how protect vane in a windvane

[xxhat]

All wind vanes use a wood vane to detect the wind and adjust the tiller.


This wood vane has to be light. What is the best way to protect the wood vane from cracks or breaking ?


1. Expoxy but this may add too much weight


2. varnish


Any other ideas ?

[Snowpetrel]

I just used a decent oil based marine paint, and stored it below when it wasn't in use. Be careful not to add to much weight and check the balance afterwards. If need be you can drill big holes near the top and cover them with thin plastic.

[conachair]

Marine ply lasts for years unprotected. Or maybe something like woodskin to make it look pretty. You need some spares anyway.

[Suijin]

The new Monitor windvanes are made of corrugated plastic, trading durability for responsiveness and performance.

I treat them as consumable goods. I have a set of spares (regular and light wind) and made another set out of luan plywood that I sealed with polyurethane that I had lying around.

[Snowpetrel]

^^ Sujin, it looks like that vane has two fibreglass rods up inside them, have I got it correct?

If so it's a good idea, as I once destroyed one of those twin wall polycarbonate vanes that didn't have any reinforcement.

[Suijin]

I never noticed those before, despite having shedded one of these in the past. Maybe it was an older iteration without them.

They appear to be simple wooden dowels slid into the channels. At first I thought they were pvc tubes but they are tapered at the top end, probably to make insertion easier. Can’t see them directly as they are sealed inside.

FYI I think the idea of drilling holes in wooden vanes and covering them with plastic is brilliant. Gonna try that next time I make a set.

That said, there is some balance involved particularly in light air. The vane needs to be heavy enough that it’s not overwhelmed by the counterweight. I might make a few prototypes to test. Then again, it’s never the light air vane that gets the rough treatment.

[a64pilot]

Originally Posted by Snowpetrel

I just used a decent oil based marine paint, and stored it below when it wasn't in use. Be careful not to add to much weight and check the balance afterwards. If need be you can drill big holes near the top and cover them with thin plastic.

Look up a product called monokote, it’s been used to cover the wings on model airplanes for a Looong time. The old school method was silk and dope, lots more work, but stronger than monokote.
Weight of monokote is zilch.

The holes your talking about actually have a name, been done in aircraft construction likely since the Wright brothers, they are called lightning holes, cause of course they lighten something.

[Snowpetrel]

Originally Posted by Suijin

I never noticed those before, despite having shedded one of these in the past. Maybe it was an older iteration without them.

They appear to be simple wooden dowels slid into the channels. At first I thought they were pvc tubes but they are tapered at the top end, probably to make insertion easier. Can’t see them directly as they are sealed inside.

FYI I think the idea of drilling holes in wooden vanes and covering them with plastic is brilliant. Gonna try that next time I make a set.

That said, there is some balance involved particularly in light air. The vane needs to be heavy enough that it’s not overwhelmed by the counterweight. I might make a few prototypes to test. Then again, it’s never the light air vane that gets the rough treatment.

It would be interesting to try staggered carbon rods to get a much stronger vane using the twin wall. Mine destroyed itself more because it was too flexible. At about 30 odd knots it started flapping and oscillating. While I was digging out the plywood vane it buckled at the base and cracked. At least it was easy enough to cut down and reuse, but I no longer trusted it, and the plywood vane worked nicely.

My best strong wind vane was a tapered plywood one. Near 4 foot tall, by only about 2 inches at the top. This one was awesome in 10-40 knots.

My lightning holes where actually more like rounded triangles in a tapered shape. And mine was covered with a removable sleave of spinaker cloth, but that aircraft covering or something like heatshrink solarfilm would be perfect.

Also consider moisture uptake. Over time my plywood vanes got slightly heavier. Epoxy would help keep the moisture out.

[Snowpetrel]

Here is a picture of what it looked like. I kept cutting the holes bigger until it balanced correctly. And the taper was to keep the strength where it was needed.

[Snowpetrel]

Originally Posted by a64pilot

Look up a product called monokote, it’s been used to cover the wings on model airplanes for a Looong time. The old school method was silk and dope, lots more work, but stronger than monokote.
Weight of monokote is zilch.

Sounds like the same stuff as the solarfilm we used as kids to cover the wings of our RC airplanes and gliders. Shrink it with an iron (not to hot...) I wonder how it holds up to UV long term. Might also help keep the water out.

[JeffH]

Doesn’t the weight of the vane have to match the weight of the counterweight?

[JeffH]

I think this is a place where spelling matters. It’s lightening holes in this case; lightning is the stuff from the sky that fried your VHF transceiver. [emoji41][emoji868]

[jasbee]

We used corrugated plastic (Corflute). It doesn't last forever and over time tends to break at the base where it is bolted to the vane mechanism, but it's just a matter of bolting on a replacement. We always carried 6 or 8 spares and didn't have to replace often.
You definitely need a material that is very light in order to react to wind shifts and it's a balance and compromise to find something light enough and at the same time with some degree of strength. In our experience plywood is far too heavy - even thin plywood.

[Russ]

Since you asked about varnish, the best stuff is Clear Penetrating Epoxy Sealant or CPES. It will stiffen the wood but basically it is the best waterproofing.

Redcoat whenever, no sanding or prep.

Russ

[model 10]

[QUOTE=JeffH;2690351]I think this is a place where spelling matters. It’s lightening holes in this case; lightning is the stuff from the sky that fried your VHF transceiver.

There is that, but the major reason for adding lightening holes in an aircraft structure is for strength. The edges of the holes are rolled and add stifness.