bigfella65

Guy's had a search of the forum's but couldnt find exaclty what I was looking for, has anyone got a link to a good tuturial on how to fibreglass a firewall on a arf. I'm in the process of building a H9 spitfire and from what I've been reading the firewall need's to be reinforced. I never worked with fibreglass before so Im asking for assitance in this area, thank's.

bigtim

My Feedback: (13)

where did you read that.

first you really don't need to fiberglass the firewall, you obviously have seen the 44 pages of the H-9 Spitfire thread because I saw your posts search the thread it does have references to the firewall there in all that information.

if it was really needed there would be a huge volume of posts on the subject,of firewall failyer but there isn't.
after having problems with a couple of there models H-9 added more wood to the firewall joints of there planes several years ago.

if you insist on doing it anyway, this is what you need to do its pretty simple really.

there are several ways to do it first a description of what guys are talking about, most are using fiberglass cloth typical weight is 2oz-4oz cloth, on the light side of surfboard weight fiberglass cloth.

the resin used is mostly epoxy,since its fuel proof and strong,not polystyrene used in boats and surfboards.

as for the way to do it there are several.

1. cut back the covering at the front of the fuse, just a little bit back from the edge of the cowl where the cowl mounts on the fuse so it covers the fiberglass up wrap the cloth around the edge of the firewall to strengthen the connection point at the fuse.

2. would be to reenforce the inside of the fuse at the firewall connection, with cloth and resin where the tank is mounted this is a little harder to do since the space is limited but its doable with some patience, and a stick to position the fabric and adhesive.

3. so that being said its overkill, if your worried about strength, just warm up some epoxy,set it in some warm water for a couple of minutes the epoxy parts A and B will become runny, after mixing the 2 parts paint the fuel tank compartment with the epoxy making sure to coat the triangle stock at the firewall, the epoxy doubles as a fuel proofer in the tank area, thats really enough to strenthen the area and avoid adding extra weight.

a heat gun can also be used to heat the epoxy up after mixing it to get into all the spaces,warming the adhesive makes it flow like water.

I have 3 of the Hangar-9 planes,the P-51,P-40,and the Corsair, none have the firewall glassed there all fine, I did coat the tank area with epoxy to be sure the wood was glued well, and to fuel proof the tank area there all fine.

alan0899

G'day Mate,
I use Zpoxy finishing epoxy, it is fuel proof, thin & can be brushed on, you can add some fibreglass cloth, after you paint it on, for reinforcement.
It's great stuff & lasts for years.

bigfella65

bigtim, I read on another forum that fibreglassing the inside of the firewall was the best method to strengthen the firewall, so I assumed that would be the best route to go. I originaly was just going to epoxy the hell of of it and leave it at that.

alan0899 thats exactly what I intend to do thus why I was asking for a tut, just so I do it correctly. After I put on a coat of resin then lay the cloth on do I put on more resin over the top of the cloth ? also how many layers of cloth would I use, just the one be enough or more ?

thanks for the replies fellas.

alan0899

G'day Mate,
It depends on how much extra strength you need, but I like to make sure the cloth is filled, but not so much, that it runs.