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  • January 25, 2022, 01:30:50 AM

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Author Topic: Carbon gear (update)  (Read 831 times)

Offline Dwayne Donnelly

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Carbon gear (update)
« on: January 08, 2022, 08:48:16 AM »
Hi all, I'm going to try and make my own carbon gear for 40 size stunter around 48 oz. , please what thickness (weight) of carbon should I buy.
Thanks  y1
« Last Edit: January 15, 2022, 07:12:25 AM by Dwayne Donnelly »
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Offline Dwayne Donnelly

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Re: Carbon landing gear
« Reply #1 on: January 10, 2022, 01:47:53 PM »
https://www.ebay.com/itm/224278294126?hash=item3438072e6e:g:QfUAAOSwRJpdPmzO

I would go with the 16mm width. You can use even wider stuff and pull it apart if you need smaller strands for the bottom part.

Motorman 8)

Thanks Motorman, I ordered some and got the shipping details today, it will arrive sometime around Apr 11.  :o  %^@ Say what? LOL Where's it coming from Mars?  n~  I'm sure they're covering their behinds and it will be here much sooner..lol
« Last Edit: January 10, 2022, 02:35:50 PM by Dwayne Donnelly »
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Offline Dave Hull

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Re: Carbon landing gear
« Reply #2 on: January 10, 2022, 04:53:12 PM »
Coming from China....

Offline john e. holliday

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Re: Carbon landing gear
« Reply #3 on: January 11, 2022, 11:13:17 AM »
Yeah Biden's country,  three months now and my item is in shipping phase.  Maybe USPS dumped it some where. S?P
John E. "DOC" Holliday
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Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Online Howard Rush

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Re: Carbon landing gear
« Reply #4 on: January 11, 2022, 01:00:01 PM »

Never mind.
« Last Edit: January 11, 2022, 01:32:25 PM by Howard Rush »
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Offline Serge_Krauss

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Re: Carbon landing gear
« Reply #5 on: January 11, 2022, 03:29:14 PM »
Blame the person who damaged the institution, if you must.

Offline Dwayne Donnelly

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Re: Carbon landing gear (update)
« Reply #6 on: January 12, 2022, 06:39:15 AM »
CF state side is awful expensive. China has great prices but order well ahead of need.

If you're new to making parts this way, a good way to get started is make parts out of fiberglass. There is a boat repair yard near me that sells left over sheets of woven roving pretty cheap. You simply pull the thick strands out of the cloth and spread them out a little with your fingers. I've made many props this way.

What glue are you using for the gear lay up?

Hobby king has all kinds of CF landing gear for profiles and full fuselage but I could never figure out their measuring system.


Motorman 8)

Thanks, I think practicing with cloth first might be a good idea, I haven't decided  on a glue yet, Sparky uses a 2:1 resin but there's a thread on a rc boat forum saying Z Poxy finish resin works good as well, I have lots of Z Poxy so I'll try that first.
« Last Edit: January 15, 2022, 06:16:58 AM by Dwayne Donnelly »
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Offline Mark wood

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Re: Carbon landing gear
« Reply #7 on: January 12, 2022, 08:27:37 AM »


My $0.02 FWIW. While plain tow would work, I probably wouldn't use it but maybe I would, I dunno, it would depend on what I have on hand at the time when I decided to make the part. I would use a unidirectional mat fabric which is preformed as it is easier to work with for this application. Raw tow is good for forming "forged" parts like propellers. Using the Uni fabric you can readily tune your laminates for the application and cut them to size which improves your layup quality. I'd also use West Systems. Have I mentioned I'm a fan of West Systems? The WS epoxy responds well to post curing "tempering" which will make a for a super nice gear part. Post curing at 160F for a couple hours will go miles to making your part durable. I also really like the EPON resin systems but it is expensive for this application. WS isn't cheap but it works very well for most everything we do, the only drawback is cure time. The 2:1 resin to CF ratio is very high and can lead to cracking. The Z Poxy is not  very stiff, so that may mitigate that some. Generally 1.1 - 1.2 : 1 is the right ratio resin to CF.

Here's a link to some uni CF fabric and it seems to be in stock. https://compositeenvisions.com/product/carbon-fiber-fabric-uni-directional-12k-12oz-404gsm/

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Offline Lauri Malila

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Re: Carbon landing gear
« Reply #8 on: January 14, 2022, 09:12:36 AM »
The flat tow is absolutelbytely the best for that use. And it's very easy to handle and cut, too. Also, the Toray T700 is not a bad fibre. L

Offline Mark wood

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Re: Carbon landing gear
« Reply #9 on: January 14, 2022, 10:20:20 AM »
You can also do that with tow. The longest strands would make the outer casing and the inner strands would be various lengths to serve the taper. Tow would have a strong strand orientation.

Motorman 8)

I realize that and having worked a lot with both, I would use the fabric since it's much easier to handle for this application. With tow it can be a big mess and the mold gets complicated like a prop mold. For a simple lay up like this the fabric is much easier. I make "prepeg" layups for this kind of part. I lay the fabric out and wet it out. I also use an ink roller to spread my epoxy which insures I have a good resin fiber ratio. I then cut my "prepeg" to the final size and lay in place. That can't be done with tow easily. Of course in my case, I generally have all of these on hand including a selection of resins to choose from. In another situation, I would probably make do with what I had on hand but I'm not so I don't have to choose. In a situation where I didn't have the materials on hand and needed to make a decision of what to use, I'd go with the fabric. That's my point. Use what ever you wish or have on hand or makes you happy.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Mark wood

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Re: Carbon landing gear
« Reply #10 on: January 14, 2022, 10:21:13 AM »
The flat tow is absolutelbytely the best for that use. And it's very easy to handle and cut, too. Also, the Toray T700 is not a bad fibre. L

Yup.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline pmackenzie

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Re: Carbon landing gear
« Reply #11 on: January 14, 2022, 10:45:28 AM »
I realize that and having worked a lot with both, I would use the fabric since it's much easier to handle for this application. With tow it can be a big mess and the mold gets complicated like a prop mold. For a simple lay up like this the fabric is much easier. I make "prepeg" layups for this kind of part. I lay the fabric out and wet it out. I also use an ink roller to spread my epoxy which insures I have a good resin fiber ratio. I then cut my "prepeg" to the final size and lay in place. That can't be done with tow easily. Of course in my case, I generally have all of these on hand including a selection of resins to choose from. In another situation, I would probably make do with what I had on hand but I'm not so I don't have to choose. In a situation where I didn't have the materials on hand and needed to make a decision of what to use, I'd go with the fabric. That's my point. Use what ever you wish or have on hand or makes you happy.

One problem with fabric in this case is that 1/2 the fibers are going in the wrong direction, just along for the ride.
You need a few cross fibers to keep the gear from splitting, but the rest should really be in the long direction.
Cloth on the outer layers (if only because it will look nice :) ) and uni for everything inside would be what I would try.

There are some very unbalanced cloths that could also be used. I have some old Russian stuff that just has little cross ties of glass.
MAAC 8177

Offline Mark wood

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Re: Carbon landing gear
« Reply #12 on: January 14, 2022, 10:57:14 AM »
One problem with fabric in this case is that 1/2 the fibers are going in the wrong direction, just along for the ride.
You need a few cross fibers to keep the gear from splitting, but the rest should really be in the long direction.
Cloth on the outer layers (if only because it will look nice :) ) and uni for everything inside would be what I would try.

There are some very unbalanced cloths that could also be used. I have some old Russian stuff that just has little cross ties of glass.

Not exactly. Unidirectional fabric like what Laurie and I provided the links for are not biased weave as you assumed. Yes a cross weave something is good to handle the shear but the shear in this application is not very high. One ounce fiber glass works well for this but biased CF would have more curb appeal. I use the 1 ounce weave glass in my props but layer it within the layup schedule so it doesn't look crummy. It is enough to keep the grain from splitting at the tips. I use this same unidirectional material in tail booms and any place the load is dominantly bending.

 
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline pmackenzie

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Re: Carbon landing gear
« Reply #13 on: January 14, 2022, 11:15:02 AM »
Doh!
I missed the part where you were talking about uni-fabric  :-[
I agree- much easier to handle than tow.
MAAC 8177

Offline Mark wood

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Re: Carbon landing gear
« Reply #14 on: January 14, 2022, 12:10:10 PM »
Doh!
I missed the part where you were talking about uni-fabric  :-[
I agree- much easier to handle than tow.

No worries... I'm probably more better at that than you Pat as I have managed to demonstrate consistently...  n~
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Dwayne Donnelly

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Re: Carbon landing gear
« Reply #15 on: January 15, 2022, 06:30:36 AM »
I took Motormans advice and did a practice run using balsa sandwiched in glass cloth with Z-Poxy, I've never done this before, never made a mold, nothing, I went to youtube found Sparky' video and another guy who used styrofoam clear tape and hairspray to keep it from sticking to the mold, and when Sparky says anyone can do this he aint kidding, I'm blown away by how easy it was and I can even reuse the mold.  #^ y1  ~>

A little back history on why I'm doing this, I built a Genesis 35 but opted for fuse gear instead of wing mounted beacause I fly on grass that is not always smooth, I made a set of aluminum gear but they look so out of place on a plane with such smooth lines, so I'm making a set that swoops back a bit and wheel pants to give it a better look, (at least in my opinion :D )

Anyway I'm actually excited to try the carbon fiber, one thing, the gear is 20 mm wide so I'm thinking the gear should be at least 1/8th inch thick, any thoughts?
Thanks
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Online Craig Beswick

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Re: Carbon landing gear
« Reply #16 on: January 15, 2022, 06:53:42 AM »
Looks good Dwayne. Sparky, John and Dan Winship have been working on a few composite things lately on Sparkys videos Saturdays at Johns.

From what I have seen of their landing gear they made the area to be fixed to the fuselage about 50%-100% bigger than the strut width, if that makes sense. I guess in your case about 30mm-40mm just to spread the load.

Craig
AUS 87123
"The Ninja"

Offline phil c

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Re: Carbon gear (update)
« Reply #17 on: January 23, 2022, 01:33:26 PM »
Hi all, I'm going to try and make my own carbon gear for 40 size stunter around 48 oz. , please what thickness (weight) of carbon should I buy.
Thanks  y1

You could probably get what you need from Advanced Composite Products- probably higher prices, but much faster delivery.
phil Cartier


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