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Questions tagged [blade]

Use for a gas turbine's, propeller's, or rotorcraft's blades

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32 votes
4 answers
13k 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 ...
TomMcW's user avatar
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26 votes
3 answers
6k 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: ...
Pete Jovanovic's user avatar
23 votes
1 answer
7k 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 ...
Jason Freier's user avatar
23 votes
1 answer
3k views

How much weight does a blisk save?

A Blisk is a bladed-disk, all one monocoque component. So the blades do not have to be inserted and secured, and they are not removable. No nuts and bolts either. The downside is that any serious ...
DrZ214's user avatar
  • 17.8k
19 votes
2 answers
24k 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?
user8325's user avatar
  • 191
18 votes
7 answers
9k 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, ...
DrZ214's user avatar
  • 17.8k
18 votes
2 answers
7k views

Why does each fan blade have a different mass and frequency?

From a documentary (at 16:39) on building a Rolls-Royce jet engine: ... no two finished blades are exactly alike, and with twenty in each fan, it will only spin smoothly if the blades are perfectly ...
Auberron's user avatar
  • 1,567
14 votes
2 answers
3k 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 ...
Garrett Schneider's user avatar
14 votes
1 answer
7k views

What are those ball-shaped things on some helicopter blades?

I saw these things swinging in a video of a rotor from the blade point of view. I don't know what are they for but I am quite curious. And why some helicopters have it and some don't? Source: alamy ...
Thefermar337's user avatar
14 votes
2 answers
735 views

What are these painted lines on the fan blades of the Rolls-Royce Pearl 15?

I'm not sure that they are painted but it looks like they are. What are they for? More images:
Roh's user avatar
  • 3,329
13 votes
2 answers
4k 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 ...
Manu H's user avatar
  • 16.5k
11 votes
3 answers
4k views

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 ...
SRD's user avatar
  • 383
10 votes
1 answer
1k views

What is the function of the aft stator in CFM's open rotor engine design?

CFM revealed their design for a open rotor propfan engine with two stages of blades - one active set of blades rotating in the forward and an static sets of blades on the aft. According to The ...
karthikeyan's user avatar
9 votes
1 answer
1k 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?
Mike no smith 's user avatar
8 votes
2 answers
435 views

What are the design principles that result in thin, long-span, narrow chord main rotor blades?

Regardless of the overall design configuration of a helicopter, it appears that helicopters have main rotor blades that all fall into the class of ultrahigh aspect-ratio wing design: that is, you ...
niels nielsen's user avatar
8 votes
1 answer
459 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,...
adam.baker's user avatar
7 votes
3 answers
555 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 ...
Fabrizio Mazzoni's user avatar
7 votes
3 answers
12k 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 ...
feetwet's user avatar
  • 2,284
7 votes
5 answers
15k views

Why do jet engine fan blades have a twisted shape?

I'm thinking: as 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 at ...
D. Frederico's user avatar
6 votes
1 answer
4k 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 ...
securitydude5's user avatar
6 votes
1 answer
1k 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 ...
Eth's user avatar
  • 763
6 votes
1 answer
649 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 $$ m_\mathrm{Fan} = 0.1 \times m_\mathrm{Turbine} $$ ...
M P's user avatar
  • 61
6 votes
1 answer
181 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 ...
DrZ214's user avatar
  • 17.8k
5 votes
3 answers
3k views

Helicopter mast bumping in low g condition

The helicopter shown in the concrete pouring video seems to taking off from a hill and descending down in a way which can be classified as low G with low rotor loading. Although, the helicopter is ...
user19440's user avatar
  • 1,075
5 votes
3 answers
7k 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 ...
Gerry's user avatar
  • 848
5 votes
2 answers
614 views

Why does the helicopter Robinson R22's rotor blade have flat part as in the picture? What is it for?

Picture source: Picture source: This is Robinson Helicopter R22's rotor's blade. What is this flat part for as indicated by the red line? What is the aerodynamic benefit of putting it? There are many ...
AirCraft Lover's user avatar
5 votes
3 answers
4k 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 ...
ApolloMission4's user avatar
5 votes
3 answers
27k 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 ?)
Vi Z's user avatar
  • 91
5 votes
1 answer
2k 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 ...
Anso Mamachan's user avatar
4 votes
3 answers
1k views

Why do some jet engines have fewer fan blades than others?

I have found out upon researching jet engine fan blades that they can vary from 16 to 34. Why do they vary, I mean, does decreasing or increasing the number of fan blades have any performance impact? ...
Aviation Enthusiast's user avatar
4 votes
1 answer
1k 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.
Jim's user avatar
  • 737
4 votes
1 answer
1k views

Why are jet engine fan blades painted?

I came across this extremely interesting article with details on a 2018 United Airlines Boeing 777 engine failure, which is also related to the more widely-publicized failure a few days ago: http://...
rob74's user avatar
  • 186
4 votes
2 answers
671 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 ...
FZ123's user avatar
  • 75
4 votes
3 answers
332 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 ...
toshi ba's user avatar
  • 411
4 votes
1 answer
2k 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 ...
Scott's user avatar
  • 73
4 votes
2 answers
4k 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. ...
Manish's user avatar
  • 569
4 votes
1 answer
965 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? ...
Arie's user avatar
  • 117
4 votes
1 answer
441 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?
Vi Z's user avatar
  • 91
4 votes
0 answers
168 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 ...
M Kartik Reddy's user avatar
3 votes
3 answers
854 views

What causes ram air turbines with more blades to spin slower than turbines with two blades? [closed]

Lets say aircraft has two ram air turbines that work as generators to produce electricity on each wing. One has two blades and one has 8 blades, both with the same diameter. What is the aerodynamic ...
22flower's user avatar
  • 1,958
3 votes
1 answer
211 views

Why can the rear rotors of helicopters move freely in this direction?

As you can see in the video in the imgur link below i recorded a video of the Alouette 2 rear tail rotor and as you can see it moves freely in that direction. Why does it freely move in that ...
Timothy Scherer's user avatar
3 votes
3 answers
4k 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 ...
Resou's user avatar
  • 31
3 votes
2 answers
344 views

Is blade flapping "fully automatic"?

I have a rather simple question just to "double check" if I understood blade flapping right. So, I understand that a helicopter, in forward flight faces an asymmetric lift. Blade flapping is ...
Clex's user avatar
  • 173
3 votes
2 answers
476 views

Why phase lag on helicopter blade is sometimes 90°, and sometimes less?

On semi rigid rotor head, phase lag is 90°, and also the advance angle between pitch link and coresponding blade. But of fully articulated rotor the phase lag is less then 90°, and also the advance ...
cirica's user avatar
  • 161
3 votes
1 answer
521 views

From which jet engine is this blade?

Some years ago I bought a compressor blade on ebay but I don't know which jet engine it's from. It's quite light. I tried to determine the density by the help of my kitchen equipment and it's most ...
Rednose's user avatar
  • 83
3 votes
1 answer
268 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 ...
Erin Anne's user avatar
  • 837
3 votes
0 answers
350 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 ...
Scott's user avatar
  • 73
2 votes
1 answer
710 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 ...
Christophe Pochari's user avatar
2 votes
2 answers
339 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 )
Mehdi shelby's user avatar
2 votes
3 answers
144 views

What other materials apart from conventional nickel and steel superalloys can be used as a first stage turbine blade material?

Steel and nickel chromium alloys have been prominent and most used as turbine blade material although there are other materials such as tantalum carbides, tungsten and many more which I have no ...
Walter White's user avatar