, and efficiency (this covers anything from cold gas thrusters to solid or liquid fuel rockets to nuclear rockets and even ion drives).
@44R0Ndin I like your descriptions for the various types of forces replacing gravity. I assumed (I know, a mistake) that there would be multiple drives on a ship carrying crew, as opposed to a probe, increasing thrust/acceleration or the drive would be designed large enough to provide up to .5G. Continuous thrust with a flip over half way to the target.
@@tomfrazer1428
The issue isn't "more engines", it's "more power", and this craft's whole point is "you don't need to minimize weight to get there safely".
It's a "slow boat" type of trip, there is no thrust gravity, it's using one or more microwave electrothermal thrusters, not "sci-fi physics-ignoring TIE fighter ion drives which have some handwaved incredibly powerful energy source which lets them dump so much power into the thrusters that you get space-fighter levels of performance".
Reality is not nearly so kind to propulsion engineers. Solar intensity on the earth's surface is around 1kw per square meter, yeah it's higher than that in space because the atmosphere's in the way, but it's only like 1.3kw/sq.meter in earth orbit. Solar panels are at best maybe 35% efficient even with state-of-the-art cutting edge "this is the best NASA can get for their spacecraft" solar panels. And the solar intensity at Mars is significantly less than at Earth, due to being further from the Sun.
So at Earth, you can put a square meter of solar panels out in orbit, and point it perfectly so that it intercepts the most of the Sun's light as possible... and you're still only getting 1.3kw*0.35= a measly 455 watts per square meter of solar panels. That's assuming those panels are NEW, and not damaged by the constant high (and occasionally extremely intense) radiation environment of space, which damages ANY semiconductor device, including solar panels and unprotected computers.
Now, why does that low amount of power matter? Well, the ISS solar arrays have a total area of 150 square meters, which at the stated 35% efficiency figure putting out 455 watts per square meter, gives you (150 x 455 / 1000 for kilowatts ouput instead of watts = 68.25) 68.25 Kilowatts, divided by 2 to account for being in Earth's shadow roughly half an orbit, = 34.125 kilowatts, which aligns well with the stated "roughly 30 kilowatts plus margin" of power that the ISS was able to provide to ALL the systems on board, when the solar arrays were BRAND NEW.
EACH of the solar array wings of the ISS weighs 7.71 metric tons, times 4 for how many solar array wing sections there are on the ISS, gives a mass of 30.84 metric tons for the entire solar array wing complement of the ISS, including hardware used to aim the solar arrays at the Sun.
This gives us the info needed to figure out how much mass is required per kilowatt of solar panels, assuming similar construction to the panels used on the ISS, by simply taking the mass of the ISS solar arrays and dividing by their average power output in earth orbit (and if we assume operation in deep space, we would double the power before doing this calculation).
For Earth Orbit, I get (30.84 mT / 34.125 kW = 0.9037 mT/kW), roughly 900 kilograms per kilowatt output.
For Deep Space, I get (30.84mT / 68.25 kW = 0.4518 mT/kW) roughly 450 kilograms per kilowatt output.
This matters a lot because no matter your propulsion system, if everything is held constant, increasing the mass lowers the acceleration.
Ion thrusters are MASSIVE power hogs, itty bitty thrust but EXTREMELY high power usage.
The ones that "barely even push" on the various ion engine propelled space probes we've launched? Each and every one of those uses over 2 kilowatts for that single thruster that usually puts out about the same thrust force as the gravity force of a sheet of paper resting on a table.
Microwave electrothermal thrusters have a much lower specific impulse, so their thrust is indeed better given the same amount of input power, but keep in mind that we've got like 30-40 tons of water as a radiation shield around our habitat modules, and the rest of the habitat probably weighs on the order of 20 tons, and then we'll probably need a whopping 300kw of solar power in deep space, which will mass (at 900kg/kilowatt) 135 metric tons, but I'll be generous and assume that we've had a breakthru in that area and now solar arrays only need to mass half what they would when the ISS was constructed in orbit, so that's 67.5 tons for the solar arrays.
Those space probes generally have a mass of "a few tons", let's be really generous to the mars mission by saying that a large ion-powered space probe weighs 4 metric tons.
That's still not helping things much, because our mars spacecraft is a behemoth by comparison, weighing in at 40t (water) +20t (habitat and systems) +67.5t (solar arrays) = 127.5 tons.
Let's say that 4 ton space probe used an ion thruster with a thrust equal to the gravitational force exerted on a sheet of paper at ground level on Earth.
A sheet of A4 (similar to Letter) paper has a typical mass of 4.97 grams.
Multiply by earth's gravitational acceleration of 9.81m/s^2 and you get a force of 0.0487 newtons, or 48.7 milinewtons.
Now, I said that thruster used roughly 2 kilowatts, and we have 300 kilowatts. That means we need to multiply this thrust by 150 to start.
48.7 x 150 = 7,305 milinewtons or 7.305 Newtons of thrust for a 300 kw ion thruster.
Now to account for the differences between microwave electrothermal thrusters and ion thrusters, we can say that the thrust and mass flow rates are roughly 10 times greater.
So that gives us a thrust force of 73.05 Newtons for the 300kw-class microwave electrothermal thruster.
73.05 Newtons acting on a mass of 127.5 metric tons needs some unit conversion before it "just works", by converting metric tons to kilograms again.
127.5 mT = 127,500 Kilograms (just multiply by 1000).
Now, F= MA, but rearranging it we get A= F/M.
So we have our Force, 73.05 Newtons, and we have our Mass, 127500 Kilograms.
How much Acceleration does that produce?
Not anywhere near 0.5G, I can tell you that without doing the math!
But I'll do it anyways:
A=F/M,
A = 73.05 / 127500
A = 5.729411764705882e-4
A= 0.005729 m/s^2
Now to scale that in "gees", we divide by 9.81m/s^2.
A(gees)= 0.005729 / 9.81
A(gees) = 0.000584 G.
5.8 ten-thousandths of a G.
Very much in "ion drive" territory, nowhere near the 0.5G doable with chemical rockets.
The trip WILL be a lot shorter than just a pure Hohmann transfer ("slow boat" coasting to Mars), but it's still not going to be "take a few days" and you're not going to notice the acceleration pushing you in any particular direction.
You're an excellent teacher Mr Manly. You break some really complicated physics down so just a common sod like myself 😂 can better grasp the principals. It's a good part of why I so enjoy this channel. I learn something nearly every time.
I am forever having to pause your videos, Scott for the awesome detailed graphics you incorporate in them. Thank you.
powering a rocket with human waste products sounds like a south park bit, astronauts powering a rocket by pissing and shidding and farding
Well, it'll be a real feature in the future.
Hahaha! 😂 That seriously is 100% south park material!
A age ago I did actually try to build a fart-rocket.
One of the big things that taught dumb kid me, "there is a point where you will know just enough to be absolutely wrong".
There's a filk song where poor spacers decry having to get home on a wake of foam....their engine was destroyed by pirates and their only option is to jettison their cargo of beer through the engine exhaust nozzles.
Leslie Fish was the artist IIRC.
Imagine being the crew that has to clean the viewports.
what a crappy job.
I love that Scott could only think of Nilered when he wanted to talk about using Hydrazine cause his love for hazardous chemicals is so well known now
Nahhhh, if we’re talking love for hazardous chemicals, it’s gotta be ChemicalForce.
He also makes AMAZING slow mo shots which are very artful
Ifl chemicalforce
Except he avoided it, IIRC when he tried "playing with" rocket fuels.
That was lolworthy.
but my rocket didn't turn out as creepy as I had wanted...
@@mduckernz NileRed, ChemicalForce and Explosions&Fire are the trinity of youtube chemistry
I remember hype about VASIMR several years ago. ISS was supposed to be equipped with one of Ad Astra's engines for testing purposes. But since then, nada. I guess they found that making an exotic drive is not easy.
power requirements and mass might have prevented that
I very much want to see videos on VASIMR
Vasimr really needs superconductors to work properly. Hard to do in space, so far.
IIRC According to James Dewar's book "To the end of the solar system" (which is about nuclear thermal rocket systems, NERVA/ROVER in particular) a good rule of thumb is 75lbs of thrust to the megawatt. NERVA was about 1.1GW and ~75,000 lbs of thrust with an ISP about 900.
I've been waiting to hear you, Scott, talk about VASIMR systems in detail. So, yes, please do.
This video is particularly cool for me because I got to "help a little" with the arcjet and others when I was at Rocket Research, now called Aerojet. I just loved that place!!
Vasimr engines are the ones I've heard of but know nothing about how they work. Look forward to seeing it.
Can we hear about some of the more exotic electric thrusters? VASMIR is cool, and so are other electrodeless Lorentz force thrusters. my favorite thing about them is that there are no electrodes so you can use pure oxygen as the propellant, which would be the main waste product from moon mining.
I also always like the idea of nuclear electrothermal where you use a nuclear reactor to generate electricity and preheat propellent for an electrothermal thruster like an arcjet or induction thruster.
DARPA experimented with this in artillery, as Electrothermal Chemical (ETC) projectiles. It was a big idea a couple of decades ago and is entirely silent now.
I'm sure it's still being developed - it's such a good idea it's not going to die, but there are control problems to be ironed out.
Oh love the Nile Red call out 🤗 colab time! 🎉🎉
Found out about induction lighting system years ago and it's a very interesting subject! It's used in big public spaces lighting.
I'll have to look it up
I helped develop a Microwave Electrothermal Thruster at the University of Surrey's Spacecraft Electric Propulsion Lab a few years ago. We're also developing a Radiofrequency Electrothermal Thruster, Microwave Airbreathing Cathode, External Plasma Thruster and Microwave ECR Magnetic Nozzle Thruster.
Helicity Space are working on a really intresting fusion propulsion system that they presented a few weeks ago at the International Electric Propulsion Conference. Would be intresting to see your take on this.
So basically, the arc-jet is based on a plasma cutter nozzle. Back when I used to use one all the time, I wondered if it could be used for propulsion. Very cool!
Love the cast as always, You appear to be wearing a Dr Karl Kruszelnicki style shirt. Look him up, an Aussie thing!
Good to see the progress made in these areas. I wrote a review article on Electric Propulsion for Small Satellites in the Aeronautical Journal in 1991...... beyond arcjets, resistojets and ion thrusters (electrostatic and Hall-effect) there are also a couple more exotic types - magnetoplasmadynamic arcjets and colloid thrusters, would be fun for you to cover them sometime
Speaking of Hall effect thrusters, this is what they use for stationkeeping on the current Chinese space station. They solved the problem of throat erosion using magnetic confinement and a ceramic deflector to control the flow of plasma through the thruster throat. This is the first time Hall-effect thrusters have been used on a human rated spacecraft, and similar thrusters are planned to be used on the Lunar Gateway.
These porn bots are out of control. It's been YEARS and RUclips has done NOTHING. I report them every time and the same accounts with the same pictures just keep flooding every video with the same script as soon as they drop. Wtf, it's almost like they WANT them here at this point.
It’s a side hustle of the RUclips CEO to make some additional money.
Do you report the profiles for impersonating?
Hence. Ad blockers.
I’d be willing to bet they include all the bot engagement in their viewer stats when they price out their advertising. Inflating the numbers equals more profit. Means RUclips is crawling with bots.
Why so mad about them? They usually leave positive comments and are easily ignored. The toxic aggressive comments sponsored by hostile governments to spread propaganda and negativity are much worse.
A deep-dive into VASIMR would be fantastic!
6:11: Love the NileRed nod/reference! 😹
Those resistojets and arcjets you showed with Aerojet logos were originally developed by a company called "Rocket Research Company". Good shop until (like many other aerospace companies in the '90s) it started get traded/bought/split up. The original Iridium spacecraft used the MR-501 resistojet, I helped develop and produce the variant used for them.
Man, I wish the "Puff" engine in KSP was this. Getting another 10-20 ISP out of monopropellant in exchange for a chunk of electricity would make that engine kinda good.
So, an ArcJet is simply a Plasma Cutter (Even the nozzle design inside looks similar) but used to generate thrust instead of cutting metal. Even the vortex gas injection is the same as in plasma cutters (they use a ceramic vortex ring with angled gas channels that generate a gas vortex inside the nozzle). That means it probably has problems with nozzle and electrode usage, which would limit its operating lifetime. Nozzles and electrodes in plasma cutting get used up PRETTY QUICKLY... Asking, cause I work with cnc plasma cutters and I'm just curious.
Edit: Just watched further and you talk about the issue of nozzle and electrode corrosion. So, good to know my hunch was right ;P
Yup. The plasma cutter uses the thrust and the heat to melt the metal in a very finely controlled spot. Making us mere humans believe it has cut the metal instead of torch cutting
Thank you for your wonderful presentation at Chabot Space and science center, taking the time to share your enthusiasm with my son, and being so excited to photograph the arc thruster ring, then using it in a video. 😂
I can’t help but think of Ram and Scram jets as I learned about this.
Sure they differ wildly, being that one is a Jet and the other is a rocket, but the principles are similar.
You have air being pushed into the jet, being compressed, then you inject fuel into the compressed air, combusting the fuel, and heating the compressed air up, causing it to expand, and be pushed out the back faster than it had entered.
The electro thermo and Nuclear Rockets work similarly, having fuel pushed into the chamber, heated up, and pushed out faster than it entered.
A collaboration between Integza (the thruster aficionado) and NileRed (the walking hazard) could create some absurd rockets!
"2.21 Gigawatts! Great Scott!!"
Fascinating - I'd never heard of these things
The idea of a thruster being basically a hair dryer blowing nitrous oxide makes me giggle. 😜
Fascinating! Thanks, Scott! 😊
Stay safe there with your family! 🖖😊
Speaking of "poop rockets" Scott, here's an odd corner of space industry history that might make an entertaining video: Monex. Monex was essentially a chemical rocket fuel made from spacecraft waste products such as urine, faeces, waste food, personal hygene waste etc... that would be processed _in space_ into a thick, rubbery material that burned very well. It was invented by the Rocket Research Corportation in Washington, founded by a group of ex-Boeing engineers and led by Robert M.Bridgforth Jr, who had been head of propulsion research at Boeing and had formerly worked on the Manhattan Project during the war.
Is that why rockets go weeeeeeeeeeeee! 😋😂
@@johnruddick686
Boeing: "That's the shittiest idea we've ever seen!"
Bob Bridgeforth: "Hold my beer..."
It is one of my favourite plasma rocket engines
When he said that waste products from humans could be used to propel a spacecraft I had the following news title in mind "Constipated astronaut stuck in space, no propellant produced"
Imagine having to start your spaceship using a plunger 🪠
This was a really interesting episode! djSnM got me dancing
Nice overview Scott, thanks. Fly Safe.
You can make some incredibly powerful projectile launchers with those electrothermal arc jet plasma sources. I managed to launch a .2g airsoft BB at more than 2km/s with a capacitor bank made of electrolytic capacitors with only 4kJ of storage.
Was the point of the experiment just to demonstrate that the launch system could provide that acceleration & velocity to prove the launch system?
Or is the launch system a means to an end, in order to hit something with a projectile at 2km/s?
There are also electric thrusters with solid fuel, like teflon block spring loaded to pair of electrodes, where electric arc is produced. This is probably the simplest electric rocket engine, because handling solid teflon block is easier than gas or liquid. It's quite popular on small satelites.
Yes Please, a VASIMR video would be awesome.
really interesting thanks. There's more of this to come hopefully.
Thank you for creating and sharing this informative video. Great job. Keep it up.
Would love more videos of lesssr known engine types. Had no idea arc jet motors where a thing! Very interesting
I love Scott’s new fashion ❤️
"grams of force" is a phrase i never thought i would hear uttered
If you want to avoid the issue of throat erosion, @Scott Manley, then incorporate into the design of rocket-motor electromagnetic coils to create a containment field the prevents contact of the plasma with the interior surfaces of the thruster chamber.
There are analytical machines called ICPMS. That stands for Inductively Coupled Plasma Mass Spectroscopy. It injects a sample into the chamber and atomizes it with an induction coil and the atoms then go through a mass spectrometer.
Slowly learning how to build my rocket. Thanks Scott.
Farts keeping the ISS in orbit is a pretty funny mental picture 😅
Better out than in I say.
Very informative didn't know this was a thing ❤
08:40 "Waste gases" I want to hear the sound of the first fart propelled rocket blasting off.
13:20 That reminds me of Bill Nelson's teeth.
financed with poop crypto 💩 😅
When you said that we can even use "human waste" as propellant, I had a "vision"! !
Imagine the commander of a spaceship announcing to his crew the need to make maneuvers and therefore the need to flush the toilet. . . to save "classic" fuel... ... .😄😆😅🤣😂
Master Scott Manley you put me in a very good mood for the day! Thanks a lot 👌👌👌👍
Awesome video! It occurs to me that these could be great for cheap, semi-disposable small craft powered by beamed power using lasers. Without the need for an onboard power source, instead PV panels much smaller than using straight solar, their simplicity really shines. Or, you could have one as a sort of backup on a manned capsule, for if more complicated systems failed.
A laser to heat the gas makes sense to me, can be quite efficient, located outside the chamber and kept nice and cool. Once plasma is formed it becomes opaque to light therefore absorbing more of the energy.
Ink jet -printers also warmup fluid and spray out. Perhaps ink-jet is the cube satellite thruster in the future.
nice
The legend has posted
The arcjet is like a big contained-arc plasma cutter.
14:04
it sortof even has a turntable
just needs a "DING" for when a burn is complete
I would really like to see your take on fission fragment rockets and afterburning fission fragment rockets
It's all about the clearance behind the blast. :P Go Scotty, go! :)
funny thing about arcjet life most of the electrode erosion is caused by the start process and very little is caused by running, so arcjet life is actually limited by the number of starts you want to do as opposed to the total run time.
Thanks Scott!
Niceeeee! Reference to NileRed 😎🙏🇩🇪
So a TIG welding nozzle as a rocket motor? OK! This does make me wonder if you could do a secondary acceleration ionically, since you're cranking potentially plasma level temps, you've got an ionized gas to work with.
The microwave electro driven rocket sounds like you could gather up space debris and it could turn it into plasma and then into thrust.
Just imagine gathering up that small test reactor that's in a storage orbit for an initial energy source. Then you could have an energy source that could even turn a dusty asteroid into plasma. You can divert its course or use it to travel places. I'm sure it's not very efficient but I can dream.
An interesting theoretical use case for arcjets could be to boost the specific impulse of a nuclear-thermal engine. The idea would be that you send the hydrogen through the core twice (or even more times). After the first run through, at high pressure, and perhaps through a lower-temperature section of the core, it enters a turbine, where it expands and does work. This lower-pressure hydrogen is then routed through the reactor again, heated to the typical 3000 K maximum for a solid core NTE - and then the work it did in the turbine(s) is used to drive a secondary arcjet chamber to heat it to perhaps 4000 K, giving a nice 15% or so boost to Isp, admittedly at the cost of a much more complex and heavier engine.
Integza did a video about a really cool solid rocket fuel that is great for thrusters it is ignited electrically but will only burn as long as the current is applied. Pretty much a solid fueled resistor jet.
I remember reading about vasimir in popular mechanics like 10 years ago. Wow.
I never thought of using a storage heater to power a rocket, but I'd also not thought of running a rocket on laughing gas.
What about using freakin lasers to heat the fuel up? You could use directionality to determine chamber pressure. And with a sufficiently advanced system you could make sure every photon is hitting a gas particle.
Great video, Scott...👍
This is so cool! If you can get nuclear thermal rocket performance with these imagine scaling one of these elector thermal thrusters up and using a nuclear reactor to power it. I wonder if it would have enough thrust to get to orbit and I wonder if you can use the atmosphere as the propellant gas at lower altitudes
Thank you,Scott!
"And that, doctor, is how the lightbulb got stuck up there... I was trying to fly!"
I'd love to hear more about VASIMIR, assuming it ever actually flies. Thanks.
6:15 so casually name drops NileRed👌
1 eV is 11606 K. The main issue is that you need to ionize the propellant first. If you take a potassium or cesium ion and accelerated with 100 volts it's exhaust temperature is 1.16 million Kelvin.
Great info, thanks Scott! 🤗
Yes. Please do a video on VASIMR.
While I was TIG-welding in school, I did have the idea of adapting it to a rocket engine working basically as a Arcjet, and then immediately stopped that train of thought because it was a obvious idea and the fact that I'd never read about any of them would imply there's reasons to not do it.
Good to know now WHY its not common at least.
Got a vision now of an elderly astronaut standing in his garden, looking up at a fast-moving "star" in the night sky, with his hand on his grandson's shoulder, saying, "See that son? That's the space station. I kept that in orbit for twenty years with my farts, so the next time your mum complains about them, you just remember that..."
So Scott what about Robert Heinlein's torch ship drives? Are we almost there yet with fusion tech?😎
hmm