RICMOD5634

Why do builders fiberglass models? I,ve built lots of kits all the way up tp 1.20 size, and sheeted wings and fuse. , which adds weight. So why do they then fiberglass over this and add more wt.? Kits are getting harder to find these days and I'm thinking of getting plans and having a kit cut 1/5 or 1/4 size. ARF's have their purpose I guess, their quick and light, but there is nothing personal in them.
Fiberglass

Does it have something to do with scale?
Is it added strength that's needed in bigger planes?

Whould really like some insight into this!

Thanks, Rich

ByLoudDesign

In some cases it is a very quick and easy way to put out multiples of a very scaled detailed A/C. If you skin light it is a good way to add strength and ruggedness. It is easy to pop a hole when handling heavy A/C in fibric or thin balsa. When you talk about ARF and RTF it is all about cheap mass production!

Harley Condra

My Feedback: (4)

A good paint job cannot be acomplished without first filling and sealing the balsa grain. Lightweight glass cloth and polyester or epoxy resin does a great job of sealing the grain. It also adds a hard shell to the balsa, which will help stop some of the inevitable hangar rash, and provides a suitable, compatible surface for primer and paint adhesion.

Ap properly done glass and paint job is well worth the weight gain, but if done incorrectly it will add a ton of weight and turn the airplane into a slug.

Harley Condra
BVM REP
JetCat REP

Ed Smith

Not easy to answer in a short post.

I am a firm believer in the use of fibreglass in it's many variations. A lot of the kits (Not ARFs) come with plastic parts. These parts are horrible. Eventualy the plastic will crack, the paint will peel off, etc, etc. Plastic wheel pants on a grass field, forget it. Once the plastic parts fall apart what is one to do, buy more and start again. There is a fair amount of work required to to finish the plastic parts to suit the finished airplane. The amount of extra work to make molds and subsequently glass parts is not that prohibitive. The pictures shows a glass cowl and wheelpants for a Goldberg Super Chipmunk kit made from the plastic originals. As an aside I have sold a couple of sets and I am now ahead of the game. So with fibregass, repeatability is easy.

I Pylon Race. The rate of attrition is fairly high. I can mold up a new fuselage and have a new airplane in a couple of weeks.

For finishing, On a balsa surface a lightweight cloth/resin surface provides a hard surface for subsequent painting.

I am currently building a Top Flight P40. The picture shows the plastic original part for the top airscoop, the mold and the glass part. It also shows the plastic LG fairings and the cowl primed ready for final finishing and subsequent molding.

This is the shortest answer I can give you.

Ed S

RICMOD5634

I Guess I am seeing the light. On kits that called for 1/16 sheeting I learded to go 3/32, but you still had to be a little carefull picking them up. Where glass would make it stiffer. I agree the plastic parts are really cheap.

Thanks for the info: Rich

John Sohm

My Feedback: (9)

Not only that but did you ever see a balsa plane that just had paint applied over the wood? Over time, due to the wood absorbing moisture from the air and then drying and repeating that for many cycles, the wood tends to check or split. The fiberglass tends to bind the grain of the balsa together and prevents that. It gives it a really tough surface and if done correctly, donsn't add much more weight than plastic covering. Monokote, if I'm not mistaken, weighs about 1.8 oz./sq.yd. If you use .6 or .75 oz. fiberglass, you can add over an oz. of resin per sq. yd and still come out the same. But you won't add that much because once you lay down the resin, you're going to squeegy off about a 1/4 to 1/3 or so of what you put on. Add the primer which is just to fill the grain, most is sanded off and then shoot the paint on and you will probably come out just a bit over the plastic covering and have a much more durable plane to boot. That's why we fiberglass.

saramos

I fiberglass because I just can't get this type of finish with any of the plastic coverings on the market.

Soctt

SCALECRAFT

My Feedback: (13)

Or like some of Ed Smith's and my models, we get rid of the wood and use composites to fabricate the model.

For me, full composite construction done right is the most durable without weight gain, no hanger rash and no dings, and at times even lighter than balsa. Also, composite models offer far more room in the fuse and wings to work with.

Steve

PJ_TankPilot

I have used fiberglass cloth over wood for years and it works great when painting.

However, I have not found a technique that works well for applying shrink film covering over a glassed surface. I can get a really nice finish until the plane sets in the sun. Then I have bubbles with no way for the air to get out.

How do you guys cover glassed surfaces with shrink film ?

Ed Smith

I do not. I do not try to cover over the plastic parts that come with some kits either. I always paint.

Ed S