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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6
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1answer
1k 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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3answers
222 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
131 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
63 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
44 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
170 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
22 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
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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 ...
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4answers
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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
54 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
207 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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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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1answer
138 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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2answers
346 views

Does a constant speed prop maintain the optimal angle of attack at all time?

From an answer on this site: The governor just knows: Speed too fast, flyweights move out, routes pressure to move the blades more coarse; speed too slow, flyweights move in, routes pressure to move ...
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2answers
112 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 ...
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2answers
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What is the physical difference between an airplane having let's say 150 horsepower to an airplane having 250 horsepower?

I was wondering what defines horsepower in an airplane piston engine and how can it be changed?, is horsepower changing during flight?
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1answer
68 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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3answers
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Is high propeller pitch inherently inefficient?

For an airfoil, in general, the aerodynamic force is more or less perpendicular to the chord line. A low-pitched propeller blade has it's chord line more perpendicular to the direction of flight, ...
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1answer
94 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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1answer
83 views

Help in understanding this velocity triangle of a propeller

I was reading a research paper and have had difficulty understanding something. How did the author get tan(phi) in these terms? This is something I've been trying to figure out for a long time now.
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Relationship of propeller RPM, blade pitch, and drag at very low blade pitch angles

I'm researching the 2016 crash of a PIA ATR-42 in Pakistan, the report on which was recently released. Link to the report: https://www.caapakistan.com.pk/Upload/SIBReports/AAIB-386.pdf During the ...
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7answers
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How much do propellers stutter?

A photo in EAA's monthly magazine shows one propeller blade as a dozen distinct images rather than the usual smooth motion blur. One explanation (this answer appears to have been deleted) for this is ...
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2answers
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Will the blade angle of a constant speed propeller be at its least angle (fine pitch) during full throttle and prop full?

During low power settings, low throttle setting and prop full during taxi, the blade angle will be at its finest pitch. As we increase the throttle for take-off, will the blade angle remain in its ...
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2answers
116 views

What is a typical compression ratio in light turboprop aircraft propellers? [closed]

Does anyone happen to know a rough estimate of a typical light turboprop aircraft propeller's compression ratio? Something with 6-12 seats like a Cessna Caravan or Piper Malibu. Doesn't need to be ...
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Why does a shrouded propeller have a lower downstream velocity than an unshouded propeller?

Why does a shrouded propeller have downstream velocity $V_3 = V_0 + w$, while the unshrouded propeller has a velocity $V_3 = V_0 + 2 w$? What are the reasons of this difference? $ \begin{align} w &...
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171 views

How can I find the maximum climb angle of a propeller driven aircraft from a graph of vertical velocity against airspeed?

I've been asked to find the maximum climb angle of a propeller driven aircraft from the graph of vertical velocity against airspeed: How can I do that?
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1answer
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Why aren't thermal analysis of propeller done?

I have searched for articles on Thermal Analysis of Propeller but couldn't find one. Can I assume the aircraft company don't perform heat transfer simulation and analysis of high speed propeller? Isn'...
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6answers
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What other advantage(s) does an adjustable prop give you?

From what I understand, the purpose of a variable-pitch propeller (be it manually adjustable, or constant speed) is that it allows the engine to always operate at its most efficient speed, much like ...
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5answers
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Do jet aircraft have a better glide ratio than propeller aircraft in general? If so, why?

Being fond of aviation, I play with software simulators a lot. I have noticed that while jets seem to be able to glide for a long distance even at zero throttle, propeller aircraft need to be ...
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1answer
118 views

How can a small ducted fan produce a large amount of thrust?

This 15.2 cm ducted fan by Schuebeler can produce 175 Newtons of static thrust. How is this possible in such a small diameter? If this seems normal, then why and how can this ducted fan produce that ...
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1answer
259 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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Is “V/n” geometric or effective pitch in advance ratio formula?

V is the freestream fluid velocity, typically the true airspeed of the aircraft or the water speed of the vessel n is the rotational speed of the propeller in revolutions per unit of time D is ...
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1answer
122 views

Is flow attached at fixed propeller blade at every RPM / speed conditions?

Propeller blade AoA depends on tangential veloctiy caused by rotation and forward speed "head wind". If propeller has fixed pitch is flow attached on blade at every RPM / speed conditions? ...
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2answers
291 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. ...
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1answer
141 views

Does ducted fan require more engine torque than unducted-fan,at same RPM?

Two identical fans, one is unducted and other is ducted,both operate at same RPM. •Does ducted fan require more engine torque than unducted-fan ,measured both at same fan RPM? power=torque x RPM so ...
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0answers
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In actuator disk theory, why does changing the inertial reference frame work for Bernoulli's equation?

I was reading this website: https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html, which goes over actuator disk theory, and it discusses using Bernoulli's equation in a frame of ...
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5answers
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Could propeller wash provide sufficient lift to take off - even in theory?

I know this seems a crazy thing to ask but it is not the same as lifting oneself by the bootstraps. If you try to lift yourself that way, there are two equal and opposite forces, yet there are ...
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2answers
217 views

Does propeller size affect total drag force of plane?

Integration of pressure distribution of each blade get net force(thrust) which is allways pointing forward.So there is no drag force at any propeller ,that tells that size of propeller doesnt ...
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2answers
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Clarification on autogyro thrust formula

I'm slightly confused regarding the formula quoted here: How to calculate the amount of thrust of a autogyro during auto rotation? When they say thrust is equal to the weight. Do they mean use earth ...
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1answer
282 views

Are the A400M propellers rotating in the wrong way in “Mission Impossible: Rogue Nation”?

At the beginning of the movie Mission Impossible: Rogue Nation we can see an A400M taking off. When the engines start, the propellers turn in opposite directions. As I understand it this is not a ...
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2answers
234 views

Does a constant power prop exist? What are the tradeoffs compared to a constant speed prop?

Variable-pitch props allow pilots to adjust the angle of attack of the propeller to change the load on the engine. The most common implementation of this is a constant speed prop where the prop ...
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1answer
148 views

How does 'standalone' propeller efficiency change with altitude?

I've seen questions regarding propeller aircraft and altitude and their interaction. But I'm wondering what the relationship between just the propeller and altitude (changing air density) is. How does ...
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1answer
80 views

Is propeller wake turbulence quantifiable based on operating conditions?

I know the propeller does work on the air and thus the flow behind a propeller is higher than the airspeed. However, what is the quality of this flow? If I were doing a heat transfer analysis of an ...
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1answer
213 views

How can jet engines be more efficient than propellers? [duplicate]

If jet engines are smaller in diameter than propellers, is it fair to say that propellers accelerate a lot of air a little while a jet engine accelerates a little air a lot? Basically, a jet engine ...
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3answers
4k views

In an engine failure, should I expect less range than with the engine in idle?

I fly a C172 (fix pitch propeller) and when my instructor and I practice a simulated engine failure, we do not turn off the engine, instead we set the engine to idle. In an actual engine failure, ...
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2answers
121 views

Do the blades of the rear disk have different geometry to the blades of the front disk on a contra-rotating assembly?

If my understanding is correct, the air flow is accelerated by the front propeller toward the rear propeller in a contra-rotating prop assembly. Therefore, the rear disk would be receiving air at ...
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2answers
184 views

Why does disk loading mean anything when rotors/propellers are not disks?

"The helicopter rotor is modeled as an infinitely thin disc with an infinite number of blades that induce a constant pressure jump over the disk area and along the axis of rotation." This is ...
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2answers
395 views

How does the location of a propeller affect an aircraft's stability?

Some aircraft possess propellers on front of the fuselage, like the Cessna 172, and some aircraft have propellers located at the rear of the fuselage, like the Velocity 173RG-E. How does the ...
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3answers
499 views

How do propeller planes sync their propellers?

While reading this question, I found that the answers did not address the point I had come for. On planes with electronic propeller synchronization, how is it actually accomplished? I know why ...
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3answers
185 views

Are there any aircraft powered by tip jets in the propeller blade?

I am familiar with tip jet powered helicopter experiments. Is there any aircraft that use/used this mode and would it be useful to use a tip jet driven prop on aircraft instead of piston or turbine ...

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