airplane construction

Robert M. Gary wrote:
Mike wrote:
Robert M. Gary wrote:
I'm guessing that's why there's wing struts How many bolts secure the
wings to the fuselage?

On the Cessna I don't remember how many "wing nuts" there were holding
the wing on, I just remember the very small area in which the wing
attaches to the body. There must be insane amounts of stress on that
small area of metal.

On the Mooney, there is but one single wing. The spar runs right under
the seats. No one has problems with wings coming off but the Mooney
design makes me more comfortable.

-Robert

The 172 has a 7/16" bolt on the front spar attach, and a 3/8" at
the rear, IIRC without going downstairs and looking it up. Both are in
double shear. The bolt is stronger than the aluminum fittings, and the
fittings are much stronger than they look or need to be. The airplane
is rated for 3.8g positive, with 150% design limits beyond that, and I
can't remember the last time I heard of a 172 shedding a wing unless
the pilot tried to fly through a thunderstorm, in which case he'd have
died anyway. The stabilizer is weaker than the wing in many light
aircraft.
The struts are connected with 1/2" bolts in double shear.

The Mooney's one-piece wing spar is made of many smaller
pieces, all held together with tiny rivets. No stronger than the 172, I
bet. The Mooney's POH should give a g rating for the airframe.

Which reminds me: a friend recently told me of an accident in
the Southeastern US where a new Commercial pilot flew a Monney into a
thunderboomer at night. They found the wreckage scattered far and wide,
and the Mooney engineers that examined the bits and pieces estimated
that the aircraft experienced an upward acceleration of between 20 and
23 Gs. The passenger, complete with seat, went through the bottom of
the airplane and was found some distance behind the rest of the mess.
Even if the airplane had held together the occupants would have been
incapacitated or killed by the damage wrought by the acceleration.

Dan

wrote:
Robert M. Gary wrote:
Mike wrote:
Robert M. Gary wrote:

The 172 has a 7/16" bolt on the front spar attach, and a 3/8" at
the rear, IIRC without going downstairs and looking it up. Both are in
double shear. The bolt is stronger than the aluminum fittings, and the
fittings are much stronger than they look or need to be. The airplane
is rated for 3.8g positive, with 150% design limits beyond that, and I
can't remember the last time I heard of a 172 shedding a wing unless
the pilot tried to fly through a thunderstorm, in which case he'd have
died anyway. The stabilizer is weaker than the wing in many light
aircraft.

Agreed. I understand 172's are not falling from the sky, just an
emotional reaction to seeing what is actually holding the wings on. I
wonder what holds the wings on the C-177 if the struts old the wings on
the c-172.

The Mooney's one-piece wing spar is made of many smaller
pieces, all held together with tiny rivets. No stronger than the 172, I
bet. The Mooney's POH should give a g rating for the airframe.

The 3.8g limit you mention for the c-172 is just a function of the
certification category. Since the Mooney and the 172 share the same
category they are both 3.8g's with 150% minimum overdesign by
definition. Note sure what the actual structural limits are though. The
manufactors don't tell us the actual limits, just the certification
limits.

The Mooney is known for being amazingly strong though. Rememeber the
picture of the 201 coming off the line with several dozen people
standing on the wing? They flew that plane afterwards w/o problem. I
have a friend who survived a nasty accident in his 201 and credits the
steel tube cabin for saving his life.

Which reminds me: a friend recently told me of an accident in
the Southeastern US where a new Commercial pilot flew a Monney into a
thunderboomer at night. They found the wreckage scattered far and wide,
and the Mooney engineers that examined the bits and pieces estimated
that the aircraft experienced an upward acceleration of between 20 and
23 Gs. The passenger, complete with seat, went through the bottom of
the airplane and was found some distance behind the rest of the mess.
Even if the airplane had held together the occupants would have been
incapacitated or killed by the damage wrought by the acceleration.

Do you have a reference for this? A possible date range, the state if
happened in or something I can search on? I'd like to pull up the NTSB
on it.

-Robert

Robert M. Gary wrote:
wrote:
Robert M. Gary wrote:
Mike wrote:
Robert M. Gary wrote:

The 172 has a 7/16" bolt on the front spar attach, and a 3/8" at
the rear, IIRC without going downstairs and looking it up. Both are in
double shear. The bolt is stronger than the aluminum fittings, and the
fittings are much stronger than they look or need to be. The airplane
is rated for 3.8g positive, with 150% design limits beyond that, and I
can't remember the last time I heard of a 172 shedding a wing unless
the pilot tried to fly through a thunderstorm, in which case he'd have
died anyway. The stabilizer is weaker than the wing in many light
aircraft.

Agreed. I understand 172's are not falling from the sky, just an
emotional reaction to seeing what is actually holding the wings on. I
wonder what holds the wings on the C-177 if the struts old the wings on
the c-172.

The Mooney's one-piece wing spar is made of many smaller
pieces, all held together with tiny rivets. No stronger than the 172, I
bet. The Mooney's POH should give a g rating for the airframe.

The 3.8g limit you mention for the c-172 is just a function of the
certification category. Since the Mooney and the 172 share the same
category they are both 3.8g's with 150% minimum overdesign by
definition. Note sure what the actual structural limits are though. The
manufactors don't tell us the actual limits, just the certification
limits.

The Mooney is known for being amazingly strong though. Rememeber the
picture of the 201 coming off the line with several dozen people
standing on the wing? They flew that plane afterwards w/o problem. I
have a friend who survived a nasty accident in his 201 and credits the
steel tube cabin for saving his life.

Which reminds me: a friend recently told me of an accident in
the Southeastern US where a new Commercial pilot flew a Monney into a
thunderboomer at night. They found the wreckage scattered far and wide,
and the Mooney engineers that examined the bits and pieces estimated
that the aircraft experienced an upward acceleration of between 20 and
23 Gs. The passenger, complete with seat, went through the bottom of
the airplane and was found some distance behind the rest of the mess.
Even if the airplane had held together the occupants would have been
incapacitated or killed by the damage wrought by the acceleration.

Do you have a reference for this? A possible date range, the state if
happened in or something I can search on? I'd like to pull up the NTSB
on it.

-Robert

Last summer, Texas/Louisiana neighborhood, I think. The
details were in the story, not the time and place.

Dan

wrote:
Robert M. Gary wrote:
Last summer, Texas/Louisiana neighborhood, I think. The
details were in the story, not the time and place.

I'd like to see the actual report on that. I did a search from 1980-now
for fatals in any Mooney that includes the word "thunderstorm" and only
came up with 3, but none mention the pilot having left the aircraft.
This is what I found.
http://www.ntsb.gov/ntsb/brief2.asp?...FA032& akey=1

http://www.ntsb.gov/ntsb/brief2.asp?...FA116& akey=1

http://www.ntsb.gov/ntsb/brief.asp?e...14X36345&key=1

The only Mooney fatal I could find in the SE last summer was this one
http://www.ntsb.gov/ntsb/brief.asp?e...31X01061&key=1

Perhaps that's the one?? The report is only preliminary but doesn't
mention whether the pilot was with the aircraft or not.

-Robert

Robert M. Gary wrote:
wrote:
Robert M. Gary wrote:
Last summer, Texas/Louisiana neighborhood, I think. The
details were in the story, not the time and place.



The only Mooney fatal I could find in the SE last summer was this one
http://www.ntsb.gov/ntsb/brief.asp?e...31X01061&key=1

Perhaps that's the one?? The report is only preliminary but doesn't
mention whether the pilot was with the aircraft or not.

-Robert

That's likely it. The report gives no details whatever of the
condition of the wreckage; perhaps that's forthcoming.

Dan

wrote:
Robert M. Gary wrote:
Mike wrote:
Robert M. Gary wrote:
I'm guessing that's why there's wing struts How many bolts secure the
wings to the fuselage?
On the Cessna I don't remember how many "wing nuts" there were holding
the wing on, I just remember the very small area in which the wing
attaches to the body. There must be insane amounts of stress on that
small area of metal.

On the Mooney, there is but one single wing. The spar runs right under
the seats. No one has problems with wings coming off but the Mooney
design makes me more comfortable.

-Robert

The 172 has a 7/16" bolt on the front spar attach, and a 3/8" at
the rear, IIRC without going downstairs and looking it up. Both are in
double shear. The bolt is stronger than the aluminum fittings, and the
fittings are much stronger than they look or need to be. The airplane
is rated for 3.8g positive, with 150% design limits beyond that, and I
can't remember the last time I heard of a 172 shedding a wing unless
the pilot tried to fly through a thunderstorm, in which case he'd have
died anyway. The stabilizer is weaker than the wing in many light
aircraft.
The struts are connected with 1/2" bolts in double shear.

The Mooney's one-piece wing spar is made of many smaller
pieces, all held together with tiny rivets. No stronger than the 172, I
bet. The Mooney's POH should give a g rating for the airframe.

Which reminds me: a friend recently told me of an accident in
the Southeastern US where a new Commercial pilot flew a Monney into a
thunderboomer at night. They found the wreckage scattered far and wide,
and the Mooney engineers that examined the bits and pieces estimated
that the aircraft experienced an upward acceleration of between 20 and
23 Gs. The passenger, complete with seat, went through the bottom of
the airplane and was found some distance behind the rest of the mess.
Even if the airplane had held together the occupants would have been
incapacitated or killed by the damage wrought by the acceleration.

Dan


Thanks for the insight, Dan. I never knew that about the C172 (or should
I say high-wing?). Definitely learned a few more things today.


--
Mike