Levanter

FB3 I don't know how many fuselages you are going to build given all the advice so far . Acetone will attach both epoxy and aliphatic. If you soak the balsa side with acetone and work on an edge, you may be able to separate them bit by bit. I suspect the ply is more valuable both in terms of money and time expended so if the worst comes to the worst you could sacrifice the balsa (some bits will get re-used) and save the doubler. I am always making mistakes and having to work around them - part of the fun. A learned mentor of mine said to call them "features". Levanter

Posted by kc on 08/02/2019 16:40:14: Actually all you really need for wing building is just the lines for the spars and LE & TE and lines for the ribs. No real detail is required so just trace those lines or draw on plain paper or the building board. + 1 As kc says. You only need one line for the ribs, choose inboard or outboard. One line for the leading edge where I would normally use the outside line so if there was any variation in the wood size it would not affect the planform. Likewise for the trailing edge. Really just a few lines on some blank paper. Much quicker, much cleaner, cheaper and no need to cause damage to the original. Levanter

FB3 What glue did you use and how long ago? Levanter

FB3 You will enjoy building the Isabella and it comes out at a nice size for me with limited space. Mine is powered with an OS LA 10 but has not flown yet. To sharpen my aerial tubes I "wipe" the ends across the coarse side of my Permagrit. This raises a burr on the inside and the outside. So quick to do and the burr helps to stop the aerial binding in the hole and also make pushing the core out much easier especially if drill through thick balsa. Thank you for the kind comments. Levanter

FB3 Yes it is the Isabella designed by Marco Penk from the RCM&E September 2018. I already have one Isabella so this one is Isabella II or Due in Italian. The fuselage is more or less as the plan but I used my own method (copied from Peter Miller really) for the wing. It has dihedral rather than polyhedral which made the wing simpler to build and allowed me to move the ailerons outboard. It is quite a cutie. Levanter

FB3 This could be for next time. What I do is drill the two ply doublers back to back at the same time. To hold them together and aligned while I drill and do other work I use a few dabs of Pritt Stick. (it wipes off with a damp cloth). You can use an ordinary drill as 3/16" is not that big and me, I wouldn't bother with a pilot hole at that size. Micro precision on position is not that critical as long as they match. Absolutely drill onto a scrap piece of ply or wood to stop breaking out. The doublers can then be stuck to the fuselage sides and the drilled holes make a perfect guide for a sharpened piece of aerial or suitable tube to cut out the balsa. The doublers act as a jig. For similar reasons I do as much as I possible can on any doublers before gluing them, like lightening holes, servo rails etc. Levanter

I bought a second-hand scroll saw and never used it so cannibalized some parts and junked the rest. I had a Draper bandsaw (again second-hand) but it was the 3 wheel type, very bulky and also noisy so that went the same way. I now have the Proxxon bandsaw which is a peach and the Proxxon table saw and could not be without either. My favorite job for the bandsaw is tapering spruce wing spars which would be a real pain doing by hand. The combination of these two has increased the speed of my building no end as well as helping with precision. For inside cut-outs I start by chain drilling and then smoothing out the profile with a small drum sander in a Dremel. If I was to get another saw it would be the next size up Proxxon table saw that also has a tilt function for the blade. I would find that very useful and it is on my wish list. Are you listening Santa! Levanter

Hi Stephen Your Sonata looks really nice. Congratulations! I am building an E version but the build has got stalled while I sort out a couple of RC yachts for the summer. Actually it mainly just need covering and I am a big fan of the fluorescent green as well. Good to see the air brakes or spoilers. I would be really interested to know how you organized the servo linkage and what sort of travel you get? Also what the all up weight is. I am expecting mine to be heavier because of the motor, prop and larger battery but it is a big wing and should cope. Levanter

The aircraft is flying in a mass of air and doesn't know whether it is moving upwind or downwind, or across wind for that matter. If you think about it how can it? if there is wind, this mass of air is moving relative to the ground and therefore when the aircraft is being observed from the ground (rc pilot) it looks like it is going at different speeds but that is relative to the fixed point (ground) and not the moving air mass. Taken to extreme and the windspeed is greater than the airspeed and the aircraft can appear to stand still or even go backwards! But we all know that is "impossible" in aerodynamic terms zo we readily accept the concept of a headwind. Same thing applies to currents and tides when sailing. It also explains the common and infamous stall on the downwind turn. So Simon, I think you are being deceived by appearances and Martin is in fact perfectly correct and his explanation was spot on. It is an important subject. Levanter

Posted by kc on 21/01/2019 12:59:05: SLEC advertise " plan tracing, laser & router cutting service" Drawing boards forever! I would love to get hold of a decent one. Not sure where I would put it but I would find somewhere. So many thousands must have been scrapped and I wish that I had grabbed one. Levanter

Robert For cutting I use the Dremel diamond slitting wheel. It goes through carbon like cheese. Be aware also that the fine black dust can "soak" into wood, especially light balsa and stain it. I learned the hard way! Levanter

I used SLEC from Mallorca. Everything top notch. Next order going there too. Not to reflect bad on the others as I have not dealt with them. Levanter

Erfolg Sometimes the hardest part of a job is simply starting. I should get stuck in if you would pardon the pun. The beauty of epoxy is that it is an adhesive so if you end up on the flimsy side you can always add another layer or two and exactly where you want it. If on the other hand you have reverted to heavy engineering then simply grind a bit off. You are going to paint it anyway?? I am a shipwright by trade and that was building steel ships up to 10,000 GT. Heavy stuff indeed with equal heavy bits. Delicate is just the other end of the same spectrum. Levanter

Erfolg The more sophisticated the mould tools, the less cleaning up their will be to do and with a closed mould you can have finished edges as well. The problem with that is will make only one size and would be overkill anyway. Looking at you photos you have got the basics and after you have finished the moulding it will be an easy job to dress the edges smooth and you have some license to vary the chord, curve the edges and even adjust it to an aerofoil section if you wanted to go really mad. A larger number of thinner fabrics will be much better than a few thick ones. If the weave is coarse, the layers are held apart and fill with resin. This will have a poor strength to weight ratio. The other advantage of using multiple layers is that you can taper the thickness. The layers can be successively stopped short as you get closer to the wheel fixing. This will be efficient and give you a greater deal of suspension. Your parcel tape will be fine but don't get any creases in it. It will also help achieve a good finish on both side if you could clamp boards to the outside surfaces. You could use the tape again as a release surface but wax and apply release agent anyway. The clamping pressure nd settings can be adjusted to keep the arms equal thickness and excess resin will be squeezed out with considerable benefit. Don't use the Kevlar as it does not "wet out" easily as well as being hard to cut. If you have a diamond disc cutter then fine. Kevlar is great material with extreme toughness but needs special techniques to benefit from these properties. Carbon can be made very light but is very stiff and unforgiving. That's why I don't like it for undercarriages and I am willing to bet you make something that is well over strength anyway. It will be messy nd I would definitely use epoxy following the good advice in earlier posts. Levanter It is likely to be messy

FB3 Aliphatic is not really a gap filling glue and any that are will add unnecessary weight. The strongest glue joints are best made close fitting. It seem your gap in the stringers is big enough to notice but not as you say enough to fit slivers of balsa which was KC's good suggestion. Your problem is quite a common one and instead of trying to fit thin strips you can easily cut small wedges. There are many ways to do this but even a shaving off the edge if an offcut will generally do. Fit the stringer in the notch as normal. Put some glue on both sides of the wedge and slip it into place. It is best to leave them like this until the glue has dried when the joint will be stable. The extra can be trimmed off and then lightly sanded back to the correct level. Easily done in a fraction of the time it takes to describe it. I frequently have to do this whether by accident or design. Levanter

Posted by SR 71 on 12/12/2018 07:00:54: Hi Bruce i make my own tanks to fit my builds, i do them in fibre glass, i first make a plug the shape i need from blue foam, i glass it with epoxy resin and cloth, i cut the tank in half and remove the foam and the fibre glass layer, fit the connectors in and join the two halves with fibre glass, never had one fail, and i use them for both glow, petrol and in my jets Tony Tony What sort of finish do you get on the blue foam using multiple coat of release agent and what release agent do you use? I am wondering is the core could be made using a foam that dissolves (in acetone or cellulose thinners perhaps) so that the tank did not have to be cut in half. Can you explain how you make your connections. Are they mechanically fastened or do you bond them in? I am still very interested in the 3D printing possibility but have toyed with the idea of laminating the tanks for a while now. Many thanks Levanter

Posted by John Stainforth on 11/12/2018 22:01:33: The problem is that all 3D printed objects are very porous at a macroscopic scale. To properly seal a 3D printed tank would be very difficult. There is the additional problem that all plastics and plastic fillers are permeable at a molecular level and most model fuels are very aggressive penetrants of plastics. John All the tanks I have are from some kind of plastic. We are probably saved from the effects you mention due to the tanks being empty for most of the time. In full sized boats, diesel and petrol tanks can be made from plastic and I suppose these are made from carefully specified materials. Levanter

FB3 I think I know what you mean and you are restricted in the width of the sheet of balsa perhaps? Is it possible to use vertical grain as much as possible, then the piece you have to join would probably not matter which way it was orientated. Levanter

Martin I think what Erfolg said was brown packing tape otherwise know as parcel tape. When I was laminating professionally we used it as a parting surface for non-critical surfaces but still important to wax and use release agent as belt and braces. For the undercarriage it should be perfectly acceptable presuming the moulding will be dressed and painted. The only thing to avoid is getting the tape creased as this makes a male feature in the mould and a female feature in the moulding that will need filling. Levanter

Posted by conrad taggart on 28/11/2018 12:41:31: Posted by Steve J on 27/11/2018 13:23:37: Posted by Andy Symons - BMFA on 27/11/2018 12:31:38: When you consider the CAA regularly mention what a "very good thing" it is to have a publication pretty much guaranteed to land on every members doormat 6 times a year If the CAA think that the BMFA News is a "very good thing", how about asking them for some cash to help pay for it? Steve Exactly ! Weird as Austin, Texas!!   Edited By Levanter on 28/11/2018 14:15:02

Posted by Steve J on 27/11/2018 19:06:43: Posted by Guvnor on 27/11/2018 15:40:38: having failed to look for any urgent safety or technical notices I wouldn't expect somebody wishing to promulgate "urgent safety or technical notices" to rely solely on a magazine that is published six times a year. Steve Nor would I Steve. If it was really that urgent that it had to go out immediately I am sure there would be many other means of getting the message out. Otherwise for technical notices, once every two months sounds more than adequate even if there were that many notices. Levanter

Bizarre suggestion Steve. I would think that if you asked the CAA if magazine RCM&E was a good thing they would say yes too. Can't imagine Mr Ashby would get anything from the CAA except some very funny looks. Levanter

Hi Andrew I think a photo could help here but here's some thoughts anyway. The strength of the wing joint will be in the dihedral braces (if there are any) or the bandage bonded to the wing skins. Using epoxy to fill the gap would probably be an overkill and would only be as strong as the bits it is stick to. It would also add unnecessary weight and could be difficult to sand without damaging the adjacent material if it was not dead smooth. I have had a similar problem before and now tend to put the ribs at the wing root in at the last minute which can help. In this case it sound like the mating ribs are not straight so I would glue a wedge shaped piece of balsa say 3mm thick at the widest point and tapering to nothing 2 inches in on each rib. You then have a little bit of meat so and off to get a good mating fit. Quick and easy with no significant weight gain. It has worked for me. Levanter Bob beat me to it with the balsa.  You have a dihedral brace so no real strength required at the gap.  Just enough to keep alignment which is what you would have anyway if the ribs made contact.  A large number of my builds don't use epoxy anywhere.  Mainly aliphatic with some occasional cyano.   Edited By Levanter on 27/11/2018 14:10:50

Hi Geoff They are the large and medium rigs for an International One Metre. I also have a couple of obeche masts for another yacht that is awaiting repair after being attacked by a Rottweiler. Yes - Seriously! Funnily enough the hull was in the bath yesterday checking for leaks (none found in the hull) as I have an urge to get it back on the water this winter. We sail in bays and harbours so it gets a bit rough sometimes and water always seems to find its way in somehow but now I know it is through the deck. Levanter

Stephen Two layers of 4mm with the joints staggered. The corks tiles are self finished so paint, glue, water and anything else I can think of throwing at them wipes off easily. The cork is also kind on the blades and razor saw when I can't be bothered to go and get the cutting mats for a quickie. I also have a 1.2m IKea plain white kitchen table that is cork topped. It was not dead flat but a couple of steels screwed on the underside fixed that. Levanter