airplane construction

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.

Robert M. Gary wrote:
Mike wrote:
Hi,

I'm interested in learning more about airplane construction, say maybe a
Cessna 172. I know the basics of airframes and power plants, but what
I'm having a hard time finding is actual diagrams and depictions of the
actual assembly. For example, wing root connections, engine mounts,
supporting structures, etc. I imagine this might be available in a
mechanics manual, but I don't know where else to look. I've scoured the
Internet with no success.

When I saw how the wings are attached on a Cessna it almost made me not
want to fly one. Not much holding them on. Rational or not, I feel
better in turb in my Mooney knowing the entire cabin is sitting on the
one piece wing.

-Robert

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

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.

What is "double shear" and "single shear"?

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.

Jose wrote:

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.


What is "double shear" and "single shear"?

It refers to the number of planes in shear. Think of the rivet in a
scissors. There is one shear plane where the two halves of the scissors
meet and are held together by the pin/rivet.

Now think of a sandwich of three pieces of metal held together with a
bolt or pin or rivet. There are now two planes that are in shear and
thus you have twice as much shear resistance of the outer two pieces of
metal are pulled one direction and the middle piece is pulled another
direction.


Matt

Matt Whiting wrote:
Jose wrote:

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.


What is "double shear" and "single shear"?

It refers to the number of planes in shear. Think of the rivet in a
scissors. There is one shear plane where the two halves of the scissors
meet and are held together by the pin/rivet.

Now think of a sandwich of three pieces of metal held together with a
bolt or pin or rivet. There are now two planes that are in shear and
thus you have twice as much shear resistance of the outer two pieces of
metal are pulled one direction and the middle piece is pulled another
direction.


Matt

Here's a good illustration/animation:
http://www.ijee.dit.ie/OnlinePapers/...ted_double.htm


--
Mike

Matt Whiting wrote:


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

That's right. The 70% figure refers to single shear.

I made a mistake on the Grade 8 bolt head marking. It has six
radial marks, not five. Five is a Grade 7, not a common bolt. The
grades go clear to Grade 16, IIRC.

Dan

Aircraft grade bolt have many standards, more to do with
heat-treating and plating and tolerances on the thread and
shank fit and finish. Aircraft hardware is a detailed
study all to itself.



wrote in message
oups.com...
|
| Matt Whiting wrote:
|
|
| 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
|
| That's right. The 70% figure refers to single shear.
|
| I made a mistake on the Grade 8 bolt head marking.
It has six
| radial marks, not five. Five is a Grade 7, not a common
bolt. The
| grades go clear to Grade 16, IIRC.
|
| Dan
|