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Default building jeep frame

Jim Stewart wrote:
John D. wrote:
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:

"Bill McKee" wrote in message
m...
"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very
well.
3400# boat. The Covette has an aluminum frame as well as the
Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex
should
not be a problem.

Boat trailers are rarely twisted the way that off-road vehicles
routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with
your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill
effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)
Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple times. :) And boat trailers are regularly towed over
uneven ground.
With three points taking out the loads -- hitch and suspension
supports, which generally are paired but close -- there is no
significant torsional load on a boat trailer. It's all simple
bending. You can deal with that, but if you towed your boat 100% of
the time, I think you'd develop fatigue problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear
panels. The subframes resolve their loads in three dimensions. There
isn't much flexing there.

The same applies to aircraft, which often are near-monocoque. If
they flex, you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


For what it's worth, I was told that the fuselage
skin on a B-52 was unwrinkled until they started
flying them at 100ft off the ground at 500mph or
something...


I can't vouch for the flying condition as I haven't seen a flying B52
that close, but the one parked at Boeing in Wichita around 1981-2
matched the John D description nicely, the wings drooped and the sides
were puckered in the parked configuration. IIRC the angle of the pucker
was mirrored either side of the wing indicating the direction of the
stresses in the panels due to the loadings when on the ground.
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Default building jeep frame

On Feb 28, 2:52*pm, mark wrote:
My original jeep CJ-7 frame has rusted out and I was thinking of
building a new one from aluminum. Would 2 X 4 X 1/4 *wall (if that is
even available) box tubing have the equivalent strength of the stock
1/8" wall steel frame? I would like aluminum because it will last
forever, no need of any paints etc..., very easy to work with and
cheaper than building a steel one and having it galvanized. My second
choice would be stainless 1/8" box tubing.


How old is your jeep? And after you put a new frame in it, how long
will you want to keep it? The thought being that the original frame
lasted X years. How long you want to keep it might be less than X
years.

Dan

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Default building jeep frame

On Tue, 02 Mar 2010 10:31:16 -0800, Jim Stewart
wrote:

John D. wrote:
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:

"Bill McKee" wrote in message
m...
"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.

Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)
Hell, I raced a vette, steel chassis, and it got to rock clrawing a couple
times. :) And boat trailers are regularly towed over uneven ground.
With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that, but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they flex,
you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


For what it's worth, I was told that the fuselage
skin on a B-52 was unwrinkled until they started
flying them at 100ft off the ground at 500mph or
something...


The B-52 H's that I worked on at Barksdale AFB certainly all had
wrinkles and frankly I doubt very much that the average B-52 was ever
flown at 500 MPH a hundred feet off the ground as it was deployed by
SAC, except for the "iron bomb" aircraft in Vietnam, as a high
altitude nuclear weapon delivery system.

In addition the fuel consumption would be astronomical under those
conditions as during a normal nuclear loaded mission first refueling
was very shortly after take-off, essentially as soon as the aircraft
reached cruising altitude, as so much fuel was burned getting off the
ground and climbing to altitude that the un-refueled range would be
(for a B-52) extremely limited.


John D.
(johnbslocombatgmaildotcom)
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Posts: 80
Default building jeep frame

On Mar 2, 4:38*pm, " wrote:
On Feb 28, 2:52*pm, mark wrote:

My original jeep CJ-7 frame has rusted out and I was thinking of
building a new one from aluminum. Would 2 X 4 X 1/4 *wall (if that is
even available) box tubing have the equivalent strength of the stock
1/8" wall steel frame? I would like aluminum because it will last
forever, no need of any paints etc..., very easy to work with and
cheaper than building a steel one and having it galvanized. My second
choice would be stainless 1/8" box tubing.


How old is your jeep? *And after you put a new frame in it, how long
will you want to keep it? * The thought being that the original frame
lasted X years. *How long you want to keep it might be less than X
years.

* * * * * * * * * * * * * * * * * * * * * * * Dan


It is 25 year old now and I want to rebuild it. I have been down the
road of sand blasting, metal prep, epoxy paints, polyurethane coatings
and as far as I am concerned nothing lasts when the roads are salted
in the winter and you live on an island surrounded by salt water. If I
am going to rebuild it and pass it down to my kids someday I am going
to do it in a way that it will last and not need to be done again. I
already have a fiberglass body. I have built aluminum aquaculture
cranes, and boats which see much more stress than a jeep frame will
ever see. If my original question was if you can build aluminum cranes
I can only imagine what the answers would be. As for the torsional
flexing, I don't think that exists, sure a frame by itself will flex
but when bolted to a body how could it flex and all body seems and
lines remain constant. A fiberglass body has no flex and it is bolted
to the frame. For the last 10 years my original frame has been so thin
you could break through it with a hammer in places and it is still
holding up, a 1/4" wall aluminum box frame has to be stronger than
that.
  #45   Report Post  
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Default building jeep frame

On Tue, 2 Mar 2010 09:02:48 -0500, "Ed Huntress"
wrote:


"John D." wrote in message
.. .
On Tue, 2 Mar 2010 02:28:52 -0500, "Ed Huntress"
wrote:


"John D." wrote in message
...
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:


"Bill McKee" wrote in message
news:qZ6dnaBKsPYVoxHWnZ2dnUVZ_uudnZ2d@earthli nk.com...

"RAMĀ³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very
well.
3400# boat. The Covette has an aluminum frame as well as the
Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex
should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles
routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with
your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill
effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)

Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple
times. :) And boat trailers are regularly towed over uneven ground.

With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant
torsional
load on a boat trailer. It's all simple bending. You can deal with that,
but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear
panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they
flex,
you die.

Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


John D.
(johnbslocombatgmaildotcom)

I don't know what the structure of a B-52 looks like, John, but it must be
far removed from a true monocoque. If a monocoque's skin wrinkled in
compression, all integrity would be gone, and it would completely
collapse.

The wings contain spars -- the skin is stressed in tension but takes no
compressive loads. That's stressed-skin but not monocoque. Most metal
aircraft wings are made like that.

I was referring to the fuselage, of which there are many different
designs.
As far back as the British Mosquito bomber of WWII, some aircraft have had
near-monocoque designs, which depend on the skin (which sometimes is cored
sandwiches, as on the Mosquito, and not a single sheet) to handle tensile,
compression, and shear loads. As you approach a true monocoque, any
stringers and ribs are there to help keep the skin's shape, rather than to
directly take out the major loads.


The only true monocoque airplane structure that I have seen is various
light aircraft and even then it is from the rear of the cockpit back
to the tail skid. The B-52 forward section is not a pure monocoque as
there is substantial structure to built the "two deck" upper and lower
areas so there are various formers and bearers but I suspect that the
skin does support a substantial amount of the load.

Are you sure that the Mosquito had a "cored" structure? I thought it
was cold molded - just layers of veneer glued together.


IIRC, it's wood veneer skins over an end-grain balsa core. It did have
bulkheads to maintain the fuselage's shape.



The "Balsa Bomber"


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Posts: 10
Default building jeep frame

On Tue, 2 Mar 2010 18:25:38 -0800 (PST), mark
wrote:

On Mar 2, 4:38*pm, " wrote:
On Feb 28, 2:52*pm, mark wrote:

My original jeep CJ-7 frame has rusted out and I was thinking of
building a new one from aluminum. Would 2 X 4 X 1/4 *wall (if that is
even available) box tubing have the equivalent strength of the stock
1/8" wall steel frame? I would like aluminum because it will last
forever, no need of any paints etc..., very easy to work with and
cheaper than building a steel one and having it galvanized. My second
choice would be stainless 1/8" box tubing.


How old is your jeep? *And after you put a new frame in it, how long
will you want to keep it? * The thought being that the original frame
lasted X years. *How long you want to keep it might be less than X
years.

* * * * * * * * * * * * * * * * * * * * * * * Dan


It is 25 year old now and I want to rebuild it. I have been down the
road of sand blasting, metal prep, epoxy paints, polyurethane coatings
and as far as I am concerned nothing lasts when the roads are salted
in the winter and you live on an island surrounded by salt water. If I
am going to rebuild it and pass it down to my kids someday I am going
to do it in a way that it will last and not need to be done again. I
already have a fiberglass body. I have built aluminum aquaculture
cranes, and boats which see much more stress than a jeep frame will
ever see. If my original question was if you can build aluminum cranes
I can only imagine what the answers would be. As for the torsional
flexing, I don't think that exists, sure a frame by itself will flex
but when bolted to a body how could it flex and all body seems and
lines remain constant. A fiberglass body has no flex and it is bolted
to the frame. For the last 10 years my original frame has been so thin
you could break through it with a hammer in places and it is still
holding up, a 1/4" wall aluminum box frame has to be stronger than
that.



A non-rusting jeep at:

http://www.flickr.com/photos/16916080@N05/3359404548/

I've seen these things up close and they are as pretty as the picture.


John D.
(johnbslocombatgmaildotcom)
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