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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1answer
52 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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111 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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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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125 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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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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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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143 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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74 views

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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247 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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206 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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108 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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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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192 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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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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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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102 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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178 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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415 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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158 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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1answer
88 views

What is the definition of “geometric pitch angle” for a propeller?

My question is regarding the geometric pitch angle of a propeller. Is it the angle between the rotational/propeller plane and the zero lift line of the particular airfoil at a propeller section? Or is ...
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171 views

What are the design considerations for variable-pitch folding-propellers?

Folding props are increasingly used on self-launch gliders in order to reduce drag. Here is an example of 1m dia. props from LZ Design's FES system: For self-launch gliders, due to minimally-sized ...
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160 views

What are the advantages/disadvantages of a forward-folding propeller?

The AMS Carat A is a motorglider with a forward folding propeller. To my knowledge, this is the only production plane with this characteristic. The most popular self-launching gliders with front ...
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165 views

Why do the ratio of proppeler plane over jet engine seems to have change in Bucarest airport during the covid19 crisis?

I live in a village very close to an (intl) airport: Bucharest "Henri Coanda" International Airport. Now, due to lock-down caused by covid pandemic, I noticed - at least today when I spent most of the ...
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309 views

How can I calculate the relationship between propeller pitch and thrust?

I am trying to design a WWI propeller so I started calculating. The propeller comes with a specified pitch of 1.75m. The engine is supposed to run at around 1900 rpm and 147kW. These are most likely ...
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Why are highly cambered airfoils rarely used in propellers or wings?

Highly cambered airfoils like the Seligs and Epplers are hardly ever used in propeller or wing sections. Why? Does their performance reduce at high Re? Are they only adequate at low Mach, low Re? ...
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147 views

How big is the TP400-D6 turboprop installed on the A400M?

I am trying to re-create the A400M TP400-D6 engine in CAD, mainly the nacelle and propeller, yet I can't find any detailed dimensions for it. Europrop specifies a 0.92m diameter for the TP400-D6, so ...
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235 views

Was Ludwig Wittgenstein's aircraft propeller ever built?

Ludwig Wittgenstein designed (and received a patent for, at the remarkable age of 22) an aeronautical propeller. Wikipedia describes it: Wittgenstein’s design required air and gas to be forced ...
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338 views

Manifold pressure vs rpm vs power obtained and more about 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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917 views

Manifold pressure vs power vs rpm

From what I know MAP is a way of measuring engine power with variable pitch propeller. Greater throttle setting - greater power - greater MAP on the gauge. It happens because MAP is in fact vacum ...
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360 views

What are the aerodynamic design principles behind the “supersonic” propeller of Luigi Colani's C-309 racing plane?

One of Luigi Colani's designs that is particularly confusing to me is the second design iteration of the C-309 propeller racing airplane. Allegedly, its two propellers are designed to be supersonic ...
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Why don't NK-12 powered contra-rotating propellers turn in equal rpm?

The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. The NK-12 drives two large four-bladed contra-rotating propellers, 5.6 m (18 ft) diameter (NK-...
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939 views

How does Propeller windmilling work?

I’ve got a problem with understanding propeller windmilling. What I know is that when rpm are low and tas is high the blade aoa goes „over” the blade and is some kind of negative now, producing thrust ...
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How does the DA 40 NG automatically control the mixture, pitch and power by just providing one throttle?

I'm a student pilot and here at my school we have the older gen DA40s which have individual lever for mixture, pitch and power. I was looking at this video of the DA40 NG, and got quite curious as ...
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Could propellers benefit from the design of the Blue Edge rotor?

Source: wired.com If indeed the Blue Edge blades reduce noise by 50%, could the similar design be used on [forward-facing] propellers without a penalty in speed or agility?
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How is d(Cl)/d(alpha)@stall and Cl increment to stall defined in Xrotor?

I hope there are some people around here with some experience in Xrotor than me. (Xrotor is:"XROTOR is an interactive program for the design and analysis of ducted and free-tip propellers and ...
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275 views

How much actual difference does fixed pitch propeller make in takeoff distance?

So it's possible to buy fixed pitch propellers which are either optimised for takeoff or for top speed. I guess most airplanes have a compromise. Considering a training aircraft like a Cessna 152, ...
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Do Constant maximum lift to drag ratio variable pitch propeller exist?

Are there variable pitch propellers, where pitch is set so that the blades constantly are at their maximum lift to drag ratio AoA, whatever the incoming relative wind speed & direction? Such a ...
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Supersonic propellers for supersonic aircraft? [duplicate]

A propeller is a spinning wing. Supersonic wings work. So, provided that the blades are made wide-chord and thin like supersonic wings are, with a supersonic airfoil, can they not power efficiently a ...
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2answers
141 views

Does counter-rotating propellers on multi engine airplanes have critical engine?

I read from most of the article and books that counter-rotating propellers multi engine airplanes do not have critical engine, but it just happened to my friend who did his Commercial Multi Engine ...
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231 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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What instructions should I give to an untrained passenger for Hand propping Cessna 172N as a pilot?

Does anybody know what is the most effective way of hand propping a Cessna 172N, with a passenger who is not mechanically inclined. So you need to give them the most easy to follow and simple ...
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What is the effect of moving a propeller closer to a wing?

Does it improve efficiency? What if the wing is just a plate? Certainly increasing plate thickness will decrease efficiency.
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Can someone please tell me all the units for the propeller thrust equations?

This answer is excellent:- Is there any equation to bind velocity, thrust and power? except that it is (in practice) unusable, since all the units are missing. I'm guessing we use meters for length ...
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204 views

Which type of fan is better for wind tunnel testing?

I would like to build a small wind tunnel to test a miniaturized wing/airplane. I have two options, using axial blower (picture 1) or using centrifugal blower (picture 2). The first will be the wind ...
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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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What is a good and simple software for calculating propeller thrust and required power?

My main requirements: Calculate propeller thrust with big range of the altitudes (0 - 200 km) or to have air pressure input parameter, which I can type. For example pressure for 152 km is $4.98\...
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607 views

What is the purpose of the propeller?

The propeller generates thrust, but what is the purpose of thrust of propeller? Is it to help the aircraft move forward or to produce lift to rise up?
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137 views

Which is better: a rotor / prop followed by a stator, or contra rotating rotors / props?

It is all in the title. I'm interested in power absorbed/used for a given thrust, or thrust generated for a given power (same diameters of course). Just thrust and power. Ignore materials, electric ...
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308 views

Do ducted fans have a future in forward flight aircraft? Can they be made more efficient than open rotors?

I'm fascinated by how ducted fans have the ability to be more efficient than open propellers of equal diameter in vertical flight through the use of tight tolerances, lightweight duct material, proper ...

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