Estes Executioner

[london_rocketman]

I am in the middle of building the Estes Executioner, which is a E rated rocket.

From the packaging it looks like a pretty decent kit. Then you unpack it, and see the typical Estes tubing than is thinner than a toilet roll.

The problem I am coming across with this kit is fitting the coupling to these pathetic tubes. Firstly, the Estes tubing buckles and cracks under the slightest of pressure from your hand, and secondly the coupling is SO tight that you are forced to apply a lot of pressure to get it in. I have sanded them dame thing down (and believe me that isn't much to sand in the first place). Even on the tubing, using a file I have slightly filed down the corner so the coupling can slide in better. But I know when I put some wood glue on, it is going to be struggle to fit this bugger in, and annoyance leads me to applying more hand pressure.

Has anyone else came across the same problem, and solution or workaround before I stick them together?

 

[jj94]

I've had problems like that before. What I do is sand it down a bit or, if it's thick enough, peel a very thin layer off of the outside. If I think it will be hard to glue it in because of the thickness and tackiness of the glue, I thin out the glue with a bit of water. That's not a bad thing either, because the thinned out glue will soak into the paper even easier and provide an even stronger bond.

 

[powderburner]

Are you familiar with the word "burnish" or the physical operation that word represents?

When you burnish something like cardboard, you use a smooth metal tool to rub firmly on the edge or lip to compress the fibers. The cardboard must be WELL supported on its backside or you will simply crush the tube, so you might have some luck using a firm tabletop or similar surface and pressing the cardboard under your metal tool, against that work surface (you do this with the metal tool on the inside of the tube, sandwiching the cardboard edge between the tool and the work surface). You do this with the cardboard dry; no glue added yet.

I would suggest that you burnish both edges of the coupler, and then gently roll the coupler (while tilted) on a table to push the lip inward. It doesn't take much. Bending in just a sliver of the ends (1 or 2 mm wide) just a tiny amount (0.5 mm should be plenty) is enough.

Do the same thing to burnish the joining end of the BT. If you can gently "bell" the end of the BT outward your fit will improve greatly. Again, it doesn't take very much at all to open the edge of the BT by maybe 0.5 mm at most. (Later, during assembly and gluing, you can again burnish the edge of the BT back down into alignment while the glue is still wet, or you can let everything dry and do a little sanding.)

When it comes to assembly with glue (assuming you now have a satisfactory dry fit), coat the outside of the coupler with a thin layer of water-based glue. Coat the inside of the BT with a thin layer of water-based glue. Let the clue dry completely. Slide the pieces together, into place in their final configuration, and swab a few drops of water onto the joint; they should "wick" into the crack and you can follow with more drops of water. The water will re-activate the glue and you will not be able to move or adjust position of the parts, so get them properly fitted while dry.

As to sanding the inside of the BT or the outside of the coupler, I agree with you that they are thin enough already. I would be a bit nervous about removing much of that structural material. Besides, once it is finally together, you WANT it to be a tight fit, right?

Hope that helps-

 

[MarkII]

I have just started to build an Executioner, too, and I absolutely agree with powderburner's advice. Estes parts generally fit together very well, with little or no play. As he described, you may need to burnish down the cut ends of the tubes and the coupler, though; when they are cut, a small burr forms around the lip. All tubes develop a burr around the cut edge like that, not just the ones that are in Estes kits. Estes BT-80 has a wall thickness of 0.021" (0.5334 mm). This is the same thickness used for all of their tubes from BT-55 through BT-101. BT-80 seems to be "soft" because of the large inner diameter, not due to the walls being too thin and flimsy. (Deprived of its internal structure, the walls of the first stage of the Saturn V could be easily creased, too, for the same reason.) If you really want to, you can get heavy-walled versions of the same tube from Semroc, BMS and other sources. The OD of that tubing will be greater, though, so your nose cone/tube junction will have a "step" to it, unless you get a version of that same nose cone that is sized for the heavier-walled tube (from the same sources as the heavy tubing).

The rocket will be noticeably heavier in weight, too. Using the standard-walled BT-80 is what makes it possible to launch the Executioner on an Estes E9. If you change to the heavy-walled BT-80, you will need to use at least an Aerotech E15 in it. (You can also use high-thrust D engines, too.) Remember that once the motor mount, the fins and the coupler are installed and glued in, the Executioner's airframe will be much more solid. A friend of mine launches his unmodified Executioner on F's with no problems.

When you go to bond the coupler into the body tubes, use a somewhat thick bead of Elmer's Glue-All inside the tube. Elmer's doesn't dry so fast, and the thick bead means that it will dry even slower. While it is wet (and thick) the glue will actually act as a lubricant to help you slide the coupler in. Don't slop a really thick bead in, though, because it will wrinkle and weaken the paper. And don't take your time about sliding the coupler in, either, because even with this method, it will grab tight within a few seconds.

One thing that you will need to watch out for, though, is the fit of the fins in the lower BT's slots. The Executioner's fins are 3/16" thick, but on my kit, the slots were only 1/8" wide. I measured and cut the tube (on the same side of the slot on all three slots) to widen them so that the fin tabs would fit through. When you widen the slots, make sure that you cut away material on the same side (such as on the left side) of each slot in order to maintain the correct spacing for the fins.

MarkII

 

[london_rocketman]

Unfortunately it is too late for this kit. I had problems from the start.

I originally ordered the kit back last Christmas. When it arrived, the tubing had been buckled slightly in the post. After a long argument with the shop keeper, I got replacement tubes, without the lasercut the fin holes. Not a problem, as I cut the holes out myself.

The first part of the coupler I successfully stuck in to the correct depth of the lower tube. I prepared the second tube, and testing revealed it was tight, but could slip in place. However with the thickness of the glue, I managed to get the tube in 90% of the depth. At this point the kit required too much force even onto a flat surface to push it anymore, as too much force was going to buckle the tube.

Not the biggest disaster, as I can use this small 8mm gap as a painted band.

However thanks for the advice. Much of which I had already applied in some fashion. But the lesson I have learned is that I am staying away from Estes kits now, as the slightly delicate parts frustrate me when they go wrong. :bangpan:

When I can find the camera, I will take a shot for you. Have a good laugh. :roll:

 

[BAR0051]

I have flown my bashed Estes Executioner on 3 F39 motors (94% G, almost an H). The only mod, other than the motor mounts and slightly oversized fins, was gluing on the nose cone and splitting it in the middle where the coupler had been made into a baffle. With proper construction, cardboard tubing will take more than most would think. I have flown a cardboard mailing tube scratch built rocket well over the speed of sound, though it was a much thicker cardbord than Estes.

 

[RimfireJim]

You can have coupler insertion problems with glue almost regardless of the fit of the coupler, and it's not due to the thickness of the glue, it's due to the paper-based products swelling as they absorb the moisture from the glue. The trick is to use slow-tack glue like Elmers Glue-All (PVA) and WORK FAST. With all the bond area, it takes only a thin film of glue to get a strong joint.

If I encountered a coupler that was too tight, I wouldn't sand it or the body tubes - I'd cut a narrow slit out of it lengthwise so it could close down to fit in the BT.

 

[fxrs]

I built an Executioner last year. When I removed All of the parts
to inspect before any work started I found all of the fins warped
beyond use. I called estes and they said they would send me new
fins. I was anxious to get started so after a few days of waiting
I went to the hobby shop and bought some 1/8" thick 5 ply
plywood and made my own fins. Eveything else in the kit was
in good shape. I had no trouble with the coupling. I made mine a
two motor cluster and I used 2 part epoxy for all of the assembly.
As far as the gap between the body tubes, I leave about a 1/16"
or 1.5mm gap and smooth the epoxy over into the gap. I can sand
that smooth and you can't see where the two tubes come together.
The first picture of the launch lug is also were the tubes come together.
the joint is the black ring around tube. The 2nd picture is of the cluster
mount with slots to hold the through the wall fins and there is a
picture of the finished rocket.