Vinyl ester or epoxy for glassing?

[tildenm]

Howdy,
I designed my first scratch-built which RockSim estimates hitting mach 1.5 on a J800. I am going to try kevlar/carbon blend I think, in theory it should be a little more forgiving in fin flapping.
I have been planning on using vinyl ester resin rather than epoxy because of temperature concerns. Thoughts?
Tilden

 

[hognutz63]

I found this write up:

https://www.redrockstore.com/resin.htm

Even though it is from a boat builders perspective, it made a lot of sense to me why epoxy resins would be better than vinyl ester. You don't want something to be forgiving with fin flutter, you want something to help prevent it.

Eric

 

[tildenm]

Thanks. Found this article too which was good: https://www.catamaransailingphuket.com/EPOXY-VINYL ESTER.pdf

 

[cjl]

Epoxy will work fine, and it should be stronger. I'd use epoxy. Besides, temperature really isn't a concern until a lot higher than mach 1.5. I have used (and would recommend) Aeropoxy, West System, and Pro-Set. Of the three, Aeropoxy and Pro-Set have higher temperature resistance (180-230F instead of 120-130 for West), although for maximum benefit, you need to post cure them at high temps (for Pro-Set, the standard post cure is 8 hours at 180F).

 

[troj]

Vinyl esthers are also pretty nasty to deal with, and require proper gear to use safely.

-Kevin

 

[talkin Monkey]

Vinyl esthers are also pretty nasty to deal with, and require proper gear to use safely

Been using the Bondo stuff, pretty sticky, messy and stinky (see avatar :marshmallow: )

... Seems to work well for my uses but when the Bondo runs out I'll be getting something along the epoxy line. :2:

 

[stantonjtroy]

I've used both for many years in both marine and aviation industries. I confess I am a big fan of VE but I like West as well. Truely, it depends on the specific use. VE will wet out far better than epoxy, especially if you are using matt. VE also sands better and has more flexabality with reguard to catylization rates. This is particularly usefull if you are working in very hot or cold areas. VEs greatest plus is, depending on the promotion schedule, you can achive a broad range of strength and hardness. The two biggest hits are price, VE is expensive, and bondability. Attaching parts to a VE glassed surface with anything but VE will most likely fail. For rocketry, West is useally the best rout. From a cost, ease of use and bondability standpoint, you can't go wrong. Even though epoxy presents it's own health hazards, it is safer than having to handle MEKP.
FWIW

Troy

 

[MarkM]

I'd advocate using epoxy for your layup for all the reasons mentioned in previous threads. But, you don't need to use West System. Any good quality laminating epoxy will do the job perfectly. Stay away from the "hobby brand" laminating epoxies, however...they are not as good. I like US composites. Just as good as West and considerably cheaper. I've also used a local brand manufactured here in the Tampa area which works just as well.

 

[MarkM]

Howdy,
I designed my first scratch-built which RockSim estimates hitting mach 1.5 on a J800. I am going to try kevlar/carbon blend I think, in theory it should be a little more forgiving in fin flapping.
I have been planning on using vinyl ester resin rather than epoxy because of temperature concerns. Thoughts?
Tilden

kevlar can be difficult to wet out. It will probably take more resin to properly and completely wet out kevlar cloth than either pure carbon or pure fiberglass. I've seen some examples where there were some dry spots after curing. But, it certainly is strong when done properly. Kevlar is also extremely difficult to cut. I suggest purchasing special kevlar scissors which many places selling kevlar cloth carry; they;ll make cutting the cloth far easier.