Number of Rivets?

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hussier1

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I've built a couple rockets with others, but never the rivets. Now that I'm building a rocket on my own, I realize I don't know how to choose a number of rivets. It seems to me that 3 or 4 rivets is a common number, but I don't know if the right number varies between rockets. Thinking logically, more rivets prevent the body tube from slipping on the transition, while increasing drag. Does the right number of rivets depend on the individual characteristics of a rocket, or is 3 or 4 a good rule of thumb for all rockets?

The rocket is a 66 and 56 mm tube with a F-class motor w/o shear pins.
 
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Really depends on the size of the rocket and the strength of the rivet. For really big rockets, metal screws would be a better choice. Also, if you are using shear pins I'd typically go with 1 more rivet then the number of shear pins.
 
Myself I never use rivets, just my choice. I use steel screws on everything even my BT50 size DD rockets. I will use the same # as there are fins. I also line them up on the fin line, I think it just makes everything look neater. If you are using the rivets to ensure no separation, then more is better. But it does depend on weight and drag, your recovery setup. ie, how much BP, length of shock cord and weight of NC. the more weight, the more rivets needed. A very short shock cord will snap the payload section at apogee and you will need more rivets. Also if drag is your worry, then use flat head screws in counter sunk holes. Apogee Components sells a screw washer insert kit. I have never used them but they look good. I do not remember the name of them. Maybe someone will chime in with it.
 
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Myself I never use rivets, just my choice. I use steel screws on everything even my BT50 size DD rockets. I will use the same # as there are fins. I also line them up on the fin line, I think it just makes everything look neater. If you are using the rivets to ensure no separation, then more is better. But it does depend on weight and drag, your recovery setup. ie, how much BP, length of shock cord and weight of NC. the more weight, the more rivets needed. A very short shock cord will snap the payload section at apogee and you will need more rivets. Also if drag is your worry, then use flat head screws in counter sunk holes. Apogee Components sells a screw washer insert kit. I have never used them but they look good. I do not remember the name of them. Maybe someone will chime in with it.

I also use a number of removable plastic rivets based on the number of fins, and put them inline with the fins. If I need more rivets for some other reason then I use as many as needed.
 
I stopped using plastic rivets a while ago. I use #8 screws to hold the av bay, It's faster and easier to remove than plastic. If it was something I wasn't going to take apart to fly then I might use rivets. I normally use pan head screws. On an MD I use wood screws countersunk. I normally use 4 screws for an av bay.
 
I've been gluing everything MPR DD together. Not getting the ''removable payload from coupler'' bit yet.

The HPR's I'm building use three 4-40 screws and blind nuts (epoxy covered on inside), only because ''that's how everyone is doing it''. I pop the lower bulkhead off the Av bay, and tug out the sled by the main cord. Way quicker than dealing with those screws.
 
My friends and I are fans of military vehicles. We collect by hand various mini-models of military vehicles. It's like a hobby and making a collection. This time we assembled models of military missiles much more significant than previous models. At first, we fastened the parts with inappropriate bolts, and the pieces were wobbly or fell off altogether. I looked on scrooz.com.au to see what securing systems they advised and how many. We settled on the choice of rivets. Once we got them, we were pleasantly surprised by how they harmonized with the rocket parts and fastened them very securely.
 
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