Cold air baffle in HPR Nuke?

[Wayco]

I had a separation flying my LOC Nuke Pro Max last weekend. The 1/4" kevlar cord pulled out of the upper CR. On this rocket the CR is only 3/8" thick between the 2.26" BT and the 38mm MMT. Not much room to mount an eyelet or a u-bolt, so I run the kevlar through a notch in the upper CR and epoxy it aft of the CR. This time that didn't do the job. Not only did the kevlar pull out of the upper CR, but the upper eyelet pulled apart a little where it mounts to the av bay, so I'm gonna replace that with a welded eyelet. But the real problem is the fin can anchor. The BT is too narrow to get my hand into, and I would like to make a stronger anchor down there anyway. So how about a baffle like I make for my smaller rockets? Bulkheads at each end of a coupler, the aft coupler would have one large BT (probably 29mm) that extends up into the coupler with a gap at the top so the gasses expand into the coupler, change directions back down and exit through several smaller BT's that are run through the upper bulkhead. Attach my anchor to the top bulkhead, tie my kevlar to the anchor and slide the whole thing down near the top of the MMT. Run a bead of epoxy on top, and it should be golden. I use this mod. on my MPR rockets with good success, and it keeps the recovery stuff from sliding down on the top of the motor.
Does anyone do this, or have any suggestions that would work along the same lines? Not too worried about weight, the rocket only weighs 1 lb. 12 oz. and I'm getting plenty of altitude flying G's and H's as it is.

 

[El Cheapo]

Go for it.

 

[EeebeeE]

I'm hoping mine holds up. I used a kevlar shock cord. Tied a knot about 5" from one end then cut a notch into the upper CR. The knot is positioned aft of the CR with the cord running through the notch. The remaining 5" of the cord aft of the knot was also epoxied to the mm tube. After that I filled the entire fin can with epoxy foam.

I built mine with dual deploy, a BRB transmitter, and it will hold a micro video camera inside positioned for a horizon view. It is configured it to be able to hold a 38mm CTI 6xl casing. I want to fly it on a CTI J520 Skidmark. Open Rocket says it will hit Mach 1.7 and reach almost 2 miles.

 

[Wayco]

My dream load for this rocket is the AT I59 longburn. Thrustcurve says 6300 ft. so dual deploy will be necessary. The I59 is also a plugged motor with no motor eject. Still saving up for an altimeter, at least I built the coupler into an av bay....

 

[grouch]

I did this very thing with my Viper IV and it worked well. I am about to start a Nuke Pro myself but I am not exactly sure if I want to do the baffle or not. I want to keep it as simple as possible with the exception of dual deploy. I actually have my eye on a J285 for my L2 cert, yikes!

Another way you can fix your situation is get one of those long drill bits and drill a hole through both centering rings and thread the kevlar out the bottom and tie a knot in it.

Do you happen to have any pics of the av bay/coupler by chance?

 

[Wayco]

I get a kick out of going back and looking at some of my early posts here. This was back when I was trying to fly HPR with a $100 a month budget. "Saving up for an altimeter" sounds different than the reality of owning over a dozen dual deploy rockets, most of which have two altimeters in them.
I hit the way back machine to refresh my memory of some of the stuff I did with "Duke Nukem", my L1 rocket. I'm rebuilding the fincan AGAIN, it's been flown so many times the ejection charges are starting to eat through the LOC cardboard tubing. This is an interesting thread because I never did add a cold air baffle, instead I used Jarret's idea and used a Harbor freight extra long drill bit and drilled through both centering rings, threaded 1/4" kevlar down and looped it around the retainer at the bottom. This time I'm making a "Y" harness out of 1/2" kevlar tape and epoxying it to the motor mount tube below the top CR. I didn't have to buy anything for this rebuild, I already had LOC 54mm body tube, 38mm MMT and CR's in my stash. I cut out the old fins from the original fincan and saved the Aeropac retainer. This morning I sanded 14 coats of paint and primer off the old fins, and cleaned out the JB weld and cardboard MMT from the retainer. Had a set of CR's and made a third one from some scrap plywood so I could hold the top of the MMT and run the "Y" harness through it. The only epoxy I have used so far is to encapsulate the kevlar strap to the MMT. I'm waiting for it to dry so I can install it into the body tube and stick some fins.
Does anybody else like to resurrect old favorites? Usually, I don't enjoy repairing rockets, but this is different with new parts mixed with old parts, and doing it all by memory. I'm amazed at how much fun I'm having with it.

 

[grouch]

Hehe, I like reading the earlier threads too. It's interesting to see how much have changed since when I started a few short years ago. It's really crazy how a persons budget changes bet time.

 

[Banzai88]

Holy thread necropsy, Bat Man! Cool to look back and see how far you've come!

 

[AlfaBrewer]

Did you ever fly this on the I59? I've got a similar sized rocket I'm planning on flying this weekend on that motor, and sims indicate a similar performance to you. I'm curious if reality met your sims.

 

[Wayco]

Did you ever fly this on the I59? I've got a similar sized rocket I'm planning on flying this weekend on that motor, and sims indicate a similar performance to you. I'm curious if reality met your sims.

I flew it twice on the I59, got some good altitude on the first flight, about 5000 ft. Highest flight I have ever gotten from a Nuke Pro Max.
Second time didn't turn out so good:

It's been rebuilt several times, usually the fincan. What hurt the most was that meltdown cost me a Dr. Rockets casing.

Edit, I have to give credit to "Skippy" (Gerald Meux) for the action shots.

 

[KenRico]

I flew it twice on the I59, got some good altitude on the first flight, about 5000 ft. Highest flight I have ever gotten from a Nuke Pro Max.
Second time didn't turn out so good:

It's been rebuilt several times, usually the fincan. What hurt the most was that meltdown cost me a Dr. Rockets casing.

Edit, I have to give credit to "Skippy" (Gerald Meux) for the action shots.

I flew a H59 in my I-Force (gForce w/38mm mmt) .. had alot more fun flying the H45 in my Saucer.

Will break out the special extended closure when i get around to min diameter 38mm .. since the attachment for the dms is sooo not budget friendly and single use to boot

I reread Wayco "origin story" on another site and amazed how more , ahem, seriously he writes now.

Kenny