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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Fluted Bartlein vs Proof Research sendero contours
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<blockquote data-quote="Pdvdh" data-source="post: 1427370" data-attributes="member: 4191"><p>Correct. More heat would travel further along the axis of the barrel, toward each end, if the barrel is wrapped with insulating media compared to a non-insulated barrel. The magnitude of the heat conductance (flux) in the differing directions through the differing materials is where it gets complicated. I can't tell you how long it will take for the heat to conduct to the ends of your CF wrapped barrel, sufficiently for you to feel it with your hand. But it will take some time whether the barrel is insulated or not. There are too many variable factors, some being the number of shots fired and the rate at which they're fired, the mass / contour of the steel core of the CF wrapped barrel, the number of grains of powder burnt and the total BTUs of heat released internal to the bore by each cartridge, etc... Makes it impossible, in my opinion, to draw any conclusion from the temperature feel test. Bring an identical contoured 100% steel barrel to the testing grounds, fire both rifles at the same rate with the same load with a sufficient number of rounds fired, and then you can maybe draw some conclusion on the CF barrel compared to the steel barrel. Such a test minimizes the affecting factors, since both barrels are put through similar conditions over a similar length of time.</p><p></p><p>I tossed out the hot/cold feel test to get members to think about the consequences of conductive heat flow in a practical common sense way that we can sense by touch.</p><p>However there's nothing more definite and definitive on the conductive rate of heat transfer than the thermal conductivity coefficients of the CF wrap and barrel steel. We now have those values for both materials. It's a done deal. End of story. I wouldn't spend a lot of time trying to contest the science with a touch test. More futile than swimming against the tide in Cook Inlet, with 25+foot tides.</p><p></p><p>The other heat transfer property that was bandied about by the CF barrel manufacturer is used to predict/calculate instantaneous, very short term heat transfer rates. From my research, it has benefits of application in circumstances of very temporary/transient/changing temperature boundaries and swings in temperature. That's termed non-steady state temperature conditions/boundaries in the world of science. I'm curious what time duration qualifies under that engineer's definition of instantaneous. Because before the CF wrap can conduct any heat at all, the heat must first be transferred across the steel barrel core. After the combusting gasses release their heat to the lining of the bore, the steel bore must next conduct that heat radially to the carbon wrap across the radial thickness of the steel core. At the same time, some of that heat is being absorbed by the steel due to the heat capacity of steel (the quantity of heat energy stored in the steel for each degree rise in temperature). Does this border on instantaneous heat transfer? Applying that "instantaneous" coefficient to represent the rate of heat transfer in the carbon on a carbon wrapped rifle barrel is a complete misapplication of that coefficient. There's nothing we can do about short term heating and heat flux into the walls of the bore, other than not firing the gun. Heat is released and damage occurs with each round fired. We can reduce the damage to the steel bore per round fired, and increase bore life, by not firing successive rounds while the surface of the bore is already pre-heated from the prior round fired. Firing at rapid rates ensures the bore surface temperatures will increase higher than with the prior round, because the bore surface temperature is elevated with each round fired. So we can't avoid the instantaneous flash heat transfer to the bore surface. We can exert control over the bore surface temperature before touching off the next round and exposing the bore to another heat cycle. We have some ability to control how hot the bore/barrel become during repetitive fire. And this is a close approximation to maintaining an upper temperature inside the bore, and maintaining steady state-like heat transfer conditions. Holding the barrel temperature to "reasonable", not too high temperatures. The proper coefficient for steady state heat transfer is termed "thermal conductivity coefficient". Which is clearly very different than the fairy tale coefficient. Is there anyone with a CF barrel that really senses conductive heat transfer through their CF wrap at a rate 1000 times greater than heat conduction thru one of their steel barrels? Heat transferred from the bore to the surface at such an amazingly increased rate compared to steel. I'd think you'd blister your skin after 5 -10 consecutive shots. Would require a heat shield to prevent 3rd degree burns. That's what the fairy tale coefficient predicts, and that's how some common sense can identify its misapplication in promoting fabulous heat transfer rates thru CF wrap.</p><p></p><p>If the entire barrel, including the bore, were constructed of 100% CF, then the fairy tale coefficient application might begin to have some application. But CF barrels aren't 100% CF. They still have the plain-Jane steel core.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1427370, member: 4191"] Correct. More heat would travel further along the axis of the barrel, toward each end, if the barrel is wrapped with insulating media compared to a non-insulated barrel. The magnitude of the heat conductance (flux) in the differing directions through the differing materials is where it gets complicated. I can't tell you how long it will take for the heat to conduct to the ends of your CF wrapped barrel, sufficiently for you to feel it with your hand. But it will take some time whether the barrel is insulated or not. There are too many variable factors, some being the number of shots fired and the rate at which they're fired, the mass / contour of the steel core of the CF wrapped barrel, the number of grains of powder burnt and the total BTUs of heat released internal to the bore by each cartridge, etc... Makes it impossible, in my opinion, to draw any conclusion from the temperature feel test. Bring an identical contoured 100% steel barrel to the testing grounds, fire both rifles at the same rate with the same load with a sufficient number of rounds fired, and then you can maybe draw some conclusion on the CF barrel compared to the steel barrel. Such a test minimizes the affecting factors, since both barrels are put through similar conditions over a similar length of time. I tossed out the hot/cold feel test to get members to think about the consequences of conductive heat flow in a practical common sense way that we can sense by touch. However there's nothing more definite and definitive on the conductive rate of heat transfer than the thermal conductivity coefficients of the CF wrap and barrel steel. We now have those values for both materials. It's a done deal. End of story. I wouldn't spend a lot of time trying to contest the science with a touch test. More futile than swimming against the tide in Cook Inlet, with 25+foot tides. The other heat transfer property that was bandied about by the CF barrel manufacturer is used to predict/calculate instantaneous, very short term heat transfer rates. From my research, it has benefits of application in circumstances of very temporary/transient/changing temperature boundaries and swings in temperature. That's termed non-steady state temperature conditions/boundaries in the world of science. I'm curious what time duration qualifies under that engineer's definition of instantaneous. Because before the CF wrap can conduct any heat at all, the heat must first be transferred across the steel barrel core. After the combusting gasses release their heat to the lining of the bore, the steel bore must next conduct that heat radially to the carbon wrap across the radial thickness of the steel core. At the same time, some of that heat is being absorbed by the steel due to the heat capacity of steel (the quantity of heat energy stored in the steel for each degree rise in temperature). Does this border on instantaneous heat transfer? Applying that "instantaneous" coefficient to represent the rate of heat transfer in the carbon on a carbon wrapped rifle barrel is a complete misapplication of that coefficient. There's nothing we can do about short term heating and heat flux into the walls of the bore, other than not firing the gun. Heat is released and damage occurs with each round fired. We can reduce the damage to the steel bore per round fired, and increase bore life, by not firing successive rounds while the surface of the bore is already pre-heated from the prior round fired. Firing at rapid rates ensures the bore surface temperatures will increase higher than with the prior round, because the bore surface temperature is elevated with each round fired. So we can't avoid the instantaneous flash heat transfer to the bore surface. We can exert control over the bore surface temperature before touching off the next round and exposing the bore to another heat cycle. We have some ability to control how hot the bore/barrel become during repetitive fire. And this is a close approximation to maintaining an upper temperature inside the bore, and maintaining steady state-like heat transfer conditions. Holding the barrel temperature to "reasonable", not too high temperatures. The proper coefficient for steady state heat transfer is termed "thermal conductivity coefficient". Which is clearly very different than the fairy tale coefficient. Is there anyone with a CF barrel that really senses conductive heat transfer through their CF wrap at a rate 1000 times greater than heat conduction thru one of their steel barrels? Heat transferred from the bore to the surface at such an amazingly increased rate compared to steel. I'd think you'd blister your skin after 5 -10 consecutive shots. Would require a heat shield to prevent 3rd degree burns. That's what the fairy tale coefficient predicts, and that's how some common sense can identify its misapplication in promoting fabulous heat transfer rates thru CF wrap. If the entire barrel, including the bore, were constructed of 100% CF, then the fairy tale coefficient application might begin to have some application. But CF barrels aren't 100% CF. They still have the plain-Jane steel core. [/QUOTE]
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