Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Widewing on October 01, 2013, 10:24:19 PM
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(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn2/981182_521914391207014_1483717516_o.jpg)
Nope, no hiccups, no sneezing, no nothing. Better hope his insurer never sees this.
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ha or any rouge waves
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Dale "Snort" Snodgrass at the stick. Flew F-14s. The film Top Gun was loosely based on Snort. He's known for taking risks. However, he's had his share of brainfarts too. He landed the PoF F-86F wheels up.... Forgot to lower them. No longer gets to fly the F-86.....
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I saw him fly the F-86 in an airshow at Dobbins AFB some years ago. Beautiful airplane.
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No longer gets to fly the F-86.....
That super-sucks. :(
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I remember first seeing this pic floating around the net in the 90's:
(http://www.aerofiles.com/f14flyby.jpg)
The pilot was Capt Dale "Snort" Snodgrass, at the time Executive Officer of VF-33 with more than 4,800 hours in the F-14, currently Director of Congression- al Liasion, US House of Representatives.
The photo from the USS America in the summer of 1989 is widely seen, and most folks think it was either an edited photo, a risky maneuver, or a crash in progress. However, Snodgrass explained: "It's not risky at all with practice. It was my opening pass in a Tomcat tactical demonstration at sea. I started from the starboard rear quarter of the carrier, slightly below flight deck level. Airspeed was about 270 kts with the wings swept forward. I selected afterburner at about a half-mile out, and the aircraft accelerated to about 315 kts. As I approached the fantail, I rolled into an 85-degree bank and did a hard 5-6G turn, finishing about 10-20 degrees off of the boat's axis. Microseconds after this photo was taken, after rolling wings-level at an altitude slightly above the flight deck, I pulled vertical with a quarter-roll to the left, ending with an Immelman roll-out 90 degrees and continued with the remainder of the demo. It was a dramatic and, in my opinion, a very cool way to start a carrier demo as first performed by a great fighter pilot, Ed "Hunack" Andrews, who commanded VF-84 in 1980-1988.
The photo was taken by a Petty Officer who worked the flight deck. The individual with his arms behind his back was Admiral Jay Johnson, immediate past Chief of Naval Operations for the USN."
http://www.aerofiles.com/f14flyby.html (http://www.aerofiles.com/f14flyby.html)
:D
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I remember first seeing this pic floating around the net in the 90's:
(http://www.aerofiles.com/f14flyby.jpg)
The pilot was Capt Dale "Snort" Snodgrass, at the time Executive Officer of VF-33 with more than 4,800 hours in the F-14, currently Director of Congression- al Liasion, US House of Representatives.
The photo from the USS America in the summer of 1989 is widely seen, and most folks think it was either an edited photo, a risky maneuver, or a crash in progress. However, Snodgrass explained: "It's not risky at all with practice. It was my opening pass in a Tomcat tactical demonstration at sea. I started from the starboard rear quarter of the carrier, slightly below flight deck level. Airspeed was about 270 kts with the wings swept forward. I selected afterburner at about a half-mile out, and the aircraft accelerated to about 315 kts. As I approached the fantail, I rolled into an 85-degree bank and did a hard 5-6G turn, finishing about 10-20 degrees off of the boat's axis. Microseconds after this photo was taken, after rolling wings-level at an altitude slightly above the flight deck, I pulled vertical with a quarter-roll to the left, ending with an Immelman roll-out 90 degrees and continued with the remainder of the demo. It was a dramatic and, in my opinion, a very cool way to start a carrier demo as first performed by a great fighter pilot, Ed "Hunack" Andrews, who commanded VF-84 in 1980-1988.
The photo was taken by a Petty Officer who worked the flight deck. The individual with his arms behind his back was Admiral Jay Johnson, immediate past Chief of Naval Operations for the USN."
http://www.aerofiles.com/f14flyby.html (http://www.aerofiles.com/f14flyby.html)
:D
I love the narrative - BUT; there is no way the guy "with his arms crossed behind his back" in the photo is an Admiral. Anyone that has served Active or Reserve Service knows there is NO WAY a G/FO sits of the flight deck during operations
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I remember first seeing this pic floating around the net in the 90's:
(http://www.aerofiles.com/f14flyby.jpg)
The pilot was Capt Dale "Snort" Snodgrass, at the time Executive Officer of VF-33 with more than 4,800 hours in the F-14, currently Director of Congression- al Liasion, US House of Representatives.
The photo from the USS America in the summer of 1989 is widely seen, and most folks think it was either an edited photo, a risky maneuver, or a crash in progress. However, Snodgrass explained: "It's not risky at all with practice. It was my opening pass in a Tomcat tactical demonstration at sea. I started from the starboard rear quarter of the carrier, slightly below flight deck level. Airspeed was about 270 kts with the wings swept forward. I selected afterburner at about a half-mile out, and the aircraft accelerated to about 315 kts. As I approached the fantail, I rolled into an 85-degree bank and did a hard 5-6G turn, finishing about 10-20 degrees off of the boat's axis. Microseconds after this photo was taken, after rolling wings-level at an altitude slightly above the flight deck, I pulled vertical with a quarter-roll to the left, ending with an Immelman roll-out 90 degrees and continued with the remainder of the demo. It was a dramatic and, in my opinion, a very cool way to start a carrier demo as first performed by a great fighter pilot, Ed "Hunack" Andrews, who commanded VF-84 in 1980-1988.
The photo was taken by a Petty Officer who worked the flight deck. The individual with his arms behind his back was Admiral Jay Johnson, immediate past Chief of Naval Operations for the USN."
http://www.aerofiles.com/f14flyby.html (http://www.aerofiles.com/f14flyby.html)
:D
Snort is very much the self-promoter.... I doubt the guy in the LSO vest is anything but an LSO. I've never seen a Admiral on the flight deck unless he was coming or going from the ship (and I flew them on and off when they did).
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Snort is very much the self-promoter....
Based on the photographic and literal evidence, I figured as much. :D
I doubt the guy in the LSO vest is anything but an LSO. I've never seen a Admiral on the flight deck unless he was coming or going from the ship (and I flew them on and off when they did).
:)
...I doubt an F-14 rolls 90 degrees in microseconds either. :D
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Yeah, pic #1 is plumb stupid.
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There are only types of pilots, those who have forgotten to pull gear up, and those who will, one day.
Flew with a friend in a old Laker amphibious plane, landing on water in that machine, you do NOT want to land gear-up in water, forgetting it can be your next cold bath :angel:
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Don't you mean 'lower gear' and 'gear down?' :headscratch:
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That's the other other kind of pilot.
:joystick:
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He's in ground effect. Not sure how it effects the P-51D, but some planes have to be forced to lose altitude once in ground effect (B47 for example).
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(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn2/981182_521914391207014_1483717516_o.jpg)
Nope, no hiccups, no sneezing, no nothing. Better hope his insurer never sees this.
:airplane: :frown: There are two rules in aviation, which I think should enter into this topic: "There are old pilots and bold pilots, but no old, bold pilots"!
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Except Chuck Yeager, Bud Anderson, and a few others....
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He's in ground effect. Not sure how it effects the P-51D, but some planes have to be forced to lose altitude once in ground effect (B47 for example).
Not really an accurate statement. Ground effect reduces drag..with a clean airplane such as a B-47 you need to be right on speed wise to avoid a long float. Drag devices are your friend.
They have to be forced to slow down....then the going down is automatic.
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Ground effect increases lift. Air is literally reflected off the ground and back onto the wing. The only way it may decrease drag is by decreasing the angle of attack needed to maintain the required lift.
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Reflected off the ground? I don't understand what that means. I thought the big part of ground effect was that circulation is interrupted by the ground,(no wing tip vortices.)
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http://youtu.be/xr8N0Z4Cl0U?t=2m33s (http://youtu.be/xr8N0Z4Cl0U?t=2m33s)
Here is where I got my information.
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Here's a definition on wiki:
When an aircraft is flying at an altitude that is approximately at or below the same distance as the aircraft's wingspan or helicopter's rotor diameter, there is, depending on airfoil and aircraft design, an often noticeable ground effect. This is caused primarily by the ground interrupting the wingtip vortices and downwash behind the wing. When a wing is flown very close to the ground, wingtip vortices are unable to form effectively due to the obstruction of the ground. The result is lower induced drag, which increases the speed and lift of the aircraft.
Primary effect is a reduction in drag.
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Reflected off the ground? I don't understand what that means. I thought the big part of ground effect was that circulation is interrupted by the ground,(no wing tip vortices.)
:airplane: Don't want to disagree with anyone on this subject, but will tell of an experience I had one time in the B-29. One of the things about the "fowler" type flaps on the 29 is the ground effect is very noticeable on hot days, like down at McDill at Tampa in the summer time. We found that in order to shorten "float" time and roll out distance, just as we crossed the "numbers' and about 4 or 5 feet high, just bleed off about 10% and the old bird would settle right down on the runway. We had to go to Thule, Greenland on a training exercise one week, and on final approach, snow and ice on runway to some degree, but not totally covered, as we flared over the numbers, we didn't even have time to raise the flaps any as the bird set right down on the runway as soon as we reduced power all off.
Any paved runway is warmer than what I call normal and produces "heat" thermals, which affect ground effect on aircraft. In any cold weather climate which I flew in, seems as though we always touched down sooner than expected, so I would think the cool or cold runways doesn't produce as much ground effect, which makes me think the theory of small heat thermals affecting aircraft on landing might be the granddaddy of ground effect. I know that when you land on a grass or dirt runway, I have never noticed any ground effect.
Just bend over and look down a paved hi-way someday and you will see, even in winter time, small heat thermals rising from the surface.
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DaveBB I skimmed the video but couldn't find the part about reflections except in the graphic that showed the ground effect plane vs the hovercraft, can you tell me approximately where the explanation is in the video.
The graphic that I saw represented the wing trapping a cushion of air below it. I believe this only happens very very close to the surface and is not the cause of lift in an akranoplan.
I'm a little confused about the argument of lift vs drag in ground effect because they seem like two sides of the same coin. My understanding is that inhibiting circulation from the high pressure bottom of the wing to the low pressure top has the effect of virtually lengthening the wing span so that the wing can fly at a lower angle of attack for the same amount of lift thereby reducing the amount of drag for a given amount of lift. This is why they put those cool little winglets on airliners.
The way I understand ground effect vehicles is that they can only fly in ground effect because out of ground effect the wing has to be at the angle of attack at which it stalls.
I would say that a better way of thinking about the whole thing might be to describe a wing in ground effect as developing lift more efficiently than a wing out of ground effect. This means that there is more power available for acceleration and conversely that an airplane in ground effect does not slow down as fast as one out of it.
DaveBB I don't know if you have done much reading on aerodynamics so I apologize if I am stating the obvious but, most of the lift generated by a wing is done by the top of the wing not the bottom. This means among other things that you can hang all kinds of stuff below the wing and it still works really well.
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It starts at 2:35 and last for 30 seconds.
"The wing in ground effect occurs when an aircraft flies low and distance between the wing and land is small. The incoming air reflected by the wing hits the land and returns back. Thus, an additional lifting power appears. Such effect is most complete when the flight altitude is less than the wing's width."
The graphics literally show air being deflected by the wing, striking the ground, and bouncing back to the undersurface of the wing.
Also, why did you skim the video? I had it set to start at the presentation of the ground effect? Did it not start at 2:35?
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Video started at the beginning title sequence. Looked at the bit you just pointed out and while I'm not an aerodynamicist it doesn't make any sense to me from the reading on subsonic aerodynamics that I have done. I just looked at the Wikipedia page on the ekranoplan and the first paragraph of the article basically reiterates my understanding with the exception of a late reference to a "cushion of air" which seems to contradict the beginning.
The graphic and description in the video just seem like a bad intuitive guess on the part of the film producers, maybe they didn't have the money to make an animation complicated enough to explain what's going on.
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http://youtu.be/xr8N0Z4Cl0U?t=2m33s (http://youtu.be/xr8N0Z4Cl0U?t=2m33s)
Here is where I got my information.
:airplane: I am not sure if these guys who made this video know what they are talking about or not, but, Have you ever watched a wind tunnel test on a aircraft wing, using smoke trailers to record event? Sure doesn't look like the info in this video is supported by visual facts. Take a Cessna 172, high wing, and a Piper PA-28 Cherokee, low wing and I don't see where there are much difference, if any in touch down from power off, to impact with the runway! If they wing did in fact produce some sort of cushion of air, the PA-28 would float a lot longer on landings than a Cessna 172. They are both about the same weight, so that wouldn't have much effect if any. I still maintain that heat thermals, refected off the warm surface, is more responsible for ground effect. The amount of "float" in this game is not reflected in the RL.
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I don't know about the thermals but if you have an engine out and there is a ditch running through the field you've picked to land on, I can say with confidence that ground effect kicks into turbo mode.
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Thermals off the runway and ditches across a field are not ground effect. Here is a pretty good definition. (http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Ground_effect_in_aircraft.html)
The info that was in the video posted by davebb stated the effect was when within 1/2 chord width of the ground. That close to a surface I can see where you could get some "cushioning" effect. Practically you won't see that in aircraft because you just can't get that low. The drag reduction seen when in ground effect occurs within one wingspan and is most pronounced within 1/2 wingspan of the surface.
Mooney aircraft have a reputation for floating on landing. It is a clean design, low wing with short gear legs, it may be one airplane that can get within 1/2 chord width from the surface.
Along with floating on landing another place you can get into trouble if you don't understand ground effect is taking off, especially when hot/high. Due to the decreased drag the aircraft may be able to lift off but is then unable to climb out of ground effect due to decreased performance from the density altitude.
Ground effect can be useful for getting off a short/soft field (without significant obstacles) because you can get in the air when very slow, then accelerate while in ground effect before starting a normal climb. I've done this off gravel/sand bars -- flaps up as you begin roll to limit drag, pop FULL flaps and rotate when speed is right (on my 182 that was usually just when the airspeed indicator started to wiggle, well below normal book numbers). Airplane comes off the ground, you don't try to climb you just fly along easing the flaps up and letting the airplane to accelerate to climb speed.
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This is linked to 2:35 into the video it explains the ground effect quite well. I recommend watching the entire video. This series is truly excellent.
http://www.youtube.com/watch?v=xr8N0Z4Cl0U&t=2m35s
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I think there is confusion about what is meant by "ground effect". If we are talking about aeroplanes it is mainly the reduction of induced drag. If we are talking about ground effect vehicles then we are probably talking about stagnation of air under the vehicle providing a high pressure cushion. I still don't think the reflections in the video are plausible.
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I think there is confusion about what is meant by "ground effect". If we are talking about aeroplanes it is mainly the reduction of induced drag. If we are talking about ground effect vehicles then we are probably talking about stagnation of air under the vehicle providing a high pressure cushion. I still don't think the reflections in the video are plausible.
:airplane: I know there is a lot scientific information posted here and on u-tube, but, Go to Crystal River, Fla, which has 2 runways, 1 grass and 1 paved. Wait until late in day, with not enough wind to make any difference and land on the grass runway and then on the paved runway. First thing you will notice is how much longer, after all power off, the aircraft will float down the runway on paved surface than it does on grass.
Now if all the explanations of ground effect were accurate, there would be no difference in the paved and unpaved runway, but there is a difference, so I am going to stick with reflected heat or thermals from paved surface, vs unpaved surface as the cause of so called ground effect. At any rate, not flying anything heavy anymore, I don't have to worry about "ground effect" anymore.
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For ground effect , look up the Blackburn Buccaneer . That plane could be flown hands free at 25ft from the ground and never nose down into the ground due to ground effect . An extremely stable bomber / attack aircraft that flew from the 1960's to the mid 1990's with the RAF and NFAA .
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For ground effect , look up the Blackburn Buccaneer . That plane could be flown hands free at 25ft from the ground and never nose down into the ground due to ground effect . An extremely stable bomber / attack aircraft that flew from the 1960's to the mid 1990's with the RAF and NFAA .
:airplane: I don't doubt your comment about the hands off at 25 feet, but that is not low enough to be in ground effect! By that logic, a B-36 peace maker, with a 230 foot wing span, could encounter ground effect somewhere around 75 feet. Someone, somewhere, computed the height above ground level to be in ground effect, based on the length of the wing! I can't find it right now, but will cont' looking. Again, I personally don't think that is accurate for a number of reasons, I still say that so called ground effect is based on heat thermals from the runway. Again, I invite anyone to land on pavement, then turn around and land, same direction, in the grass! You are going to see there is a difference. When this thread started, I was curious, so I called a friend of mine, J. Wingo, a 20 year veteran in the outback of Northern Canada, who flies a Maule, hauling hunters and fisherman into the outback. He says that he carries power, just above a stall when landing on a sand bar, chops throttle just as he gets over dry land and it lands immediately. So if there was such a thing as true ground effect, why wouldn't the Maule float a few feet prior to touching down. He is an old timer and says that is hog wash! Jay married my sister-in-laws, sisters, daughter.
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ET, heated air rising off the runway isn't ground effect. Granted that it will cause you to float....it's rising air....same as hitting a thermal.
Ground effect has the most effect within 1/2 wingspan of the surface.
Your buddy is dragging in using power, of course it lands when he pulls the power off. It doesn't float because he is nailing the approach speed. If he really wants to test it tell him to go out a fly down the runway as slowly as he possibly can just inches above the surface and have him take note of the amount of power needed to maintain level flight at that speed. Then tell him to do the same thing more than a wingspan above the ground. If it is a measurable amount he'll note that it takes a bit less power to make that super low pass than it does for the higher pass due to the reduced drag resulting from ground effect.
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ET, heated air rising off the runway isn't ground effect. Granted that it will cause you to float....it's rising air....same as hitting a thermal.
Ground effect has the most effect within 1/2 wingspan of the surface.
Your buddy is dragging in using power, of course it lands when he pulls the power off. It doesn't float because he is nailing the approach speed. If he really wants to test it tell him to go out a fly down the runway as slowly as he possibly can just inches above the surface and have him take note of the amount of power needed to maintain level flight at that speed. Then tell him to do the same thing more than a wingspan above the ground. If it is a measurable amount he'll note that it takes a bit less power to make that super low pass than it does for the higher pass due to the reduced drag resulting from ground effect.
:airplane: Hey friend, you and I don't need to debate this, because you can't convince me or a lot of other pilots in this world that ground effect exists! Take your aircraft, land on grass and then pavement, should be the same, right? There are just some things about aviation that the so called experts have never really pinned down. All these explanations that you and some others are reading are theories, yet to be proved.
Just like some say the reason the aircraft turns is the high wing produces more lift that the low wing, hence it turns. Wind tunnel tests have shown time and time again that the whole wing is producing "resultant" lift, my term, and lift is what pulls the aircraft around in the turn. If you are slipping or skidding in the turn, yes, one wing will produce more lift than the other one, but if it is a level, constant altitude turn, both wings are producing the same amount of lift. Think about it, if it was true about the high wing producing more lift, the aircraft would just cont' on until inverted. Now, you and I both know that a lot of aircraft can be set up into a turn and with out touching anything, will cont' that bank angle and turn, unless some outside force acts on it, i.e., controls, wind, surface turbulence. If you turned it loose during the turn, it would start to continue banking until inverted. Don't mean to be stubborn, but until someone can show me some facts, gonna stay with what I have learned in 66 years of flying with no accidents!
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Ground effect doesn't exist but being "on the step" does?
I've flown plenty from grass runways and I've never noticed the phenomenon you're talking about. If anything I've floated a little more in the grass surfaces for want of a slightly smoother touchdown whereas if I need to plant it on pavement I'm not worried about turf because I'm going to have a pretty uniform surface I'm not going to compress with an airplane.
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Ground effect doesn't exist but being "on the step" does?
I've flown plenty from grass runways and I've never noticed the phenomenon you're talking about. If anything I've floated a little more in the grass surfaces for want of a slightly smoother touchdown whereas if I need to plant it on pavement I'm not worried about turf because I'm going to have a pretty uniform surface I'm not going to compress with an airplane.
:airplane: Being "on step" is not some theory. All getting an aircraft on step, as it is called, is exceeding the normal cruise speed by a few knots and is usually accomplished by climbing slightly higher than intended cruising altitude, set up a slight descending attitude until back down to the altitude you intend to cruise at. What you are actually doing by doing this step, is changing slightly the AOA during cruise, the desired AOA is slightly a negative AOA. But, as with a lot of other things in aerodynamics of flight, there are outside factors which will effect "step", such as into the wind, down wind, turbulence, snow, rain, ice pellets, so the conditions have to be right to actually attain "on step" and maintain "on step". Now, basically we are talking about aircraft without a "flight director", as with those aircraft, if you dial up 250knots, that's what it is going to fly at. The aircraft which we are talking about are manually flown aircraft. Now that is not to say that a aircraft with a auto pilot, which has a altitude hold feature, cannot be set up "on step" because it can, you just have to engage said auto pilot feature after you obtain the on step speed for that aircraft. But, again, there are several outside factors which can disturb the on step speed. The old Beechcraft Bonanza, with a "V' tail confg is a good example. It is easy to get on step, but first turbulence and the thing starts "fish tailing" and your step advantage goes away.
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When grond effect does not exist, how do ground effect vehicles work? :old:
(http://upload.wikimedia.org/wikipedia/en/5/5f/Lun_Ekranoplan.jpg)
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When grond effect does not exist, how do ground effect vehicles work? :old:
(http://upload.wikimedia.org/wikipedia/en/5/5f/Lun_Ekranoplan.jpg)
:airplane: That, sir is a whole different concept in which the aircraft works! Its producing power to hold it above the ground and so called ground effect. With out equipment and engines to provide downward thrust, it would depend on forward speed to maintain that low of altitude. The bottom line is just this: as long as lift overcomes gravity, it will stay in the air, but with no thrust to provide forward speed to develop lift, then weight overcomes gravity and down she comes. That is another reason I keep saying "ground effect" is an old timers tale. Once forward speed, which is producing the lift of the wing, is reduced to the point of weight, i.e., gravity, overcoming the lift factor, the aircraft is going to land or crash, depending on where you are when you run out of airspeed and altitude at the same time.
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:airplane: That, sir is a whole different concept in which the aircraft works! Its producing power to hold it above the ground and so called ground effect. With out equipment and engines to provide downward thrust, it would depend on forward speed to maintain that low of altitude.
What downward thrust? For example the Lun depicted above has no other thrusters than the 8 forward mounted, conventional turbojets
The A-90
(http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/A-90_Orlyonok_4.JPG/800px-A-90_Orlyonok_4.JPG)
has two PAR turbofans vectoring their thrust below the wings for takeoff, but are shut down after that and the Ekranoplan is only flying in ground effect, driven by it's huge turboprop. No additional downward thrust at all.
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:airplane: Being "on step" is not some theory. All getting an aircraft on step, as it is called, is exceeding the normal cruise speed by a few knots and is usually accomplished by climbing slightly higher than intended cruising altitude, set up a slight descending attitude until back down to the altitude you intend to cruise at. What you are actually doing by doing this step, is changing slightly the AOA during cruise, the desired AOA is slightly a negative AOA. But, as with a lot of other things in aerodynamics of flight, there are outside factors which will effect "step", such as into the wind, down wind, turbulence, snow, rain, ice pellets, so the conditions have to be right to actually attain "on step" and maintain "on step". Now, basically we are talking about aircraft without a "flight director", as with those aircraft, if you dial up 250knots, that's what it is going to fly at. The aircraft which we are talking about are manually flown aircraft. Now that is not to say that a aircraft with a auto pilot, which has a altitude hold feature, cannot be set up "on step" because it can, you just have to engage said auto pilot feature after you obtain the on step speed for that aircraft. But, again, there are several outside factors which can disturb the on step speed. The old Beechcraft Bonanza, with a "V' tail confg is a good example. It is easy to get on step, but first turbulence and the thing starts "fish tailing" and your step advantage goes away.
Not buying. Are you aware of the dangers of the downwind turn as well?
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Not buying. Are you aware of the dangers of the downwind turn as well?
:airplane: Depends on your airspeed where or not the down wind turn is of any danger to the aircraft!
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What downward thrust? For example the Lun depicted above has no other thrusters than the 8 forward mounted, conventional turbojets
The A-90
(http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/A-90_Orlyonok_4.JPG/800px-A-90_Orlyonok_4.JPG)
has two PAR turbofans vectoring their thrust below the wings for takeoff, but are shut down after that and the Ekranoplan is only flying in ground effect, driven by it's huge turboprop. No additional downward thrust at all.
:airplane: But it is producing enough thrust to over come weight, i.e., gravity, so there fore it will fly, as long as lift equals drag and weight sir!
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For a non-aviator such as myself, let's see if I understand this right. Vortices are produced by the wing. These create drag by some mechanism (are they creating low pressure areas behind the wing, actually try to pull the wing in the opposite direction of flight?). When low to the ground, these vortices can't form, and by whatever mechanism that they use to normally create drag cannot occur?
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For a non-aviator such as myself, let's see if I understand this right. Vortices are produced by the wing. These create drag by some mechanism (are they creating low pressure areas behind the wing, actually try to pull the wing in the opposite direction of flight?). When low to the ground, these vortices can't form, and by whatever mechanism that they use to normally create drag cannot occur?
:airplane: Vortices's are created by the Wing Tips, primarily by the shape of the wing tip. Some aircraft produce more vortices's than others and the heavy the aircraft, the more pronounced vortices's are present. The vortices's are what creates the "wake" turbulence and have been responsible for several accidents. Vortices's are no problem on landing, if you plan your touch down beyond where the aircraft in front of you touched down. It is best practice to wait on takeoff for a couple or 3 minutes to give the vortices's time to dissipate or the wind move them to the side of the runway prior to you taking off. In FAA tests of vortices's, they settle behind the generating aircraft and as long as you climb above the aircraft in front of you, you shouldn't encounter any problem. Don't let ATC rush you into to taking off, until you are satisfied that wake turbulence will be no problem to you.
Vortices's per sae do not produce any drag, that is created by the shape of the wing itself. Any wing which produces lift, also produces drag, but again, the shape of the wing will dictate how much drag is created.
For example, in this game, the B-17G has a "Hersey Bar" type wing, which is designed to create a lot of lift, but it also creates a lot of drag, hence the reason for slow speed of the aircraft in all flight realms. In the other end of the spectrum, look at the LA-7 wing, which is designed for speed and because of the shape does not produce much drag.
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Why do most modern airplanes have winglets?
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Why do most modern airplanes have winglets?
As the wing cuts through the air, the air at the tip of the wing will curl over the wingtip and on to the top of the wing. This creates some drag. It also creates a vortex coming off the wingtip, which trails behind the plane. The winglet guides the air up and away from the tip of the wing, and diminishes the effect.
Wikipedia is not an authoritative source, but this page does explain it well, and has good illustrations:
http://en.wikipedia.org/wiki/Wingtip_device (http://en.wikipedia.org/wiki/Wingtip_device)
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The question is for earl regarding this post:
:airplane: Vortices's are created by the Wing Tips, primarily by the shape of the wing tip. Some aircraft produce more vortices's than others and the heavy the aircraft, the more pronounced vortices's are present. The vortices's are what creates the "wake" turbulence and have been responsible for several accidents. Vortices's are no problem on landing, if you plan your touch down beyond where the aircraft in front of you touched down. It is best practice to wait on takeoff for a couple or 3 minutes to give the vortices's time to dissipate or the wind move them to the side of the runway prior to you taking off. In FAA tests of vortices's, they settle behind the generating aircraft and as long as you climb above the aircraft in front of you, you shouldn't encounter any problem. Don't let ATC rush you into to taking off, until you are satisfied that wake turbulence will be no problem to you.
Vortices's per sae do not produce any drag, that is created by the shape of the wing itself. Any wing which produces lift, also produces drag, but again, the shape of the wing will dictate how much drag is created.
For example, in this game, the B-17G has a "Hersey Bar" type wing, which is designed to create a lot of lift, but it also creates a lot of drag, hence the reason for slow speed of the aircraft in all flight realms. In the other end of the spectrum, look at the LA-7 wing, which is designed for speed and because of the shape does not produce much drag.
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The question is for earl regarding this post:
:airplane: Not being a trained aeronautical engineer, I have to rely on the experts to evaluate the affective's of winglets and Horner tips. Southwest Airlines claims to be able to save 10 million galleons of jet fuel over a 5 year period because of the installation of "winglets" on their Boeing 737's. That seems to be the biggest advantage to them, as well as better low speed handling because of increased air flow over the aileron area and in proves lift over the whole wing. A French scientist named Burnelli, I think his name is spelled correctly, is credit with the discovery of the "venture" effect of compressing air over an area, increasing speed and there fore, a low pressure area, (lift). The Burnelli effect has had a huge influence on wing design and has certainly had a huge impact on a number of designs.
The Burnelli effect even had an effect on carburetor design, with a venture being the center piece of float type carburetors, which were first used in early aircraft, such as the Spit 1, which we have here in this game. That is the main reason for carburetor heat in internal combustion engines, as the increased airflow down through the carburetor produces increased airflow through the throat of the carburetor, but also produces a rapid drop in atmospheric pressure, which results in a rapid decrease in temperature, creating "ice" in the carburetor and choking off the air flow through the carburetor.
The U.S Air Force for years have studied their Boeing KC-135's and other aircraft with the winglet's installed and have concluded that they contribute to fuel range and a causal increase in lift to drag ratio.
There is a lot more to this subject and I would be the last one to rely on for the last word in winglets. I have never flown anything with winglets, although a club I used to instruct in, had a Cessna 210 with Horner tips.
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ET I have the utmost respect for you and your aviation experience. I have to wonder if maybe we're arguing semantics. However you're making some errors in this discussion about ground effect. I don't say this because I think so, but because all the teaching I've had over the years, everything I've read over the years and the FAA don't agree with you about this. Ground effect is "only a theory" as much as lift, weight, thrust and drag are "only a theory".
You and I can agree to disagree and move on. <S>
For anyone who wants to read more about ground effect here is a link to a PDF taken from the FAA Pilots Handbook of Aeronautical Knowledge. (http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf) Scroll down to page 4-9 for the discussion on ground effect which starts with:
It is possible to fly an aircraft just clear of the ground (or water) at a slightly slower airspeed than that required to sustain level flight at higher altitudes. This is the result of a phenomenon better known of than understood even by some experienced pilots. When an aircraft in flight comes within several feet of the surface, ground or water, a change occurs in the three- dimensional flow pattern around the aircraft because the vertical component of the airflow around the wing is restricted by the surface. This alters the wing’s upwash, downwash, and wingtip vortices. [Figure 4-13] Ground effect, then, is due to the interference of the ground (or water) surface with the airflow patterns about the aircraft in flight.
:salute
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ET I have the utmost respect for you and your aviation experience. I have to wonder if maybe we're arguing semantics. However you're making some errors in this discussion about ground effect. I don't say this because I think so, but because all the teaching I've had over the years, everything I've read over the years and the FAA don't agree with you about this. Ground effect is "only a theory" as much as lift, weight, thrust and drag are "only a theory".
You and I can agree to disagree and move on. <S>
For anyone who wants to read more about ground effect here is a link to a PDF taken from the FAA Pilots Handbook of Aeronautical Knowledge. (http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf) Scroll down to page 4-9 for the discussion on ground effect which starts with:
:salute
:airplane: No problem sir! This forum would be a dull place to visit if we all agreed on everything! I :salute the FAA for describing as best it can about the "phenomenon" known as ground effect, but, remember, these are the same folks who said that it was no longer necessary to teach primary students, "spin recovery tech's", nor was it necessary to make airliner cockpit doors inaccessible so passengers could not enter the cockpit area if not authorized and we both know the results of those two decisions. If you don't mind, I will cont' to keep "ground effect" in the same category as UFO's, Big Foot, high wing producing more lift than the low wing, which turns the a/c and last, but not least, Reptileman in Fla. They say a alligator and a good looking blonde headed woman had a relationship and there are blonde headed, dark eyed men walking around in the Everglades. I guess that is another thing on my bucket list which will be one of those things I will miss!
AT any rate, when you review their comments, the FAA, notice they don't say anything about grass, just water and pavement! In my view, if it really worked, the effect would be the same on all three surfaces. You know all aviation aircraft started out on grass and then progressed to paved runways. Funny how this subject was never mentioned prior to paved runways!