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Cory Puuri
08-01-2016, 02:43 PM
After you create a design and want to share it, load it to GrabCAD and tag it as "EAA". Then, post a reply to this forum thread and link it here. Thanks!

Link to GrabCAD: https://grabcad.com/library/software/solidworks

EAA.PRTDOT (https://drive.google.com/file/d/1HFWvcJmv_1EYxmqWDELHB8Mg4wfctAOP/view?usp=sharing) - If you want SOLIDWORKS to be configured for aircraft design purposes, Tom Kreiner created this part that you can convert to a template. Steps to using it: 1) Click the link and download, 2) Open the template and save it (File / Save As), 3) Click YES to Delete the empty sketch, 4) in the first Drop Down Menu at the bottom of the Window select "Part1" (or whatever name that appears) and enter "EAA", 5)in the second Drop Down Menu select "Part Template", and 6) click Save button. Going forward, select this EAA template to pre-load SOLIDWORKS' aircraft design settings.


Below, I will repost links to common parts.

(http://www.mcmaster.com/)Fasteners (McMaster) (http://www.mcmaster.com/) - a) choose the product in the McMaster catalog by number, b) download a 3D CAD file by either SOLIDWORKS (might not work in EAA Maker Edition) or STEP option, c) [if you choose STEP] say no to "checking" or "feature recognition", d) save the part to you library under Fasteners, and e) consider suppressing the thread cut feature to reduce the part complexity for file size. (The detailed geometry of these parts may slow down your system if you incorporate a lot of them into a complex design.)
AN Fittings (Swagelok) (http://oem.cadregister.com/asp/PPoW_Entry.asp?language=GB&company=SwagelokCo)
Tubing (http://vr3.ca/documents/VR3Weldments.zip) - This is a ZIP file provided by VR3 that includes various sizes of tubes that could be used in tube and fabric aircraft designs
Traceparts (http://www.tracepartsonline.net/(S(3zbwbi5ibxdagezywhhcmnqf))/content.aspx) - multiple 2D and 3D parts catalogs in one location
Common Biplane Parts (http://79ft.net/pages/solidworks-models.html)
SOLIDWORKS File Sharing Site (http://www.3dcontentcentral.com/) - this can be challenging to search as it lacks the tagging of GrabCAD
3D Content Central (https://www.3dcontentcentral.com/) - The site requires a free login. This is owned by Dassault Systemes, maker of SOLIDWORKS. It isn't as good as GrabCAD for sharing between hobbyists, but there are a lot of manufacturer parts available.

Aircraft
Zenith 750 Cruzer (http://documents.zenith.aero/3d-solidworks-model.html) - eDrawing, courtesy of Zenith Aircraft
DHC-1 Super Chipmunk (https://grabcad.com/library/dhc-1-super-chipmunk-n7dw-1)* - courtesy of Mark Meredith
MC-15 CRI-CRI (https://grabcad.com/library/cri-cri-complete-1)* - courtesy of Osvaldo de Jesus
Bowers Flybaby (https://grabcad.com/library/bowers-flybaby-1) - courtesy of Max Witt

Airfoil
UIUC Airfoil Data Site (http://m-selig.ae.illinois.edu/ads/coord_database.html) - This is not a design, but a group of nearly 1,600 airfoil coordinates files that can be pulled into SOLIDWORKS with some work. Check out this forum post (http://eaaforums.org/showthread.php?6884-Post-SOLIDWORKS-Designs-Here&p=58494&viewfull=1#post58494) for more info.

Engines
Rotax 912 (https://grabcad.com/library/rotax-912)*
Dynacam (https://grabcad.com/library/dynacam-aero-engine-1)* - courtesy of Bert van Haren

Panels
Van's (https://www.vansaircraft.com/public/downloads.htm) - stored as DXF files. Here is an explanation of how to convert to SOLIDWORKS (http://eaaforums.org/showthread.php?7673-RV-panel-importing-Vans-dxf-drawing-Convert-Entities).

Avionics
Dynon (http://www.dynonavionics.com/drawings-cad-models.php) - DXF 2D and IGS 3D "Sand-filled" solid models
Garmin (https://support.garmin.com/support/manuals/manuals.htm?partNo=010-00G3X-00) - DXF 2D and STEP 3D "Sand-filled" solid models

Fabrication
Lightning Hole Tool (https://grabcad.com/library/sheet-metal-lightening-hole-forming-tools-1) - courtesy of Mark Meredith
Tube Marking Tools and Other parts (https://drive.google.com/drive/u/1/folders/0B6fcluqN5u3oOGtnc0llamZORmM) - courtesy of Rainbow Aviation's Brian Carpenter (http://www.electricmotorglider.com/2016/08/icom-ic-a6-ic-a24a-radio-mount-3d.html) visit his EMG site for more info and check out his EAA Hint's for Homebuilders (http://www.eaavideo.org/video.aspx?v=5232453840001) video on 3D printing.EAA Workbench (https://grabcad.com/library/eaa-standardized-workbench) -

Other Parts
Radio Mount: Icom IC-A6 / IC-A24A (https://drive.google.com/drive/u/1/folders/0B6fcluqN5u3oekhEeGFrRGZvMms) - this mount is courtesy of Rainbow Aviation's Brian Carpenter (http://www.electricmotorglider.com/2016/08/icom-ic-a6-ic-a24a-radio-mount-3d.html) visit their site for more info
AN Bolt (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN4 Aviation Hardware Pack (https://grabcad.com/library/an4-aviation-hardware-pakage-1) - courtesy of JayMan_5000
AN310 Castle Nut (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN315 Plain Airframe Nut (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN316 Jam Nut (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN365 Elastic Stop Nut (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN381 MS24665 Cotter Pin (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN392 Clevis Pin (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN393 Clevis Pin (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN430 Rivet (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN470 Rivet (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN490 Rod End (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN665 Clevis Terminal (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN960 Washer (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
AN970 Wood Washer (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KP3 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KP3A (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KP3L (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KP4 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KP4A (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
KSP3L (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
MS20426AD Rivet (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
MS21042 Stop Nut (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP3H5 Assembly (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP3H5 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REPB3N2 Assembly (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REPB3N2 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP4F5 Assembly (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP4F5 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP4H6 Assembly (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
REP4H6 (http://79ft.net/pages/solidworks-models.html) - courtesy of EAA members, Bill Rose and Fi Fomichev.
Carling Series V Rocker Switch Mounts (https://grabcad.com/library/carling-contura-mouting-panels-2) - courtesy of Scott Flugum
Wing Tip Light Mount for Panther (https://grabcad.com/library/wing-tip-light-mount-1) - courtesy of Scott Flugum
Scott Tailwheel Assembly (https://grabcad.com/library/scott-3200-tailwheel-assembly-zip-1) - courtesy of Mark Meredith
DHC-1 Super Chipmunk Flap Assembly (https://grabcad.com/library/super-chipmunk-flap-assembly-1) - courtesy of Mark Meredith
DHC-1 Super Chipmunk Main Gear (https://grabcad.com/library/dhc-1-chipmunk-main-gear-1) - courtesy of Mark Meredith
Timken Roller Bearing (https://grabcad.com/library/timken-roller-bearing-1) - courtesy of Mark Meredith
Aero Vent (https://grabcad.com/library/aero-vent-1) - courtesy of Igor H. (forums aka "supik")
Cessna 182 Trim for Light (https://grabcad.com/library/cessna-182-trim-light-cover-1) - courtesy of RM Lewis Jr.

After you create a design and want to share it, load it to GrabCAD and tag it as "EAA". Then, post a reply to this forum thread and link it here. Thanks!


*Not an official design; so, dimensions and weights may be inaccurate and the provider may not have permission to reverse engineer and share such models. Designs are shared for informational and educational purposes only.

wltrmtty
08-01-2016, 06:05 PM
FWIW, I won't be using it for designs, but I will be using it to recreate detail parts for my Pober Junior Ace drawings to be used as CAM files for waterjet fabrication. Perfect timing!

Cory Puuri
08-01-2016, 07:00 PM
FWIW, I won't be using it for designs, but I will be using it to recreate detail parts for my Pober Junior Ace drawings to be used as CAM files for waterjet fabrication. Perfect timing!

Very cool! You can share parts, too. Maybe you can group all of them into one forum post with links.

I did want to add that if you assemble the parts in an assembly you can identify areas where moving parts may strike each other in unintended ways so that you can modify them and correct problems.

Jeffrey Meyer
08-01-2016, 11:00 PM
.....
I did want to add that if you assemble the parts in an assembly you can identify areas where moving parts may strike each other in unintended ways so that you can modify them and correct problems.

When you're in assembly mode in SW go to Tools > Interference Detection > Calculate.

Jeffrey Meyer
08-04-2016, 01:23 AM
Here is an overhead light fitting designed in SW, 3D printed at home, and being installed on an RV. (Couldn't attach the SW part file - forum attachment file size limitation).

http://eaaforums.org/images/attach/jpg.gif
Designed in SolidWorks

http://eaaforums.org/images/attach/jpg.gif
3D printed at home (apologize for the poor photo quality)

http://eaaforums.org/images/attach/jpg.gif
Being installed on an RV

Jeffrey Meyer
08-05-2016, 05:37 AM
If you're into 3D printing and now that you're an expert (;)) in SW, here are a few design ideas for your homebuilt:

Various grips, handles and knobs.
Pedal covers.
Molds for glass-fiber/carbon composite parts (wheel spats, winglets, fairings, ...).
Holders for smart phones/tablets and portable avionics.
Sunshades for instruments.
Storage hooks for headsets.
Covers for pitot tubes.
Mounts for small personal fans (or the fans themselves).
Coffee cup holders.
3D models of your homebuilt.
Custom (and light) wheel chocks.
GoPro camera mounts.
Air vent openings.

I'm sure there are lots more ideas out there - the sky is (literally) the limit.

cwilliamrose
08-25-2016, 11:28 AM
I am not looking to share this model but several of us do share common stuff -- AN hardware, etc and the link to the library is on the Biplane Forum website. Anyway, the image below is of a Pitts project I started many years ago and will finally be putting on the front burner. This model started out as simply the aileron control system and I was looking to modify the geometry to eliminate the differential travel. I'm using different ailerons so a lot of things changed and the goal for me was to evaluate what the travels would be with stock or near-stock components and then change the bellcrank angle to get identical travels up and down. The aileron system model progressed into also looking at my elevator trim system,,,, then a full fuselage (modeled as-built since it pre-dates Solidworks) with wings. I started this model in June 2013.

I'm working with an engineer on my aileron design and we communicate via email with Solidworks models. Makes life much easier for both of us!

I have been a Solidworks user since 1998 and I see this as a tool to confirm that all the parts will play together nicely. I hope to avoid building multiple versions of parts only to find out I didn't think of all the downstream effects of my changes. The scrap pile should be smaller and pixels are much cheaper than aircraft materials. Beyond that I design the jigs and fixtures used to make some of the parts and some of those have already been built.


5724

AnnaWood
08-27-2016, 06:50 PM
I am not looking to share this model but several of us do share common stuff -- AN hardware, etc and the link to the library is on the Biplane Forum website. Anyway, the image below is of a Pitts project I started many years ago and will finally be putting on the front burner. This model started out as simply the aileron control system and I was looking to modify the geometry to eliminate the differential travel. I'm using different ailerons so a lot of things changed and the goal for me was to evaluate what the travels would be with stock or near-stock components and then change the bellcrank angle to get identical travels up and down. The aileron system model progressed into also looking at my elevator trim system,,,, then a full fuselage (modeled as-built since it pre-dates Solidworks) with wings. I started this model in June 2013.

I'm working with an engineer on my aileron design and we communicate via email with Solidworks models. Makes life much easier for both of us!

I have been a Solidworks user since 1998 and I see this as a tool to confirm that all the parts will play together nicely. I hope to avoid building multiple versions of parts only to find out I didn't think of all the downstream effects of my changes. The scrap pile should be smaller and pixels are much cheaper than aircraft materials. Beyond that I design the jigs and fixtures used to make some of the parts and some of those have already been built.


5724


Very nice looking model cwilliamrose....

cwilliamrose
08-29-2016, 10:03 AM
Thanks Anna! Here are a few closer views;

5749
The bolt is not fully inserted because I wanted to see if it could be inserted past the horn.

5750

5751

5752

5753

cwilliamrose
08-29-2016, 10:52 AM
To illustrate how I use this tool (SWx), I discovered an interference between the wobble pump bracket and the aileron pushrod. The aileron arm on the torque tube was (and actually still is) in the standard location but since my seat is farther aft the wobble pump is also farther aft. The fix will be to move the aileron arm (yes, cut off the old one and install a new one, straighten the torque tube, etc,,,) farther aft on the torque tube. On a stock S-1S the aileron pushrod is not parallel to the spar, mine will be (when I get around to changing it). I wish I had a tool like SWx when I did the initial design work, a mistake like this would have never happened...

5754
As currently built.

5755
Post surgery.

Jeffrey Meyer
08-29-2016, 02:05 PM
To illustrate how I use this tool (SWx), I discovered an interference between the wobble pump bracket and the aileron pushrod. The aileron arm on the torque tube was (and actually still is) in the standard location but since my seat is farther aft the wobble pump is also farther aft. The fix will be to move the aileron arm (yes, cut off the old one and install a new one, straighten the torque tube, etc,,,) farther aft on the torque tube. On a stock S-1S the aileron pushrod is not parallel to the spar, mine will be (when I get around to changing it). I wish I had a tool like SWx when I did the initial design work, a mistake like this would have never happened...


The interference checking tool in SW is certainly one of the unsung heros. Another is the detailed BOM (Bill Of Materials that can be exported as an Excel file) that goes right down to counting the number of rivets (if you bothered to model them:eek:),

I second Anna's motion on the beauty of this model

Jeffrey Meyer
08-29-2016, 02:27 PM
I'm working with an engineer on my aileron design and we communicate via email with Solidworks models. Makes life much easier for both of us!


I'm curious to know if you were able to calculate the weight of the airframe and location of the CofG from this model, and how it compares to the "as built" numbers?

cwilliamrose
08-29-2016, 03:20 PM
I didn't try to do a CG calc, there are way too many things that won't be in the model -- like the right wings :P, welds, hoses, wires, fabric and paint and even a full population of screws/bolts/rivets (yep, I have them modeled). I do weight studies on parts and simple assemblies which helps drive design decisions but I mostly include hardware items to check for clearances. I have seen some errors with the mass properties tool involving ignoring assigned materials so I don't trust it 100%. I have a big weight adjuster -- the engine mount! The plan is to do the engine mount last to nail down the CG using the otherwise finished airframe.

I have used the interference tool on other (work) stuff but this model is too large to deal with, I just make sure things have a decent amount of space between parts visually.

Hey Cory, if you're looking in on this, your PM mailbox is full.........

Jeffrey Meyer
08-30-2016, 02:34 AM
... I have seen some errors with the mass properties tool involving ignoring assigned materials so I don't trust it 100%.

Could you give me an example of such errors? I've had rather good experience with the mass properties tool, but I may have missed errors due to my negligence in checking - more trust than sense :rollseyes:

Jeffrey Meyer
08-30-2016, 02:55 AM
...I have a big weight adjuster -- the engine mount! The plan is to do the engine mount last to nail down the CG using the otherwise finished airframe.


I gecha - Make the engine mount either out of lead or styrofoam depending on where the "as-built" CofG turns out.;)

cwilliamrose
08-30-2016, 07:32 AM
Could you give me an example of such errors? I've had rather good experience with the mass properties tool, but I may have missed errors due to my negligence in checking - more trust than sense :rollseyes:

In a fairly large assembly the total weight didn't seem right and a little digging showed that some of the components were being left out of the mass calculation. I checked that those parts were assigned a material and the properties were correct. It is possible the parts were configured and the individual configurations were missing a material assignment but I didn't go that deeply into it. This was a number of years (and versions) ago but I still don't have 100% trust in the results so I keep my use of that tool to smaller assemblies where errors would be easier to spot.

cwilliamrose
08-30-2016, 07:33 AM
I gecha - Make the engine mount either out of lead or styrofoam depending on where the "as-built" CofG turns out.http://eaaforums.org/images/smilies/wink.gif

Or just change the length an inch or three.... ;)

Cory Puuri
08-30-2016, 02:17 PM
All better. Sorry. I didn't realize we had a limit on PMs as staff and that it was counting my outbox.

cwilliamrose
08-30-2016, 06:26 PM
Here's a link to the library we use over at the Biplane Forum;

http://79ft.net/pages/solidworks-models.html

(http://79ft.net/pages/solidworks-models.html) This is a list of the models available as of Aug 2014;

AN.Bolt.SLDPRT
AN310.Castle.Nut.SLDPRT
AN315.Plain.Airframe.Nut.SLDPRT
AN316.Jam.Nut.SLDPRT
AN365.Elastic.Stop.Nut.SLDPRT
AN381.MS24665.Cotter.Pin.sldprt
AN392.Clevis.Pin.SLDPRT
AN393.Clevis.Pin.SLDPRT
AN430.Rivet.SLDPRT
AN470.Rivet.SLDPRT
AN490.Rod.End.SLDPRT
AN665.Clevis.Terminal.SLDPRT
AN960.Washer.SLDPRT
AN970.Wood.Washer.SLDPRT
KP3.SLDPRT
KP3A.SLDPRT
KP3L.SLDPRT
KP4.SLDPRT
KP4A.SLDPRT
KSP3L.SLDPRT
MS20426AD.Rivet.SLDPRT
MS21042.Stop.Nut.SLDPRT
REP3H5.Assy.SLDASM
REP3H5.SLDPRT
REPB3N2.Assy.SLDASM
REPB3N2.SLDPRT
REP4F5.SLDASM
REP4F5.SLDPRT
REP4H6.SLDASM
REP4H6.SLDPRT


(http://79ft.net/pages/solidworks-models.html)

Jeffrey Meyer
08-30-2016, 11:13 PM
Here's a link to the library we use over at the Biplane Forum;

http://79ft.net/pages/solidworks-models.html
(http://79ft.net/pages/solidworks-models.html)
(http://79ft.net/pages/solidworks-models.html)

Outstanding stuff :)

skier
09-17-2016, 05:37 PM
I know this is nowhere near as complete as the Pitts, above, but it's a start. I'm new to Solidworks, but not 3d modeling. Right now, I'm just inputting a set of plans as drawn and will later go back and try to resolve any issues that don't solve themselves with more time and effort.

5794

Jeffrey Meyer
09-18-2016, 01:08 PM
Nice:)

How did you enter your airfoil and where did you get the data for it?

skier
09-18-2016, 03:31 PM
Nice:)

How did you enter your airfoil and where did you get the data for it?

I got the airfoil coordinates off the UIUC Airfoil Data site: http://m-selig.ae.illinois.edu/ads/coord_database.html#N

Then I opened the .dat file in excel and scaled it with the chord of the airplane. I saved that file back to a tab separated .txt file with a z-coordinate of 0.

I then followed the instructions on the site below for how to create a spline based on a .txt file:
https://grabcad.com/questions/tutorial-how-to-import-points-to-solidworks-from-a-text-file

Instead of scaling the file in Excel, there is also a scale option in solidworks under: Insert-->Features-->Scale. I found that after I'd already scaled it in Excel, but it is probably how I'd do it next time.

Mark Meredith
12-08-2016, 09:07 AM
All, I posted my Super Chipmunk model in a different thread and placed it on GrabCAD, but figured I'd put it here too. I've only been at this about 3 months - no prior experience with SolidWorks or any kind of CAD. I'm modeling my own airplane (which I rebuilt and modified so know it well) as a way to learn the software. Just learned about "render" and having fun with it.
Very impressive Pitts, CWILLIAMROSE! I have only learned how to do external lofting so far. Next goal is to turn my surfaces and solids into sheet metal then how to build structure underneath it. I haven't found much on this topic so far in my SolidWorks text or videos, beyond simple sheet metal design. I'm awed by what you have been able to model, Mr. Rose!592659275928

Mark Meredith
12-08-2016, 09:35 AM
Cory, is the Zenith available in an .SLDASM file that can be opened in SolidWorks? The eDrawing is interesting, but it's not obvious how to look at any part in detail to see how it was modeled or how the whole thing came together in an assembly tree. Thanks, Mark

Mark Meredith
12-08-2016, 10:11 AM
Skier, I downloaded an airfoil into notepad as a txt file then opened a new part in SolidWorks. "Curve Through Reference Point" is grayed out. I can't figure out how to bring it into SolidWorks using the tuturial...I'm missing some step. Any ideas on what to try?

cwilliamrose
12-08-2016, 10:36 AM
Thank you Mark,

Please call me Bill. I have admired your airplane since the first time I saw photos of it. It has style and it manages to distance itself from the stock airplane very nicely. I have flown stock Chipmunks a few times and they're a great flying airplane.

You have done the hard part in my experience. Using surfaces and lofting can get frustrating, at least for me. Parts in an aircraft structure are usually pretty simple to model but the assemblies can be difficult because SWx requires exact fits or the mates fail. After doing the model shown below I swore off surfacing but I bought a book on the subject so I guess I haven't totally thrown in the towel -- I have a cowling to design for the Pitts after all.

lathropdad
12-08-2016, 04:43 PM
I am scratch building a 4 place BearHawk. I have used Solidworks for decades in my work as a race car engineer and car designer.

Even though I have a complete set of plans for my project, I redraw most of the parts in SolidWorks as part of planning how I am going to build a part. Also by redrawing a part in SolidWorks, I can have any measurement I might want to check the accuracy of what I am building or use to build tooling to make the parts. I have found that I have a better understanding of what the designer of my plane had in mind as he drew the plans.

I also make use of DraftSight which is a 2D drafting program from the makers of SolidWorks. This package is a free download. It is an AutoCAD like program. This was especially helpful when I was laying out the wings. I was able to make some very simple drilling jigs that allowed me to hold tolerances of a few thousands of an inch over the length of the wings. It also saved days by not having to layout every rivet hole.

cwilliamrose
12-08-2016, 06:46 PM
I do my 2D work in SWx. To me DraftSight is next to worthless since the interface is ACAD-based.

Mark Meredith
12-09-2016, 06:51 AM
Thanks, Bill. I'm starting to work more and more with assemblies - the main landing gear and fairings are separate parts, and plan to do the tailwheel as a collection parts and assemblies. To make things fit well, is there benefit in building it as one part (well, all but the wheel) then splitting it into separate parts? I tried that out on the whole aircraft which came apart into 148 surfaces or solids! I'm thinking build some of the tailwheel parts that have to mate then split them. Good or bad idea?

cwilliamrose
12-09-2016, 08:52 AM
I admit to having tried making one large part and then separating it into smaller pieces. I didn't like it well enough to make it my normal method. One thing is that editing the sub-part becomes an issue because everything has to be changed at the base part level. That can lead to unintended changes to the sub-parts. I much prefer to use individual parts mated together in a real-world fashion. And I don't like taking geometry from one part to drive another part's geometry either for the same reason stated above. I will sometimes start out with features that came from a mating part but I will break those associations once the design is close to being finished because the InPlace mates required to maintain your converted sketch entities is not a real-world situation. So yes, if I change one part I may need to manually change some of the mating parts too but that's where using mates works in your favor -- the mates will protest if you miss a change to one of the mated parts, kind of like real parts do when they don't fit together.

I think many SWx users would call me crazy or a dinosaur but to me working in 3D has the most value when it simulates real parts and assemblies. Since I often have to build what I design I figure it's best to make my mistakes in SWx and get it right when it's time to make chips. I'm not saying the other methods are wrong, they just don't work for me.

BTW, the race car shown in a previous post was done in one piece and then cut into sections. That is one of the few times that method paid off for me.

Jeffrey Meyer
12-09-2016, 10:26 AM
Skier, I downloaded an airfoil into notepad as a txt file then opened a new part in SolidWorks. "Curve Through Reference Point" is grayed out. I can't figure out how to bring it into SolidWorks using the tuturial...I'm missing some step. Any ideas on what to try?

Hi Mark,

In a part window try Insert > Curve > Curve through XYZ Points...
You will be asked for a "Curve File", Browse for your Notepad text file and press enter.
Note that SW by default looks for a .dat file, not .txt - but when you browse for it you can change the browsing window to look for .txt file types.
Note also that the .txt file should be formatted in the form of a single line containing the delimited X,Y, & Z coordinates for each point (no headers or any other text).
The result will be a curve feature in the history tree (probably a good idea to rename the feature with the name of the airfoil).
In any sketch you can now Convert that feature into a black (fully constrained) sketch entity. By deleting the "conversion" constraint (thus making the entity unconstrained - blue) you can now do some cute manipulations. For example, in the sketch draw a straight construction line with a length equal to your required chord length and angled at your required angle of attack, and then drag the blue airfoil end points to the construction line end points. You now have your airfoil scaled and correctly oriented.

Hope this helps

AJLiberatore
12-09-2016, 01:09 PM
I am not looking to share this model but several of us do share common stuff -- AN hardware, etc and the link to the library is on the Biplane Forum website. Anyway, the image below is of a Pitts project I started many years ago and will finally be putting on the front burner. This model started out as simply the aileron control system and I was looking to modify the geometry to eliminate the differential travel. I'm using different ailerons so a lot of things changed and the goal for me was to evaluate what the travels would be with stock or near-stock components and then change the bellcrank angle to get identical travels up and down. The aileron system model progressed into also looking at my elevator trim system,,,, then a full fuselage (modeled as-built since it pre-dates Solidworks) with wings. I started this model in June 2013.

I'm working with an engineer on my aileron design and we communicate via email with Solidworks models. Makes life much easier for both of us!

I have been a Solidworks user since 1998 and I see this as a tool to confirm that all the parts will play together nicely. I hope to avoid building multiple versions of parts only to find out I didn't think of all the downstream effects of my changes. The scrap pile should be smaller and pixels are much cheaper than aircraft materials. Beyond that I design the jigs and fixtures used to make some of the parts and some of those have already been built.


5724

CW,

Your just the person I need to speak too. In my SW Class we just had a snappy introduction to the "Weldment" Module. With that in mind, I have a number of questions.

* Is that Pitts an "Assemby"?

Now onto the Fuselage, because what we have learned ( unless my teacher missed something ) is the following:

* Build your constrained wireframe ( Pitts Fuselage ) in the 3D Sketcher
* Go into the Weldment module, and draw / execute tube intersection points to get the proper fish-mouths of all tubes.
* Now from their, you have to create a model of each individual tube, save it so then it can be brought into an assembly when you are ready to do so.
* That is another and not linear step as compared to building a model(s) and bringing it into an assembly.

Is this a proper feedback? Or did my Teacher / Class miss something and the process is more like what we have learned up to know aka the model/assembly relationship?

BTW, he gave us a fictitious "Jeep Roll Cage" to do this with, I may post a snapshot later.

Tangent to this ( No pun intended ) are the longerons a spline? and how ( or ? ) are they constrained to keep them parametric?

I know this is a number of questions, however after my experience with the roll bar, I think of trying to do a simple fuselage like a Baby Ace or a Tailwind ( which might be a lot more work aka the longerons ) might be more work than a newbie might realize.

I look forward to your reply,
Anthony Liberatore

cwilliamrose
12-09-2016, 02:15 PM
Hello Anthony,

I'll take a stab at your questions;




* Is that Pitts an "Assemby"?

Yes, if you mean the entire airframe. Individual parts mated together with freedom of motion where that is important (like the control system).



Now onto the Fuselage, because what we have learned ( unless my teacher missed something ) is the following:

* Build your constrained wireframe ( Pitts Fuselage ) in the 3D Sketcher
* Go into the Weldment module, and draw / execute tube intersection points to get the proper fish-mouths of all tubes.
* Now from their, you have to create a model of each individual tube, save it so then it can be brought into an assembly when you are ready to do so.
* That is another and not linear step as compared to building a model(s) and bringing it into an assembly.

No, my fuselage is a wireframe with all the tubes still in place. I see no reason to take the individual tubes and re-assemble them -- they're already assembled. Did the teacher explain what benefit doing this extra work would have?

5935

This is the wireframe for my fuselage model.



Is this a proper feedback? Or did my Teacher / Class miss something and the process is more like what we have learned up to know aka the model/assembly relationship?

BTW, he gave us a fictitious "Jeep Roll Cage" to do this with, I may post a snapshot later.

All my extraneous stuff like fittings, tabs, etc are attached to the original weldment. Maybe there was supposed to be some learning of assemblies from this exercise but it doesn't add up to me. Maybe I'm dense and lazy, it's a strong possibility!

Here's a capture of my fuselage and the feature tree;

5936

Notice this is a part file and you can see the wireframe sketches that define the tube locations. This is part of the fuselage assembly which adds other parts like wing and tail fittings, fin, tailwheel mount, etc.



Tangent to this ( No pun intended ) are the longerons a spline? and how ( or ? ) are they constrained to keep them parametric?

No, the longerons are not bent in gentle curves like the roll cage was probably done. A proper truss needs to have its members straight from point to point. A curved tube will buckle easily when it is in compression.

Below is the fuselage part again with the 3D sketch for the longerons highlighted;

5937

That 3D sketch is used to create each longeron. You select the entities in that sketch to create each longeron which becomes a separate 'Structural Member' in the feature tree;

5938
Note the arrow pointing to 3D sketch and all the trims this tube is part of.




I know this is a number of questions, however after my experience with the roll bar, I think of trying to do a simple fuselage like a Baby Ace or a Tailwind ( which might be a lot more work aka the longerons ) might be more work than a newbie might realize.


I hope the above is helpful. The weldment part is fairly simple but of you go to the VR3 website (http://vr3.ca/refdocs.html) you can save some work by downloading all the tube profiles for aircraft tubing. I created many of my own before I discovered that resource.....Bill

Jeffrey Meyer
12-09-2016, 02:49 PM
.....
I think many SWx users would call me crazy or a dinosaur....


Bill, your approach is by no means crazy or antiquated - on the contrary, there is a much better description for it - KIS (Keep It Simple):thumbsup:

While splitting parts into multiple pieces does have some advantages - like the fact that a single change in the base geometry automatically updates all the other pieces and giving you that warm feeling of achievement in your tummy, the method has a couple of major disadvantages:
1. You will probably use each piece in the form of a configuration in the multi-piece part. Then, for each change you make the software rebuilds the whole part repeatedly for each configuration. With complicated parts (read "high feature count") this process can be very compute and memory intensive (read "much thumb-twiddling").
2. If the change causes even a small geometric topology change, subsequent features can fail and result in some frustrating efforts to remove all those annoying red error triangles in the history tree.

Frankly, I prefer to design each part as a separate model and get the warm tummy at the assembly level.

There is a fairly simple way of making a compromise between the two methods:
1. Make a part representing the base geometry, and then
2. Make each of the subsequent parts separately by opening a new part and inserting the base part as the first feature.

AJLiberatore
12-09-2016, 03:20 PM
Bill, Thanks.

Your Photos didn't come through in your response, or I am having a browser error. From what I can garner from your reply before seeing the photos is the Pitts Fuselage is wireframe with all tubes in place which would make it one giant "part" in the assembly, is that a correct read back? They tubes look like tubing so was the "Weldment module used, or did you Extrude-Cut to get each tube Dia / thickness and then use other Extrude-Cut to get the fish-mouths etc.?

My best,
Anthony

cwilliamrose
12-09-2016, 03:47 PM
Sorry about the images. For some reason you insert the images into the body of the message and they appear again at the bottom of the post. I deleted those 'extra' images and it seemed to be OK at work. Now that I'm home the images are gone. I have no idea what the problem is... I'll get the photos back into the message tomorrow.

Yes, the fuselage structure is one big part file with all the tubes as weldment features with the intersections trimmed/extended as needed. There's a cut list and all those tubes are separate bodies. If you make a change to the fuselage geometry by changing the wireframe everything updates as you would expect. I'm not sure what Jeffery is getting at, maybe I need to be at the CAD machine to make it sink in............Bill

Jeffrey Meyer
12-10-2016, 04:01 AM
I also couldn't see the images, and I'm not familiar with the Pitts fuselage structure. Can I assume that it's a fabric covered tubular structure where each piece of tubing is straight (unbent)? If so, can I assume that all the external fabric surfaces are either flat 4-sided polygons or triangular (flat by their nature)?

cwilliamrose
12-10-2016, 08:01 AM
I replaced the images, hopefully everyone can see them now.

The longerons are bent but only at weld clusters, in between clusters the tube is straight.

Formers and stringers added to the structure give the fuselage a shape that is not just a box. Those stringers also support the fabric so it doesn't drum due to having large areas that are not supported. I have not defined those completely yet, only enough to create the turtledeck's shape on the sides. The bottom stringers can be seen in post #7 of this thread.

cwilliamrose
12-10-2016, 08:40 AM
.....Frankly, I prefer to design each part as a separate model and get the warm tummy at the assembly level.........

The individual tubes are not created from drawings, they are fit into their locations by hand. I see no reason to make an assembly of all those tubes and suffer the resource hit the mates would require in building them into an assembly. If I change my wireframe dimensions the tubes are updated as to length and trim/extend features without red marks. There's definitely a disconnect here somewhere, I just don't see why you would want to work with anything but the original part file that contains all the tubes as weldment features. Making drawing of those tubes would be pretty much impossible anyway.

VR3 uses the tubes as individual models to machine the fishmouths on their CNC equipment. When you receive a kit from them the parts fit together like a jig saw puzzle. If you're building a fuselage from scratch you likely won't have access to the machinery VR3 has so models of the individual parts would have little or no value.

lathropdad
12-10-2016, 12:24 PM
Bill,

Have you used the simulation function to do a stress analysis of your fuselage? I made a change to my BearHawk 4 place and modeled that change to check my choices for tubing sizes.

I have done stress studies on tube structures I do for the race cars I build. And I have done torsion tests on the completed race cars. There is an excellent correlation between what I model and what I find in actual testing.

In another post, there is a description of how to make flat paper templates of the tubes in the cut list. it is a very useful capability/tool. Wish I had learned it years ago.

I looked doing a stress analysis for my fuselage as an educational exercise and quickly decided that I had no clue as how to model the loadings or what they would be like. I have only done the stress analysis on one part that had failed on another's builder's project and another part where the loads were very simple to know and calculate. The analysis I do on my race car frames is to develop a single number that I can then check on an assembled car and I use that number in calculating setups for the cars. By comparison a race car is a very simple system to analyze.

cwilliamrose
12-10-2016, 01:20 PM
No, I haven't played with simulation to see what I could learn for a few reasons. First, since the tubes are separate bodies I wouldn't think the tool would accept the fuselage structure -- I only have the light version available. And then there's the questions of what loads to apply. I'm not a structures guy so I would likely get answers to questions improperly asked. One more issue is the fittings attached to the fuselage where the loads should be applied, That would again require more than Simulation Light since you would be dealing with an assembly once the fittings became part of the structure.

SFahrner
12-10-2016, 03:40 PM
As a retired (?) aeronautical engineer/stress analyst guy who still does occasional consulting work using the SW/Simulation Advanced Professional package, I give a tip of my hat to cwilliamrose for his comment:

“And then there’s the question of what loads to apply. I'm not a structures guy so I would likely get answers to questions improperly asked.”

Many times in dealing with clients, the biggest problem in creating a useful FEA model is the lack of knowledge about the real loads (especially dynamic loads) to which the part/assembly will be subjected. It turns out that an analytical model that is “accurate” to within 5% isn’t very useful as a failure predicting tool if the applied loads aren’t known within a factor or 2 or 3…

Given that we are usually dealing with loads that aren’t well defined, I think the most useful application of the Simulation package in SolidWorks is for “Qualitative comparisons of design changes, rather than quantitative predictions of failure conditions”.

Dispensing with the analyst’s vocabulary, this means using the analysis tools to simply compare stresses for different shapes. For example, use the Simulation Tool to determine the stresses for a bracket with any convenient load (I often use 100lbs). Then modify the bracket (add a lightening hole, change a fillet radius, etc.) and compare the stresses in the “new” bracket to the original stresses. If the stresses are lower, you have likely improved the design…

The weight of the part(s) is available with a click on the “Mass Properties” button, so you can also readily compare the weights…

Also, regarding paper patterns for mitered tubes:
I still use the following elegant piece of shareware written years ago by Giles Puckett:

http://rorty.net/news/tube-miter-program-giles-puckett
(http://rorty.net/news/tube-miter-program-giles-puckett)
Even though I’m fairly fluent in SolidWorks, I find Mr. Puckett’s excellent program to be quicker for most of my applications…

Mark Meredith
12-10-2016, 07:32 PM
Hi Mark,

In a part window try Insert > Curve > Curve through XYZ Points...
You will be asked for a "Curve File", Browse for your Notepad text file and press enter.
Note that SW by default looks for a .dat file, not .txt - but when you browse for it you can change the browsing window to look for .txt file types.
Note also that the .txt file should be formatted in the form of a single line containing the delimited X,Y, & Z coordinates for each point (no headers or any other text).
The result will be a curve feature in the history tree (probably a good idea to rename the feature with the name of the airfoil).
In any sketch you can now Convert that feature into a black (fully constrained) sketch entity. By deleting the "conversion" constraint (thus making the entity unconstrained - blue) you can now do some cute manipulations. For example, in the sketch draw a straight construction line with a length equal to your required chord length and angled at your required angle of attack, and then drag the blue airfoil end points to the construction line end points. You now have your airfoil scaled and correctly oriented.

Hope this helps
Jeff,
That was easy! It took minutes to convert my airfoil, then set the chord and incidence. Way easier than what I did before on my Chipmunk, which was to import a sketch drawing, size it, set the angle, then draw a spline on it. Thanks! Mark

Mark Meredith
12-10-2016, 08:12 PM
Jeff, Bill,
As an experiment I tried the above using the airfoil (saved as a part file) brought into a new part file. Worked fine. I could build separate parts around the airfoil.

I also built a practice part from a textbook (a bench vice) with a base and multiple movable parts added to it. This method started with a top down assembly. Open a new assy, insert a new part (the base) and draw it. Then insert a second new part (the slide), using Offset Entities to set the relations between the parts (in this case, a .010 space around a slide). When finished it would not move. So I deleted the coincident mates and built new mates so the jaw could slide. That seems like a fairly good way to work...only real difference I see it that the top level is an assembly instead of a part.

I'll give this a whirl building my tailwheel as full tree of parts starting from the tailwheel assembly. Then will mate the assembly to the fuselage. Thanks!

Mark Meredith
12-10-2016, 08:16 PM
Sorry about the images. For some reason you insert the images into the body of the message and they appear again at the bottom of the post. I deleted those 'extra' images and it seemed to be OK at work. Now that I'm home the images are gone. I have no idea what the problem is... I'll get the photos back into the message tomorrow.

Bill, the images all showed upon my computer fine.

cwilliamrose
12-10-2016, 08:44 PM
Thanks Mark, I replaced them this morning and they seem to be OK now.

Mark Meredith
12-10-2016, 08:55 PM
VR3 uses the tubes as individual models to machine the fishmouths on their CNC equipment. When you receive a kit from them the parts fit together like a jig saw puzzle. If you're building a fuselage from scratch you likely won't have access to the machinery VR3 has so models of the individual parts would have little or no value.
Within the past couple of months there was an article in Experimenter in Sport Aviation, by Brian Carpenter. He described using SolidWorks to make the wireframe, then a method his company uses to print templates from SWx to cut the exact fishmouths. He described it as being quick and accurate. I could not find the article - maybe someone else has the link. Certainly seems to relate directly to this discussion.

lathropdad
12-11-2016, 11:11 AM
Mark;

I read the article and still had to get help.

When you do a weldment, SW generates a cut list. Go into that cut list and you will find all the tubes in the weldment. You then can export a single tube to a new drawing. You then have to cut very thin slot though one side of the tube. The last step is to convert the split tube to a sheet metal part and then you can flatten the part using the "flatten" function that is a part of SW sheet metal.

Hope this helps.

Mark Meredith
12-30-2016, 01:00 AM
All,
I modeled a complete Scott Tailwheel assembly down to every little part. It was fun but a crazy huge effort! I did it to learn about modeling a complex assembly in Solidworks, and think I achieved my goal even if I fried a few braincells and annoyed my wife. It's based on the original patent drawings, more recent drawings, photos, measurements of the Scott assembly on my Super Chipmunk, and the illustrated parts breakdown from Scott and various vendors. Now on to other things!
It's up on GrabCAD at https://grabcad.com/library/scott-aircraft-tailwheel-assy-1

5992

cwilliamrose
12-30-2016, 12:18 PM
Hi Mark,

Looks good in the screen shot. I tried to download it from GrabCAD but there's only the assembly file there, the part files aren't on GrabCAD so when you open the assembly the part files are not found which causes an error. In order to get all the parts and pieces it's best to use the 'Pack and Go' tool to create a ZIP file. You can then upload the ZIP file to the website.

Mark Meredith
12-30-2016, 07:15 PM
Bill,
Got it, thanks. Reloaded with the zip and a couple of images.

cwilliamrose
01-01-2017, 08:18 AM
The link to the new upload is https://grabcad.com/library/scott-3200-tailwheel-assembly-zip-1.

I took a quick look last night and the first thing I noticed was that most (all?) sketches are under defined. In my experience if you don't fully define your sketches interesting things can happen and none of them are good things. I try to always fully define my sketches at least in terms of the geometry in the sketch that actually creates the solid. It's best to fully define them all since it's easier to see if you missed something when one of the sketches is not fully defined (and has the "-" sign as a prefix). Things like splines are a PITA to fully define sometimes and I will resort to "fixed" constraints when all else fails. I do not recommend using "fixed" constraints for anything other than a temporary tool which gets removed later when better constraints are applied.

I'll look at the assembly in more detail later but I'd say as an early learning exercise you did a great job on a difficult to model object.

Jeffrey Meyer
01-02-2017, 06:53 AM
Pearls of wisdom:)

I would even go one step further and say that in addition to fully constrained sketches it's best to assign a material with known density to the part(s) so that further down the line you can extract the weight of the assembly. (In aviation weight is the name of the game). At the very beginning of creating the geometry I would even give some thought to the orientation in space and placement of the origin of each part. You can also make part templates with pre-assigned materials and other custom properties that you commonly use.

All nuances, but nice work Mark :thumbsup:

Mark Meredith
01-03-2017, 09:05 AM
...most (all?) sketches are under defined.

Bill, how do you do that? I recently went through some text material on repairing errors and external references (SDC’s Solidworks 2016 Advanced Techniques). Wish I had known these tools earlier because I’ve had lots of broken references as I’ve had to modify parts. (It got easier when I started using assemblies in the main gear/tailwheel so only had to repair mates). Anyway, much of this text treatment was about OVER defined drawings or bad external references, not UNDER defined. I picked a random drawing (sketch 4 of the Fork, part of the Tailwheel Assembly) that showed the (-) symbol. Much of the drawing lacked dimensions, so I added them. But the (-) remained. What am I missing?

Mark Meredith
01-03-2017, 09:16 AM
...At the very beginning of creating the geometry I would even give some thought to the orientation in space and placement of the origin of each part.

Jeff, thanks for the pearls (what’s that line about pearls before swine? :rollseyes:) I’m unclear about what I need to do differently regarding orientation and origins. For a circular part (lots of them in the tailwheel) I just placed the origin at the center of the circle, but placed it fairly randomly for more complex shaped parts. Can you give some more insight into orientation/origin considerations as I start a new drawing? Thanks!

Mark Meredith
01-03-2017, 09:39 AM
Does anyone have recommendations regarding textbooks? I've been through a couple of them from SDC on basic and advanced techniques, subscribe to Lynda for online SWx training materials, and have watched a bunch of Youtube videos. I much prefer the more organized training materials over the haphazard (but free) Youtube stuff. I found nothing in a Google search for additional advanced books (including texts on the soup to nuts design process using SWx). I did download one on Finite Element Modeling that has some material about the design process including stress analysis. I just started reading it; it looks worthwhile but your comments above tell me I'm missing some key modeling skills.

By the way, here's my main gear. It was much easier than the tailwheel but not as complete (nothing internal to the strut, no brakes, etc). But it moves which is cool. Clearly it also suffers from under-defined drawings. 6001.

cwilliamrose
01-03-2017, 10:14 AM
The biggest issue with Sketch4 is the splines which are a PITA to fully define. I'd use tangent arcs instead if that were possible for this part and it would also make it easier to machine.

6004
First, I changed to ANSI dimensions because ISO drives me crazy. :rollseyes:

I added a colinear constraint to the vertical lines at the end of the fork and symmetrical constraints to some other points and lines. Then I added some dimensions to the lines and points to make them turn black. Finally I dimensioned the splines. This requires angle and distance dimensions at each spline point. Or you can fix them but I didn't do that here. The 179.95° angle on the outside spline could have easily been a tangent constraint instead.

For a part like this you can model half of it and then mirror the other half using the Mirror Feature tool which makes the parent sketch a little easier to deal with. Or you can mirror the sketch entities but that's not usually ideal due to the clutter you add to the sketch.

Mark Meredith
01-03-2017, 12:17 PM
Thanks for taking the time to do that, Bill! Very helpful. In the Youtube videos I've watched the instructors always dimension the arcs but I didn't know why. I've used the mirror more and more (and dynamic mirror which is nice), but usually mirroring the sketch not the solid model. I'll work on that. I'll pay attention to turning lines black also. What kind of bad stuff can result from an under-defined drawing?

cwilliamrose
01-03-2017, 01:16 PM
Anything in a sketch that is not fully defined can move. I have never understood all the mechanisms that allow this to happen within a part or assembly but I have been the victim of it more than a few times which is why black is one of my favorite colors. These days I pretty much only see it when I'm working on another person's models where I'll edit something and a seemingly unrelated feature goes crazy because the sketch that feature was based on changed. I try very hard to thoroughly check for fully defined sketches in a model I didn't create before I change it -- and I only work on a copy of the original in case kablamo!! occurs.

I also like to get rid of any 'InPlace" mates which I consider to be time bombs when you're making changes to an assembly. By 'changes' I mean editing a feature or sketch as opposed to adding a feature to modify another feature when a simple edit should give the same result -- something I consider to be very poor technique. People who do this are often conditioned to do so by past experience where models have blown up (collapsed, turned red, etc) due to being a house of cards full of under defined sketches, lots of external references, etc. If you don't touch the existing features the model will usually remain whole but you end up with a feature tree a mile long that is impossible to deal with. The other group of people who do this are coming from a non-parametic CAD program where this is the only way to edit a model.

There are many ways to create a model and several of them can be considered 'correct', the rest not so much. My methods are mostly the result of experience and liking my models to behave like real parts.

Mark Meredith
01-03-2017, 02:01 PM
Bill, okay, got it. I went to the next sketch in the Fork and fully defined it. Man, a LOT of dimensioning. That may cause me to sketch in a different way with fewer/simpler curves (already figured that out anyway - can't make a smooth part with lots of curve points).

But all this dimensioning also means it's hard to make fine changes. No going in and just grabbing something to adjust, then close the drawing. I've done plenty of that. Gotta change the dimension instead of dragging the point. Or delete dimensions, drag, then put them back. I see the wisdom of this discipline though.

My Chipmunk model is a mess of interrelationships (many external refs) that would require major rebuilding to modify anything. For example I know the wing incidence is a little off. Even though it will be used by Horizon Hobby to make a flying model, I ain't gonna fix it. I already rebuilt it once to change the airfoil a little and it was a disaster - started over instead of fixing. Guess this is what you mean by blowing up! And of course building assemblies would have been much better too. I wonder if Horizon is even going to be able to use this thing. They may pull out a drawing or two, reference a few curves and start over with their own 3D model.

cwilliamrose
01-03-2017, 02:46 PM
It's a different world when you're trying to re-create an existing part. You would likely not use splines to define your geometry in a new design. If it had to be shaped like your fork you could use arcs instead;

6006
Still lots of dimensions but a bit more straight forward than dimensioning splines. As you can see, this sketch closely follows the shape of your fork without using splines. A simpler design with less arcs and a straight line or two would look almost as nice and be much more producible.

Remember to use the 'Equal' constraint for line lengths, radii, etc. Makes for a less cluttered and easier to modify sketch. I only used one 'Equal' dimension here -- the R.43 is equal to the arc's radius in the upper left corner of the sketch which is why that one isn't dimensioned.

Mark Meredith
01-03-2017, 03:48 PM
Yes, I see that is much simpler. And no need to fight to find the problem when a spline won't go black.

Did you set the arc joins to be tangent?

Okay, what if all the drawings in a part are fully defined but the part still shows (-)?

cwilliamrose
01-03-2017, 04:25 PM
Yes, the arcs in my sketch are all tangent which allows me to fully define them with only one location dimension.

>>Okay, what if all the drawings in a part are fully defined but the part still shows (-)? <<

I assume you mean in the context of an assembly? If the part file or sub-assembly has a "-" that means it's not fully constrained within the assembly and it has at least some freedom of motion. Sometimes you don't really need or want to fully constrain a part but most times you do. If you have a bolt you constrain the shank to be concentric to the bore and the base of the head to be coincident to the surface the head draws up to but you don't really need to constrain it in rotation. If your fork is free to rotate you can move it and all the parts attached to it in rotation (steering) if that has value to you. If not you'll want to fix the rotation so it doesn't just move because you grabbed it with the mouse or Spaceball by accident.

Jeffrey Meyer
01-04-2017, 04:00 PM
Hey guys, I like/love using fully defined "black" splines. Here's an example:

6007

I like splines for two reasons:

1. They are aesthetically pleasing.
2. They can be constrained to have curvature continuity, unlike circular arcs that can only be constrained to have tangency continuity.

In a way these two characteristics are linked together by nature. There is only one thing in nature that is (almost) perfectly round - your eyeball/lens. Apart from the stalks of some plants practically all other curved objects in nature have curvature continuity - that's what makes them aesthetically pleasing.
This is true in engineering as well - you do not want to have your airfoil made up of a series of tangential circular arcs - it will be inefficient and have terrible stall characteristics.

Incidentally, the tail-wheel fork (spline version) shown would be somewhat lighter because it has strength where needed and less material elsewhere. (IMHO it looks nicer too!)

cwilliamrose
01-04-2017, 04:48 PM
Tell me about the blue vectors, are they subject to change because they are not fully defined?

There are places where only splines will do and airfoils is a good example. I still use arcs as a first choice for most things because I can create the part with simple tools and a drawing. Wood ribs have splines for their shape but the wood isn't fully supported along its length if it's a stick rib so the accuracy is not going to be great in the finished part. If it's fabric covered there are a whole list of other deviations that happen. Still, you have to start somewhere.

The tangent arc version of the fork I drew would be indistinguishable from one defined by splines unless you could measure it very closely. Visually there would be no difference.

Mark Meredith
01-04-2017, 09:20 PM
Arcs and simple tools: Bill, do you know an example of where an arc would be easier? Most of my aircraft part making has been sheet metal shaping, forming with hammers and wheels, and fiberglass/molds. A lot of stuff with big rolling/sanding motions that do complex curves nicely. I did a little aluminum work using a metal lathe for the Chipmunk - in that case only an "arc" was possible of course. As I think about a clean sheet design I'm very interested in materials and structures, and how to make them!

cwilliamrose
01-05-2017, 07:53 AM
Mark,

When I do metal shaping I usually don't have much of a drawing, just some basic targets to hit. The inner panel here is hand formed to fit over the brake caliper, fit the existing mount bracket and the pant. No drawing at all, just keep making the bump bigger until it clears the caliper and then smooth it out;

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6010

For something like the turtle deck on the Pitts I have drawings for the bulkheads which I can use to make the form blocks. If I made the curve a spline I would have to make the drawing full size, go the the print shop and have it printed on bond paper, glue the drawing to poster board, cut it out and use that as a template for the wood block. As a curve made up of arcs I can lay it out directly on the wood referencing a small drawing I can print myself and start cutting;

6011

6012

The front bulkhead is reclined and was done by drawing an intersection curve on an angled plane. That bulkhead is described by splines but I'll use arcs to make the drawing so I don't have to do the print shop routine.

Mark Meredith
01-05-2017, 09:15 PM
Bill,
Okay, your turtledeck example makes it clear why curves instead of splines. Thanks!

Some BS (Before SolidWorks): I avoided the problem of having to draw much of anything on my Chipmunk because I had no detailed airframe drawings. All the metal forming was with paper templates and lots of fitting until it looked right, kinda like in your pics (very nice forming, Bill!) On the turtledeck I figured out the fore and aft widths to get the curved height I needed to cover my head and join with the fin (trial and error mostly), using the full 8' length of my sheet. I only made forward and aft bulkheads, nothing in the middle to deform the shape, and made those AFTER the turtledeck was mounted via stressed skin to naturally hold a smooth curve. Cut the turtledeck sheet out, bent the flanges where they rivet to the fuselage on an 8' brake, and drilled the rivet holes in the flanges. Snapped lines on the fuselage then drilled and clecoed one side so the sheet pointed straight up. Then bent it down to the opposite snap line using battons and friends...drilled and clecoed...riveted...done. Everything here and elsewhere was trial and error with lots of scrap, wood, cardboard, etc. I'm looking forward to trying to design with SWx instead of "that looks about right" directly on the airplane! 60176018

cwilliamrose
01-06-2017, 08:13 AM
There are times when doing it on the airplane works best but SWx gives you options you never had before so I try to use that tool when I can.

6019
This confusing view shows my layout for the T-deck and how the upper side stringer needs to be made to give me a positive break angle for the fabric coming off the bottom of the T-deck. This was an iterative process that defined the bulkhead shapes as I was paying attention to where the top stringer would have to be to make the fabric look right. The lines you see on the T-deck skin are intersection curves created from an array of planes that cut through the T-deck. The construction lines are tangent to those intersection curves and extend down past the top stringer. The highlighted green line is a curve defined by the points of intersection between the construction lines and the plane of the stringer. In order for the fabric to have a positive break angle at the bottom of the T-deck my stringer has to be inside of that green line. I'll offset that line some distance inboard as a first shot at defining the stringer's curve.

Before I did this layout and made the needed changes to the bulkhead shapes my T-deck would not have had a break angle at the bottom and the fabric would have come out of contact with the T-deck skin before it got to the bottom. I have seen airplanes with this problem and it is ugly. In the air the fabric sucks in due to the interior of the fuselage being a low pressure area but on the ground the fabric would not neatly flow off the skin to the stringer. Trying to glue the fabric to the T-deck to force contact makes things look even worse. You could do this on the airplane but using SWx makes the process much quicker since you don't have to make multiple versions of temporary parts to define this area.

Thanks for the kind words about my little panel. That was supposed to be a practice panel so I made it out of a piece of a jon boat seat we had in the scrap pile. Turned out to be a keeper which probably shows that taking the pressure off by calling it a practice part has some real benefits........Bill

Jeffrey Meyer
01-06-2017, 10:17 AM
Tell me about the blue vectors, are they subject to change because they are not fully defined?

6022

You have full control of the tangent weighting and direction (the blue vectors), so you can "blacken" everything on the spline. It's usually not necessary to define the weighting because the most aesthetic shapes of splines are usually "relaxed" - aka "minimum energy splines".

cwilliamrose
01-06-2017, 11:10 AM
So you're saying the weighting doesn't tend to change on its own? No need to nail it down? I'm clumsy enough to change it by accident. :D

Mark Meredith
01-07-2017, 12:17 PM
[QUOTE=Jeffrey Meyer;... .[/QUOTE]

Jeff, can you elaborate on "relaxed," "minimum energy splines"? Unclear what it means.

What if you want a spline to change? I was trying to recreate an elliptical wing discussed in another thread, modeled using a surface sweep, much to my surprise. It used only the root airfoil, LE and TE. Mine would not proportionally"shrink" the root rib height toward the tip rib, only the chord. I tried adding more splines to define a spar shape (worse) then defined the root airfoil lines and handles to turn them black (worse still). Thanks! Mark
6023

Jeffrey Meyer
01-08-2017, 07:50 AM
Jeff, can you elaborate on "relaxed," "minimum energy splines"? Unclear what it means.

Mark, permit me to digress a little here with a short explanation of what splines are:
Splines were invented/used hundreds of years before computers were invented and the only software that was around were woolen socks. However, engineers in the shipbuilding industry did use CAD systems - CAD stands for "Craftsman Assisted Design". i.e. The big-deal engineer designed the ship, and then when things didn't work out right he blamed the craftsman and made him (the craftsman) fix the engineering screwups.
Seriously though, splines were made of long thin strips of wood lain on the floor of the "loft hall" where the craftsmen drew bulkheads, profiles, plating, and other curves on the floor, at 1:1 scale, by tracing along the splines of wood held in place with weights known as "knots". The coordinates of the knot positions were given in tables known as "offset tables". You can recreate such an offset table directly from the spline node coordinates, and then recreate the actual spline on your table/floor using the ancient but well proven spline technique used by our ancestors.
By their physical nature such splines would adopt a "minimum energy" shape. For example if you tried to bend the spline to pass through 3 non-linear given points, the bending moment at the middle point would be at a maximum while the bending moments at the ends would be zero. the final result would be some finite minimum radius of curvature at the middle knot and infinite (straight line) radius of curvature at the end knots. Clearly this is completely unlike a circular arc that is uniquely defined by 3 points in space - i.e. there is only one circular arc that can pass through 3 pre-defined points, while there are an infinite number of splines that can pass though those same points. So, we need some extra constraints to uniquely define the spline. Enter tangent directions, tangent weighting, and radius of curvature at the nodes/knots. SW "simulates" the minimum energy of those bent sticks using NURBS - Non-Uniform Rational Basis Splines - they call it "Relax Spline".
Here are some links that explain everything much better than I:

Lofting
https://en.wikipedia.org/wiki/Lofting

Splines
https://www.izenda.com/blog/from-ships-to-data-a-history-of-the-spline/

NURBS
https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline





What if you want a spline to change?

Being a good Jewish boy, I'm going to answer your question with another question:
What do you want to change in your spline?
If you want to change the tangent direction/angle of the the spline at any particular node/knot, then you can do that by making the tangent blue arrow at that node parallel to a sketch line (2D or 3D).
If you want to change the "power" of that tangency you can do so by dragging it or defining it numerically.
You can also define/change the radius of curvature at the spline end points.

BTW - a small tip on designing with splines: Use as few nodes as possible. You would be absolutely amazed at the variety of graceful splines you can generate using only 2 nodes and defining their end-point tangents.


I was trying to recreate an elliptical wing discussed in another thread, modeled using a surface sweep, much to my surprise. It used only the root airfoil, LE and TE. Mine would not proportionally"shrink" the root rib height toward the tip rib, only the chord. I tried adding more splines to define a spar shape (worse) then defined the root airfoil lines and handles to turn them black (worse still).

I'll get back to you on this one ...


Thanks! Mark

Don't mention it;)

Mark Meredith
01-09-2017, 08:07 AM
Jeff, thanks for the links! Mark

Jeffrey Meyer
01-10-2017, 11:45 AM
I was trying to recreate an elliptical wing discussed in another thread, modeled using a surface sweep, much to my surprise. It used only the root airfoil, LE and TE. Mine would not proportionally"shrink" the root rib height toward the tip rib, only the chord. I tried adding more splines to define a spar shape (worse) then defined the root airfoil lines and handles to turn them black (worse still).

Mark, I threatened to get back to you on this so here it is:
6046
6047
6048

This is a solid loft using the root airfoil as the start profile, a point as the tip profile, and the elliptic leading and trailing edges as guide curves.
I couldn't post the SW part file because it's too big (200Kb), but I can send it to you (or anybody else) by mail (or any other way you like) together with a detailed explanation on how I did it. I don"t want to post the explanation here because I get carried away with my long explanations.

Mark Meredith
01-11-2017, 07:59 AM
Thanks, Jeff. Could you post it on GrabCad with the EAA tag?
I tried building this and it worked with the LE guide curve. But I drew the airfoil with a squared off trailing edge because I've seen and read that SWx does not like shapes that come to a sharp point. This means of course the TE guide curve did not work because the airfoil can't come to a point at the tip. How can this be built using a sweep that ends short of the single point tip, keeping the square TE?

Mark Meredith
01-11-2017, 07:20 PM
Jeff, thanks for posting it GrabCAD. Interesting how you built the airfoil. How did you get from the text files to the airfoil drawing? I'm also curious about the extra leading edge points. I thought it was to improve the LE accuracy on the drawing but they show up on the center construction line instead. Thanks, Mark

Jeffrey Meyer
01-12-2017, 04:47 AM
Jeff, thanks for posting it GrabCAD. Interesting how you built the airfoil. How did you get from the text files to the airfoil drawing? I'm also curious about the extra leading edge points. I thought it was to improve the LE accuracy on the drawing but they show up on the center construction line instead. Thanks, Mark

Mark, together with your previous post there are several issues here:
1. Text files to drawing,
2. Extra airfoil points,
3. Squared off trailing edge.

I'll try to answer each in separate posts.

1. Each .txt file contains a list of X,Y, & Z coordinates of the airfoil. The upper and lower airfoil curves are in separate .txt files.
To read them into SW, go to Insert>Curve>Curve through XYZ Points.
In the Curve File dialog box choose Browse, and then in the explorer window on the right of the File Name box, choose file type Text File (.txt). Then pick one of your airfoil .txt files. Repeat for the other airfoil .txt file(s).
You now have the airfoil curves in your SW part - you can Convert each curve into any sketch, make it "blue" by deleting the "conversion" constraint, and orient/scale/manipulate the resulting blue spline any way you like, simply by dragging it with your mouse.

Hope this answers your first question.
More to follow.

Mark Meredith
01-12-2017, 03:03 PM
Ok, got it Jeff, thanks. Successfully pulled in points, converted and scaled them.

supik
01-09-2019, 05:24 PM
Fresh Air Nozzle:

7636

https://grabcad.com/library/aero-vent-1

rwanttaja
01-11-2019, 08:45 PM
RAF Mk II Reflecting Gunsight:
http://www.bowersflybaby.com/sight_image.jpg

A lot of noob mistakes in the design, but it turned out pretty good. It's sitting atop a WWII A-10A aircraft sextant.

Note that it kinda "works". The reticle on the horizontal section is reflected in the angled plexiglass on top. Sure, it doesn't have infinity focus, and I can't adjust the sights for Pietenpols or RV-3s, but heck....

It needs a base to sit atop a curved panel, and I may replace the printed reticle with slits and electroluminescent panels or LEDs.

At my EAA meeting last night, I mentioned downloading Solidworks as a free EAA member benefit. One guy was shocked. He just bought a copy for work, and it cost almost $10,000.

Nice benefit, folks.....

Ron Wanttaja

Eli Josephs
08-06-2019, 11:16 PM
Some of you may enjoy this! For the past few years I've been working on various B-17 restorations across the country, and have been working on building up my own airworthy cockpit section. Some day, I hope to recover a wreck or project, and get it to an airworthy status... But that's a long way off! For now, I've been making the most complete and accurate CAD model of the B-17. Specifically, this is B-17G-80-BO 43-38083.

I started using a different educational copy of Solidworks. Since then, I have become a certified Solidworks Associate, and then a certified Solidworks Professional through the CSWA and CSWP.

Here are a few older renders of my work:

7980
7981
7982
7983

cwilliamrose
08-07-2019, 11:02 AM
Fabulous work! I can appreciate the effort involved,,, well, except for the rendering. I don't do renderings. :eek:

I have some experience with B-17 parts but it was in my pre-CAD days. I made the aft skins for the somewhat inaccurate stringer tail on the Collings B-17G-80-DL. It least they're aluminum and not fiberglass!

I hope you continue to post regarding your progress, very cool stuff.

Cory Puuri
08-13-2019, 03:01 PM
Some of you may enjoy this! For the past few years I've been working on various B-17 restorations across the country, and have been working on building up my own airworthy cockpit section. Some day, I hope to recover a wreck or project, and get it to an airworthy status... But that's a long way off! For now, I've been making the most complete and accurate CAD model of the B-17. Specifically, this is B-17G-80-BO 43-38083.
I started using a different educational copy of Solidworks. Since then, I have become a certified Solidworks Associate, and then a certified Solidworks Professional through the CSWA and CSWP.


Beautiful work! At AirVenture, I was talking with a volunteer who has worked on EAA's B17. EAA subscribes to Aircorp's Library (http://aircorpslibrary.com) (a steal at $5/month) and this volunteer has worked on creating various schematics and notes for our maintenance team from scans of the B17 manuals in the Aircorp Library. We were talking about how it would be great if we could enlist EAA Volunteers to redraw warbirds (and other aircraft) in SOLIDWORKS to assist others in restoration work.

rmlewisjr
08-21-2019, 11:20 AM
Cessna R182 Trim wheel light cover. One of my first attempts.

Cory Puuri
08-26-2019, 01:35 PM
Cessna R182 Trim wheel light cover. One of my first attempts.

Nice looking file. I learned something new, too. Windows 10 has a built in STL file viewer! Mind if I upload it to GrabCad and link to it?

2ndsegment
04-03-2020, 12:09 PM
I have models I build in Carrara and send through NETFABB as exported .3ds and then out of NETFABB as .stl . I then can import to Solidworks 2013 which cannot export as .stl only as several .STP s or a Solid part or assembly. So with all the danger to me involved, I give you https://grabcad.com/dalestoner-1/models?page=3

Drake Firebreed
06-29-2020, 08:11 PM
So I'm not as talented as most the designs I see on here but I have fun creating basically wind tunnel models and test them in flow sim. I figured I'd share some of my new ones (hopefully this is the right spot). Mainly working on lifting body high mach and boost glide designs but figured I'd try my hand at a reverse wing as I love the look. It's fist attempt so not exactly where I would like it but I learned some stuff.

Working on a new design. Took inspiration off the U-2 and Reaper. About 5700lbf on the wings. 30 x 54ft. CG is pretty good. Wanted to design a push prop. I call it DB-1 Already gonna be working on 2 Someone suggested a ducted fan. Calculated it at about 330fts.

rmlewisjr
09-13-2020, 05:18 PM
Nice looking file. I learned something new, too. Windows 10 has a built in STL file viewer! Mind if I upload it to GrabCad and link to it?
Not at all, go right ahead.