Carbon wrapped barrels are said to be able to dissipate heat faster than all steel barrels, so how does it do this if the surface of the barrel heats up slower / less than that of it's all steel counterpart, all while having a heat capacity (volumetric) lower than steel? If the heat is not being removed off the surface by air, and the epoxy/carbon fiber stores less energy per degree temperature rise, where is the heat going exactly? Convection (heat dissipation) only has to the do with the heat transfer coefficient of the fluid the object is transferring heat into and the temp difference between the object and the fluid. If the temperature of the barrel stays low on the outside, math says that very little heat is being dissipated. What am I missing?
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Carbon Wrapped Barrels - Heat Dissipation Question
- Thread starter lte82
- Start date
Guess you guys know more than the firearms engineers at Barrett and Proof. You should start your own company. To paraphrase the experts above it is plainly impossible for any material to radiate heat faster than any other material. And the corollary is with a given amount of heat to radiate the OD of the object is irrelevant because the object must reach a set temp before it starts to radiate heat.
Prove those new laws of physics you just invented and you won't have to start your own company, major universities will want to hire you to lead their physics departments.
On the other hand it might be wise to consider that a carbon fibre barrel of the same weight has a much larger circumference to radiate the heat from so it does not need to become as hot to radiate the same amount of heat. On My MRAD conversion barrels the CF .260 Remington barrel has a circumference of 4" and My steel .308 Barrel has a circumference of 2-7/8. So to me it makes sence that with a surface area more than 25% greater it could reach an equilibrium at a lower tempature for a given rate of fire. If the pitch fibers are much more thermally conductive and cool down much faster than steel as claimed then this would only lower the equilibrium tempature even farther as heat already disapated is gone.
Prove those new laws of physics you just invented and you won't have to start your own company, major universities will want to hire you to lead their physics departments.
On the other hand it might be wise to consider that a carbon fibre barrel of the same weight has a much larger circumference to radiate the heat from so it does not need to become as hot to radiate the same amount of heat. On My MRAD conversion barrels the CF .260 Remington barrel has a circumference of 4" and My steel .308 Barrel has a circumference of 2-7/8. So to me it makes sence that with a surface area more than 25% greater it could reach an equilibrium at a lower tempature for a given rate of fire. If the pitch fibers are much more thermally conductive and cool down much faster than steel as claimed then this would only lower the equilibrium tempature even farther as heat already disapated is gone.
It's thermodynamics 101 at any major university, and it's doubtful I would ever want to go to a university. I am a PE and own a consulting company, and my wife is a professor so I know enough to know that I don't want any part of that lol.
And yea, OD is irrelevant if there is no temperature difference. And no, the radiation difference would be a few watts due to surface area increase if that. Radiation is just not high enough to really even consider.
I'll take a stab at it. They cool down faster because there is less steel to store the heat. Same as an all steel barrel. A smaller profile barrel will cool fastert than a thicker one. They heat up faster but they cool faster also. The carbon and resin I think have little to do with heat dissipation. It does shield your hand and the surrounding air from the affects of the heated steel more though. Feels cooler, looks cooler through the scope. That's how I see it. I only took one physics class in college, but, I did stay at a Holiday Inn Express last night 
I don't care wether it is cooled by radiation, convection or conduction (because the principle is the same) with a larger surface area it will cool faster. As far as your "if there is not tempature difference" that's just nonsense, of course there is a tempature difference, it is just less because the principles already explained allow the heat to be dissapated more quickly and from a larger area.
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I've seen that graph from Proof before, and I've always had some questions about it. It states that it uses only external temperature data coupled with Fourier's Law, something that would require very accurate material characterization to be trusted. The problem is that, regardless of the proprietary resin used, transverse heat transfer in the fibers themselves is poor. If the entire barrel is actually cooling faster, I believe it has to do with carbon fiber's substantially higher longitudinal heat transfer coefficient. In that case there is a possibility that the heat is distributed more evenly along the length of the barrel (not concentrated in the chamber area), effectively increasing the heat transfer surface area.
In any case, ask me about this in three years. I'm about a month and a half away from starting a PhD where my dissertation will be on the thermo-mechanical analysis of composite barrels.
In any case, ask me about this in three years. I'm about a month and a half away from starting a PhD where my dissertation will be on the thermo-mechanical analysis of composite barrels.
My redneck engineering degree has always thought the carbon acts more as an insulator and keeps the heat in a barrel.
Imagine a thermos with 100° coffee inside and then the marketing team comes in and measures the outside temp of the thermos and graphs it.
Hey look consumer, barrel temp stays at 72°.
Viola, were awesome.
Imagine a thermos with 100° coffee inside and then the marketing team comes in and measures the outside temp of the thermos and graphs it.
Hey look consumer, barrel temp stays at 72°.
Viola, were awesome.
The Carbon Fiber moves the heat across a larger area... Steel barrels heat up from the chamber, the carbon fiber acts to move the heat down the entire length vs radiating at the source. There is a steel barrel underneath, it's pencil thin with nodes to attach the wrap and move things around. Unlike others, it's just not a straight steel barrel with the wrap touching the ends where it connects, but rather you have nodes underneath.
It's not a straight up insulator, as they can add things to the resin to help dissipate the heat.
The Aero Space side of Proof does work on Satellites and engines the majority of their technology is used around high heat in places that cannot be liquid cooled. I had a 2-hour presentation from the AeroSpace Ph.D. from their Dayton office explain it to me with the powerpoint. He alternated between the aerospace application and the applied barrel application.
You guys can guess all you want, it's not gonna change things, The barrels work as advertised.
It's not a straight up insulator, as they can add things to the resin to help dissipate the heat.
The Aero Space side of Proof does work on Satellites and engines the majority of their technology is used around high heat in places that cannot be liquid cooled. I had a 2-hour presentation from the AeroSpace Ph.D. from their Dayton office explain it to me with the powerpoint. He alternated between the aerospace application and the applied barrel application.
You guys can guess all you want, it's not gonna change things, The barrels work as advertised.
Not sure I agree with that statement, though I could be wrong. I would be interested in watching you pick up a steel barrel with your bare hands immediately after it was removed from a 2200 degree oven.
I'm not sure what you are trying to prove. I made that statment as a way to poke a little fun at previous posters who claim that CF barrels retain heat more than steel barrels, in the case of one previous poster the CF barrels do not conduct heat because the surface dies not get hot enough. I certianly have not said that I can pick up 2200 degree steel. If I were to attempt to "pick up a steel barrel with your bare hands immediately after it was removed from a 2200 degree oven" it would do sever injury to my hands. I have never caused you any harm, why do you wish to see me severly injured? I find your post offensive. Fuck you!
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I don't know about all this temperature stuff though I imagine Proof puts a bunch a money in it. My question is, if you bought 1 Proof barrel vs 2 Bartleins for same price.. would the Proof out shoot both Barts? How much better does a Proof shoot vs say a Bartlein that's a skinny contour to match the Proof's weight?
I don't know much about the science but I know from first hand experience that carbon fiber parts pulled from a hot oven become cool enough to touch a lot quicker than steel parts. It's not even close.
Carbon fiber parts suffer from far less heat distortion that steel parts too. As long as you stay within the heat tolorances of the resin, you have an incredibly dimensionally stable part with carbon fiber. The max temp with the heat cure epoxy resins I use is usually around 400 degrees.
Steel, like most metals, expands and contracts with changes in temperature. That's how old thermostats work - using a bi-metallic strip.
Carbon fiber is also a lighter, stronger and stiffer material than steel when it's made right. This isn't a debate or a matter of opinion. It's fact.
Carbon fiber parts suffer from far less heat distortion that steel parts too. As long as you stay within the heat tolorances of the resin, you have an incredibly dimensionally stable part with carbon fiber. The max temp with the heat cure epoxy resins I use is usually around 400 degrees.
Steel, like most metals, expands and contracts with changes in temperature. That's how old thermostats work - using a bi-metallic strip.
Carbon fiber is also a lighter, stronger and stiffer material than steel when it's made right. This isn't a debate or a matter of opinion. It's fact.
^^^What he said^^^ or asked, actully. I've been toying with the idea of getting one but the 'coolness' factor will only go so far. Some real world advantages with regards to barrel life would be useful.
Yep. Energy stored in an object, like a barrel, is a function of specific heat, mass, and temperature. Carbon fiber stores less energy by volume than steel given the same temperature, so the temperature drops at a faster rate (more or less) proportional to the difference in specific heat & mass. This is illustrated in the graph that proof shows. However the graph that Proof shows 1) has nothing to do with conduction, or whether or not their carbon fiber wrap conducts heat faster or slower than steel, 2) merely proves it has less stored energy than steel and 3) misapplies Fourier's law, as it has to do with conduction not convection.
https://www.google.com/patents/EP3039374A1
Proof's patent reads a lot differently than their marketing material, that's for sure. I also read through a ton of patents from Christensen, the US Army, Lockheed Martin, Magnum Research, etc and most agree that composite wraps are insulators, and Proof is the only one that has a composite wrap that is less of an insulator. Christensen even says the liner gets "very hot", and the Army suggests using something other than steel so the bore doesn't melt. And there is zero test data from any of these companies producing wrapped barrels that show otherwise...
Proof's patent reads a lot differently than their marketing material, that's for sure. I also read through a ton of patents from Christensen, the US Army, Lockheed Martin, Magnum Research, etc and most agree that composite wraps are insulators, and Proof is the only one that has a composite wrap that is less of an insulator. Christensen even says the liner gets "very hot", and the Army suggests using something other than steel so the bore doesn't melt. And there is zero test data from any of these companies producing wrapped barrels that show otherwise...
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The thing everyone is forgetting is
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Christensen has been doing it longer but with far less effort behind it. I have been to both factories, Proof, and Christensen and there is a big difference.
Christensen was just using turned downed Remington take off barrels, which were completely sub-par. Christensen's aero work is mainly on non-heat parts. Doors, Service Bays, Cowling components whereas Proof is in deep with engines and satellites that have to radiate heat without the ability to use liquid to cool it.
Christensen is a button pulled barrel and when I was there saw a ton of broken buttons. Proof is a rifle cut, so that helps with stress relieving. Proof laps twice, Christensen once.
Different ways of wrapping between the two also. While Christensen can wrap in a similar fashion, they choose to go in a different direction.
Christensen's gunsmithing side is much smaller than Proof as everything is wrapped up in their Aero division. There is a lot happening when it comes to the resins at Proof vs Christensen which just use the Aero stuff and keep their stuff in cold storage.
Under the wrap is different too... Proof is testing stuff that I never saw at Christensen. Proof's R&D department, as well as Engineering is much more extensive and they are constantly fiddling with stuff and measuring the results
I have an image but it keeps showing in thumbnail size, but trust me there is a huge difference between the two
Christensen was just using turned downed Remington take off barrels, which were completely sub-par. Christensen's aero work is mainly on non-heat parts. Doors, Service Bays, Cowling components whereas Proof is in deep with engines and satellites that have to radiate heat without the ability to use liquid to cool it.
Christensen is a button pulled barrel and when I was there saw a ton of broken buttons. Proof is a rifle cut, so that helps with stress relieving. Proof laps twice, Christensen once.
Different ways of wrapping between the two also. While Christensen can wrap in a similar fashion, they choose to go in a different direction.
Christensen's gunsmithing side is much smaller than Proof as everything is wrapped up in their Aero division. There is a lot happening when it comes to the resins at Proof vs Christensen which just use the Aero stuff and keep their stuff in cold storage.
Under the wrap is different too... Proof is testing stuff that I never saw at Christensen. Proof's R&D department, as well as Engineering is much more extensive and they are constantly fiddling with stuff and measuring the results
I have an image but it keeps showing in thumbnail size, but trust me there is a huge difference between the two
I think the nice people at NASA would disagree with you as well. The tiles on the shuttle, and well most vehicles that have to reenter the atmosphere with living meat inside, use materials that were specifically designed for heat transfer and dissipation. Things get pretty warm when you are swimming through the plasma that used to be air, at Mach 20+.
My concern with carbon wrapped barrels would be more with delamination of the composite due to heat rather than how they radiate the heat. Epoxy based composites like carbon fiber composites don't hold up so well under high temps. Mount a suppressor at the end of one of your carbon fiber barrels, and you have a potential recipe for disaster.
I think you may want to re-comprehend what he said.
I am not sure if this is relevant to the carbon used on barrels, but the bio char I use, pure carbon, has a guarantied analysis of 300sqft of surface area per gram.
The problem isn't with carbon. If your using something that is pure carbon than it is by definition not a composite. Composites include one or more materials to make a structure. You are right though, carbon does really well with heat. The epoxies they use to make carbon fiber composites on the other hand, not so much. I thought the OP was talking specifically about carbon fiber composite wrapped barrels.
You gave me the right and wrong definitions of a composite in two sentences. Just poking, obviously you know more than me here.
Biochar is an organic soil amendment. If I glued two pieces together, it would be a composite with a ton of surface area to dissipate heat. I know nothing about carbon barrels, and very little about the properties of carbon. I was just throwing it out there. i Know it works, i just always wonder about the, why?
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So folks will have a factual basis for comments regarding the Shuttle's Thermal Protective System.
Its primary intent is to serve as an insulator, and not as a conductor. Of particular note is the fact that the shuttle's reentry attitude creates an intentional shock wave, deflecting and redirection the greater majority of the compressive heating process away from the vehicle's surface.
In the midst of all the fact and conjecture in this topic, I pay particular attention to the information brought forth in LowLight's posts. He's been directly schooled on the subject, with specific reference to the barrels under discussion here. I think a thorough rereading of his posts might be beneficial.
Greg
Its primary intent is to serve as an insulator, and not as a conductor. Of particular note is the fact that the shuttle's reentry attitude creates an intentional shock wave, deflecting and redirection the greater majority of the compressive heating process away from the vehicle's surface.
In the midst of all the fact and conjecture in this topic, I pay particular attention to the information brought forth in LowLight's posts. He's been directly schooled on the subject, with specific reference to the barrels under discussion here. I think a thorough rereading of his posts might be beneficial.
Greg
I was trying to say, and I still think you are, both saying the same thing. He was making fun of people for thinking all materials dissipate heat at the same rate. Thats what I thought anyway. Then you said, "all things do dissipate heat at a different rate," to him.
What better way to shield from heat than to conduct it to a heat sink in a cooler area.
IMO it all boils down to: does the cost of these barrels justify themselves vs non wrapped barrels? I'm not saying they don't work or even care how they get it to work. I have read several post from those in the know and have them but other than the weight and " coolness" factor... do they shoot any better? Do they last any longer. No one has ever stated this in a side by side test. Folks will buy one try it say " I like mine or " mine shoots great" but at a cost of 2 to 1 doesn't make since if it doesn't justify the cost
Supercorndogs, I think you are correct, I think Tomcatfan has attributed to me the statement that I made to point out how foolish some previous posters statements were. I do think he is correct in assuming that the people who believe that "all materials dissapate heat at the same rate" Are wrong.
Further if I were to assume that Tomcatfan is not one of those weirdos who love male cats but rather someone who laments that the USN no longer has the ability to launch a Tomcat with a six pack of Phoenix missles. I agree that the USN needs a real fighter.
Lol. You are correct about the tomcat. The F-14 is why I am an aerospace engineer. It was the last of the Navy's true intercept/fighter aircraft. Now the DoD is all about jack of all trades, master of none type of aircraft. It sucks.
^^^^^^^What he said^^^^^^^^
The above is the point, as far as I'm concerned. "Coolness" ? OK, I'll agree. Weight factor. Turns a 16lb rifle to a 14lb rifle, if that. Not a huge deal. But how much more barrel life is there? Does it withstand a rapidly fired string better? And is there enough metal in the chamber end that it can be re-chambered when it is shot out? It is a pricey barrel but is it worth it in practical terms?
Buyer Beware, I pulled the trigger on a Proof barrel the end of March, 24" 6.5CM & put a APA LB on it. After trying Lapua 123 - 139, 140 RDF & CC, 140 & 147 ELD, 130 & 140 hybrids with Alpha & Lapua brass, Varget & H4350 I went with the 140 hybrid, 42.6 H4350 & Lapua brass because they seemed to have less POI shift as the barrel gets warm. 3 shoot groups all acceptable in the node - 1/2 moa but a 5 shot group lucky to be under MOA. A few weeks ago I took it to the local PRS type match and ran it a little harder, one stage had a 15 shot rapid (-2 minutes) & by the 13 - 15 shoot I saw them impacting 3+ MOA from POA @ 600 yards. Cool looking, nice balance on gun but I would rather have a rusted pipe that shot. Very $$$ target stand ?? Save for hunting when I want to pack a 15 lb AX. Called MHS more than a week ago & they were / are going to call me back, pretty crappy CS for $1450 barrel. Never again, I could have bought a complete rifle for less that would have shot better. Next step is to contact the factory but seeing their video's showing & bragging about MOA groups at best I'm probably f'd. Mnt hunting gun maybe but target / PRS I don't think so, maybe I have bad luck or just suck IDK but it leaves a very big knot in my gut.
I run a Proof stainless on my comp gun. And shoot monthly with Nate Lauerman, a Proof jersey shooter.
From PRS perspective, it's dollars and cents. When you are blowing through 3 to 5 barrels a year (or more) it doesn't make sense to run a CF barrel on a comp gun. I'm on my second barrel now, and after the Mile High shoot next month in Craig Colorado, I'll need a 3rd. And I do the bulk of my practice through a 223 trainer, saving my comp gun for matches. I certainly wouldn't drop all that coin on CF.
And the last caveat to CF for PRS, is weight is your friend. No reason to shave pounds. That's personal preference mostly, but I ran a CF barrel on my comp gun last year, and I enjoy the extra weight on this years rifle.
I do have a Proof CF barrel on my 300 Norma mag though. I hunt with that rifle and tinker at ELR with it. It's certainly ideal for that kind of usage.
Bryan Litz did a really interesting study on exactly this question in his Modern Advancements, Vol. 2. Don't have it in front of me, but if I recall correctly, the general idea was that a 4 lb. CF barrel is stiffer and better at heat management than a 4 lb. steel barrel, but that with two barrels of the same contour, the steel barrel was both stiffer and better at heat management. If I recall correctly, the steel barrels also tended to group better.
Someone feel free to correct me if I'm wrong, just going off how I remember it.
Someone feel free to correct me if I'm wrong, just going off how I remember it.
How would I bed a pressure point on an AIAX? I've been trying everything I could think of.
I happen to have Litz's volume 2 in front of me and just read that chapter. My takeaway was that there wasn't much heat dissipation difference at all. But, what really surprised me was how much POA changed on the Proof barrel in his hot barrel test of 50 rounds in 3 shot groups. They ran two Proof barrels and one was found to be out of spec so they ignored the results from that barrel. Even with the 'good' Proof barrel there was .88 POI shift while the Christensen carbon only had .35. The Proof showed only .5 over the first 35 shots and the last three groups changed the shift to .88. Even at .5 the Christensen performed better. It was second only to the Heavy Palma #1 steel barrel. Quite impressive if you ask me.
I've had two Proof carbon barrels (with another ready to chamber) and they have both shot fantastic. As well as any steel barrel I shoot. I may have to look at one of Christensen's barrels now.
I've had two Proof carbon barrels (with another ready to chamber) and they have both shot fantastic. As well as any steel barrel I shoot. I may have to look at one of Christensen's barrels now.
Funny you should ask. Literally got the email tonight confirming my dissertation being accepted and being eligible to graduate.
Unfortunately, in terms of this question, a lot changed between then and now. I ended up focusing almost entirely on barrel dynamics in steel barrels and neglecting both thermal behavior and composite construction. I did gather a limited amount of experimental data using a composite barrel and built the capability to handle those geometries into my model, but never got beyond that point.
In some ways I regret that I didn't push harder to pursue the thermal modeling harder, but at the end of the day it's the advisor calling the shots. He was more interested in the forced vibration side of things, and it turned out to be more complex than anticipated in steel alone.
I hope that I'll get to pursue it further, but now that I work in the industry I suspect I won't be able to publish my findings even if I do.
Unfortunately, in terms of this question, a lot changed between then and now. I ended up focusing almost entirely on barrel dynamics in steel barrels and neglecting both thermal behavior and composite construction. I did gather a limited amount of experimental data using a composite barrel and built the capability to handle those geometries into my model, but never got beyond that point.
In some ways I regret that I didn't push harder to pursue the thermal modeling harder, but at the end of the day it's the advisor calling the shots. He was more interested in the forced vibration side of things, and it turned out to be more complex than anticipated in steel alone.
I hope that I'll get to pursue it further, but now that I work in the industry I suspect I won't be able to publish my findings even if I do.
Might need your input on the barrel tuners thread then, since your experience aligns with the subject of barrel harmonics.
I've posted in a couple of those before, I think I've even posted a few plots from my thesis. The signal-to-noise ratio is usually pretty poor in those threads though. If anything, my main conclusion has been that it's a much more complex problem than people realize and I probably have more questions now than when I started.
This is how just about everything one specializes in goes.
Before you study a topic, you don't even have the education to ask the question. Now that you do, you have a lot of questions.
I don't think many realize how little quality data they are getting with their tuner tests.
I bet if a proper test was conducted that compared the alleged optimal tuner load of many on here that use tuners, and compared the results against an equal number of complete random tuner settings, you would see little difference in precision between the two.
Now you have fluted barrels that are wrapped. It doesn't seem that complicated to a dummy like me to test this?
Get an electric hot rod, insert into barrel for certain time, take out and monitor interior/exterior timed temperature loss?
what am I missing? you can compare any type of barrel like this?
Get an electric hot rod, insert into barrel for certain time, take out and monitor interior/exterior timed temperature loss?
what am I missing? you can compare any type of barrel like this?
