Questions tagged [propeller]

Aircraft propellers are airfoils which convert rotary motion from a piston or turbine engine into thrust suitable for propelling an aircraft.

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4
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2answers
396 views

How to calculate the efficiency of a rubber powered propeller

I made a simple test rig together with a stopwatch to measure the thrust (in grams) with respect to time of a rubber powered propeller. This enabled me to compare the performance of different ...
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2answers
1k views

Why, with a constant speed propeller, does moving the propeller control forward increase drag?

Could someone explain why, let's say in a constant speed propeller, with moving propeller control forward the drag increases? It is noticeable when we push the blue knobs forward in flight that the ...
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12answers
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Why are push-propellers so rare, yet they are still around?

Jet engines are by their very nature push-engines, however, most propeller airplanes use pull-engines. Is there an inherent advantage to using pull-propellers except for the increased airflow over the ...
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2answers
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Why does a low pitch propeller have better acceleration/take-off and climb characteristics than a high pitch propeller?

Why does a propeller with a low pitch have better acceleration/take-off and climb characteristics vs. a high pitch propeller? And conversely, why is a propeller with a high pitch not as good during a ...
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1answer
184 views

Why does a force on a propeller act 90° “ahead” due to gyroscopic precession?

This is a common explanation: A tailwheel airplane is on the takeoff roll and the tail comes up, the propeller disc rotates forward. That's akin to someone pushing on the top of the disc. The force ...
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1answer
275 views

What factors determine magnitude and orientation of induced velocity at propeller blade?

• Magnitude What factors determine magnitude of "Vind" (induced velocity)? • Orientation If we take analogy with induced velocity at wing,isnt "Vind" must be prependicular to Vr? • ...
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9answers
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Were propeller airplanes significantly more “scary” to fly in compared to modern jet ones?

I've flown exactly once in my life. It was in 2004, with a commercial jet. Not a "jumbo", but a normal-sized jet plane in common use for cheap flights in that year. (Well, twice if you ...
14
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4answers
9k views

Why does the Cessna 172S Skyhawk use only two blade fixed pitched prop?

Surely it would get more thrust from a three blade variable pitch propeller. From what I've read it's all about the area swept and also should be far enough apart to not cause too much interference. ...
4
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1answer
311 views

What is the difference in performance between variable pitch prop and two fixed propellers for take-off and cruise speeds?

Push-pull configuration aircrafts usually feature identical engines and propellers working only in tandem for multiple reasons like higher speed, better climb rate, reliability, cost, ease of ...
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1answer
2k views

How do witness marks on propeller blades provide data on estimated blade angles at the time of impact?

In the NTSB Powerplant Group Chairman Factual Report for the 2014 crash of the King Air B200 in Wichita Kansas (NTSB# CEN15FA034), I read: "Neither propeller was feathered before impact. Both ...
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2answers
128 views

How would flow angle change along the length of a propeller airfoil?

Let's assume I have: windspeed of 15 m/s blade length of 10 m rotational speed of one revolution per second Can someone please help me calculating how the flow angle would change along the length of ...
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1answer
106 views

What is the certification process for a new propeller blade design?

I am wondering whether a propeller blade design (say from Hatzell) is submitted to a specific agency for testing and approval, and if these designs are then registered. Looking through Hatzell's ...
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2answers
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What are the advantages of the NASA LEAPTech propeller on wing technology?

NASA has detailed experiments with a new type of parallel array of small electric propellers on the leading edge of the wing technology that they are calling LEAPTech. The press release notes that ...
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0answers
54 views

Calculating the Thrust vs RPM Relationship of a Brushless DC Motor

hope everyone is doing okay. I am conducting a project with my friends for an Unmanned Aerial Vehicle. We are first using MATLAB - Simulink to design and simulate the quadrotor. We completed the ...
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1answer
91 views

How to do blade element momentum theory analysis for different geometries of airfoil, e.g. NACA airfoils?

I want to analyse NACA airfoils using BEMT. I have only yet done it for basic symmetric airfoils. I would like to know what all assumptions remain same in NACA airfoil analysis and to what degree it ...
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4answers
2k views

Why aren't large, low-speed propellers widely used?

I am trying to calculate different propellers for the simple case like helicopter moving slow up like 1 m/s or staying/hanging in one place. From generic physics point of view it is more efficient to ...
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1answer
2k views

What is this four-engine propeller airplane?

I came across this print at a bargain store a couple weeks ago. At first I thought it might be a variant of a Lockheed L-188 Electra; then I noticed that it has at least 6 engines, as the print ...
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1answer
180 views

Would large, low aspect ratio fan/propeller blades be more efficient? Why not?

With reference to this answer We read in the above that accelerating a larger mass of air by a smaller amount is (theoretically) more efficient. This is an advantage of a larger propeller than is ...
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2answers
135 views

In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?

Assume I am flying straight and level with power setting 21 inches of MAP and 2300 RPM with TAS=100 kts, now I change my Prop lever only (MAP = no change & TAS = no change) from 2300 to 2500, ...
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3answers
954 views

What is the relation between manifold pressure, RPM, and power, in a constant speed prop?

I know that there are similar topics here, one is mine even, but still I have few questions about constant speed propeller. My questions: Why if we decrease RPM and maintain throttle lever setting ...
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2answers
707 views

How will a variable pitch propeller move during takeoff?

In my ATPL books i've learned that for a variable pitch propeller, it is better to have a fine pitch for take-off (higher RPM) and a coarse pitch for cruise (lower RPM). In this question taken from ...
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1answer
1k views

What are the black boots on this Extra 300's prop?

I normally think of black boots on a prop as being for de-icing. However, the Extra 300 is not suitable for known-icing conditions, or even IMC flight. (It's AFM says "Only VFR flights at day are ...
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0answers
38 views

Is pitch-flap coupling an aerodynamic effect or an intrinsic property of a delta 3 offset?

I am modelling a propeller, in particularly the equations of motion of the various pitch/lag/flap angles as the propeller is turning around. The blade includes a $\delta_3$ angle, which provides pitch-...
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1answer
1k views

Is this equation for propeller thrust correct?

From dimensional considerations, and assuming that the power $P$ applied to a propeller of diameter $D$ moving at an axial speed $V$ is 100% converted to the acceleration of a mass of air with density ...
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2answers
167 views

Why does propeller slip (efficiency) change during the flight (fixed-pitch)?

I was wondering how the efficiency of a fixed-pitch propeller changes during different stages of flight and why it does so. I suppose when we are talking about propeller efficiency we are actually ...
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3answers
33k views

How high can propeller airplanes fly?

Is there a maximum height a propeller airplane could fly? Some lower bounds for maximum flying altitude: 12,000m (39,370ft): Antonow An-70, produced 1994 12,310m (40,387ft): Lockheed Martin C-130J ...
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2answers
161 views

How do electric propeller governors (or electrically controlled governors) work and what are their pros and cons?

I am trying to understand why electric propeller governors are not (yet) prevalent given that they offer the ability to control the RPM with high accuracy. What is the typical architecture for an ...
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1answer
56 views

How to decide the diameter of a propeller and number of propellers needed in a UAV I am designing? [closed]

I want to design a turboprop aircraft. I know all the design parameters such as lift, thrust, weight etc at a given flight stage. I want to know what the size of the propeller should be.
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12answers
13k views

Why does flight training usually start with (unsafe?) propeller planes and not with (safer?) jets?

I live in the UK and would like to learn flying jets, but most courses seem to start with propeller planes. Not sure if this might be a misconception about the safety of different aircraft types, but ...
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2answers
7k views

What are the pros and cons of scimitar propellers?

I know scimitar propellers are used to reduce noise, but what is their downside? There has to be one, considering most propellers don't use that shape.
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5answers
951 views

Why does this calculation show Gustave Whitehead's propellers were more than 100% efficient?

I have tried to calculate the efficiency of Gustave Whitehead's propellers using the information he provided to the American Inventor Magazine in 1902 (see the citation below). Number of propellers = ...
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2answers
13k views

What is the correct formula to calculate propeller efficiency?

How to calculate in the right way the efficiency of a propeller? If we know the engine power, speed of the plane and the thrust of its propeller, what is the correct method, (1) or (2), for ...
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5answers
8k views

Would connecting propeller blades with a continuous ring reduce induced drag?

Turbine engines are covered, which of course is to contain the process (just like a super/turbocharged engine is as soon as the air enters the intake). But it got me thinking, doesn't this also reduce ...
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0answers
70 views

Calculate propeller efficiency [closed]

I have a test bench that can test the thrust of a propeller with my electric motor, is there a way that I can calculate the propeller efficiency (ηp)?
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5answers
1k views

Do contra-rotating propellers have the same RPM?

Image source Here is a contra-rotating propeller. The front propeller rotates counterclockwise while the back propeller rotates clockwise. My questions are: Do they rotate at the same speed (RPM)? ...
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4answers
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Would a coaxial propeller with the second prop slower and larger improve speed?

Looking at various propeller designs, I started wondering about these limitations: Large propellers at high speeds have tips going supersonic Scimitar props attempt to keep prop tip from going ...
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1answer
2k views

Why do propellors have white markings on their tips? [duplicate]

Why do propellors have white markings on their tips? Here are a couple of examples:
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2answers
2k views

How much thrust is gained from placing a propeller in a duct?

Assuming that the power and diameter are the same, how much extra thrust can be gained by placing a propeller in a duct? How does it influence the RPM? To clarify: take any prop, place it in a well-...
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3answers
245 views

Would it be beneficial to have rotors AND propellers instead of a tiltrotor?

Would it be beneficial for tiltrotor aircraft if they had BOTH rotors and propellers, instead of the hybrid proprotors that are neither good propellers nor good rotors? Like imagine the V-22 Osprey ...
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1answer
152 views

Fly a fixed wing single propeller airplane like a helicopter?

Has anyone tried to "helicopter" an airplane? And succeeded? And posted this video on the internet where I can find it? What I'm talking about with what I would call a "helicopter&...
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1answer
158 views

What is the difference between RTOP, MTOP, and MCP?

I am currently learning how to fly the SD3-60 (Shorts) Aircraft, and I am trying to gain an understanding of RTOP (reserved take off power), MTOP (max take off power), and MCP (max continuous power). ...
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1answer
75 views

Retreating Blade Stall, P-Factor, and Gyroscopic Precession

Most airplane pilots are aware of P-Factor in propeller driven aircraft and that it tends create a torque in phase with the lift imbalance over the blade disc, resulting in a yaw moment about the ...
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2answers
179 views

What are the pros and cons of putting a propeller immediately before a slipstream pylon vs. immediately after

In the following situation with a slipstream pylon for a self-launching glider, what are the tradeoffs in sticking the propeller before vs. after the pylon? The wind turbine industry has the same ...
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0answers
34 views

Comparison of specific thrust vs. speed, for EDFs and propellers

I stumbled upon this graph showing the decrease in specific thrust (Thrust by Power) in relation to velocity, for a Schuebeler EDF: https://www.researchgate.net/figure/Specific-thrust-T-P-vs-airspeed-...
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3answers
3k views

Is possible to stick two '2-blade' propellers to get multi-blade propeller?

Does propeller blades' airflow interfere with each other blades and decrease overall thrust? Should I consider high pitch propeller for this purpose? My purpose: I'm looking for a 20-inch four-blade ...
9
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4answers
2k views

If an elliptically-shaped aerofoil gives the optimum lift distribution, why aren't propeller blades designed around this ideal?

So given an elliptical lift distribution is the most efficient, why are propellers not designed around this? Props aren't affected by the adverse stall characteristics that concern a "main", ...
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1answer
100 views

For a same propeller solidity, what are the tradeoffs between blade activity factor and blade number?

In order to absorb more power for a given prop diameter, we can design the propeller with a higher activity factor-- basically what amounts to wider blades-- or we can also design it with more blades. ...
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1answer
275 views

What is the result of increasing number of propeller blades on the same engine [duplicate]

For example Rotax 912. We can meet this engine with 2 and 3 propellers mounted. Or compare airplanes equipped with engines with pretty the same power output i.e. C152 with Lycoming O-235 - 110 HP and ...
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7answers
37k views

Why do most single propellers have a clockwise rotation?

Why do most single propellers have a clockwise rotation (seen from the pilot's point of view)? There are though multi-engine planes that have each propeller rotating different directions, but in the ...
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1answer
85 views

Deicing Rod for Propellers

Similar to a card hitting the spokes of a bicycle, the card is soft enough to knock the dust off the spokes with no damage. What material would be best to impede the propellers to chip off the ice. ...

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