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Jan 15, 2019, 01:43 PM
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Dirty Dee's Avatar
Quote:
Originally Posted by too_oblivious
Printing them might be a hassle due to tolerances between printers but I would like to print this in ABS so I am hoping that acetone welding will melt them enough to provide a snug fit.
Best part of ABS. All of my parts are super snug fits, but I need to be careful when pushing the parts together, because the excess ABS slurry gets squeezed out a the mating surface and it can splatter onto your clothing and face (wear protective eyewear).


Quote:
Originally Posted by too_oblivious
Unfortunately I do not have a printer yet. I have made these at largest a 7" section (the nose) and from here on out I will be trying to keep to a 5" standard to fit smaller size printers. It might be too small for a ~52" wingspan but I have yet to model the wing sections which arguably will be the most taxing to slice up for printing.
When I was slicing my wings, I performed the slices at spots that made sense (flat surfaces, hinge locations, etc), which usually limited them to ~120-150mm sections. My ~3ft wings each have 10 individual sections.


Some questions on you modeling:
I notice you added fillets to the structures under the outer skin. You can probably omit those as the printer will have to do extra movements to fill in the small voids, and it will also reduce the total feature count in the part file.

Are you modeling the whole airframe in a single part file? Be careful doing this as the more features you have, the slower the file will get, and the longer it will take to edit an individual feature. On my A330, my wing section is getting a bit tedious to work in due to the amount of features in the part. If I ever have to edit a feature, it takes a solid 20 seconds for the feature to become editable, and then saving it is laggy as well. I think I have around ~700 individual features for the wing alone.
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Jan 15, 2019, 02:04 PM
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Quote:
Originally Posted by Dirty Dee
I notice you added fillets to the structures under the outer skin. You can probably omit those as the printer will have to do extra movements to fill in the small voids, and it will also reduce the total feature count in the part file.
There are chamfers modeled throughout the part to smooth transition from a 2 perimeter wall to the fuselage ribs. The do add the total print time but I think it will be worth it to reduce stress concentrations. If the fillets you speak of are the little round stringers on the skin in between where the carbon rods will be inserted those are hollow to two perimeters to stop those extra movements. I have little thin wall 3d printing experience so if the printer will still try to fill in those I appreciate the information!


Quote:
Originally Posted by Dirty Dee
Are you modeling the whole airframe in a single part file? Be careful doing this as the more features you have, the slower the file will get, and the longer it will take to edit an individual feature. On my A330, my wing section is getting a bit tedious to work in due to the amount of features in the part. If I ever have to edit a feature, it takes a solid 20 seconds for the feature to become editable, and then saving it is laggy as well. I think I have around ~700 individual features for the wing alone.
Thankfully I am doing submodels throughout. The full plane file is an assembly file just to make sure everything fits together and "pre-assemble" the prints analytically.
Jan 15, 2019, 02:39 PM
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Dirty Dee's Avatar
Yea, I was speaking to the chamfers.
Jan 15, 2019, 04:31 PM
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Dirty Dee's Avatar
Here are some more reference drawings to add to your arsenal.
Jan 15, 2019, 05:24 PM
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Thread OP
You sir are a gentleman and a scholar! Whole new take on accuracy now! Thank you so much!
Jan 26, 2019, 12:26 AM
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3rd time is the charm


Thanks to the wonderful inputs by DirtyDee with amazingly detailed plans I have been off to the races redoing everything again. I was not quite happy with the previous iterations and now I have so much joy with a model that looks right. In addition I have created 2 models for the price of one! the 300 and 100 series aricraft only differ in fuselage length as far as I can tell. I might have gone overboard on the structural components, but this is my first 3D printed airplane and I don't quite trust layer boundaries for flight loads. Tomorrow I should have the wing cradle all modeled up and hopefully by the end of this weekend the fuselage. I have preliminary airfoils chosen and they will be the aquila airfoil and an eppler 855. Some XFLR5 calcs will need to be completed to determine the negative angle for the horizontal stabs. With a decent ~7-10 degrees of washout at the tip, I am hoping for a gentler airplane with minimal tip stall. Wing loading calcs are to come soon since I am trying to limit myself to a 52 in wingspan since that is the largest size I can accommodate. Stay tuned!
Jan 26, 2019, 08:32 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Good you are paying attention to those items. I'm building a Martin 4-0-4, and learned things the hard way. Not by crashing (it hasn't flown yet) but not paying attention to critical details and finding out later I didn't do things right. A lot of do-overs for me, but yet a great learning experience.

I really envy you guys who have the CAD thing figured out. I just can't get wired up for that. Maybe in retirement that can be a bucket list item.
Jan 26, 2019, 06:53 PM
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Thread OP

solidworks issues


I was able to make up the guides for the center wing cradle today but unfortunately when it came to lofting the feature my guides were not playing nice. After a few frustrating hours I gave up. Look at another day. If there are any hints or tips for solidworks that people know please feel free to help!
Jan 26, 2019, 07:42 PM
Purdue Engineering
Rocketman1092's Avatar
Can you post a screenshot of the loft operation that's failing? That might help shed some light on what's going on.

Also, in this sort of situation it may make sense to loft the cylindrical portion of the fuselage and the wing box separately to be combined afterwards.
Jan 26, 2019, 07:53 PM
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Dirty Dee's Avatar
Check my solidworks blog post. I tried a similar approach with guide curves like in your picture but it wouldn't work. I made a separate solid body and tweaked the splines until the intersection of the body against the cylinder matched close to the original curve
Jan 28, 2019, 10:41 PM
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Thanks for all the suggestions and offers to help! I really appreciate it. I was on a little holiday this weekend so not much progress, but after sitting down and taking a look at the guide curves, it was because I did not have enough to constrain the geometry correctly. So I plastered the heck out of the wing cradle to where a birdcage met a fishing net, with 3d sketch guide curves and VOILA! Had to extrude the fuselage in two parts because of a thin feature that would fail. Finally.
Jan 31, 2019, 09:37 AM
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Thread OP
I do not know if this is correct so anyone feel free to jump in, but I was doing a little research on the landing gear configuration for the CS-100/CS-300 or A220 for pedandics, but it seems it does not have any main gear doors like the 737. If anyone can find a good picture showing the configuration I will owe you one!
Jan 31, 2019, 09:59 AM
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Dirty Dee's Avatar
I found you sometimes have to think outside the box, and look in places you normally wouldn't for reference images

FYI, "MLG" is a good search term for Main Landing Gear


I trimmed out some of the document to fit the 3MB limit, but if you search for the document name online, you can find the full document.
Jan 31, 2019, 12:32 PM
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Thread OP
You sir are a magician, I need to learn these ways and acronyms. My Google searching is nowhere near up to snuff lol. All I know is (search entity) -(filters) to get better results. Thank you so much!
Jan 31, 2019, 08:09 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Quote:
Originally Posted by too_oblivious
I do not know if this is correct so anyone feel free to jump in, but I was doing a little research on the landing gear configuration for the CS-100/CS-300 or A220 for pedandics, but it seems it does not have any main gear doors like the 737. If anyone can find a good picture showing the configuration I will owe you one!
I'll ask my son to take a look when he gets a chance. They aren't regular HSV equipment, and they may not be back anytime soon as they may already be running their regular routes.

Do Bombardier or Airbus have drawings of pics on their web site?


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