Best Resin for Fabricating Diffuser

[sidney]

Wondering what folks use to fabricate the diffuser. I'm getting ready to lay-up one for the Tatuus, and need advice. Obviously, resistance to temperature is important, since the exhaust will be running along one of the "ramps." TIA for any input.

[carnut169]

IMHO, buy one that works. Gyrodynamics diffusers are not terribly expensive, are light, and work very well. Mike will also add Kevlar or nomex if you'd like some added protection.

Save yourself the time and trouble!

[sidney]

IMHO, buy one that works. Gyrodynamics diffusers are not terribly expensive, are light, and work very well. Mike will also add Kevlar or nomex if you'd like some added protection.

Save yourself the time and trouble!

I would if I could, but the issue is that the center section of the diffuser would have to be heavily modified. I've talked to Mike B. about my changes, and they are significant enough to require a different diffuser design.

[Matt Conrad]

We only use epoxy resins and have had good luck with the West Systems products. There may be others that are better, but these products are very user friendy and can be found at all West Marine stores (and online) and they have a pump system that works very well to assure proper mixing ratios.

FYI...our diffusers are vacuum bagged and consist of four layers of 7725 Glass (8 oz.) and a 1/4" foam core for added stiffness. The weight is approximately 11 pounds after paint.

Here's a picture of one "under the bag"...

We lay up the entire floor in one piece and then cut the side panels off and build the attachment flanges seperately.

Matt Conrad
Phoenix Race Works, LLC

[Brian]

I use West System epoxies too. They have quite a range of fillers that you can add for various things, and the pump system is just about fool proof. I do use polyester for quick work on stuff that isn't structural in anyway. Polyester isn't compatible with foam cores, though.

Brian

[HazelNut]

west systems is great stuff!

[Mike B]

Ian,
As stated before, the West System is a great compromise between strength/cost and ease of use. The 7725 glass is also a good compromise between cost and strength. The West System should be available at most any boat dealer although I don't know that you'll have many in Iowa... . If not, www.wicksaircraft.com has pretty good pricing but you'll have to pay shipping.
You owe it to yourself to give Joel at AVT (www.avtcomposites.com) a call at 317-546-6840. He's a racer, is up to speed on F1000, and always offers great advice. He has some of the best prices on 7725. He also has a 6781 S-glass for just a few bucks more per yard. S-glass gives you near-carbon strength for a fraction of the cost. He also has a Shell resin that is a bit cheaper than West and offers higher heat resistance but you need to be more conscientious when mixing it. Good luck with the project!

Let me know what you want to do about the diffs.

[preform resources]

Yeah ,this has been good advice,epoxy systems with any reinforcement give superior physical properties compared to poly or vinyl ester systems,they cost more but the end result is worth it. vacuum bag and use some heat(ceramic heaters) to help cure your parts you don't need a lot of heat 125 F will go a long way to improving the physicals of your job but most hi temp room cure resins will give you adequate physicals at the factory predicated temps ,usually 77 f or so.
Dave Craddock

[sidney]

Ian,

Let me know what you want to do about the diffs.

PM you about the diffs. Thanks for the advice. There is a West Systems boat guy in Des Moines. I'll be paying him a visit soon. Thanks to everybody for thier input.

[RobLav]

Agree the West system is easy because of the pumps. They really do work great.

Lately, I've been using some old Aeropoxy I had bought about 7 years ago. No worries about shelf life since it hardens real well after putting the mixed stuff in the microwave!

[rcrockett69]

We used the West Systems for our undertray and diffuser as well. If you are looking to gel coat the diffuser there is an expoxy resing that actually will work with polyester resins for layup, System 3. We have used this exposy resin on gel coated surfaces without the risk of shrinking during layup. Also to protect the epoxy from the exhaust heat I used a self adhesive reflective heat shield that is applied right under the exhaust and engine area that is close to the undertray and diffuser.

http://www.heatshieldproducts.com/

[Steve Demeter]

Epoxy from Aircraft Spruce.

Remember that if you use polyester, nothing worth a darn will stick to it in case a repair is needed.

A trick my friend who is into experimental aircraft taught me : If you want a smooth finish without the weight cost and time of gel coat, cover the surfaces with wax paper (the kind used to wrap food in) after you lay it up.

After it hardens, peel it off and near perfectly smooth surface without all the hassles of gelcoat.

[John Robinson II]

Very Cool idea, Steve. I was told about using wax paper to mold from but not to lay over top to smooth.

Thanks Steve and Apex!

John