Madcow Nike-Asp Build

[Keenan Cox]

After a life-induced hiatus from rocketry, I found myself with the bug again. A couple years back in, building and flying as time allows, I decided to venture down the path of staging again. The timing of the Madcow release last year made it all too hard to refuse, so I picked up a Nike-Asp in the first run of kits. It has been sitting in my build pile since, waiting for a good time to build. My previous experience with staging has ranged from Estes black powder to a larger J and K powered project. Not extensive by any means, but have touched on multiple aspects of staging with relative success, and learned a lot along the way. Now that I have officially started construction, I wanted to do my best to document the project and seek advice from those smarter than myself.

There are a few aspects of the design I am still sorting out, but have some rough ideas that could conceptually work, I think. I will address these hangups in later posts, and will be taking my time with this build, so plenty of time to make sure it is done right. I will be taking my time with this build and doing everything I can to increase my odds of success with it. I hope to have it fully built and flyable within the next year or so, but possibly LDRS if that is feasible. Thank you all in advance for your patients! There will be plenty of new knowledge needed on my part, and working at such a small scale will introduce plenty of challenges. I'm looking forward to this build, and what I can learn from it.

 

[Keenan Cox]

I'll be starting with the sustainer, as it has the biggest hurdles for me. The limited space for recovery, altimeter and trackers will be the most challenging portion of this build. I have explored several options, and am still weighing the merits of each.

At this point, I am still waiting on a couple small items to show up, and when they do, I'll be able to start bonding pieces together. Current plan is to use Rocketpoxy for the vast majority of the construction, and lighter epoxies where appropriate.

So far, I have sorted out the dry fit of the components. Fin slots were too narrow, so I widened those with a thin bar file. The fin tabs are too long, and will need to be sanded down. Additionally, the cuts on the tabs were quite round, as shown in the parts photo. These were squared out for a better fit. I plan to run the staging electronics from above, so I will have a wire running down the side of the MMT for the igniter, and possibly separation charge. I plan to notch in a small channel along the MMT, as well as building up between the MMT and airframe to help guide the leads. It's not monumental progress, but I have a passed the initial hurdle of starting the build. Once the ball is rolling, it's much easier to keep building for me.

 

[Keenan Cox]

I was able to start assembling the MMT this evening. Fore and aft centering rings were slotted to allow for staging wiring to pass through. I filed a small, curved channel down the length of the MMT to allow for a smidge more space. The fore centering ring was notched on the opposite side for the shock cord. This required cutting the ring into two pieces and aligning the parts with the electronics channel. I am using 500# Kevlar from Vander-Burn for the sustainer. It's small and strong enough for this small of a rocket.

Rocketpoxy was used throughout, then wrapped with electrical tape to keep everything flush with the MMT. I clamped the fore centering ring along the shock cord to keep the assembly still while it cures. I'll update when the tape comes off. Next post will be regarding recovery of the sustainer. I plan to do a test flight or two as a single stage before I do a full-up 2 stage flight.

 

[Keenan Cox]

Due to the finite space in the sustainer, I am trying to be efficient with what is available. I have weighed two different methods of dual deploy for this, and both have their merits. At this moment, I am leaning towards a more traditional layout, with the altimeter bay being in between the drogue(less?) and the main, with a tracker located in the nose. The second method would be to deploy everything at apogee, with a cable cutter and electronics located in a single bay extending below the nose cone. I'm less inclined to use the second method, as I have had less than ideal results in the past with deployment here, though I have never used a purpose-made device either. I am open to suggestions here, and if a third alternative makes sense, I would be open to pursuing that too.

I will be using a Raven in the sustainer, which allows for safe cutoffs in the event of a less than ideal boost. It has enough channels to fire a separation charge, light the sustainer, and deploy both apogee and main events. My plan (currently) is to separate the wires from the altimeter using filed-down JST junctions at apogee. I'm expecting good results with drag separation at this point, as the interstage coupler is loose enough that it falls out under its own weight, and could easily be painted with epoxy or the like to give it a little more grab. I will likely paint the inside with a high temp epoxy to provide a little extra protection in case it does not come apart before the sustainer lights. A separation charge is still on the table, but if I don't outright need one, I'd prefer to skip it to keep the overall prep a little simpler. I'm still working on the overview at this point- any suggestions are welcome and encouraged. Can't wait to get this one up in the air!

 

[Dipstick]

Not sure how long you've been in or out, but we're you flying in Montana back in 2010? I visited a launch there at the start of a road trip and I think we met. I remember a Tomahawk 2 stage or something close to a Tomahawk anyways.
I have always enjoyed the challenge of 2 stage, looking forward to the build!

 

[Keenan Cox]

I was! I had a Terrier-Sandhawk that I flew a few times before I had some electronics issues and the majority of it was destroyed. Never figured it all out, but it taught me a lot about how to build the rockets all the same. Thanks for reaching out!

 

[Cameron Anderson]

What's your booster ISC set up look like? Any electronics in there? I just got the Nike Apache and I'm shocked how small it all is.

 

[Keenan Cox]

I haven't focused as much on the ISC yet, but have a rough idea of how I want everything laid out. I will likely run a Perfectflite Stratologger CF with a line cutter, though may simplify a bit and use a JLCR for opening the main. The booster won't be going nearly as high, but still high enough that I would prefer a dual deploy setup. I'll have a tracker and altimeter in the ISC regardless. It could definitely be flown in a manner where a single altimeter in the sustainer could provide the full operation of the rocket, and for low altitude flights, that may still happen. I'll see if I can't mock something up before long.

Other news, I have roughed in my sustainer altimeter bay, and, when time allows, will start gluing fins on the sustainer. I was in the backcountry for a couple nights over the weekend, and the previous week turned into prep for that trip, so I haven't made much progress in the last 7-10 days. Smokey skies and bad air are keeping me inside more, so hopefully I'll be able to make more progress on the build soon!