Linked Questions
14 questions linked to/from Why don't aeroplanes use propellers with more blades like the intake on a fanjet?
25
votes
7
answers
9k
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Given the same engine, why install a gearbox on a turboprop but not on a turbofan?
I am reading the book Mechanics and Thermodynamics of Propulsion, by Hill and Peterson. I found out this image while reading the chapter 5, "Thermodynamics of Aircraft Engines":
Why would there be a ...
- 1,027
28
votes
2
answers
36k
views
What are the advantages of more than 4 propeller blades?
I have heard that propellers with more than four blades are not as efficient as 4 or less blades because of lower thrust which may result from interfering prop-streams. But I see the ATR-42/72 and ...
- 11.3k
35
votes
5
answers
17k
views
How does a fan differ from a propeller?
Why is the fan in a turbofan different than a propeller in a small airplane? Why do propellers typically have 2 or 3 blades, but the fan has a lot more? And why is the fan shrouded but the propeller ...
- 1,059
20
votes
4
answers
9k
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Why are three-bladed helicopters relatively rare?
I admit that this observation is entirely subjective, but it seems to me that there three-bladed rotors are significantly less popular than two or four.
Factors that I'm guessing contribute -
...
- 9,461
26
votes
2
answers
8k
views
Is it possible to fly with counterbalanced single blade engines?
Refer the image for counterbalanced single blade (Source http://www.aviastar.org/helicopters_eng/bo-103.php).
In ground school, they took us for aircraft inspection at end of our ground school ...
- 1,922
20
votes
2
answers
14k
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Why are there so many different propeller shapes?
While doing an image search, I found these images of propellers:
and
Some appear to be straight-ish on the leading edge and curved on the trailing, some curved on the leading edge and straght-ish on ...
- 10.9k
9
votes
3
answers
5k
views
How does blade solidity ratio relate to thrust/power/torque of a propeller?
for quite some time I was using ABBOTT formula for static thrust estimation on a two-bladed propellers:
$$
T=6.8\times10^{-5}\times D^{3}\times p\times RPM^{2}
$$
$T$ is Static Thrust (N); $D$ is ...
- 611
12
votes
2
answers
3k
views
Why is the bypass ratio of a turboprop higher than turbofan?
Whenever, I come across turboprop, the author always mentions that they have higher bypass ratio than turbofan but no one explains the reason for this.
So, is the bypass ratio higher due to higher ...
- 731
3
votes
2
answers
2k
views
Why does a hovercraft lift blade look one way, but a propeller another?
The lift blade of a hovercraft looks like this:
Note the ten rectangular blades.
The blade of a propeller-craft looks this this:
Note the three, traditional airfoil-shaped blades.
Why are the two ...
- 131
0
votes
2
answers
2k
views
What is engine power vs propeller thrust relation?
Given:
speed 30 knots
engine power 70 hp at 5800 RPM
propeller 3 blades, diameter 14 inch, pitch 17 inch, at 2300 RPM
fluid density 1023 kg/m3
I know that each blade is basically one wing. ...
user52248
5
votes
2
answers
900
views
Do any propellers/propfans use stator vanes? Why is this not a commonplace feature?
I understand that axial-flow turbine engines generally include stator vanes behind every(?) compressor and turbine stage. This makes quite intuitively sense, because without them the rotating blades ...
- 743
4
votes
2
answers
308
views
How does one choose the number of blades and the diameter required for a turboprop propeller?
I am interested in the preliminary design of a regional aircraft that uses turboprops as the propulsion method.
Following considerable research online about propeller design (disk theory, BEM...) I am ...
- 45
1
vote
2
answers
158
views
This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff [duplicate]
This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff.
But for this example the engine is secured to a test mount, and under "full throttle", the thrust ...
- 11
0
votes
0
answers
114
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Why does adding more blades to a propeller/fan not show a decrease in efficiency?
According to this answer increasing blade solidity increases the blade area by either enlarging chord or increasing blade count both of which reduce efficiency via reducing the lift coefficient and ...
