# Tag Info

6

There are propellers with different aerofoil sections. For example, the propeller attached to the Rolls Royce engine kept in my graduate college had symmetric aerofoil sections roughly about 25 % and smoothly varying to bottom flat airfoil sections at the rest. The aerofoil profile selections are based on the performance requirement, structural rigidity, ...

3

This is basically a list of resources gleaned from having followed the HPV boat development for the past twenty years. Here's a good sketch of how to go about exploring the hydrofoil design space. You need human factors input very early on, a good sense of drive train layout and expected efficiency, and a realization that one pedaling person has a massive ...

3

Good description in the link, but curved surfaces were in use as sails around 800 years ago and Bernoulli came up with his formula , Ludwig Prandtl was testing sections in 1017 in his large wind tunnel, the first naca section was tested in 1935 .... http://www.flyingmag.com/technicalities/technicalities-short-history-airfoils And this link to Sir Frank ...

3

This is a simple math question. Multiply your x and y coordinates by the scaling factor you want. Say your chord length is 100mm. To make it 150mm, multiply all your values by 1.5. If you have a picture of an airfoil, just scale the image by 150%.

3

As a Naval Architect, this is a question that I am often asked. The centre of effort is very close to the geometric centre of the spade as you know. Is there a fixed skeg or keel immediately in front of the rudder? That affects the hydrodynamics significantly because the hydrofoil would then have an effective length that is the skeg width (aligned with ...

2

The coefficient of moment is related to how much the wing makes the plane want to pitch up. This torque is taken about the center of gravity and thus moving the center of gravity changes the moment. If you measure the torque about an arbitrary point, the value will usually depend on the angle of attack. However, there are some points where it remains ...

2

MountainClimberi is correct. Multiplying both x and y coordinates by the same factor will scale your airfoil correctly. Using a different factor for each will result in a different aspect ratio and a different(stretched) version of that airfoil that will not match its published properties. Also remember that after scaling the data, your reference location ...

2

Wing loading: The graph below provides areas for living and man made flying machines - and this can be seen to be a quite good log-log fit of mass and wing loading. See his text for comment on the departure of Humming birds from the continuum mapped by most other birds. The graph suggests wing loadings of 30 to 80 kg/m2 as mass rises from 100 to 300 kg. ...

2

Just doing a quick search, this NASA paper (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810020599.pdf) indicates that no particular geometry has significant advantages for producing flow uniformity. I would stick to a well-tested geometry that is the simplest to produce with a 3D printer. Also, keep in mind the purpose of using honeycomb is to ...

1

Theories are developed to represent something happening in reality, in a form of mathematical model. Theory is not the benchmark, reality is. You cannot use a theory to prove something which is happening in reality, but can only develop a theory so that this reality can be represented correctly. Sometimes, using a specific theory to gain reasoning for a ...

1

Joukowski airfoils use a transformation to turn a circle into an airfoil, essentially. This is why the mathematics are so complicated. There are a lot of resources out there on making Joukowski plotters. Here is an automatic one you can use to check your work (http://airfoiltools.com/plotter/index?airfoil=joukowsk-il). Basically, you define a range of points ...

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Yes, it depends on if it is cost effective; for a consumer window fan = No. For a consumer vacuum cleaner =Yes. Of the jet engines I have seen , every stage of blades ( rotating) has a stage of vanes ( stationary).... Except the first stage/fan.

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If you are a MATLAB or Oculus user, there is the NACA 5 digit Airfoil Generator program you can use. It works very well, considering it calculates the plot, as well as other main features of the airfoil, given the airfoil type. Now, I am unaware of a program that gives plots based on the formula, but if you ever DO find out, please do not hesitate to post ...

1

NASA Technical Memorandum 4741 describes the calculations for Series 6 and 6A foils on page 8. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970008124.pdf

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