Does this srcipt can be used also for boats' propeller blades ?

Hi,

No, sorry. However, if anyone knows enough about marine propellers, it should be a pretty easy code update. I don't know anything about them, but I think you would need to use a hydrofoil model rather than an airfoil model, account for cavitation, chord distribution options appropriate for marine propellers, and use water properties rather than an atmospheric model. Other than that, PROP_DESIGN probably would work for marine propellers. But you would need to consult with an expert or be an expert in that area to know for sure.

I have a version of PROP_DESIGN, that I haven't released, that you can enter any fluid properties. So that part is already done. I looked into hydrofoil properties at one time, but not having any experience with that, I didn't pursue it too much. If that is something you know a lot about, the two of us should be able to get the update done.

I only have expertise with aircraft propellers. Which is why I haven't adapted PROP_DESIGN for helicopters either. I could adapt it to wind turbines but have no desire to. Just not into wind turbines. I have been interested in propellers since college. Studied them for years and then took jobs in that industry to learn more. So a lot of man hours went into PROP_DESIGN. I am not the kind of person to just code something I don't know anything about.

PROP_DESIGN is open source though. I released it as public domain software. So you could do anything you like with it. No need for my permission or anything. My hope is people will develop it more and make it even better. I wanted to give students something better than I had to go through to learn about propellers. I accomplished that. However, as far as software goes, PROP_DESIGN could use the love/development attention of many types of engineers (marine, aerospace, structural, software).

Anthony

Custom distance script can be used to measure the Y and Z coordinates of a point, (distance to axi.)
First increase the number of digits, as previously posted on the forum.

Here is an update to the MoI script version, PropDesignGeoOptionA.
It uses Option A, pre-calculated "tangent" points, which is probably better than trying
to find the points by arc, or circle interception, as there could be zero or two intersection points.

Most of the coding for the previous version was re-used, with slight change, except for the four arc intercept coding.

The mirrored tangent points were easy to get, just negate the y values. The arcs are on both sides, no need to mirror them.

I think it would be easy to script mirror the airfoil spline, with the mirror factory...

On a side note, still trying to figure out how to extract the x, y, and z values, from a given point.
Either vector math, or the "get" method in point?

thanks brian,

i'll check it out. i was just about to post a hack i did of your script to give you and idea of what i was thinking. but let me see what you have here. i noticed one thing with the previous scripts. they don't use the hub end point input. what that input is for is to make a circle at the point specified. the circle would be in the top view and use the point on the 1/4 chord line. the first point being counted as 1. so it should be relatively easy. since that input would just be making a circle. i was able to use trial and error and beat the script into submission. however, i don't know enough to actually add something to it. i was just editing what existed.

anthony

hi brian,

i like what you got. its a little better than what i did. the only thing i changed form what you have now is removing the points from the le and te rails. the points are only needed on the 1/4 rail for reference. i also tried taking the curve off the 1/4 rail but that made it graphically hard to look at. so i ended up putting the curve back on the rail along with the points.

if you do go about mirroring the airfoil spline, would it be possible to join all four curves of the airfoil definition, so that it was one joined curve. if so, it would be reading to sweep, with no work.

great job.

anthony

Hi Anthony,

> noticed one thing with the previous scripts. they don't use the hub end point input. what that input is for is to make a circle at the point specified. the circle would be in the top view and use the point on the 1/4 chord line. the first point being counted as 1. so it should be...

Are you talking about HEP? All I see in the GEO script, is HEP = HEP + 1, but do not see where HEP is used anywhere in the GEO fortran code.???

Is the Airfoil curve near the center of the "fan," and offset from the centerpoint, by the Hub "radius"?

Please explain a bit, or elaborate. (Seems to me, the one time I imported to MoI, your fortran points, that there was an offset from y=0 axis???)

Hi Brian,

Yes the geo code does not use the hub end point. I think it was just left there because I copied that code from PROP_DESIGN. PROP_DESIGN uses the hub end point. But for the MoI script you can either take it out completely or if you want to implement it, it would be a circle at the specified point along the quarter chord line. 0,0,0 being point number 1. So if the user input 3. That would be two points away from 0,0,0 along the quarter chord line.

The fortran codes should place the airfoil in the right view of MoI with the quarter chord point being at 0,0,0. There should be no offset.

I just updated PROP_DESIGN, PROP_DESIGN_OPT, and PROP_DESIGN_GEO. After working withe MoI for awhile and your script. I took lessons learned to make it even easier to go from PROP_DESIGN to MoI. I will be posting an updated screencast soon. You won't believe how easy it is now.

This method may help you with scripting as well. Since everything is practically done for you. You could just read in the various files. The leading and trailing edge radius' can be created with the two point arc now. It should all be clear in the forthcoming screencast. Give me about an hour to get it recorded and uploaded.

PROP_DESIGN and PROP_DESIGN_OPT are on my website. Here is the latest version of PROP_DESIGN_GEO.

Anthony

Edit; Download the latest version, contained in a later post.

Here is a link to an updated screencast, showing how to import the PROP_DESIGN .XYZ data files into MoI for the purpose of creating an aircraft propeller blade model.

Anthony

Edit; the latest screencast link is in a later post

Hi Brian,

> On a side note, still trying to figure out how to extract the x, y,
> and z values, from a given point.
> Either vector math, or the "get" method in point?

There are a couple of different kinds of points - there's a "point object" which is one that can be added to the geometry database and will then show up on the screen and can be selected and assigned an object name and so forth, and then there's a plain data point as well that only contains x,y,z values and nothing else.

If you have a "point geometry database object" that you might have got as a result from a geometry factory or something like that, then that object has a "pt" property on it that will return a plain data point that has the x,y,z values in it.

So you would do something like this to get the data structure point from a point object:

var datapt = pt_object.pt;

Then for the data structure type point has x,y,z values that can be accessed like:

var x = datapt.x;
var y = datapt.y;
var z = datapt.z;

Hope this helps!

- Michael

Here is the NACA 4, 5, and 6 series airfoil generator from the PDAS site. I compiled it and created an input file for the NACA 65A009. This is an update to the code I posted previously from their site. It has about half as much error as the older version. However, it is still a substantial amount of error (max. of 2.28% for the new version compared to 5% for the old version). I wouldn't recommend using this code for the 6 series. I'm providing it here for anyone interested.

The updated code is a lot more convenient to use than the older version. It outputs to gnuplot rather than a postscript file. The output matches the coordinate locations of the original data sheet which is nice. I included all of the example input files that the author included in a different folder. I have a comparison file in there comparing the NACA 65A009 data points from the code to those of the original document.

Anthony

update; have since determined it is best to use the data points from NACA RM L51I12 for the 65A009 definition.

Attached is another update for PropDesignGeo script, which includes mirror of the curve.

The mirror code is very similar to the arccenter code.

One peculiarity is that the Base pt / End pt line appears on the screen, until Done or Cancel are selected. ?????

// To Mirror curve, using the CoordinateFrame:
// Create a point Object list, of the Curve points.
var CurvePtList = factory.calculate();
// The same Coordinate leFrame with same Base pt, pt_leArccenter, can be used.
var factoryMirror = moi.command.createFactory( 'mirror' );
factoryMirror.setInput( 0, CurvePtList );
factoryMirror.setInput( 1, leFrame );
// Set End pt. (pt on y axis works fine.)
factoryMirror.setInput( 2, pt_teArccenter );
// Save the current curve pt mirror.
AirFoilfactories.push( factoryMirror );

Hi Brian,

> One peculiarity is that the Base pt / End pt line appears on
> the screen, until Done or Cancel are selected. ?????

Some geometry factories add additional decorative geometry to the geometry database which for the regular commands help to kind of illustrate what is happening. If you run the regular Transform > Mirror command you'll see that when you go to pick the 2 points for the axis line, there is a line drawn between the points basically marking the mirror axis, but that line goes away when the mirror command is finished - that line is the "UI geometry" that the mirror factory is creating.

You can disable the creation of UI geometry by calling the disableUIGeometry() method on a factory, so try doing something like adding this line:

factoryMirror.disableUIGeometry();

immediately after you create the mirror factory.

- Michael

hey brian,

i wanted to give you a heads up that there will be one last change to the prop_design_geo file (and prop_design). i scoured the ntrs site and found several definitions for the naca 65a009. i evaluated them all. i also evaluated the pdas codes. i found one particular set of data from naca that meets all the criteria. moreover:

- the geomtery data document is that which is referenced by the performance data document
- you can fit a through point curve through all the points
- the leading edge can be defined the way burrman and steve desired. however, it is also defined as a circle by naca. both definitions for
the leading edge are now in complete agreement.
- the joined curves can be swept to make a blade without any lumps

the definition that seems to be the right one can be found in naca document:

1951, NACA RM L51I12; Milton D Humphreys, Pressure pulsations on rigid airfoils at transonic speeds

the performance data is in naca document:

1957, NACA RM L57F05; Charles L Ladson, Two-dimensional airfoil characteristics of four NACA 6A series airfoils...

the best historical references as to how the ordinates were obtained is in the following two documents:

1931, NACA Report 411; Theodore Theodorsen, Theory of wing sections of arbitrary shape

1945, NACA Report 824; Ira H Abbott, Summary of airfoil data

however, no one actually shows how they calculated the points specifically. this was done in a time before computers and calculators. so we are talking slide rules and charts. the math is intense. it would take a huge effort to duplicate the work. thus i am using the ordinates as they are shown.

please give me a day or two at the most, to get you a complete update. this will include an updated screencast.

thanks,

anthony

Edit; what was PROP_DESIGN_GEO is now PROP_DESIGN_XYZ. PROP_DESIGN_XYZ is a part of the PROP_DESIGN.zip download available on my website. The latest MoI example screencast can be found on my YouTube page. Here are the links:

http://propdesign.weebly.com/

http://www.youtube.com/user/propdesignsupport/feed

hey brian,

i tried out your latest script and its looking great. the best one yet.

anthony

Thank you very much Michael for the information in your last two replies.

Adding (factoryMirror.disableUIGeometry();) to the script, just after the setInputs, was successful.

I'm trying to script a non-interactive arccontinue. Also trying to script a non-interactive conic, which seems to invole similar problems.

The documentation of Dave Morrill does not mention conic, and for arccontinue, just mentions start and end points, without the curves.

The points need Bind or Snap to the associated curves, which I have no idea how to do non-interactively.

Somehow pointpicker gets bound to 4 conic factory getInputs?

Conic getInput(0) ........Start point.
Conic getInput(1) ........End point.
Conic getInput(2) ........Apex point.
Conic getInput(3) ........Through point.
Conic getInput(4) ........rho value.

Hi Brian - I don't think it will work to make a non-interactive arc continue, since the arc continue factory is set up to work with an osnapped point as its first input.

That's another variety of point (IMoiPickedPoint) that is generated by the point picker, in addition to containing an x,y,z point in it it also contains a list of snaps that were active for the point, and the arc continue factory finds the curve to be tangent from by going through those object snaps.

There is not currently any way to set up a "picked point" other than having it generated from a pointpicker pick, so I don't think that is one that you will be able to automate currently.


Conic should be possible to script though - the inputs what you wrote, you need the first 3 inputs set to points (these can be regular x,y,z data points), then set either the 4th input (with index = 3 since they start at 0) to a point for the "through point" or instead of that you can set the 5th input (with index = 4) to a rho value which is a floating point number.

If you want to specify a "through point", then leave the rho value completely unset, and if you want to specify a rho value instead then you can leave the "through point" input completely unset. Let me know if you still have problems with it.

- Michael

also, if worst comes to worst brian I can add back in the tangent points and you can do the le arc as you were. i would have to add in a bunch of other points though to fill out the conic part of the curve. but its not that big of a deal, if you hit a road block with the current method.

Thank you very much Michael.

The arccontinue did work nicely on the trailing edge, interactively. Instead I'll measure the distance with MoI later, and
do 3pt arc instead.

The conic is a pretty neat curve for the leading edge. I'll try later to see if I can locate the tantan point.
Or just interactively find out the rho value, and then use that in the script... "simple"...

Edit, the le rho value is stated by MoI interactively, as 0.42609.

I was working on a new version for PropDesignGeo, January 5 2012, dropping a lot of "unnecessary" points, with conic le, and arc te, and
fixing up a join factory which I hope will work...