Clone Goblin Clone

Clone - Goblin {Scratch}

Contributed by David Urbanek

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar
Manufacturer: Clone

Estes GoblinBrief:
Classic Estes kit that had unique styling, good graphics and super flight characteristics.

Construction:
I decided to clone the classic Estes Goblin. It was a popular kit for many years with Estes, and I never owned one because I couldn't afford the D motors.

The plans were from the original Estes instructions as detailed on the JimZ website. I got the parts from various places. The biggest expense was shipping, so I bought parts for three kits. The other two kits were given away at the UROC Christmas party.

The nose cone was part BNC55-AO from Balsa Machining Services. It's not a custom nose cone. The quality was top notch and the service was fast, as is usual from BMS.

The body tubes (BT-55 and BT-50), centering rings and engine blocks were purchased from Aerospace Specialty Products. The ASP body tubes are white, so finishing is easier than with brown tube. The centering rings were good quality and received in good order. The main body tube is 9" long. The motor mount is 2.75" long.

The motor hooks, balsa fin material and 3/16" launch lug were from a local hobby store, Douglass Models. The motor hooks and launch lugs are standard Estes hooks. The fin material is 3/32" balsa.

For the shock cord, I deviated from the Estes plans. The anchor is Kevlar looped around the forward centering rings, and the shock cord is nylon cord. The Kevlar was purchased from Pratt Hobbies. Also, the nose weight is fishing weights. I put 0.75 oz of weight in the nose. This makes my Goblin stable up through an F24 motor. Fishing weights were from a local bait shop.

The decals were purchased from the JimZ website as well. They were absolutely great. He also threw in a set of decals for an Estes Blue Star, so I that one too (but that's another review).

I also added a 9" Top Flight chute for recovery.

In the spirit of a clone, I decided that there would be no epoxy on my Goblin. I built it pretty much per directions, except for the shock cord anchor. Since my nose weight was more than the basic Goblin, I also opted for a 9" nylon chute. This brings it down much slower than a streamer, but still pretty fast.

The fins roots were reinforced with used dryer sheets. A strip of dryer sheet was applied to the fin root with yellow, aliphatic resin glue (SiG Bond). This is a very strong glue and the strong fibers made the fins roots very strong. It took a lot of sanding to make it smooth though. The nose cone weight was added by drilling 2 holes in the nose cone and adding fishing weights. After the weights were in place, a dowel was cut and glued in to fill the hole.

The shock cord anchors to the motor mount. A length of Kevlar was tied around the forward centering ring before the motor mount was glue in place. The Kevlar extends about 6" out of the body tube. Then about 48" of nylon cord was tied to the Kevlar and the screw-eye in the nose cone base. A loop was tied in the nylon near the nose cone and this is where the chute is attached.

Finishing:
Sealing the fins and nose cone was done as I usually do it. Hobbylight balsa filler is applied liberally to the surfaces with my finger, rubbing the stuff into the grains. Then I sand it smooth with very fine sandpaper. This is followed by 2 or more coats of sanding sealer, sanding with very fine sand paper between coats. This fills all the grain and makes things very smooth.

In fact, I rub the Hobbylight into the body tube seams as well. After sanding, it speeds up the primer/sanding time.

I sprayed the whole rocket with two layers of Plastikote Scratch Filling Truck Primer. The first coat was sanded almost all the way back, the second was just sanded to smooth it. I use 3M sanding sponges for this step.

Next two coats of Krylon flat white was applied to give a nice even undercoat. Sand between each coat with very fine sanding sponge. Then I sprayed two coats of Krylon Yellow. Then I masked it off and sprayed one fin and the nose cone Krylon Gloss Black.

I then applied the decals. They went on very easily and covered perfectly.

Finally, airbrushed Testor clear gloss on the whole thing, to make it evenly glossy. The results were catalog perfect.

Construction Rating: 5 out of 5

Flight:
Prepping for flight is easy. Pull the shock cord all the way out and put a generous amount of wadding in the tube. Z-fold the shock cord and slide that into the body tube. Pull the chute into a peak, z-fold the shrouds and place them on the base of the chute. Z-fold the chute, roll and slid it into the body tube. Put the nose cone on. The motor is just a matter of popping it into the motor mount. Simply. I've flown it three times on D motor. Aerotech D9-7 is fast and high, deploys a little after apogee. Aerotech D15-7 is very fast, high and just about right for delay. Estes D12-7 is fast and high, delay is just about right.

On all the D flights, the rocket was pretty much invisible until the chute came out. Keep your eye on this one, or you'll lose it fast. Unless you're eagle eyed, I'd save this rocket for blue sky days.

I've flown it once on an 18 mm motor with an adapter. The C6-5 was good, but seemed pretty anemic after seeing the D flights. This is a good motor for parks and such.

The rocket lifts off very fast, and there is a fast spin to it which is visible during coast.

Recovery:
I've flown it three times with the 9" chute, and once with a streamer. I really regret the streamer flight because the rocket came down very fast, the nose cone pulling everything behind it. It landed hard, nose cone hitting first, and my little Goblin still shows the scars of that landing. The 9" chute brings it down fast, is more visible and a lot gentler.

The Kevlar/nylon system is holding up very well. This rocket gets up a good head of steam. If there is any wind, it doesn't slow down too much. I wouldn't use elastic cord, unless it's really long, because you're going to get dings in the nose cone and body tube.

You really need to watch this carefully, it's not a small field rocket.

Flight Rating: 5 out of 5

Summary:
The Goblin is a favorite upscale. You can get upscale decals from JimZ or Tango Papa. There are no scale nose cones for it in larger sizes, though. Most people go with an 'close enough' ogive nose cone from LOC/Precision. The rocket is deceptively sturdy and very stable. It's speed and altitude usually startles people.

Overall Rating: 5 out of 5

Flights

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