Veneered foam vs traditional built up construction

[Ron Gray]

Simple really, I would like to hear other people's views on the use of veneered foam construction bearing in mind the situation regarding future supplies of balsa.

The reason for this is because that whenever I mention more use of this form of construction for kits I tend to get replies implying that veneered foam is not proper building. Now, as someone who loves building (and flying) from plans or from kits I see veneered foam as just a different form of construction with many benefits, light weight, strong and accurate (assuming the foam cutting is accurate) so why the 'stigma'.

So step up with your views on this please!

[Graham Davies 3]

Good post Ron.

I think there is a lot of 'superiority' associated with arguments against foam.

I love building, and don't have the facilities to cut foam, so generally build my wings, but I would have NO HESITATION using foam wings, decks or anything else. My Warbirds Replicas Tempest has both foam wings and decks, weighs very little, is straight and true and flies brilliantly. So what's not to like?

The inbuilt shock absorbing properties have also meant my undercarriage blocks are still solid after some 'enthusiastic' landings.

I shall use whatever is most appropriate to the model and situation at the time!

Graham

[Edgeflyer]

I agree. Veneered foam has been around long enough to be almost traditional! Ive found these wings take more punishment than built up wings. There is a tendency for the veneer to lift. Fibreglass coating avoids that.

[leccyflyer]

Life is too short to get worried about what goes into a model aeroplane - I have built up wings, veneered foam wings, hot wire cut EPP wings, injection moulded foam wings, depron wings, glassfibre moulded wings, Correx wings and guess what, they all fly.

If someone tells you that any particular bit of building technique that you use to put your toy aeroplanes into the sky is not traditional building, ask them to give you a tour of their balsa plantation, castor oil plants and silkwork farm.

[J D 8]

The old brown paper over foam core still a valid build method. Did a 70 inch span wing this way with a top coat of Solartex. Tough as them old boots.

[Peter Christy]

Horses for courses, really. There is something about an open structure, nylon covered wing that is just "right" for something like a Jackdaw or Super 60. But taking my KingPin as an example, it has a sheet covered, built-up wing! Looking at it, it is impossible to tell if it is "traditional" structure or foam cored!

A lot of sport and aerobatic models fall into that latter category!

I do have a bow somewhere for cutting foam cores, but getting the polystyrene foam blocks seems to be problematic these days. Anyone know of a good source?

A lot of the models I built in the late 60s used foam cores produced by a local modeller, and covered in sheet balsa, which didn't lift like veneer can. But that rather defeats the object!

In short, I have no problem whatsoever with foam cores, but would probably wince if I saw an "old timer" using them!

--

Pete

[Former Member]

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[Allan Bennett]

One advantage of foam over traditional built-up wings can be noise reduction. I first replaced the plastic wings on my Kyosho Learjet with built-up balsa wings when I wanted to add retracts, but later I got a pair of foam core wings made for it (can't remember what prompted me to do that) and the reduction in whine is amazing.

[Former Member]

[This posting has been removed]

[kc]

Some items other than wings can easily be made out of foam shaped with just glasspaper ( must be NEW coarse glasspaper not used ) and covered with veneer or brown paper and PVA. Top deck etc etc can be made that way and replace a balsa structure.

I reckon tailplane and rudder that would normally be made of 1/4 balsa could well be made with 1/4 foam ( ceiling tile stuff?) veneered both sides. Would still need some balsa for LE & TE plus tips unless someone has a substitute light material. Unobtaniatimber??

A forum member now sadly deleted from the forum ( please come back!) once explained how he used B&Q flooring material foam reinforced with small amounts of 1/64 ply in crucial areas to make fuselages. The original details were deleted from the forum but it would be nice if someone could post some similar techniques now.

One way of obtaining balsa is to re-cycle crashed planes instead of trashing them and burning, A broken wing spar might provide enough LE & TE material for a tailplane or two. A broken tailplane half might provide material for a fin or rudder. Fuselage sides might cut down into fuslage top and bottom crossgrain material in a new plane with lightply fuselage sides. All the non-oilsoaked balsa might be reused somewhere in a new model if only as small parts. Of course Proper Aeromodellers would repair the model but the current crop of ARTF pilots just scrap crashed planes - we need to grab any balsa and recycle........

[Former Member]

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[Robin Colbourne]

Ron, Don't listen to the naysayers. Its your hobby to pursue exactly how you like. If our predecessors had listened to them we would all still be flying oiled silk and bamboo A-frame pushers with rubber motors.

If you are going to work with foam, I strongly recommend getting Dave Thomas's book 'Radio Control Foam Modelling'. There are two editions, one with a blue and yellow PT-19 on the front, the other with a PSS Pucara.
It covers all sorts from the basics of bows and foam selection to advanced stuff including cutting elliptical wings.
You won't regret getting it.

Edited By Robin Colbourne on 03/10/2020 12:41:09

[Peter Miller]

I have had foam wings in the past. I have even designed a model that incorporated foam wings. (Montezumas Revenge)

My main reason for not liking them is that they tend to be much heavier that my built up wings and I hate excess weight.

[Robin Colbourne]

Here's the other edition:

[kc]

Foam wings can be completely covered in veneer or can be partly veneered as in Avicraft Moronic, Frantic & Panic etc ( original version perhaps not the latest ones) . By just veneering the centre section and the 'D box' area, then putting capstrips along to the TE veneer strip probably saves a lot of weight of glue and veneer. Also saves on the cost of veneer and Copydex! Worth considering. Once covered it gives the appearance of a built up wing.

For some reason in the USA they have always used balsa on foam wings instead of veneer.

[Eric Robson]

Purists look away I was half way through a CAP Gladiator build when my Hawk Moth crashed not to bad the foam wings were fine, the fuselage was oil contaminated so I looked at modifying the wings. The top one was swept back so I cut it in half made a built up balsa centre section with ply spars let into the foam. round tips were added to all wings the span came out correct the chord was about 12mm oversize. it flew well on an S.C. 60 TS. The wings had strips of paper to simulate ribs and Solartex covering . The lower picture was as built the warpaint was added as a whim. I am all for foam veneer and recycling balsa anything to keep the hobby alive it has kept me happy for over 70 years now.

[leccyflyer]

Personally I think balsa gives a nicer surface on hot wire cut foam wings and possibly stands up to storage a bit better. I have had a number of veneered foam wings on which the veneer has lifted and split - not something that I've seen with balsa skinned wings.

[Ron Gray]

@Peter - interesting in your comment about lightness. I guess that it maybe your designs that mean the wings come out lighter as the recent ‘planes that I’ve built using veneered foam wings (ExtraWot, LA-7, BF110) all have extremely light and incredibly strong wings. When I compared the weight of the LA-7 wing to a similar size built up one (H9 Mustang) the veneered foam one was considerably lighter (and probably a lot more accurate). Maybe also it’s when you get to ‘planes over 50” that the veneered foam weight advantage (perceived, by me) starts to kick in?

I see quite a bit of talk on here about the need to back the home grown model industry by encouraging more people to build their own rather than go down the ARTF route and I see that an easier route for a first build would be something that has a high veneered foam content. In particular, a lot of ‘newbies’ want a scale model, a well designed VF one could almost guarantee good flying characteristics ‘out of the box’, take my LA-7 as an example, it was a very quick build and on its first flight required no real trimming and flew superbly, none of that was down to my build skills but was due to a very good design by Richard Wills. My CF Extra Wot was similar, a very quick build and again required little trimming. Sure, I’ve played around with the trimming of the XW since but that’s just me tuning it to suit my flying style.

[Eric Robson]

Posted by leccyflyer on 03/10/2020 13:08:25:

Personally I think balsa gives a nicer surface on hot wire cut foam wings and possibly stands up to storage a bit better. I have had a number of veneered foam wings on which the veneer has lifted and split - not something that I've seen with balsa skinned wings.

The current problem Brian is the shortage of balsa. I have used this method and do prefer it but if it becomes scarce then alternatives need to be found.

[ron evans]

kc ,My plank on a box hack was done this way, but with balsa stuck on with double sided tape ,and a little white glue.

Hasn't fallen apart yet and would probably work with veneer too.

Done a couple of flat sheet wings with B&Q 6mm floormate, covered with glass and Wilco poly...tough as old boots and long lasting.

[Bob Cotsford]

If you are into the building part of the hobby then a 'traditional' built up structure is the only way to go, much more involving and the sense of satisfaction from standing in a pile of shavings and sanding dust whilst admiring the sleek curves of your planked and carved structure is hard to beat.

On the other hand if you want to build a resilient airframe without all the sweat and tears then veneered foam is hard to beat. It's still mostly all your own work and there need be no weight penalty over a built up structure unless you compare it with a minimalist vintage stick and tissue design. I'd challenge anyone to build a wing of equal strength but lower weight compared to the foam wing in my old kit build Acrowot or the Billkits wing that replaced it after 20 or so years of abuse.

It's just two different takes on the hobby, do you want to invest time and develop your building skills creating a work of art or do you want to build a practical flying machine and fly it?

Edited By Bob Cotsford on 03/10/2020 13:55:29

[Ron Gray]

Fair points Bob, but I do see VF as the ‘best’ way to get newbies into building.

[Mike T]

Posted by Allan Bennett on 03/10/2020 11:48:27:

One advantage of foam over traditional built-up wings can be noise reduction. I first replaced the plastic wings on my Kyosho Learjet with built-up balsa wings when I wanted to add retracts, but later I got a pair of foam core wings made for it (can't remember what prompted me to do that) and the reduction in whine is amazing.

My new Precedent Funfly (built-up wing) is considerably noisier than the one it replaced (foam wing). I habitually picked the old one up by wrapping my free hand around the leading edge. When I did this with the new one, my fingers split the sheeting - so superior point loading is another advantage for foam!

That said it all depends on the foam. I had one kit with foam so soft and spongy that handling the wing panels inevitably resulted in surface deformations. On a current project (yet to fly) I'm concerned that the wing is so heavy it won't lift it's own weight. The best foam wings I've seen came with the ATS Kite kit - superb in all respects.

[Bob Cotsford]

Posted by Ron Gray on 03/10/2020 15:36:40:

Fair points Bob, but I do see VF as the ‘best’ way to get newbies into building.

No argument from me Ron, complex built up structures won't engage many newbies' interest for long and there's a high probability the build will stall. Box fuselage, foam wings and maybe foam decks to improve the looks makes for a gentle introduction to the building side of the hobby with maximum chance for success.

[Mike T]

Posted by Bob Cotsford on 03/10/2020 13:51:59:

It's just two different takes on the hobby, do you want to invest time and develop your building skills creating a work of art or do you want to build a practical flying machine and fly it?

As a long-term project, I'm currently investing time and developing my building skills on a 1/5 scale Spitfire with an epoxy/glass fuselage and foam wings. Time will tell if it becomes a work of art.

As a diversion, I put together a quick-build practical flying machine - the aforementioned Funfly which is all built-up balsa and lite-ply.

There are no 'different takes' in my workshop...