Questions tagged [airfoils]

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Is standard airfoil theory suitable to VAWT blades?

Let me preface this by saying that I did my research and have r̶e̶a̶d̶ skimmed a lot of papers on new blade profiles for vertical-axis wind turbines (VAWTs). What I have yet to read about is a blade ...
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3 answers
108 views

Fin airfoil holder design and technical drawings not understood

I am trying to draw a fin for my final year project, but I could not fully understand the technical drawing explanations that I marked with red markings. especially R1.281 DEFINES TANGENCY OF R1.312 ...
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20 views

Lift/Drag on sheet metal airfoils

I watched a youtube video about a propeller-driven bicycle and it brought me back to my university days of designing propellers. In college, we used NACA airfoils and used the publically available ...
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1 vote
1 answer
162 views

Why does centre of pressure move forward with increasing angle of attack in this airfoil?

As a high school student, I am trying to learn more about airfoils and the theory behind it. I started off with analyzing the NACA0012 airfoil on Autodesk CFD. I modified the lower surface as shown in ...
0 votes
1 answer
58 views

Positioning and size for a Joukowsky Airfoil

Joukowsky transformations are absolutely eluding me because I can't find numerical examples (I have a learning disability and formulas have always made absolutely no sense to me). I'm trying to get an ...
1 vote
0 answers
137 views

what is the difference between jblade, qblade, and xflr5 softwares?

I am working on a propeller design, and I've came through Jblade which helped me in the airfoil design, yet as I can remember, xflr5 can also do this... doing some internet search, i found that Jblade ...
0 votes
1 answer
196 views

What foil profile(s) does the MIT Decavitator (or similar vehicle) use?

I'm looking for some kind of "standard" hydrofoil profile suited for a water vehicle comparable to the MIT Decavitator (similar weight/speed/power/etc.), so I can use it as a base to get ...
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1 vote
0 answers
62 views

How to modify Airfoil thickness

I'm writing a fusion360 adding to model windmill blades. My first goal is to model the NREL Phase IV in which the airfoils (S809) definitions come with thickness and also span station (wich I¿dont ...
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1 vote
1 answer
97 views

Laminar flow hood/air straightener

I was looking at laminar flow filters to aid in my mycology work I'm doing. Most filters use an aluminum extrusion with fins. I figured the options out there are pretty expensive for what you get and ...
1 vote
1 answer
2k views

Estimating fan CFM from RPM, HP, and diameter

I am trying to determine the approximate CFM of several axial flow fans being used in agricultural storage in the developing world. The only information the storers have is the power, RPM, and ...
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5 votes
1 answer
117 views

Why don't propeller designers use multiple profiles?

I'm designing a ducted fan, and I'm deciding on the airfoil profile. NACA 16-series profiles are well-suited to M > .5 or .6, but they're not particularly efficient at lower Mach numbers. On the other ...
2 votes
0 answers
37 views

Generating NACA airfoils with three digit maximal thickness numbers

I have two wind turbine blades, one that that consists of NACA 44xx airfoils and the other NACA 63-2xx airfoils. Some sections of these blades have airfoils whose maximal thickness are specified by ...
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1 vote
1 answer
53 views

Can adding stationary bades after an axial ducted fan increase efficiency?

When searching for this online I did not seem to be able to find any examples of this, which might imply that this idea does not work (or I did not use the right search terms). I have seen the use of ...
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0 votes
1 answer
31 views

When were airfoil cross-sections first used in turbine blades?

When were airfoil cross-sections first used in turbine blades? When did this become standard practice? Did people understand the connection to aircraft, or did heavier-than-air aircraft exist at all ...
1 vote
0 answers
41 views

Determination of a Joukowski airfoil chord (demonstration)

I'm currently studying Aerodynamics, and one thing that I noticed is that the maximum and minimum $x$ coordinate of the airfoils (which are necessary to compute the chord) on the transformed plane (...
2 votes
2 answers
4k views

How to scale airfoil coordinates to achieve the required size?

I'm using airfoil data that is generated by a program. The generated airfoil has a chord length of 1 unit. I want to know how to scale up this airfoil to required chord length. My airfoil series ...
5 votes
2 answers
2k views

How to generate NACA 5 digit airfoil coordinates?

I want to generate NACA 63824 airfoil coordinates to use them in my bachelor thesis. I tried airfoil tools and java foil. But I can't generate 638xx series. Can you recommend me a program or a code ...
1 vote
1 answer
1k views

Wingspan formula for an Ornithopter

How do i figure out what the wing area/sqft needs to be for a functioning wing-flapping ornithopter? Lets say for example there is 500# of force moving the wings up and down, and the wings and ...
2 votes
1 answer
459 views

Hydrofoil for skeg-hung rudder with forward centre-of-effort

I am trying to see how much I can reduce the torque on a rudder post by changing the foil shape. I think I need a rudder with a centre-of-effort further ahead than average but I don't know what rudder ...
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3 votes
1 answer
154 views

What does high coefficient of moment mean for an aircraft?

After designing an aircraft idea I had in XFLR5, I noticed that it had a really high coefficient of moment (Cm) compared to other wings of similar size. What does this mean? I played around with my ...