What is the offset in a seaplane's hull?
$begingroup$
I noticed there is a little offset in a seaplane's hull (highlighted in the following picture). I suppose this is useful as it exists in all the seaplanes I know. It seems it does not help hydrodynamics neither aerodynamics. I could not find any clue by myself as I don't know this feature's name.
My question, what is its name and purpose?
(wikimedia.org)
aircraft-design feature-identification fuselage seaplane
edited 16 hours ago
ymb1
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
$endgroup$
add a comment |
$begingroup$
I noticed there is a little offset in a seaplane's hull (highlighted in the following picture). I suppose this is useful as it exists in all the seaplanes I know. It seems it does not help hydrodynamics neither aerodynamics. I could not find any clue by myself as I don't know this feature's name.
My question, what is its name and purpose?
(wikimedia.org)
aircraft-design feature-identification fuselage seaplane
edited 16 hours ago
ymb1
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
$endgroup$
add a comment |
$begingroup$
I noticed there is a little offset in a seaplane's hull (highlighted in the following picture). I suppose this is useful as it exists in all the seaplanes I know. It seems it does not help hydrodynamics neither aerodynamics. I could not find any clue by myself as I don't know this feature's name.
My question, what is its name and purpose?
(wikimedia.org)
aircraft-design feature-identification fuselage seaplane
edited 16 hours ago
ymb1
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
$endgroup$
I noticed there is a little offset in a seaplane's hull (highlighted in the following picture). I suppose this is useful as it exists in all the seaplanes I know. It seems it does not help hydrodynamics neither aerodynamics. I could not find any clue by myself as I don't know this feature's name.
My question, what is its name and purpose?
(wikimedia.org)
aircraft-design feature-identification fuselage seaplane
aircraft-design feature-identification fuselage seaplane
edited 16 hours ago
ymb1
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
edited 16 hours ago
ymb1
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
edited 16 hours ago
ymb1
69.8k7222371
edited 16 hours ago
ymb1
69.8k7222371
edited 16 hours ago
ymb1
69.8k7222371
69.8k7222371
asked 16 hours ago
Manu HManu H
5,5701058137
asked 16 hours ago
Manu HManu H
5,5701058137
asked 16 hours ago
Manu HManu H
5,5701058137
5,5701058137
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
That's called the step. Without it, you'd have to fight against the buoyancy of the rear end of the hull when you rotate for takeoff.
However, a seaplane float or hull must be designed to permit the seaplane to be rotated or pitched up to increase the wing's angle of attack and gain the most lift for takeoffs and landings. Thus, the underside of the float or hull has a sudden break in its longitudinal lines at the approximate point around which the seaplane rotates into the lift off attitude. This break, called a "step," also provides a means of interrupting the capillary or adhesive properties of the water.
The water can then flow freely behind the step, resulting in minimum surface friction so the seaplane can lift out of the water. The steps are located slightly behind the airplane's centre of gravity, approximately at the point where the main wheels of a landplane are located. If the steps were located to far aft or forward of this point, it would be difficult, if not impossible, to rotate the airplane into a pitch-up attitude prior to planing (rising partly out of the water while moving at high speed) or lift off. Although steps are necessary, the sharp break along the float's or hull's underside causes structural stress concentration, and in flight produces considerable drag because of the eddying turbulence it creates in the airflow.
answered 16 hours ago
HobbesHobbes
4,0421017
$endgroup$
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
add a comment |
$begingroup$
It's called a hull step. Below is with and without:
It reduces water drag. As the plane gains speed and the aft body is lifted, only the forward hull will be in contact with the water.
Source: Laté 631 Replica - Chapter 3 - Hydrodynamics
answered 16 hours ago
ymb1ymb1
69.8k7222371
$endgroup$
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
That's called the step. Without it, you'd have to fight against the buoyancy of the rear end of the hull when you rotate for takeoff.
However, a seaplane float or hull must be designed to permit the seaplane to be rotated or pitched up to increase the wing's angle of attack and gain the most lift for takeoffs and landings. Thus, the underside of the float or hull has a sudden break in its longitudinal lines at the approximate point around which the seaplane rotates into the lift off attitude. This break, called a "step," also provides a means of interrupting the capillary or adhesive properties of the water.
The water can then flow freely behind the step, resulting in minimum surface friction so the seaplane can lift out of the water. The steps are located slightly behind the airplane's centre of gravity, approximately at the point where the main wheels of a landplane are located. If the steps were located to far aft or forward of this point, it would be difficult, if not impossible, to rotate the airplane into a pitch-up attitude prior to planing (rising partly out of the water while moving at high speed) or lift off. Although steps are necessary, the sharp break along the float's or hull's underside causes structural stress concentration, and in flight produces considerable drag because of the eddying turbulence it creates in the airflow.
answered 16 hours ago
HobbesHobbes
4,0421017
$endgroup$
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
add a comment |
$begingroup$
That's called the step. Without it, you'd have to fight against the buoyancy of the rear end of the hull when you rotate for takeoff.
However, a seaplane float or hull must be designed to permit the seaplane to be rotated or pitched up to increase the wing's angle of attack and gain the most lift for takeoffs and landings. Thus, the underside of the float or hull has a sudden break in its longitudinal lines at the approximate point around which the seaplane rotates into the lift off attitude. This break, called a "step," also provides a means of interrupting the capillary or adhesive properties of the water.
The water can then flow freely behind the step, resulting in minimum surface friction so the seaplane can lift out of the water. The steps are located slightly behind the airplane's centre of gravity, approximately at the point where the main wheels of a landplane are located. If the steps were located to far aft or forward of this point, it would be difficult, if not impossible, to rotate the airplane into a pitch-up attitude prior to planing (rising partly out of the water while moving at high speed) or lift off. Although steps are necessary, the sharp break along the float's or hull's underside causes structural stress concentration, and in flight produces considerable drag because of the eddying turbulence it creates in the airflow.
answered 16 hours ago
HobbesHobbes
4,0421017
$endgroup$
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
add a comment |
$begingroup$
That's called the step. Without it, you'd have to fight against the buoyancy of the rear end of the hull when you rotate for takeoff.
However, a seaplane float or hull must be designed to permit the seaplane to be rotated or pitched up to increase the wing's angle of attack and gain the most lift for takeoffs and landings. Thus, the underside of the float or hull has a sudden break in its longitudinal lines at the approximate point around which the seaplane rotates into the lift off attitude. This break, called a "step," also provides a means of interrupting the capillary or adhesive properties of the water.
The water can then flow freely behind the step, resulting in minimum surface friction so the seaplane can lift out of the water. The steps are located slightly behind the airplane's centre of gravity, approximately at the point where the main wheels of a landplane are located. If the steps were located to far aft or forward of this point, it would be difficult, if not impossible, to rotate the airplane into a pitch-up attitude prior to planing (rising partly out of the water while moving at high speed) or lift off. Although steps are necessary, the sharp break along the float's or hull's underside causes structural stress concentration, and in flight produces considerable drag because of the eddying turbulence it creates in the airflow.
answered 16 hours ago
HobbesHobbes
4,0421017
$endgroup$
That's called the step. Without it, you'd have to fight against the buoyancy of the rear end of the hull when you rotate for takeoff.
However, a seaplane float or hull must be designed to permit the seaplane to be rotated or pitched up to increase the wing's angle of attack and gain the most lift for takeoffs and landings. Thus, the underside of the float or hull has a sudden break in its longitudinal lines at the approximate point around which the seaplane rotates into the lift off attitude. This break, called a "step," also provides a means of interrupting the capillary or adhesive properties of the water.
The water can then flow freely behind the step, resulting in minimum surface friction so the seaplane can lift out of the water. The steps are located slightly behind the airplane's centre of gravity, approximately at the point where the main wheels of a landplane are located. If the steps were located to far aft or forward of this point, it would be difficult, if not impossible, to rotate the airplane into a pitch-up attitude prior to planing (rising partly out of the water while moving at high speed) or lift off. Although steps are necessary, the sharp break along the float's or hull's underside causes structural stress concentration, and in flight produces considerable drag because of the eddying turbulence it creates in the airflow.
answered 16 hours ago
HobbesHobbes
4,0421017
answered 16 hours ago
HobbesHobbes
4,0421017
answered 16 hours ago
HobbesHobbes
4,0421017
answered 16 hours ago
HobbesHobbes
4,0421017
4,0421017
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
add a comment |
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
3
3
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
$begingroup$
Re the drag in flight, an obvious question would be whether anyone had a retractable fairing behind the step to solve that problem? I hit Google and found a few places speculating about that (including US patent US6042052A in 1998), but no evidence of designers actually using one.
$endgroup$
– Graham
5 hours ago
add a comment |
$begingroup$
It's called a hull step. Below is with and without:
It reduces water drag. As the plane gains speed and the aft body is lifted, only the forward hull will be in contact with the water.
Source: Laté 631 Replica - Chapter 3 - Hydrodynamics
answered 16 hours ago
ymb1ymb1
69.8k7222371
$endgroup$
add a comment |
$begingroup$
It's called a hull step. Below is with and without:
It reduces water drag. As the plane gains speed and the aft body is lifted, only the forward hull will be in contact with the water.
Source: Laté 631 Replica - Chapter 3 - Hydrodynamics
answered 16 hours ago
ymb1ymb1
69.8k7222371
$endgroup$
add a comment |
$begingroup$
It's called a hull step. Below is with and without:
It reduces water drag. As the plane gains speed and the aft body is lifted, only the forward hull will be in contact with the water.
Source: Laté 631 Replica - Chapter 3 - Hydrodynamics
answered 16 hours ago
ymb1ymb1
69.8k7222371
$endgroup$
It's called a hull step. Below is with and without:
It reduces water drag. As the plane gains speed and the aft body is lifted, only the forward hull will be in contact with the water.
Source: Laté 631 Replica - Chapter 3 - Hydrodynamics
answered 16 hours ago
ymb1ymb1
69.8k7222371
answered 16 hours ago
ymb1ymb1
69.8k7222371
answered 16 hours ago
ymb1ymb1
69.8k7222371
answered 16 hours ago
ymb1ymb1
69.8k7222371
69.8k7222371
add a comment |
add a comment |
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