Estes Expedition Kit # 7249 Build Thread

[Howie]

Hey everyone, this is my first build thread I'm posting to this forum. Thank you to all who have posted in the past - you've been most helpful - and hope I measure up to their high standards here.

Here is a picture of the kit itself. As you can see, it's got a colorful scheme, and it has several transitions in construction, making this a Level 4 kit:



Before assembly, I primed the four external tubes of the kit: BT-55 upper body tube, the two BT-60 tubes that will become the three fairings around the lower body tube, and the BT-70 lower body tube.

Construction begins with the motor mount assembly. The motor mount tube is BT-50 24mm tubing. The motor mount clip is 3-3/4" long to fit an E12 motor, or C11 / D12 motors with the supplied orange engine block. The large simulated nozzle is a cone transition that is cut out from a printed pattern on a cardstock sheet. This attaches to a small centering ring at the top and a larger perforated centering ring at the bottom. This slips onto the motor mount tube and over the motor clip. The top of this nozzle butts up against the lowering centering ring for the body tube. Here's that completed assembly:



I'm not a fan of disposable wadding, so I took the center out center from one BT-50 / BT-70 centering ring and cut that into two half-moon pieces. After coating one side of each with quick set CA glue, I glued those inside the motor mount tube to create a S-baffle. I also deviated from the kit by attaching a kevlar cord to the motor mount as well. After attaching the centering rings at the forward end of the motor mount tube, the central centering ring and upper body tube attaches as shown:



To make sure the upper tube was properly aligned, I temporarily slipped on the centering ring that will go inside the top end of the lower body tube onto the end of the upper tube. After gluing the tube on, I rolled this assembly on a flat surface to make sure everything was straight before the glue set up.

 

[Nytrunner]

I've seen this kit on the shelves. It'll be nice to see how it goes together.

 

[Howie]

Next step is to mark lines on the lower body tube. Thoughtfully, Estes provides two complete sets of instructions, so one can cut out the alignment sleeve from the non-English instructions. Three lines running the length of the tube at 120 degree intervals set the spacing and alignment for the fins and fairings. Once this is done, the lower body tube and upper centering ring are attached.

Fin attachment is next. These butt to the lower body tube, and the fairings are slotted and attached over the fins, providing a through-the- wall mount.
Here's one fin attached:



The instructions include a cut out template for the fairings. This is used to mark the BT-60 tubes for cutting out the fairings. To ensure symmetry for the template, I folded it in half on the centerline, and cut both sides simultaneously with scissors. After tracing the templates onto the tubes, the fairings are cut out. I found out the best way to do that was to use scissors, and take a rough cut about 1/8" outside the final curve. Once the fairing is free of the tube, make a second cut carefully along the traced curve. Two fairings come from one body tube as they are staggered end for end. There's two body tubes so four fairings can be cut out of necessary, but only 3 are used. Here's two pictures showing an intact body tube and a cut out fairing. This is probably the most tricky part of the build.

 

[Howie]

I made a slight modification: if the fairings are cut out according to the instructions, the bottoms edges of them are not level with the body tube, but angle up slightly since the fairings mount at an angle. I cut mine slightly over length, and after taping them on with the bottom centerline of the fairing lined up even with the body tube, I trimmed the lower edge to line up. This resulted in the bottom of edges of the fairings and body tube all being in one plane. Not necessary and many will skip this, but I like the looks of this better.

Once the fairings are fully cut out, a crescent piece from the cardboard sheet is glued onto the base of them. Once these dried, I wrapped a sheet of cardboard around the lower body tube that these fairings attached to. I sanded the edges of the fairings back and forth to get eliminate any small misalignment from the cutting process and provide more bonding area, especially at the front. After cutting slots into the fairings for the fins to pass through, they are ready to glue on. The centerlines of the fairings match up with the alignment marks on the body tube at the front, and at the rear, the fin slots through the centerline align the rear of the fairings.

For gluing the fairings on, I used both wood glue and quick set super glue. I spread-ed wood glue around most of the edge of the fairing, leaving several gaps where I'd use the super glue. After setting and aligning the fairings, I used the super glue in spots to set them in place. This way I could take advantage of the quick set characteristics of the super glue, and the toughness of the wood glue. Here's how they look installed:

 

[Howie]

The main body construction concludes with a cone transition. This is cut out from pre printed cardstock, and formed. Once dry, it slides down the upper body tube to rest against the lower body tube. At this point I'll mention the fit of this and the nozzle cone was excellent, and the fairings were very good, only requiring slight filling. There are three cardboard strakes that glue onto this transition. One covers the seam, and the other two are at 120 degree intervals for aesthetics. Here's how they look installed:

 

[Overeasy123]

Wowie-Zowie, Howie! That's a Clean Build!

 

[Rex R]

for future reference, the term 'half-moon baffle' is a bit of a misnomer, they work better if the baffle plates cover about 2/3 of the tube instead of only 1/2 way.
Rex

 

[Howie]

The rest of the build is pretty straight forward. The nose cone comes from one of Estes' Honest John kits, judging by it's shape. There's grooves around it near the base that I chose to fill for aesthetic reasons. I substituted an elastic shock cord for the supplied rubber cord, and also a 15" nylon parachute for the plastic 18" parachute. I have more faith in the ability of a nylon chute to unfold when packed to allow an altimeter to fit on top of it, and well as cool weather flying reliability advantages. I used 1/4" launch lugs in place of the supplied 3/16" since I fly an number of other rockets off that size rod. The rocket received a coat of white Duplicolor primer in preparation for the color coats.

At this point I wanted to fly it, so I took it to the next launch I attended. I attached a Jolly Logic Altimeter 2 to the base of the nose cone to log performance data. With the parachute I selected there's little room to spare, but everything does fit without over packing.

My first flight was on a D12-5, yielding a straight boost and coast, peak altitude of 575', a deployment at about apogee, and a descent rate of 11MPH.

Next I installed a E12-6, giving the same qualities with an altitude of 865', and oddly, a slower descent rate of 9MPH.

Painting and decals are the next steps, after which point I'll have a completed weight. I weighted it in it's current state, but I don't have my notebook at this time.

Already I'm giving some thoughts to an upsized version, since there are several larger Honest John kits on the market. One I'm aware of is Madcow Rocketry's 2.6" kit, which would be approximately 2X scale. For a real challenge, Polecat Rocketry make a 5.5" version, roughly 4x scale. Someday I'll likely give this a try, but if someone else tries this first, I'd be eager to hear about it.

 

[Howie]

Thanks for the feedback Rex R; I'll remember that for similar future builds.

 

[ipostelnik]

This is definitely a cool kit to build. I've had one sitting on my desk with first coat of primer for over a month. I should probably fly it naked given how little usable painting weather we've had.

 

[billdz]

Howie, any update? I just got this kit and would love to hear more about your experiences with it. You didn't mention the clay that we are supposed to stuff into the nose cone, did you use it?

 

[Mugs914]

Thanks for posting your build Howie. I have often had my hand on that kit when visiting Hobby Lobby with a 40% discount coupon burning a hole in my pocket. I think I'll grab one next time. It looks like a really fun build!

 

[gldknght]

With the smaller parachute, have you had any damage to the paper tail cone from landing impacts? I'm just starting building mine.

 

[Greg Furtman]

Howie, I'm building one right now & so far, so good. There is an orange spacer, part W, that is mentioned no where in the assembly instructions. What's it for? To confuse people?

 

[billdz]

It goes into the motor mount if you are flying with a D motor. Not used when flying with an E motor, which is longer.

 

[Greg Furtman]

billdz, thanks for the info. Makes sense.

 

[billdz]

No prob, let us know how it flies. Store the spacer in a safe place, it's easy to lose.

 

[Scott_650]

You can always cut another spacer from an expended 24mm motor. I tend to keep a pile of every diameter used motors around in case I need a motor block, spacer, etc...

 

[kuririn]

Looking good, Howie. I'm following this with interest, since I have one waiting in the build pile.