Folks, I want to make a carbon half bypass. Not needing a full bypass and wondering if a good epoxy resin(from ACP) is sufficient or do I have to go with high temp epoxy? this is mainly meant to provide some some heat protection of areas in the fuselage/retracts/door cylinders around the engine bay and maybe catch fuel some drips. I plan to use BVM heat shield in the rear section of the bypass or maybe even the whole thing. engine is a 180.

use west systems epoxy 105 and 205 with carbon cloth.

Once you have your bypass finished you can coat the inside with BVM heatshield.

Yes West is good, made a series of carbon bypasses for a Skygate Hawk full duct conversion a few years back and worked perfect with some BVM Heatshield on the back 1/3rd.

Plug and bypass..........

marcs

I would stay away from West resin for a number of reasons, mainly due to heat and sheer strength properties. How much heat is this component going to be subject to?
West 105 has a Tg of 142F and a heat deflection temperature of 118F. If this is going to get warm at all it will not hold its shape.
Fiberglast has a high temperature resin that is good to 270F that would probably work. It is fairly easy to work with and can be post cured at atmospheric so you will not need an autoclave.

If you have any questions you can shoot me a pm.

Scott

Good question on the temps. It seems the rear section would be easily go beyond 140F given the exhaust cone of the turbine is said to glow. So it's hot.
Given I wont need much for this application, I guess there is nothing wrong with using the rest of the high temp epoxy elsewhere in other layups as you would with regular laminating resin? Is there any huge drawback to using it that way?

The only real drawbacks to using this resin system for general laminating are the fact that it is a little thicker than most unfilled resins at about 1900Cp mixed, and to get the full strength it should be post cured at an elevated temperature. Up to 300F for maximum heat resistant properties, but at 200F for maximum strength.

I'm not sure why you want to make it out of carbon fiber. While the BVM bypasses are CF, most if not all others I've worked on are actually fiberglass with some black pigment mixed into the resin. If you are going to paint it, as the mold likely won't have a polished surface, nobody will ever know the difference and you'll save some coin.

Regards,

Jim

When I made my bypasses for the SR-71, I laid them up with a high temp resin from Resin Services (586) 254-6770.
Resin HRT 212
Hardener HT 386-99

No post cure required and it is good to 325 degrees or so. From my understanding it's used by some of the NASCAR guys for some of their layup works.

I liked how the resin worked so well for that, I ended up doing the entire layup of the show plane that everyone has seen out of the same resin. Considering the skin of the black airplane gets to the low 150's in the Midwest summer heat in the sun, now I don't worry about it getting soft. Now the gear on the inside, is a different matter but I don't have to worry about the shell itself.

I used West for my molds and for the prototype, and found West's to be great to work with and very forgiving when mixing. The only 'catch' on the resin from Resin Services, is that it's got to be mixed by weight, very accurately, and very well mixed. I used a small gram scale, and you mix it by weight one part hardener to 3 parts resin.... so for a full batch, I'd pour resin into my mixing cup to 75 grams, then put in hardener until it read 100, then mix well.

It's a tiny bit thinner than West's but works great, and has a bit longer working time that West as well.

I've had probably a handful of wet starts in the bypasses with them and they are still in good shape, so I'm really pleased how it's holding up.

Lance