mvivion
SPONSOR
Bozeman,MT
RB,
Sorry, but there's no relationship between the downwind turn discussion and the question of turning around in a small stream.
I do not disagree at all with what bearsnack says in the notion that if you misjudge the turn towards a cutbank, it ain't gonna be pretty.
And, in a straight stretch of stream, it makes no difference which way you turn, so certainly turn towards the low bank side. That is just common sense.
BUT, what I discussed was a situation where you are in a tight stretch of river, a narrow river, and trying to turn around at the upstream end of the stretch. That means there's a bend in the river at the upstream end--often a switchback so step taxiing around it is out of the question on takeoff.
Now, THINK about the water as it moves around that bend. The SPEED of the current on the outside of the bend is faster, is it not? That is precisely WHY there IS a cutbank, actually. The speed on the beach side is MUCH slower.
The floats on an average seaplane are somewhere between 16 and 20 feet long. place those things sideways in a narrow stream, and one end of those floats is GOING to be in much faster water than the other end of the floats.
If you are going upstream, and need to turn downstream for the takeoff, and you put the TOES of the floats into the slack water while trying to turn, the current will push the HEELS of your floats DOWNSTREAM, effectively defeating your attempt to turn.
So, as Bearsnack says, you beach the airplane, turn it around by hand, and start again, pointed downstream. And, in some cases that works fine. Now, consider that you're in a Cub, right side door only, and you are turning in a stream where the "beach" side is on the left and the cutbank is on the right. You try to turn toward the beach, but it doesn't work. Now, you beach, and that current starts spinning that airplane around to the right as you scramble to get out that one door and get control of the situation. By the time you get out onto the float, the plane is cartwheeling downstream in a narrow river, with cutbanks and lots of trees and brush, and no power, no steerage.
Or, you can put the TOES of those floats into the fast water, the heels into the slow water, and the plane will turn in less than HALF the distance it would take in still water. Much less. Now, this has to be done at minimum forward speed, as in dead idle, and you have to use ALL the river that is available.
Again, this is something you have to experiment with in carefully controlled circumstances FIRST--like someplace it won't hurt anything if you hit the cutbank side. They exist--look for a low cutbank, etc. Or go out in a boat and put IT sideways in a narrow fast river, and see what it does.
Again, bearsnack is absolutely correct on the hazards of mis-applying the technique that I describe. You MUST KNOW your seaplane well, and you have to have practiced this in controlled situation.
I spent many years working seaplanes every summer in different parts of Alaska, often operating in and out of small, confined streams, and generally in airplanes with only one door. That's not the best setup, but it can work.
Learn how the airplane responds to the water and current, and you can operate in some really tight spots quite safely.
But, you can't argue with physics. And, it'll amaze you how quick a seaplane will turn if you USE the current instead of fighting it.
MTV
Sorry, but there's no relationship between the downwind turn discussion and the question of turning around in a small stream.
I do not disagree at all with what bearsnack says in the notion that if you misjudge the turn towards a cutbank, it ain't gonna be pretty.
And, in a straight stretch of stream, it makes no difference which way you turn, so certainly turn towards the low bank side. That is just common sense.
BUT, what I discussed was a situation where you are in a tight stretch of river, a narrow river, and trying to turn around at the upstream end of the stretch. That means there's a bend in the river at the upstream end--often a switchback so step taxiing around it is out of the question on takeoff.
Now, THINK about the water as it moves around that bend. The SPEED of the current on the outside of the bend is faster, is it not? That is precisely WHY there IS a cutbank, actually. The speed on the beach side is MUCH slower.
The floats on an average seaplane are somewhere between 16 and 20 feet long. place those things sideways in a narrow stream, and one end of those floats is GOING to be in much faster water than the other end of the floats.
If you are going upstream, and need to turn downstream for the takeoff, and you put the TOES of the floats into the slack water while trying to turn, the current will push the HEELS of your floats DOWNSTREAM, effectively defeating your attempt to turn.
So, as Bearsnack says, you beach the airplane, turn it around by hand, and start again, pointed downstream. And, in some cases that works fine. Now, consider that you're in a Cub, right side door only, and you are turning in a stream where the "beach" side is on the left and the cutbank is on the right. You try to turn toward the beach, but it doesn't work. Now, you beach, and that current starts spinning that airplane around to the right as you scramble to get out that one door and get control of the situation. By the time you get out onto the float, the plane is cartwheeling downstream in a narrow river, with cutbanks and lots of trees and brush, and no power, no steerage.
Or, you can put the TOES of those floats into the fast water, the heels into the slow water, and the plane will turn in less than HALF the distance it would take in still water. Much less. Now, this has to be done at minimum forward speed, as in dead idle, and you have to use ALL the river that is available.
Again, this is something you have to experiment with in carefully controlled circumstances FIRST--like someplace it won't hurt anything if you hit the cutbank side. They exist--look for a low cutbank, etc. Or go out in a boat and put IT sideways in a narrow fast river, and see what it does.
Again, bearsnack is absolutely correct on the hazards of mis-applying the technique that I describe. You MUST KNOW your seaplane well, and you have to have practiced this in controlled situation.
I spent many years working seaplanes every summer in different parts of Alaska, often operating in and out of small, confined streams, and generally in airplanes with only one door. That's not the best setup, but it can work.
Learn how the airplane responds to the water and current, and you can operate in some really tight spots quite safely.
But, you can't argue with physics. And, it'll amaze you how quick a seaplane will turn if you USE the current instead of fighting it.
MTV
in a silty river, will the resistance of the silt change the turn?
