PsyBorg
Wake up! Time to fly!
I don't see that working so well with something over 20 pounds!
What? You has no faith in gimpy n lurch having the strength to chuck this in the air?😉
Just funnin guys.
Monster sized Fock-Wulf FW-42
- Thread starter rockyboy
- Start date
What? You has no faith in gimpy n lurch having the strength to chuck this in the air?😉
Just funnin guys.
Oh yeah - and the inevitable hospital visit too!
Just build a scaled up version of the @Hai-Lee bungee launcher. 20lbs - how hard could it be?
So the weather finally warmed up and I went for it - below is the mold filled with layers of fiberglass & epoxy, then a layer of plastic wrap and filled in with heavy aquarium sand to keep it all pressed tightly into the mold.
So the experience of doing this was a little nerve wracking - it was very tricky to get the layers to stay in place against the walls of the mold, every time I pushed one side in it would pull away from the other wall. I was able to finally get it pretty much in place - three layers of 3/4 ounce up against the wall, and two layers of 2 ounce glass for strength next.
We'll see how it comes out - no matter the outcome it's been a learning experience!
So the experience of doing this was a little nerve wracking - it was very tricky to get the layers to stay in place against the walls of the mold, every time I pushed one side in it would pull away from the other wall. I was able to finally get it pretty much in place - three layers of 3/4 ounce up against the wall, and two layers of 2 ounce glass for strength next.
We'll see how it comes out - no matter the outcome it's been a learning experience!
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I'm planning to give the epoxy a full 24 hours before disturbing it - so more news on this adventure tonight
Also, I just noticed the excellent shot of the orchid soil in the background there. After killing orchids reliably for well over twenty years with benign neglect, we finally have one producing lots of big blooms - and I have to give credit to this soil. So if you've ever bought your wife/girlfriend an orchid, be a hero and transfer it to a bigger pot with this soil. It'll make her smile, which helps her tolerate crazy big airplane projects
Looking a little sketchy, but not too bad once I pulled out the gravel and plastic wrap. The epoxy cured very nicely - not sticky at all. You can see where excess epoxy puddled at the front of the cowl from the inside though...
And here's where I'm stuck. I cut off the raggedy edges so I could get a spackle knife between the cowl and the mold and the sides separated very easily! But the flexibility isn't there in the corners so they are still stuck and the nose is firmly staying put as well. I've tried pulling on all four sides with pliers, and using compressed air to blow it out. All that happens is the little flaky film of the mold release agent comes shooting out all over the place - but the bottom and corners are staying put.
Looking for other suggestions on how to deal with this without destroying the mold. Thinking if I can get a pretty good idea of where I'll be drilling the front of the cowl for the prop, I could drill in from the outside or the inside just to the layer separation and try to blow air directly into that front nose section. Appreciate other ideas though.
I do still have the plug which is in great shape, so if I need to destroy this mold to get the cowl free I can make another one. But I'd like to avoid that if I can.
And here's where I'm stuck. I cut off the raggedy edges so I could get a spackle knife between the cowl and the mold and the sides separated very easily!
But the flexibility isn't there in the corners so they are still stuck and the nose is firmly staying put as well. I've tried pulling on all four sides with pliers, and using compressed air to blow it out. All that happens is the little flaky film of the mold release agent comes shooting out all over the place - but the bottom and corners are staying put.
Looking for other suggestions on how to deal with this without destroying the mold. Thinking if I can get a pretty good idea of where I'll be drilling the front of the cowl for the prop, I could drill in from the outside or the inside just to the layer separation and try to blow air directly into that front nose section. Appreciate other ideas though.
I do still have the plug which is in great shape, so if I need to destroy this mold to get the cowl free I can make another one. But I'd like to avoid that if I can.
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I've seen folks use an air compressor and a thin nozzle and try to get some separation that way. Drilling into the mold in the front (likely where it will be trimmed anyway) and using compressed air may work too. I do wonder it using heat might crack the mold. You might also consider cutting the cowling in one spot so you can flex it and get it loose, then going back and putting a strip of FG on the inside over the seam. You'd still have to deal with the seam when you prep for paint, but it might make it easier to get out.
Just a few thoughts.
Just a few thoughts.
I hadn't thought about making a cut on the side of the cowl - that could allow me to get the vertical corners free, which might be the chain reaction to get it all out! I'll just put the seam on the bottom and it'll be fine
Thank you!!
HilldaFlyer
Well-known member
Inside molds are really tricky. Looks like you're getting the hang of it.
You might try building a couple of fake cowls with foam board, remove the paper from the outside, fiberglass over the foam and then remove the foam. Foam separates pretty nicely from fiberglass, and if it doesn't, just hit it with some acetone. I'm sure you can whip up a couple of foam board cowls in a minute or two.
You might try building a couple of fake cowls with foam board, remove the paper from the outside, fiberglass over the foam and then remove the foam. Foam separates pretty nicely from fiberglass, and if it doesn't, just hit it with some acetone. I'm sure you can whip up a couple of foam board cowls in a minute or two.
Inside molds are really tricky. Looks like you're getting the hang of it.
You might try building a couple of fake cowls with foam board, remove the paper from the outside, fiberglass over the foam and then remove the foam. Foam separates pretty nicely from fiberglass, and if it doesn't, just hit it with some acetone. I'm sure you can whip up a couple of foam board cowls in a minute or two.
I'm thinking about doing that instead of the mold step - I've already got the foam plug done. It would require a lot more finish work to fill and sand the weave on the cowl that way, but I don't have to make a mold which is a pretty good trade off. Also, trying the second one with this method gives me a good comparison of the two techniques so I'll know how I want to do future cowls, like the one I'll need to make for the Dreamer Bipe project.
HilldaFlyer
Well-known member
Nice!
What weight of cloth are you using? A couple (three) layers of 0.7 oz (or there abouts) would do the trick and the weave is so small, you could sand out the top layer pretty easily. That or the old light weight Spackle.
Nice!
What weight of cloth are you using? A couple (three) layers of 0.7 oz (or there abouts) would do the trick and the weave is so small, you could sand out the top layer pretty easily. That or the old light weight Spackle.
I did the first one with two layers of 3/4 ounce and two layers of 2 ounce - and it's certainly overkill. Much thicker cowl than is necessary.
I think I'll give the three layers of 3/4 you suggest a try and see how it rolls!
HilldaFlyer
Well-known member
Just had and idea that, not that you should do, but something I should try. If anyone following this thread has tried, I'd be interested in knowing the the outcome... 3D print the inside mold, overlay the mold with plastic wrap or some barrier, wet out fiberglass overlay and cure under vacuum. I think this would make a really thin, light, form-fitted cowl.
I think that could work very well - just need to pay attention to the 3D printing infill amounts to resist crushing under vacuum. Not the time to save filament with a 5% infill
