Nigel R

Moisture speed up the curing. Your fingers are slightly moist because we're animals... Unlike that nice dry balsa you actually want stuck... Similarly, breathing on cyano seems to cure it rapidly (thus, I've never bought activator)

Less than solarfilm would cost.

I'll put a fiver on it being constant chord and therefore the same wing loading...

Seagull Boomerang is, what, 6lb, time its fitted out? I'd be surprised if a Hi Boy was much different. Here's an unstarted kit on ebay One of the big plus points for this kit - in its day - the interlocking fuselage parts meant you had a good chance (as a beginner) of ending up with a warp free model. Foam wings also meant things were (in general) straight. All fairly quick to put together, too.

Unicorn on outerzone Looks like a really nice basic sport aerobat with minimal build time / effort. I'm sure I have a spare 60 or two somewhere around here...

Numbers... Expansion for nylon is around 0.1mm, per degree, on a meter of nylon. For 40 deg change in temp (a fairly extreme case!) - that gives 4mm on 1000mm, (or 0.4%) - note for a whole metre though. I'd make an assumption (dangerous) that the protrusion from either end of a control run is 25mm, giving 50mm total (as this is about what I believe the instructions call for, "no more than 1" sticking out") With a correctly fixed snake, we only need to worry about the bit sticking out - that would give, for that 40 degree rise, a much smaller change in the control run - 0.2mm change. Another assumption - most of my installs use a standard servo with a standard arm and would probably show a total movement of around 1/2" (say 12mm) either way. In my typical install, the expansion/contraction over our 40 degree change is approx 1.5% of the servo movement in each direction. I can't say I fly in 40 degree weather very often but I appreciate countries other than the UK exist! Most of my flying occurs between (say) 10 degC and (maybe) high 20s deg C, so the change I see is much less, about half. YMMV. For me, snakes are easy and work "sufficiently well".

https://www.nexusmodels.co.uk/sullivan-2mm-gold-n-rod-nylon-type-semiflex-48-inches-1219mm-f-sln576.html £23! Safe to say I'm finding that quite a lump to swallow for four clevis, four bits of studding, and two nylon inners and outers. That said, they have changed the colour, maybe that's what you're paying for. Either way 2-56 hardware is not hard to come by. Matches my experience, perhaps a click on or two on a hot summer day.

Snap (well, I made about four flights, I think). It wasn't a bad airframe, I was a bad pilot!

The topic has come up on the forum a few times, I believe. The outer and inner are made from the same stuff and expand/contract at the same rate. If you fix the very ends of the outer, and only the very ends, and leave the middle "free to expand", then any change is matched by any change of the inner rod. Done this way, the only expansion that affects trim is the very small piece of inner that protrudes from the outer, that very last inch at each end. The expansion on 2" of nylon rod is small. in order of a few thou per 10 deg C, if my sums are right. I appreciate this is not possible as a retrofit for an existing install.

Oh good gosh why have I not thought of those doohickeys before.

Incidentally. Dubro lazer rods are very good and come as a complete kit with studs and clevis etc etc. They are still fairly priced too (unlike the now absurdly priced sullivan snakes I used to buy)

Fairly sure it's a weird thread specific to spokes. I've built a few wheels too. DT Swiss swaged spokes every time...

Would the brass joiner be solid enough to butt join two torque rods? I admit I'd prefer to use the screw fitting that these come with, as it gives some scope to fine tune / adjustment.

I would need to thread both ends. Would work with mild steel but I'm skeptical about being able to thread piano wire. Maybe I should try that. Either way the commercially available rods are too short, sadly

No, the brass tubes are to flatten and drill, one at either end of the torque rod. It's to link two inboard servos with outboard twin rudders. Surfaces are too thin for burying a servo. My other idea was to bury a bell crank but I preferred the torque rod idea so I'm trying that first...

You only need about an inch of threaded rod at the end of the snake. as suggested already, M2 studding is available from many shops, just cut it down as you need.

spare ribs..? 🍖

I don't know much about alphabetic glue I'm afraid... Peter's suggestion is probably the best route forward for you. Should be plenty strong enough. Thin, properly thin, cyano, can make balsa a lot stiffer and cracks like this are made almost as strong as the original wood, if you're careful about the repair. The trick is making sure you've pulled the wood out so that it is all back in exactly the same place again. In the past I've poked a hole in the sheet and used a bent piece of wire to pull sheeting back out to flat, before using the thinnest cyano to soak into the crack

Not sure I follow - how I could use the ball of a ball link?

where is the crack? wing root, tip, or in the middle?

I have a large pile of (old, but perfectly viable) Graupner Super Nylon grey IC props. Guess what I use on my small electrics (and on a few IC setups, too)...

Thanks Martin, yes that was the worry point, getting inside the tube to clean, it'll have to be flux.

Thanks chaps. My usual with piano wire is some fresh fine grit paper, then leave the flux in place for a good few minutes, then tin. Seems like this will be just more of the same 🙂

Question for any seasoned metalworkers out there. I'm somewhat familiar with binding and soldering piano wire for UC and cabanes and suchlike, or soldering mild steel washers to piano wire, but, I've not soldered brass tube to piano wire. Intended use is for a DIY torque rod which needs to be, a) longer than the usual prefab 12g offerings and, b) double ended (!). I have some KS tube & wire which fits together perfectly. Is there anything special I need to know about prepping? My toolkit is a basic torch, leaded solder and flux.

It's really not. You can just note down where the slots are on a bit of paper, or on the plan. I much prefer to have all gear and the various rods & linkages in place and working at the earliest point possible, i.e. before going near covering. Horses for courses.