Madcow 4 inch patriot build thread

[Adam3836]

Just started to build the madcow 4 inch diameter patriot rocket was going to build this over a year ago but switched to a different rocket…. so now it’s the patriots turn
I will post the progress as I go

 

[Adam3836]

Sanded the shine off the 38mm motor tube
Put on the aft and forward rings on the motor tube along with the forward eye bolt
I used rocket poxy for all this
The black/grey color is just the mixing dye that you add to make sure you properly mixed the epoxy.
The rings fit on very loosely to the motor tube so I tacked them in with a touch of CA so it wouldnt move and then I hit it with epoxy

 

[Adam3836]

Shock cord knotted onto the forward eyebolt
Used some tape just to hold down the excess shock cord slack after the knot plus added some more down the line to assist in alittle extra shock cord protection from the motor ejection

 

[Adam3836]

Rail buttons installed and epoxied on the inside

 

[Adam3836]

Motor mount tube installed into main body tube. Aft end epoxy drying now. Aeropack retainer installed with epoxy as well.
Once this is dry I will flip the main BT over and add more epoxy to the forward ring with a long dowel

 

[Adam3836]

Next part done
Coupler epoxied in

 

[Adam3836]

Test fit all together
Still letting the epoxy cure more then Will tackle
The fins

 

[mikekebert]

Good progress for a day's work!

 

[Adam3836]

Had alittle time so I went for it lol
Should have some more time this week ?

 

[Adam3836]

epoxied fins in and fillets done


Fins

 

[Adam3836]

 

[Adam3836]

 

[REK]

Patriot is just my favorite, great work on the build.

 

[UhClem]

The rail button positions are pretty awful. Once the top button leaves the rail the aft one is worse than useless. So move it one up. (I use CG and CP as rough guides for button locations.)

Or if you are terrified of a short rail and low thrust motor, move the forward one back. Four inches or so in front of the aft button. But that location has its own problems.

 

[Adam3836]

Interesting I haven’t heard anything about the rail buttons not being placed in a good spot I will look into it thanks
QUOTE="UhClem, post: 2184609, member: 787"]
The rail button positions are pretty awful. Once the top button leaves the rail the aft one is worse than useless. So move it one up. (I use CG and CP as rough guides for button locations.)

Or if you are terrified of a short rail and low thrust motor, move the forward one back. Four inches or so in front of the aft button. But that location has its own problems.
[/QUOTE]

 

[crossfire]

Old school recommendation place top button one caliber below CG.

 

[Adam3836]

Mine are epoxied in as they lay now but ?

 

[Adam3836]

Nose cone weight added tonight used wooden dowels and bb’s
I did 3 dowels probably could of done just 2 but wanted to make sure there was plenty for the epoxy and bb’s to grab onto

 

[Adam3836]

Nose cone dowels cut sanded and nose cone glued down to the BT

 

[dr wogz]

how much weight did you add?

(I have a build thread of the same rocket. I built this & a DX 3 in parallel, since they are soooo similar!)

 

[Adam3836]

Based on the motor I was looking to use I added just about 14.7 ounces
That got the rocket back to the CG of 28inches from the nose cone tip down

 

[T-Rex]

Wowzers.... That is a lot of weight, may I ask what motor you are planing to fly?
I only added about half that, but then again, I am restricted to an I200 due to our waiver.

 

[Adam3836]

I read a lot of threads about the weight and for a 38mm 2 grain motor 14 ounces is spot on to get the CG accurate

 

[Adam3836]

I simulated the motor weight on the aft end and balanced the nose till it was level and the cg back at 28 inches from nose cone tip

 

[Adam3836]

Chipping away once a week on the patriot
Today I shaped the fins with a dremel

 

[jqavins]

Nose cone weight added tonight used wooden dowels and bb’s

Dowels because no glue will adhere to the material the nose cone is made of. Well established technique. Check.

Nose cone dowels cut sanded and nose cone glued down to the BT

Hang on a minute! Glued down with what? Either you need rivets because glue won't adhere to the nose cone, or you didn't need the dowels. Which is it?

 

[Adam3836]

The nose cone i epoxied down to the upper body tube as the directions mentioned
i scuffed up the nose cone and that’s it
It feels pretty secure but I have been researching the best way to make sure the nose stays on secure to the BT
I fully understand that epoxy doesn’t like nose cone material with the bebe’s so yes dowels we’re used
Research continues on if and what I need to make sure the NC stays put . Feels tight but under launch pressure could be a different story

Any suggestions?

 

[Adam3836]

Also I get conflicting feedback if using epoxy to connect the nose cone permanently to the upper body tube will work will that be sufficient enough
Epoxy likes wood and cardboard so shouldn’t that hold

I get it epoxy doesn’t like being used on the inside of the NC trying to stick to only plastic that’s why we use wooden dowels to help hold the epoxy in place

 

[jqavins]

Any suggestions?

Plastic rivets.

Unless the epoxy adheres well to the outside of the shoulder, in which case one would think it would adhere every bit as well to the inside of the tip.

Yes, epoxy likes wood and cardboard. It also likes metals (like BBs). It even like some plastics just fine, but it doesn't like others. At least some plastic nose cones (I have it from an Apogee video that most or all large ones) are made of polypropylene (though the small ones are often polystyrene). Epoxy definitely doesn't like polypropylene. Since the epoxy has to like both of the materials it's supposed to hold together then the fact that it likes the cardboard tube isn't sufficient if it doesn't like the nose cone.

So, you're following the directions on both ends, and I certainly can't and wouldn't fault you for that. But something doesn't smell right. To be on the safe side, I'd install rivets.

 

[Adam3836]

I appreciate the information

I agree with you !! It wasn’t sitting well with me just epoxying the NC to the BT knowing how epoxy can be fussy with plastics.

Plastic rivets seem like a easy way to make sure it’s fully secure and not coming off
I figure if I have it epoxied and I now put 4 evenly spaced plastic rivets I should be ok