Something to consider when choosing a material. Yield v.s. tensile strength. The further apart these to are from each other the more likely you are to have a soft failure v.s. an explosive failure. Soft failures result in the material expanding beyond what the seals can cover and all the air passes to atmosphere. Spooky, YES. Hazardous, YES. Life threatening, Typically, Much less likely.Bill
I'm in the process of making my own PCP, which is far from being finished, but I have every design detail worked out. When I was younger I used to play with model rockets and even make them, I used a simple XLS sheet put together by a rocket specialist named Richard Nakka used to calculate the maximum pressure that a rocket casing can withstand before bursting and you get to put in the design safty factor, tube OD and ID material shear strength and elastic limits. I find it to be very accurate and gives numbers that are very close to other calculators, the main reason I like it is because it is super easy to use. Here is a link for the sheet:http://www.nakka-rocketry.net/soft/casing.xlsI hope you find this useful.
Here is a calculator that you can use.http://www.engineersedge.com/calculators/shell_internal_pres_pop.htmSet the value for joint efficiency to "one" because you don't have any welded joints. To get your 3 to 1 safety factor you can either use 3 x the working pressure, or set the allowable stress to 1/3 of the yield strength of the metal. 6061T6 is normally speced at about 40,000 psi yield, and 45,000 tensile.Also consider 2024T3 (50,000 & 70,000) and 7075T6 (60,000 & 67,000). They are more expensive but might be worth it depending on the application. Lloyd-ss
Quote from: lloyd-ss on January 20, 2013, 12:44:45 AMHere is a calculator that you can use.http://www.engineersedge.com/calculators/shell_internal_pres_pop.htmSet the value for joint efficiency to "one" because you don't have any welded joints. To get your 3 to 1 safety factor you can either use 3 x the working pressure, or set the allowable stress to 1/3 of the yield strength of the metal. 6061T6 is normally speced at about 40,000 psi yield, and 45,000 tensile.Also consider 2024T3 (50,000 & 70,000) and 7075T6 (60,000 & 67,000). They are more expensive but might be worth it depending on the application. Lloyd-ssI just bought 1.25 2024 tube with .095 wall ,is this enough for 2500 psi?.I'm building a light weight mrod rifle. Thanks