will it take off?

[RobS]

Ground effect sturgeon fishing platform [Sea Monster] as seen on the Caspian sea.

And from that picture Egon, one can clearly see that the rearward velocity of the water is preventing the necessary lift to cause the plane to take off. It's practically sitting still (at least on my uncalibrated monitor).

Cool plane, weapons on the top?

 

[patrick_g]

Ground effect sturgeon fishing platform [Sea Monster] as seen on the Caspian sea.

Yeah, right! Sea monster &*($%# ^(*&%

They "fly" these things over flat land too. Can't get up out of ground effect to get over much of a hill or obstruction so you need to have a good map with radio towers and such located.

The Russians use these things to cross parts of their enormous land mass like we use trains and trucks.

Pat

 

[patrick_g]

And from that picture Egon, one can clearly see that the rearward velocity of the water is preventing the necessary lift to cause the plane to take off. It's practically sitting still (at least on my uncalibrated monitor).

Cool plane, weapons on the top?

Uh, technically not an airplane.

It can't get out of ground effect and go higher. It just scoots along in ground effect. It is a cargo hauler. Due to ground effect they are pretty efficient and fuel economical. This one at the Caspian is intended to land and take off from the water. They have land based versions as well.

No, those aren't weapons.

This baby IS too large to put into Eddies pond.

Pat

 

[Iplayfarmer]

I think you need to read it again. You were doing pretty much OK till you said the part I left quoted above.

Ground effect DOES NOT require the aircraft to be overloaded before it happens. Ground effect will, in fact, reduce the likelihood of a stall, provided you don't mind flying along within a couple wingspans of the ground. Ground effect so reduces drag and enhances lift that the near stall that is induced to make a good power off landing is prevented and instead of settling in nicely the plane (catches a balloon) just floats down the runway as if being held aloft by a tractor beam (not related to THAT kind of tractor.)

One of the dangerous down sides of ground effect is that it will tend to "trap" an overloaded aircraft at takeoff at a low altitude (within a couple wingspans of the ground) by providing extra lift and reduced drag ONLY when the A/C is close to the ground. The unlucky pilot of the overloaded plane can't get above ground effect, not because it holds him back or down but because it is what got him up there and without more lift than the pane can muster in "free air" the extra weight can't be lifted.

There is nothing wrong with using ground effect for beneficial purposes so long as you don't let it get you into trouble. The Russians have huge ground effect cargo carriers that operate like an aircraft but can't get above ground effect. They are very efficient but fly quite low. There are also recreational flying boats that don't get out of ground effect and do not require a pilots lisc.

Ground effect is interesting but NOT INVOLVED in our amphibious plane vs the retarding current experiment since in order to be in ground effect you need to be airborne and that requires sufficient airspeed to lift off which is not provided by the water current.

I do second your comment re the fish and in their behalf I suggest a weir would be needed to keep the fish out of the intake zone of the impeller. Since the inrush current is much more diffuse than the output current the weir (fish protective strainer) will not have to be very far from the impeller making it easier to construct, position, and pay for.

Pat

I was just paraphrasing this exerpt from the wikipedia site...

"'Wing in ground effect' during take-off is thought to be a cause of many aircraft accidents. A small plane loaded beyond gross weight capabilities may be able to take off under ground effect, thanks to the 'artificially' low stall speed due to the decreased induced drag. But it may not be able to climb beyond a certain point. Once the pilot climbs out of ground effect wingtip vortices will form, the wings will stall, and the aircraft will suddenly descend - usually resulting in a crash."

It sounds like the overloaded plane actually can get a little altitude since it takes a few seconds for the vortices to form.

 

[jimmysisson]

If Eddie only had flying fish, they could go airborne and lower the level a tad and increase the air cushion above the magic water. Keeping them up may be problematic...
Jim

 

[patrick_g]

It sounds like the overloaded plane actually can get a little altitude since it takes a few seconds for the vortices to form.

I can say that I have been in ground effect many many times and never came close to having it lead me anywhere near a stall.

I'm not saying it isn't possible or that on-line user contributions to encyclopedias are ever less than perfect, just that in quite a variety of aircraft and simulators I have been in and out of ground effect many many times and never had that experience. I'll accept that it is possible and that my limited experience mislead me.

Pat

 

[Egon]

Ground effect?? I have experienced it many a time on both
skis and bicycles. At no time was the end result pleasant as the flying body came to an abrupt halt on less than feather soft conditions.

Now flying fish, did not Thor Heyerdahl and his Kontikki companions breakfast on them on a regular basis??

 

[patrick_g]

Now flying fish, did not Thor Heyerdahl and his Kontikki companions breakfast on them on a regular basis??

Yes, so they reported in the book. It is not unusual. Lots of cruising yachtsmen take a turn on deck to pick up the nights flying fish harvest. The fish do their gliding act and if they happen to knock themselves out or kill themselves colliding with the deck house, oh well, free food. More than one boat cat has enjoyed the bounty of the sea.

One guy reported being rudely awakened by having something wet flapping about on his face. Seems a flying fish came through an open port light and landed on the sleepers face. He imagined slithey tentacles preparing to drag him to a watery demise before he figured it out.

We used to see flying fish every so often off the coast of SOCAL, some pretty darned big.

I too have experienced ground effect while riding a fast bike. First I experienced dog effect followed by a brief flying experience, ending in considerable ground effect. Why would a big dog run under your front wheel?

Pat

 

[Iplayfarmer]

Ground effect DOES NOT require the aircraft to be overloaded before it happens.

I have been in and out of ground effect many many times and never had that experience. I'll accept that it is possible and that my limited experience mislead me.

Pat

Being overloaded doesn't cause ground effect, it causes crashes. Ground effect allows overloaded planes to get just high enough that when they stall is a true crash instead of just a botched take-off. You don't seem like the kind that would try to fly an overloaded plane. Therefore, it doesn't surprise me that you haven't crashed because of ground effect.

As I understand what our semi-reliable resource, Wikipedia, is saying; ground effect allows overloaded planes that otherwise would not fly to get off the ground. Once the overloaded plane attempts to climb beyond 1 or 2 wing spans off the ground, no ground effect, no lift, the plane stalls, the plane crashes on the border between US and Canada, the second definition of ground effect as described by Egon takes over, and we have a lengthy discussion of where to bury the survivors.

 

[Iplayfarmer]

Why would a big dog run under your front wheel?

Pat

I don't know, but little brothers do the same thing.

I swear it to this day, Mom! I was just riding straight down the driveway and he jumped out from behind that tree right in front of me.

 

[daTeacha]

RE flying fish, there is an asian carp that makes a habit of jumping several feet out of the water, weighs several pounds, and can cause serious bodily harm when crashing into innocent boaters. The things are among the latest exotic species found in some of the waters of Ohio. These are not the marine flying fish with the extra large pectoral fins, but large fish that jump out of the water and smack into you.

Getting back to the plane and presuming it does not get damaged by said fish, the possibility of a magic float has been overlooked. If the float has a magic belt on it which goes round and round, running backwards at the bottom of the float and forwards at the top, friction between the float and the water would be substantially reduced while producing a negative laminar flow of air over the top of the float and the bottom of the wing. This could produce negative lift, causing the plane to sink and displace more lake water.

PAGE 100!

 

[Iplayfarmer]

RE flying fish, there is an asian carp that makes a habit of jumping several feet out of the water
QUOTE]

When I first read that, I thought you had written "asian Corp." I was flat out impressed that these peons in asian corporations would be jumping out of the water. I wouldn't put it past them after some of the other stuff I've heard.

Post 992!

 

[RobS]

So, if an Asian Carp leaps out of the water into a magical airstream above the water, will it land?

 

[turnkey4099]

RE flying fish, there is an asian carp that makes a habit of jumping several feet out of the water, weighs several pounds, and can cause serious bodily harm when crashing into innocent boaters. The things are among the latest exotic species found in some of the waters of Ohio. These are not the marine flying fish with the extra large pectoral fins, but large fish that jump out of the water and smack into you.

Getting back to the plane and presuming it does not get damaged by said fish, the possibility of a magic float has been overlooked. If the float has a magic belt on it which goes round and round, running backwards at the bottom of the float and forwards at the top, friction between the float and the water would be substantially reduced while producing a negative laminar flow of air over the top of the float and the bottom of the wing. This could produce negative lift, causing the plane to sink and displace more lake
water. PAGE 100!

But if there is tank full of flying fish in the plane and it is about to run out of ground effect, can you pound on the tank, make the fish fly and thus decrease the load?

Harry K

 

[patrick_g]

But if there is tank full of flying fish in the plane and it is about to run out of ground effect, can you pound on the tank, make the fish fly and thus decrease the load?

Harry K

Harry, Ultimately any lift generated by the fish to maintain "flight" less ballistic than a near parabola is applied as a force to the containing enclosure. I fear to lighten ship, you'd have to toss them free of the plane (possibly followed by cargo in increasing order of value and decreasing order by weight till at some point you toss out passengers and then the co-pilot.) I volunteer to sit in the left seat.

Regarding ground effect causing a stall... It is a contributory factor but not a true cause. The cause of the stall is the pilot trying to "force" the plane to continue to climb after reaching the upper limit of the ground effect which had been aiding his climb and increasing the angle of attack (alpha) in a vain attempt to increase the true flight path elevation angle (beta) and get more altitude (AG) to avoid such things as tall trees, towers, buildings, cumulus granite and such.

In these instances the last thing to go through the pilot's mind as he is contemplating his failure is often the tail of the aircraft!

Pat

 

[Iplayfarmer]

Harry, Ultimately any lift generated by the fish to maintain "flight" less ballistic than a near parabola is applied as a force to the containing enclosure. I fear to lighten ship, you'd have to toss them free of the plane (possibly followed by cargo in increasing order of value and decreasing order by weight till at some point you toss out passengers and then the co-pilot.) I volunteer to sit in the left seat.

Regarding ground effect causing a stall... It is a contributory factor but not a true cause. The cause of the stall is the pilot trying to "force" the plane to continue to climb after reaching the upper limit of the ground effect which had been aiding his climb and increasing the angle of attack (alpha) in a vain attempt to increase the true flight path elevation angle (beta) and get more altitude (AG) to avoid such things as tall trees, towers, buildings, cumulus granite and such.

In these instances the last thing to go through the pilot's mind as he is contemplating his failure is often the tail of the aircraft!

Pat

Pat,

I don't think anyone is trying to say that ground effect causes a stall.

I've been trying to say what you're saying... the lack of ground effect is what facilitates the stall. I.e. "after reaching the upper limit of the ground effect which had been aiding his climb".

 

[patrick_g]

Pat,

I don't think anyone is trying to say that ground effect causes a stall.

I've been trying to say what you're saying... the lack of ground effect is what facilitates the stall. I.e. "after reaching the upper limit of the ground effect which had been aiding his climb".

Perhaps I was led astray by the following I reproduced from earlier posts, assertions that are not entirely true:

+ + + + + + + + +
"So... Ground effect will only come into play if the plane is overloaded, at which point the plane will take off due to ground effect and then stall crashing into Eddie's lake truly scaring whatever fish haven't been liquified by the magic impeller causing the backwards current.

Once the pilot climbs out of ground effect wingtip vortices will form, the wings will stall, and the aircraft will suddenly descend - usually resulting in a crash."
+ + + + + + + + + +

Many modern aircraft have special wingtips that induce a rotating component to be equal in magnitude and opposite in phase (direction) to wing tip vortices and cancel them over a relatively wide dynamic range of aerodynamic conditions, especially but not restricted to cruise configuration.

A crash is only probable if 1. the pilot does what I described earlier, try to maintain the ground effect assisted rate of climb. Pilots can get nervous when during a takeoff-climbout their VSI swings to less positive numbers or negative values. If they make the error of flying the VSI as a control instrument rather than as intended, a performance instrument, they can easily achieve a greater angle of attack than can be maintained, lose lift, and approach or enter a stall condition.

or 2. (a variant of the above) the pilot sets up an unrealistically rapid ascent after rotation and lift off (relatively easily achieved with ground effect) and gets well above the altitude where ground effect would cushion him sufficiently and after having traded off airspeed for altitude (kinetic energy for potential energy) rapidly finds himself too nose high and too low on airspeed with an ensuing stall.

With conventional (old fashioned original recipe wings) both of the above scenarios is more likely but not assured.

Note: a stall in and of itself is not dangerous to the aircraft or occupants but requires the loss of altitude for a recovery Iin "normal aircraft" and when the required loss of altitude exceeds the height above solid objects of the aircraft a lot of impromptu customizing of the airframe and the pilot's frame is likely.

Note2: If the climb after rotation is more gradual, the overweight (for available power) aircraft will gently be trapped near the top of the ground effect with no stall. It would still be a frightening thing to be flying cross country at an elevation of (say) 50-80 feet (depending on the wing loading, power available, etc.

Since the magic impeller will prevent the float plane from taking off or even moving forward, all the discussion regarding ground effect is, although of some passing interest, not applicable to the problem at hand.

Pat

 

[RobJ]

Harry, Ultimately any lift generated by the fish to maintain "flight" less ballistic than a near parabola is applied as a force to the containing enclosure. I fear to lighten ship, you'd have to toss them free of the plane (possibly followed by cargo in increasing order of value and decreasing order by weight till at some point you toss out passengers and then the co-pilot.) I volunteer to sit in the left seat.

Or just watch mythbusters once again. They did this with birds, no weight change. Of course the twist with the fish is it isn't "producing" any lift as the birds are with downward air. It's just chucking itself out of the water.

In Destin FL I saw many bass jumping out of the water in the golf course ponds.

998!!!!!

 

[patrick_g]

Or just watch mythbusters once again. They did this with birds, no weight change. Of course the twist with the fish is it isn't "producing" any lift as the birds are with downward air. It's just chucking itself out of the water.

In Destin FL I saw many bass jumping out of the water in the golf course ponds.

998!!!!!

Rob, Have you ever personally seen flying fish "jump" out of the water? How about a movie maybe?

They swim close to the surface and jump out of the water like other fish B U T once in the air they use their enlarged pectoral fins (and sometimes caudal fins depending on which kind of flying fish) to fly/glide for considerable distances. Their wings produce lift from the air flow over their fins. This is no different from a gliding or soaring bird. The transfer of momentum takes place.

Flying fish - Wikipedia, the free encyclopedia

Pat

 

[turnkey4099]

Rob, Have you ever personally seen flying fish "jump" out of the water? How about a movie maybe?

They swim close to the surface and jump out of the water like other fish B U T once in the air they use their enlarged pectoral fins (and sometimes caudal fins depending on which kind of flying fish) to fly/glide for considerable distances. Their wings produce lift from the air flow over their fins. This is no different from a gliding or soaring bird. The transfer of momentum takes place.

Flying fish - Wikipedia, the free encyclopedia

Pat

Yes, they do glide and do so for surprising distances and heights. I picked up a couple on the deck of a liberty ship...okay, a converted liberty ship but I did go overseas (1955) on the General something or other.

Harry K