Typical traditional bonding from the thirtys this photo shows the rear spar area with the metal bits bonded with copper braid and small wires.
A modern carbon composite wing with the metal parts bonded with large cables.
Another modern aircraft of metal and carbon construction showing the wing fuel tank area bonded with large cables to the metal fuselage structure
The way the French do it ! These copper braid bonding cables are found all over the DR 400 bonding all the metal bits together.
This is a bit odd. There is something called galvanic corrosion. Carbon composite and aluminium is a particularly poor combination (for the aluminium). The bonding wires also creates a system where every bit of aluminium is made into a sacrificial anode. There are other factor involved like exposed unpainted areas, moisture etc, but still, every piece of aluminium has an increased potential for corrosion by a factor million or thereabout? Even bicycles goes to great length isolating carbon structures from aluminium.
Another reason for all alu construction.
That’s really interesting, A&C.
Those are heavy cables, obviously intended for a lightning strike.
I recall hearing of multiple cases where lightning melted a glider’s control cables.
I still don’t know how the homebuilt business deals with this, because you absolutely can get a strike flying in perfect VMC, under a big dark cloud.
Perhaps that is why I was taught to never fly under big dark clouds?
Lightning can strike at an angle, well away from the CB.
Yes of course. Death can strike always, any time, any place. Think twice before leaving your cosy bed tomorrow morning.
It can, but there is a difference between having no bonding (and being limited to days where there is absolutely no convective activity – not even a TCU – within many miles) and having bonding (and being able to fly VFR in the normally understood way).
I am not having a go at any particular type of aircraft. I am just trying to understand the thinking process behind somebody building an aircraft which is so vulnerable to something which is rather common. And bonding is not exactly expensive.
And the control cables in homebuilts are not all that thick… take a walk around the Friedrichshafen show and in a few minutes you can see how 450kg or 750kg or whatever is being achieved.
The stats on crashes caused by lightning are probably almost nonexistent but that could simply be due to risk compensation i.e. those types fly almost totally only on perfect days. Certainly that is what one sees here in the UK and right across light GA, across everything from microlights to say PA28s. Risk compensation is a huge factor in GA.
VFR in the normally understood way
Please to elaborate?
(btw my own pride and joy is cloth over steel tube – not a deliberate choice but it does come in handy. Still I’ll avoid flying under thick black cloud, and near other nasty things)
