---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Fri 03/11/05: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:15 AM - Kevlar (Pilots4ETW@wmconnect.com) 2. 06:03 AM - Re: Kevlar (Jim Markle) 3. 09:23 AM - Re: Some aerodynamic stuff (walt evans) 4. 02:50 PM - Re: Kevlar (gbowen@ptialaska.net) 5. 09:11 PM - Re: Kevlar (Rcaprd@aol.com) ________________________________ Message 1 _____________________________________ Time: 03:15:14 AM PST US From: Pilots4ETW@wmconnect.com Subject: Pietenpol-List: Kevlar I'm thinking of putting a couple layers of Kevlar on the fuselage tank I'm building to offer more safety over a simple fiberglass tank. I read in the Wicks catalog that Kevlar is 2.5 times stronger than E glass, and 10 times stronger than aluminum on a specific tensile strength basis. The problem is I don't want to invest in a pair of $60 scissors that will probably be used one time. Does anybody have any experience in cutting Kevlar with a regular pair of scissors or is there an alternative to the $60 version? Roy ________________________________ Message 2 _____________________________________ Time: 06:03:12 AM PST US From: "Jim Markle" Subject: Re: Pietenpol-List: Kevlar I have experience cutting Kevlar and the scissors are an absolute must. But don't buy any. I have a pair sitting here collecting dust and would be glad to loan them to you. Send me an SASE (and promise that you'll return them!) and you're welcome to borrow them. If you decide to buy some for yourself, don't buy the $60 ones....get the $26 ones from ACP (http://www.acp-composites.com/acp-ta.htm) Jim Markle Plano, TX 214.505.6101 ----- Original Message ----- From: Pilots4ETW@wmconnect.com To: pietenpol-list@matronics.com Sent: Friday, March 11, 2005 5:14 AM Subject: Pietenpol-List: Kevlar I'm thinking of putting a couple layers of Kevlar on the fuselage tank I'm building to offer more safety over a simple fiberglass tank. I read in the Wicks catalog that Kevlar is 2.5 times stronger than E glass, and 10 times stronger than aluminum on a specific tensile strength basis. The problem is I don't want to invest in a pair of $60 scissors that will probably be used one time. Does anybody have any experience in cutting Kevlar with a regular pair of scissors or is there an alternative to the $60 version? Roy ________________________________ Message 3 _____________________________________ Time: 09:23:40 AM PST US From: "walt evans" Subject: Re: Pietenpol-List: Some aerodynamic stuff Corky, My take on the down thrust of the engine is since the plane wing normally flies with some positive incidence, the engine/prop is flying with zero incidence. walt evans NX140DL ----- Original Message ----- From: Isablcorky@aol.com To: pietenpol-list@matronics.com Sent: Thursday, March 10, 2005 7:57 PM Subject: Pietenpol-List: Some aerodynamic stuff Pieters, As I build my engine mount jig some little questions have popped into this ole brain. I remember from a long time ago, maybe flight school or somewhere, that the downthrust angle on the engine is to force a more direct blast on the lower surface of the wing.(High, single wing). Now as I plan to extend the mount a full 2 inches forward of the plans and lengthen the cabanes another 2 inches over the plans. It would seem to me that it would be necessary to drop the engine incidence to compensate for these changes. Now those of you in the know please advise. I'm laying out the jig for a 4 degree downthrust measured from the firewall and a wing incidence of 1 degree 30'. Sure would appreciate some help on this one. I promise to leave the list alone for the future. Corky in La nursing Isabelle with a strep throat ________________________________ Message 4 _____________________________________ Time: 02:50:59 PM PST US From: "gbowen@ptialaska.net" Subject: RE: Pietenpol-List: Kevlar --> Pietenpol-List message posted by: "gbowen@ptialaska.net" I've worked a fair amount in the composites industry with Kevlar, so here's my two cents worth. 1) Don't think Kevlar is gonna give you what you're looking for in terms of accident damage to your tank over glass, especially using only a couple plies over the glass core, 2) if you impact something, that pokes a hole in your gas tank, you're gonna have a leak whether it's covered with Kevlar or not, the resin system will shatter and leak at the damage spot, 3) Kevlar is very hard to work with for two reasons, a: it cuts very difficult therefore needing the special cutting tools, so you gotta shell out the $60+ bucks, b: it has a lot more filaments per tow bundle than glass so it consumes more resin per square foot to wet these bundles out. 3) Kevlar has a tendency to separate from the glass plies. The composites shop folks at Lufthansa used to get new 737/747 engine cowlings from their supplier in the US that had a Kevlar inter-ply to prevent jet engine vanes from shooting thru the cowling into the fuselage. I watched them remove the Kevlar ply, just like peel ply, and toss it away, because subsequent repairs to the cowling wouldn't stick. Kevlar has a couple nice advantages, a) stronger than fiberglass or carbon, b) lighter than either one. Gordon Bowen Original Message: ----------------- From: Pilots4ETW@wmconnect.com Subject: Pietenpol-List: Kevlar I'm thinking of putting a couple layers of Kevlar on the fuselage tank I'm building to offer more safety over a simple fiberglass tank. I read in the Wicks catalog that Kevlar is 2.5 times stronger than E glass, and 10 times stronger than aluminum on a specific tensile strength basis. The problem is I don't want to invest in a pair of $60 scissors that will probably be used one time. Does anybody have any experience in cutting Kevlar with a regular pair of scissors or is there an alternative to the $60 version? Roy ________________________________ Message 5 _____________________________________ Time: 09:11:59 PM PST US From: Rcaprd@aol.com Subject: Re: Pietenpol-List: Kevlar In a message dated 3/11/2005 5:15:56 AM Central Standard Time, Pilots4ETW@wmconnect.com writes: I'm thinking of putting a couple layers of Kevlar on the fuselage tank I'm building to offer more safety over a simple fiberglass tank. I read in the Wicks catalog that Kevlar is 2.5 times stronger than E glass, and 10 times stronger than aluminum on a specific tensile strength basis. The problem is I don't want to invest in a pair of $60 scissors that will probably be used one time. Does anybody have any experience in cutting Kevlar with a regular pair of scissors or is there an alternative to the $60 version? Roy & Sterling, I agree with Gordon. I don't think the effort to use Kevlar in with the lay-ups of Fiberglass is worth it. Kevlar is the most abrasion resistant material of all the composite materials...that's why it's used in bullet proof vests. It is a LOT more expensive, hard to cut, difficult to wet out. You're trying to build 'Crashworthyness' into your plane...much better to build 'Airworthyness' into it. There are two types of Fiberglass: E-glass is used where electrical resistance is the requirement, and S-glass is used when strength is the requirement. Of all the composite materials, Carbon Fiber is the strongest in compression, but offers poorest in abrasion resistance, therefore each type of material has it's place in a given design, in addition to the type of resin. I used Omni-direction Kevlar on the leading edge (about 1/2" wide), for 'tipping material', on the 3 props that I've built, because of it's abrasion resistance. Then wrapped the entire blade with one layer of the light weight fiberglass, all the way to the root. I used Polyester Resin (auto body stuff) on the props. Epoxy Resin, such as the 'West System', is the preferred type of resin for fuel, oil, and chemical resistant applications. Chuck G.