The use of ground effect.

Great video! An absolute must for low powered planes like my c140. Though I would need a pretty long field to do anything close to a zoom! Lol
 
Not going there again ,with the zoom climb???
 
Great video. I want to know what happened at 3:57 - the drone (I assume) making the video got a little close to that tree!
 
He saved the drone, very close to crash it to the trees, actually hit some branches, flying in reverse looking at my plane.
 
Zoom climb feels good!
Actually if there are tall trees around and its windy, usually gets very turbulent, I rather zoom climb than going at Vx over trees.
 
motoadve said:
I like the use ground effect quite a bit, free performance is always good to have, short field, short gravel bar, obstacles at the end, high density take offs etc.

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I liked the one where the ground fell out of ground effect instead of you climbing out of it
 
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
 
Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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Ground effect is very real. It greatly improves lift/drag ratios and efficiency. One example that comes to mind is Wing In Ground Effect aircraft (?) which do very well skimming over water at a few feet high, but generally lack the power to fly more than a wingspan or so above the surface. Without ground effect they wouldn't fly. Other examples are/were Paul Maccready's Gossamer Albatross and Gossamer Condor man powered aircraft, neither of which could climb out of ground effect for very long given the limited power available, but which could fly for hours (in the case of the Albatross) in ground effect.
 
Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything.
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I have. Very practical things. It allows leaving the ground early and accelerating to climb speed in soft field and very high density altitude takeoffs. On landing, I've seen pilots transitioning from high drag Cessnas and Pipers to low-drag, more efficient winged Mooneys and Diamonds have trouble with the need for a much slower pullback in the flare because the airplane continues to fly much longer.
 
Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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And, there are some pretty good studies looking at the PC6 wrist acupuncture point stimulation for control of Post Op Nausea and Vomiting with pretty good efficacy.


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Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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It can help a heavy plane on a hot day make it to the accident scene!
 
Juliet Hotel said:
[...] People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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Not sure how you came up with that, but there is tons of research proofing otherwise. Just google "ground effect aerodynamics research". I guess every pilot also experienced how particularly low wing aircraft tend to float once they get close to the ground.

Some birds, like pelicans, also use this ground effect to fly more efficiently.
Check out this video and note how little they have to flap their wings to keep going:
Pelicans, pushing forward against a pretty stiff wind:
Engineers also work(ed) on ground effect vehicles: http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml

Also, when taking off from a rough / short airstrip (like a sandbar) it is desirable to get the plane in the air as soon as possible and to accelerate in ground effect until it is ready to fly, what means at least Vx, better Vy. I think we have all seen videos in which the pilot gets the plane off the ground in a high DA situation, but tries to climb immediately instead of first accelerating in ground effect, only to mush into something at the end of the runway.

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Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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When loaded on a hot day with an ag plane on a short runway it can be the difference in you getting over the fence on the end or not.
 
Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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I have used ground effect even in the Piper Chieftains. In Alaska during spring breakup and the runways are just nasty sloppy muddy, real soft field operations instead of hard pavement pretend soft field. Getting the Chieftain off the ground and into ground effect means the plane is in the air before VySe but staying in ground effect until past the blue line then climb. On the tundra this can sometimes mean passing the end of the runway before I start to climb.

But I never tried acupuncture, that scares the heck outta me....:lol::lol:
 
Watch the STOL contest at Valdez next week. You’ll see a demonstration of the use of ground effect and how ground effect stall speed is slower than stall speed at altitude. In cool temps at sea level? Better yet.

Acupuncture is awesome, by the way. Not for everything but it sure helps for some things. I fall asleep every time. No stress.
 
kyleb said:
Ground effect is very real.
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I'm not saying its not real, I'm saying its like acupuncture. Which is to say that it exists and you can do it, but it doesn't really do very much.
midlifeflyer said:
On landing, I've seen pilots transitioning from high drag Cessnas and Pipers to low-drag, more efficient winged Mooneys and Diamonds have trouble with the need for a much slower pullback in the flare because the airplane continues to fly much longer.
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See this right here is exactly what I'm talking about. I learned to fly in a C150 and then went on to flying 172s and 182s. And then I went on to do a ton of time in a Mooney. Then I went pro and did a ton of time in supercubs and a much smaller amount of time in a pawnee. All out of a short tight grass field with trees on three sides. So I did a lot of high wing stuff interspersed with time in low wing stuff. And I never once had to think about 'oh wait this is low wing, better allow for ground effect and all that..' Near as I could tell, once you really knew how to land, you knew how to land and it didn't matter what you flew, they all landed about the same. Even the Mooney and they're notorious for floating forever. I would think about the weight and conditions and adjust my speed accordingly, but I never once gave an ounce of thought to wing position or ground effect and I always got down and stopped in book numbers or close to it.
Stewartb said:
Acupuncture is awesome, by the way. Not for everything but it sure helps for some things. I fall asleep every time. No stress.
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Studies have shown placing needles in very specific areas of the body does have a real and measurable effect. Those studies have also shown that placing needles in completely random areas also has the same effect. They also show that leading the patient to believe needles have been placed when in fact no needles have been applied also has the same effect. Placebo is a powerful drug. Ask for it by name.
 
Ground effect is almost undetectable when the wing is more than a half-wingspan above the surface. The pilot of a high-wing Cessna with its mains four feet off the ground is mostly wasting his time. A sailplane with its 45-foot wing and very small ground clearance has to deal with it big time.

And zoom climbs. They have killed a lot of people who didn't understand accelerated stalls. An airplane that stalls at 50 knots, zooming along at 80, and then pulling 2G in the transition to the climb, has increased the stall speed by the square root of that 2, which is 1.41 times 50, or 71 kt, only 9 kt under the stall. Throw a bank into it as you pull and that margin decreases even more. Pull just a little harder in a straight-ahead zoom, say 2.6G, and it's all over. It's what kills so many trying to impress the friends on the ground.
 
Juliet Hotel said:
I
See this right here is exactly what I'm talking about. I learned to fly in a C150 and then went on to flying 172s and 182s. And then I went on to do a ton of time in a Mooney. Then I went pro and did a ton of time in supercubs and a much smaller amount of time in a pawnee. All out of a short tight grass field with trees on three sides. So I did a lot of high wing stuff interspersed with time in low wing stuff. And I never once had to think about 'oh wait this is low wing, better allow for ground effect and all that..' Near as I could tell, once you really knew how to land, you knew how to land and it didn't matter what you flew, they all landed about the same. Even the Mooney and they're notorious for floating forever. I would think about the weight and conditions and adjust my speed accordingly, but I never once gave an ounce of thought to wing position or ground effect and I always got down and stopped in book numbers or close to it.
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Well yes, of course, but that's all based on your subjective experience, not objective science. I definitely don't have your level of experience but having flown over 30 types of singles, the reality for me is mostly the same. With some exceptions, after my third, transitions started getting easier and easier. When I am landing, I don't think about the wing and the science either. When I am teaching, however, I never found, "they are all the same; just land it" to be particularly helpful to someone who is having a landing issue when transitioning to something new.

You are without a doubt dealing with differences in aircraft performance in ground effect when you are landing. You just don't have do it consciously. You don't think about wing position and landing ground effect any more than you think about the width of your car when you drive into a garage.
 
Stewartb said:
2 billion Chinese and 3000 years of history are a pretty good study.
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Actually not 3000 years worth of history. It was indeed used about 3000 years ago but had pretty much been written off as nothing more than superstition and all but died off about 2500 years ago. And it pretty much stayed that way until the 1950's when Chinese Communist party leader Mao Zedong revived it part of an initiative to reassure the Chinese people that their Government had a plan to keep them healthy even though the country could not afford to supply most of the Western based medical practices in use at the time. Then the Americans with their pesky free enterprise system got hold of it and the rest as they say is history.

Believe me I do not disregard that people use it and are helped by it. But I also do not disregard that there are lots of studies that show placebo effect to be very powerful and also lots of studies that show acupuncture to be no more effective than placepbo.
 
Juliet Hotel said:
Studies have shown placing needles in very specific areas of the body does have a real and measurable effect. Those studies have also shown that placing needles in completely random areas also has the same effect. They also show that leading the patient to believe needles have been placed when in fact no needles have been applied also has the same effect. Placebo is a powerful drug. Ask for it by name.
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I am a supplier for the wonder drug Placebex. It is 98% as effective as every other drug on the market, has 98% of the same side effects as all other drugs, yet only costs as much as sugar compressed into pill form. Although we have to add some nasty tasting stuff so you think it is the same as all those other drugs.
 
midlifeflyer said:
Well yes, of course, but that's all based on your subjective experience, not objective science.
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You are very correct, completely subjective. I'm married to a scientist who does studies for a living, but I'm not one myself so subjective all I have to go on.
You are without a doubt dealing with differences in aircraft performance in ground effect when you are landing. You just don't have do it consciously.
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And this is the very point I was making. I'm not saying that ground effect is something that does not exist or can't be measured. If you put your mind to it, you can identify it and measure it for sure. What I'm saying is I don't buy that it ever makes a hill of beans worth of difference.

If you get the plane off the ground and push the nose over so it stops climbing while leaving the throttle at the firewall, the plane will build speed. And a plane with an abundance of speed will climb like the Dickens for a few seconds when you haul back on the elevator. No one disputes that.

But it will do that whether the wheels are 2' off the ground or 20' off the ground or 200' off the ground. If you go the firewall with the throttle and push the nose over so it doesn't climb and hold it there for 8 seconds, it will pop up like its shot out of canon when you haul back on the elevator at pretty much any altitude that is a couple thousand feet below the service ceiling. So is it really ground effect at that point or is it just you've got a boatload more speed than you need for straight and level?

I know the big tire crowd will swear otherwise but I'm in the camp that says it has way more do to with excess speed than anything to do with ground effect. I would love to believe otherwise but I'd need to see data to support it and so far I've not seen where any of the big tire crowd could produce it.
 
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Matthew Rogers said:
I am a supplier for the wonder drug Placebex. It is 98% as effective as every other drug on the market, has 98% of the same side effects as all other drugs, yet only costs as much as sugar compressed into pill form. Although we have to add some nasty tasting stuff so you think it is the same as all those other drugs.
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I wish you could produce such a drug. If for no other reason than it would enable you to afford to own and pilot any plane you wanted up to and including a 747. ;)
 
Juliet Hotel said:
You are very correct, completely subjective. I'm married to a scientist who does studies for a living, but I'm not one myself so subjective all I have to go on.
And this is the very point I was making. I'm not saying that ground effect is something that does not exist or can't be measured. If you put your mind to it, you can identify it and measure it for sure. What I'm saying is I don't buy that it ever makes a hill of beans worth of difference.
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It does make a difference in soft-field takeoffs. The airplane, if the nose is held high, will lift off at a little below stall speed due to the ground effect, but the pilot must modulate the attitude to keep those wheels just above the surface while the speed builds to climb speed. If one just keeps the nose up after liftoff, the airplane will rise as far as the ground effect will let it, then it mushes along until it hits something.

In hot and high situations, it's well known to result in crashes. Again, it gets off but can't climb out of ground effect.

My Jodel, a low-wing airplane with the trailing edge only about 15" off the ground, stalls at 40 but will lift off at 30 or so if I keep the tail on the ground. Very noticeable ground effect.
 
Dan Thomas said:
It does make a difference in soft-field takeoffs. The airplane, if the nose is held high, will lift off at a little below stall speed due to the ground effect, but the pilot must modulate the attitude to keep those wheels just above the surface while the speed builds to climb speed. If one just keeps the nose up after liftoff, the airplane will rise as far as the ground effect will let it, then it mushes along until it hits something.

In hot and high situations, it's well known to result in crashes. Again, it gets off but can't climb out of ground effect.
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I've seen the videos of planes that managed to get off the ground but not climb. No dispute there. What I haven't seen nor experienced is a situation where the plane got off the ground but would not climb unless kept in ground effect and allowed to accelerate in ground effect. If you've experienced that then I bow to your prowess but I've never been in a situation where that was the case. In my experience you can force it airborne before you have enough speed for it to really fly. But as soon as you get the wheels off the grass, airspeed goes up which gets you immediately to the point where its going to fly no matter what. So net effect is she gets in the air and starts climbing and keeps climbing.

So I've seen the youtube clips where it got in the air but wouldn't climb no matter what and I've seen where it gets in the air starts climbing no matter what you do. I guess in theory its possible you could find that one specific weight and altitude where it'll get off the ground but not climb untll you push it over and let it accelerate. Seems very reasonable actually. But if you're not at the critical weight and altitude, then how much of the performance you're getting from getting airborne and pushing the nose over is due to ground effect and how much is due to just the fact that throttle to the firewall plus hold the nose down equals speed and speed equals climb?

My answer is not much. I would love to be proved wrong. But until I'm proved wrong, I'm going to stick with not much.
 
Juliet Hotel said:
I've seen the videos of planes that managed to get off the ground but not climb. No dispute there. What I haven't seen nor experienced is a situation where the plane got off the ground but would not climb unless kept in ground effect and allowed to accelerate in ground effect. If you've experienced that then I bow to your prowess but I've never been in a situation where that was the case. In my experience you can force it airborne before you have enough speed for it to really fly. But as soon as you get the wheels off the grass, airspeed goes up which gets you immediately to the point where its going to fly no matter what. So net effect is she gets in the air and starts climbing and keeps climbing.

So I've seen the youtube clips where it got in the air but wouldn't climb no matter what and I've seen where it gets in the air starts climbing no matter what you do. I guess in theory its possible you could find that one specific weight and altitude where it'll get off the ground but not climb untll you push it over and let it accelerate. Seems very reasonable actually. But if you're not at the critical weight and altitude, then how much of the performance you're getting from getting airborne and pushing the nose over is due to ground effect and how much is due to just the fact that throttle to the firewall plus hold the nose down equals speed and speed equals climb?

My answer is not much. I would love to be proved wrong. But until I'm proved wrong, I'm going to stick with not much.
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When the field is soft, as in long, wet grass or mud, you'll never reach takeoff speed without the soft-field technique. There's just too much friction, and it gets worse as you accelerate, so in such cases getting the thing airborne as soon as it possible can gets rid of that friction and it will accelerate to climb speed. I've experienced it numerous times, and taught it.

You wouldn't believe how much wheat stubble will stop your acceleration once you get rolling at 20 or 30 MPH. Some pilots will use full flap to get off, then they're busy with pitch and flaps to maintain minimal altitude while accelerating.
 
Juliet Hotel said:
I've seen the videos of planes that managed to get off the ground but not climb. No dispute there. What I haven't seen nor experienced is a situation where the plane got off the ground but would not climb unless kept in ground effect and allowed to accelerate in ground effect. If you've experienced that then I bow to your prowess but I've never been in a situation where that was the case. In my experience you can force it airborne before you have enough speed for it to really fly. But as soon as you get the wheels off the grass, airspeed goes up which gets you immediately to the point where its going to fly no matter what. So net effect is she gets in the air and starts climbing and keeps climbing.

So I've seen the youtube clips where it got in the air but wouldn't climb no matter what and I've seen where it gets in the air starts climbing no matter what you do. I guess in theory its possible you could find that one specific weight and altitude where it'll get off the ground but not climb untll you push it over and let it accelerate. Seems very reasonable actually. But if you're not at the critical weight and altitude, then how much of the performance you're getting from getting airborne and pushing the nose over is due to ground effect and how much is due to just the fact that throttle to the firewall plus hold the nose down equals speed and speed equals climb?

My answer is not much. I would love to be proved wrong. But until I'm proved wrong, I'm going to stick with not much.
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It got this thing to fly. Proof enough it’s effective for me.

Beriev_VVA-14_in_2010.jpg
 
Juliet Hotel said:
Warning: This post may contain blasphemy.

I always thought of ground effect sort of the same way I think about acupuncture. People use it and swear by it, but I've never personally seen it do anything and as far as I know, science is unable to prove that its use has any measurable effectiveness.
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You may 'think' it does nothing, but when you start flying on the edge of the flight envelope, particularly in high/hot environments, or short strips, you will become a believer. The problem is, to prove it does, or does not exist, can become very expensive, not to mention painful or even deadly.

Or, you could just learn to fly helicopter and then you really begin to learn about ground effect. The performance charts even have 'OGE' and IGE' (Out of Ground Effect and In Ground Effect) hover performance, and you better pay attention to it.

PJ
 
Juliet Hotel said:
I'm not saying its not real, I'm saying its like acupuncture. Which is to say that it exists and you can do it, but it doesn't really do very much.
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Well, I'd say the difference between being able to hold a hover IGE and not being able to hold a hover OGE is a pretty big deal. It's helpful, useful and continues to bring the fat checks in. It's not just important for the hover, but your entire approach and take off procedure.

PJ
 
This guy has to be a troll. How can you be a pilot and not have experienced ground effect? Or see the benefits or pitfalls?


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There’s more than couple NTSB accident reports, with fatalities, where ground effect was a killer. Usually a hot day and/or high altitude airports. Plane takes off, gets airborne, but can’t climb out of ground effect. It can stay in the air with the ground effect but can’t get any higher. Then rock and tree effect enters the picture
 
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