Fuselage building questions
Posted: Fri Feb 17, 2012 9:02 pm
Sorry for the following big dump. I should trickle this stuff out on the
list, one topic at a time. Anyway, here goes...
I am at the point where I am to begin attaching the tailcone to the cabin.
The manual told me to rivet the bottom tailcone skin to the cabin at this
time, and apparently leaves the sides and top for attachment at some later
time (which I haven't identified in the manual yet). I decided to not rivet
the bottom until all four sides are ready to rivet so that I can properly
scotchbrite and chromate everything and rivet wet as is recommended. This
sound familiar to anyone?
I am proceeding with the corner wraps. Anyone have any suggestions for
forming the piece that transitions from the rear of the cabin to the first
corner wrap? The manual says if you don't have a shrinker/stretcher (and I
don't) that it can be formed by hanging the piece over the edge of the table
and tapping it down with a large wooden dowel or even a baseball bat. I
tried to picture how that could be done and couldn't figure out how that
would work. Am I going to need a shrinker/stretcher for more stuff later?
If so, I guess I'll fork out the bucks for a tool I probably won't ever use
again after this project. By the way, I can see how the shrinker works on
the edge of a piece like a rib, but are those little jaws applied to a big
piece like this one to tighten up the curved part to match the curve of the
corner wrap. (Obvious I've never used one, eh?)
I am thinking about removing the part of the left side skin on the tailcone
where the cargo door will go now to make attaching the angle brackets/shear
webs to the bottom tailcone skin easier. The manual has you waiting until
much later to remove the side skin at the cargo door area. Does this sound
familiar to anyone? Any traps here?
I can't figure out what's to prevent a twist from developing in the entire
tailcone section while I continue drilling and adding stuff like corner
wraps. I keep an eye on it as best I can by eyeballing, taking measurements
up from the table, and such, but I still worry that my vertical stabilizer
will end up tilted to one side or the other. I can't see what I could do to
prevent it anyway since there's so much stuff prepunched. Am I worrying
about nothing?
I reviewed my Fletcher Aircraft Handbook and it gives the maximum amount of
material that can be removed with a ream. Then I checked the numbered,
letter size, and fractional bits to see what bit to use prior to reaming
holes such as 5/16, 7/16, and 1/2 inch holes that are common on the SR.
None of the available bits got me close enough based on the handbook's
"maximum amount of material to be removed with a ream". What's up with
that?
Lastly, I noticed on Hartzell's website that they don't recommend using
their propellors on auto engine conversions because, and I quote "we do not
endorse the use of Hartzell propellers on non-certified engines due to the
lack of demonstrated engine/propeller vibrational compatibility". This is a
cause for concern since I had hoped to use a constant speed, three blade
prop with a Chevy LS-1 conversion using a CAM500 PSRU. Despite this
warning, the Hartzell website has a strong Kitplane section. They just want
you to use known engine/prop combinations.
Mike Kimball
SR #044
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list, one topic at a time. Anyway, here goes...
I am at the point where I am to begin attaching the tailcone to the cabin.
The manual told me to rivet the bottom tailcone skin to the cabin at this
time, and apparently leaves the sides and top for attachment at some later
time (which I haven't identified in the manual yet). I decided to not rivet
the bottom until all four sides are ready to rivet so that I can properly
scotchbrite and chromate everything and rivet wet as is recommended. This
sound familiar to anyone?
I am proceeding with the corner wraps. Anyone have any suggestions for
forming the piece that transitions from the rear of the cabin to the first
corner wrap? The manual says if you don't have a shrinker/stretcher (and I
don't) that it can be formed by hanging the piece over the edge of the table
and tapping it down with a large wooden dowel or even a baseball bat. I
tried to picture how that could be done and couldn't figure out how that
would work. Am I going to need a shrinker/stretcher for more stuff later?
If so, I guess I'll fork out the bucks for a tool I probably won't ever use
again after this project. By the way, I can see how the shrinker works on
the edge of a piece like a rib, but are those little jaws applied to a big
piece like this one to tighten up the curved part to match the curve of the
corner wrap. (Obvious I've never used one, eh?)
I am thinking about removing the part of the left side skin on the tailcone
where the cargo door will go now to make attaching the angle brackets/shear
webs to the bottom tailcone skin easier. The manual has you waiting until
much later to remove the side skin at the cargo door area. Does this sound
familiar to anyone? Any traps here?
I can't figure out what's to prevent a twist from developing in the entire
tailcone section while I continue drilling and adding stuff like corner
wraps. I keep an eye on it as best I can by eyeballing, taking measurements
up from the table, and such, but I still worry that my vertical stabilizer
will end up tilted to one side or the other. I can't see what I could do to
prevent it anyway since there's so much stuff prepunched. Am I worrying
about nothing?
I reviewed my Fletcher Aircraft Handbook and it gives the maximum amount of
material that can be removed with a ream. Then I checked the numbered,
letter size, and fractional bits to see what bit to use prior to reaming
holes such as 5/16, 7/16, and 1/2 inch holes that are common on the SR.
None of the available bits got me close enough based on the handbook's
"maximum amount of material to be removed with a ream". What's up with
that?
Lastly, I noticed on Hartzell's website that they don't recommend using
their propellors on auto engine conversions because, and I quote "we do not
endorse the use of Hartzell propellers on non-certified engines due to the
lack of demonstrated engine/propeller vibrational compatibility". This is a
cause for concern since I had hoped to use a constant speed, three blade
prop with a Chevy LS-1 conversion using a CAM500 PSRU. Despite this
warning, the Hartzell website has a strong Kitplane section. They just want
you to use known engine/prop combinations.
Mike Kimball
SR #044
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