sandmantoy
Well-Known Member
- Joined
- Jan 27, 2009
- Messages
- 541
- Reaction score
- 1
Does anyone know how much force it takes to shear #4 or 4-40 nylon screws. This would be the ones from Mcmaster Carr. I believe it is 35 pounds to shear the #2 or 2-56 nylon screws. Not sure on the 4-40 pins.
I am working with a 1.64 airframe 5.0" in length. Estes tubing reinforced with aluminum tape, I don't know what the mil is on it but I do know it is now stronger than the stock tubing. I come up with 51.38 psi to shear 2, 4-40 pins using .28 grams of 4F BP. I haven't ever pressurized this small of airframe tubing before. Does this sound like to much pressure for this tubing?
If the tubing was one more inch in length I think I could use less pressure to shear the pins. Didn't have the option for that or to use 2-56 nylon screws.
The airframe is reinforced at the shear pin area with .005" brass shim stock and the tubing has been hardened with cyano. I am relatively sure it will get the chute out lol. I plan on testing it before putting it on the pad but I have no more tubing to replace it with if I blow it before the launch. I am sure it is going to be over a 250 pound pop. I could lower the pressure and just pressure fit the NC but what fun would that be
I am working with a 1.64 airframe 5.0" in length. Estes tubing reinforced with aluminum tape, I don't know what the mil is on it but I do know it is now stronger than the stock tubing. I come up with 51.38 psi to shear 2, 4-40 pins using .28 grams of 4F BP. I haven't ever pressurized this small of airframe tubing before. Does this sound like to much pressure for this tubing?
If the tubing was one more inch in length I think I could use less pressure to shear the pins. Didn't have the option for that or to use 2-56 nylon screws.
The airframe is reinforced at the shear pin area with .005" brass shim stock and the tubing has been hardened with cyano. I am relatively sure it will get the chute out lol. I plan on testing it before putting it on the pad but I have no more tubing to replace it with if I blow it before the launch. I am sure it is going to be over a 250 pound pop. I could lower the pressure and just pressure fit the NC but what fun would that be