Mach 6? I thought they were talking 6 km/s. Thats about 3 times as fast, and ALMOST orbital.Aero wrote: Quicklaunch, Inc. indicated, in the video, that they would launch at a relatively steep angle, exiting the atmosphere quickly at mach 6, then circularize with the kick motor.
Affordable LEO Fuel Depot Construction Tech
KitemanSA wrote:Aero wrote:
Quicklaunch, Inc. indicated, in the video, that they would launch at a relatively steep angle, exiting the atmosphere quickly at mach 6, then circularize with the kick motor.
Mach 6? I thought they were talking 6 km/s. Thats about 3 times as fast, and ALMOST orbital.
I did it, and I knew better, too. Mach 6 ain't even close to orbital velocity at LEO.Aero wrote:I watched the video again and I must apologize for some bad numbers. This time I wrote them down so here are correct ones:
Interestingly, the record muzzle velocity for a hydrogen gas gun is 11.2 km/sec which equals escape velocity.
Quicklaunch expects to fire a 1 km long gun with a nozzle velocity of 9 km/sec, expecting 6 km/sec (not mach 6, my bad) at LEO altitude.
Quicklaunch expects to circularize by using a kick motor to achieve 7.2 km/sec, orbital velocity at LEO. The kick motor will use LOX and RGP, with an ISP ~ 340 sec, burn time about 100 seconds, and so forth.
Will it work? I don't know but the video is pretty convincing.
A question - does anyone know how to keep a liquid filled container under high acceleration inside a gun barrel from transferring pressure laterally to the bore of the barrel and making like a brake? It seems that a rigid scram jet and a liquid filled tank should behave quite differently when shot down the barrel of this cannon.
Aero
Sabot.A question - does anyone know how to keep a liquid filled container under high acceleration inside a gun barrel from transferring pressure laterally to the bore of the barrel and making like a brake? It seems that a rigid scram jet and a liquid filled tank should behave quite differently when shot down the barrel of this cannon.
Engineering is the art of making what you want from what you can get at a profit.
Yess, but ...Sabot.
A tank, a tall tank containing liquid, a tall, liquid filled tank accelerating at 5000 gees. Hydraulic pressures on the bottom if the tank and Sabot would be enormous, over 10,000 psi, I guess. (water)
A Sabot, a very rigid Sabot.
But it may not be so bad. The tank is just a little heavy is all.
For perspective, recall that the gas pressure in the gun barrel is 15,000 psi and the gun barrel is lined with 2 inches of high strength steel. I doubt the tank will be made of 2 inches of high strength steel. They plan to launch 1000 pounds of payload. That much water is 1000/60 cubic ft of water, about 16.7 cubic ft. So, I guess my question is, how much of the 1000 lb. payload is liquid and how much is tank? Of course I have not considered the same problem which arises in the liquid rocket fuel and fuel lines in the third stage of the rocket, the orbital insertion kick motor.
Last edited by Aero on Sat Jan 30, 2010 3:50 pm, edited 1 time in total.
Aero
I'd kind of like to see these folks start talking with the tether folk. Use this for the first ~5kps and the tether for the final. No rocket needed except for small loitering / guidance thrusters to increase allowable capture time. If the current design would put 5000kg into LEO, the tether option would allow maybe 8000kg instead, with a much cheaper canister (no aerospike rocket needed.
The tether then ccould put the fuel canisters (or the fuel from these heavy canisters in a light tank) into transfer orbit for Lunar orbit or toward Mars as way-stationed provisions.
The tether then ccould put the fuel canisters (or the fuel from these heavy canisters in a light tank) into transfer orbit for Lunar orbit or toward Mars as way-stationed provisions.
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CaptainBeowulf
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Captain B,
In a word, no.
If Australia were to build a launch facility, I would expect they would do it for them.
But let's see, New Mexico just opened their spaceport. http://www.spaceportamerica.com/
By the way, their head honcho Steve Landeene keeps bugging me about when he can expect delivery on his BFR (he has a mandate to use clean energy and he would really love to have the first operating Polywell powerplant). They are approved for launches, and they are right up against White Sands. So, bring in a subway tunneling outfit and start boring ... pick a direction to give as close to an equatorial orbit as practical. It would be really cool if it wound up running under Roswell or Area-51 (alas, the angle would be wrong). Build the bulk of the gun into the tunnel and then run it up the mountains, facing east.
Any of these land-based 1300 km guns would require turning the projectile upward after a long horizontal run. Gotta keep the radius gentle so as not to squish the passengers to jelly, and engineering the gun so it can do this will be a chore. But the Germans had a machine gun that could shoot around corners.
In a word, no.
If Australia were to build a launch facility, I would expect they would do it for them.
But let's see, New Mexico just opened their spaceport. http://www.spaceportamerica.com/
By the way, their head honcho Steve Landeene keeps bugging me about when he can expect delivery on his BFR (he has a mandate to use clean energy and he would really love to have the first operating Polywell powerplant). They are approved for launches, and they are right up against White Sands. So, bring in a subway tunneling outfit and start boring ... pick a direction to give as close to an equatorial orbit as practical. It would be really cool if it wound up running under Roswell or Area-51 (alas, the angle would be wrong). Build the bulk of the gun into the tunnel and then run it up the mountains, facing east.
Any of these land-based 1300 km guns would require turning the projectile upward after a long horizontal run. Gotta keep the radius gentle so as not to squish the passengers to jelly, and engineering the gun so it can do this will be a chore. But the Germans had a machine gun that could shoot around corners.
http://www.geekologie.com/2007/12/corne ... around.php
http://en.wikipedia.org/wiki/Krummlauf
http://en.wikipedia.org/wiki/Krummlauf
One unusual addition to the design was the Krummlauf; a bent barrel attachment for rifles with a periscope sighting device for shooting around corners from a safe position. It was produced in several variants: a "I" version for infantry use, a "P" version for use in tanks (to cover the dead areas in the close range around the tank, to defend against assaulting infantry), versions with 30°, 45°, 60° and 90° bends, a version for the StG 44 and one for the MG 42. Only the 30° "I" version for the StG 44 was produced in any numbers. The bent barrel attachments had very short lifespans – approx. 300 rounds for the 30° version, and 160 rounds for the 45° variant. The 30° model was able to achieve a 35x35 cm grouping at 100 m
Engineering is the art of making what you want from what you can get at a profit.
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CaptainBeowulf
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Yeah, I remember some old NASA artist's impressions of a spaceplane accelerating along a track run up the side of a mountain.
The German gun example is interesting, but typical of the German war effort: too much attention to detail. The gun would have been very useful in one-off tactical situations, but then it would be worn out... as with other stuff, they would probably have been better off mass producing standardized designs (1000 Mark IV panzers would have probably been a greater threat than, say, 200 or 300 Tigers and Panthers).
The German gun example is interesting, but typical of the German war effort: too much attention to detail. The gun would have been very useful in one-off tactical situations, but then it would be worn out... as with other stuff, they would probably have been better off mass producing standardized designs (1000 Mark IV panzers would have probably been a greater threat than, say, 200 or 300 Tigers and Panthers).
Yes, the grease-gun attachment had a relatively specialized application. You might only use it a few times, or once. But picture you are a German infantryman, around the corner from advancing Russians in an urban warfare environment. If you are telling your grandkids about the episode, you may remember the 250 rounds you got off from your $10 junkwaffle machine gun quite fondly.
As for the application showing excessive attention to detail, our alternative today to dealing with enemies around the corner includes robots like Packbot, UAV's such as Shadow 200, air cavalry, and a whole branch of the armed services, plus spy satellites. All of which will be glowingly told to many grandchildren one day by a large number of soldiers. Evidently, and fortunately, the Germans had insufficient neat ideas to compensate for a very bad choice of enemies.
And if engineering a bend in a space cannon makes it go from a non-starter to a working launch system that drops launch costs by a factor of a modest integer, I'm sure a small army of engineers will jump at the chance.
It occurs to me that more than one technology might be used in this thing. For one propulsion system to be applied over a range of Mach 20 seems rather demanding for one tech. For my money, some form of maglev may be called for to keep the thing off the walls, especially in the turn, although maybe a gas boundary layer would suffice.
I still see huge practical problems with dense atmosphere. Just from the drag perspective, picture what it would be like to slam into air with 7000 psi on the front of the vehicle. The deceleration is likely to be as bad as being shot from the gun!
A New Mexico launch would be around 1 mile altitude, maybe a mile and a half. Off the top of my head, something like 90% of sea level density. Even the top of Everest is still higher density than we would like.
On Mars, the surface is around 1% of Earth sea level density. That is probably workable, and orbital velocity is much lower, too. To reach that atmospheric density on Earth, you would need the muzzle at 100,000 ft.
As for the application showing excessive attention to detail, our alternative today to dealing with enemies around the corner includes robots like Packbot, UAV's such as Shadow 200, air cavalry, and a whole branch of the armed services, plus spy satellites. All of which will be glowingly told to many grandchildren one day by a large number of soldiers. Evidently, and fortunately, the Germans had insufficient neat ideas to compensate for a very bad choice of enemies.
And if engineering a bend in a space cannon makes it go from a non-starter to a working launch system that drops launch costs by a factor of a modest integer, I'm sure a small army of engineers will jump at the chance.
It occurs to me that more than one technology might be used in this thing. For one propulsion system to be applied over a range of Mach 20 seems rather demanding for one tech. For my money, some form of maglev may be called for to keep the thing off the walls, especially in the turn, although maybe a gas boundary layer would suffice.
I still see huge practical problems with dense atmosphere. Just from the drag perspective, picture what it would be like to slam into air with 7000 psi on the front of the vehicle. The deceleration is likely to be as bad as being shot from the gun!
A New Mexico launch would be around 1 mile altitude, maybe a mile and a half. Off the top of my head, something like 90% of sea level density. Even the top of Everest is still higher density than we would like.
On Mars, the surface is around 1% of Earth sea level density. That is probably workable, and orbital velocity is much lower, too. To reach that atmospheric density on Earth, you would need the muzzle at 100,000 ft.
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CaptainBeowulf
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I completely agree that we should have attention to detail and build specialized, low-production run weapons today, because we have the luxury of doing so. WWII was a mass-production war, though, so the best strategy then was to focus on production of relatively few, standardized designs. The Germans often over-reached; for instance, most of the first run of Panthers used at Kursk broke down early in the battle, and Tigers had major transmission problems due to their 60 ton weight.
Actually, I think the Germans' neat ideas, like jet fighters, electro u-boats, Panthers, nebelwerfer rocket launchers etc. would have been very problematic if they had been able to mass produce them. We came up with neat ideas that we were able to mass produce - proximity fuses for AA and artillery shells; drop tanks for Mustangs - and they really helped us.
I suspect with modern technology we could do a space cannon with a bend in it.
Also, I think that space cannons would work really well on Mars and the moon due to smaller gravity wells. On Earth, a maglev launch rail to get a spaceplane going fast enough that it could kick right into ramjet mode when it flies off the top of a mountain would probably be more feasible in the near-term.
Actually, I think the Germans' neat ideas, like jet fighters, electro u-boats, Panthers, nebelwerfer rocket launchers etc. would have been very problematic if they had been able to mass produce them. We came up with neat ideas that we were able to mass produce - proximity fuses for AA and artillery shells; drop tanks for Mustangs - and they really helped us.
I suspect with modern technology we could do a space cannon with a bend in it.
Also, I think that space cannons would work really well on Mars and the moon due to smaller gravity wells. On Earth, a maglev launch rail to get a spaceplane going fast enough that it could kick right into ramjet mode when it flies off the top of a mountain would probably be more feasible in the near-term.