Rivets vs Welding

I've not fully studied aircraft construction techniques so forgive me if the
answer to this is obvious. I've noted that most(if not all) aircraft made
with aluminium airframes seem to be riveted rather than welded. I'm not
sure about aircraft with composite or fibreglass skins so I won't be
dogmatic on that point, but anyway.

Is there a reason why aircraft would be riveted rather than welded together,
particularly on the airframe, not the skin? I would have imagined that
welding would produce a stronger join, although it may be harder or
impossible to disassemble if needed. Thanks,

David

David Findlay wrote:

snip

Is there a reason why aircraft would be riveted rather than welded
together, particularly on the airframe, not the skin? I would have
imagined that welding would produce a stronger join, although it may be
harder or impossible to disassemble if needed. Thanks,

One key point is QC.

With the rivets a Al batch of a known alloy is turned into a bazillion
rivets by a machine. A small number of these rivets are tested to confirm
the batch of rivets is up to spec.

Using well understood and documented techniques a joint is designed for the
required stresses with x rows of rivets at y spacing etc. The joint is then
riveted.

QC on the joint itself merely requires visual examination, no fancy ND
techniques etc.

Routine inspection in service likewise is done by visual inspection.

--

regards

jc

LEGAL - I don't believe what I wrote and neither should you. Sobriety and/or
sanity of the author is not guaranteed

EMAIL - and are not valid email
addresses. news2x at perentie is valid for a while.

On Sat, 01 Jan 2005 17:36:39 +1100, jc wrote:

David Findlay wrote:

snip

Is there a reason why aircraft would be riveted rather than welded
together, particularly on the airframe, not the skin? I would have
imagined that welding would produce a stronger join, although it may be
harder or impossible to disassemble if needed. Thanks,

One key point is QC.

With the rivets a Al batch of a known alloy is turned into a bazillion
rivets by a machine. A small number of these rivets are tested to confirm
the batch of rivets is up to spec.

Using well understood and documented techniques a joint is designed for the
required stresses with x rows of rivets at y spacing etc. The joint is then
riveted.

QC on the joint itself merely requires visual examination, no fancy ND
techniques etc.

Routine inspection in service likewise is done by visual inspection.

and in service a stuffed rivet can be merely drilled out and replaced.
a cracked weld would probably result in expensive repair, or the
resorting to rivetted in place patches.

rivets may not be the best in an ideal world but they are practical
and result in almost infinitely repairable aircraft.

david something that bears consideration is that over the full life of
an aircraft every component will come to need repair as it wears out.
so every component needs to be got at, removed, replaced or repaired
and put back into service. rivets may be tedious but allow this to
occur. welded components may lead to an entire airframe sitting on the
tarmac or in a hangar while repairs to cracks are thought through and
attempted.

australia's macchi jet trainers have cast ring beams in the fuselage
to which the wings attach. cracks in these saw lots of downtime while
repairs were contemplated and eventually led to the scrapping of the
aircraft. ...which isnt good for repeat business.

Stealth Pilot
Australia.

david something that bears consideration is that over the full life of
an aircraft every component will come to need repair as it wears out.
so every component needs to be got at, removed, replaced or repaired
and put back into service. rivets may be tedious but allow this to
occur. welded components may lead to an entire airframe sitting on the
tarmac or in a hangar while repairs to cracks are thought through and
attempted.

I suppose part of that is to do with how long we operate aircraft. If
aircraft cost similiar to new cars and were similiar costs to maintain it
wouldn't matter if we threw out an airframe every 15-20 years, but at the
current costs it's rather impractical. Thanks,

David

David Findlay wrote:
=

david something that bears consideration is that over the full life o=
f
an aircraft every component will come to need repair as it wears out.=

so every component needs to be got at, removed, replaced or repaired
and put back into service. rivets may be tedious but allow this to
occur. welded components may lead to an entire airframe sitting on th=
e
tarmac or in a hangar while repairs to cracks are thought through and=

attempted.
=

I suppose part of that is to do with how long we operate aircraft. If
aircraft cost similiar to new cars and were similiar costs to maintain =
it
wouldn't matter if we threw out an airframe every 15-20 years, but at t=
he
current costs it's rather impractical. Thanks,
=

David

A century ago, people traveled by ship or train, both of which were held
together with rivets. Sometimes in the 1940's they both switched to
welding, and soon after the passengers switched to planes and busses,
both of which still use rivets. Coincidence? =

-- =

John Halpenny


A cluttered desk is the sign of a cluttered mind.
I=92m so glad my desk isn't empty.

John Halpenny wrote:

David Findlay wrote:

david something that bears consideration is that over the full life of
an aircraft every component will come to need repair as it wears out.
so every component needs to be got at, removed, replaced or repaired
and put back into service. rivets may be tedious but allow this to
occur. welded components may lead to an entire airframe sitting on the
tarmac or in a hangar while repairs to cracks are thought through and
attempted.

I suppose part of that is to do with how long we operate aircraft. If
aircraft cost similiar to new cars and were similiar costs to maintain it
wouldn't matter if we threw out an airframe every 15-20 years, but at the
current costs it's rather impractical. Thanks,

David


A century ago, people traveled by ship or train, both of which were held
together with rivets. Sometimes in the 1940's they both switched to
welding, and soon after the passengers switched to planes and busses,
both of which still use rivets. Coincidence?

Uh, yes. :-)


Matt