AngelLestat

You are wrong.. this is not a hovercraft or other kind of ground effect. At first it will fly at certain height due software limitations, but there are no physsics rules that will keep it on the ground. This thing will have a thrust of 3000 N with just a weight of 100 kg. So if you have 2 passengers which combined weight is 120 kg, you still have 800 N extra of force.

Why you need 1 gw? some vasimr designs goes from 100kw to 50 mw. If you dont need to carry humans, 100kw is enoght. Furthermore nuclear space reactors does not need to be heavy, you dont need the concrete or heavy shielding, you can put the crew very far. The mass of the reactor+heat engine is just a 5% or 15% the radiator mass. A reactor for 100 mw might weight 300kg. There are ship designs already made by nasa with details of each component. That give us an idea. But if you expand the exhaust out, then you lost the critical co2, or you will need to compress it again. About this new method, not sure if that increment in efficiency is keeping the radiation area or not. electric motors are the things with lower waste heat, we are talking of 93% efficiency. The real bottlenecks with nuclear vasimr propulsion, is the core temperature and the radiator temperature. That is what set the efficiency of the whole system. But the weight of the cooling system it depends the amount of heat you need to radiate, but you will lost just 7% of the energy generated, that is nothing compared with the heat engine, which you might lost the 50% or 70% of the energy. You dont gain nothing doing that in space. what are the benefics? Of course, more steps and you add more radiators and mass. I guess other metals are better due the heat capacity. About your superconductors will use a different radiator, if all radiators are on the same plane, then they dont transmit heat between. That has not sense, first nasa is interested in vasimr. Second, if nasa choice to use radiators from 1950 for the space station, is their choice, but it does not mean that we can not include a liquid radiation which is nothing from other world. Just some holes and one collector. You dont need gigawatts as I already mention. Also space PV reach 45% of efficiency. ANd I also mention this option for travels to moon, venus or near asteroids. What they did is an accurate software to model the movement of doplets not matter the circumstance, they will be able to make the corrections needed to collected. So that detail of liquid radiators is not longer a problem. ---------------------------------------------------------------- The real benefic of a nuclear ship vasimr, is that once you have it, you can do any mission you want to any place. You want to go mars... you can and it will be very cheap, go and back, then you want to go to jupiter and drill europa ice.. you can do it, fast and cheap.. The same for any location you will need. Is your cargo ship multipurpose. So the most important is to achieve a core temperature very high, maybe with magnetic confinement and fission melted materials mix and carbon base walls, it will be possible to have a reactor temperature of 2000k, then it will be possible to reduce the radiator temperature to 1000 or 1200 k, which give us 50% efficiency in the heat engine.

If we manage to do reactors of more than 1 gigawatt in earth, why we can not do a reactor from 10 to 100 megawatts in space? About radiators, just 1 week ago they found a way to manage and control a fluid dopplet radiator: https://mipt.ru/en/news/cooling_201508 By the way, not sure why they choose "X" setup for radiators instead line "l", the X setup absorb radiation from other radiatiors, and sun. You have also this project that is trying to find the best way to solve all problems related to: Megawatt Highly Efficient Technologies for Space Power and Propulsion Systems for Long-duration Exploration Missions http://cordis.europa.eu/result/rcn/161150_en.html --------------------------- I told you that you can not compare house rooftop with nuclear plants, if you want to compare do it with solar farms vs nuclear plant "global", not just picking locations, I dont know the real numbers for solar, I just knew that the data for wind was total false, and if they was so unprofessional to manage wind data and nuclear data, then is not hard to imagine is the same for the rest of the study. Remember that this original publication was removed due hard and proven criticism.

Yeah it should be allow it, but the difference with the vehicles you show, is that all of them can land if they have an engine problem. Not sure if you will be able to do auto-rotation with this "bike" her blades are not very long, also if you do auto-rotation you will fall upside down due your body weight. But well, I guess a simple parachute may be enoght to solve those problems About manoeuvrability, any quadrotor has excelent handling, but yeah, you may have some crash, after all there is not fun without that possibility.

Because pure antimmatter annihilation only add good thrust at higher speeds when the drag is a lot higher? About the ion + antimatter as energy source.. mmm I dont understand how.. I can imagine if the matter is close to the funnel center then you dont need to waste a lot of energy to redirect the space dust, but if its at few km away from the ship, not sure how you can restore the deltav lost accelerating that particle with an ion engine. At least that is my assumption, you need a really big scoop at those speeds dont you? Or flying through a planetary nebula. The good news that maybe you dont need a radiator because you will use the same space dust as colling.

I think that I am not qualify to discuss in deep the vasimr mechanism and physsics involve, not sure how you relate this with EM drive.. One has totally sense, the other not. If it needs superconductors to improve its efficiency, then I dont see any problem with that, you will need an extra radiator for that, it may worth it or not. Missions to venus (manned or not) are cheaper and easier. You get all your power from sunlight, why that would be bad?The same solar panels can be your radiators.. the amount of power you need to radiate by unit of area is low. In any case you can use a stirling engine with extra radiators to increase your efficiency. Or you can make a full thermal collector instead PV if you manage to concentrate solar light using very thin reflective layers. But PV already reach 45% efficiency so not sure if it worth it. Also as I said, a solar system is a lot cheaper than nuclear, but to go mars or beyond, a nuclear ship has a lot of sense.. but you need to talk about 300 to 400 tons with many safety measures, it might cost more than the ISS. 100 days might be a logical goal, you dont need huge radiators with powerful reactors and big thermal engines. PD: I send you the answer by PM explaning why the source of nuclear vs wind "safest energy source" was trash.

Lol, that is not a real source.. a source is a paper or scientist publication. That site is just a collection of rocket data from internet or novels. Many used for Role play games. I found a lot of errors in many sections in that site before.

Ok, now I understand why the mass ratio of the atomic rockets site is so big, they assumed for a fix wasteheat of 250 mw. And I guess they showed that way, because that site serve as source for space role games. But that is not the best way to represent radiators values.. The best way is kw/kg, in this way, not matter how much heat you need to radiate, you can calculate depending the tech of choice, how much mass you are adding. This site support my view to maximize the core temperature: "There is a conflicting requirement to both maximise thermal efficiency and maximise the temperature at which heat is rejected. Need to maximise the reactor outlet temperature." http://www.nnl.co.uk/media/1921/nnl-tech-conference-15-fcs-zara-hodgson.pdf Here there is a good site that explain how to make all calculations needed for a radiator. http://www.icarusinterstellar.org/starship-radiators/ For a Nuclear-radiator-vasimr setup, we might be talking about 2 kw/kg. For solar-vasimr setup, we might be talking about 4kw/kg at distances equal or lower than 1au, the benefic that is a lot cheaper and easy to make, it also seems more usefull for low payloads and travels to venus. Advances in Graphene, cnt and optics can improve both setups Nuclear-Solar by a considerable margin. It will be nice if they can build a reusable nuclear-vasimr ship to realize all missions beyond earth, but it will take time.. We should focus on Venus first.

I read the robert zubrin paper on magnetic sails, I dont remember nothing of that mentioned.. But I ask for the source.. what? now I need to look it my self? XD

You have a source claming that? I guess there is this idea that if you have a funnel you are not changing the deltaV of the particles... that is a lie. At low speed might have more chances to succeed, but I guess your funnel should be so big, that the mass added would total neglect the deltaV added for that proppelent.

One time I ask to a scientist if the bussard ranjet would be at least usufull in case you carry only anti-hydrogen, so you need only collect the hydrogen from space (reducing your proppellant mass by half), and not even in that case was usefull to accelerate. So I imagine than it will be even less usefull in the fusion case. No matter how you collect the matter, you are produccing a huge deltav change in each of those particles that you need to restore, the same particle mass as energy is not enoght I guess. About the speed needed to brake.. faster you go, more efficient it is.

Ah, but this happen at 6kelvin :S Graphene already has very good conductive properties, but if we want superconductivity, there are many other possibilities in materials.

A bussard ramjet is only usefull as brake, because the drag you get is higher than the acceleration. But the system will add so much mass, that it would be more usefull to have a magsail for the job.

>_<! still with the pumps? Electrical engines = 90% to 95% efficiency, of course the penalty comes with the batteries. Turbo Pumps = 50% efficiency. Here´s a paper that compare turbo pumps, electrical pumps or just with pressurized gas. Only the first 34 pages. http://www.aacademica.com/hernan.emilio.tacca/9.pdf

What´s everybody talking about? This topic is about Vasimr! Not sure why turbo pumps or electrical pumps are mentioned. Rockets ISP is lower than 450s, Nuclear rocket ISP is lower than 1000s, but that is nothing compared the isp you might have with vasimr, of course there are some cons, but from the top of my head I can said for sure, if we are talking of just 1 trip to mars without worrying at the trip time.. then yes.. lets use rockets. But if the goal is to make a ship capable of interplanetary travel that can be reusable with short trip times, then vasimr seems to be the way to go.

There is not need to search for constants and do the math when we have web sites that do it for us. http://www.endmemo.com/physics/radenergy.php https://www.easycalculation.com/physics/thermodynamics/carnot-cycle-efficiency.php The point is that we need to maximize reactor temperature, I guess 1500c may be our top, or maybe there is different technologies to achieve high temperatures but we are not sure of the weight penalties that might have. http://large.stanford.edu/courses/2013/ph241/kallman1/ The reactor power is the last thing we need to calculate, how much payload we need to carry to mars?

The drone was created to serve for low scale testing purposes, but they sell it to fund the real bike. About the noice, yeah, it will be a problem, but I was not saying that it has future as normal transport remplacement. No, just as recreative purpose, like ATVs or jetskis, etc. I am not sure what kind of design it would need to be used close to public, someone can put the hand by accident on the blades. It would use a normal fuel engine, not sure how they plain to control the thrust. Yeah, its dry weight is 105 kg, 254lb= 115kg Here some extra details of the first model of 2 engines, the second model will use a quadrotor as the one we see in the low scale version. --------------------------------------------------------- SPECIFICATIONS THE SPECIFICATIONS BELOW ARE FOR THE ‘OLD’ BI-COPTER HOVERBIKE. We will disclose the specifications for the new quad-based Hoverbike in the coming weeks. Engine Type Flat twin 4-stroke, one camshaft and 4-valves per cylinder, central balancer shaft Engine Displacement 1170cc Nominal Output @7500rpm 80KW Cooling Aircooled Ignition Electronic Fuel System Electronic intake pipe injection Fuel tank capacity without secondary tanks: 30L with secondary tanks: 60L Fuel Burn 0.5L/min / 30L/hr Fuel Type Regular Unleaded Drive-shafts Custom Carbon fiber Gearbox Custom 1.5:1 reduction Propellers 2 x Oak with carbon fiber leading edge Airframe Carbon fiber with Kevlar reinforcement and foam core Width: 1.3m Length: 3m Height: 0.55m Dry Weight 105kg Maximum takeoff weight >270kg Total Thrust >295kg Range estimated 148km on primary tank Airspeed Vne (untested) Altitude Static Hover >9,800ft (estimated)

Peadar? You look to my numbers? ---------------------------------------------- Hey, everyone, if we wanna know if a vasimir ship to mars really worth it, we need to imagine the best design, gather some estimations for what could be the lightest and high temperature reactor, what thermal cycle we use as engine, what kind of radiator and its area.. the amount of acceleration and proppelent. It does not seems so hard.. (in case we look for an estimation)

I really see future in this This brings back star wars memories. It seems at beginig it will be just to hover.. But I guess it can be implemented to really fly with good safe concerns, for example if the "bike" can stay in the air with 3 engines and carrying a parachute in your back so it can safe both (you and the bike). Because it would not be safe if you left the bike fall. Of course its range should be less than 150km What everybody thinks? it has future?

That is true because you should maximize ISP in relation with your time trip goal, also if you are not using the reactor power, you are carrying death mass.

No, is not that. First I thought that maybe it depends on the amount of waste heat you need to radiate by m2, because if you have a very thin graphene layer, meanwhile it has the same area, it will radiate the same amout than a very thick block of iron or ceramic. But that is true for radiation, but you need also conductive transfer to reach all the area, there is where the thick may enter in play.. But I am not sure you need so much mass when you are talking about just 300 kw/m2. I highly doubt it. Also I understand the basis of almost each design mentioned in that page and still, not sure how it has so heavy system radiator density. Is not the first time I visit that page, I found some errors before in ISP for some designs and when it talks about Solar or Beamed sails. That is why I look those numbers with doubt. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130001608.pdf Heh, because he only wanted to calculate the optimal difference in temperature between the source and the radiator, "to minimize radiator area", which is true, it needs to be 75%. But it does not mention in the final equation the source temperature, only the difference. Take a look to these examples: Reactor Power 100 Mw 75% ratio --> 1000-750k / 25% efficiency / 34kw/m2 / 2200m2 75% ratio --> 2000-1500 / 25% efficiency / 544kw/m2 / 137m2 (higher temperature in the core maximizes radiator efficiency) 50% ratio --> 2000-1000 / 50% efficiency / 106kw/m2 / 471m2 (4x radiator area but generates 2x power so we can reduce the reactor power and weight) So to know the best temperature ratio from the whole system we also need to know the reactor mass and the heat engine mass depending its power. Is like I said, if the radiator mass is low comparable to the reactor and engine mass, then we should maximize efficiency instead minimize radiator area.

Not sure why the mass density for all radiators is so high... it said 24kg/m2 or similar for other kinds of radiators. Meanwhile Nasa is looking for 2 to 4 kg/m2 which is totally coherent, and there is some papers that achieve 2.5 just using carbon fibers.. nothing special. Think about it, why it needs 24kg/m2??? That weights more than 1 m2 of heavy mosaic, meanwhile a very thin carbon layer can do the same work. The key here is to maximize the core temperature in the reactor, I guess 1500 celcius is possible.

The explanation of the filter that your blog talk about, it may be also explained in the same blog: http://waitbutwhy.com/2015/01/artificial-intelligence-revolution-1.html Or the same thing we are discussing here: http://forum.kerbalspaceprogram.com/threads/132357-Everything-wrong-with-our-predictions-%28The-Singularity-is-coming%29 We are reaching a step in our tech progress that might be equal common for all species, the singularity. This effect may be comparable with supernovas type 1a, no matter in what part of the universe they occur, they all explode with the same intensity, in the singularity case, we (or the AI) reach all the possible knowledge that can be know in a very short time, after that we (or the AI) may find a hiden true which dictates a common end (no matter what kind of "being" you were before). Or maybe, if there is not more goals, we (or the AI) lose our purpose. Maybe there is not life without purpose, and maybe; that is the meaning of life.

Peadar, that highly depend on the radiatior mass efficiency. What kind of material and system are you using for your hypothetic radiator? There are new materials and techniques that can increase that by a lot.

As I said.. this is not the place to have this discussion, we already had this discussion in 3 different threads. If you want.. make a new thread and I will prove you there how that stadistic source is full of trash. You can have a combined cycle to produce extra power from the waste heat (but it does not reduce your radiatior area or mass, in fact is increased) Not sure what it would be the ultimate design solution for a Vasimir-nuclear ship (in case vasimir works as is expected). If you plan to have many trips to mars go and back, it might have sense. Maybe engines on front with a very long "cable" that might act also as radiator with a liquid heat carrier might work. After acceleration the cable can be used as artificial gravity between the reactor-engine and the crew cabin. A magnetic field in the crew cabin may divert the radioactive particles from the exhaust.