Composite wings, any advantage ?
 

Hi all
I want to state the following, and my question is; do you agree :
Compostite wings for F3A models is only about finish and low effort to get model ready for use. I have yet to see any kit that comes with composite wings that are even close to the light weight possible with balsa build-up or sheeted foam core wings. Eaxample : my Gaudius came with composite wings that with servo is about 450g (15.8 oz) per half, my own foam-core, balsa-sheeted, Monocote covered wings are about 390g (13.7) with servo. Typical kit-weights from other suppliers are 400-450g per half without servo, cables, and control HW.
Light wings are an advantage in every respect, starting and stopping roll movements, stopping spins and snaps etc. all is better with lighter wings.
Why is it then that most new models available come with composite wings, are we really that lazy ?

Ola

RE: Composite wings, any advantage ?
 

define your understanding of "composite" please because a Foam core wing sheeted with Balsa and covered with light glass and resin is also a "composite" structure.

RE: Composite wings, any advantage ?
 

Ola,

I agree lighter is better, and in truth, I believe you are correct in that laziness is big factor.

The planes I am currently flying have full composite wings that are much higher quality than I could build and have fully sealed aileron (and elevator) hingelines that can not be matched with foam/balsa construction. From my experience, the foam/balsa wings will become more flexible as they age....the foam becomes softer, and the beads lose adhesive to each other. At some point, the wings will need to be replaced (500 - 1500 flights depending on initial build quality and weight). I've not noticed any change in the strength of composite panels with 1500+ flights.

For the 3 Wistmodels Bravos I have built (2 for me, 1 for my Dad), average wing panel weight with servo is 405 grams RTF (including attachment nuts) for painted full composite wing panels. For that small 30 gram penalty, I'm quite happy to have the added longevity and never need to touch up the monokote. It would seem the challenge is for other manufacturers to attain the lightweight composite panels Wistmodel has been making for several years.

Regards,

RE: Composite wings, any advantage ?
 

My experience is the same as yours. I prefer balsa sheeted foam because of the lighter weight and because it's what I'm set up for.

Unfortunately, we are almost fully into an ARF world and modelers that can actually build an airplane are becoming rare. I'm not so sure that it's a matter of laziness rather than convenence in our busy lives. It's a sad trend in my opinion. Here in the USA, local hobby shops rarely stock contest balsa because nobody seems to want or need it anymore. I don't blame the manufacturers for this. They're simply supplying what's being demanded. As a builder, I'm finding less and less kits that fit what I want. I have no answers here, just opinions.

Verne Koester

RE: Composite wings, any advantage ?
 

I had the chance to (very gently!) handle and inspect one of the wings of Ken Velez' Bravo and these have got to be the cutting egde in pattern wing design and construction. Very light, strong and true.

I have no doubts about their strength having seen a fair number of Dave's snap rolls, which are of the very aggressive nature with a clear elevator break and not the somewhat questionable 'flick rolls' that are common these days. I would guess that some of Dave's Bravo wings have endured perhaps 8 to 10 thousand such snaps.

RE: Composite wings, any advantage ?
 

Hi Ola,

I think the main advantages of composite wings is consistency of finished product due to a mold being used and paint finish i.e. no steps in paint lines. Most fuses are molded for consistency and complex shapes.

Weight is a penalty but composite wings are getting lighter.

Regards,
Jason.

RE: Composite wings, any advantage ?
 

Hello Ola,

In general I think that lighter wings must be better for the reasons mentioned in your post. That said, I know of one very well respected international class F3A pilot who is alleged to add ballast to his wing tips to make the model more stable in turbulent conditions!

My Gaudius wings are a little lighter than yours – around 370 grms bare weight and 440 grms with a JR DS8401 servo and MK ball-raced fittings. Posted weights for a Spark EVO are also around 375 grms bare weight. For comparison, the bare weights of the wings on my Wind S Pro (built up balsa rather than foam) are also around 370 grms - 390 grams including fences. (The Wind S wings are also considerably thinner in section than the Gaudius.)

It is interesting to note that Andrew Jesky achieved 3rd place in Muncie with a Spark (which I assume was fitted with composite wings) with many observers commenting that Andrew’s snaps were the cleanest and most impressive in the competition. There may have been other highly placed fully composite aircraft in the finals that I’m not aware of.

One other point worth making is that many composite wings are top hinged. Some pilots would claim that aircraft with top hinged wings do not roll as axially as those with centre hinged wings. I can only say that I have found the rolling characteristics of my Gaudius to be first class and certainly on par with my Wind S Pro which is noted for its excellent rolling abilities. Indeed overall, I have found my fully composite Gaudius to be an outstanding aeroplane. If I was to find fault, unless a fairly fast rotation rate is dialled in, it can sometimes be a bit slow to change direction in spins such as those in P11 and P13. In theory – and perhaps in practice also - this is something that a lighter wing should help with.

F3A is all about incremental improvement and in that sense it is difficult to argue against the case for lighter wings. However as things stand, I would agree with Dave Lockhart when he says that for most pilots, the very small additional weight of high quality composite wings is more than compensated by the added longevity and lack of maintenance.

Bob Wasson

UK

RE: Composite wings, any advantage ?
 

OK Iam assuming that composite = Carbon fibre/kevlar skins and hollow?or foam cored?
Sheeted = Foam core with balsa sheeting and glass or film covering
buolt up weel thats obvious.

foam core can be just as consistent as moulded composite wings because foam core/balsa sheeted can alsobe produced in a mould. You may not want to but too reduce voids and keep resin useage down it can be preformd and then bonded in a mould (although a vacuum bag technique is more commonly used.

I believe an advantage to a composite wing is that it can be built lighter at the tips where the wing sees less bending stresses. It can also argueable be built stiffer but I don;t see an advantage here because stiff enough is stiff enough. A wing that islighter at teh tips will allow for a lower roll ineria resulting in faster and more precise snap rolls.

However that can be overcome with faster servo's or a slightly larger control surface.

Ultimately the difference is not so much in the material but in the overall design

RE: Composite wings, any advantage ?
 

A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, "wood flies better!"

Anders J

RE: Composite wings, any advantage ?
 

Hello

I totaly aggree with Anders.
I built foam wings and built up wood wings with same dimensions and tested on the same plane Harmonie.
Rolling and snap are better with built up wood wings.
Claude

RE: Composite wings, any advantage ?
 

Hi Ola,

2 kids + demanding job = no time!

No more building for me, either pay to get built, or full composite!

I think the time saving is the biggest advantage. As long as the wings are <450g RTF I don't see a problem with them.

RE: Composite wings, any advantage ?
 

And i do believe the Spark that Mr. Jesky was flying had Dave Snow built up wood wings. Not the factory composite. I've been wrong before though.

RE: Composite wings, any advantage ?
 

Molded structure offers a time savings and repeatability of parts as the advantage to the buyer.

RE: Composite wings, any advantage ?
 

Andrew was flying built up wings and not the stock composite ones

RE: Composite wings, any advantage ?
 

In the Osiris video AJ says the Spark wings are built-up balsa because they're lighter.

RE: Composite wings, any advantage ?
 

If your foam wings are coming apart your not building foam wings correctly. My first Partner with foam wings had over 1000 flights on it and the wings were like new. The Onas I am flying now has about 700 flights with no problems with the wings. I also have to agree that top hinged surfaces at least on the ailerons are not the best. You can make them work OK but center hinging will roll better. It's also pretty easy to seal any hingeline. The composite wings Chip is producing seem a good way to go but I have yet to fly one.

I can see why manufacturers want to develop composite wings. It's very difficult to obtain the right balsa to make a proper wood wing.

RE: Composite wings, any advantage ?
 

Agreed.....My Temptress balsa covered foam wings were built 8 1/2 years ago and are approaching 2000 flights, all either on glow or gasoline. Weights are low (around 13 1/2 ozs each for 500 squares par panel) and are fully painted. I hate monokote. Silkspan and dope finishes are just as light when done right, maybe even a tad lighter than MK or UK

To Ola's first comments, my light wings make for spritely performance throughout the flight envelope. On the design question, this wing design will do everything one wants including slow snaps or Dave L lightning fast snaps, and everything in between. Just a matter of set-up. Oh and they don't require 20 degrees of elevator throw for proper snaps and spins, but that's airframe design not just wing design

Center hinging is definitely better, more balanced, at least to me. There could be other factors affecting rolling results tho.

To Ola's original comments, foam composite versus molded composite, it depends.......to me foam/balsa composite is easier to build overall and is easier to control weight. And if you want to use 1/2 - 3/4 mm contest grade sheeting, the finished composite structure can be made strong and stiff with carbon veil. My holy grail of wing construction is a fully painted, 500 square inch panel whose RTF weight is less than 11 ounces. I think it's doable with either foam or built up construction

However, the final word has not been written on molded composite wing construction. An 11 ounce final weight RTF should be a little easier to actually build than the conventional technique. Molded wing makers are just not doing enough creative things with their lay-up. My 2 1/2 cents

RE: Composite wings, any advantage ?
 

Geez....I think my snaps are slow and ponderous compared to AJ and Chip.... :D

My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.

For my own planes, I've built several (foam/balsa) that hit 1000+ flights with no discernible structural degradation. The pair of EMCs I built ~2000 were flown as primary (probably 1600 flights when it died) and backup (~50 flights). Both were solid in trim in all conditions, and both flew extremely well. However, later in its life, the elevator feel was softer on the primary on snap entries and very aggressive square corners (more aggressive than I'd fly in competition) - I'm quite certain it was spanwise flex, and I'd have never noticed if I didn't have 2 identical planes to fly back to back.

Other considerations are glow vs electric, and relative youth of composite wings in F3A - there will never be as many flights with glow on composite wings as foam given the trends towards more electrics and more composite wings.

Regards,

RE: Composite wings, any advantage ?
 

Fyi,
I just got a set of CA/Chip's wings: 394/406 gms.
This is painted, no hinges, no servo, or hardware except for the nylon wing attach nut. (no sfgs)
Dan

RE: Composite wings, any advantage ?
 

To me there is one overriding advantage to composite wings. Before you spend any time working on the wings, you can determine if you will end up with straight wings with perfect hinging and matching leading edge radii, symmetrical wing tips, etc.

A secondary advantage is they will take more abuse as far as denting. Monokote over balsa isn't very rugged and doesn't look as good.

There is no advantage if you crash and burn.

Jim

RE: Composite wings, any advantage ?
 

Another advantage for Composite wings and fuse: always look new.

RE: Composite wings, any advantage ?
 

My nine year old Partner wings and stabs look brand new.

RE: Composite wings, any advantage ?
 

agreed. They're not using the lightest cloth carbon or kevlar and also the moulding techniques probably could be better. I've not seen any fuselage or wings moulded using the Resin Transfer Moulding technique. Fewer voids and less resin usage results in a lighter structure. It probably a simple numbers game. Not enough demand for high end pattern planes results in mould sbeing designed for small production runs. Small production runs means not usage of te high end carbons like Torayca PAN based carbon fibre.
Ultimately a moulded Carbon kevlar wing should come out lighter than foam core balse sheet wing

RE: Composite wings, any advantage ?
 

The lightest carbon cloth available weights 60 gr/sqm. and is too heavy for a wing sandwich application, where we already use the lightest glass cloth available (27 gr./sqm). The only thing that can be made is in the control of resin distribution.
Resin infusion is not suitable for a sandwich laminate (balsa or herex would be soaked by the resin).

RE: Composite wings, any advantage ?
 

why do you  say it is not suitable for a sandwich laminate? There are many monocoque structures using the process.
I would like to understand your comment in greater depth .