wow that's bizarre. no definitely not correct. i just posted the update. i also updated the a400m example. now the straight blade has the same amount of total sweep. but does it without any blade sweep. this gets rid of the kink. but you loose about 2% propeller efficiency. however, i don't feel like you can really build the bent blades in a way that would perform as predicted. so the straight blade with airfoil sweep is probably the better way to go. i have also been thinking about any kind of sweep and whether or not projecting onto cylinders makes sense. for a purely straight blade with no sweep, so chord distributions 1 and 2, the idea of projecting onto cylinders makes sense. but once you add sweep, i'm not sure it applies anymore. so i just wanted to make sure you had the option to apply the projection or not. you'd have to build and test to see how they work.
for the bug you found with rail points, can you provide the file or example you ran. i mainly need to know the number of points to define the blade, the mesh density multiplier, and the number of tip steps. that way i can see what you are seeing. but definitely sounds like something is messed up there.
besides updating the a400m example, i found a bug in opt that was changing one of the tolerance values. i changed one of the optimization criterias slightly as well. so it's now working the way i expected it to. both input files for the a400m changed. the bug was causing the shaft power target to be voided. now both blades are drawing the specified shp.
Hi Anthony,
in the photo you will see the difference I have in your new projected curves and my calculated ones.
It appears that your projected curves have been rotated back and no long lie on the cylinder is this correct?
It's no problem for me to allow for this.
Barry
there are four profile positions in total. for the file in question, if you turn on the 'imported geometry layer' and the 'projected airfoils' layer you will see all four positions. the 'comparison geometry' layer i just copied over what it seemed like you were outputting. to make it easier to compare to your work.
i want to update this model again, to match the current version of prop design. however, i'm thinking it would be better to use the new a400m straight blade geometry. it doesn't have that bend at the tip but performances about the same. in reality, i don't think the bent blade would actually achieve the predicted performance anyways, due to the bend. there really isn't a way to manufacture the bend that would match prop design. unfortunately, this is a case where prop design modelling the blade as a line is an issue when you try to go to reality.
i can still work with the bent blade if you want. let me know what you would prefer.
for karsten's question. i can't duplicate what you are seeing. i get 64 points for all the rails, using the default settings of 13, 50, 1. let me know how you were seeing those odd results. just to make sure you weren't talking about the significant digits, i checked the source code write formatting and they are all the same. G25.17 is the default format for the output numbers.
i had one thought on the issue you mentioned. i'm looking at xyz output. i don't know if you are looking at some of the files in the two test cases. i think i saved some of them with spaces i added. the added spaces helped me check the dimensions used in the examples. not sure if that is what you are seeing or not. let me know.
Hi Anthony,
attached latest curves created with node editor for the A400M.
They match the manual ones you created. If you require the other angled options let me know.
looks like you nailed the position and everything. the only problem i see is that when i do a 2 rail sweep using your airfoils they have more definition than the ones i made. so the surface comes out on the heavy side. not sure how you are ending up with more control points than me. even mine come out a little weird too. mine has something to do with the projection. once i do the projection the curves are no longer defined the same. but there's nothing i can do about it. on yours, they come out with even more points than mine. but it seems like you worked out all the bugs.
just as a reminder on features, can you also do the same thing without them being projected to cylinders? so the airfoils would be in the same place as you have now. that would be a useful option.
also, many posts up there was a list of various profiles that would be useful to have. lastly, if at all possible to automate adding in the dimensions using max's dimension script until michael gets his own dimensions going. in the test file i have the dimensions so you can see where they would go. mine are laid out in a bit of a mess. rhino doesn't have a way to move them that i know of. so if you don't arrange them right you have to do them over. so i just left them all messy.
but even what you got now would still be a huge time saver. it takes a really long time to get to the point you have automated. so you have saved a lot of work for people.
I've made a screencast of what is possible. Some things are not implemented at the moment - erasing the high density of profiles, patch the end of the blade, ...
For the patch at the end I have an idea, that i've tesed manually.
But I hope you will get an impression of what is possible.
Have a nice day
Karsten
p.s.: Sorry for my english - The slang is called denglish:-)
Hi Karsten,
Interesting video and I’ve got a couple of questions if you don’t mind.
The things I would like to add to my nod is how you fillet and blend the Airfoil.
At the moment my method require doing this manually then joining and naming. I would like the blend to be automatic and the fillet to be adjustable.
Your new blend node does it use the point on the ‘A’ curve as it’s peak position?
Cheers have a good weekend.
Barry
thanks for the video, it was great. that's really quite amazing. i think this will be extremely useful to a lot of people. creating new rails is a great idea. that's something that was too much of a pain for me to do manually. it's interesting how much you can automate. you're english is very good. you reminded me of a professor i had in college, dr. ying. everyone said he spoke yinglish. no one could understand anything he said. so i was worried at first. but your english is fine.
seems like you got all the major issues dealt with. i look forward to playing with this in the future.
if i understood you right, in your last post you were talking about working on doing the root fillet. the file you wanted a link to awhile ago has some retention geometry in it. you could use a shape similar to that to attach the blade to, then try to fillet it. i have found this geometry to be about the best to go with. it fits the most blades in it. i have been manually making it, as it varies blade to blade. i'm not entirely sure if you could automate it. i'm not sure of exactly what factors go into sizing it. i found rhino messes up the geometry a lot in subtle ways. the best way to get rhino to accurately make it was to extrude a whole cylinder and then do a boolean split with those funky red curved surfaces. anything else i tried would be malformed. which is typical rhino. that's why i am looking forward to switching to moi. but this should give you an idea of what sort of retention to connect the blade to. unfortunately, simple pie shaped pieces often don't allow you to fit all the blades. so you need that weird cut to get a lot of blades to fit onto a hub. this is the same link as before, just posting it again for convenience. let me know if you have any questions.
Hi Anthony,
not sure what you mean that's in the file as it's the fan profile and I want to add the conic fillet to the tip and the 2mm fillet to the tail
of the A400M profile ?
Anyway regarding your questions in previous post I have added the flat profile plus the option of the 2 positions of the curved profiles.
I tried a rebuild of the Profile curves to see if that would reduce the surface points but no luck I think it's the way Moi works.
The option of adding dimensions within the node editor isn't possible as far as I know.
You mentioned other profiles posted on this thread for me to trial but I could not find them so if you have some or just points files can you send them to me.
Cheers
Barry
i misunderstood. i thought you were talking about the root fillet. i see you mean the le ellipse and the te arc. if you were attempting the root fillet, that was the geometry i was mentioning. it's ok about the extra points. i was thinking that could also be due to differences in tolerances. i spent quite awhile messing with rhino tolerances. and eventually went with what they said in their help. i know changing those affects the results a lot. so it's probably just a difference in tolerances. but maybe also some difference in methods used. as long as it works, it's no big deal. when i was using higher tolerances in rhino, the surfaces would get so heavy it made it hard to rotate pan models etc with lots of blades. so that was my only fear with you having more definition than i had.
i think on the profiles, i was just referring to the list i made in an much earlier post. i think those were:
the naca airfoil (has an elliptical le and a small arc at the te)
the naca airfoil with a user defined te radius (needed for manufacturing something that can handle the operating stress)
the naca airfoil with the le made with straight lines and the te going to a point (useful for fea)
a flat plate cross-section with user defined le and te radius
i can't recall if there was another option i mentioned. but these would be sufficient i think.
i've been working with the a400m example geometry. i wanted to try a dovetail turbofan retention with a traditional fixed pitch propeller. i also wanted to look at hollow composite blades. i made a lot of updates to the file i shared previously. the main thing to be aware of for what you guys are working on is that the surface i get from rhino is worthless. you can't do anything with it. i ended up having to go back to the way i was doing the blades before. which is just a two rail sweep using the base profile. it's not accurate to what i want but it's the only surface that you can actually use for anything later on. if the surface is valid you should be able to do things like create solids, calculate volume, export it to mesh, etc... you can't do any of that with what rhino is creating using the projected airfoils and 2 rail sweep to a point. i found you can't go to a point at the tip either. that will corrupt the geometry. so i trim the geometry at the next to last point.
the geometry for you to compare to is still on the comparison geometry layer
there are a bunch of fea files you probably don't need. but i just have them there because it's how it's stored on my computer. they are for use with mecway.
one interesting note and something i know from my past experience. an aluminum blade is stressed to the point that it supports the weight of several african bush elephants, over 35,000 lbf in this case.
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