Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [propeller]

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

4
votes
0answers
260 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 ...
1
vote
0answers
149 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 (...
1
vote
0answers
106 views

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
3
votes
2answers
156 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,...
0
votes
2answers
126 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 ...
0
votes
0answers
82 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 ...
5
votes
2answers
937 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, ...
3
votes
2answers
1k 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 ...
3
votes
1answer
751 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 ...
3
votes
1answer
221 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 ...
4
votes
3answers
771 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 ...
2
votes
1answer
279 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 ...
6
votes
3answers
431 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?
5
votes
1answer
431 views
17
votes
4answers
3k views

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 ...
1
vote
1answer
112 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 ...
2
votes
1answer
229 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 ...
3
votes
1answer
206 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 ...
1
vote
0answers
154 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 ...
2
votes
2answers
674 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?
3
votes
2answers
942 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 ...
0
votes
2answers
212 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 ...
0
votes
1answer
282 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?
7
votes
3answers
355 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 ...
1
vote
1answer
107 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 ...
0
votes
0answers
26 views

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 ...
7
votes
3answers
3k views

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.
2
votes
2answers
295 views

Is a propeller with two long blades more efficient than one with three shorter blades? [duplicate]

Is a longer, two-bladed propeller more efficient than a three-bladed propeller with a smaller diameter?
2
votes
2answers
206 views

Which engine manual must a pilot legally use?

Many aircraft have engine/prop performance information provided by the manufacture such as Bonanza, Cessna, Mooney, etc AND the engine manufacture. The performance or recommended settings may vary ...
7
votes
2answers
500 views

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 ...
0
votes
1answer
284 views

Does the direction of rotation of the propeller affect the direction of the thrust generated?

Does changing the direction of rotation of the propeller from clockwise to anti-clockwise change the direction of thrust it generates?
1
vote
1answer
257 views

In what way are the airfoils used for a propeller different from the ones used in turbofan engine?

Airfoils are used in the blades of a propeller as well as the blades of the fan, axial compressor and turbine in a turbofan engine. Thus, the airfoils used in above two applications have different ...
3
votes
0answers
331 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 ...
0
votes
0answers
178 views

What is the relationship between speed, torque and pitch in a helicopter?

Can someone clarify the relationship between aircraft speed, torque, prop length and pitch and how this applies to a helicopter. In addition I want to know if the amount of lift a helicopter ...
11
votes
1answer
496 views

Why do helicopter rotors have constant section and angle of attack?

As I understand it helicopter rotor blades keep a constant aerofoil section along their length, and are not twisted. Other rotating aerodynamic devices such as propellors, turbofan fans and wind ...
2
votes
2answers
863 views

How do propeller planes suddenly make noise?

I was wondering: how can a propeller plane, single engine or otherwise, be flying along relatively silently and then start making noise, often very loud--and then turn it off just as quickly? Are they ...
9
votes
1answer
322 views

Is there a fixed-wing aircraft that uses a scissor propeller configuration?

(Source: primeportal.net) Has there ever been a fixed-wing aircraft whose propeller is in a scissor configuration? Like the Apache's tail-rotor seen here: What are the benefits of a non-orthogonal (...
1
vote
0answers
70 views

Would propellers be more efficient if they were mounted at the rear of the aircraft? [duplicate]

The propellers of a front-mounted propeller plane push air back directly on a collision course with the aircraft's body. That results in zero thrust or negative thrust from at least some sections of ...
5
votes
2answers
443 views

How much safer does painting prop tips make a plane?

While re-reading one of my earlier questions, the answers left me wondering how much good painted tips on props actually does. I did some searching for statistics but didn't come up with much. Are ...
3
votes
0answers
167 views

What typical improvements in lift/drag are gained using dimple & zig-zag strips? [duplicate]

A golf ball goes twice as far using a dimpled surface. Many European aircraft (especially gliders) use dimple strips or zig-zag tape on propellers, wings, struts etc. Very few US aircraft use these ...
0
votes
0answers
27 views

What are the design trade-offs between a pusher and a puller propeller? [duplicate]

Wich is the difference in having the propeller forward or back in an airplane. I would like to know the technical differences like in a Piaggio 180 or in a normal Cessna.
5
votes
2answers
196 views

Does rolling affect the thrust of a propeller?

If a plane with a propeller, e.g., a Spitfire, does a constant barrel roll in the same direction as the propeller, will the plane travel faster as impractical?
15
votes
2answers
1k views

Why are there different number of propeller blades on the inboard and outboard engines?

The Junkers G 38 has four propeller blades on the inboard but only two on the outboard engines. What's the reason for this special arrangement and is there any benefit?
2
votes
1answer
749 views

Is there a mathematical formula to find the most efficient propeller? [duplicate]

Is there a mathematical formula to find the most efficient propeller? Is a five-blade better than a four-blade? Does software exist to aid in the calculations there?
2
votes
1answer
501 views

Is there a pressure rise and velocity change across a turbofan fan and stator?

I've been looking at the pressure / velocity / temperature diagrams across jet engines. These have really helped me to understand the different roles that the compressor/turbine stator and rotors play,...
6
votes
5answers
2k views

Guidelines for using a constant speed/adjustable pitch propeller

I have been trained in a single engine fixed pitch prop ( C152). I'm trying to move to Piper Arrow II which has an adjustable pitch propeller. I understand how constant speed propellers work. I'm ...
3
votes
1answer
626 views

Would it be possible to build a “rocket” using a series of ducted fans?

I'm wondering if it would be possible to build ducted fan "rocket". My idea is to construct the duct from 18650 batteries, and to have a series of contra rotating fans along its length. I can 3d ...
0
votes
1answer
2k views

How to calculate Blade angle?

If we know the helix angle is 3angle, forward speed is 150mph, and rotational speed of propeller is 1500rpm How can i calculate the blade angle of propeller ?
2
votes
2answers
3k views

How do I compute thrust of a rotor disk and the necessary power to drive it??

as it seems, this question has been asked a few times here so please forgive me for asking again. If I have 50 BHP shaft power available at 5000 RPM and 106 N.m torque, then can I convert it to 200 ...
0
votes
2answers
487 views

How far should the two propellers on a twin engine plane be apart?

I was wondering if there are any specific ways to calculate the appropriate distance between two propellers for a twin engine twin fuselage planes like a Twin Mustang plane?