airplane construction

Bill Watson wrote:

The more you know the more you can do.

Nothing like assembling a sailplane, loading it full of water and
bombing down a ridge at red-line for a few hours.

Then you just pull the wings and tail back off and trailer it home.

the size of those pins/bolts that hold the wings on should attract the
attention of any pilot not used to rigging sailpanes :-)

Understand that bolts used in aircraft construction are not
"hardware store" items. The steel and the tolerances for
aircraft grade fasteners are better than hardware store
Grade 8 bolts. Beech uses bolts in tension to hold the wing
on the Bonanza, Baron and King Air models. When there is a
crash, the bolts are rarely broken. But if the bolts are
not properly installed and maintained, corrosion can weaken
the bolts causing them to break.

Cessna uses a bolt installed in shear through fittings like
you fingers meshed. This is called "double shear" and as
long as the bolt is a snug fit in the hole the bolt can hold
more load than the airplane is designed to experience.
But a bolt in tension is stronger than a bolt in shear.


"george" wrote in message
ups.com...
|
| Bill Watson wrote:
|
| The more you know the more you can do.
|
| Nothing like assembling a sailplane, loading it full of
water and
| bombing down a ridge at red-line for a few hours.
|
| Then you just pull the wings and tail back off and
trailer it home.
|
| the size of those pins/bolts that hold the wings on
should attract the
| attention of any pilot not used to rigging sailpanes :-)
|

Jim Macklin wrote:
Understand that bolts used in aircraft construction are not
"hardware store" items. The steel and the tolerances for
aircraft grade fasteners are better than hardware store
Grade 8 bolts. Beech uses bolts in tension to hold the wing
on the Bonanza, Baron and King Air models. When there is a
crash, the bolts are rarely broken. But if the bolts are
not properly installed and maintained, corrosion can weaken
the bolts causing them to break.

Cessna uses a bolt installed in shear through fittings like
you fingers meshed. This is called "double shear" and as
long as the bolt is a snug fit in the hole the bolt can hold
more load than the airplane is designed to experience.
But a bolt in tension is stronger than a bolt in shear.


The hardware-store Grade 2 bolts (no marks on the head) is
around 55 to 60 ksi, really dangerous stuff on anything other than your
kid's push kart. Grade 5 (three radial marks on the head) are 120ksi,
same as an AN bolt. The Grade 8 (five radial marks) is 150ksi, better
than the AN bolt.
But the AN bolt is made of 2330 nickel steel, making it more
corrosion-resistant and more ductile, which means it will stretch more
before it breaks. The part will appear loose before it comes off. The
AN bolt's tolerances are a bit better and the thread length is just
what's needed, not the great length of thread on the industrial bolt
that ends up inside the joint where it doesn't support the shear loads
well. And the thread fit is far better on the AN bolt.
Shear strength for steel is typically 70% of tensile.

Someone asked about the Cardinal's (177) wing attach. It's been a
long time, but I think it was something like 1/2" bolts in sextuple
shear, spaced about 7 inches apart. The spar fittings were cast
aluminum.

Dan

Jim Macklin wrote:

Understand that bolts used in aircraft construction are not
"hardware store" items. The steel and the tolerances for
aircraft grade fasteners are better than hardware store
Grade 8 bolts. Beech uses bolts in tension to hold the wing
on the Bonanza, Baron and King Air models. When there is a
crash, the bolts are rarely broken. But if the bolts are
not properly installed and maintained, corrosion can weaken
the bolts causing them to break.

Cessna uses a bolt installed in shear through fittings like
you fingers meshed. This is called "double shear" and as
long as the bolt is a snug fit in the hole the bolt can hold
more load than the airplane is designed to experience.
But a bolt in tension is stronger than a bolt in shear.

I'd have to pull out my AISC manual to be sure, but I believe that a
bolt in double shear has more capacity than in tension. If you are
comparing single shear to tension, then I agree with you.

Matt

"Jim Macklin" wrote in message
...
...
Cessna uses a bolt installed in shear through fittings like
you fingers meshed. This is called "double shear" and as
long as the bolt is a snug fit in the hole the bolt can hold
more load than the airplane is designed to experience.
But a bolt in tension is stronger than a bolt in shear.



But you don't want to be standing under the wing if someone jerks the stut
off.

Boink!!!

;-)
--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Jim Macklin wrote:
Understand that bolts used in aircraft construction are not
"hardware store" items. The steel and the tolerances for
aircraft grade fasteners are better than hardware store
Grade 8 bolts. Beech uses bolts in tension to hold the wing
on the Bonanza, Baron and King Air models. When there is a
crash, the bolts are rarely broken. But if the bolts are
not properly installed and maintained, corrosion can weaken
the bolts causing them to break.

Cessna uses a bolt installed in shear through fittings like
you fingers meshed. This is called "double shear" and as
long as the bolt is a snug fit in the hole the bolt can hold
more load than the airplane is designed to experience.
But a bolt in tension is stronger than a bolt in shear.


"george" wrote in message
ups.com...
|
| Bill Watson wrote:
|
| The more you know the more you can do.
|
| Nothing like assembling a sailplane, loading it full of
water and
| bombing down a ridge at red-line for a few hours.
|
| Then you just pull the wings and tail back off and
trailer it home.
|
| the size of those pins/bolts that hold the wings on
should attract the
| attention of any pilot not used to rigging sailpanes :-)
|


Here's a good illustration/animation on "double shear" connections:
http://www.ijee.dit.ie/OnlinePapers/...ted_double.htm

--
Mike