|
Post by Zholud on Apr 6, 2005 23:02:13 GMT -5
On inertia dampenersI’m convinced they are not used by the Imperium. Indirectly this can be because they were not in STC – who needs to construct them unless you got orbiting ship… Another more important note – if they were allowed as a tech to Imperium, I guess they’d be actively used in e.g. artillery, which seems is not the case.
|
|
|
Post by Briareos on Apr 7, 2005 2:42:15 GMT -5
A lot of "high-tech" techonologies are available to the Imperium, which doesn't mean that they are commonly used in everyday life/warfare. Anti-grav tech is a good example of this.
Controlling the way technology is used is one more way to control the populations of the Imperium. Some tech is scarce because it shouldn't be made widely available, not because it can not be produced "en masse".
|
|
|
Post by Tynesh on Apr 7, 2005 7:05:51 GMT -5
The arguement over inertial dampeners really depends on how the drop pod slows as it enters the final stages of decent. It would be impossible for a pod to hit the ground at 12,000 kph and still survive. If the descent is too slow though the pod becomes vunerable to enemy fire.
Considering the damage that occurs to airplanes to when they hit the ground at several 100 kph, even though they ain't designed to hit the ground, would be much worse if a drop pod (hard solid designed to take damage) were to hit the dirt at much over 1000 kph.
Tynesh
|
|
|
Post by Sojourner on Apr 7, 2005 7:41:03 GMT -5
Planes tend to drop to the ground fairly slowly even though they're going very fast 'along', whereas drop pods fall straight down. Not quite the same thing.
|
|
|
Post by Briareos on Apr 7, 2005 7:47:22 GMT -5
The quick deceleration of the pods isn't a problem. Whether by parachutes or retro-rockets, it is within the realm of the believable that drop pods could be slowed from several thousand kilometers per hours to a few hundreds (at about 200 m from the ground ?), to a few tens (at about 25 m ?). The burst of flame/energy from the retro-thrusters also comes in handy to clear the immediate landing area from potential hazards such as enemy troops or landmines.
I think the true question really is : How much g's can marines, marine equipment and marine vehicles handle ? If it's "a lot", then inertial dampers are redundant as the stress of deceleration can be handled by the cargo. If it's just "some", then the pressure of deceleration needs to be handled in some way. It should also be noted that the inertial dampers need not be "energy fields" - they could as well be mechanical or liquid.
|
|
|
Post by Sojourner on Apr 7, 2005 8:50:17 GMT -5
I'd guess that marines can still function comfortably at 6Gs or so, whereas I believe this is the blackout point for humans. By the time he reaches 10Gs he'll be gritting his teeth. Blackout threshold would be about 14Gs, but even then it won't cause much lasting damage.
|
|
|
Post by Philip on Apr 7, 2005 9:14:21 GMT -5
No, they are horrendously high-tech. I wasn't advocating using them, rather questioning the image and indicating the directions that one might take if you buy solely into the image rather than questioning that image. (I realise that you're not addressing this to me, but I did mention them as well!) I know they are horrendously high-tech, it just seems odd that inertia dampeners don’t raise an eyebrow but power-fields set off alarm bells. As stated elsewhere, you see the Image and go "Hey, let me create a reason why that is correct!" I, on the other hand, look at it and go "So, the Image is incorrect, how might it actually work?" Is this tongue in cheek? Forcefields as described in the 'fluff' - not your 'magic field creators', Philip - wouldn't quite work as an airbag, IIRC. I’m not saying the force field is acting as an airbag, I’m say the ground that is rendered to squishy ‘liquid/ gas’ by the power-field is acting as an air bag. On inertia dampenersI’m convinced they are not used by the Imperium. Indirectly this can be because they were not in STC – who needs to construct them unless you got orbiting ship… They must have such devices for inter-stellar star-ships as they can get to the edge of the soar system in short order, and the crew and passengers aren’t pinned to the back wall when they make a trip. Another more important note – if they were allowed as a tech to Imperium, I guess they’d be actively used in e.g. artillery, which seems is not the case. Depends, it may be tactics: military artillery can be captured and turned aginst the Imperium, and therefore fall into the wrong hands, whereas drop pods may have temporary inertia dampeners/ power-fields that burn out in the drop and can’t be reused (without a refit) or reverse-engineered. As a note: I think anti-grav would be easier to make than an inertia dampening field. A lot of "high-tech" techonologies are available to the Imperium, which doesn't mean that they are commonly used in everyday life/warfare. Anti-grav tech is a good example of this. Very true, most high-tech is limited to the military and Imperial structures. For example: Imperial Guard have grav-chutes (low powered personal anti-grav), but I’m sure that civilians can’t get hold of this tech. Controlling the way technology is used is one more way to control the populations of the Imperium. Some tech is scarce because it shouldn't be made widely available, not because it can not be produced "en masse". I agree, much of the higher tech is available based on ones standing in the Imperium. The arguement over inertial dampeners really depends on how the drop pod slows as it enters the final stages of decent. It would be impossible for a pod to hit the ground at 12,000 kph and still survive. Depends on tech, going to the speed of light in the blink of an eye is far more extreme that a drop pop hits a rock hard surface at 12,000 kph. If the descent is too slow though the pod becomes vunerable to enemy fire. I think full speed all the way – think of the image! ( ) Considering the damage that occurs to airplanes to when they hit the ground at several 100 kph, even though they ain't designed to hit the ground, would be much worse if a drop pod (hard solid designed to take damage) were to hit the dirt at much over 1000 kph. An Airplane with inertia dampening field/ power-field could nose dive into the dirt and just end up buried – but unscathed. The quick deceleration of the pods isn't a problem. Whether by parachutes or retro-rockets, it is within the realm of the believable that drop pods could be slowed from several thousand kilometers per hours to a few hundreds (at about 200 m from the ground ?), to a few tens (at about 25 m ?). Rapid deceleration from 12,000 kph to stop in 200m is going to kill without an inertia dampening or even full negating field (anyone what to do the calculation? At a rough guess this type of deceleration is going to tear the flesh from the bones and simultaneously snap the bones into mush. I’ll resist saying it will turn the marine to soup, but definitely some kind of gloop). The burst of flame/energy from the retro-thrusters also comes in handy to clear the immediate landing area from potential hazards such as enemy troops or landmines. This is nice, though a power-field would destroy mines on contact by breaking the bonds between the atoms (so an explosive is no longer an explosive). I think the true question really is : How much g's can marines, marine equipment and marine vehicles handle ? If it's "a lot", then inertial dampers are redundant as the stress of deceleration can be handled by the cargo. Not at the level of stress we’re talking about here. If it's just "some", then the pressure of deceleration needs to be handled in some way. It should also be noted that the inertial dampers need not be "energy fields" - they could as well be mechanical or liquid. That’ll work on very low speeds (sub 150 kph) much like ‘crash foam’, but at 12,000 kph it wouldn’t work as internal pressure would be far to high.
|
|
|
Post by Tynesh on Apr 7, 2005 11:13:34 GMT -5
Yes in fact it would make what ever it landed onto actually have a very large explosive force. Conventional explosives are a chemical that is easily combusted - in doing so a large complex molecule (Trinitro tolulene TNT) is rapidly converted into CO2, NO2, H20, H2, O2 plus lots of other intermediates. It is the sudden creation of multiple molecules that creates the explosion and out rushing of gases.
A-level chemistry - some rule states that a set number of molecules will have a certain pressure in a confined volume - doubling the number of molecules doubles the pressure.
This could then create a large volume of gases right where the pod lands blasting the pod away from the landing spot - if the landing jet is still hot then some of the gases could possibly combust as well.
Not too sure how accurate the figures on G-forces are?
The airforce has suits that incorporate bladders that fill with water around the legs of fighter pilots when under high G's in turns etc. This forces the blood back up into the body.
You would also have to think of the physiological aspects of the marine at High G, lots of blood rushing to/from head will still affect them. Having two hearts also suggests that they would have higher blood pressure etc. Not good if all of it tries to go to your head at once.
Yes marines are uber humans but they all were originally human, they have been upgraded not totally reverse engineered!
We have to assume that the drop pods DO NOT hit the ground at full wack! And that they need some system to prevent the effects of extreme G (it will be very high) on the human cargo as the pod slows down.
|
|
|
Post by Philip on Apr 7, 2005 11:50:40 GMT -5
Yes in fact it would make what ever it landed onto actually have a very large explosive force. Conventional explosives are a chemical that is easily combusted - in doing so a large complex molecule (Trinitro tolulene TNT) is rapidly converted into CO2, NO2, H20, H2, O2 plus lots of other intermediates. It is the sudden creation of multiple molecules that creates the explosion and out rushing of gases. In this instance all molecules are going to fall apart into component atoms, some actually absorb energy in breaking bonds other release it – on balance? There is not doubt there would be a huge explosion, even if there where no explosives…. A-level chemistry - some rule states that a set number of molecules will have a certain pressure in a confined volume - doubling the number of molecules doubles the pressure. If all molecules break apart into component atoms, it would make a giant air cushion of explosive gas (pod protected by power field). Mind you I do like the retro-rocket clearing the area, and adds another dynamic. Perhaps the pods do use retro-rockets, they just they can slow it down from 12,000 kph to 0 kph in 200m, but will take of the edge (or are used to ensure correct landing velocity – the rockets are there to resist high gravity on large worlds and keep the pod impact within spec) This could then create a large volume of gases right where the pod lands blasting the pod away from the landing spot - if the landing jet is still hot then some of the gases could possibly combust as well. Isn’t this what we want? The explosion of even normal material would provide the extra counter force powerful of enough power to stop the 12,000 kph drop from burrowing too deeply onto the crust. All these tremendous force would certainly explain the format of the crater, rather than a patch of scorched earth.
|
|
|
Post by Tim_C on Apr 7, 2005 13:00:26 GMT -5
Too true there Philip. I did a couple of rough calculations, and came up with the figure that at terminal velocity (12000kph), with 5 marines weighing 3/4 of a tonne each in the pod, the pressure exerted by the base of the pod is: 1.5 E16 N/m^2 That is roughly 1.5 E+07 GPa !!! A lot of pressure I think you'll agree... Of course, I didn't take into account air resistance, but that would be appreciable for a flat-bottomed projectile (which is what the pod is). So, a pod slapping straight into the ground at full speed, is going to create quite a bang, more than the nuclear explosion at Hiroshima... (apparently the air pressure at detonation was 1million atmospheres) Unless we employ hand-wavium or simply say that the pod's velocity at impact is less than 12000kph...But then, what speed is it? And furthermore, how are our little marines going to survive the impact? The idea of inertial dampeners isn't too far out of scope, especially when you consider we have starships in orbit (in the WH40K-verse) that turn to new headings, engage in actions and perform actions that would seem to necessitate some sort of dampening. That and if you consider such rapid decleration from 12000kph down to (say) 200kph, then you still get an impact pressure of 4.2 E+03 GPa. Tim
|
|
|
Post by CELS on Apr 7, 2005 16:12:08 GMT -5
Let's get one thing straight. The fluff says that the drop pods use retro-rockets to slow their descent. This is, for me, beyond questioning. Simple fact. The only question is whether or not drop pods use additional methods.
Now, someone mentioned that the cockpit (?) of the Apollo moon rockets entered the atmosphere at far greater speed than the Astartes drop pods. While interesting, it's not quite comparable, since those cockpits released parachutes at high altitudes, and didn't really hit the ocean surface with extreme speed. At least, that's the impression I got from the Apollo 13 movie.
I think the first question we need to ask ourselves is whether or not rockets are enough to bring the Space Marines down alive. And I think we've made enough guesses without any kind of calculations. Does anyone here possess the skills in maths and physics to calculate how slow a drop pod must decelerate in order for the Marines to stay alive.
I think someone posted the weight and entry speed of the drop pod.
Who's up for the task? Eh? Eh? ;D
|
|
|
Post by Kage2020 on Apr 7, 2005 17:30:08 GMT -5
Retrorockets to slow descent (i.e. parachutes might be damaged if they were used), then parachute and then retro once more? No powerfields... Kage
|
|
|
Post by Sojourner on Apr 8, 2005 3:08:51 GMT -5
I've mentioned this before but I'll mention it again - coming from orbit gives enough kinetic energy that, if the Earth was hard vacuum without atmosphere, anything coming in from orbit would be travelling at 35 times the speed of sound when it hit the ground.
I'd ignore the bit about high speed to avoid air defences, personally. It's just not workable. These things have to slow down - retro engine for high reentry, and CG system for the final approach.
|
|
|
Post by Briareos on Apr 8, 2005 3:56:27 GMT -5
I'd ignore the bit about high speed to avoid air defences, personally. It's just not workable. These things have to slow down - retro engine for high reentry, and CG system for the final approach. It depends how you view the avoidance. I do not think pods could realistically be fast enough to avoid missiles or flak. But they could reach the ground quickly so as to not give the enemy forces the time to mobilise (part of) their air defences (fighter jets and such counter-measures). That would imply a time window of, what, 10-15 mn between orbit launch and the landing ? Hum... The more I dwell on this, the more I find drop pods deployment constraining and kluncky, tactically speaking. I don't really see the point of using them except for the psychological impact of crashing into enemy formations, or as scout deployment vehicles...
|
|
|
Post by Sojourner on Apr 8, 2005 4:42:46 GMT -5
The Apollo reentry module took about 4 minutes to pass through the magnetosphere, so that sounds reasonable. The stratosphere is much thicker IIRC.
|
|