Wing rigging practices- German v British

[YavorD]

Good point, Romani. Multi-threaded cable is much more flexible, damage-tolerant and easy-to-handle (user friendly ) in comparison to RAF-wire. Strength for the same cross-section can be somewhat better, too.
Regards,
Yavor

[Rowan Broadbent]

Yavor, Romani, thanks for your input.

The point about rafwires is well made, but the double-flying-wire practice was in use before the advent of rafwires. viz: Bristol scout, BE2c.

As far as the French use of double wires is concerned, I was particularly thinking of the SPAD XIII which, if I recall, had double flying wire cables bound together, rather than rafwires.

[KACEY]

Originally Posted by Romani

I am not technically qualified to comment, but I will do so anyway in the hope of contributing something

RAF wires are "ribbons" of metal while standard bracing wires were coiled wires. Since is often hard to tell in photos and many museums and replicas and extant flying airplanes use substitute steel tubing due to the cost of replicating the original wires (either RAF or coiled wires)

Hi there Romani,

Actually RAFwire is not wire at all it is a solid streamline tie-rod. (either cold drawn or cold rolled) See the Brunton site below:

Steen Aero Lab - Bruntons Flying Wires

So I'm thinking it was stronger and more damage resistant than any other equal load wire.

As DSA pointed out the double flywire design, the British came up with, would give a little bit of saftey margin if wire damage was occurring, however I feel they did it more for the drag reduction benefits of the smaller wires.

Then they also discovered that placing a wood fairing between the two wires converted it into a streamline wire assembly (i.e. greatly reduced drag).

Anyway, that's my take on RAFwire & doublewire, again.

Respectfully Submitted,

KC

[Dan_San_Abbott]

Rowan:
Without looking up what force factor was used my most WW1 air forces, probably, a factor of five, or five times the weight of the aircraft. An S.E.5a weighed about 2100 lbs fully loaded times five equals 10500 pounds. The eight flying wires, each flying wire then supported approximately 1312.5 pounds. However a design safety factor was then applied to that force, say a design safety factor of two was used, the minimum strength of that wire must be 2625 pounds or better. Looking up the RAF streamilne wire, it would be the 1/4" b.s.f. 3450 lbs tensile strength wire. Which is what I believe the S.E.5a has for flying wires. The engineer then selected a wire nearest to that number. The safety factor becomes, 3450 lbs. divided by, 1312.5 lbs equals 2.62 design factor.
The flying wire wire attachment fitting, the terminal ends of the flying wire had also to be of a strength the be in excess to 2625 pounds.
In parachute design, personal parachutes had a design factor of 3.77, whereas a cargo parachute of 1.5.
In the case of aircraft, the engineer has to make a determination of the estimated maximum weight of the aircraft, from that he can then doi the detail design. In the cae of parachute, maximum airspeed is the criteria, and from that figure we can make the detail design., In both cases it is the worst case scenerio.
Blue skies,
Dan-San