Monday, December 20, 2010

Review - North Coast Rocketry Big Brute

This is a review of the pre-Estes version of the classic stubby mid-power rocket. It included a standard 29mm motor tube and flush-mount plywood fins.

Parts list:

* NC-39 (Ace) nose cone
* BT-39/17 airframe tube
* SC-2 shock cord (elastic)
* PC-2 parachute (24" rip stop nylon)
* MT-1 motor tube
* CR-39-11 plywood centering rings (2)
* TR-11 thrust ring
* LL-1 launch lug
* GOR-2 Gorilla shock cord mount (36" steel)
* SC-2NC nose cone cord (thin nylon rope)
* plywood fins (4)
* decal sheet

The instructions were quite good and included drawings. The assembly was pretty basic, being a simple 4FNC rocket. Epoxy was used throughout. Since the fins were flush mount, small holes were made in the airframe along the fin lines to form epoxy rivets. The kit included a thrust ring, which I used. In retrospect this should have been left off. I later added T-nuts for motor retention. The Gorilla shock cord mount is a steel cable that loops through a hole in the forward centering ring. This is very sturdy and makes replacement of the shock cord very easy in such a short rocket.

The kit included self-adhesive decals. These weren't very good quality and the clear portion never looked too clear. I initially painted mine dark red and added checkerboard and chrome accent strips. One one windy day, it was dragged through a freshly plowed field, which removed both paint and stickers. I stripped the remaining stickers and repainted it fluorescent orange and flat black..



The recommended motors included everything from the F20-4 to the G80-10. I have flown mine on  a wide variety of motors:

AT EconoJet F20-4, AT EconoJet F23-4, AT EconoJet G35-7, AT EconoJet G38-4, AT RMS G64-5, AT RMS G64-6, AT RMS G64-7, AT RMS G77-6, AT RMS G79-6, AT SU F25-6, AT SU F50-4, AT SU G80-10, AT SU G80-7, Ellis SU G35-6

The stock kit had a tendency to weathercock quite a bit (a 6 foot rod was recommended). As a result, I added a bit of nose weight and some rail buttons. It is now arrow straight and you really can't notice any degradation in performance. As I said, I have retrofitted the kit for positive motor retention. I also use a parachute protector (Nomex or car air bag) in place of wadding.

The shock cord is tied to the Gorilla mount and to a loop of rope which is in turn tied to the nose cone. The 24" parachute is too small for the flush mounted fins. Despite the epoxy rivets and generous epoxy fillets, it tends to strip fins (mine tries to find a rock, paved walkway, or whatever). I now use a 36" -  42" parachute.

Final update:  The Big Brute's final flight was on 6/18/2011 at MDRA's ESL-157.  It flew on an AeroTech G138-6.  The boost was really quick but, unfortunately, there was no ejection event.  It tore through a tree before encountering terra firma.  RIP.