Curare EP Resurrection

PhilF51 wrote: Thanks Mike and Alan. Why would gross grain be an issue, possibly harder cut? Once decided on wood needed I can order some in.

Depends on how long a piece you want to cut and where you want strength vs flexibility. For a fuselage side piece I would want the grain of the ply running nose to tail rather than up and down

Perhaps I'm being stupid, but cross grain makes no sense whatsoever. All ply is cross grain isn't it?

MikeSeale wrote: Perhaps I'm being stupid, but cross grain makes no sense whatsoever. All ply is cross grain isn't it?

Depends whether it's supplied as a square sheet or rectangular

It looks as if SLEC supply their ply with the outer grain running across the width of the sheet rather than the length. I've no idea why, but I guess thats why they refer to it as cross grain. I would normally expect the grain to run along the length.

OOPS (blush) I looked at the special offers page by mistake- Phil Ignore everything I've said.

Maybe I misinterpreted the word "cross grain". To me, if you have multiple layers of wood for maximum strength you would glue them alternately at say 90 degrees.

Yes! I would have the grain of any wood for a fuselage laying from nose to tail for maximum strength longitudinally. The formers would cancel out the flex vertically.

PhilF51 wrote: Maybe I misinterpreted the word "cross grain". To me, if you have multiple layers of wood for maximum strength you would glue them alternately at say 90 degrees.

Yes! I would have the grain of any wood for a fuselage laying from nose to tail for maximum strength longitudinally. The formers would cancel out the flex vertically.

Due to my failure to control a mouse I've only added confusion to this thread. Humble apologies Phil.

I cannot believe that only a few stringers and the skin are holding this thing together between those formers. The only thing stopping the fuselage breaking away completely was the thick covering film and the snakes.

Looking at kits of classic patterns generally the fuselage sides are continuous ply. There is lightening and there is lightening! Kits tend to be a bit over built I have noticed but at least when you build it you know where the strength lies. Wished I had the experience to build

Monday will order some ply, sheet balsa and balsa strips

PhilF51 wrote: Wished I had the experience to build

You'll get that by doing it Phil. It sounds to me like you're making a good start. Hopefully you'll find the experience and end result satisfying enough to keep going.

PhilF51 wrote: Looking at kits of classic patterns generally the fuselage sides are continuous ply. .... Wished I had the experience to build

Phil I'm far from an expert but all the Classic Pattern Planes I've looked at have a 2mm ply doubler that goes from the firewall to the trailing edge of the main wing, the fuselage sides are balsa. The curare is slightly different in that the doubler starts at the fire wall and only goes to the leading edge of the wing.

As for building, the Atlas is my first plane and thanks to the help I've had, I've been able to make a reasonable stab at it. It just take time and sometimes a bit of thinking things through, but it's not that complicated, well not so far. If you want to give building a go why not try the Kosmo Kit for £110

Chris - I can see why some would prefer, if they are capable and confident enough, to build their own stuff sometimes. Making your own mods, strengthening, etc is easy at the assembly stage. Checking a few of my ARFs and found that many have no continuous ply fuselage sides! Wings have balsa ribs! Ply ribs would have added virtually no weight at all. Nothing I can do about it but moan.. :lol:

Moving on, I am making a building jig when the bits arrive from SLEC, to support the Curare fuselage whilst I repair it. Gonna be fun.

In the meantime I have had a go at the wing which is relatively easy. Glued the wingtip back on and cut away the adjacent broken balsa rib. The wing leading edge has a very small solid forward edge and the rest of the profile is made up by the ribs and sheet balsa. Light but avoid crashing/bumping into anything, it will fold in. :whistle:

I have a selection of balsa sheet, tri-stock and profiles which came yesterday from SLEC. I am going to drop in a solid piece of leading edge profile which is virtually near to the wing profile. Sand down and rebate the back edges for new wing sheet to drop in.

PhilF51 wrote: Checking a few of my ARFs and found that many have no continuous ply fuselage sides! Wings have balsa ribs! Ply ribs would have added virtually no weight at all. Nothing I can do about it but moan.. :lol:

Phil

I'm afraid you are showing your lack of building experience here, it is completely normal for ribs to be balsa, the only time you will find ply ribs would be in high stress areas eg supporting wing tubes, retract plates, sometimes root ribs etc.

Modern artfs are generally very well designed structurally, no full length ply reinforcement to balsa fuselages, again completely normal, ply at the front to support engine and wing mounts then balsa from behind the wing would be the norm. They are designed to cope with in flight loads, not impact loads. You could use more ply to make them stronger but you will just add weight and compromise the performance. If you try to make them crash proof they would fly like cr*p.

I tested my Curare fuselage after reading your earlier comments by trying to twist it, but it is very stiff, no need for more reinforcement.