Introduction

[Yoda]

Hi there,

I just joined today because I took my son over the Christmas holiday to see his cousins and amongst the many things he did with them is launching rockets. Today I bought an estes leviathan rocket which I will build for him and with him. I was reviewing some instructions here about the build and some mentioned if the person was going to use internal fillers during the build. I never heard that term before and I have no idea what is involved. Is there a post thT can help me understand this better so the build can be durable. Thanks in advance

 

[smstachwick]

Hi there,

I just joined today because I took my son over the Christmas holiday to see his cousins and amongst the many things he did with them is launching rockets. Today I bought an estes leviathan rocket which I will build for him and with him. I was reviewing some instructions here about the build and some mentioned if the person was going to use internal fillers during the build. I never heard that term before and I have no idea what is involved. Is there a post thT can help me understand this better so the build can be durable. Thanks in advance

I can only assume you or the other person meant “fillet.”

The idea is that you want to put extra glue at the joint between the fin and body tube, on the inside as well as the outside, then smooth it as illustrated. Easy enough to do with your finger.



This gives the fin extra surface area to bond to, reducing breakage when the rocket touches down. The sizing and neatness aren’t super critical unless you’re doing a high-power mega-project that’s expected to encounter heavy aerodynamic loading.

They’re not even strictly necessary with Estes kits, but it makes them a bit tougher if you’re already making modifications that make them heavier.

 

[MarsLander]

Internal fillets are between the through the wall fins and the motor mount tube, and between the through the wall fins and the inside of the airframe.

 

[Hobie1dog]

 

[Yoda]

I can only assume you or the other person meant “fillet.”

The idea is that you want to put extra glue at the joint between the fin and body tube, on the inside as well as the outside, then smooth it as illustrated. Easy enough to do with your finger.

View attachment 624446

This gives the fin extra surface area to bond to, reducing breakage when the rocket touches down. The sizing and neatness aren’t super critical unless you’re doing a high-power mega-project that’s expected to encounter heavy aerodynamic loading.

They’re not even strictly necessary with Estes kits, but it makes them a bit tougher if you’re already making modifications that make them heavier.

I think you are spot on but I have no idea how one can put internal fillets on the inside of the estes pro ii series as there is the centering ring covering access

 

[MarsLander]

I think you are spot on but I have no idea how one can put internal fillets on the inside of the estes pro ii series as there is the centering ring covering access

The technique is to drill a couple holes in the rear centering ring. Weave some kevlar through the holes. When you glue in the motor mount, you only glue the forward ring. Put the rear in place to hold the MMT in the right position. After the forward ring is dry, pull the rear ring using the kevlar. Do the internal fillets. Then glue the rear centering ring in place after removing kevlar. I'll try to find an explanation and I'll post it.

 

[neil_w]

Welcome!

Amazing that no one ever took that username before.

 

[MarsLander]

Here is a TVM video explaining the process...starting at 2:30:

 

[Yoda]

The technique is to drill a couple holes in the rear centering ring. Weave some kevlar through the holes. When you glue in the motor mount, you only glue the forward ring. Put the rear in place to hold the MMT in the right position. After the forward ring is dry, pull the rear ring using the kevlar. Do the internal fillets. Then glue the rear centering ring in place after removing kevlar. I'll try to find an explanation and I'll post it.

If the idea is to add strength to the internal part of the wings and stability, couldn't I drill small holes in the bottom centering ring and spray in some foam. Then do some fillet from outside.

 

[Art Upton]

Foam Crushes, so it adds nothing. It was a gimmick from a past kit vendor.

 

[MarsLander]

If the idea is to add strength to the internal part of the wings and stability, couldn't I drill small holes in the bottom centering ring and spray in some foam. Then do some fillet from outside.

The point of the internal fillets is multi-fold.

The thrust is all in the motor mount...moving forward. The centering rings can typically handle transferring the thrust to the airframe...the internal fillets use the through the wall tabs of the fins to increase the connection between the motor mount and the airframe.

The fillets also tie the fins to both the airframe and to the MMT...strengthening the fins and fin connection to the airframe and MMT.

Purpose and method aside, if you get enough glue on the MMT with the TTW fins, on a PSII rocket, it should be fine without the INTERNAL fillets. You should still use external fillets.

 

[teepot]

Welcome to the Forum.

 

[OzHybrid]

The thing with glue is it's heavy..... Only use the amount you need. More is NOT better especially at the motor end as that adds weight where you don't need any more than necessary.
Satay skewers with a flat cut onto them like a screwdriver will hold small amounts of most types of glue to enable you to get glue in some deep impossible places....
Good luck in your journey.

 

[Greg Furtman]

Be careful using yellow glues like Titebond when gluing rings and couplers. Unless you are very quick you will find that yellow glue becomes very "sticky" almost right away. There's been times when I've tried installing couplers, internal rings, etc that I failed to get them in all the way. I now use 15-minute or 30-minute epoxy as it gives me more time to get things into position properly. Makes for good fillets too if you thicken it a bit with sanding dust.

 

[John Kemker]

Be careful using yellow glues like Titebond when gluing rings and couplers. Unless you are very quick you will find that yellow glue becomes very "sticky" almost right away. There's been times when I've tried installing couplers, internal rings, etc that I failed to get them in all the way. I now use 15-minute or 30-minute epoxy as it gives me more time to get things into position properly. Makes for good fillets too if you thicken it a bit with sanding dust.

Careful! Don't turn this into a glue thread! LOL

 

[Greg Furtman]

Careful! Don't turn this into a glue thread! LOL

Just a matter of experience.

 

[Yoda]

Welcome!

Amazing that no one ever took that username before.

My son was born on May 4th, so it was fitting

 

[neil_w]

My son was born on May 4th, so it was fitting

Did you name him Luke?

 

[Yoda]

Here is a TVM video explaining the process...starting at 2:30:

Thanks for the video. I can see how that would make super solid.