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Post by Lensman on Feb 23, 2005 13:03:56 GMT
are we agreed that the Martians would most likely use some 'combustionless' propulsion system for their aircraft? I can't imagine carting tons and tons of fuel from Mars, and they couldn't be assured of getting compatible fuel here. Not necessarily. They came prepared to build industry for constructing new machines starting by mining raw materials, so I think it entirely possible they came prepared to refine or manufacture aviation or rocket fuel. If we must put it into modern terms--frankly I think that's a mistake, but if we must--then hydrogen and oxygen can always be produced in quantity so long as you have electricity and a supply of water. A rocket doesn't need wings, so one could argue that indicates it's a jet, but OTOH the rocket could have been used to quickly get it to altitude, then throttled back to "cruise" along on a bombing or transportation run. Very wasteful of fuel, tho. But again, Wells didn't know all this. On the other-other hand, I can't think of any *theoretical* reason why liquid hydrogen couldn't be used as a jet fuel. Mix it with air, and it should burn just fine.
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Post by lanceradvanced on Feb 23, 2005 15:06:51 GMT
Interesting that others in this thread think they Martians brought the flying machine with them, in sections. I've always assumed that, as it was an experimental machine, it was built here on Earth. After all, the Martians were mining ore and refining aluminum... er, "aluminium" since it was in Britain. I lean towards a little bit of both, the Martians brought some prefrabricated components along with them, power plants and psuedo-muscular actuators, and possibly the HeatRay cameras, structural componets being fabricated on site, as the martians recycled the cylinders.
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Post by lanceradvanced on Feb 23, 2005 15:16:59 GMT
So far as I know, there aren't any modern aircraft that climb that quickly. And yet this was a large craft; what the heck were they using for propulsion? Some interesting speculations in this thread. F-14 Tomcats have a Vertical climb rate of 30,000 feet per minute, that's enough to get higher than many types of low altitude clouds in seconds..
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Post by Topaz on Feb 23, 2005 18:37:15 GMT
On the other-other hand, I can't think of any *theoretical* reason why liquid hydrogen couldn't be used as a jet fuel. Mix it with air, and it should burn just fine. You can. The first gas turbines intended for aircraft - those of Hans von Ohain - were fueled by hydrogen. The downside of liquid hydrogen is the usual thing they run into with rockets and other applications - low density (and therefore high volume), difficult to handle the cryogenics, metal embrittlement, etc. I suppose it could be done - the Martians certainly had access to both water and electricity - but if we assume that their civilization was largely underground and that the atmosphere of Mars for the story was the same as it is today, they'd have little or no experience in chemically-fueled gas turbines. My own guess is that they'd stay conservative and use a derivation of the same systems they were familiar with from their own planet, but we're so far beyond the framework of the book here that anything is possible. One thing I would confidently state is that the engines wouldn't be fueled by the combustion of hydrocarbons. Such would mean they'd either have to bring sufficient supplies with them - doubtful - or be assured that they could find and refine raw petroleum at or near their landing sites, which is too sketchy for a military operation, IMHO. The biggest thing that would determine the nature of the propulsion system would be the defined mission of the Flying Machine. The consensus here seems to be that it would be what we would call a 'reconnaissance bomber', capable of both scouting the enemy and attacking them. The evident size of the vehicle suggests either long range, large weapons load, or both. If the intent was to use the UK as a base of operations for attacking Europe and Asia, then I would think range would be a primary requirement. It's entirely possible to attack the Americas by landing cylinders into the more remote areas and establishing your base of operations there, moving into more populous areas once those 'beachheads' have been established. This is not something you could really do with Europe, since the UK was the dominant military power of the time and was isolated from ground assault by the Channel. Better to 'cut off the head' immediately, then use that isolation to your advantage. In all of these cases, range becomes a driving requirement. The Black Smoke was an extremely effective area weapon, so payload could be sacrificed for range, if necessary. For range, you need lots of span, lots of wing area, and a fuel-efficient propulsion system to keep weight down and payload capabilities up. My vote is for nuclear - giving virtually unlimited range and no fuel requirement aside from the reactor - but pretty much anything mentioned here except for rocket power could be stretched to fit the bill, perhaps.
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Post by TOMAHAWK on Feb 23, 2005 21:37:18 GMT
So are we looking at say a nuclear powered martian version of a Stealth Bomber / NA Flying wing as seen in the Pal version
Strange ..How come that the Martians KNEW about how to build a flying machine that would work in our air ..given that Mars is a substantially different enviroment to Earth ....for example an F14 would not work on Mars,
Also ..they must have had plans in place for flying machines ..I cannot see them just randomly designing one when the got here, so they MUST have known the thing WAS going to work ....
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Post by Topaz on Feb 23, 2005 22:23:01 GMT
Well, I'm thinking nuclear-powered flying wing, but that's just my little fantasy. ;D Probably closer to the '50's version, since Stealth isn't a design requirement. The only fly in the oitment (given our known technology) is the reactor shielding to protect others near the 'airfield'. Shadow shielding for the flight crew would be manageable, but completely shielding the reactor would literally weigh tons. People have suggested magnetic fields, which would work for the particle radiation, but only thick, dense stuff stops gamma.
But yes, if I was a Martian aerospace engineer, I'd build a nuclear powered flying wing with thrust-vectoring for VTOL, assuming the reactor/shielding is light enough. If the reactor provides energy for high-bypass turbofans, I can't imagine that it's impossible.
Aerodynamic equations for subsonic and low-supersonic aircraft aren't terribly 'picky' about what gasses you're flying through. They only care about the density of those gasses, for the most part. There's some slight changes due to the differing viscosity of the gas mixture, but the Martians would likely be able to determine both pieces of information from remote observations, or a simple probe. After that, it's just grind and crank on the equations as if you were designing for home, using the atmospheric density values for the destination planet. The NASA has worked out designs for unmanned airplanes for Mars, which isn't any different than doing it the other way 'round. One of them was actually proposed for a mission a year or so ago, but was rejected in favor of something else.
I agree completely that the Martians would've had the design for the 'Earth plane' all worked out in advance. That's really not the sort of distraction you want to do in the middle of a war, if possible. Personally, if it were up to me, I'd have the thing disassembled in one of the cylinders, for assembly on Earth after landing. Once the aircraft has been assembled, you still need a flight-test, but if you're pretty sure of the environment and design conservatively, there's no reason that has to be a protracted affair. My own theory is that the Martians were still doing some flight testing when the disease(s) overtook them, and hadn't yet begun military operations with the vehicle. I think the "And as it flew, it rained down darkness upon the land." passage is poetic metaphor for nightfall rather than actual bombing with Black Smoke, although I know others see it differently.
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Post by Lensman on Feb 24, 2005 19:40:29 GMT
F-14 Tomcats have a Vertical climb rate of 30,000 feet per minute, that's enough to get higher than many types of low altitude clouds in seconds.. Wow! I stand corrected (sit, actually ). Thanx for the info, Lanceradvanced!
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Post by Lensman on Feb 24, 2005 20:52:42 GMT
Agreed that while burning hydrogen would be possible, it's far from the best solution. Even with a fuel which has a better energy/weight ratio, like kerosene or aviation fuel, you run into the basic problem with large rocket-propelled vehicles: That most of the weight must be fuel. And I think we're all agreed that Martians wouldn't haul bulk rocket/aviation fuel from Mars. So I agree that some form of propulsion not requiring fuel would be the best solution. A practical solution to that not-so-minor problem has eluded industry here on Earth so far! However, as has been pointed out, the Heat Ray is capable of a remarkable degree of heat transfer. And while it's true that trying to use it directly to heat the air would be extremely inefficient, I think it could be used indirectly. I'm not exactly sure how that would be done; perhaps line the rocket's "combustion" chamber (altho no actual combustion is going on, of course) with ceramic kiln bricks, and use a heat ray on low setting to heat up the bricks? Doesn't sound like a very effective method of heat transfer. Frankly, air is a fairly good insulator, so I'm not sure what the most efficient method of heating would be. However, if it's possible to use a nuclear reactor to heat air for "combustionless" propulsion, then it should be possible to do the same with a heat ray, even if it was a very inefficient use of power. Consider the power required to set a forest ablaze with a heat ray. Clearly, power requirements are not a problem for the Martians. I think the biggest problem in using the heat ray indirectly for a propulsion device would be getting rid of the waste heat. But again, if a nuclear reactor has been used successfully on an airplane, I see no reason why the heat ray couldn't be used in a similar fashion. If it's only emitting infrared radiation, there's no need for heavy shielding. ~~~~~~~~~~~~~~ I agree that the Martians would have brought critical components with them in the cylinders. I believe the flying machine's body and wings were constructed here, though. The scene where the handling machine processes aluminium bars suggests that to me; aluminium is certainly what you'd want to build the structural parts of a flying machine. I also agree that designing a flying machine for Earth conditions shouldn't be that hard for the Martians, especially if they're more intelligent than we humans. As has been pointed out, we're currently designing flying machines for Mars conditions here on Earth. Guys, I just have to say: This is the most interesting online discussion I have ever participated in. The imagination and knowledge displayed by you is simply amazing!
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Post by McTodd on Feb 24, 2005 23:27:24 GMT
In the Pearson's serialisation, the Narrator has more to say in the Epilogue about the flying machine than in the novel:
Note that when Wells edited it for the novelisation, the machine was found in the main pit at Primrose Hill, not in Kilburn (which, for non-UK readers, is in west London).
So, the machine was definitely used for bombing missions, and the Narrator speculates that the Martians fabricated it on earth.
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