Not quite due north. I'm budgeting for a very, very large contingancy delta-v, around a kilometer a second, just in case. Part of the design is to be able to cope with unexpected stage underperformance, or the flame going out.
Fuel is cheap.
"Mike" wrote | Well the availability of whatever ore the Curies purified radium | from is presumably a little harder to get now :-)
And can you imagine the expression on a buyer's face when you answered "no, there's no asbestos in the house, but we did do some radiology experiments in the scullery"
Owain
No idea - the usual "ores" for the back-bedroom Teller-wannabees these days are that old favourite, thorium from caravan gas mantles, or else americium from smoke detectors.
The Curies went through _tons_ of pitchblende. We just don't have the space to do it these days.
I think most, maybe all, don't have it anymore.
Damn them and their ways to constantly foil my evil plans!!!
Sam
And it killed her.
It may well have killed him, too, but he got run over by a cart, first.
calculations
Fascinating: I thought at first you were making it up! AFAIK noone has done anything like this, the X-prize contestants aren't anywhere near orbital velocity and the performance needed in terms of fuel goes up as the square of the velocity, and you reckon you've a km/sec delta-v as contingency! I am all admiration Sir! I've seen other rocket groups' websites ( one group is called MARS ) but none are quite as ambitious. The amount of human effort needed to achieve the kind of performance you specify is considerable. Any chance of a technical overview or is it all under wraps?
Andy.
Aren't they ? I thought the prize had been won. Don't they actually have to achieve orbit to win ?
No just a specific height, 100km IIRC, their trajectory was something like this ...
^ / \ | | | | | | | | / | / \ >-/ \->
Wouldn't "orbital velocity" vary depending on the height you wished to orbit at? Perhaps someone was thinking of "escape velocity" which is about 26,000mph
Whay does the shuttle and Spacelab need ? That sounds a good start.
So this Virgin "spaceplane" they're building won't even get you near a proper orbit then ? Does it reach the point where you feel weightless (other than when it goes into a controlled dive) ?
This is a fair point, but it would be quite a bit of work none the less. Got any diagrams etc. of homebuilt kit?
Apparently the ISS is currently 349km high and whizzing over Egypt
From what I heard the Virgin/SpaceShipTwo will go higher than the SpaceShipOne, and you will get several minutes of weighlessness for your $200,000
ISTR it can be done with a compressor and pair of concentric copper pipes. These are coiled up and inserted into a thermos or dewer. Air is pumped down the central one which has an expansion jet on the end which cools the air. The cool air is recovered back up the outside one which further cools the air coming down the central one, until eventually the air gets cold enough to start liquifying when it leaves the expansion jet. At least, this is my recollection of one way of doing it from O-level physics.
There appear to be some details missing from this, like where the heat gets dumped. Probably, the compressed air is cooled back down to room temperature before it enters the coil to be further cooled by the returning air. (It is not necessary to send the same air round and round the system.)
Obviously, starting with air, you end up with liquified air rather than nitrogen. The boiling points of nitrogen, oxygen and argon are near enough you'll get them all ISTR.
This subject came up a few months back, as I was considering trying to do this with a compressor from a freezer. I did google around thinking there was probably a secret society of low temperature hobbists out there doing this, but came up with nothing, so if there is, they are very secret. I couldn't even find a description of the process above which I recall from my O-level physics lessons.
It was to give him the reputation of a hard man but his wife found him rather cold so she broke it off.
Apparently they all give him the cold shoulder these days.
So be careful!
No. Yes. No.
I imagine one could make LN2 @home with vortex tubes. As air spins through the tube it separates into hot and cold streams. Dump the hot and put the cold through another vortex tube, etc.
Air must be dried for these experiments, otherwise ice will quickly clog the cooling kit.
If you want to build your own radioactive speriments, theres a newsgroup for it, free.uk.nuclear-device, or something like that.
NT
At the moment I'm working on ancillery systems, guidance and stuff, and working out best ways of making cheap small regeneratively cooled rocket engines.
In a way, it's not very ambitious. Some groups are going for things like single stage or 2 stage to orbit.
This means that you almost have to go to extreme lengths to reduce the weight of the vehicle, and are very highly penalised by small size due to having to push through the atmosphere. (adding a percent to the dry mass of a 1 or 2 stage vehicle can often be the difference between having a payload, and not being able to reach orbit empty.
If you're willing to go with more stages, then in some ways things get easier. You throw away empty tanks along the way, which means that you don't have to have one big very light tank.
You reduce the total mass you have to take to orbit, as the size of rocket engine on the upper stages is smaller, hence lighter, so you don't have to worry so much about the takeoff engines weight, or make it so that it can be throttled down so far, and in some cases can eliminate the need for the engine to be restartable.
All of this is good, as it makes the hard bits (rocket engine, ...) a little easier, and means that instead of needing Aluminium-Lithium tanks, you can go with not very good steel or fiberglass, can use screwfix 2.99 full-bore ball valves instead of machining something exotic and light, ...
Yes, it may use 25 times more fuel than a 'good' rocket, but fuel is cheap.
(I'm aiming for a cost for the whole thing of only 10K )
This is for around a kilo to LEO. For much more, this approach starts to break down, and you need to go to appropriate high technology in some parts in order to keep costs down. It doesn't make sense to (for example) make a much larger rocket out of simple to construct steel, if the overall cost is lower with better harder to weld steel.
I suspect there is a fly somewhere in the ointment with that idea, as I'm sure someone would be making & selling an LN2 generator based on vortex tubes if it was practical. Current LN2 generators that I've seen are somewhat more complex...
Maybe it's just an issue of efficiency - I suspect such a system would need a lot of air. The graph here
I'm also wondering how easy these are to make - commercial ones seem quite expensive if all they are are is essentially a cast/machined chamber. Some info I saw says that rotational speeds of the air were of the order of 1000000RPM, so I'd guess surface finish would be pretty important to avoid friction and turbulance losses.
However if they can be made to work at high pressures, maybe there would be some mileage in compressing, cooling to room temp, further cooling in a vortex and then expansion...?
I imagine one couldn't ! Fussy little blighters, vortex tubes.
I thought most of that was on these news groups
Dave
One of the best things about this ng is that it has plenty of the real stuff (and this time I *do* mean Intelligence)
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