rdefrei2

My Feedback: (6)

I'm looking to make a 1/4 scale fuselage with some CF reinforcement and would like to have some advice on the Fiberglass cloth that I should use it.

I use to laminate fuselages about 10 years ago and know I don't remember wich "oz" fiberglass cloth should I buy it.

I do remember that I use to laminate with Epoxy resin but I don't remember if the cloth use to be 6 or 10oz or 12oz.

Anyone have any ideia which fiberglass cloth weight should I get it...??

Thanks,

soarrich

My Feedback: (98)

I'd go with the 6oz from you selection, but I would also get some lighter stuff too.

I'm not a fan of mixing CF in with glass, it just means the CF carries all the load until it fails the the glass fails.

Ed Smith

Maybe I can address both points.

The pictures will show.

The fuselage is for a 1/4 scale Cosmic Wind Pylon Racer. The first layer of glass in the mold was 3oz crowfoot cloth. This cloth gives a fairly tight surface with very few pinholes. The second layer is 6oz cloth. A third layer of 6oz goes from just ahead of the firewall to the wing saddle L.E. This stiffens up the motor area. What is then needed is a way of stiffening the fuselage sides to prevent "Oil Canning" without adding weight. This is where the intelligent use of mixing Carbon with glass will provide the desired result with very little weight gain. The carbon tow is wound ito a string and squeegeed into place. Very little extra resin as added as the carbon soaks up some of what is already there. When the fuselage is joined one would swear there are formers not just carbon in those positions. Anybody who rejects the use of carbon has never used it, or never used it properly.

The cowls are 14" long, here carbon is used to prevent them for caving in with the force of the attachment fastener. Eventually most wheelpants tear away from the L.G. After two years mine are in good shape due to the carbon reinforcing. It must now be obvious that I swear by the proper use of carbon materials. I use MGS epoxy resin throughout.

Enjoy.

Ed S

soarrich

My Feedback: (98)

Kind of a bold statement.

Your CF is used to locally stiffen your pieces, they are not carrying the loads on the fuse.

KC36330

it's bold because it's true. carbon provides a much needed stiffness and load carrying capability to the area in which it is used. on jets we use it in high load areas around the landing gear as you're asking that area to take the force of a 25-50 lb dry weight aircraft and hold up to all landings, some of which may not be perfect. then again around the gear doors to provide stiffness and down the length of the fuselage to prevent flexing. when you've got 3 lbs of batteries in a nose cone that's 45 inches in front of the wing fiberglass alone will not hold up to the wind force of 200 MPH much less any G's being pulled. there have been countless episodes where carbon wasn't used and during flight a canopy / hatch openings flexed enough to allow the canopy / hatch to depart the aircraft, at speed the wind force into the fuselage after loosing one of those can/will causes a catastrophic explosion of the fuselage, it's not a pretty site.

there's at least 14 pieces of carbon tow in Ed's pics that are for support of the flying load and not just to stiffen the fuselage.

Ed Smith

Based on experience I offered advice on the suitable weight of glass cloth.

I do not know why I am having this discussion. Did you not notice the three strips of carbon above the Landing Gear position? This is a fairly heavy airplane and lands fast. The fuselage has not crumpled yet.

Not satisfied? how about the front end of these two Pylon Racer fuselages. Are they load carrying enough for you?

I am finished with this.

Ed S

SCALECRAFT

My Feedback: (13)

Hi All

With all due respect to the methods mentioned here, carbon is a good stiff material, but if one configures his glass lay up to create stiffness, carbon in not needed nor the expense.

Not much weight gain either. Around 3,4 times the stiffness.

I have carbon fabric in all its configurations, even the awesome carbon/kevlar hybrid stuff, and yes, I figure I know how to use it, but don't have to for a fuse.


Over the last 20 years, my buddy and I have had great success with hollow glass wings,(not sandwiched) fuses, stabs, spinners, props, to this day. All of glass only.

And remember, your building light and to avoid in flight failure.It will never be crash resistant.

I try to find the pic of my configuration on my 69" span all composite spitfire fuse.

What fuse is it, that would help the configuration.

Steve

rdefrei2

My Feedback: (6)

Hi Steve, it's a P-51 Fuse.

How do you make your hollow glass wings..??

soarrich

My Feedback: (98)

These might be of interest to you.

http://www.youtube.com/watch?v=_DDN-...eature=channel

http://www.youtube.com/watch?v=FCivv...eature=related

KC36330

I'd much rather see one of your all composite turbine designs that doesn't require carbon in the fuselage.

SCALECRAFT

My Feedback: (13)

Funny you should mention that. I'm working on one now. F-16. Kevlar will work too, and is way more impact resistant. And lighter. But I'm not going to use composites, I'm going to use ply framing to spread the load over a larger area. I may make my framing absorb shock as well in case of a hard landing. And I'm using epoxy resin, again, more inpact resistant then polyester. 99% of the Chinese jets are poly

KC36330

I've owned just about every F-16 out there and only a few were polyester so which MFG's in particular are you referring to?

SCALECRAFT

My Feedback: (13)

Hi

Here 's a pic of a 69"composite spitfire wing mold. For the sake of discussion, I will attempt to describe what works for us in the all composite model concept. Maybe with additional input , the quality of this method may improve with something I never thought to do.

Basically, we thought of the real airframes of WWII sheeted with Aluminum (or fabric, or wood) and thought, "why can't we have minimal framing for flight covered with a glass sheet. Hence the wing mold with wood framing.

If you can see the lines in the mold, you'll see where the framing will go. The wing is strong enough to support all the forces in flight, yet light enough to work.

The critical sections would be gear plates and ribs, spar 1,2,ect flying surface archoring, and wing bolt anchors, all tied into each other.

vacuum bagging is an option, but i don't use it, costs more and in this application does not yield enough of a result for me to use.

And composite models are resistant to hanger rash. I have dropped my epoxy components many times and they just bounce. poly resin will crack after time.

Youtube has many methods now to show one how to do this.

Steve

combatpigg

My Feedback: (3)

CF is 2/3 the weight of FG, has 1/2 the tensile strength but twice the compressive strength. It is used by pylon racers who find themselves in the winner's circles, where the airframes get put to the ultimate tests. Sport flying "what ya brung" is one thing, but the pylon type construction didn't just happen over night, it is highly evolved over decades of successes and failures.

SCALECRAFT

My Feedback: (13)

Good to know, but ................

Note the application in question is for a 1/4 scale warbird.

Steve

combatpigg

My Feedback: (3)

It' s very easy to go over board and end up with a model that it too heavy. My definition of too heavy is subjective.
The proven combination of layers and spot re-enforcements shown in post #3 will get this guy going and also gives me a better idea of what is needed for lightness and strength if I ever take on such a project.
If you've got a process that doesn't use carbon, that's great..how do you do a lay up this size?

SCALECRAFT

My Feedback: (13)

Hi

I know the ones that are epoxy resin. Jet Hanger imported models, Yellow, and locally BVM. Most others I believe to be poly. If they are epoxy, then we know its probably a low grade epoxy out of China. It wouldn't be unheard of.

I could be wrong, I do some research.



Steve

KC36330

you might wanna do that research long before you post such comments as very few of the China imports are polyester..........

SCALECRAFT

My Feedback: (13)

KC


Help us out here. How do you check to see if you have epoxy or poly??.

I sand the fuse somewhere it won't matter. If it smells like bondo, its poly.

Steve

KC36330

polyester has a sweet smell, epoxy has no smell when cured.

rdefrei2

My Feedback: (6)

What's the easiest way to add pannels to the fuselage....??

Should I do it on the Plug or on the mold...??

I've seen some kits that have all rivets, pannels and some screws on it.

soarrich

My Feedback: (98)

You do it on the plug.

invertmast

My Feedback: (23)

ROFLMAO steve.... Try that with a composite arf model and you wont be singing the same tune...

SCALECRAFT

My Feedback: (13)

I'm basing my statement on durability on our high grade epoxy (West sys, US composites) resin composite models, seamed properly, not the low grade Chinese epoxy or poly ones. Built in a hurry under mass production.

But painted very nicely.

I have a few Chinese arfs. There"s a difference.

Big difference in the epoxy.

Steve

SCALECRAFT

My Feedback: (13)

Ok, some pics of a few really old plugs to show the scribe line results and some minor alum duct tape panels. NOTE: These are wood plugs and around 19 years old.

A 50" span Zero 48" span FW 190A. Both have glass wings.

The wing mold is of the glass 109F, 48.5" span. The ribs are cut with a Carvewright CNC router for home use sold through Sears. really nice not to have to cut wood. I'm making another one, my test one needs a paint job.

The Brown/Blue 109 is my personal test one.

Hope the pics load.

Steve


Just remembered the 109 wing mold is Devcon epoxy from Graingers. Makes a good surface coat. It has milled aluminum in it. Durable but expensive. Not a must, but kinda premixed surface coat. No need for cobosil or pigment to make a surface coat.