4" Madcow Black Friday AGM 33 Pike "Overbuild" Thread

Started building today, it may be a slow thread but here goes....
I started measuring and weighing each part to work up my OR file (still in progress)

But first an overview....

The kit seems well manufactured and packed perfectly! No damages from shipping!
Here's the kit laid out....


The odd thing is, it has 2 sets of fins but only comes with 2 centering rings, my thought is that each fin set should be "captured" by 2 CRs so it should have 4, I know it's designed by people who know WAY more than I but...
I ordered 2 more CRs....only to discover that the lowest CR would be a little over 2" ABOVE the trailing edge of the bottom of the lower body tube If I butt it up to the aft fin set.
I've read that the bottom gets dinged up sometimes on hard landing so I'm still deciding on placement of the bottom CR. Plus I'm still deciding on which motor retainer to buy since it doesn't come with one.

Back to the overview...Let's start with the "bad"...not necessarily in order...

1. Parts Fit:
The centering rings fit pretty loose on the MM tube and inside the body tubes.
Not a big deal inside the BTs, but more so on the motor tube, it is glassine coated, which means that you have to sand it for glue adhesion, which means that it will get even looser inside the centering rings.
Which means that things can get canted upon assembly, not a huge issue but one that could bite new builders going to something bigger that Estes kits/fits.

2. Glassine Coated Motor Tubes:
I really don't understand why ANY HPR rocket manufacturer would use glassine coating. It inhibits adhesion with all adhesives (by what I've researched here on TRF), and to sand or peel it for adhesion, you thin and weaken the original tube structure, which seems to be counter productive to both rocket integrity and build times.
JMHO

3. This kit should come with 4 centering rings...MHO
If built as per instructions there are NO centering rings abutting any fin tabs.
Again, the manufacturer knows way more than I, and many have flown this kit "as per",
but I just have to build it with "thrust transfer integrity" (did I just make that up??? LOL)....which will be seen as this thread progresses.


Now to the Good!

1. Body Tubes:
Despite the glassine, they are well made, no complaints about the spiral seam thickness, the glassine on a body tube shouldn't affect primer adhesion for me since I like to start with duplicolor etching primer on all rockets.
I'll have to sand a little deeper where my fin fillets will go but thats part of the "build monster"

2. Coupler Tube:
This thing is BEEFY!!! I know that it's meant to be a "shoulder" with a bulkhead/chute-hook more than being just a "coupler" but this thing is nice. And you could absolutely use it to make an ebay.
Here on the left is the Madcow compared to the Loc 4" coupler on the right...both 8" long.
Madcow: .093" wall thickness, 4.3 oz
Loc: .038" wall thickness, 1.7 oz


3. Nose Cone:
Very nice seams/molding sprue!
I've seen rougher seams on 2" Estes cones and this is a 4"!
Should be a breeze for primer prep!!!
PLUS it's POINTY on one end!!! LOL

4. Kit In General:
I love this kit! It's a different facet from the usual "pop the nose" deploy rockets in the LPR/MPR range.
You can go basic, you can go duel deploy and make your own sled and use the coupler that comes with it for your ebay (which I'm considering...maybe.....still above MY goals as yet).
It has everything but the chute and the motor retainer...you can take it where you want, and I hear it's a pretty good flyer.....not so much a lander LOL!
But I have ideas!!!

So, ON TO THE BUILD!!!!

The SLOW part!!!

First I cut a ring section from one of the extra Loc tube couplers that I picked up when I bought the Goblin to go above the forward centering ring for "thrust reinforcement"....(my overbuilding)


Measured and weighed for my OR file, I set it up
using a "witness line" on the coupler tube before I added a bead of BSI 30 min epoxy.



Then pushed it into place....

Then removed the coupler tube AND the centering ring and let the epoxy set up for about 20 minutes.
Then I added another bead of 30 minute and installed the forward centering ring up against the reinforcement ring. Two separate parts, two separate glue ups.

Then, I noticed I made a BIG BOO_BOO!!!!
I've been doing 4 fin rockets and I used the "top" 2 fin slots to align the chute hook to the bottom of the BT center to be opposite of the side that I put the lugs/buttons on.....
Well, this is a 3 fin rocket so I ended up with this..

Chute hook PERFECTLY aligned with a FIN SLOT!!!!
Had to do a little trimming on a fin!!!!

GEEEEEZE!!!!!!

Anyhow, she fits good!!!

So if you noticed, I installed the most forward CR without the motor tube.
The plan is to install that after I bevel the edges of the fins (waiting for the Typhoon bit I ordered) and since the motor tube is kinda loose, I'll glue that up using a "dry placed" CR at the rear of the body tube shortly before gluing the forward fins on. Then I can "overbuild" by placing internal fillets before installing the forward fin-aft centering ring in place.

More to come....slowly...LOL

Thanks All!!!!

Had some minimal activity on this build.
Still waiting on the Typhoon bit I ordered to bevel the fins so I can start assembling the fin can. Looks like it may be here today...hopefully!

I got the first coat of primer on the nose cone, weather hasn't been "spray friendly" lately. Today and tomorrow are looking better.

Been playing with the glassined motor tube, "wet" peeled the outer layer off and found what seems to be an even more impervious layer coating the cardboard, CA sticks to it but not epoxy. So...

I scuffed the areas where the CRs fit with some 36 grit sandpaper to make some deep scratches towards the cardboard so maybe It'll have some absorption for the epoxy.

I've ordered the motor retainers (Aero Pack), 2 bases- one for this and one for the Aerobee-Hi and 1 cap, looks like they'll be here Monday.
I've been tweaking up my OR file a little, still need to purchase a few items like chutes and such to get final weights for OR.

But of course, accurate OR files dynamically change as the build progresses, considering glue and paint and "extras" that each of us add to our own.
The stated weight for this one is 60 oz, I weighed up what came in the package,...60 ozs, no chute, no retainer, so OR will be updated.

I made another OR file for the fin can structure to demonstrate my "overbuilding expertise"
FWIW, if I had a place closer that I could fly, I would fly nekkid and burn "powder" as often as possible, but I don't, so,
for me right now, building is the fun part and I like to build "tanks"!!!
I'm 187% sure that there will not be a structural failure from normal motor thrust.

Heres that OR file, FWIW,

Nose cone and MMT so far.



I'm using Dupli-Color "Self-Etching" Primer to get some bite on the nose cone plastic.
I'll build up with that and sand/repeat until I don't see any plastic coming up after sanding, then I'll primer up with a "filler primer" and sand/repeat until I get smooth surface ready for paint.
I do have a lot of room to fill to get the nose cone O.D. to match the body tube O.D. so it should turn out pretty smooth.
Just got a couple more coats on it. Painting weather is looking GOOD today...
Wish I was painting instead of primering...but I'll take it!!!

My Typhoon bit came in today along with the retainers.
Hope I can finally get to building this week.

Well...
I set up my bit in the router (poorly) and got pretty much mediocre results beveling the fins...MY FAULT!!!
I was in too much of a hurry and haven't really used the router for anything precise in almost three years.
Not a total loss, found some other fin beveling techniques here on TRF so...gotta do a bit more work to clean it up...but still,
fins are looking good!!!
No pics of it so far...
Nothing to see here, move along.....

There is definitely a Pike in my future... Great lookin kit.

I'd be interested in seeing the set-up you use to router fin bevels. I don't have any real woodworking power tools in my shop, so fin bevels are a hand wrought affair around here!

I suppose an angle grinder would make short work of a (or the entire) fin...

Mugs914 said:

There is definitely a Pike in my future... Great lookin kit.

I'd be interested in seeing the set-up you use to router fin bevels. I don't have any real woodworking power tools in my shop, so fin bevels are a hand wrought affair around here!

I suppose an angle grinder would make short work of a (or the entire) fin...

Click to expand...

I also did my fin beveling "by hand" with a belt sander mounted upside down on my work bench and slowly worked the fins into shape.
Kinda rough and only as accurate my failing eyesite!!!

This bit has the potential to be accurate, I was just in too much haste to set it up for more accuracy.

Here's my rig...and it's set up pretty primitive for something that needs to be a little more precise.
Just a router with the bit shown above in post #4, problem was that the opening in the fence around the bit was way too big and the table insert plate sits about .020" below the table surface. I fixed the plate surface with some paneling clamped to the table, but that was after I had already botched 3 out of 6 fins!
View attachment 403314

And OK, here's some pics of the fins.
I intentionally left some material on the fin edge (thank goodness) knowing that the bit does cut a little rough and would need some final sanding, plus I knew I had a learning curve with this bit, never used it before.


From 10 feet away they don't look too bad, unfortunately aerodynamics doesn't stand that far away! LOL
The bit is 15°, I'll make me up a sanding jig at around 10° and creep up to the fin CLine, hoping I didn't already pass it and smooth out my router set-up learning curve.
Now for my next learning curve....making a sanding jig to bevel fins!!!!
There are many resources here for just such an endeavor!!!

Looking good, I will be watching this thread for sure! Split fin designs are definitely a fav.

Those bevels are great.

This is one of those "do i risk borking it further by trying to fix it" times

Nytrunner said:

This is one of those "do i risk borking it further by trying to fix it" times

Click to expand...

LOLz - if it ain’t broke, fix it till it is!!!

but seriously, touch em up a little and fly

Hooked On Rockets said:

I also did my fin beveling "by hand" with a belt sander mounted upside down on my work bench and slowly worked the fins into shape.
Kinda rough and only as accurate my failing eyesite!!!

This bit has the potential to be accurate, I was just in too much haste to set it up for more accuracy.

Here's my rig...and it's set up pretty primitive for something that needs to be a little more precise.
Just a router with the bit shown above in post #4, problem was that the opening in the fence around the bit was way too big and the table insert plate sits about .020" below the table surface. I fixed the plate surface with some paneling clamped to the table, but that was after I had already botched 3 out of 6 fins!
View attachment 403314 View attachment 403313

And OK, here's some pics of the fins.
I intentionally left some material on the fin edge (thank goodness) knowing that the bit does cut a little rough and would need some final sanding, plus I knew I had a learning curve with this bit, never used it before.
View attachment 403315 View attachment 403316 View attachment 403317 View attachment 403318 View attachment 403319

From 10 feet away they don't look too bad, unfortunately aerodynamics doesn't stand that far away! LOL
The bit is 15°, I'll make me up a sanding jig at around 10° and creep up to the fin CLine, hoping I didn't already pass it and smooth out my router set-up learning curve.
Now for my next learning curve....making a sanding jig to bevel fins!!!!
There are many resources here for just such an endeavor!!!

Click to expand...

Ohhh how i wish there was an easier way to make those bevels...

Whoever figures it out will be a ga-zillionaire...

thanks for posting tho'!

fm

Nytrunner said:

Those bevels are great.

This is one of those "do i risk borking it further by trying to fix it" times

Click to expand...

Theory said:

LOLz - if it ain’t broke, fix it till it is!!!

but seriously, touch em up a little and fly

Click to expand...

LOL, Thanks!!
But I just can't accept installing something that I know I can do better....
Especially with the biggest rocket I've had the pleasure to work with so far....just wish I had more free time...
I have a few ideas to get them where I want them, but I either have the tools and not the materials, or
I have the materials and not the tools...GO FIGURE!!!!

Forever_Metal said:

Ohhh how i wish there was an easier way to make those bevels...

Whoever figures it out will be a ga-zillionaire...

thanks for posting tho'!

fm

Click to expand...

That would be nice!
But it is still in progress.

Think we all have the time vs materials vs tooling problem. Regardless, this looks like a good starting place for bevels. Thanks for putting up pics and such...

I got the fiberglass one but have not started building it
https://www.madcowrocketry.com/4-fiberglass-pike-xl/

Finally some progress...
I made me up a better router fence


and crept up with some small passes over the router bit and
the fins are looking sharp!! Literally!
They look tons better and any remaining imperfections will be taken care of during the priming stage.



Of course I'll saturate the edges with thin CA after they are installed before priming.

With an 18" long motor tube, I dry fitted the motor retainer and a centering ring, then wrapped some masking
tape to hold it in place while I epoxy it (and the front fins later) in place.


Then, I could mark the motor tube where the epoxy goes and push it past the front of the body tube and apply the epoxy.

Then slide it back into position and not have excess epoxy get where the fins will go. (epoxy not shown)

And finally got a fin glued on...

One down...FIVE to go!!

Forever_Metal said:

Think we all have the time vs materials vs tooling problem. Regardless, this looks like a good starting place for bevels. Thanks for putting up pics and such...

Click to expand...

Thank You!!!

jbr said:

I got the fiberglass one but have not started building it
https://www.madcowrocketry.com/4-fiberglass-pike-xl/

Click to expand...

Thats NICE!!!
...dreaming of fiberglass...

2. Glassine Coated Motor Tubes:
I really don't understand why ANY HPR rocket manufacturer would use glassine coating. It inhibits adhesion with all adhesives (by what I've researched here on TRF), and to sand or peel it for adhesion, you thin and weaken the original tube structure, which seems to be counter productive to both rocket integrity and build times.
JMHO

3. This kit should come with 4 centering rings...MHO
If built as per instructions there are NO centering rings abutting any fin tabs.
Again, the manufacturer knows way more than I, and many have flown this kit "as per",
but I just have to build it with "thrust transfer integrity" (did I just make that up??? LOL)....which will be seen as this thread progresses.


I Totally agree - I love their kits , but I always and up making or ordering more C/R's to feel better about the build -
Im an "over builder" club member myself - better strong than broke- plus I can always add more motor
Following with interest , I scratch build on out of 2.6 PS II parts and flew it on too light of a motor on a windy day and payed the price - I may may re-build it one day , but anything under 3 inches is kinda a pita - Im spoiled.

glassine is easy to either peel or simply wipe with a damp cloth, its only paper thats been "calendared".

Looking good! And remember, perfection is the enemy of good enough.

I got the third fin on tonight (2nd one last night),


I hope to get the 2nd and 3rd CRings on tomorrow along with the internal fillets and
then get the 3 aft fins on over the weekend....

Andy Greene said:

I Totally agree - I love their kits , but I always and up making or ordering more C/R's to feel better about the build -
Im an "over builder" club member myself - better strong than broke- plus I can always add more motor
Following with interest , I scratch build on out of 2.6 PS II parts and flew it on too light of a motor on a windy day and payed the price - I may may re-build it one day , but anything under 3 inches is kinda a pita - Im spoiled.

Click to expand...

That looked like a nice scratch build!
Bummer to see it crashed!!!

I do like this kit design....I would have done some things differently....but then again....it wouldn't be at such an absolutely reasonable price, especially at the Black Friday price!!!

This is my 2nd 4"er and it is so nice to be able to reach into the Btube to connect/disconnect chute cords and such...

Thanks for the follow BTW!!!

rharshberger said:

glassine is easy to either peel or simply wipe with a damp cloth, its only paper thats been "calendared".

Click to expand...

Yes, I discovered that on this build (post #2) playing with finding an easier way to "scuff sand" it....
But again as in post #1, the CRs fit loose on the motor tube as they came, you peel the outer glassine layer and the fit is looser,
Then as mentioned, again in post #2, the coating thats left after the glassine is removed is MORE impervious to epoxy saturation/adhesion (I did use less words there)...
So then to sand THAT layer off all the way to the cardboard the fit would be even looser.....
I just dont get why anyone puts glassine on any rocket part....It's basically worthless.

JMHO

Flyfalcons said:

Looking good! And remember, perfection is the enemy of good enough.

Click to expand...

LOL
Thank You Thank You!!!!

That thing is really looking good Hooked! I know it took a little doin' but you really nailed the bevels. Those fins look great!

Keep up the good work...

Amazing Finwork!

I got the internal fillets on the forward fins over the weekend, got a picture of the "before" but didn't get an "after" of the innerds...
Got the aft CRing installed on the forward fins....not much else, the plan I had got held up by a drop of epoxy that I didn't see on the motor tube somewhere while doing the fillets...DOHHH


The highlighted piece was going to be a "thrust transfer" tube to integrate the fore and aft fins/CRings etc.
Do I need it??? NO, but I would have felt better.
But that was the last piece of that size that I had (it's a coupler tube from the Aerotech Mustang)..
Anyway...
More in the future.....
SS

Mugs914 said:

That thing is really looking good Hooked! I know it took a little doin' but you really nailed the bevels. Those fins look great!

Keep up the good work...

Click to expand...

Thank you Sir!!!
I was sweating it until I took the time for a new fence and set-up.
Thank goodness I didn't go too far on the first set-up (that much)!
Wasn't much room for error!
TIME...so valuable and so elusive some times!
SS

Lukun7 said:

Amazing Finwork!

Click to expand...

Thank you Sir!!!
I do try to do good work, both structurally (over-do) and cosmetically (the best I can).
Many say that their rockets have to "earn its paint"...
I say my rockets have to "earn its scars"
SS

A little more work on it today,

Got these three pieces installed today..

L to R...


Thrust reinforcement ring that goes up against the forward fin AFT CRing on the motor tube...
installed...

Then the outer reinforcement ring that goes above the 3rd CRing.
Then the 3rd CRing (which is the forward CR of the aft fins).
All installed,
I'll let the epoxy (30 minute BSI) kick of for a couple hours and I'll be ready to start installing the aft fins!!!

SS