WM Intimidator 4 build question

[DHays]

Just had a couple of questions before I start building this kit.

It has a 75mm motor mount and 3/16" G10 fins. I am planning on flying it on K and L motors and maybe on a baby M. Since the fin root is roughly 1/2 deep, I didn't know if I should lay small strips of fiberglass cloth between the fin root and the motor mount tube for extra reinforcement? I will be using West System 105/205 with the fiberglass cloth. Or, I was thinking about not using the cloth and use 105/205 for the internal fillets between the fin root and motor tube and fin root and inner air frame. Then pour in urethane expanding foam. Then install the after CR. Since the fins are a little larger than what I am used to working with, I was a little worried about popping a fin on landing (frozen ground). I should be able to get a 60" Recon chute in the payload.

Also, with the size of the fins, I didn't know if I should be concerned with motor selection as far as avoiding fin flutter. Or maybe fin flutter is not a concern for the this?? I really like the kit, just wanted to error on the safe side.

Thank you!

 

[sharkbait]

Just had a couple of questions before I start building this kit.

It has a 75mm motor mount and 3/16" G10 fins. I am planning on flying it on K and L motors and maybe on a baby M. Since the fin root is roughly 1/2 deep, I didn't know if I should lay small strips of fiberglass cloth between the fin root and the motor mount tube for extra reinforcement? I will be using West System 105/205 with the fiberglass cloth. Or, I was thinking about not using the cloth and use 105/205 for the internal fillets between the fin root and motor tube and fin root and inner air frame. Then pour in urethane expanding foam. Then install the after CR. Since the fins are a little larger than what I am used to working with, I was a little worried about popping a fin on landing (frozen ground). I should be able to get a 60" Recon chute in the payload.

Also, with the size of the fins, I didn't know if I should be concerned with motor selection as far as avoiding fin flutter. Or maybe fin flutter is not a concern for the this?? I really like the kit, just wanted to error on the safe side.

Thank you!

I used West Systems and clothed the internals, Proline 4500 for the externals. No issues with M’s or landings

 

[Theory]

I built a very similar rocket with the same target impulse range.

Used "epoxy dams" to create pockets that hold the fins. Has worked great!

search for "no limits" and the build thread should appear.

 

[DHays]

I used West Systems and clothed the internals, Proline 4500 for the externals. No issues with M’s or landings

Thank you Sharkbait for the info.

 

[DHays]

I built a very similar rocket with the same target impulse range.

Used "epoxy dams" to create pockets that hold the fins. Has worked great!

search for "no limits" and the build thread should appear.

I did a quick read on your build thread this morning before I went to work. I do like that idea for the epoxy dams. I might give that a try.

Also, while reading your build thread, I saw that your booster harness twisted up, knotted real bad spinning under decent. I have had the same experience on some of my rockets, even with a swivel on the booster. Now the swivel was a non ball bearing swivel. How did the heavy duty bearing swivel work out for you? I'm starting to think that the booster section on a larger fin rocket has a greater tendency to spin more horizontally coming in under decent than a rocket with smaller fins? I don't know.

Thank you for your advice!

 

[Theory]

I did a quick read on your build thread this morning before I went to work. I do like that idea for the epoxy dams. I might give that a try.

How did the heavy duty bearing swivel work out for you?

Believe you will like the epoxy dams if you go that route. VERY strong.

As for the swivel, her highest flight to date is a tick over 6,300'. Came down just fine with no twisting. 100% agree that large fins can create issues with spinning.

 

[dmaaero]

As a avid fisherman, i can tell you the ball bearing swivals are 100 times better. The regular swivals don"t even come close.

 

[DHays]

Thank you dmaaero, I will defiantly give it a try.