4" Black Brant II Project

Start of project - June 13, 2007
Last updated - October 13, 2007

I recently acquired a partially completed 1/4 scale Scotglas Black Brant II rocket and I have decided to document as much of the build-up as possible and offer as much information as possible on the techniques used in the construction. I also hope to do a little different paint scheme than the standard black and white checkered pattern. I have emailed the National Air & Space Museum (NASM) archives division in Washington, D.C. to see if a unique paint scheme exists for this particular vehicle.

    
The first photo is from Scotglas, the second is my rocket, and the third is from Yellow Jacket Launch Systems Web page.

Here is a copy of a photo I was able to acquire from the Smithsonian Air & Space Museum in Washington, D.C. (June 25, 2007) The colors appear to be black and possibly red on the fins, white on the body and red for the nose/payload section. This is what I was looking for in order to be a little different as well as documented. After speaking with the archives division of the Smithsonian I found out that the photo is in black and white so I am going to be doing the paint scheme as described above.

The booster was pretty much in the configuration as in the photo below except for the u-bolt and two centering rings. There was originally a single eye-bolt which I deemed unsatisfactory for a really hard recovery and decided to upgrade to a large 2" u-bolt. The fins are basic .093 G10 sheet and as I mentioned were already attached so I couldn't do much with them. I do plan to add thick epoxy filets and a layer of carbon cloth since the first thing that hits the ground it the tip of the fin and cracks in the filets are always an issue. The booster also had a 54mm Aeropack motor retainer attached. Motor retainers are great and I suggest that everybody use one. My personal favorite is the SlimLine brand from GiantLeapRocketry. The epoxy of choice is the 3M Scotch-Weld 1838 B/A Green Epoxy Adhesive (Part A and B). I have found that this epoxy is very strong and is able to bond to many different materials and has great overall thermal properties. It's a little pricey but as long as you have good tolerances on the pieces being epoxied then a little goes a long way.

The ebay is a pretty simple design using a 9" long piece of 4" coupler phenolic tubing and birch bulkheads. I have always enjoyed using rotary switches for arming the electronics and have incorporated it into this design. I also used PEM fasteners for easy mounting of multiple electronics to the ebay board. Curently, I have mounts for the Missile Works RRC2X and the RRC2 Mini. I will add a final photo of the ebay when I get the ejection charge feedthroughs mounted and possibly show the different electronic packages and how they are laid out. The ebay is pretty much in its final configuration. I have added a hole in the forward body tube to get a screwdriver in to arm the electronics via the rotary switch. I also added four 1/8" holes to allow proper venting of the ebay. After arming I will cover the arming hole with a piece of tape. This is an attempt at trying to keep the ebays I design constant in the way that I vent them. I recently changed the layout of the ebay due to a recent launch. The problem was with the 9V battery holder. One of the contacts ended up becoming loose and thus shut the altimeter off in flight when a hard shock was applied due to a recovery event. I ended up getting some heavy duty 9V battery clips and used cable ties to hold the battery to the board. For the first flight I am using the new RRC2 Mini which has separate connectors for the battery and on/off switch so the wiring has also changed a little.

  

The body tube was glassed with a small Easyglas Sock purchased from Giant Leap Rocketry. I have found that this is a great way to easily strengthen body tubes. For really strong tubes you can first apply the Kevlar Sock and then an Easyglas Sock for an almost bulletproof body tube at a reasonable cost. The body tubes ended up being 17.75" long for the forward section and 21.75" for the aft section. The BBII will be launched via a rail. Since the weight is expected to be in the 10 to 12 pound range the small rail buttons will be more than sufficient. I generally attach a nut to the back side of the body tube so that the rail button can easily be attached and removed. Rail buttons are not that expensive but when you start to have a rather large arsenal, having the ability to switch the rail buttons out does save a little bit of cash which can ultimately go into your motor of choice.

The nose cone is all fiberglass and I have positioned a bulkhead into the nose cone as pictured below. The actual one I ended up with is a little longer than the one that is pictured since I decided that I wanted the u-bolt a little higher up. I made the new bulkhead 3-1/4" in diameter and the threaded rod a little longer and immersed everything in epoxy. The nosecone already had a considerable amount of nose weight epoxied in so it should be very well balanced. Note that I have a couple of nuts along with a fender washer located at the tip of the 1/4-20 all thread to ensure a secure fit when emersed in epoxy at the tip of the nose cone. This technique I learned from Ken Mizoi of Colorado from one of his bowling ball rockets. The center rod is also tied to the u-bolt via the steel plate that comes with the u-bolt. This is very important since you want to transfer all the shock of the recovery system through the bolts and not the airframe. This principle applies to many of my rocket designs. I also try to use locking nuts when they will not be accessible after assembly.

I finally received some carbon fiber weave and have begun to do a lay-up on the fins. For any rocket that has the fins sticking down below the back end of the body tube it is a must that the fins be strengthend to some degree or you will get nice cracks in the root edge of the fin after the first flight. I decided to go with Carbon Fiber since it is one of the strongest materials you can apply. You can also go with a fiberglass cloth which will supply sufficient strength at a much lower cost. The carbon fiber runs about $32 to $45 per yard and is usually around 40 to 50 inches wide. I also used West Systems epoxy to adhere the carbon fiber to the rocket. Here is a photo of the first lay-up.

The BBII is finally getting painted. It received its first coat of primer 9/12/07. As I mentioned at the top of the page the paint scheme will be a red nose cone, white body, two black fins and one red fin all in NASON FUL-CRYL automotive paint. The booster received its white base coat on 9/26/07 and should get the black for the fins on Sunday 9/30/07. The nose cone should be getting the bright red (Formula 674) applied shortly. I have decided to fly the BBII on an Aerotech J420R Redline motor at the local ARS rocket launch on October 13, 2007. This should be a good break in motor.

      

All finished!! This is one bright rocket. The paint may be a little brighter than the original but you will definitely be able to see it in the middle of the desert. I may add some bolt patters around the nose cone and tail cone section but I just want to fly it for now.

She Flies!!!!!
  
Flight details for 10/13/2007:
Motor: J420R
Altitude: 1,517 feet
Peek Velocity: 310 ft/sec
Time to apogee: 16 sec
Temp: 65 F
Winds: 10 - 15 mph
Notes: Perfect dual stage parachute deployment and recovery. No damage. Now I need to acquire a much larger motor.
 

Specifications:
Length: 79.75"
Diameter: 4.1"
Weight w/o motor: approx. 9 lbs
Motor diameter: 54mm
Target motor: K550 or K695R
Parachute: Rocketman R9C
Electronics: Missile Works RRC2 Mini

Costs

1) Partially completed BBII - Approx. $50.00 (This includes an Aeropack motor retainer, fiberglass nose cone and tail cone, G10 fins, paper body tube, a LOC/Precision type ebay, a few miscellaneous centering rings and a forward bulkhead assembly for the nose cone)
2) PML phenolic 4" body tube - $13.00
3) 2" U-bolt from Home Depot - $2.00
4) Misc. nuts, bolts, and washers - ~$5.00
5) Easyglas fiberglass sock from Giant Leap Rocketry - $8.88
6) G10 ebay mounting board -
7) 5/16" Aluminum tube to mount the ebay board
8) Missile Works rotary arming switch - $5.00
9) Missile Works PEM fasteners (10 4-40) -
10) 9V Battery holder -
11) Two screw type wire feedthroughs from Radio Shack -
12) One yard of carbon fiber cloth $50.00
13) Nason FUL-CRYL red paint - $31.00
14) One heavy duty 9V baterry clip - $.50
12) Nason FUL-CRYL white paint (Left over from a V-2 project) - $31.00
13) Missile Works RRC2 Mini altitmeter - An alpha unit was given to me by Jim Amos of Missile Works