Just curious: Water landing question

What kind of space does it take to land/takeoff in a plane with
floats? I realize there are all sorts of rules about where one can do
this but I have a relative with a ranch that has a fairly decent sized
body of water on it. This is Texas, so its pretty flat with neglible
trees and I wondered if a plane could be put down there. I tried
looking around a little online but couldn't find anything that spelled
it out.

On Jan 28, 2:35*pm, es330td wrote:
What kind of space does it take to land/takeoff in a plane with
floats? *I realize there are all sorts of rules about where one can do
this but I have a relative with a ranch that has a fairly decent sized
body of water on it. *This is Texas, so its pretty flat with neglible
trees and I wondered if a plane could be put down there. *I tried
looking around a little online but couldn't find anything that spelled
it out.

It depends on the plane but it doesn't take much. If the water is not
glassy the landing can be very short. Both takeoffs and landings can
require more space if the water is glassy but you could always choose
to not fly at those times or just ensure you have enough space. Is
this body of water somewhat clear or do you have a lot of things
floating in it (logs, etc)?

-Robert, CFII (land and sea)

It depends on the plane but it doesn't take much. If the water is not
glassy the landing can be very short. Both takeoffs and landings can
require more space if the water is glassy but you could always choose
to not fly at those times or just ensure you have enough space. Is
this body of water somewhat clear or do you have a lot of things
floating in it (logs, etc)?

-Robert, CFII (land and sea)


Robert,

Out of my pure ignorance, what does glassy water have to do with
TO/Landing distance? I have been searching on the internet trying to
find something educational, but not having much luck.

I would think the Landing would be longer because the lack of ripples
would result in less resistance in the water, but I would think the TO
would be shorter for the same reason. What am I missing?

Mike

On Jan 29, 12:04*pm, Mike Flying 8 wrote:

Out of my pure ignorance, what does glassy water have to do with
TO/Landing distance? *I have been searching on the internet trying to
find something educational, but not having much luck. *

I would think the Landing would be longer because the lack of *ripples
would result in less resistance in the water, but I would think the TO
would be shorter for the same reason. *What am I missing?

I'm just a pilot and not a hyrodynamic engineer so I'll try my best.
The reason landing is longer is because you have no idea how high
above the water you are. So you try to cross over the shore around
5-10 feet and then just set up a slow decent until you feel the slash.
That tends to take up more space since you're waitng for the water.

The take off is longer because the floats stick to the water. I'm not
sure how to better explain it but you can certainly feel it. When the
water is choppy the floats come right off the water but when its
smooth you can actually feel the water pulling on the floats as they
try to pull away. Once the floats break free of the smooth water its
feels like you just got released and you feel a noticable speed
increase in ground affect.

-robert

On Jan 29, 5:27*pm, "Robert M. Gary" wrote:
On Jan 29, 12:04*pm, Mike Flying 8 wrote:

Out of my pure ignorance, what does glassy water have to do with
TO/Landing distance? *I have been searching on the internet trying to
find something educational, but not having much luck. *

I would think the Landing would be longer because the lack of *ripples
would result in less resistance in the water, but I would think the TO
would be shorter for the same reason. *What am I missing?

I'm just a pilot and not a hyrodynamic engineer so I'll try my best.
The reason landing is longer is because you have no idea how high
above the water you are. So you try to cross over the shore around
5-10 feet and then just set up a slow decent until you feel the slash.
That tends to take up more space since you're waitng for the water.

The take off is longer because the floats stick to the water. I'm not
sure how to better explain it but you can certainly feel it. When the
water is choppy the floats come right off the water but when its
smooth you can actually feel the water pulling on the floats as they
try to pull away. Once the floats break free of the smooth water its
feels like you just got released and you feel a noticable speed
increase in ground affect.

-robert

Is this what they mean by "getting on the steps"?

Wil

William Hung wrote in

:

Is this what they mean by "getting on the steps"?

Getting on the step is getting up and planing on the water during
takeoff.

--

On Jan 29, 3:34*pm, William Hung wrote:
On Jan 29, 5:27*pm, "Robert M. Gary" wrote:





On Jan 29, 12:04*pm, Mike Flying 8 wrote:

Out of my pure ignorance, what does glassy water have to do with
TO/Landing distance? *I have been searching on the internet trying to
find something educational, but not having much luck. *

I would think the Landing would be longer because the lack of *ripples
would result in less resistance in the water, but I would think the TO
would be shorter for the same reason. *What am I missing?

I'm just a pilot and not a hyrodynamic engineer so I'll try my best.
The reason landing is longer is because you have no idea how high
above the water you are. So you try to cross over the shore around
5-10 feet and then just set up a slow decent until you feel the slash.
That tends to take up more space since you're waitng for the water.

The take off is longer because the floats stick to the water. I'm not
sure how to better explain it but you can certainly feel it. When the
water is choppy the floats come right off the water but when its
smooth you can actually feel the water pulling on the floats as they
try to pull away. Once the floats break free of the smooth water its
feels like you just got released and you feel a noticable speed
increase in ground affect.

-robert

Is this what they mean by "getting on the steps"?

No. Getting on the step means the floats are not so deep in the water.
They are riding higher in the water so there is less drag. I believe
the extra take off distance required of a glassy water take off might
be because of surface tension. You don't have that in waves. In any
case, I just fly them, I can't claim a detailed knowledge of why the
water reacts that way.

-robert

I'm just a pilot and not a hyrodynamic engineer so I'll try my best.
The reason landing is longer is because you have no idea how high
above the water you are. So you try to cross over the shore around
5-10 feet and then just set up a slow decent until you feel the slash.
That tends to take up more space since you're waitng for the water.

The take off is longer because the floats stick to the water. I'm not
sure how to better explain it but you can certainly feel it. When the
water is choppy the floats come right off the water but when its
smooth you can actually feel the water pulling on the floats as they
try to pull away. Once the floats break free of the smooth water its
feels like you just got released and you feel a noticable speed
increase in ground affect.

-robert

Very interesting. Thanks for taking the time to explain it to me.

Now I just wonder why the floats would stick?!?! I am going to have
to find something that I can read about this.

Man would I love to try that sometime... That has got to be one of the
coolest things ever!

On Jan 29, 5:35 pm, Mike Flying 8 wrote:

Now I just wonder why the floats would stick?!?! I am going to have
to find something that I can read about this.

Something to do with the lowered pressure caused by the water's
velocity, just like Bernoulli says. Once you break free of the water,
the airplane accelerates quickly. Sort of like leaving a bunch of
draggy weight behind.
Molt Taylor, in his amphibious Coot, had air inlets just ahead
of the sterp, and air was ducted through tubes to vents in the
backside of the step itself to aerate the water a little. It got on
the step faster. If the water is a little choppy, getting off is
faster because of the same sort of thing: a bit of turbulence against
the hull reduces the water's hold on the airplane.

Dan

"Mike Flying 8" wrote

Now I just wonder why the floats would stick?!?! I am going to have
to find something that I can read about this.

If you are able to get half of the water to actually be air, be it waves or
bubbles, that would mean you reduced the wetted surface contact by half, and
the drag by half. As much drag as water has, that would make a tremendous
difference.

Getting on the step, well, the step is the part of the float or hull where
the float takes about a 8" jump, upwards, so the back part of the float is
not as tall. (assume the top of the float is flat)

The step, (because it looks like an upside-down step) is usually slightly
behind the CG. When you get going fast enough, you are on the step when the
whole back (all aft of the step) is out of the water. You now are about half
out of the water, and have a lot less drag, so you quickly accelerate to
flying speed.

When you are going fast enough, you put a small amount of back pressure on
the stick, and get some more positive attack, and you pivot about the step
and the wing lifts you up and out of the water.

At that point, you can make a leisurely climb out, or if you have trees or
something to clear, you ease off and let the plane accelerate in ground
effect, the zoom up and over the trees on the bank.

So, getting on the step is the key to getting the plane quickly hauling ass!
--
Jim in NC