Slicing a cylinder you should get an ellipse. In this case you'd be slicing the motor mount as your cylinder. Then you'd get your ellipse and could draw that and transfer it. 🙂 Just one way to do it - I don't know how Doug did it though.

Edward

I would bet looking at what Doug has shown that he drew things up in either Solidworks or Pro/Engineer and had the software figure out the intersection shapes and possibly even make cutting templates or exported it to an NC tooling package like MasterCAM to cut the parts on an appropriate machine tool. That's what I did with the machined parts in my L3 project.

Warren

a.) how did you discern the pattern for cutting the tapered holes into the bigger tube? I assume this mathmatically derived... I'm just curious how you even begin to derive the pattern for where to make the cuts?

Technically an ellipse is a plane intersecting and a cylinder and this it a cylinder intersection a cylinder. However, I did draw half an ellipse with a width the thickness of the 38 mm motor tube and (half) the length is the height it went into the body tube.

b.) how did you actually cut the FWFT? what tool did you use?

After making the pattern I cut the opening with a dremel tool and a diamond blade. Then I grind out the to the final shape with a sanding or diamond bit. It did take many test fits until it fit. The body tube is actually glued on now but I don't have an updated picture yet. This project was put on hold for a while.

I'll post a few more pictures here shortly.

Doug

BTW, this project is called Double Feature named by John Wilke.

Here is looking up the old wazoo. There are spars that run from the center motor mount tube to the outboards.

A shot of the motor mount tubes without the skin and the skin by itself.

Here is a shot of the fins for the booster. And yes they are through the wall mounts and No I can't describe how its done.

Doug

Doug, as always, I stand in awe of your projects. I thought I was gonna be the new cool kid at the launches with my NC machined parts. You've gone far beyond that.

Warren

BTW, this project is called Double Feature named by John Wilke.

Glad I could help 8) I'll get out of your way now.

This is probably the most complex rocket I've ever seen attempted? I feel like a total hack when I see something like this.

We have some real talent in the club. Joe and Ed's Saturn V, as well as a host of other projects are just so incredible.... it is a real treat to see these things. Doug, you have raised the bar -- for all of us.

JW

drew things up in either Solidworks or Pro/Engineer and had the software figure out the intersection shapes and possibly even make cutting templates or exported it to an NC tooling package like MasterCAM to cut the parts

Actually don't use nearly that fancy tools. I only use Visio for drawing out the designs but I certainly don't have access to a CNC machine. I have to borrow use of a lathe. Other than that I use mostly a drill press and sanders. Thanks for the nice comments but as JW pointed out this is a very complicated project so it may take a while to finish.

Doug

Well Doug, you have even more admiration from me - I've been using the cool tools since I've had access to them and would have thought you had some access to them given your job. Even more power to you doing all that stuff manually. As John said, you really know how to raise the bar for everyone. I can't wait to see this project fly.

Warren