Author Topic: Madcow 2.6" 38mm Screech  (Read 3777 times)

Offline dbmccann

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Madcow 2.6" 38mm Screech
« on: November 22, 2015, 07:15:29 PM »
This is from last year, but copying it over to add some content. Plus here it won't have all the fluff build threads seem to accumulate.
Wow...just finished copying over.... Didn't realize how HUGE this thread had gotten...  Need to get some more motors for this.


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I tried to avoid Black friday.  I failed in the most wonderful way.  I've wanted a glass 2.6" kit forever...and here it is.



It's the most complete FG kit I've ever gotten.  Sled, harness and all.  It could be built as is...but there are a few changes I'll likely make. I wish it had welded eyebolts, and a kevlar harness.   A third CR will make building it easier.  I'll also likely make a NC av bay.   


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I'm considering ways to do the nosecone, and will likely order a couple of stepped bulkhead soonish, and add weld/forged eyebolts.

Today I got to work washing and sanding.  Usually people give this a cursory mention while building.  I've washed the parts in dishsoap and dried them, today I went back and sanded the CR's, bulkheads, and motor mount tube, then rewashed the hell out of everything with dishsoap again.   Once it dries off I'll wipe it all down with alcohol, then sand the body tubes,fins, couplers and rewash those.  It's currently below zero in my garage, and I've got no place inside suitable for sanding fiberglass.  So while I'd love to do some more today, I can't feel my feet. ><






Plan is a BRB900 for tracking, an RRC3 for DD, and a Loki 38/1200 with a K1127LB or J1026LC.  Or both.

« Last Edit: November 22, 2015, 07:24:43 PM by dbmccann »

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #1 on: November 22, 2015, 07:16:46 PM »

Back on this build..... Got a shiny new toy for the screech :)    Anyone have ideas for mounting that LED?


Wife took the kiddos to the Science Museum this morning, so I got a few hours to work.

Glued the bulk plates, the top two CR's, and sanded the fins to fit.   (also glued the nose and coupler for the PK3)  I've decided to get stepped bulk plates for the nosecones, and just screw the single plate into something mounted inside. Not sure what yet.



I really really like the size of this rocket.



And the part I hate... setting fins.  here we go!



Too much epoxy....quick!!!! grab other stuff to glue up!



Glued up the NC too.  Letting it all cure up in my heat oven/ laundry room.

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #2 on: November 22, 2015, 07:17:35 PM »
Thanks, I don't mind painting, I actually enjoy it.  It's just getting time and good weather to cooperate...  I'm still tossed up on colors for this one. 

#2 went into place this morning.   I need to work on the av-bay yet.  aside from needing welded bolts it looks fairly complete.



I went to sand the rear CR to fit....got carried away and finished up the rear end.   

I used a 1/4" dowel to coat the fin joints with aeropoxy ES6209, then coated the rear of the BT and installed the rear CR.  Once that was in I installed the aeropack with JB Weld, coating the MMT and the inside of the aeropack.  Once I tapped it into place with a rubber mallet, I used a rag soaked in alcohol to wipe out the excess JB weld inside the tube.



I removed the metal tip from the nosecone,  and knocked out the metal washer inside.   The washer was install on a 1/4" threaded rod between two nuts, inserted back into the nosecone and the metal tip screwed back on.  Later I'll line it back up and do it with a little loc-tite.   On the bottom I've got a stepped bulkplate from rocketry warehouse.  These things are slick.   Right now there's just a nut holding it on,  I'm ordering a eye nut for it soon.  Then a sled will be made for a tracker.



round two!

don't grab the wrong glass...ends badly...




Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #3 on: November 22, 2015, 07:18:21 PM »
The madcow av-bay is a little different...  I kinda like it.


Laser guided drill!  look out!

What are you doing what that sand paper near those sexy slick fillets?!?!?!?! NOOO!!!!





Man.... I really love this rocket.  It's gonna explode on the friggen pad....


3 pounds 2.1 ounces.... no recovery or electronics.   This thing should  RIP. :)

I could get it done for april,  But I've decided If I can't get it painted I'm waiting for may.   I have an idea for mine...


Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #4 on: November 22, 2015, 07:18:47 PM »
First, I took a one inch pipe, and colored a couple inches of the end with a sharpie.  Then ran it back and forth until the lines were marked on the body and fins.  1" is kind of huge.  half inch or 3/4 would work well too.  I wanted these huge :)



Then tape.   Tape EVERYWHERE.    Front, back, on the BT and fins, I put the tape right on top of the lines that I drew.  This way the tool will pull all excess onto the tape.



I used Proline 4500.   11 grams of resin to 2 grams of hardener for fillet.  (so 26 grams per fin)   mixed it up for a couple minutes, then laid it into the opening between the tape.  All the way from top to bottom should take almost all of the 23 grams.     

I keep a bit of rubbing alcohol in a cup, and dip the tool (1" pvc pipe in this case) and then lightly wipe it off.  Starting at the front I put the tool in front of the fin against the body tube,  then slowly pull back to the bottom of the fin.   This will leave a nice rounded fillet,  and a big old mess on the blue tape.     I wipe off the excess at the front and back with a paper towel soaked in alcohol,  Then carefully pull the tape so it doesn't drip.  Then wipe up all the drips and messes with a new towel soaked in alcohol.    Pulling the tape right away lets the edges go flat.  if you wait 15-20 minutes the epoxy will be thicker and you'll have very subtle ridges.

After each fillet, I clean the tool in alcohol and wipe it off, then mix the next set.   I only do 2 at a time, I've tried doing more but it runs.   3-4 hours between each rotation is more than enough.    If you look close you'll notice it does flatten out just a bit the way I do it.   If you wait for it to setup more it'll flatten less, but this is just they way I do it.

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #5 on: November 22, 2015, 07:20:22 PM »


This is actually my first time painting fiberglass.  So smooth.   Trying to get the fillets clean and smooth is driving me bonkers.  At the point of calling them good enough. 

I just need to pickup a few more cans of  Testors one coat laquer,   get the rail buttons on, and build the sleds.  Getting close....

color one on



meh....





I hit the top of the booster again right after this photo.   In a few days I'll touch up another few spots and call it done :)




Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #6 on: November 22, 2015, 07:20:44 PM »
K1127LB

J510W

J1026LC

K1127LB






EDIT: added LDRS photos

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #7 on: November 22, 2015, 07:21:21 PM »
Opps.  this didn't hit anything....landed in plowed dirt so soft we were wishing we had snowshoes.

might be a touch hot in the ass end.  JB weld bath time.



watch the video....I was clean through an open window.... but I got this sweet video grab with the cloud layer in the back...




I officially have a new favorite rocket.  :)


Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #8 on: November 22, 2015, 07:22:50 PM »
K1127


J510W


Cut the liners open.   Wow.




threw another K1127 and a J1026LC into the mix.... still processing data and photos.


Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #9 on: November 22, 2015, 07:23:20 PM »
Realized I never added my LDRS photos/video.  Added some photos on the last page of posts of the launches....heres a few more and the video of the second K1127LB.  The camera didn't work for the J1026 :(  (seems it needs to have a card in it...DOH)










K1127


J1026

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #10 on: December 01, 2015, 11:27:16 PM »
Well...now there's an idea......

https://www.madcowrocketry.com/2-6-thin-wall-fiberglass-dual-deploy-fin-can-kit/


Gonna need to grab that in 54 :)

Offline RKeller

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Re: Madcow 2.6" 38mm Screech
« Reply #11 on: December 02, 2015, 12:09:11 PM »
now that is cool!
Riley Keller
URRG
TRA#15415
L1 25 Oct 2014 Estes MDRM CTI H133
L2 25 June 2015 Rocketry Warehouse DYOK, CTI L1030RL 14.7k ft mach 1.57

I'm addicted to building stuff, rockets are just a way to get high

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #12 on: December 02, 2015, 12:34:04 PM »
Wish it was 54, 1/8" fins and 36" long.... And an entire new rocket.... Lol. 

But, just grabbing another screech booster in 54 as is would allow up to 54/2000 motors,  be a hell of an overall range from F50T to good sized K.    Herm. 

Offline dbmccann

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Re: Madcow 2.6" 38mm Screech
« Reply #13 on: December 04, 2015, 07:12:10 PM »
Yea.  So I'm definitely doing this.    This makes me so inexplicably Happy.     Gonna toss another Nosecone in the mix to make the 38mm booster a smaller rocket.


SO EXCITED.  I'm like an annoying little kid. :)

Offline RKeller

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Re: Madcow 2.6" 38mm Screech
« Reply #14 on: December 04, 2015, 07:28:01 PM »
stock or thicker fins?
Riley Keller
URRG
TRA#15415
L1 25 Oct 2014 Estes MDRM CTI H133
L2 25 June 2015 Rocketry Warehouse DYOK, CTI L1030RL 14.7k ft mach 1.57

I'm addicted to building stuff, rockets are just a way to get high