Senna
Well-Known Member
After much thought and number crunching I've decided to design and build a carbon composite spar for an ultralight I've had under construction for some time. The original spar design called for sitka spruce/ply and was engineered for a +3.5 g load rating. I actually constructed the spars as designed and have the center section complete with nose ribs, sheeting, main spar, mid ribs, rear spar, trailing edge ribs, and trailing edge. Unfortunately the outer spars were damaged during one of my many moves during this long building process.
I became enamored with this ultralight design way back in the late '80's after seeing it in an issue of Sport Aviation (I don't recall the issue). Actually in the photograph there were two of this particular ultralight parked on the grass side by side. Pod fuselage with boom, V-tail, tricycle gear, cantilevered wing, & pusher engined. I ordered and received plan set #340.
Over the years I have worked in fits and starts on this ultralight. I'm about to begin again. With the advancement of technology and materials... carbon fiber has become not only attractive but affordable. A recent discovery (a discovery for me anyway... as this product has been available for several years) has renewed my interest in completing and flying my plane. I found a mention of a carbon fiber pultruded rod called Graphlite™ during one of my many sessions surfing the Internet. I came across this material while viewing and reading of the construction of the Wes Whitehurst CARBON MONARCH on Jim Marske's web site. Marske has a link at the bottom right on his home page that took me to a paper he had written extolloing this Graphlite™ rod. If interested... you can read it here...
http://www.continuo.com/marske/carbon/carbon.htm
I first thought to incorporate the carbon rod into the original spruce spar by epoxying several of them in saw kerfs cut into the upper and lower spar caps. Once constructed I intended to proof this modification by statically load testing the spar. I began thinking about how I would conduct this necessary proofing... the rig that would be required... the method of loading the spar... the amount of weight for specific g loadings. It was while working with the numbers that I came to the conclusion that the original design, while benefiting from the incorporation of the carbon rods, would not take enough advantage of the tensile and compressive qualities the carbon possesses. I decided to completely scrap the idea of a spruce/carbon modified spar.
So... I'm embarking on a new adventure. One of exploration of an exciting product that has amazing structural qualities. My intent is now to engineer, design & construct a carbon main spar for my ultralight.
A spar mold for layup and vacuum bagging will be the first item of order. Since the original spar dimensions will be used... I'll have need of a 12 foot X 9-1/2" X 3/4" form to layup the new outer panel spars. The following drawing is the approach I plan to take.
More as it happens...
Senna
I became enamored with this ultralight design way back in the late '80's after seeing it in an issue of Sport Aviation (I don't recall the issue). Actually in the photograph there were two of this particular ultralight parked on the grass side by side. Pod fuselage with boom, V-tail, tricycle gear, cantilevered wing, & pusher engined. I ordered and received plan set #340.
Over the years I have worked in fits and starts on this ultralight. I'm about to begin again. With the advancement of technology and materials... carbon fiber has become not only attractive but affordable. A recent discovery (a discovery for me anyway... as this product has been available for several years) has renewed my interest in completing and flying my plane. I found a mention of a carbon fiber pultruded rod called Graphlite™ during one of my many sessions surfing the Internet. I came across this material while viewing and reading of the construction of the Wes Whitehurst CARBON MONARCH on Jim Marske's web site. Marske has a link at the bottom right on his home page that took me to a paper he had written extolloing this Graphlite™ rod. If interested... you can read it here...
http://www.continuo.com/marske/carbon/carbon.htm
I first thought to incorporate the carbon rod into the original spruce spar by epoxying several of them in saw kerfs cut into the upper and lower spar caps. Once constructed I intended to proof this modification by statically load testing the spar. I began thinking about how I would conduct this necessary proofing... the rig that would be required... the method of loading the spar... the amount of weight for specific g loadings. It was while working with the numbers that I came to the conclusion that the original design, while benefiting from the incorporation of the carbon rods, would not take enough advantage of the tensile and compressive qualities the carbon possesses. I decided to completely scrap the idea of a spruce/carbon modified spar.
So... I'm embarking on a new adventure. One of exploration of an exciting product that has amazing structural qualities. My intent is now to engineer, design & construct a carbon main spar for my ultralight.
A spar mold for layup and vacuum bagging will be the first item of order. Since the original spar dimensions will be used... I'll have need of a 12 foot X 9-1/2" X 3/4" form to layup the new outer panel spars. The following drawing is the approach I plan to take.
More as it happens...
Senna
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