Using Polyurethane Foam to Modify Fiberglass Aircraft Parts

Liquid polyurethane foam is an easy to use material for repairing and modifying fiberglass parts on homebuilt aircraft (engine cowls, wheel pants, fairings, etc) This video demonstrates how this foam can be used to modify the shape of an existing engine cowl in order to fit a new engine. The same principle can be used for repairs and modifications of any fiberglass part requiring similar changes.
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[@johnpiper82]

St mask should be used when sanding. Urethane dust in your lungs will not dissolve , you will have it for the rest of your life. It takes 24 hours for urethane systems to fully cure. Ratio of materials should be done by weight using a very good scale. When the material is cured, a brittle product means you had to much “A” side or isocyanate. If the product is soft or spongy you had to much “B” side or resin. Just a couple of tips I was in the polyurethane business for 40 years.

[@rogangranite]

Wow John I missed this one it was very good. I am an old fiberglass guy from way back this guy did a really nice job. Thank you John for all your efforts towards our sport/dreams or something like that out of the hill.

[@emrcee]

Great video...as usual. I would like to see some tips on creating fiberglass shapes for streamlining/sealing gaps between wings and fuselage.

[@JBELE051]

emrcee. Me too I wana see that one.

[@southjerseysound7340]

You can stretch speaker grill cloth over the surface, and when you're happy with the shape apply a few coats of resin. This will essentially give you the shape and from there you add your choice of fiberglass to build the actual part and depending on your needs you either build up from the top or bottom of the cloth mold. Also for less intricate shapes you can use another cloth like t shits,old sheets etc.its not a big deal since it'll be trashed. Last but least is when building over a existing part I'll coat it with peel ply,masking tape foil etc depending on what I'm doing. But for instance when I'll be making a part from the stretched cloth I'll leave the peel ply attached to it.this way you're able to separate the fabric from the actual part........if you want more information there's a lot of videos on building speaker pods and boxes etc. The methods carry over but the main difference is weight isn't as big a concern so they'll generally leave the grill cloth start in place .

[@southjerseysound7340]

Its sort of like fiberglass instead of dope on a fabric plane.the curves are created similar. So to add on to my previous post,say you want to create a smooth curved panel to cover a gap where foam won't work because you're not able to cover up there. You'll lay your tape or peel ply across,stretch the cloth across adding anything u want or need to help the shape/transition if needed ,multiple coats of resin, let cure,carefully remove and then build from that........its actually pretty easy once you have tried it.

[@EZ_shop]

Good one. Definitely more fiberglass tips, please.

[@felipefried3596]

Wow, this is just the tip I needed. Please, more tips on building components, and repairs with Fiberglass!

[@timokurki6538]

Another alternative is to use Sika Boom polyurethane foam. It comes in a spray bottle and can be applied on to target area with a nozzle. No mixing required, and it is correct consistency out the can right away.

[@KennethMHeide]

Purchase a Surform Files as it works much easier when shaping this kind of foam. When close to your shape use a flat or flexible sanding board to finish off the shape needed.

[@velocity550]

Great tip. I show your videos at our EAA chapter meetings. I would like to see how to use sheet wax.

[@TheDirtflyer]

Great presentation,thanks. Great Tip on Composite ,cowl repair/ Modification work .

[@wingsofmind]

Looks like a melted ButterScotch ice cream

[@michaelmott7402]

You need to get a cheese grater for the big parts to eliminate the large amount and then you can do it with the sanding board after especially with the two pound mix it’ll make your life easier.

[@gvrose1]

You can cut that to shape faster with an electric wire. I used that method when making remote controlled aircraft wings.

[@capskybound]

More fiberglass tips please!

[@JeffreyinChina]

I used some Home Depot expanding spray can foam - it was not the same , listen to Jan and Dont use that stuff. A video demonstrating composite layup options & comparison would be great , 'how may layers of ..." I ended up with 4 layers of carbon and one 2mm foam cloth layer...

[@fredericktrobinonsr4947]

Yes more fiberglass tips, please.

[@BuceGar]

Very cool, excellent results.

[@rb1820]

I wonder how long it will be , when the post office starts making the rest of us pay for people who take the free envelopes because somebody is always using them for other than sending something?

[@lorenwarner8631]

Should we add wax or anything to the foam to prevent the fiberglass resin from sticking to it?

[@1shARyn3]

Definitely MORE --- including suppliers of material

[@1shARyn3]

and, damn --- using a piano hinge as a saw --- VERY CLEVER!!!

[@JBELE051]

Is that a UL 350 COWL that was modified to flatten the top? Looks much better

[@nickmalone3599]

Great video

[@ikay2102]

Good to know

[@phearl3ss1]

Did you remove the foam from the nose after you applied the fiberglass? Does the fiberglass stick to the foam?

[@SuperYellowsubmarin]

Nice video. You really want to wear a respirator and gloves when pouring though, this thing is nasty !

[@aerobatgaming2033]

Is it possible to make an entire custom cowl using this technique?

[@trhacje_m2187]

Yes it is, even entire aircraft ;-) Recommend watch the Master of this work kzbin.info/www/bejne/i2OziWSmbNOVrZo

[@claykilgore7279]

More please.....

[@josiahjulin1277]

Will it cut with a hot wire?

[@jeetenzhurlollz8387]

awesome thks

[@OleDiaBole]

What a nice guy.

[@FlyValorantFly]

Or just use ramen and superglue lol

[@uptowngrafx]

Great work . I am using these techniques for my motorcycle builds. Yes, more please :)

[@oscarjonesxxx2893]

No face mask on here. Lazy or just don't care about the stuff that goes into your lungs? Both? I recommend wearing a mask whenever you sand anything. Come on, man.