Questions tagged [blade]

A blade is a thin section of material designed to push or be pushed by a flow. This can be a turbine blade which makes up the compressor or turbine section of a gas turbine, or the blades of a propeller or rotor.

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31
votes
4answers
10k views

Why are the fan blades mounted loosely?

In this question it is mentioned that the fan, compressor and turbine blades are mounted loosely in the disc. This is well demonstrated by this video posted by RedGrittyBrick. What is the reason for ...
26
votes
3answers
5k views

Which manufacturer produced this fan blade?

I acquired a fan blade a few years back, but have not had any luck finding out who manufactured it or what engine/aircraft it may have come from. The only data I can find on the blade is as follows: ...
21
votes
1answer
4k views

Can you identify this jet turbine stage?

I was just wondering if anyone could give me any info about this turbine rotating stage I picked up at a yard sale today. The stage measures 8-1/2" to the outside of the blades. The only markings I ...
19
votes
2answers
22k views

Why are aircraft turbine blades made of nickel alloys?

Why are aircraft turbine blades made of nickel alloys? What is the advantage of using them? Why did they replace steel alloys for turbine blades? How to overcome failure cases of turbine blades?
17
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6answers
6k views

In helicopters, why not have electric motors controlling blade pitch?

From my related question comes this idea of electrically controlled blade pitch in helicopters. Control linkages in helicopter rotors seem to be pretty complex. This surely incurs a lot of friction, ...
13
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2answers
2k views

What engine are these fan blades from?

I bought these from a metal scrapper and paid about $30.00 total figuring they're worth more than that in cool factor. Problem is they aren't nearly as cool if I can't figure out what engine (and ...
11
votes
2answers
2k views

How are helicopter rotor blades balanced?

Reading this answer, I realized that the balance of a rotor is critical. When one blade is changed, the whole balance of the rotor may be affected. Moreover, I doubt 2 blades are exactly the same. For ...
9
votes
1answer
835 views

How does increasing the RPM result in a higher AOA for the blades?

I know that an increase in velocity (TAS) reduces the AOA and that makes sense. But how just simply increasing the blade rotation (RPM) results in higher AOA?
8
votes
1answer
407 views

Are engine casings expected to contain turbofan blade fragments?

On Southwest 1380, initial indications are that a fragment of the engine blade pierced the engine casing, which then hit the airplane window (or perhaps a part of the casing did). According to the BBC,...
7
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3answers
9k views

Why don't helicopters prefer shorter rotors with more blades? [duplicate]

My understanding of helicopters is that, despite theoretically increasing efficiency, longer blades are worse in practice than short ones in every respect (except, perhaps, cost): Longer blades are ...
6
votes
2answers
312 views

What would happen if the blades of a variable pitch prop did not all have the same pitch?

What would happen if one or more of the blades (but not all) on a variable pitch prop would not tilt at the same angle as the other ones? Could this situation happen or is the technology so advanced ...
5
votes
3answers
2k views

How does the relative wind on a propeller, strike the blade from behind (the non camber side)?

This may be a stupid or simple question, although any help is appreciated! :) If possible, please answer without mathematical terminology. So I understand the concept of the blade increasing air ...
5
votes
1answer
2k views

What is the fan tip speed at maximum thrust?

What is the fan tip speed at maximum thrust? Is it any different for a Rolls-Royce Trent 900 (powers the Airbus A380) and Pratt & Whitney PW6000 (powers the Airbus A318)? Are they efficient at ...
5
votes
1answer
1k views

What could cause a low-pressure compressor first stage blade of a turbofan engine to bend forward?

What could cause a low-pressure compressor first stage blade of a low-bypass turbofan engine to bend forward? I also noticed rotor path rubbing in the 9 to 12 o'clock portion (while usually this can ...
5
votes
1answer
392 views

Are there any helicopter blades that fold in the middle?

Let's assume that, for some arbitrary reason, helicopter blades are too long for transport or storage. Folding them at the rotor hub, as is done with conventional folding helicopter blades, would ...
4
votes
1answer
900 views

Do fan blades use bell shaped lift distribution curves?

Seeing the organic curvature of some newer fans in turbofan engines, I'm curious if they use bell shaped lift distribution curves in their design, or something else all together.
4
votes
3answers
181 views

How to estimate blade interference in a propeller or fan?

The ideal propeller has one blade. For obvious reasons, that would be impractical. However, adding more blades causes each blade to operate in each others slipstream/downwash. How to quantitatively ...
4
votes
1answer
1k views

What is the longevity and replacement schedule for turbine engine blades?

I'm trying to understand how frequently hot section turbine engine blades are changed out. Is this a calculation based on flight hours, material, engine size or maybe something else? Apologies if ...
4
votes
2answers
2k views

Is it possible to get a list of Cl/Cd values for various NACA Airfoils?

There are a lot of links which give the shape of the airfoil for any given set of camber thickness, position and max. thickness values, but I would like to know if it is possible to get the Lift vs. ...
4
votes
1answer
175 views

How does a Delta-3 hinge on a helicopter tail rotor work?

I am trying to understand how adding offset hinges would provide a self-feathering force. Does anyone have more information on Delta hinges on helicopters? I am a bit confused with the information I ...
4
votes
1answer
262 views

How are turbine blades overhauled?

How are turbine blades overhauled? What techniques are commonly used and how does it affect the integrity of the blade?
4
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0answers
127 views

How do active blades work on helicopters?

Can someone throw some light on 'active blades' as used in helicopters? I'm mostly interested in the use of piezoelectric material and actuators. How are the actuators able to sense the change of ...
4
votes
1answer
133 views

How heavy are turbofan and turboprop propeller blades?

How heavy are the blades from Turbofan (CFM56-5B, RRTrent800, PW4062A) and Turboprop (PW127M) engines? Is there a general appromixation like $$ m_\mathrm{Fan} = 0.1 \times m_\mathrm{Turbine} $$ ...
3
votes
3answers
12k views

What is the difference between axial compressor blades and centrifugal compressor blades?

Is there a particular difference? The way they're overhauled is the same ? (I mean do we use the same overhauling methods ?)
3
votes
2answers
486 views

What is the correct equation for rotor solidity?

I'm working in a project that uses"blade solidity ratio", or "rotor solidity", the problem is, there are several articles which defines the equation in a different way changing in the section of the ...
3
votes
1answer
249 views

Is the rotor described in this Kickstarter new?

A NewAtlas story linked to a Kickstarter for a the "Whisper Drone" that shows a CAD model of a rotor that the Kickstartee-aspirant has apparently 3D-printed and flown (four of) on a quadcopter. I ...
3
votes
2answers
7k views

Why do jet engine fan blades have a twisted shape?

is this a good answer. the blades rotate, the tip moves faster than the hub. So to make the blades efficient, the blades are usually twisted. The angle of attack of the blades at the tip is lower than ...
3
votes
1answer
96 views

How to calculate the number of blades?

Inspired by building a new drone, I got lost in curiosity. What if I have a fixed length of rotor blades and a target amount of lift I want to, well, lift. How do you calculate the number of blades? ...
3
votes
0answers
66 views

Do contra-rotating props have worse tip vortices than single props?

As I understand it, blades from a propeller have their own tip vortices, because the blades produce lift via the same aerodynamic principles as wings. So they must have tip vortexes too. So with ...
3
votes
0answers
300 views

Is there an engine database that would include information on number of HPT blades per engine?

I am attempting to compile information on the number of high-pressure turbine blades across a wide range of turbine engines. Currently, I have only been able to find this information through brut ...
2
votes
1answer
257 views

How much do the blades on the V22 or AW609 weigh?

It seems that the blades on the V22 or AW609 would have to be heavier than conventional helicopter rotor blades since they have to be substantially stiffer when in fixed-wing mode. Normal helicopter ...
2
votes
2answers
243 views

Does the compressor stationary vane have stagger angle?

Does the compressor stationary vane have stagger angle? ( stagger angle is the angle between chord of the blade or vane with engine's longitudinal axis )
2
votes
1answer
198 views

Could a shrouded fan blade with long chord length be efficient?

I am wondering if it would work to have a fan with two or three blades which have short-ish span and very long chord length, like half a rotation for each blade. Would a shroud (that is molded on the ...
2
votes
1answer
151 views

How often are turbine blades in jet engines replaced?

How often are the turbines in the hot section of the jet engines replaced due to deteriorated TBC? or just how often are they replaced? lets say for CFM56-7
1
vote
1answer
2k views

How can I calculate the thrust of a fan given the diameter of the blade?

How do I calculate the thrust of a multicopter fan blade from its diameter? I am searching for a multicopter blade that can provide a thrust of 15 - 20N. Being someone who doesn't have any ...
1
vote
2answers
2k views

How to design the blade twist angle in propeller design?

I am designing a scale propeller for small UAVs and I have computed blade twist distribution for the blade airfoil sections. While I was modelling the propeller I have set the angles to twist about ...
1
vote
1answer
131 views

Quadcopter: would putting 3 blades on the same level and the other blade below the first three work?

Most quadcopters have their propeller blades all on the same level, or in some cases, a pair of blades placed a little above the other pair. However, I was wondering if three propellers of a ...
1
vote
0answers
24 views

How to calculate the moment/torque at the center axis of a blade?

How do I calculate the moment/torque at the center axis (same plane with lift and drag force) of a blade with NACA airfoil standard when it is placed inside a wind tunnel or exposed to airflow?
1
vote
0answers
60 views

How accurate is blade element theory?

for a ducted fan/propeller, how accurate is BET? does it overpredict the thrust and underpredictes the torque? in other words, the power absorbed. if so, by what percentage approximately?10%?15%?
1
vote
0answers
222 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 ...
1
vote
0answers
280 views

What causes these losses in this propeller simulation?

While running a CFD simulation comparison of 2 vs 3 blade propeller versions (48" diameter, 23" pitch, 3570RPM), I've come up with: 2-blade: 347N of static thrust @ 110Nm Torque 3-blade: 220N of ...
0
votes
1answer
1k views

Is low pressure compressor air used to cool turbine blades?

This photo shows LP cooling air is being used to cool turbine blades. the question is, is it possible to use LP air to cool the turbine blades? would you please guys explain why do they use LP air ...
0
votes
1answer
208 views

How are this helicopter's blades perfectly timed with the camera shutter? [closed]

This is a video of the Mi-24 helicopter. The rotor blades appear not to be moving. Did the pilot and photographer sync the camera and helicopter to make this video and how? I do not know the true ...
0
votes
1answer
221 views

Which helicopter can auto rotate the farthest? [closed]

Could the rotors be modified to perform better at auto rotating and maybe less at powered performance?
0
votes
1answer
121 views

What rotors would be best for atmospheric reentry?

What rotor blade set up would be the best for entering Earth atmosphere or to shed speed before landing in place of a parachute? I understand that the longer blades are more efficient, but are not as ...
0
votes
0answers
31 views

Will two blades or three blades last longer on a hobby drone? [duplicate]

Will it be better to run a lighter 2 blade prop vs a heavier 3 blade prop for longevity and battery life? they are the same length. I am curious if the extra weight of the third blade will inhibit the ...
-1
votes
1answer
403 views

What is the market size of high-pressure turbine blades for commercial aircraft? [closed]

I need to calculate the market size for high pressure turbine blades which are used in commercial aircraft. I am working on a business school project on this topic. Any information which can be used ...
-7
votes
1answer
2k views

How do the propeller blades accelerate air resulting in thrust to push an aircraft forward? [duplicate]

I do know that the blades on a propeller generate lift to provide a force pushing back on the air based on newton's law the 2nd. What I am having trouble understanding is how the blades generate ...