A photo of my new pod.

[Tony D.]

I am redsigning my Holmes TD glider and decided to go with a pod and boom arrangement so I made up a mould for the pod first.

I used balsa for the plug and glassed it then laid the tool up in the usual manner. Length is 395mm.

I went with an oval cross section for something different.

This is the first part out of the tool and I am really happy with the way it came out.

This one is 4 layers of 60gr/sq/mtr Kevlar and I cut some strips of carbon uni and wove it into the layup. Painted in the mold except where I masked it off for the fibreglass wrap I will use to attach it to the boom.

Very light and extremely stong.

Instead of using storebought carbon tube I am going to lay up a mould using a 25mm wide by 20mm high oval plug and lay up oval cross section carbon tube fuselages. I will post a photo when I have that tool made and the first part pulled.


T.D.

[Salto]

Tony,

Nice work!! Is the white colour gelcoat? Or some sort of paint?

Did you split the mould? How did you handle the seam on the part?

Graham.

[Tony D.]

Hi Salto,

The finish is the new Krylon Fusion spray paint, a huge improvement over regular Krylon. I highly recommend it. And it looks great on bagged wings to.

Instead of having a centre seam on the top and bottom of the part I split the mould on the sides but I didn't use a splitter plate, I just laid the plug sides on a waxed board and laid up over them.

This part is a wet lap seam but I think from now on I will use seam tape.

I made the tool so that I can either cut out a hatch or lay up a nose cone type pod ala Dr. Drelas instructions on the SuperGee.

Speaking of the SuperGee pod, that was the inspiration for the shape, I added width and lots of length and flattened the top and bottom a bit but credit for the basic shape go to Dr. Drela.


Tony D.

[awmeade]

Hi Tony.

Firstly, great looking pod - I'm sure it will serve you well!

Now onto some questions - hope I make sense :
Did you saw the male plug in half after shaping then, or was it "pre-sawn" and dowelled together for shaping?
Did you join the two female halves together with the pod halves still inside them and wet? Did you use a datum of some kind whilst squeezing the mold together?

I guess what would really explain it all would be a couple of pictures of your waxed board, female molds, and male plug if that's OK?

Many thanks for sharing your work.
Andy.

[nuevo]

nice work Tony. Your finish shows off top quality job you did building the plug & mold.

[Tony D.]

Hi Awmeade,

"Did you saw the male plug in half after shaping then, or was it "pre-sawn" and dowelled together for shaping?"

I started with two 25mm thick pieces of balsa and I tack glued them together with a bit of thick CA, 3 small dabs are all you need. I drew out my plan laid it on the balsa cut it out on a band saw and sanded it to the finished shape. But with balsa you don't really need a bandsaw, you can sand it to shape by hand or a disc sander very easily.

Then I broke the two halves of the pod apart and laid up a layer of light glass over the them (on the surface that is used to make the mold only not the flat back that goes against the waxed board) let this cure and sanded, filled as needed and wet sanded untill a glossy finish was achieved. Then I applied six coats of parting wax buffed between coats.

I waxed up a flat piece of MDF with a small un-waxed section that will be used to tack glue the plugs to the board. So when you wax your MDF or whatever you use leave a 10mm wide by say 100mm long 'slot' unwaxed so you can use CA to tack your plug halves down.

Tack glue the plug down to the board and apply a coat of PVA let dry and lay up your tool.


"Did you join the two female halves together with the pod halves still inside them and wet? Did you use a datum of some kind whilst squeezing the mold together?"

The pod in the photo I posted was laid up with a wet lap seam so yes they were joined while in the mold.

To make sure the mould halves will 'register' I re-glued the plug halves together placed the plug back into the cured mould and drilled holes through both sides of the mould flange so when you are laying up all you have to do is register the screw holes and you know your halves are in alignment.


"I guess what would really explain it all would be a couple of pictures of your waxed board, female molds, and male plug if that's OK?"

Here you go: Sorry for the quality of the photos, in the joined plug photo you can see the line where the halves are glued together for shaping and final mould registration with the screw holes. The photo of the mould halves was taken just after I removed the plug and before it was trimmed and cleaned up.

Hope this helps.



T.D.

[awmeade]

Tony,
Thanks for taking the time to explain that through - much appreciated!

I'm building up to do a pod of my own for a DLG, so just trying to "get my head around" all the different moulding processes that can be used - your's is one I have read about, but not fully grasped in the past. It also seems to be the most straightforward.

Many thanks again for sharing the technique - I'm sure the rest of your model looks as nice as that pod.

Cheers,
Andy.