F106A

My Feedback: (2)

Hi,
I was wondering which is better, C/F or Kevlar for repair and/or reinforcement.
I know C/F soaks up a lot of resin and as a result, heavier, but was wondering what are the advantages/drawbacks of either material.
Thanks,
Jon

David Searles

My Feedback: (49)

Jon,

Carbon fiber should be used where your primary needs are strength and stiffness. Use Aramid/Kevlar when primary need is toughness abrasion resistance. Carbon fiber is also easier to work with. Kevlar needs very sharp shears to cut and sands poorly. Carbon fiber sands quite easily and feathers well.

David S

rbxbear44

My Feedback: (86)

+1 with David. Also, CF is not (typically) uni-directional like Kevlar is. If I am repairing or strengthening in a "twisting area", I use Kevlar. For downward/upward force stiffening, I use CF.

Rex

mitchilito

My Feedback: (7)

One big advantage of Kevlar is the fact that is doesn't block 2.4ghz radio reception. As previously mentioned, one big disadvantage is that you just can't sand it at all. Lately I've been avoiding carbon for better radio reception.

speedracerntrixie

My Feedback: (29)

Depending on the type of repair you may not want to use either. If you can do the repair with multiple layers of light fiberglass with each layer gaining 20% footprint it may turn out lighter and better distribute the load.

Turbotronic

One of the advantages of Kevlar is its tear resistance. Any part of a composite airframe that is likely to tear in a case of bad landing etc could do with some kevlar.
On my very first jet, a foam core balsa winged spectre the area between TE and wheelwell would crack sometimes. Glass and carbon did not help.
Kevlar cured it.
Andre

RAPPTOR

My Feedback: (41)

++++ 1 DAVID FOR SURE..

RAPPTOR

My Feedback: (41)

IT SANDS FINE.. JUST WARE MASK

Carbon-Customs

kevlar DOSSENT sands "fine"

i cant see wehre we need kevlar in our models.... fiberglass and CF is plenty..

and remember yes CF takes alot og resin, but 100grams of CF is stronger than 400 grams of fiberglass

DiscoWings

My Feedback: (76)

You can always get kevlar/carbon wave and get best of both worlds.

mr_matt

My Feedback: (10)

Unless I had no alternative I would not use Kevlar anywhere, not worth the headaches.

Hard to cut the fibers, hard to wet out with resin and terrible to sand or abrade post cure.

Ron Stahl

My Feedback: (12)

Carbon fiber contrary to what has been posted does not weigh more becuase it soaks up resin. All composite cloth is specified by weight per square yard, weather it be fiberglass, Kevlar, or carbon fiber six oz cloth is six oz cloth. If it weighs more you are using way to much resin to wet out the cloth. What we do is weigh the dry cloth before a repair or build and then measure out a specific amount of resin to wet the cloth out to control weight. The thinner the resin the easier it is to wet out the cloth no matter what type it is. We have found that MGS resin from CST or Aircraft Spruce works best for laminating, however it is expensive to buy and ship for a hobby level use. If the resin you are using is thicker than you would like it to be you can mix some denatured alcohol to thin it down. The alcohol will flash off leaving the resin. Also if you have access wet the cloth out on a piece of monocote backing plastic and squgee it out, then transfer it to the repair area this will allow ou to make sure the cloth is wet but not overly so.

RAPPTOR

My Feedback: (41)

CANT SAND KEVLAR.. I MENT CARBON