Cert 1 Rocket Nose cone/shock cord link

[Jacktango22]

Scratch building a level one with a 3 inch tube, and nose cone in attached photo. The design of the nose cone attachments are new to me. Any help much appreciated.

I have a 1500 lb test circular Kevlar cord that I planned to connect directly from motor mount screw eye bolt to the nose cone but keeping options open.

thanks

 

[jmasterj]

If your nose cone doesn't have any extra weight in it, you can use the pair of holes. Alternatively, the light/strong/simple method is to cut two small holes in the shoulder base and thread some Kevlar through them, either a standalone loop or the rocket harness. A screw eye will likely be weaker than that connection unless you make a hole to give it a nut on the back side (and at that point you can use the kevlar loop method anyway).

 

[jbsommerfeldt]

That looks like one of the LOC or PML really thick nose cones. I like to use a toggle bolt with a threaded eye in the center hole. You will need to trim the already drilled hole a bit. You might even need to drill it bigger. Or, if you dont want the weight, run a loop of left over cord through the two tabs on the cone. I do NOT recommend running the cord directly from MMT to NC. Leaving the nose cone an eye or loop gives you options for repair or what ever you want to attach to it. Iv also had to move a NC from one rocket to another. Being able to just disconnect it is the easiest.

 

[jmasterj]

Not LOC, that's PML or Pinnacle. I prefer not directly connecting as well, but no it does save you some weight.

 

[waltr]

Drilling two holes and put a piece of heavy Kevlar through works great.
Picture is the recovery setup on my LOC 4" Goblin which got me L1 cert.

 

[K'Tesh]

Whatever you decide, do not have the parachute attached direct to the plastic of the NC. Have it secured to an eyebolt or the shock cord. You don't want to have a failure because the shock of the nosecone coming under tension from both the rocket and the chute breaking the connection.

 

[jmasterj]

Drilling two holes and put a piece of heavy Kevlar through works great.
Picture is the recovery setup on my LOC 4" Goblin which got me L1 cert.

What are the two nomex blankets for?

 

[Ronz Rocketz]

Dave does a good job talking about the connectors.

 

[waltr]

What are the two nomex blankets for?

The lower one is to protect the Nylon cord from ejection charge.
Top one wraps around the chute to protect it, also help to deploy chute smoothly by pully lines out first.
The braided cord is to absorb the engery of ejection and prevents the 'shock' when the cord fully extends which is what breaks things.

 

[boatgeek]

I have seen a lot of failures on cert flights from shock cords pulling out of the small tabs on LOC nose cones. Including my own first cert flight.

I like to drill a medium-size (like 1"-1.5" diameter) hole in the side of the shoulder. Then I put an eye bolt (preferably forged or welded closed, not just bent) through the center hole and use the shoulder hole to put a washer and nut on the back side with long pliers. Use Loctite or a nylock nut to keep the eye bolt from backing out of the nut. It takes a little bit of juggling and swearing, but it makes a rock-solid connection. It does add some weight, but it's in the right place at least.

 

[Jacktango22]

I weas actually thinking about ways to put an electronic gizmo or two inside the shoulder of the nose cone in lieu of a payload section.

 

[David_Stack]

I weas actually thinking about ways to put an electronic gizmo or two inside the shoulder of the nose cone in lieu of a payload section.

https://macperformancerocketry.com/products/pinnacle-nosecone-bay-kits

 

[jmasterj]

I weas actually thinking about ways to put an electronic gizmo or two inside the shoulder of the nose cone in lieu of a payload section.

Chop the closed end of the cone off and put a tube in it with a couple centering rings. Lots of people have don't variations of this.

 

[conneryc]

I personally cut the end off of the shoulder and epoxy in a bulkhead with a eye-bolt or U-bolt where the transition between the shoulder and the cone is. This makes it impossible for the bulkhead to come out as it's the same diameter of the ID of the cone, and sits on the transition to the shoulder.

 

[rcktnut]

Looks like a PML nose cone. I use the 2 holes on my 3" Bullpup. It has 4oz. of weight in the nose cone. It hasn't failed in 15 or so years!!