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Diy CNC 4 axis hot wire cutter

Wayne

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Yep - Looking good. I think you may have issues with the foam you have used, the plane will not be lasting very long. You may want to consider sheeting it in some 64th plywood if you can find a cheap source for it. Then it should be a rocket and last a while.
Time to find a source for EPP foam and calibrate the cutter for it. Just be warned that you will want good ventilation when cutting EPP, it is nasty stuff to inhale.

Using your current foam, I suggest building something like the early Alula. It will be super light and fly GREAT! I think they used the PW51 airfoil with great success. Probably does not need any covering or spars in it either, may just a strip of tape at the leading edge. A Mini Alula might be pretty cool too, maybe 75% of the size with very lightweight radio gear. Hmm.. :)
 

thenated0g

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EPP is so expensive though. Compared to one epp plane order i could make 20 planes out of this foam. I find that uncovered the foam is extremely flimsy...flops around. I will have to try it on a small plane. Putting in glass fiber spars top and bottom and than wrapping the entire wing in filament tape and laminate seems to make these things tanks. Even on my 90" flying wing you could hold it from the wingtip on one side. Thats a 3kg wing lever. I have epp planes and they are pretty amazing no doubt the but cost is just too much for me. This home depot foam is lighter and stronger than epp. Stiffer? Right up to the point it snaps in half and becomes pop corn. For somebody that builds more than flies its pretty great.

I usually do 5mil laminate, but trying some hobbyking iron on film this time, over the tape.
 

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Wayne

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Yep, but the nice thing is the EPP will last years of TOTAL abuse. :)

Keep an eye out for EPP, you may find some good scraps or something in the local area. Never know. But if you have to buy the stuff it can be spendy, that is for sure. On the plus side, you might be able to sell some wings to offset the expense..

There are many different foams. The foam use are currently using is very similar to what PSS and DLG guys use in their wings. There are different densities available and slightly different mixes that will have different attributes. Always keep your eyes peeled for chunks of free foam. But be warned, foam from an old boat dock should probably be avoided. It can have all sorts of junk inside that will mess up your CNC, and it can actually become water logged also. Typically it is the lowest quality stuff you will see out there.

Don't be afraid to sheet some wings with thin balsa, you will end up with a very nice wing!
 

thenated0g

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We got evacuated (all of lakeport, ca) for an entire week and than its been a few weeks of getting back to regular life and dealing with tons of smoke. Havent really been motivated to do anything rc. This is some footage from right before the fire. This is my first time using iron on color laminate, like you would use on balsa planes. Usually i would cover with 5mil iron on "new stuff" style laminate for wings. Really like the color. A little harder to use ad the temp range is much more sensitive compared to the clear stuff. But a heat gun tightens it up and it looks amazing. Colors really pop. Other side is going to be a silver color.

 

Wayne

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Looking good. Glad it was only an evacuation for you. Would be nice to get these pesky fires out, seems like they have been going on forever.
 

Wayne

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Ahh, that silver/grey should match the smoke haze very nicely. LOL

A word of warning - Not sure what film you have there, but some silvers and metallics of cheap films or vinyls will actually block 2.4ghz antennas very effectively. Do a little range check before flight. :)
 

thenated0g

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oh man, thats a good point. Probably just bring the antenna to the surface and clear film it to be safe. I still need some nose weight as cg is about an inch behind where i need it, but currently its sitting at about 8oz sqft/ 3.99 cubic loading. Going to try a different take on balast weights as well. Using the copper pipe inside some carbon from you guys but skipping the lead melting and instead just mixing up some epoxy/bb slurry to put in the copper.
 

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Ahh, you wont like this answer, I just fly it. :)

I should have had you pick up one of the PSS planes in my office when you were here. It always surprises people with how heavy it is, and it does not have any radio gear or the plank of steel that is used for ballast. For gliders we range from as light as possible to as heavy as practical. Each slope can handle a different level of wing loading on their best days. So it is kind of like golf clubs, different clubs for different jobs.

-Wayne
 

thenated0g

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I have been using the cubic loading. Not to know how it will fly at a specific slope, but more just to see how it compares to my other planes. Than i kind of know "ok its going to fly like that did".

I am interested in those old pss kits you have been just storing in the back. Send me some pics sometimes.
 

Wayne

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They are more of the offerings from Magnum Models. We never got them up on the site, then he closed down his business for a while. He back open again, so we should add them back to the site. I don't remember what all they are anymore, but I think some of the bigger PSS planes and some of the sport items like the Duster.
 
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