How to split a lofted body with another loft

[tmcnam]

Hi All,

Neophyte Fusion 360 user here. I am trying to make a rudder half mold from a lofted vertical stabilizer for my Formula One airplane. I need to cut out the rudder from the lofted body but keep the hinge centerline along the entire length of the rudder. I have pulled my hair out trying to figure this out. I have tried lofting the rudder alone with it's rounded leading edge but keep getting strange shapes even though the preview looks good. I'm sure I'm giving a terrible description but perhaps someone can point me in the right direction. I can usually eventually figure this stuff out using search etc. so this is my first post. I hope it's not too convoluted.

Thanks in advance for your valuable time.

Best regards,

Tim McNamara MD

[Beyondforce]

Hi @tmcnam,

Did you use a plugin to create of the airfoil shape?

Cheers / Ben.

[Beyondforce]

You should recreate the model, but this time, Don't forget R.U.L.E #1! 1 Component for the Tail and a 2nd Component for the Rudder. Use the Spline to create the airfoil.

The sketches that you have now, are made of multi lines connected to each other. Which I believe, is the reason the Loft command is having some trouble with!

Last thing, it is a good practice to to sketch in the center of the coordinates!

Let me know if you need more help.

Cheers / Ben
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[tmcnam]

Hi Ben,

Thank you so much for your reply. The airfoils are slightly modified through a standard airfoil design program and outputted via .dxf conversion. I have no way of creating an accurate airfoil using splines (I don't think). Is there any way to convert a multi-line to a spline automatically. I will try to use spline and select each point that makes up the multiline.

I use the origin for the nose coordinate of the base airfoil since that is what all other measurements are referenced. Since the whole vertical stab is lofted using a spline for the top as a rail, I'm uncertain how to loft the rudder alone with regard to the tip and still have it match the Vertical stab (which is why they are not separete at this time).

Thank you for help. It is much appreciated.

Best regards,

Tim Mc

[Beyondforce]

You should try this plugin:
https://apps.autodesk.com/FUSION/en/Detail/Index?id=1569210467479959341&appLang=en&os=Win64

[Beyondforce]

This site will have you with the Airfoil type:
http://airfoiltools.com/airfoil/details?airfoil=naca0018-il

[tmcnam]

Thank you for the reply.

The airfoil is a 6 series airfoil, specifically a 65A (0.0) 09  a=0.8 so I can't use the generator.

I have the coordinates for the airfoil and in fact use an Airfoil design program. This one is not modified much but my wing airfoils are, so I can't always use stock generated airfoils from websites.

I tried redrawing with splines and even using 20 or so fit points the drawing was off by a little over 6 thou (+.006). This is unacceptable accuracy for what I need so I would like to continue to import my DXF (or other file type) generated by my other design programs.

I've seen where others have had problems with lofting particularly when using airfoils with a high number of fit points. I have also had trouble modeling my steel tube fuselage for modifications using Fusion 360 since there still isn't a good tubing feature (as on SolidWorks)...sigh.  I've invested several months learning this software so I hate to start over and have to learn SolidWorks but I feel like I've wasted a lot of time trying to do what seem like simple tasks in other CAD programs. I'm sure it's just my own inadequacies but perhaps this isn't the best software for this type of work. Since I don't know what I don't know I'm uncertain if I should continue to use my time trying to learn this software.

Thank you again for your generous help.

Best regards,

Tim

[Beyondforce]

Fusion 360 is perfect for this. You just need to figure out a way to create the airfoil. There must be another way to create this airfoil!

In regards to the fuselage, you can use the T-Spline for that. If you need help just let me know.

[Beyondforce]

@tmcnam,

Please check the attached file. Is that what you needed?

Ben.

[Beyondforce]

@tmcnam,

Okay, in the screencast I'll show one technique (there are few more) on how to create the Tail and the Rudder, from your DXF file.

I'm also mentioning the fact that you forgot to follow R.U.L.E #1, this is very important! If are you not gonna follow R.U.L.E #1, you will have a lot of problems a long the way.

If you have any question, please let me know.

Cheers / Ben
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[davebYYPCU · Accepted solution]

Gooday Tim,

I added a few steps to your file,

Airfoil looks OK to me, but I use splines to avoid the imported body edges - later you will have to check if the bodies are indeed faceted straight panels

Ben"s revommendation for Rule 1, won't argue there, however you had done the loft, and Ben"s example was for the preliminaries anyway,

all you needed were the extrude - combine operations,

You did not detail how the hinge curve was to be produced in the tip area, so I sort of extended the tapering cylinder, and took what we got, refining from here is all yours

I created a cutting block of material to remove the Fin, to leave you with just the rudder, straight cut, no drama,

Then I created the mold block of material, used the rudder to cut the negative in the mold.  That is where it is up to now.

Yes there maybe some house keeping to do, the right side of the rudder, and sketch 2 were corrupted, as received, so mirror the new mould for the other side.

You will see how it is done by rolling back the timeline, taking a step at a time, at each Step, use Edit Feature to follow the selections.

You will also have to save out the model of the fin, early in the timeline, if you need it, or make your mold for it the same way.

Too late in the evening here for Rule 2 and 3.

Should get you going again, will do a screencast tomorrow if required, let me know.

Edited file attached.

You will find the Combine tool handy for the steel tube framing as well. 

Browny

[tmcnam]

Hi Dave and Ben,

Again thank you both so much for your time and efforts. They are much appreciated.

I only have time to quickly look at the screencast that Ben put up. After work today I'll look at both carefully. I did learn some new techniques already with that screencast regarding Patch and Stitch commands, thank you for that!

Ben, That looks very nice and is close to what I'm going for. One of the reasons I never got to rule #1 is I couldn't figure out how to even start. For proper rudder authority, I need the rudder to extend full length to the tip. You'll notice by lofting the tip separately there is a noticeable break line there. I lofted the complete Vertical Stabilizer and rudder together to eliminate that break and make it look as if it was one piece and the start of the tip is tangent to the main body. Then I was going to "extract" the rudder from that but never figured out where to start. The hinge line has to remain straight and ideally the rudder leading edge curve would taper in accordance with the lofted taper of the complete assembly. I hope that makes sense. 

Dave, I look forward to studying yours carefully as well, as the rudder does extend to the tip and down below the stabilizer and it sounds as if you may have done that. 

I'm amazed at the talent here on this forum. It takes a certain way of thinking and planning to do some of these more complex operations and watching Ben's screencast was very enjoyable. It may come easy to you guys but to newbies it is still amazing to watch and learn these techniques.

Thanks again to you both.

Best regards,

Tim McNamara MD

[davebYYPCU]

Gooday Tim, 

I only worked with your file as it was when you posted it, but extending lower, will just change a bit of what both of us suggested.

Join another Loft to the base rudder profile, wherever that works out to the current rudder, then edit my mold to cover it.  Won't be that simple but you get what I mean.

As said, you have a bit to go, design and dimensions, are for you to complete.

As neither of us are in your part of the world, you may find the time zones need to be accommodated, 

I was new to Fusion, received a deal of help, now I'm happy to help with what I can. I am using Fusion for RC Aviation, just a tad smaller than your project.

Browny.

[tmcnam]

Hi Ben and Browny,

Well, I couldn't wait until this afternoon so I came home for lunch to look carefully at bot models and the screen cast again.

There are not enough thank yous I can give for you both. I tend to try different things for weeks and search the forums etc and can usually figure out what I need. This was my first time to use the forum for a question and I could have saved myself weeks had I asked for help earlier. Live and learn.

Ben, your model was very close but I hadn't given you all the information you needed such as the rudder extending all the way to the top. Also the split body looks as if it used the bottom aileron leading edge curve and I need a constant taper (but keeping the hinge line vertical. I picked up about 20 tips via your screen cast. I'm still a little hazy as to when Patch is better to use than modeling but I'll get there. Those screen casts are invaluable. Thank you again.

Browny, Your model was exactly what I needed. I have trouble using the parametric history to tell exactly what you did (screen casts are of course easier for the neophyte) but after looking at the steps I had an epiphany about how to do it based on what you had done. I think I can use the projected surface in the plane at the hinge line and loft between that and the trailing edge using the bottom aileron rib and the tip as guide rails. Still, if you have time to do a screencast, that would be fantastic just to see exactly how you did it. If you don't have time it is ok as well. You two have given me exactly what I need! Man, I'm fired up about Fusion 360 again! Can't wait to get on the CNC Router and cut some molds so I can begin laying up the carbon fiber!

Many, many thanks to you both.

Best regards,

Tim McNamara MD

[Beyondforce]

@tmcnam,

If you have a picture of the real thing, that would be a huge help. There are many types of Rudders out there (I should know, I'm a Pilot ;)). Beside that, you should build all parts In-place and not on separate files.

Are you building this model after a specific airplan model?

Ben.

[davebYYPCU]

Just to be complete, can you let me know the length of the hinge line, I will extend the rudder in the screencast, with that info.

 Aileron rib?

Unless I am off base, I will/would scale the existing base rib, on a plane at the base of the rudder.  

However I realise that it could be different, presuming it will match the line of the fusealage.

[tmcnam]

Hi Ben and Browny,

Here is a pdf 3-view of the plane. I using the tail as per plans except instead of wood it is vacuum bagged carbon fiber with Divinycell foam (PVC foam) cores. The rest of the plane is a modification of my current race plane which is a Cassutt (picture is right after I qualified at Reno Air Races this year). I've got a new wing and fuselage shells for it and of course it'll have the new tail.

The other Fusion drawing is what I use to measure angles etc. for the tail and tail spar. It's my scratch pad to mock up cloth thicknesses and so on. Browny, it has the spar in it which will be c-section with opening towards the rear (it's modeled solid now as it will become  right and left mold halves. It does taper with the fuselage.

If I didn't have to work for a living to pay for my toys I would have already attempted to finish drawing and get it to my shop in the CNC Router. 🙂

Best regards,

Tim Mc

[tmcnam]

Hi Browny,

Please see above post.

Thanks again and best regards.

Tim Mc

[davebYYPCU · Accepted solution]

Gooday Tim,

Looks more like my Nemisis, than a Cassutt 111, Wow from Reno, it's on the bucket list, but not likely.

I did the screencast, and sent link via PM, as I have not kept it to forum level,

I didn't see the hinge post drawing till just now, but whats done is easy to modify, based on the later drawing,

Love your enthusiasm.

Browny

[Beyondforce]

Hi @tmcnam,

The attached info is great. This is my recommendation:

1. Create 2 files, XXX_Prod and XXX_Test.

2. Start working on the Fuselage. If you have a good quality drawing, then you can turn it into an SVG file and continue from there. Check this out.

3. Don't forget R.U.L.E #1!

4. Build all the parts In-place.

5. Work on the Test file first and when you are happy with the results, re-create it in the Prod file. This way you will have a nice and clean assembly file.

6. When you are done, Don't forget to invite me for a Ride 😉

If you have any question, don't hesitate to ask.

Cheers / Ben.