Hijacker Build

qquake2k

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Well, I received my Hijacker kit from Mercury Engineering last Friday. My initial impression is that it's a good quality kit. I was a little surprised at how thin the body tubes are, but I suppose if they were thicker it would make the rocket that much heavier. The instructions are very clear and concise, and easy to follow. Lots of good drawings make the steps very clear.

I was originally going to build it with a 2x24mm cluster motor mount, and even ordered the cluster mount with the kit. But I decided to build it with the single 29mm mount, so I can use F and G motors in it. I'll save the cluster mount for another rocket. I also ordered the 24mm to 29mm adapter, but I don't think I can use E9's with this rocket. The advertised weight on the Hijacker is 16oz, and the E9's maximum liftoff weight is 15oz.

I'm excited about the rocket, so I dug right in. I put the motor mount together per the instructions, and used carpenter's glue. I've been around woodworking all my life, and am very confident in the carpenter's glue's strength. The motor mount didn't come with a thrust ring or motor hook, of course, but did come with a length of foil tape to wrap around the end of the motor tube. This is to prevent damage to the tube from the masking tape used to hold the motor in. The centering rings are laser cut fiber, and seem plenty strong enough.

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qquake2k

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The next step was to put together the tube coupler/ejection baffle. The ejection baffle is nothing more than two fiber discs that are glued inside the tube coupler. The discs each have matching half moon cutouts in them, and they are glued in so that the cutouts are opposing. I'm not sure how effective it will be, but I'm sure it will help. The Hijacker has a unique (to me) shock cord mount. It consists of a small #6 eyebolt, two flat washers, and a nut. The eyebolt is installed in a precut hole in one of the baffle discs. The instructions say to put glue on the nut after you tighten it, but I used Loctite. Then I got paranoid, and added my own nylon locknut.

The discs fit very loosely in the coupler, but I got them glued in. After the glue set, I put thick fillets on both ends.

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qquake2k

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The fins are laser cut from what looks to be good quality light ply. I lightly sanded both sides of each fin, and sanded the root and trailing edges. I rounded the leading edges.

One of the body tubes comes premarked with fin lines, launch lug lines, and the places to cut out for the fin tabs. It looks like the markings were done with a pencil and template, but they appear to be accurate. I cut out the fin slots with an Xacto knife, which was very easy.

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qquake2k

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I test fit the motor mount in the body tube, and it was a little tight. I sanded the inside of the body tube and the centering rings to get it to fit a little looser. I put a line of glue inside the body tube above the fin slots, slid the motor mount halfway in, and put a line of glue just inside the bottom of the tube. I slid the mount in until the motor tube was even with the bottom of the body tube. I sat the body tube upright until the glue had time to set, then put a heavy fillet around the bottom centering ring.

I got paranoid about the shock cord mount pulling out, so I mixed up some 5 minute epoxy and epoxied the heck out of the baffle disc with the eyebolt in it. It should be plenty strong now.

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qquake2k

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Gluing the fins on is pretty straight forward, and the tabs are just the right length to contact the motor mount tube. Like I said, I'm very confident about carpenter's wood glue strength. But with the cold (for us) weather we've been having, the glue was taking forever to set up. So I decided to use 5 minute epoxy for the fins, and am very glad I did. I've never used epoxy extensively, and like how the 5 minute set up quickly on the fins, and love the fillets it produced. I used epoxy to glue on the launch lugs, too.

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rockie

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Looking good !
I like that they premark the tube and slots becouse that is usually the least fun part in building a rocket apart from sanding mayby :)
 

DM1975

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Very nice. Get some AT 24mm motors and you can fly it on E's then. I used wood glue on my Grave Danger and it has held up wonderfully. I am also a firm believer in wood glue. I like epoxy for fillets and bonding dissimilar materials together, but for wood on wood or paper, wood glue can't be beat.
 

qquake2k

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Very nice. Get some AT 24mm motors and you can fly it on E's then. I used wood glue on my Grave Danger and it has held up wonderfully. I am also a firm believer in wood glue. I like epoxy for fillets and bonding dissimilar materials together, but for wood on wood or paper, wood glue can't be beat.

Do you think an E15-4 would wortk?

I agree about the wood glue. I personally have seen hardwood break before the glue joint broke. Amazing stuff.
 

exprditer789

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The best thing to do is rocksim it and then you can mess around with a bunch of different engines.Alex:D
 

DM1975

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Do you think an E15-4 would wortk?

I agree about the wood glue. I personally have seen hardwood break before the glue joint broke. Amazing stuff.

It says it will work with an E30-4, but I don't know about an E15-4. I agree about using rocksim to find out a good motor combo. It is a very invaluable tool.
 

qquake2k

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I'm not normally one to spend time sealing wood fins. I usually spray them with primer, sand them, paint them, and call it good. But I've been hearing a lot here about using Elmer's wood filler, so I thought I'd give it a try. I thinned some with a little water until it was slightly thinner than syrup. I brushed it on with a 1" paintbrush, and let it dry. It sanded very easily, and I was really happy with the result. I'm sure part of it was the tight grain in the plywood (vs. balsa), but it was easy and the fins are pretty smooth. I suppose I could have done a second coat and gotten them even smoother, but it's good enough for who it's for. I sprayed the fins and lower body tube with primer, then sanded off some rough spots.

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qquake2k

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Last night I glued in the coupler/baffle, then glued the body tubes together. The kit came with a very long 1/4" elastic shock cord, which you're supposed to tie onto the eyebolt. But I ordered some tubular Kevlar that I want to use instead, but it's not here yet. So I tied a piece of string on it that I can use to pull the Kevlar through the eye. I wanted to primer the entire rocket yesterday, since it was sunny out, but I ran out of time. A little epoxy squeezed out around the body tube joint, which I smoothed with a finger. I wanted to sand it before I paint it, but it was still slightly tacky, so I thought I'd better let it set for 24 hours. It's a decent sized rocket, and I can't wait to finish and launch it!

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qquake2k

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Very nice looking. I am going to have to add this to the want list.

I really like the looks of it, too. I like the length and width, and the shape of the fins. It's on sale for a great price right now, too. I'm going to paint it black, but I think I'll paint the nose cone gold, with some gold highlights on the fins. I think that'll go very nicely with the decal.
 

qquake2k

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You know, I was reading about zipperless recovery systems last night, and it occurred to me that the Hijacker with its baffle, would be perfect for it. Maybe I'll try it with the Integrator when I get it. If it ever goes on sale, that is.
 

qquake2k

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The sun peeked out today, so I decided to primer the Hijacker. I haven't painted a rocket this long since the Mean Machine I built as a teenager. I made a support for the open end of the rocket, and used a dowel in the motor mount to suspend it for painting. I was able to rotate it as I sprayed on the primer. Worked out pretty good. Like a rocket rotisserie! LOL

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qquake2k

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After the primer dried, I decided to fill the seam between the two body tubes, because it was so prominent. I used the Elmer's wood filler on it, which worked pretty good. It dried fast and I was able to sand and primer it this afternoon. It's far from perfect, but it is better. It's supposed to be sunny again tomorrow, and if it is, I'll put on the first coat of black. I know the finish is nowhere near as good as most of the rockets I see here, but like I said before it's good enough for me.

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qquake2k

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Well, last Thursday was paint day. I started by painting the nose cone, first few inches of the body tube, and the fins gold. After the gold dried, I masked where I wanted gold stripes with painter's tape.

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qquake2k

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For some reason, the black paint wouldn't stick to the gold. So I primered over the gold, let it dry, then sprayed the black. Got much better results that way.

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qquake2k

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Several coats of black paint, and she's starting to look pretty good!

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qquake2k

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The gold paint really brought out the flaws in the nose cone. I should have spent some time filling the seams. Hindsight is 20/20.

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qquake2k

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Time to remove the tape. I approached this with some trepidation, because I don't have a very good track record with masking tape and paint. On rockets in the past, I've had a lot of problems with paint bleeding under the masking tape, and with the tape peeling paint off the rocket. But that was before painter's tape. I love this stuff! While not completely perfect, by far the best results I've ever gotten.

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qquake2k

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I know it's far from perfect, but I'm very pleased with how the Hijacker turned out. I love the gold accents and think they'll look good with the decal. This was a very easy and fun to build rocket, and I look forward to building more Mercury Engineering rockets.

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DM1975

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Looks like you got yourself a winner there. Looks very nice. LEt us know how it does in the air.
 

qquake2k

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Final step, applying the decal. It's a very nice looking peel 'n stick. I am a little concerned about how well it'll hold up, though. I haven't decided yet if I'm going to clear coat it, use Futura, or what. I've read a lot about rocketeers here using Futura, but am unsure exactly how it's used. Regardless, I'm looking forward to flying the Highjacker. Weather permitting, the first flights will be at the LUNAR launch next Saturday. I already have some F20's and a G80 ordered and on their way to me. I'm getting excited!

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DM1975

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Qquake2k, the sticker should hold up fine, just be sure to rub it on well. As for the Future floor wax, you can apply it with a foam brush, just straight out of the bottle, or you can air brush it on. It shouldn't need thinning, but if it does then I believe Isopropyl Alcohol should do the trick, but you have to clean that airbrush good with ammonia... I mean real good or you will ruin the air brush for good.
 

qquake2k

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I received the 1/8” braided tubular Kevlar today that I had ordered to use in the Highjacker. When I put the rocket together, I tied a long loop of string to the eyebolt, with the idea of using it to pull the Kevlar through it. I tied a loop in the end of the Kevlar, but couldn't pull the knot through the eyebolt. I retied the knot several times, but to no avail. So I finally tied the string onto the Kevlar, without tying a knot in the Kevlar. Worked like a charm. I just pulled the Kevlar through, and tied a knot in it, making a long loop.

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qquake2k

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Well, I finally got to launch the Hijacker yesterday at the LUNAR launch. The wind was atrocious, and I almost didn't launch it. My nephew Wes was with me, and he kept trying to talk me into it. I kept going back and forth, and finally decided to do it. The motor was an Aerotech F20-4W. I discovered that the stupid little rubber band won't hold the Copperhead ignitor in. I had to use masking tape. But it ignited the first time, and was a pretty good flight in spite of the wind.

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qquake2k

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It weathercocked into the wind quite a bit, but I didn't mind. I knew it was going to drift quite a ways on the 28" parachute. The orange cloud is chalkline chalk.

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