Wing Fold & Locking Mechanism
Thread Starter
Join Date: Feb 2000
Location: Vic
Age: 53
Posts: 444
Wing Fold & Locking Mechanism
Looking at a typical aircraft with folding wings such as the Skyraider.
When the wings are unfolded, how is the stress from airloads on the outer wing panel transmitted through the join in the spar. Logic would suggest that some locking pin is used, but the pin is smaller than the spar, so how does the pin not that is much smaller than the spar carry the loads. Is it as simple as a bloody strong pin?
Join Date: Jan 2014
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Originally Posted by Ozgrade3
Is it as simple as a bloody strong pin?
How folding wings work.
Join Date: Mar 2001
Location: I wouldn't know.
Posts: 4,190
I would suggest going to the next glider field and checking out how the wings are secured there, after all they are built to be taken apart easily (folding the wings, often at several points along the wingspan), also to carry the loads once everything is back in place. And they have design at least +5.3g/-2.65g in normal operation (yes, every glider is according to EASA at least an utility category plane). From my experience, and that is a bit out of date, it is usually one or two bolts for the central point, and quite small pins for mid to outer span points.
Join Date: Dec 1999
Location: uk
Posts: 697
On the Buccaneer it pretty much was a bloody great pin.
On this picture, about 1/3 of the way from the left hand edge of the wing there is a pale grey ‘spade’ shaped thing with a hole in. When the wing was unfolded, that would engage with the sloped bit on the inboard section of the wing and then the big pin would sequence down through the hole.
HtH
On this picture, about 1/3 of the way from the left hand edge of the wing there is a pale grey ‘spade’ shaped thing with a hole in. When the wing was unfolded, that would engage with the sloped bit on the inboard section of the wing and then the big pin would sequence down through the hole.
HtH
Join Date: Feb 2009
Location: Toronto, Canada
Posts: 27
@ the original poster:
One can also have a steel pin in steel fittings, attached to aluminum spars.
Google something like 'Corsair wing fold mechanism'. I'm not sure but there seems to be just a main spar pin to take mainly bending forces (rotating around a top one, pinned at the bottom), and some mechanism near the leading edge to take torque forces.
Bigger faster aircraft may use a bunch of pins. (Newer ones will also be certified under 'fail safe' rules requiring more damage tolerance, designs where even for the wing in general, there isn't just 1 critical spar, but a bunch of spar webs in the wing.)
One can also have a steel pin in steel fittings, attached to aluminum spars.
Google something like 'Corsair wing fold mechanism'. I'm not sure but there seems to be just a main spar pin to take mainly bending forces (rotating around a top one, pinned at the bottom), and some mechanism near the leading edge to take torque forces.
Bigger faster aircraft may use a bunch of pins. (Newer ones will also be certified under 'fail safe' rules requiring more damage tolerance, designs where even for the wing in general, there isn't just 1 critical spar, but a bunch of spar webs in the wing.)
Join Date: Mar 2019
Location: London
Posts: 19
No question about the "bloody great pin" a third of the way down from the left-hand side of the pic, in fact the top of that pin is visible. It works vertically. However, the red locking fork on the right is surely a transit securing piece that's removed prior to flight? It too has a pin that operates horizontally and it is more clearly visible.
I think.
I think.
Join Date: Aug 2001
Location: UK
Posts: 1,853
IMHO it's very clever engineering, not just the hinge and locking mechanism, but also pivoting fuel and hydraulic lines, control runs, electrical feeds, and in the case of the Buccaneer, ducting for the 'blown lift'.
Join Date: Dec 2009
Location: Southwater
Age: 70
Posts: 0
Originally Posted by Ozgrade3
https://www.youtube.com/watch?v=1F23RciUwDE
Looking at a typical aircraft with folding wings such as the Skyraider.
When the wings are unfolded, how is the stress from airloads on the outer wing panel transmitted through the join in the spar. Logic would suggest that some locking pin is used, but the pin is smaller than the spar, so how does the pin not that is much smaller than the spar carry the loads. Is it as simple as a bloody strong pin?
Looking at a typical aircraft with folding wings such as the Skyraider.
When the wings are unfolded, how is the stress from airloads on the outer wing panel transmitted through the join in the spar. Logic would suggest that some locking pin is used, but the pin is smaller than the spar, so how does the pin not that is much smaller than the spar carry the loads. Is it as simple as a bloody strong pin?
Does a piston engine have a choke for a cold start? Or is there another arrangement like the fifth injector on my car?
Join Date: Mar 2005
Location: N/A
Posts: 3,714
Does a piston engine have a choke for a cold start? Or is there another arrangement like the fifth injector on my car?
Join Date: Nov 1999
Location: UK
Posts: 1,594
so how does the pin.......that is much smaller than the spar carry the loads. Is it as simple as a bloody strong pin?
Join Date: Jan 2008
Location: Reading, UK
Posts: 12,634
Originally Posted by Uplinker
As I understand it, the weight and forces from underslung gas turbine engines, on today's passenger jets, are transmitted to the wing with just two pins. They are big pins though.......
The 737NG, for example, uses eight bolts and three shear pins:
