Your next bug hive..., Eek! |
Your next bug hive..., Eek! |
Jul 26 2006, 05:58 PM
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#1
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Shooting Target Group: Validating Posts: 1,618 Joined: 29-January 03 From: Montevideo, Uruguay. Member No.: 3,992 |
... could be a 526 mts. deep Siberian diamond mine. :eek:
Warning: That picture is safe, but the rest of the website seems loaded with spyware. |
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Jul 26 2006, 06:24 PM
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#2
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Chrome to the Core Group: Dumpshocked Posts: 3,152 Joined: 14-October 03 From: ::1 Member No.: 5,715 |
Getting used in a future SR game. I swear it.
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Jul 26 2006, 07:51 PM
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#3
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Neophyte Runner Group: Members Posts: 2,174 Joined: 13-May 04 From: UCAS Member No.: 6,327 |
Aye, it's a nice picture to use as a prop for the group to see. Hmmm...
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Jul 26 2006, 08:04 PM
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#4
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Moving Target Group: Members Posts: 749 Joined: 28-July 05 Member No.: 7,526 |
wow... good find. reminds me of a thermal borehole from Alpha Centauri.
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Jul 27 2006, 04:47 PM
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#5
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It's for winners Group: Dumpshocked Posts: 523 Joined: 8-February 05 From: Wiltshire with da shooty stuff Member No.: 7,067 |
AWSOM! :)
Torzx |
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Jul 27 2006, 05:09 PM
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#6
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Shooting Target Group: Validating Posts: 1,618 Joined: 29-January 03 From: Montevideo, Uruguay. Member No.: 3,992 |
Apparently, winds are so strong that helicopters are sucked in.
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Jul 27 2006, 05:14 PM
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#7
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Chrome to the Core Group: Dumpshocked Posts: 3,152 Joined: 14-October 03 From: ::1 Member No.: 5,715 |
[Neo]Whoa.[/Neo]
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Jul 27 2006, 05:26 PM
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#8
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panda! Group: Members Posts: 10,331 Joined: 8-March 02 From: north of central europe Member No.: 2,242 |
it may be a "old" game, but oh how i love playing it :D could be something about the political and cultural humor hidden all over the game ;) and thats one hell of a strip mine :eek: |
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Jul 27 2006, 07:06 PM
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#9
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It's for winners Group: Dumpshocked Posts: 523 Joined: 8-February 05 From: Wiltshire with da shooty stuff Member No.: 7,067 |
Your joking? right? torzx |
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Jul 27 2006, 09:22 PM
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#10
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Target Group: Members Posts: 10 Joined: 27-July 06 Member No.: 8,971 |
I shake in my boots at the thought of going in there already.
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Jul 28 2006, 05:27 AM
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#11
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Shooting Target Group: Validating Posts: 1,618 Joined: 29-January 03 From: Montevideo, Uruguay. Member No.: 3,992 |
Here's what I found:
And...
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Aug 2 2006, 12:41 AM
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#12
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Moving Target Group: Members Posts: 903 Joined: 7-February 03 Member No.: 4,025 |
I'm not sure that I buy that. The further you go down a hole, the higher the air pressure, because of the weight of all the air on top of it. If the bottom of the pit is colder, the air would be a little denser still, but stable, with nothing to move it around, and no where to go.
Now if you go deep enough, you have geothermal effects, and the air at the bottom of the shaft would want to rise. Then you'd get currents in and out of the place, as warmer air rose out and more air would move in to replace it. I don't know how strong that would be. In addition, any wing, including the rotary wing of a helicopter, works on the principle of every action having an equal and opposite reaction. Rotor puts pressure on air, therefore air puts pressure on rotor, creating lift. It doesn't matter how far the air goes or what it hits afterwards. Ground effect is an exception, because air pressure builds up underneath the wing. Helicopters can't fly at high altitudes because of the thin air, but I don't see why the air just above the hole would be any thinner than the surrounding countryside. In other words, the surrounding air pressure is what determines an aircraft's performance, and that has little to do with the aircraft's altitude above ground level. The only thing that I can't visualize is the effect of changes in weather. If a high-pressure system moves in, you'd get wind into the hole. A low pressure system, and wind out. Don't know how strong they'd be, but probably not very. Lastly, if you have winds strong enough to suck a helicopter in, you'd have a damn hard time moving anything else in or out. Anyway, as a pilot, I'd probably not take the chance until I've actually seen the place. |
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Aug 2 2006, 02:45 AM
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#13
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
Any force period works on that principle. It's kinda implied.
Simplistic. The rotor forces air down, therefore the air forces the rotor up. Typically there's a tilt too so that the vehicle moves horizontally.
Ground effect is not an exception. If the air hits something, it'll bounce off that thing. If it hits a lot of irregularly-shaped things, it'll create irregular air movement (turbulence).
Hardly. Airspeed matters a great deal. If air is moving down, it's difficult to force that air even more down enough to maintain elevation. If air is moving up, it's easy to force enough air down to even move upwards. If air is moving too quickly in one direction or another, it can match the speed of the retreating blade and cause a complete loss of lift from that area (retreating blade stall). Surrounding air pressure is exactly one of many.
See above. If you take the supports out from under something, it tends to fall pretty easily. You'd need strong winds, but I think you're overestimating how strong.
Do you have any helicopter-flying experience? With all due respect, it is very little like flying a plane. ~J |
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Aug 2 2006, 04:12 AM
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#14
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Moving Target Group: Members Posts: 903 Joined: 7-February 03 Member No.: 4,025 |
Well, what I saw in the quotes looked like two arguments. In one, the guy seemed to have the impression that air pressure above the hole would be different than the area around it. I don't see any reason to think that. Secondly, the idea was presented that there would be constant movement of air into the hole. This I see potentially happening, but I don't think the argument made for it is sound. It looks to me like the guy's just suggesting that air will move into the hole because it's a hole.
Your responses to my statements are valid, but I don't see what they have to do with the debate at hand. Of course they're simplistic; I didn't see any need to point out that wings lift up, or to get nit-picky about how ground effect works. (Assumption on my part; I thought the explanation was enough for the point I was making.) Maybe I can clarify where I was going with it: Just because ground effect indicates that being closer to the ground creates more lift, doesn't prove that the opposite is true. So if I'm cruising along at 200' AGL, then the ground drops out beneath me as I pass over a giant ant nest, and suddenly I'm at 1200' AGL or 12000' AGL. I haven't lost any lift, so long as the air pressure hasn't changed. I don't think it would change much, because my altitude ASL hasn't changed. You're right that the aircraft will move relative to the ground if the air is moving. Obviously, if there's a wind, it'll push the aircraft around some. But then you'd still have to convince me that there's a lot of air moving into or out of the hole with more speed that a pilot can compensate for. That'd have to be some bitchin' thermals. Like I said, I doubt it, but I wouldn't bet my life on it. Never flown anything other than a Cessna 172 and a couple of gliders. Physics seems the same to me. You? (P.S. Why? Do you think the alleged giant hole air currents would affect one type of aircraft and not another?) Anyway, don't mean to argue, Kagetenshi. Maybe I didn't explain myself thoroughly enough for someone who knows their flying. Do you agree with the reasoning behind JongWK's sources? I'd like to know your take on whether or not a passing helicopter would be sucked into the giant bug hole. |
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Aug 2 2006, 04:29 AM
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#15
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
I'm just argumentative tonight, comes from sources unrelated to Dumpshock. It'll pass. I don't think I meant to imply that you thought your explanations were complete, but things needed to be clarified for the audience.
More when I'm awake, hopefully. ~J the brain-dead |
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Aug 2 2006, 11:59 AM
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#16
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Moving Target Group: Members Posts: 903 Joined: 7-February 03 Member No.: 4,025 |
You and I both, I suppose. No worries, bud.
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Aug 2 2006, 12:50 PM
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#17
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
Yeah, we don't have enough information to judge how much air movement there is--in particular, we'd need to know things like other openings to the system. That said, if the hole is fairly deep, the air temperature inside is going to be in the mid-50s F--during a decent amount of the year (winter, basically), that's going to result in cave air floating out into the atmosphere and atmospheric air sinking into the cave. That's not going to produce a directed airflow without a second opening (minimum--there would probably also need to be some cave structure encouraging cave air to leave through only one of the openings), but it is going to create moving air above the cave, and moving air has lower pressure than still air. How strong this effect is going to be, I don't know.
True as far as it goes. The problem is that changes in elevation are frequently associated with winds. The change in relative elevation and only relative elevation won't affect flight, but that variable doesn't usually change in isolation.
The issue for a helicopter is that the only momentum they get is caused by forcing air downwards. Airplanes get to force air downwards with the wings and force air (or hot exhaust) backwards. This would leave helicopters more vulnerable to downward-directed airflow--how much more vulnerable I don't know, but there is an additional area of risk there.
Nothing but simulations (if good ones--XPlane, mostly), but after discovering that most of my attempts to fly the simulated helicopter resulted in my being upside-down for most of the short trip to the ground, I spent some time researching what goes into flying a helicopter. Even under good conditions, they're touchy things to fly.
And here we come down to it :) the problem is that JongWK's sources don't have any reasoning per se--at least no second-level reasoning. Based on the assumption that there is a moderately strong airflow into the hole, however, I do consider it reasonable that a helicopter could get sucked in, and I also find it reasonable to believe that there's some degree of airflow into the hole some of the time. Whether or not there's enough airflow to do it, I can't guess. ~J |
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Aug 2 2006, 01:33 PM
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#18
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Running Target Group: Members Posts: 1,379 Joined: 16-April 02 From: the LI shadows Member No.: 2,607 |
Looks more like the entrance to Hell if you ask me.
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Aug 2 2006, 04:04 PM
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#19
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Running Target Group: Members Posts: 1,408 Joined: 31-January 04 From: Reston VA, USA Member No.: 6,046 |
I have no flying background of any kind, so this is pretty much spouting off in ignorance, but several of you have mentioned the difference that ground effects make in the lift that the helicopter can get. If a chopper was flying low enough for ground effects to provide extra lift, and then the ground effects were suddenly taken away (by taking away the ground...) I'd imagine that could make it tougher to control, and you'd have a greater likelihood of failling into the hole. Is this reasonable?
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Aug 2 2006, 04:17 PM
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#20
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
That's definitely reasonable, but as far as I can tell ground effect is mostly meaningful for helicopters when you're half the rotor diameter or less above the ground—not typical operating conditions, certainly.
Edit: "Ground effect typically does not exist when a plane operates more than one wingspan above the surface." (source) ~J |
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Aug 3 2006, 05:02 PM
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#21
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Moving Target Group: Members Posts: 903 Joined: 7-February 03 Member No.: 4,025 |
Yeah, you gotta be really low. Ground effect gives you some added lift, is the jist of it.
(I was taught a technique for using ground effect on rough field take offs. Say you want to save some wear and tear on your gear. You gun the throttle and cruise down the runway, then pop the plane up just a few feet at just the right speed. You're cruising above the crappy runway in ground effect, but you still have to accellerate some before you're fast enough to slip the surly bonds of earth, as it were.) So, if you're cruising a few feet over the ground at low speed, and the ground drops out from under you, then yeah, you'd likely fall. |
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Aug 3 2006, 07:19 PM
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#22
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Moving Target Group: Members Posts: 314 Joined: 25-February 06 Member No.: 8,307 |
Ummm, helicopters don't push air down to fly.
The rotors are small wings, and create a low-pressure area over the helicopter, which lifts the helicopter. A hole like that would create a downdraft, which reduces the lift the rotors can generate. If there's that much of a change in pressure, then it will likely cause wind shear, which will frag with fixed-wing aircraft as they fly over the edges. Ground effect does not affect helicopters as much as fixed-wings, and ground effect craft have specially designed "wings" and won't fly very high. Just thought I'd share some... |
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Aug 3 2006, 07:29 PM
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#23
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
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Aug 3 2006, 07:56 PM
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#24
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Moving Target Group: Members Posts: 314 Joined: 25-February 06 Member No.: 8,307 |
I stand corrected... And I learned that in my solo classes from Air Force pilots...
Not that I didn't believe you :wink: but I looked and found this: Helicopters fly by sucking air from above and forcing it downwards with a thrust equal to (for hovering) or exceeding (for climbing) the weight of the helicopter. |
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