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REV 2.4 - Sun Apr 10 20:47:36 2011

Thrustline Aerospace
Zack Attack
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SPECS: 21.5" x 1" - oz
ROCKSIM FILE: Right Click to Download
SpaceCAD FILE: MISSING - please submit here
REC'D MOTORS: A8-3, B6-4, C6-5

(Contributed - by Bryan Penfold - 10/20/03)

This is a medium priced skill level 2-3 rocket with a payload section as designed by Thrustline Aerospace.

Parts included with this kit were a balsa nose cone and transition piece, a body tube plus a smaller upper payload tube, engine tube, engine hook, centering rings and block ring, launch lug, balsa fin stock (not pre-cut), a screw eye and parachute kit, Kevlar thread and elastic shock cord for recovery.

Seven sheets of instructions plus a fin template sheet come with this kit and include photo illustrations. The instructions were useful but the photos were dark and less helpful than illustrations would have been. First up was construction of the motor mount. The centering rings were too snug for the tube, but rather than sanding, I just removed the outer layer of cardboard from the rings which were delaminating anyway. A gap cut in the centering ring allows the engine hook to spring. This gap weakens the integrity of the ring however, and speeds the delamination of the cardboard. The engine hook is then taped to the mount to hold it in place. An engine block ring is also included, but it seems a little like overkill. The Kevlar cord wraps around the motor mount and threads up through the tube for the recovery system. After inserting the motor mount into the body tube, I found that the hook would not spring far enough to allow engine insertion and removal, so I had to cut a slot out of the body tube to allow for this. Also, the end of the hook was sharp enough to cut your finger and I opted to use a file to smooth it. The fins are not laser cut and you must trace them out on the balsa stock and cut them yourself. A fin positioning guide is included, but I used the Estes Marking Guide instead. The six fins (three lower and three upper) were not hard to align and I used pin holes through the tube (glue rivets) to secure them better. The body tube was somewhat soft with the interior spirals showing through as bumps. I had not seen this ever occur before. The instructions direct you to draw a line for the launch lugs, but then direct you to glue them to the side of the fins. The nose cone and transition did not fit inside the body tube and required a bit of sanding. The mylar parachute was unmade, and no instructions were included for its construction. I substituted a 12" nylon parachute from Thrustline for the mylar one included (Thrustline makes wonderful ripstop nylon chutes). I would rate this kit a 2 on construction and finishing due to the poor fitting parts and their quality. It's about as close to scratch building a rocket as you'll ever get with a kit.

The quality of the balsa was poor and I should have spent more time filling it. I used about three coats of sanding sealer with little effect. Paste filler would have worked better. The nose cone wood was so weak, I actually broke the tip of it off while finishing the rocket, but it glued back on nicely and with a little filler, wasn't noticeable. After initial painting with chrome spray paint, I painted one fin with fluorescent orange, then sprayed everything with multi-colored glitter. After several coats of clear coat to cover the rough glitter, I attached the single sticker for identification and clear coated the whole thing again. Even with all the problems I encountered with this kit, the unique design of the Zack Attack was a welcome addition to the fleet.

Construction Rating: 2 out of 5

For the first flight, I used an Estes B6-4 engine. Flight preparation was typical of simple rockets using wadding. It flew very straight off the pad to an estimated height of 700 feet and landed about 200 feet from the pad using a 12" nylon parachute in 1-5 mph wind. Some damage occurred to the end of the body tube from recoil of the payload section. For its second flight, I used an Estes C6-5. Again, it flew very straight off the pad and reached an impressive height of about 900 feet, but landed 500 feet from the pad in 1-5 mph wind and again suffered body tube damage from the recoil. If I get 5 more launches with this rocket, I will be surprised.

Shock cord is attached to Kevlar thread running through the body tube from the engine mount. Assembly of the recovery system was similar to that of Quest rockets. A 12" parachute seems about right for this rocket, there has been no damage from landing. The damage is occurring during the ejection phase.

Flight Rating: 4 out of 5

The main PROS of this rocket are the way it looks and the way it flies. The many CONS include substandard quality of materials and recurring damage during the ejection phase. I will give Thrustline Aerospace another try, and I recommend that anyone else who likes a challenge do the same.

Overall Rating: 3 out of 5

(Contributed - by Matthew Bond [Who's Who Page] - 08/05/09) (OOP) Thrustline Zack Attack

Having recently re-energized my addiction to rocketry, I was faced with the task of recreating the core of my previous rocket fleet. Thinking back, I realized that a great many of the rockets that I liked to fly were the designs of John Rowan-Stern at Thrustline Aerospace. Unfortunately, Thrustline was no longer in business this time around (a situation that has since changed) and so with RockSim and EMRR as my primary resources, I began to clone my favorites.

The Zack Attack was one of Thrustline's earliest designs. It consists of a BT-50 base transitioning to a BT-20 payload section with 2 sets of fins, flies on 18mm motors, separates at the transition, and recovers on a 12" chute. Like many of John's designs, the Zack Attack "fit" my eye in terms of size, scale, and line, and with the RockSIM file downloaded from EMRR, I started my build.

The parts needed to clone the Zack Attack are simple and readily available. A fin template picture is included with this review so anyone can build it. The following parts are required:

(OOP) Thrustline Zack Attack
  • BT-50 Body Tube – 12.75 inches
  • Balsa Transition BT50/20 – I used a Semroc TA 2050A
  • BT-20 Body Tube - 7 inches
  • Nose Cone – BNC-20N
  • BT-20 Motor Mount Tube – 2.75"
  • Centering Rings CR20/50 – I used the heavy paper type
  • Standard length engine hook
  • Thrust Ring – CR-5/20 Centering Ring
  • 3/32" Balsa Sheet
  • Shock Cord System – I used 24" of 100lb Kevlar and 24" of 1/8" sewing elastic
  • Launch Lug – 1/8" x 2"
  • Small Screw Eye – Attaches shock cord to payload section
  • Recovery Device – Your choice, the original kit came with a 12" Mylar parachute

The Zack Attack was a fairly simple build. It's maybe just a tick harder than skill level 1 due to the fact that you need to align two sets of fins, but there were no real tricks and I would imagine that anyone who has built a kit or two could get this done without any trouble. My standard routine was to put together the engine mount first, which included cutting a slit in the motor tube for the hook, gluing the thrust ring into the forward end of the motor tube, securing the engine hook to the motor tube with a wrap of masking tape, and then glued the centering rings to the motor tube approximately 1/2" from each end of the tube. At this time I also attached the Kevlar shock cord to the motor mount by tying it around the motor tube between the centering rings then cut a small notch in the outside of the forward centering ring to allow the cord to reach the front of the rocket. Finally, I reinforced the centering ring to motor tube joints with glue fillets.

While the motor mount glue was drying, I cut out the fins, making sure I knew where the leading edge was to get the grain orientation right. A sharp knife and a metal straight edge made this task very simple. The two sets of like fins were stacked together and sanded so that they were identical, and the leading and trailing edges were rounded off.

Installing the motor mount was next. First, I threaded the Kevlar back through the motor tube to keep it out of the way, and test fit the motor mount to make sure it slid easily into the body tube. Next, a ring of glue was swabbed inside the body tube near where the forward centering ring would rest, and the motor mount slid into position with the aft end of the motor tube even with the aft end of the body tube. After the glue was dry I added a fillet to the aft centering ring where it meets the body tube. At this point I sanded the body tube to scuff up the glassine coating, which I believe helps the gluing/finishing process.

(OOP) Thrustline Zack Attack There are several methods for marking the body tube for fin/launch lug placement. I usually save the fin marking guides from all the kits I build so a rarely have to come up with a new one. I used a section of small aluminum angle from a local hardware store to extend my fin/lug lines. The aft fins for the Zack Attack were attached even with the aft end of the body tube and the forward fins were attached 5.75" from the aft and of the body tube in line with the aft fins. The launch lug is cut into two pieces which were attached 1" and 6.5" from the aft end of the body tube. The fins and launch lug were attached with wood glue using a double glue joint, and reinforced with wood glue fillets.

The forward payload section is assembled according to your own plans for flying this bird. I personally don't have any plans to fly a BT-20 sized payload so the nose cone and transition were permanently glued in place. The screw eye was attached to the transition by screwing it part way into the base, removing it, adding a large drop of medium thickness CA glue and then screwing it all the way down. Final assembly included tying the elastic cord to the Kevlar line and then tied to the nose cone with a drop of thin CA glue on all the knots.

My original Zack Attack kit did not come with any decals or recommended paint scheme--heck, the instructions were in black and white so you couldn't even steal John's colors. I originally planned on copying the scheme of my original Zack Attack, but after I got the first coat of color on the fins, I went a different route and was happy overall with the results. I used Elmer's Wood Filler to add smooth fillets to the fin and launch lug joints. The nose cone, transition, and fins were sealed with two coats of Elmer's Wood Filler thinned with water and sanded smooth. My standard finishing routine is 2 coats of primer (Rustoleum Painter's Touch Sandable Primer) and then 2 coats of Krylon spray enamel, working down to 400 grit sandpaper before the final coat. I have had decent success using standard 3M masking tape for my paint jobs. As long as I always cut a new edge on a clean cutting surface and remember to rub the edges down before the first coat of paint, the results have been good.

Construction Rating: 5 out of 5

(OOP) Thrustline Zack Attack

Recommended motors for the Zack Attack include the standard range of black powder 18mm Estes/Quest Motors. I have yet to find the courage to put an 18mm composite motor in my Zack Attack, but I'm sure that would be quite a ride. Flight preparation is standard: add some wadding, load up the recovery device, install the motor, insert the igniter, and head to the pad. My original Zack Attack flew six flights in all kinds of conditions. The majority of those flights were with C6-5 motors which will push this rocket to around 900ft. My new Zack Attack has flown on all the recommended motors, and while it is a nice small field flier on an "A" or "B" motor, a C6-5 is still hard to beat. The nice thing about this rocket is that it looks good on the pad, it looks good in the air, and it won't get completely out of sight on BP motors so you'll be able to fly it over and over.

The original kit came with an unassembled 12" Mylar parachute, which held up through many flights with only a few small burn/melt through spots. Even though the chute is packed into the lower section of the rocket there is still plenty of room to keep it clear of the worst of the ejection charge. My new Zack Attack clone uses a 12" plastic chute from Semroc because that's what I had on hand and recovers just fine, even in moderate winds. The only issue I have ever had with this design is that when the forward payload section is deployed by the ejection charge, it is susceptible to damage from hitting the aft section/fins. The problem is compounded on windy days since the design is a bit overstable and will arc into the wind, leading to faster deployments. My original Zack Attack picked up a couple nice creases and paint marks on the forward section due to deployment strikes. So far my new Zack Attack has come back clean, even from some arcing flights on windy days.

Flight Rating: 4 ½ out of 5

One of Thrustline's earlier designs, this one hasn't been re-introduced yet, so is still a good candidate for a cloning project.

PROs: Basic rocket that is a small step up from 3FNC with a great "look", good performance, and simple construction. This is a pretty well thought out design. The motor selection and recovery system are well matched to the size of the rocket.

CONs: None really, except for the fact that you can't buy it anymore (for the time being...) The forward payload section is susceptible to damage during the ejection event.

Overall Rating: 4 ½ out of 5

[Submit your Opinion]

02/05 - "This was my second rocket from Thrustline. I was surprised to read that there was an ejection problem, as I have had none in eight flights. This rocket flew very well and in a straight line for me, except for one flight on a windy day. I use a C6-7 with this rocket" (G.)

10/03 - "In an effort for continuous improvement, we have made a few changes with this particular kit. We have replaced the "paper type" centering rings with laser cut rings. Also, the instructions have been corrected to show the proper launch lug placement. Although it may appear to be "redundant" we will continue to include an engine block. One final note, in an effort to bring "building" back to the hobby, occasionally the builder must sand, adjust, or cut some items. This is in keeping with the philosophy of building as opposed to just assembling which in turn improves not only the building technique, but also improves the over all understanding of construction." (J.F.R.)

[Enter Rocket Specific Tip]

"" (x.x.)

[Enter Flight Log]
Date Name Motor Ejection/
Wind Notes
09-25-2004 Matthew Bond Est SU B6-4 Apogee - NC Up 0-5 mph winds Event: PACK 688 Rocket Derby
- First Flight! Nice straight boost and coast, just stalling out at ejection. Chute looked only partially inflated but rocket descended fine. Nice cut in the nose cone that matches up with one of the small upper fins.
10-02-2004 Matthew Bond Est SU B6-4 Apogee - NC Up Light winds - Quick and straight off the pad, just stalling out at ejection. Good chute, no drift, caught it on the fly. No damage.
10-11-2004 Matthew Bond Est SU C6-5 Apogee - NC Down 5-10 mph winds - Launch rod angled into the wind. Fast, high boost, arcing over at ejection. Good chute, spinning on the way down. Caught it on the fly. No damage, payload section tangled in shroud lines.
04-09-2005 Matthew Bond Est SU C6-5 Apogee - NC Down 0-5 mph winds Event: QUARK Section Launch
- Fast, straight and high. Just tipped over at ejection. Chute did not unfurl for 2-3 seconds. Minimal drift, grass landing about 100 ft away. Payload section picked up a nice crease from one of the fins.
04-09-2005 Matthew Bond Est SU C6-5 Apogee - NC Up 5-10 mph winds Event: QUARK Section launch
- Fast, high boost, a little bit into the wind. Just stalling out at ejection. Good chute, long walk. Tall grass landing, no damage. Payload section seem to be sound.
06-21-2009 Matthew Bond Est SU C6-5 Apogee - NC Up 5-10 mph winds Event: Southern Thunder
ZAClone - First flight of my new Zack Attack. Nice boost, fast straight and high. Arcing into the wind at ejection. Good chute, long walk, grass landing, no damage. Great flight!
06-30-2009 Matthew Bond Est SU A8-3 Apogee - NC Up 5-10 mph winds Flight Picture ZAClone - Short. quick boost, decent altitude with this motor. Stayed nose up, kind of holding into the wind at ejection. Good chute, fair amount of drift, grass landing, no damage.
06-30-2009 Matthew Bond Est SU B6-4 Just Past (1-2sec) 5-10 mph winds Flight Picture ZAClone - Cranked the launch rod into the wind for a high fast arcing flight. Just barely over the top and heading down at ejection, fairly hard deployment. Good chute, long walk, grass landing, no damage.
07-11-2009 Matthew Bond Est SU C6-5 Apogee - NC Down 5-10 mph winds Flight Picture ZAClone - Hight fast boost, arcing into the wind, just pointed nose down at ejection. Good chute, long walk, grass landing, no damage.
08-01-2009 Matthew Bond Est SU C6-5 Just Past (1-2sec) 5-10 mph winds Flight Picture ZAClone - Angled the rod into the wind. Nice arcing boost, fast and high, heading downhill at ejection. Pretty hard deployment, good chute, wind brought it back close. Grass landing, no damage.
10-17-2009 Matthew Bond Est SU B6-4 Apogee - NC Up 10+ mph winds Flight Picture ZAClone - Nice boost, fast and straight. Nose up at ejection, good chute, long walk, grass landing, no damage.
11-21-2009 Matthew Bond Est SU B6-4 Just Before 0-5 mph winds Flight Picture ZAClone - Great boost, fast and straight. Not quite done climbing at ejection. Good chute, no drift, walked under it and caught it on the fly, no damage.
11-28-2009 Matthew Bond Est SU B6-4 Just Before 0-5 mph winds Flight Picture ZAClone - Nice boost, straight and fast. Slowing down, still climbing at ejection. Good chute, minor drift, grass landing, no damage.
05-08-2010 Matthew Bond Est SU B6-4 Apogee - NC Up 10+ mph winds Flight Picture ZAClone - Nice flight on a windy day. Quick straight boost, arcing into the wind at the top of the climb. Nose up at ejection. Good chute, long walk, grass landing, no damage
09-26-2010 Matthew Bond Est SU C6-5 Apogee - NC Up 0-5 mph winds Flight Picture ZAClone - Great boost, straight, fast and high. Stalling out, still nose up at ejection. Good chute, long time coming down. Shortest walk of the day, about 15 feet from the pad. Lakebed landing, no damage.
01-28-2006 Matthew Bond Est SU C6-5 Apogee - NC Down 10+ mph winds RIPEvent: QUARK Section Launch
- Fast and high, not quite straight up, but not into the wind either. Arcing over at ejection. Good streamer, medium sized walk. Grass landing, picked up a nice chip on fin leading edge. Status: Retired
04-03-2005 Andrew Grippo Est SU A8-3 Apogee - Perfect 5-10 mph winds Zach Attack - Good flight and recovery. Built this kit because my grandson is named Zachary and I just had to have it. This is a nice kit that flys well and looks good.
11-03-2005 Andrew Grippo Est SU A8-3 Apogee - NC Down 5-10 mph winds Zach Attack - Low and slow but fun to watch. Good deployment and recovery.
10-01-2003 Bryan Penfold Est SU B6-4 Apogee - NC Up 0-5 mph winds - Good flight, straight up. Approx. 700' altitude, landed about 200' from pad, slight damage to upper body tube from ejection.
10-04-2003 Bryan Penfold Est SU C6-5 Apogee - Perfect 0-5 mph winds - Good flight, straight up. Approx. 900' altitude, landed 500' from pad. More damage to upper body tube from ejection.
10-14-2003 Bryan Penfold Est SU B6-4 Just Before 5-10 mph winds - Good flight, straight up. Approx. 700' altitude, landed about 500' from pad in a tree. Later recovered and found a 6 zipper in body tube. Will repair and fly again.
11-02-2003 Bryan Penfold Est SU C6-7 Didn't Record 0-5 mph winds - Good engine for this rocket, longer delay seems to help. Rocket angled off pad somewhat to approx. 850 ft, landed 45 ft. from pad, no damage
07-05-2003 John Rowan-Stern Est SU B6-4 Apogee - NC Down 0-5 mph winds - Good flight. Changed wadding to heat shield for next flight. Landed 200 feet from pad. No damage.
07-05-2003 John Rowan-Stern Est SU B6-4 Apogee - Perfect 0-5 mph winds - Straight up, no weathercock. Ejection perfect. Slight crimp in upper body tube. Will extend shock cord. Landed close to Pad.
07-05-2003 John Rowan-Stern Est SU C6-5 None - Unknown 0-5 mph winds - Great flight. Nice and high. Extra shock cord did the trick. No damage. Landed 300 feet from pad.

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