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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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quadcopters — should the propellers/motors all be at the same height

In quadcopters (or in any other drones), must the propellers/motors all be at the same height, or can there be symmetric height differences (like for eg, two of the motors at the "back" are elevated ...
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1answer
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Which one will be louder: a turbofan or a contra-rotating electric propeller engine, if both are of comparable thrust? [on hold]

If we have two engines that produce similar (to identical) thrust, the first being a classical turbofan and the other a contra-rotating unducted electric prop-engine, which will be louder.
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How to compute actuator torque requirement for Variable pitch mechanism??

Suggest me any reference to compute the torque requirement for actuator/motor to control the pitch angle of propeller (Variable Pitch Propeller). Thanks in advance Arun Ravindran
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1answer
219 views

What are these small propellers in the A330 MRTT's wings?

In actual flight there are small propellers rotating at the front of these "pillars". What are they? They are visible in this video.
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1answer
86 views

What is the Efficiency of Cessna-150's Propeller?

From that Cessna-150's data, it used Continental 0-200-A 100 HP (75 kW) at 2,750 RPM and with Fixed Pitch propeller with its diameter=69 inches. If power is delivered maximum to the propeller (through ...
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2answers
156 views

Must quadcopters have the same propeller sizes?

I was flying quads today and it just suddenly popped up into my mind — do the propellers all have to be the same size in quadcopters? Mine are, but What if two propellers were larger and the other two ...
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2answers
182 views

Does RPM refer to the speed of the engine or the speed of the propeller?

I followed discussion here: In a constant speed propeller, why does the RPM drop with a prop pitch increase?, I got confused about the RPM there. As the opening statement said in that discussion, "...
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Does shrouding a propeller minimize induced drag by equalizing the downwash velocity along it's blades?

EDIT: It's not a duplicate of Are ducted fans more efficient? That question and the answers doesn't address the reason for the higher theoretical efficiency, it is more about efficiency in practice (...
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Does Froude Efficiency represent an upper bound for propellers in certain flight / aircraft conditions?

I used the Simple Propeller Theory to calculate the Froude Efficiency for my theoretical propeller-driven craft (at 65k feet). Here are the results: https://ibb.co/kPPqzU. My results were that, for ...
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2answers
72 views

How is a propeller diameter for given application determined?

let's say I need 1000 N of thrust for a given aircraft and flight velocity. I have available a fixed pitch propeller with a given shape, and thus given performance to advance ratio curves. Let's say ...
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2answers
75 views

Propeller Characteristics at Different Altitudes

Assuming I have a propeller with a given diameter (D), pitch, blade twist, and number of blades, I can theoretically analyze discrete airfoil sections in XFOIL and come up with lift and drag polars ...
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1answer
111 views

Propeller Efficiency calculation different by two methods

Please refer to this MIT page which I used for my calculations: https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html I calculated my aircraft propeller's prop, thrust, and torque ...
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4answers
232 views

Does the required torque to spin a propeller increase with RPM?

I‘ve currently been experimenting with different propellers: 12x12 prop, 16x12 prop (both two blades) and a 22x14 (6 blades) prop. They were propelled by a 2.4 kW electric motor with 260 kV on a 6S/...
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6answers
212 views

Is precession a problem for two-bladed propellers?

The vast majority of wind turbines are a three-bladed design. Although two blades would be more efficient, two-bladed designs are more likely to suffer from precession. Do two-bladed propellers suffer ...
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3answers
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Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
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1answer
150 views

How does the load transfer from a prop to the airframe?

I was just watching this video... Restoration and startup of a Wright 1820 Cyclone ...and it got me thinking: a propeller shoves back air, and this creates a forward force on the prop. The prop ...
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0answers
71 views

Propeller air displacement

I was thinking about propeller design just now and it came to mind that, theoretically, the air displaced by the propeller after every rotation might not be able to "flow back" into the area "served" ...
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3answers
268 views

Why are helicopters less efficient than planes?

At higher speeds, advancing helicopter blades will operate at velocities approaching mach 1, reducing efficiency. But what about lower speeds? A helicopter is basically a wingless plane with a giant ...
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1answer
116 views

What would happen if blades are not pitched correctly on a propeller blades? [closed]

What would happen on a 6 blade propeller if each blade opposite another was pitched in completely the opposite direction.
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1answer
159 views

How much thrust could a 400 mm EDF produce?

there's a 195mm EDF from Schübeler that produces 25 kg of thrust at a peak power consumption of 15 kW: https://www.schuebeler-jets.de/de/produkte/hst Now, my question is: How much thrust could you ...
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1answer
180 views

Why divide the blades of a 9 blade propeller into 3 groups?

In a youtube video an airboat is featured with two contra-rotating propellers, each holding nine blades. Interestingly those nine blades are not spaced evenly, but grouped into three groups. I've ...
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1answer
173 views

How do you maximize an electric engines thrust?

I‘ve been recently looking for answers to this question on the internet but the jungle of propellers, fans and electric motors didn‘t quite get me an anwer. How would I have to design an electric ...
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1answer
118 views

What are dimensions of the B-17 propellers?

I'm curious about the aerodynamics of the Boeing B-17 propeller, as the proportions looks perfect for a project I'm working up. Does anyone out there know where to find the specs/dimensions/models for ...
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0answers
184 views

How are the Tupolev Tu-95's blades shaped?

The Tupolev Tu-95 "Bear" seems like an awfully cool piece of innovation with its unusual contra-rotating supersonic-tipped props. From what I've been reading it sounds like it's been the only mass ...
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0answers
144 views

Will leaving the ducting on the propellers attached to a DIY aircraft give it more thrust? [duplicate]

I'm not sure if its the right place, I have a problem with a flying thingy, and you like flying thingies, don't you? I will be trying to add some means of propulsion to my friend's styrofoam plane (...
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0answers
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How does a partially covered air intake affect the thrust of a propeller ?

does a partially covered air intake of a ducted propeller significantly affect its thrust? If so, will it be like 10 or rather 90 percent less thrust ? Thanks for your answers! Simon
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2answers
133 views

Can lift be equated to how much air is moved?

The explanation for lift that I find easiest to visualize is that air is deflected downward by the wing. This downward action causes an equal and opposite reaction of an upward force against the plane,...
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2answers
76 views

How does radius of a propeller affect its performance?

Let's say we have a conventional two-bladed fixed-pitch propeller. All things being equal, would the same propeller but with half the size -- 50% radius, have 50% of the performance of the first ...
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0answers
42 views

How does the number of blades affect the static thrust of a propeller? [duplicate]

Since I couldn‘t find an answer to this question I thought I‘d ask you guys! By which factor does the thrust of a propeller increase if I double the number of blades, the motor being powerful enough ...
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2answers
520 views

Is 1 propeller always more efficient than 2?

Based on other answers I've read here (1) (2) (3), a single large blade propeller is the most efficient type of thrust you can get. There are 2 reasons for this (as I understand it). Firstly, ...
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2answers
944 views

Is it harmful to operate an engine “over square”? [duplicate]

Never Fly Your Engine "Oversquare!" is an old recommendation. This wisdom cautions pilots that selecting a power setting with a manifold pressure in inches higher than the RPM in hundreds is damaging ...
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1answer
303 views

What‘s the thrust of two stacked propellers?

Let‘s say that you have two identical propellers and each is powered by their own motor and together they produce a thrust of 1 kN. How does the thrust change if instead of operating them side on side ...
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1answer
144 views

On a ducted propeller, how does duct length affect thrust?

So if we are looking at an aircraft with a ducted propeller (or a high bypass turbofan engine), does it matter how long the duct is? As an extreme example, would having a duct that extends 100 feet ...
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3answers
433 views

Did WW2-era aircraft have constant-speed or variable-pitch props?

This is slightly related to my other question on variable-pitch controls. I want to know if WW2-era aircraft typically had variable-pitch or constant-speed propellers. Variable-pitch lets the pilot ...
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1answer
140 views

How did the controls work for variable-pitch props?

Variable-pitch propellers date way back to the 1930's and even earlier. I would like to know, what kind of controls they used? Some kind of lever or crank? How heavy were these controls? I'm thinking ...
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3answers
346 views

What is a biplane propeller and how efficient is it?

Lazair ultralight series II used biplane props to absorb more power from the engine....so my question is what really is a biplane propeller and are they efficient in comparison to a four bladed prop?
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Why are there extra restrictions on constant-speed propellers?

Constant-speed propellers are far more efficient than non-constant-speed propellers, allow the engine to be made considerably simpler (due to removing the need to continuously adjust the ignition ...
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1answer
88 views

Propeller Curve Modification on Test Rig

this is my first stack exchange question so please bear with me if I have missed a rule: I tried searching for this question to no avail. I have an off-the-shelf propeller for the purpose of eventual ...
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1answer
171 views

Why don't the ATR 42's propellers start/stop rotating simultaneously?

Why is it that for the ATR 42 one of the propellers begins to rotate before of the other? I've noticed that they also stop rotating at different times. Is there a reason for that or is it just for ...
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1answer
143 views

Why autogyros use pusher-, whereas, piston-engined planes use puller-configuration?

I found that most modern gyrocopters use a pusher-configuration, whereas, most piston-engined planes use puller-configuration. Since the pusher-configuration has major disadvantages, are there ...
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0answers
134 views

Why don't helicopter rotors use curved blades? Curved from the top view. [duplicate]

I'm studying blade element analysis and I tried applying it to curved rectangular blades instead of straight ones. It doesn't really show any significant changes in the inflow ratio computation. Why ...
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2answers
410 views

Pros and cons of a pull-push propeller configuration [closed]

What are the pros and cons of a pull push propeller in comparison to a counter rotating propeller?
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2answers
546 views

How to realistically model propeller static thrust?

I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and ...
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2answers
169 views

How long does it take for a propeller engine to spool-up?

To build further upon the question Why does a turboprop lag?, the following: Assuming a propeller engine is running in idle and the throttle lever is switched to full thrust instantaneously at t = 0 ...
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1answer
189 views

Is a cambered or symmetrical propeller airfoil more efficient?

Is an cambered propeller more efficient than a symmetrical propeller for a low speed airplane?
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3answers
289 views

Will the steep beta descent mode become illegal for new aircraft?

The PC6 is a popular skydiver carrier due to its ability to use steep nose down beta descent to get back to the ground quickly, even beating free falling skydivers. (YouTube) FAA AC25.1155x (I only ...
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1answer
85 views

Consumer Drones with multi-blade (more than 2) propellers

Maybe unusual question but it's related to Aviation world, even if is more directly related to Drones one. Why almost all consumer drones like DJI's and Yuneec's ones (but it's true also for other ...
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How to properly estimate induced flow

Good day. I am currently in a group that is projecting a rotor that when launched must enter in autorotation. The estimated velocity of descent is $V_z=1.29$ $m/s$ which is approximately the same ...
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At what rpm does the tip of a 54" propeller start to incur mach losses?

At what rpm does the tip of a 54 inches propeller start to incur mach losses? The max rpm of my engine is 3600.