RGClark - 12/1/2008 11:05 AM The problem is the high amount of power required. However highelectrical power has been delivered up to hundreds of kilometers onEarth over power lines. Then this could be used to deliver therequired electrical power to the thrusters from the ground.
RGClark - 12/1/2008 4:28 PM You could have a cable lying on theground and a short length of cable extending from the craft to thecable on the ground, say 10 to 100 meters long. Keep in mind, just asfor the magnetic launch proposal, the main thing is getting thathorizontal velocity component required for orbit. To get to thealtitude for LEO is just a small proportion of extra velocity andenergy of that required for orbital velocity.
khallow wrote: "...For example, if somehow you could attack 500kV lines to a rocket, that would still need 8 amps of current to generate the equivalent power of an Atlas V first stage (which happens to be around 4 million newtons)...'
You are mixing your units here. Dimensions for Power is defined to be energy per unit time--the rate at which work is done, and energy can be thought of in terms of a force acting through a displacement. Newtons have dimensions of Force...
From:
http://www.astronautix.com/engines/rd180.htm
An Atlas V, using an RD-180 rocket engine generates a sea level thrust of about:
4,152 kN (933,333 lbf) with a sea-level Isp=338 sec which corresponds to a sea-level exhaust velocity of about: 338 s * 9.80665 m/s^2 = 3315 m/s.
We can estimate the mechanical power of the 'exhaust jet' by finding the kinetic power of the mass throughput of the RD-180:
The kinetic energy of a freely moving mass can be found from:
K=1/2*m*v^2, and differentiating with respect to time holding v constant gives:
P=1/2*mdot*v^2 where P is the kinetic power of a mass stream, and mdot is the mass flow rate.
The propellant consumption rate for an RD-180 can be estimated from dividing the thrust in newtons with the exhaust speed in meters per second:
mdot = 4.152 x 10^6 N / (3315 m/s)
= 1253 kg/s
Thus the kinetic power of the exhaust gasses exiting the engine at sea-level is about:
P=1/2*1253 kg/s * (3315 m/s)^2
= 6890 MW.
Assuming of course that the energy conversion from electrical supply to delivered thrust is 100%, and you have a light-weight, beefy 500KV line supplying power, the current must be atleast:
I=P/V
I=6890 MW / 500 KV
= 13800 Amps.
So it would seem that either a bundle of such cables must be present, or the voltage must be higher, or maybe a superconductor would have to be used...
Either way, I would imagine that the utilities would find delivering nearly 7GW to a single customer challenging, let alone delivering it to something as small as an Atlas V--let alone have that Atlas V actually flying at the same time!
TyMoore - 16/1/2008 2:05 PMEither way, I would imagine that the utilities would find delivering nearly 7GW to a single customer challenging, let alone delivering it to something as small as an Atlas V--let alone have that Atlas V actually flying at the same time!
Lampyridae - 16/1/2008 8:55 PMSo, let's make the cables stationary somehow, hanging from an aerostat or ducted fans or whatever. Now we only need 6.4MN of thrust (our payload, rocket and fuel is only 1 tonne for ease of calculation). How much power must go through those cables? Answer: lots. We match our exhaust velocity (eV) to our orbital velocity; let's call it 10kps eV to keep it simple. Increasing eV beyond your mission deltaV is a bit pointless.So:6.4MN x 10 000 = 64 GW.About the power requirements of a small country. Still, now it's doable.
RGClark - 17/1/2008 1:40 AMKhallow, we don't have lasers at multi megawatt to gigawatt power currently. Also to focus the lasers at hundred kilometer distances would require unacceptably large mirrors.
RGClark - 17/1/2008 6:37 PMQuoteLampyridae - 16/1/2008 11:55 PMSo, let's make the cables stationary somehow, hanging from an aerostat or ducted fans or whatever. Now we only need 6.4MN of thrust (our payload, rocket and fuel is only 1 tonne for ease of calculation). How much power must go through those cables? Answer: lots. We match our exhaust velocity (eV) to our orbital velocity; let's call it 10kps eV to keep it simple. Increasing eV beyond your mission deltaV is a bit pointless.So:6.4MN x 10 000 = 64 GW.About the power requirements of a small country. Still, now it's doable. You wouldn't have to be restricted to a distance over which you are accelerating of 10 km, necessitating that large acceleration of 640 g's. Overhead electric power lines a few centimeters wide routinely run over hundred kilometer distances. If you allowed the distance to be a few hundred kilometers, then the acceleration could be in the 10 g's range. This would also mean you could transport larger mass for the same power. Then for a 1000 kg total mass, the thrust would only have to be 100,000 N.
Lampyridae - 16/1/2008 11:55 PMSo, let's make the cables stationary somehow, hanging from an aerostat or ducted fans or whatever. Now we only need 6.4MN of thrust (our payload, rocket and fuel is only 1 tonne for ease of calculation). How much power must go through those cables? Answer: lots. We match our exhaust velocity (eV) to our orbital velocity; let's call it 10kps eV to keep it simple. Increasing eV beyond your mission deltaV is a bit pointless.So:6.4MN x 10 000 = 64 GW.About the power requirements of a small country. Still, now it's doable.
BTW, the MPD thrusters I've seen always give these high exhaust velocities of 60,000 to 100,000 m/s, desirable for planned uses of carrying several tons on manned planetary missions. However, power scales as the square of the exhaust velocity. I don't know if they've been tested or it they can work at low exhaust velocities. This would require much larger fuel loads at low exhaust speeds, if you were carrying fuel. However, would they work with just the surrounding air? Then you could use low exhaust speed to minimize power and get high thrust by having large volume of air being accelerated. Bob Clark
RGClark - 18/1/2008 6:04 PMMagnetoplasmadynamic Thrusters."Testing for these thrusters has demonstrated exhaust velocities of100,000 meters per second (over 200,000 mph) and thrust levels of 100Newtons (22.5 pounds) at power levels of 1 megawatt.{snip} I estimate the weight of these thrusters as less than 100 kg. You can get the engine thrust-to-weight ratio be high by giving the same thruster more power.
RGClark - 18/1/2008 1:19 PM Then a large helium balloon could keep the longer cable aloft if thecable were say 1 mm wide. But you might need a cable 1 cm wide orlarger to carry sufficient current to power the craft. Possiblyseveral helium balloons along its length would work to keep it aloftin this case.
RGClark - 21/1/2008 1:05 AMIt is known that if subjects are immersed in water they can survive higher accelerations. On this page at the bottom is given a table of durations for accelerations while water immersed:Adventuring hazards.http://hiddenway.tripod.com/hero/hazards.html At 28 g's it's given as .5 min, 30 seconds. At this acceleration you could achieve 280*30 =8,400 m/s in 30 seconds. The distance it would take to get to 8,000 m/s would be 8,000^2/(2*280) = 114,285 m =114 km.
RGClark - 3/2/2008 11:20 AMWhile doing a web search I found a report on creating inflatable vacuum chambers, where the walls are filled with pressurized gas for strength. Such chambers could even be buoyant if the walls were filled with a lighter than air gas such as helium.This then could be used to extend a vacuum travel path from the ground all the way to high altitude for orbital rocket launch.Stability Analysis of an Inflatable Vacuum Chamber.http://arxiv.org/abs/physics/0610222v4Bob Clark
khallow - 4/2/2008 4:31 AMOr you could use a better way of delivering power to the launch vehicle that doesnt't require a physical connection to the vehicle.What are the advantages supposed to be? I really don't understand why people are considering this. At least with things like beamed power or a space elevator, it doesn't take that much extension of current technology and materials to make the idea possible. But we have no idea how to make cables that can withstand for long enough the turbulence of an atmospheric launch, the force from the exhaust of the rocket in vacuum, electromagnetic forces interacting on the cables from each other, and even tidal forces from nearby moons and planets. Even if you get around the stability problem, you still are limited by both how much power the cable can carry since you have to worry about heating and arcing. And we ignore how you can get an electrical connection when you're moving at several kilometers per second.I have to side with Jim here. The physics doesn't appear to support this sort of thing. Nor does it seem to have a notable advantage over other methods of accelerating in space or atmosphere.
kevin-rf - 4/2/2008 6:54 AMQuoteRGClark - 3/2/2008 11:20 AMWhile doing a web search I found a report on creating inflatable vacuum chambers, where the walls are filled with pressurized gas for strength. Such chambers could even be buoyant if the walls were filled with a lighter than air gas such as helium.This then could be used to extend a vacuum travel path from the ground all the way to high altitude for orbital rocket launch.Stability Analysis of an Inflatable Vacuum Chamber.http://arxiv.org/abs/physics/0610222v4Bob ClarkFor the chamber to be lighter than air the enclosed volume of vacuum just has to be large enough to offset weight of the Inflatable Chamber. You do not need helium, air will do. In english the mass of the volume enclosed has to be less than the mass of an equiv. volume of air. Google archimedes, just don't share the pic's of you running through the street when done It has always been a dream (pipe dream) to make a lighter than air vacuum chamber. Thanks for an idea that may work. Now I can tell the voices in my head I am not all that crazy :laugh:
RGClark - 4/2/2008 3:41 PM Keep in mind that the hundred kilometer long fixed electrical cable carrying hundreds of megawatts is something that already exists now and has existed for decades.
RGClark - 4/2/2008 4:20 PM Fundamental to the proposal is that the hundred kilometer long power cable is not being carried by the rocket. It is fixed in position supported at altitude by either balloons or its own thrusters. The rocket only has to carry a short conducting tether perhaps a few hundred meters long to transmit the electrical power from the power line to the rocket. Bob Clark
Jim - 5/2/2008 6:44 AM3 things still undoable1. the interface between the tether and the cable. Won't be able to maintain it at 1000's of mph due forces and heat2. suspending the cable above 30km. not with thrusters, they need propellant mass. How are they going to be refueled?3. LV's move a lot more than a few hundred meters from the planned trajectorythis cable is going to strung out for 1000's of miles from the launch site? Going straight up won't work, the vehicle has to be going horizontal at orbital insertion
Lampyridae - 5/2/2008 12:24 AM1. Plasma armatures work well enough for railgun projectiles, basically just arcing across the gap.
Lampyridae - 5/2/2008 6:24 AMQuoteJim - 5/2/2008 6:44 AMthis cable is going to strung out for 1000's of miles from the launch site? Going straight up won't work, the vehicle has to be going horizontal at orbital insertion
Jim - 5/2/2008 6:44 AMthis cable is going to strung out for 1000's of miles from the launch site? Going straight up won't work, the vehicle has to be going horizontal at orbital insertion
1. Plasma armatures work well enough for railgun projectiles, basically just arcing across the gap.
pippin - 5/2/2008 6:34 PMQuoteLampyridae - 5/2/2008 6:24 AMQuoteJim - 5/2/2008 6:44 AMthis cable is going to strung out for 1000's of miles from the launch site? Going straight up won't work, the vehicle has to be going horizontal at orbital insertionIf I got my gravity right, it will be almost vertical at the top end because it's hanging through... Doesn't fit well
Quote1. Plasma armatures work well enough for railgun projectiles, basically just arcing across the gap.They don't transfer electrical power to the projectile through arcs, the just induce a current within the projectile. Arcs are accidental and cause losses. You could theoretically do inductive coupling for power transfer to your cable and you could even use inductive repelling force to keep your power line away from the collector ("pantograph") but to get the power up there then you would need a closed loop, high frequency AC power transmission with what probably has to be a superconducting cable.Hmmm... Quite a bit of onobtainium in use here.
Jim - 5/2/2008 2:37 PMQuoteLampyridae - 5/2/2008 12:24 AM1. Plasma armatures work well enough for railgun projectiles, basically just arcing across the gap.There still is something that holds it in place
Lampyridae - 6/2/2008 1:24 AMIt might do if the projectile was launched at escape or near-escape velocities. Or maybe straight up into geosynch... although that notion vaguely offends me.
RGClark - 7/2/2008 4:26 PM1. This idea might also work for transmitting the electrical power from the long power line to the rocket's conducting tether in my proposal without the extreme friction at the highest Mach speeds. The tether would have slippers at its end sliding along the power cable. At the very highest speeds the air between the slippers would likely become ionized and therefore highly conducting. Then even though the slippers would not be touching the power line, the thin layer of ionized air would still conduct the electrical power to the tether. 2. If the inflatable vacuum chamber can indeed be made to work (it has not yet been successfully demonstrated in experiments), then it might be used around the Holloman track rather than the helium shroud. This might allow orbital velocity to be reached with just the multi-stage rockets now being used.3 This though would remove the advantage that exists now with the slippers riding on a thin layer of gas. Perhaps a very low density residual gas would be sufficient to raise the slippers above the rails. As it is now you have to have the helium at the same pressure as the surrounding air since the thin tent would not be strong enough to hold back the outside pressure without the equalizing pressure of the helium.
sandrot - 8/2/2008 1:27 PMAnd if the rocket blows up at liftoff the whole structure will come down as the balloons will be punctured.
RGClark - 8/2/2008 8:09 PMThis would also eliminate the problem of it pointing straight up at the end if you had several balloons along its length. You could instead have it be relatively straight near its end.
RGClark - 8/2/2008 2:09 PM True if there were only a single helium balloon supporting it at the one end. However, you could have several different ones supporting it along its length, say every 5 km if you wanted. This would also eliminate the problem of it pointing straight up at the end if you had several balloons along its length. You could instead have it be relatively straight near its end.
RGClark - 8/2/2008 7:34 PM 1. The bend of the catenary depends on how far apart the supports are.2. Also, if the cable was made buoyant itself by making it hollow filled with helium then you could make it be straight.
RGClark - 8/2/2008 8:02 PM In correspondence with the developer of this idea, a physicist at Florida State University, I understand the impetus of this was specifically to produce arbitrarily long lightweight vacuum chambers to serve, for example, as long, vacuum travel paths for rockets.
A_M_Swallow - 10/2/2008 1:14 PMTo get to orbit build a 5 mile maglev up the side of a mountain, reaching 800 km/h and then use an ordinary stage 2 rocket.
Jim - 10/2/2008 6:19 PMQuoteA_M_Swallow - 10/2/2008 1:14 PMTo get to orbit build a 5 mile maglev up the side of a mountain, reaching 800 km/h and then use an ordinary stage 2 rocket. Another flawed idea. How many 5 mile mountains how the proper slope and are situated in the proper orientation .
A_M_Swallow - 10/2/2008 12:47 PMWe only need one, preferably in the tropics. If the angle is too steep add electric motors, there are advantages in having a Stage 1 that never leaves the ground.Mount Mauna Kea on Hawaii has a peak 10,200 metres (33,500 ft = 6.3 miles) above the sea.
RGClark - 10/2/2008 6:22 PM You see that when the applied horizontal force is large, the sag at the center is lowered.
The formula for the sag at the center of a beam freely supported at its ends is given here:Deflection.http://www.cda.org.uk/megab2/elecapps/pub22/sec8.htm#Deflection[blah blah I remeber well from my mechanics classes erased]I calculate using 70 gigapascals for the modulus of aluminum, that for a horizontal beam 10 meters long, 10 centimeters vertical width, and 1 millimeter horizontal width, the sag at the center would be 40 centimeters. If that recent announcement about an aluminum composite stronger than carbon fiber at lighter weight is correct and if this strength also applies to its modulus then since carbon fiber has a modulus ten times that of aluminum, the sag should be less than 4 centimeters for this composite for the same dimensions.
Also, if the power cable were to provide its own buoyancy by being microns thin and meters wide filled with helium, then it would be straight because at each point it is providing its own lift rather than only being lifted at the endpoints. Then you wouldn't need the ground tether wires to provide horizontal tension. You would still need them though to keep the lighter than air cable stable against winds.
Note if you used electrically powered thrusters or even propellers to keep the power cable stable against winds then you wouldn't need the ground tethers at all. Remember back on page 3, I suggested using the principal of the hot air balloon to provide buoyancy for the power cable instead of helium? Interestingly such balloons can be run on solar power alone:Solar hot air balloons.http://pagesperso-orange.fr/ballonsolaire/en-index.htm
You could also provide stability against the winds by venting the heated air through nozzles. This would also dispense with the need for ground tethers.
gospacex - 10/2/2008 8:29 PMQuoteA_M_Swallow - 10/2/2008 12:47 PMWe only need one, preferably in the tropics. If the angle is too steep add electric motors, there are advantages in having a Stage 1 that never leaves the ground.Mount Mauna Kea on Hawaii has a peak 10,200 metres (33,500 ft = 6.3 miles) above the sea.?! The highest spot on Earth is 8848 meters only, and it is in Himalaya. You meant 10 km for the (submerged) base?
RGClark - 11/2/2008 1:57 PMQuoteA_M_Swallow - 10/2/2008 4:32 PM...When I copied the hight I did not realise that someone would measure a mountain from underwater. That is why I added the p.s. Another point to consider is that it is really the trajectory length that has to be 5 km, not the vertical height.
A_M_Swallow - 10/2/2008 4:32 PM...When I copied the hight I did not realise that someone would measure a mountain from underwater. That is why I added the p.s.
RGClark - 11/2/2008 5:38 PM 1. Thanks for such a thoughtful response. I see no problem with putting the helium balloons every 10 meters or every 1 meter. That just means you could use much smaller balloons. You won't break the world market in small helium balloons by using several thousand of them. If it sufficed for the required current capacity to make the cable have a 1 sq. mm cross-sectional area (while keeping the strong rectangular shape) then just a couple of those little party helium balloons sold at dollar stores would be sufficient to lift a 10 meter long segment. See this page:2. For the weight of the power cable itself, a cable of cross-section of 1 sq. cm and 10 meters long made of aluminum weighs about 2.7 kilos. So one 100 km long would be 27,000 kilos. It would not be thousands of metric tons. And if a 1 sq. mm cable sufficed it would be 1/100th this weight or only 270 kilos. Note also such lengths would be necessary only for manned craft that needed low accelerations . For unmanned craft that could be hardened to withstand hundreds to thousands of g's the length would be only in the 10's of kilometers range, or less.
pippin - 8/2/2008 11:22 PMQuoteLampyridae - 6/2/2008 1:24 AMIt might do if the projectile was launched at escape or near-escape velocities. Or maybe straight up into geosynch... although that notion vaguely offends me.With good reason: it's wrong. Going straight up into GSO wouldn't work since you don't have the necessary (horizontal) speed. The angular rate is the same for earth' surface and a satellite in GSO but not the velocity!The theoretical construct of an space elevator works because it would actually accelerate it's payload during the way up!
TrueBlueWitt - 9/2/2008 2:35 AMInteresting if flawed ideas.. As long as people are throwing stuff out there, this is my personal pet launch setup.Build a lightweight launch platform that can be lifted by balloons(at the end of long cantilevered trusses off the corners).. possilby augmented by a number of highly efficient 100,000+ lb thrust Commercial Aircraft Turbofans(or take the VTOL system out of the F35?)...
Take the platform up above 40,000-50,000ft and launch from there. Then you could vacuum optimize your first stage nozzles to get higher ISP. Also greatly reduces issues with maxQ. Take the thing out over water for launch.. would help reduce size/mass requirements of launch abort system on manned rockets as well. Of course not as much fun to go watch a rocket launch.Crazy? I'd be interested to hear everyone's thoughts.
RGClark - 12/2/2008 7:38 AMFor the weight of the power cable itself, a cable of cross-section of 1 sq. cm and 10 meters long made of aluminum weighs about 2.7 kilos. So one 100 km long would be 27,000 kilos. It would not be thousands of metric tons. And if a 1 sq. mm cable sufficed it would be 1/100th this weight or only 270 kilos. Note also such lengths would be necessary only for manned craft that needed low accelerations . For unmanned craft that could be hardened to withstand hundreds to thousands of g's the length would be only in the 10's of kilometers range, or less.To give a real world example of how light long distance power lines can be, the Ekibastuz-Kokshetau power line runs 432 km carrying 1 megavolts and only weighs 50,000 kilos.
Look, you are making loads and loads of basic assumptions, and you know what assumptions are the mother of.
1 megavolt is NOT the same thing as 1 megawatt, and that is not quite the same thing as 1 megaVA. I could build a 483km line of hair-thin copper wire that carried 1 megavolt but I would only get enough current out of it to turn on a lightbulb.
Let me give you some good advice from the point of a non-expert and an armchair engineer that will make your time on this forum much more productive and enjoyable. Although I am not an engineer, I have read engineering books, over and above my usual studies. Sometimes I actually am qualified to offer a good opinion, whenever the discussion wanders into territory that I know. If you look at my posts, you'll notice that I've largely commented on stuff relating to aerodynamics. That's 'cause it's what I know, because I studied a bit of related stuff at university, but also because I got myself a nice intro textbook on Aeronautical Engineering and read it. Also, and maybe more importantly, I have actually gotten my hands dirty wrestling with diesel engines and electrical cables. I have stripped threads off of bolts, electrocuted myself and blown things up. Not nearly as much as the real engineers and techs here, but the point is that you get an intuitive feel for the strengths of materials and the viability of options. Earlier on, I mentioned "going straight into GEO" from the ground up, but something bugged me about it and pippin told me why I was wrong. I then thought about L1, and again realised that it's a dumb idea (going on pippin's logic).
Now, you've had your cable proposal savaged by several aeronautical engineers (Jim is actually giving you a detailed analysis of why it won't work instead of half a sentence, you should be honoured), but the idea is just full of holes. You've probably learned a bit about cables (and me too), but the idea is just not worth sticking to!
If I were you, I would go and investigate the properties of cables. What are they good for? What can they be made to do? What does DC current do? I've thought of a couple of ideas based on the initial premise of a current-carrying cable, because I believe it is an interesting concept and worth exploring. I'll do a bit more work on them and then bring them to this thread to be torn apart by the experts.
RGClark - 11/2/2008 6:57 PM BTW, I don't understand why such a low speed of 800 km/hr would be beneficial. The Saturn V first stage for instance took the Apollo missions to 10,000 km/hr 2,700 m/s before cutoff. Bob Clark
QuoteTo give a real world example of how light long distance power lines can be, the Ekibastuz-Kokshetau power line runs 432 km carrying 1 megavolts and only weighs 50,000 kilos. Look, you are making loads and loads of basic assumptions, and you know what assumptions are the mother of.1 megavolt is NOT the same thing as 1 megawatt, and that is not quite the same thing as 1 megaVA. I could build a 483km line of hair-thin copper wire that carried 1 megavolt but I would only get enough current out of it to turn on a lightbulb.
To give a real world example of how light long distance power lines can be, the Ekibastuz-Kokshetau power line runs 432 km carrying 1 megavolts and only weighs 50,000 kilos.
Thanks for all the detailed responses. The feedback is appreciated. I forgot to give the web link for that 1 megavolt powerline:Powerline Ekibastuz-Kokshetau.http://en.wikipedia.org/wiki/Powerline_Ekibastuz-Kokshetau
RGClark - 12/2/2008 10:21 AM So you would need, for example, helium balloons of twice the diameter to lift these than that needed for 1 cm wide cables.
RGClark - 12/2/2008 1:22 PM For instance instead of many separate small balloons, we could have a single long, hollow helium balloon all along the length of the cable.
RGClark - 12/2/2008 2:33 PM 1.You could have the power cable running along the top of the long balloon. This might make it top heavy though so you might want to have a counterweight hanging down from the balloon as well. If the counterweight was the same weight as the weight of the cable this would increase the weight that had to be supported only by a factor of two. Then the diameter of the long balloon would only have to be larger by a factor of 1.4. 2. You can make the volume of the long balloon at each point along its length correspond to the altitude and air density at that point so that the structure is neutrally buoyant along its length. 3.The cable does not have to go to orbital altitude. The key aspect in getting to orbit is achieving orbital velocity, 7,000 to 8,000 m/s. The energy and velocity needed to get to 100 km or 200 km altitude is small in proportion to that needed for orbital velocity. So once the rocket reached orbital velocity at, say, 30 km altitude you just point it upward and give it a little extra velocity to place it at the desired orbital altitude.4.My background is in pure math, what's yours?Bob Clark
RGClark - 12/2/2008 9:29 PMQuoteDMeader - 12/2/2008 2:49 PMMr. Clark,Actually, he IS a rocket scientist!I'd suggest you let this go. No offense. But after the Columbia accident, to those of us in other technical fields being called a rocket scientist is not regarded as a ringing endorsement.
DMeader - 12/2/2008 2:49 PMMr. Clark,Actually, he IS a rocket scientist!I'd suggest you let this go.
RGClark - 12/2/2008 7:33 PM My background is in pure math, what's yours?
RGClark - 12/2/2008 9:29 PM No offense. But after the Columbia accident, to those of us in other technical fields being called a rocket scientist is not regarded as a ringing endorsement.
pippin - 13/2/2008 6:00 AMAlso no offense, but that fits my notion of somebody who does not have a clue about things, thinks everything is easy and people who don't follow these easy solutions are just morons.I suggest you try out some of my suggestions and report back with your results in another thread (PRACTICAL results, please!)I think this thread has had enough...
RGClark - 13/2/2008 11:56 AMWindmills in the Sky.A bold plan to tap the jet stream and boost our nation's energy supply.By Michael Behar Posted 11.21.2005 at 2:00 am.http://www.popsci.com/scitech/article/2005-11/windmills-sky
RGClark - 21/2/2008 5:24 PMActually it points upwards at an angle which is what you want so that most of velocity component is in the horizontal direction to achieve orbital velocity and a smaller component in the vertical direction to achieve orbital altitude. Bob Clark
pippin - 21/2/2008 11:46 AMQuoteRGClark - 21/2/2008 5:24 PMActually it points upwards at an angle which is what you want so that most of velocity component is in the horizontal direction to achieve orbital velocity and a smaller component in the vertical direction to achieve orbital altitude. Bob ClarkThe "angle" will be close to 90°. All that has been said from the beginning of the thread applies to this. No difference whether it's wind or a turbine that pulls on the balloon.
Jim - 21/2/2008 7:42 PMThe cables goes 57km horizontally and only 8 km vertically. Just the exact opposite of a "standard" trajectory. It spends too much time in the atmosphere
RGClark - 4/3/2008 5:15 PMAccording the U.S. patent office the idea of sending high electrical power along power lines held aloft seveal kilometers in the air is viable. This married with the fact that a rocket running on electrical power from the ground has essentially unlimited power makes reusable rockets easy and cheap. Bob Clark
RGClark - 4/3/2008 2:15 PMAccording the U.S. patent office the idea of sending high electrical power along power lines held aloft seveal kilometers in the air is viable.
hop - 4/3/2008 5:13 PMQuoteRGClark - 4/3/2008 2:15 PMAccording the U.S. patent office the idea of sending high electrical power along power lines held aloft seveal kilometers in the air is viable.The USPTO says no such thing.The issuance of a patent says almost nothing about the possibility, never mind practicality of the invention. In theory, they aren't supposed to issue patents for things that are obviously impossible, but in practice there's plenty of patents on all kinds of fantastic nonsense.Charlatans and quacks have long used patents to lend an air of authenticity to their output, but is based on exploiting the publics misunderstanding.
RGClark - 5/3/2008 12:38 PMQuoteJim - 4/3/2008 8:04 PMQuoteRGClark - 4/3/2008 5:15 PMAccording the U.S. patent office the idea of sending high electrical power along power lines held aloft seveal kilometers in the air is viable. This married with the fact that a rocket running on electrical power from the ground has essentially unlimited power makes reusable rockets easy and cheap. Bob ClarkThat is the major hole. It can't be married. There is no way of getting the power to the rocket. Also several km is not orbital altitude. Why can't you understand this not viable Not only is it viable it is fact easy.You have proven nothing. And you definitely can't say easy. You don't have the engineering or knowledge to say that. You have only strung together unrelated topics. For example,high altitude to minimize air drag and heating is above 60 miles, way above balloonsShort distances? that means inches and not hundred of feet Bob Clark
Jim - 4/3/2008 8:04 PMQuoteRGClark - 4/3/2008 5:15 PMAccording the U.S. patent office the idea of sending high electrical power along power lines held aloft seveal kilometers in the air is viable. This married with the fact that a rocket running on electrical power from the ground has essentially unlimited power makes reusable rockets easy and cheap. Bob ClarkThat is the major hole. It can't be married. There is no way of getting the power to the rocket. Also several km is not orbital altitude. Why can't you understand this not viable
RGClark - 5/3/2008 9:01 AMQuotekhallow - 5/3/2008 3:21 AMFor example, there's probably been a zillion patented perpetual motion or "free energy" machines. Not a one has been shown to work, that is to produce at least as much work as was put in. KHallow, the patent office specifically disallows perpetual motion machines, or any device that appears to put out more energy than it takes in. Bob Clark
khallow - 5/3/2008 3:21 AMFor example, there's probably been a zillion patented perpetual motion or "free energy" machines. Not a one has been shown to work, that is to produce at least as much work as was put in.
RGClark - 5/3/2008 4:36 PMHowever, one of the main criticisms was that supporting high power lines at kilometers high altitude was not feasible. This is in fact being investigated and being funded at preliminary stages for wind power generation.
RGClark - 5/3/2008 3:31 PM1. The conducting rocket tether could be within inches of the power line to still transmit high power from the power line to the rocket. However, there are also methods to transmit high electrical power over hundreds of feet if you wanted to avoid the use of the tether.2. I say implementing the proposal would be easy based on the granted patents and the papers published in peer-reviewed journals on the high altitude power generation. 3. The parts of the proposals having to do with maintaining the power lines at altitude are the easy parts of the proposals.
RGClark - 5/3/2008 8:31 PM The proposals for scramjets, where they are using the surrounding air for combustion, also rely on getting this air up to altitudes in the range of 30km to 50 km. Helium balloons have also been flown up to 50 km altitude; so could be used for supporting the power lines at this altitude. The conducting rocket tether could be within inches of the power line to still transmit high power from the power line to the rocket. However, there are also methods to transmit high electrical power over hundreds of feet if you wanted to avoid the use of the tether.
RGClark - 5/3/2008 9:31 PM I say implementing the proposal would be easy based on the granted patents and the papers published in peer-reviewed journals on the high altitude power generation. Bob Clark
A_M_Swallow - 5/3/2008 2:43 PMR G Clark time for the numbers.How heavy is a 30 km long electrical power tether?How heavy is your vehicle?How much of a force does the accelerating vehicle apply to the cable?How big a balloon is needed to support tether and launch force?
RGClark - 5/3/2008 10:22 PMQuoteJim - 5/3/2008 5:42 PMModerators please lock this thread. The author has no concept of debate and physics for the matter. It is a useless On the contrary, for all the objections raised I have pointed to specific references that show the proposal is feasible. These references are by experts in the field. I certainly don't think they are unaware of the physics involved. Bob Clark
Jim - 5/3/2008 5:42 PMModerators please lock this thread. The author has no concept of debate and physics for the matter. It is a useless
RGClark - 6/3/2008 4:37 AMQuotepippin - 5/3/2008 11:59 PMPatents have no technical value. Patents are for claims management only. Yes, they do. If the invention works, then it tells other people how also to make it. You could of course do the same thing in a research publication. The key fact is they both are peer-reviewed. There sometimes are mistakes made with patents just as there are sometimes mistakes made with peer-reviewed journals. Bob Clark
pippin - 5/3/2008 11:59 PMPatents have no technical value. Patents are for claims management only.
RGClark - 6/3/2008 1:37 AMQuotepippin - 5/3/2008 11:59 PMPatents have no technical value. Patents are for claims management only. Yes, they do. If the invention works, then it tells other people how also to make it. You could of course do the same thing in a research publication. The key fact is they both are peer-reviewed. There sometimes are mistakes made with patents just as there are sometimes mistakes made with peer-reviewed journals.
RGClark - 6/3/2008 6:47 PM I could argue that you yourself are setting up a "straw man". As I said and you are well aware of you don't have to maintain powered flight to orbital altitude. You just attain sufficient velocity to achieve orbit, point it upward
RGClark - 6/3/2008 3:47 PMThis is how all proposed methods for launch that accelerate the satellite at ground level work, such as gun launch, magnetic launch, etc.
RGClark - 6/3/2008 5:29 PM True. As far as I know all such ground level orbital velocity systems, like gun launch for example, are only envisioned for small micro satellites, 10 kg or so, shaped like thin, compact missiles.
But proposed hypersonic scramjets reach their high Mach speeds at altitudes in the range of 30km to 50 km, still within the atmosphere, to support combustion.
RGClark - 6/3/2008 8:38 PMQuoteJim - 6/3/2008 7:47 PMQuoteRGClark - 6/3/2008 6:47 PM I could argue that you yourself are setting up a "straw man". As I said and you are well aware of you don't have to maintain powered flight to orbital altitude. You just attain sufficient velocity to achieve orbit, point it upward That minimum altitude is around 70km, still too high for a cable. It would be too much aeroheating below that. still to high for an anchor. So still not viable.It is not even worth testing. No, the orbital scramjet proposals have to remain in the atmosphere during powered flight since they get their oxygen from the air. They reach their highest Mach speeds at the altitude range of 30 km to 50 km.
Jim - 6/3/2008 7:47 PMQuoteRGClark - 6/3/2008 6:47 PM I could argue that you yourself are setting up a "straw man". As I said and you are well aware of you don't have to maintain powered flight to orbital altitude. You just attain sufficient velocity to achieve orbit, point it upward That minimum altitude is around 70km, still too high for a cable. It would be too much aeroheating below that. still to high for an anchor. So still not viable.It is not even worth testing.
RGClark - 6/3/2008 9:57 PMQuoteJim - 6/3/2008 9:14 PMHere is another nail in the coffin. Launch vehicle trajectory is in the lower corner.The cables are shaped wrong and spend too much time in the lower atmosphere. Also the multiple balloon has catenary curves that would go up and down several KM.End of story Obviously, there wouldn't be a great dip in the cable if the balloon supports were only separated by for example 10 meters, or if the cable was supported continuously along its length.
Jim - 6/3/2008 9:14 PMHere is another nail in the coffin. Launch vehicle trajectory is in the lower corner.The cables are shaped wrong and spend too much time in the lower atmosphere. Also the multiple balloon has catenary curves that would go up and down several KM.End of story
Jim - 6/3/2008 10:34 PMObviously this concept is not going to work on any level
Avron - 6/3/2008 11:07 PMQuoteJim - 6/3/2008 10:34 PMObviously this concept is not going to work on any levelCome now Jim.. it will work on the ground..
pippin - 7/3/2008 4:33 AM[...]But a train going 7km/s, wow, THAT would be something... Would LOVE to see the plasma trail it generates...
pippin - 7/3/2008 1:33 AMJim, Rob, you are both wrong. The cable would point more or less straight upwards. I still didn't see the concept on how to apply the horizontal force necessary to keep a bend. Any bend will be at the low end of the cable the top end will point 90° into the sky no matter how many balloons you apply.But a train going 7km/s, wow, THAT would be something... Would LOVE to see the plasma trail it generates...
At that point, I think it'd be wise to stick the thing inside a tube with vacuum. Even though it breaks the totally-cool plasma trail effect.
RGClark - 7/3/2008 12:13 PM[...]. The SR-71 Blackbird uses jets that can operate to 100,000 ft, 30 km:LOCKHEED SR-71 BLACKBIRD.http://www.abovetopsecret.com/pages/sr71.html and the NASA's Helios solar powered plane can operate at nearly 100,000 ft:NASA Solar Aircraft Sets Altitude Record; Communications And Environmental Breakthroughs Expected.http://www.sciencedaily.com/releases/2001/08/010815081052.htm Bob Clark
RGClark - 7/3/2008 12:25 PMQuoteJim - 6/3/2008 9:13 PM...Now I know what perpetual motion machine "inventors" are like No, what you are experiencing is what it's like to argue against a proposal that can actually work.
Jim - 6/3/2008 9:13 PM...Now I know what perpetual motion machine "inventors" are like