Tweet
FINISHED TAIL WIRE.JPG
I found the price on the Steen wires to be a bit staggering so with considerable conversation with Bob and a local aerospace machine shop I produced my tail wires at about a cost of $70/wire, this would drop even further if I had a quantity to produce. As background Bob turns a piece of 1/4" 4130 down to .200" on a lathe by progressively indexing it, a slow process. I took raw 4130 and centerless ground it down to .226" which is the root diameter of a rolled 1/4"-28 thread. I then set the wires out to the aerospace guys who rolled left and right hand class 3A threads on each end. I discussed the .226" diameter with Bob and he was OK with it. The smaller the diameter the higher the natural frequency of vibration so small is beautiful. That said Bob says there are many flying airplanes with 1/4" wires and cut threads. The aerospace vendor says that keeping the diameter of .226" or the root diameter of the thread is their standard practice for a 1/4"-28 threads. They made this one set as a bit of a favor since I knew the owner as they generally only produce several hundred wires at a time. A picture is attached, they are a thing of beauty. Obviously they will need to be painted to prevent corrosion but a coat of silver would look good. A group buy could possibly get prices down in the $50/wire range. For your information American Champion uses 3/16" tailwires even on their full acrobatic airplanes. They use 316lL Stainless. Stainless would have a lower fatigue strength than 4130 but the Citabria line has been made this way for many years. More in depth engineering would be required to move to a 3/16" wire so I will leave that alone for now.
I found the price on the Steen wires to be a bit staggering so with considerable conversation with Bob and a local aerospace machine shop I produced my tail wires at about a cost of $70/wire, this would drop even further if I had a quantity to produce. As background Bob turns a piece of 1/4" 4130 down to .200" on a lathe by progressively indexing it, a slow process. I took raw 4130 and centerless ground it down to .226" which is the root diameter of a rolled 1/4"-28 thread. I then set the wires out to the aerospace guys who rolled left and right hand class 3A threads on each end. I discussed the .226" diameter with Bob and he was OK with it. The smaller the diameter the higher the natural frequency of vibration so small is beautiful. That said Bob says there are many flying airplanes with 1/4" wires and cut threads. The aerospace vendor says that keeping the diameter of .226" or the root diameter of the thread is their standard practice for a 1/4"-28 threads. They made this one set as a bit of a favor since I knew the owner as they generally only produce several hundred wires at a time. A picture is attached, they are a thing of beauty. Obviously they will need to be painted to prevent corrosion but a coat of silver would look good. A group buy could possibly get prices down in the $50/wire range. For your information American Champion uses 3/16" tailwires even on their full acrobatic airplanes. They use 316lL Stainless. Stainless would have a lower fatigue strength than 4130 but the Citabria line has been made this way for many years. More in depth engineering would be required to move to a 3/16" wire so I will leave that alone for now.
Comment