there seems to be something odd about a few of the airfoil positions. i'm looking into it now. but I posted the file and associated screencast. it may help. let me know if you have more questions. it looks like it's going to take awhile to dig into this on my end.

I think there may be some bugs in xyz. I checked a few of the angles for the model in question and they don't match what they should be. It seems like the le and/or te rails may be incorrect. I'll keep working on it.

here is the swept computer case fan example. it's setup to the default cartesian reference frame. I ran into a rhino issue when doing it. so i'm going to go back to the example you mentioned and see if it was rhino messing up again. I came across a really weird orient problem. some of the airfoils came out right and a bunch came out wrong. so I had to redo them to get them setup right. so it maybe that oddball angle was a rhino problem. i'll keep working on it. but the attached file may answer your question better. everything appears in order with this model.

hi karsten,

so I made some errors creating the last two airfoils in the model I sent you for the a400m blade. I have it oriented much better now. the angle of attacks match. there isn't that odd angle showing up. however, the sweep isn't matching up exactly. so I still have to look into it a little more. I found you can use the 2 rail sweep going to a point with multiple cross sections. to smooth it out I skipped a few of the cross sections around the kink. the solid looks a lot like the one I usually get using just the first cross section. I also curve fit the rails to work out the kink, as mentioned in the video. so it's much better now. there may not be an issue with prop design. but i'm still not sure. I am seeing a much smaller difference. at least it's not a huge difference like I was getting.

hi karsten,

ok. so there were some rhino issues with my first attempt at the a400m blade. I left the links up to the file and video. However, I attached a new model and video to this message. The model seems to be accurate now. The video goes over the model. The only thing I see is that the sweep measurements are based off the te in this case. basically the sweep measurement is bouncing from various places. some models it would be the le, some the span, and some the te. this happened with the 10th anniversary update. I basically have to choose if I want the model to bounce around or the sweep measurement to bounce around. I thought it was better to keep the model from bouncing and hadn't realized the affect on the sweep measurement until now. the sweep seems fine it is just how the measurement is done that is changing. so it's probably something I should mention in the documentation. I don't think any changes to the code are needed right now. it is pretty confusing though.

anthony

Hello Anthony,

Thank you very much!
I got it. I will try to correct the positioning of the profiles tomorrow.

Karsten

yw karsten. i'm concerned I created an issue with certain chord distribution options. the sweep should really be defined at the aerodynamic center for all chord distribution options. I was surprised to see that wasn't the case on the a400m. I suspect options 3-5 are messed up. I'm not entirely sure how to fix that right now. hopefully this won't mess you up too much. if I have to make a code change then I also have to make new input files etc... so the example geometry may change slightly. I have to figure out what's going wrong first. seems like I fixed some things only to break others. i'm really glad you brought this to my attention. for now stick to options 1 and 2 and you should be fine to use the total sweep angles output by the code.

@Barry,

It seems something is wrong with the email system. I'm not sure if this is what you looking for. Please replace the links for the csv files and adjust the extrusions.

Have a nice day
Karsten

hi karsten,

I finally made some progress understanding that bug. I think ultimately nothing is going to change as far as for you. I just need to make some changes so the analysis is correct. Unfortunately, understanding the angles is pretty difficult. More so than I thought. I will have to make some pictures and things to try and explain it for the documentation. But basically the total sweep angle is measured in the top view (x-y). It would be about the local z axis of each cross section. In the videos I was saying the global z axis but that's not the case. So if you are using the total sweep angles from the file that is how to use them. I will have a new version of PROP_DESIGN out at some point but I don't think it will change much from what you are seeing and dealing with.

although on second thought. I can now compute the total sweep angle at the aerodynamic center. so I can output it as well. that may fix the whole mess of different reference points. In that case, you could measure everything from the ac. which is how it's supposed to be. i'll see about doing that. not sure what will happen. but i'll get back with you.

hi karsten,

I got the bug fixed. you can now use the angle of attack and total sweep angle files at the aerodynamic center, as was always intended. I checked them out using the a400m model you asked about. there is an updated version of prop design on my website. download that. all the input files were updated as well. so re-run the a400m example. I posted the file I talk about in the screencasts. the links to the updated answer to your question are here:

rhino 5 3dm file for the a400m example; edit - this file was replaced with a more detailed version. the link is in a later post.

screencast part 1; https://youtu.be/lJ7FFXkQr9c

screencast part 2; https://youtu.be/mQMdhpCeoZA

screencast part 3; https://youtu.be/Ns2GiYCnL80

I deleted all the old files and screencasts that I posted in previous forum messages. let me know if you have any more questions.

Hello Anthony,

I had some problems with flipping coordinate systems for clockwise and counterclockwise rotation. I think that I solved it now, but I have to download and compile your updated software. What I saw while testing the script for A400M and Predator example, is that the Profile A is on top for A400M and on the bottom for Predator. For a symmetric profile no problem. Do you use also asymmetric profiles in your software or am I generally wrong? Problem with my script or my interpretation of the data? I don't know.

Do you have the possibility to test the node scripts already?

Have a nice day
Karsten

hi karsten,

yes the airfoil is symmetric. I believe you are right that a and b will switch depending on the blade. that isn't something that affects me but if it is messing you up, let me know. I know in the code there are four outcomes that I had to program. clockwise, counter-clockwise, swept forward, and swept back. so you may run into that as well. I don't have moi yet. I was waiting for v4 to come out, to try and make the switch easier. I don't know anything about the node editor or all of max's custom scripts. I have been reading the forum for years though. so I kind of know what all has been going on. but I haven't used any of it. I'm sure i'll have lots of questions once I get started.

Hello Anthony,

if the profiles always symmetric - there is no Problem. I use only the rails, span and profiles in the script.

>>>> I'm sure i'll have lots of questions once I get started.

I think that's a forum is made for.

Have a nice day
Karsten

Hi Anthony,
can you take a look at the attached curves that I produced with the node editor to see if they are what you require.
At the moment I produced the 2 sets with different nod files with the node editor but will see if I can incorporate both into one nod file.

Anyway hope this helps.
Barry

hi barry,

thanks for continuing to work on this. i will take a look. i downloaded the file and right away noticed something odd. the second airfoil from the origin seems rotated 90deg out of phase to the rest of the airfoils. i'll continue to look at the file though. the rest seem like they could be right.

hi barry,

the swept fan blade appears to be more inline with the needed outcome. it will take me some time to do exact comparisons. but i could do a two rail sweep on the geometry you provided and the airfoils visually seem like what you would want. the a400m blade though has some problems. the second airfoil in is about 90degs from the others. but none of the airfoils seem to have their sweep value. when i try a 2 rail sweep the blade is wavy at the tip and the surface is very heavy. it's really slow in rhino. it seems like the airfoil curves might have too much definition if that makes sense. i didn't seem to have that issue with the swept fan blade you provided. but i will work on my manual models so i can do more of a comparison for you. but it seems like you are getting close. i can visually see you have them onto cylinders which is great. and you have two kinds of profiles which is really useful too.

here is a link to the updated a400m model. there is tons of info in there you can use to compare to. i manually created everything in the file. when doing the 2 rail sweep i ignore two of the profiles that deviate a lot from the curve fit rails. this is to smooth out the wavyness. this is kind of a bad example to use for comparisons. but since you picked it, i went ahead and detailed the model the best i could. i will work on the swept fan blade next. that one is a better test case.

Hi Anthony,
your right the Airfoil profile was reversed I have corrected it.
The kink 4th foil from tip the curve is not a thro points curve in that area and doesn't match the airfoil profile tip.
I think you showed that issue in one of your screen casts.
If you have another example I can trial that would be helpful.
Cheers
Barry

hi barry,

i think we posted at the same time. see the post above this one with my reply. also, i updated the swept fan blade. you asked about this earlier, but i didn't have it completed at the time. this should help with comparisons as well. all the info to compare to should be there now. everything was manually created. there is a bit of extra info you probably don't need in there. i had also did fea on the model to check some other things with PROP_DESIGN. everything wrt PROP_DESIGN seems to look alright the best i can tell.

so this model and the one from the previous post are what i would use to compare to. i will import your geometry into the files and see how it looks.

update 1; so it looks like maybe we aren't using the same input files for the swept fan blade. your geo doesn't match up with mine. on the a400m the sweep seems to be missing on your geo. but you are getting close.

update 2; doing this comparison on the a400m blade shows there still may be an issue with PROP_DESIGN. chord distribution options 3-5 seem like they are causing some blade sweep when measured at the quarter chord. i thought i fixed this but even the non-swept stations look like they may get some sweep just due to how the geometry is constructed. i will have to look into this some more.

i just updated the link to the a400m file. prop design has been updated as well. i made another attempt at fixing the bug related to chord distribution options 3-5.

i don't know if it's possible for you to do, but if you could script the addition of dimensions for the radius, twist, and sweep angles, that would make checking your files a lot easier. you could then check them against the xyz output files. but you should now have everything you need to check the automatically created files for the a400m example and the swept computer case fan example.

i haven't checked my fix for chord distribution options 3 and 5 yet. hopefully it works ok without more bug fixes. i will look into that next. but it shouldn't affect the two cases you are running now.

update; I finished checking cds 3 and 5. found no issues. so hopefully all the bugs are fixed now. this bug was the same as the last one. all i did to fix it this time was apply the previous fix for any sweep angle. before i applied it only for sweep angles greater than zero. i hadn't realized that when you define zero it gets changed for cds 3-5.

Hi Anthony,
attached latest results of the test fan model and the A400M.
On the A400M I used the point files to generate the Span , A & B curves as these had no modification in the tip area.
The result seems to reduce the kink at the tip end also I tried the network command using the Foils plus A & B curves this again seems to give a smooth result.
I have used the cord distance between the span curve point & B curve point as my scaling factor is this correct ?
Let me know if there any problems with the attached files.

Barry