Why would a propellor have blades of different lengths?Are there design differences between propellers powered by air (wind-power) and propellers for aviation?Why don't helicopter blades look like other propellers?Why don't aeroplanes use propellers with more blades like the intake on a fanjet?How do the propeller blades accelerate air resulting in thrust to push an aircraft forward?Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?Why are there different number of propeller blades on the inboard and outboard engines?In what way are the airfoils used for a propeller different from the ones used in turbofan engine?Why divide the blades of a 9 blade propeller into 3 groups?Propeller Characteristics at Different AltitudesWould a ringed propeller have any advantage over a standard propeller?
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Why would a propellor have blades of different lengths?
Are there design differences between propellers powered by air (wind-power) and propellers for aviation?Why don't helicopter blades look like other propellers?Why don't aeroplanes use propellers with more blades like the intake on a fanjet?How do the propeller blades accelerate air resulting in thrust to push an aircraft forward?Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?Why are there different number of propeller blades on the inboard and outboard engines?In what way are the airfoils used for a propeller different from the ones used in turbofan engine?Why divide the blades of a 9 blade propeller into 3 groups?Propeller Characteristics at Different AltitudesWould a ringed propeller have any advantage over a standard propeller?
$begingroup$
The Schempp-Hirth Duo Discus T powered glider has a five-bladed propeller, with blades of different lengths.
What is the purpose of such an arrangement?
propeller
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
$endgroup$
add a comment |
$begingroup$
The Schempp-Hirth Duo Discus T powered glider has a five-bladed propeller, with blades of different lengths.
What is the purpose of such an arrangement?
propeller
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
$endgroup$
$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago
add a comment |
$begingroup$
The Schempp-Hirth Duo Discus T powered glider has a five-bladed propeller, with blades of different lengths.
What is the purpose of such an arrangement?
propeller
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
$endgroup$
The Schempp-Hirth Duo Discus T powered glider has a five-bladed propeller, with blades of different lengths.
What is the purpose of such an arrangement?
propeller
propeller
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
asked 8 hours ago
Daniele ProcidaDaniele Procida
8,2611 gold badge38 silver badges73 bronze badges
8,2611 gold badge38 silver badges73 bronze badges
$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago
add a comment |
$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago
$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
You are right. They are unequal length blades. Schempp refers to the propeller as being "noise optimized" and you can see that the blades are free to flap (forward) like helicopter blades (which flap up) so that the asymmetric thrust axis from having the propeller disc offset from the rotational axis doesn't place bending loads on the hub. And obviously, the blades will be mass balanced to place the center of gravity at the hub axis.
I'll go out on a limb here and say that some genius figured out a way to reduce the horrific noise level caused by such a small propeller by having the blade tips each run in a slightly different path of rotation. Brilliant.
And here it is in action where the eccentric blade disc can be clearly seen.
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
$endgroup$
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
add a comment |
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1 Answer
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1 Answer
1
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$begingroup$
You are right. They are unequal length blades. Schempp refers to the propeller as being "noise optimized" and you can see that the blades are free to flap (forward) like helicopter blades (which flap up) so that the asymmetric thrust axis from having the propeller disc offset from the rotational axis doesn't place bending loads on the hub. And obviously, the blades will be mass balanced to place the center of gravity at the hub axis.
I'll go out on a limb here and say that some genius figured out a way to reduce the horrific noise level caused by such a small propeller by having the blade tips each run in a slightly different path of rotation. Brilliant.
And here it is in action where the eccentric blade disc can be clearly seen.
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
$endgroup$
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
add a comment |
$begingroup$
You are right. They are unequal length blades. Schempp refers to the propeller as being "noise optimized" and you can see that the blades are free to flap (forward) like helicopter blades (which flap up) so that the asymmetric thrust axis from having the propeller disc offset from the rotational axis doesn't place bending loads on the hub. And obviously, the blades will be mass balanced to place the center of gravity at the hub axis.
I'll go out on a limb here and say that some genius figured out a way to reduce the horrific noise level caused by such a small propeller by having the blade tips each run in a slightly different path of rotation. Brilliant.
And here it is in action where the eccentric blade disc can be clearly seen.
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
$endgroup$
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
add a comment |
$begingroup$
You are right. They are unequal length blades. Schempp refers to the propeller as being "noise optimized" and you can see that the blades are free to flap (forward) like helicopter blades (which flap up) so that the asymmetric thrust axis from having the propeller disc offset from the rotational axis doesn't place bending loads on the hub. And obviously, the blades will be mass balanced to place the center of gravity at the hub axis.
I'll go out on a limb here and say that some genius figured out a way to reduce the horrific noise level caused by such a small propeller by having the blade tips each run in a slightly different path of rotation. Brilliant.
And here it is in action where the eccentric blade disc can be clearly seen.
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
$endgroup$
You are right. They are unequal length blades. Schempp refers to the propeller as being "noise optimized" and you can see that the blades are free to flap (forward) like helicopter blades (which flap up) so that the asymmetric thrust axis from having the propeller disc offset from the rotational axis doesn't place bending loads on the hub. And obviously, the blades will be mass balanced to place the center of gravity at the hub axis.
I'll go out on a limb here and say that some genius figured out a way to reduce the horrific noise level caused by such a small propeller by having the blade tips each run in a slightly different path of rotation. Brilliant.
And here it is in action where the eccentric blade disc can be clearly seen.
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
edited 2 hours ago
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
answered 5 hours ago
John KJohn K
33.5k1 gold badge58 silver badges110 bronze badges
33.5k1 gold badge58 silver badges110 bronze badges
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
add a comment |
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
May have something to do with unequal blades cancelling, rather than reinforcing, sound waves. Great answer and pic.
$endgroup$
– Robert DiGiovanni
5 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
They look like they are also unevenly spaced around the hub, which is a known technique to reduce noise. escholarship.org/content/qt9q75v9t9/qt9q75v9t9.pdf
$endgroup$
– MikeY
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
$begingroup$
@MikeY now that you mention it, yeah it's obvious when you look carefully.
$endgroup$
– John K
4 hours ago
add a comment |
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$begingroup$
Link? PS there is such a thing as a one-bladed prop with a counterbalance. Is there any counterbalance present anywhere on the prop you are speaking of?
$endgroup$
– quiet flyer
8 hours ago
$begingroup$
Going by the results of a simple image search, they look the same length. Unless you have a link to an image showing different lengths, I challenge the premise of this question.
$endgroup$
– AEhere
7 hours ago
$begingroup$
ditto-- I suspect there is a parallax issue with the image he was looking at
$endgroup$
– quiet flyer
7 hours ago
$begingroup$
They look to me of the same length (google.com/…)
$endgroup$
– Trebia Project.
6 hours ago