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Questions tagged [airfoils]

23 questions
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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 hand, older profiles, like Clark YM, work quite…
user1493362
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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 that generates these airfoil coordinates?
papabiceps
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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 center of gravity and the coefficient went down,…
Tarik Agcayazi
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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... I found that Jblade is based on qblade and xflr5/xfoil... so does this mean the jblade is more…
Ibrahim Jaafar
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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 three digits, such as .247c (where 'c' is the chord…
Eric Q.
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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 number 638xx. NACA five digit series.
papabiceps
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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 passenger combined weighs 250#. What is the minimum…
E. Pence
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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 series to use. Balancing the rudder (in a spade…
avs
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Could a boat 'sail' in a river using the difference in water velocity between shallow and deep water?

Sailboats operate in an environment with two fluids moving along different vectors: the air, typically moving as wind, and the water, typically almost stationary. Two foils, the sail and the keel, use the relative movement of the two fluids to…
Sam
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Recreating a blade in CAD using a data file from Matlab

I'm running a numerical data model of a wind turbine. I know the blade in question is an S814, as described in the NREL documentation here. I have the necessary blade size data in a MATLAB file shown below: So far, I know that Cd and Cl are the…
mrmurmanks
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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 profile that is optimized with the recognition…
fho
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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 the image below (the modified airfoil simulation…
RoseDuda
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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 know what is): Right now, I'm able to calculate the…
efirvida
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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 figured I could just 3d print my own…
Robert Dawson
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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 diameter of their fans. I would like to estimate the CFM…
Anthony
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