Estes Shark #1111, Build, Part 8, Engine Mount & Fin Gluing

Set the engine mount and Kevlar line alongside the lower, longer tube.

The BT-20 engine tube is even with the bottom of the BT-50 main body.

This gives you an idea how long the Kevlar line should be, a little shorter than the top of the BT-50.

Tie a overhand loop knot (shown on the right) for the elastic shock cord attachment.

I used epoxy to glue the mount in, allowing me some positioning time.

Here's the BT-50 tube with the filler/primer scraped off where the fins will be glued. The scraping is a little shorter than the length of the leading edge.

The low fins are glued even with the end of the body tube.

On the forward fins and thrusters, I used a wrap of masking tape as an low alignment line at the corner of the trailing edges.

Estes Shark #1111, Build, Part 3, Engine Mount

The 20/50 rings were notched for the engine hook and Kevlar line.

The lower ring is on the left. I highlighted the notch with pencil.

The upper ring is on the right. Note the Kevlar notch directly opposite the engine hook  notch.

The instructions would have you position the upper ring above the top bend of the engine hook. I position the upper ring lower, over the top of the hook end making a stronger mount.

The Kevlar line is set directly opposite the engine hook.

The loose end of the Kevlar line is pressed into the upper ring glue fillet.

1/16" diameter heat shrink tubing is slid down the Kevlar and rests against the top of the ring.

Hit the heat shrink tube with a heat gun, shrinking it around the Kevlar.

Estes Time Warp Build, #7321, Part 5, Upper Centering Ring

Here's the upper laminated centering ring,

glued 1/2" from the bottom of the BT-5 tube cluster.

The instructions say to add glue fillets down and between the three tubes.

TIP: I wouldn't do this, it's a long, deep joint. When the glue dries you'll have bubbles and an uneven fillet.

I used a few drops of glue to fill the small center gap. This will block any ejection charge escape.

Years back we used "tissue/glue putty" to fill gaps like this. Tissue/glue putty is a mix of glue and tissue torn into very small pieces. It makes a strong gap filler.

This gap is small, if it were larger I'd make up some tissue/glue putty.

To read more about this gap filler: CLICK HERE 

This top and bottom glue fill also strengthens the mount.

Estes Time Warp Build, #7321, Part 4, Centering Ring Laminates

The center triangle of the centering rings will probably break off. There's not much to hold it in the center.

I'll show how to block the hole (and the ejection charge) in the next post.

When laminating the two sets of two rings, 

use one of the BT-5 tubes to check the alignment.

Don't glue the tube to the rings (yet), use the tube to be sure all three holes are lined up.

The instructions suggest sliding the ring down from the top into a glue ring.

For a cleaner build and less visible glue -  

I slid the centering ring up from the bottom pushing the glue ring up. It's a cleaner visual outside joint on the finished model.. 

You don't have to use much glue, you can always add a glue fillet later.

Estes Time Warp Build, #7321, Part 3, Engine Blocks

Jim Flis (Fliskits) gets credit for this engine block setting idea calling it the "Block and Tackle.".

TIP: The mini motors (friction fitted) extend 1/4" out the rear of the BT-5 tubes. 

A 1/4" strip of masking tape is wrapped around and even with the end of the yellow spacer tube. 

This tape ring stops when it hits the end of the tube. 

All three engine block will be at the same depth.

The instructions the engine block glue line at 1" inside the tubes.

I'd recommend using a dowel pencil marked at 1 1/4" to apply a ring of glue inside the tube.

Apply the glue ring, slide in the engine block. Use the taped yellow tube to set the ring depth.

The three BT-5 tubes are ready for the centering rings.

Estes Time Warp Build, #7321, Part 2, Paint Plan & Engine Tubes Fill

Planning ahead!

If you want to paint the rocket in the face card colors, paint the build in sections before gluing it all together.

The BT-5 cluster tubes are yellow and would be difficult to paint if glued into the gray BT-55 tube.

That yellow adapter could be painted before gluing into the white BT-50. Same goes for the gray nose cone. Paint them before gluing together and get instant "masks" or color separations. 

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The lower centering ring is glued 2" down from the tops of the BT-5 motor tubes. I filled the tube seams below that.

The seams were shallow, here you can see the pencil lines where they could be felt.

CWF was used to fill the bulk of the seams and sanded smooth.

The upper 2" (glue area) was masked off and the low end sprayed with filler/primer. Sanding this down filled any remaining seams.

Estes Semi-Scale Saturn V, Kit #K-39, Part 3, Engine Mount

Cutting the coupler a little oversize allows you to sand to fit.

On the left, one side of the coupler cut size is sanded on a block with 220 grit.

On the right, clear tape holds the ends together with a good, slip fit.

Here's the finished engine mount. 

The clear coupler is held in place between the upper two centering rings. There is no glue holding the clear coupler to the rings.

The kit didn't include and engine block, I added one.

Before cutting the fin slots, the tube seams were filled. 

These older tubes had very tight, almost invisible seams. It only took one good shot of filler/primer and sanding to fill them.

On the left, a paper towel is wrapped around a painting wand for a better fit inside the BT-60. On the right, an inside wrap of tape keeps out the filler/primer spray.

Estes Semi-Scale Saturn V, Kit #K-39, Part 2, Engine Mount

About 3/16" of the inside of the motor mount tube got a wipe of CA glue applied with a Q-tip.

Never apply CA glue where a wood glue joint will go later. Wood glue needs to soak into the surface. CA glue seals the area where it is applied.

The instructions say to cut a 1/8" square notch in a centering ring.

I used my rotary punch to cut a half circle for engine hook movement relief.

The upper ring got a slight recess cut for a better fit over the engine hook.

Instead of cutting out a 1/8" slice from the clear oversize coupler, cut a single line. Use an aluminum angle (set inside) for a straight cut line.

Slide the coupler in the BT-60 and check the overlap. Mine was a little less than 1/8" wide. Mark and cut the second line a little oversize. Final fitting in the next post.

GOTCHA: When testing the fit of the clear coupler, I found it was cut uneven. One side was longer than the other by about 1/16". If used as supplied, the third upper ring would sit at an angle when butted up against the coupler top. The long side was sanded so all sides were the same length.

Estes Monarch Build, #7214, Part 3, Engine Mount

The finger tab was cut off and the engine hook flipped over.

A subtle curve was bent down the length of the hook for better motor retention.

The upper centering ring got a small punch for the added Kevlar line.

The upper ring was slid on just over the upper bend of the hook for strength. 

The rest of the mount was assembled as shown in the instructions.

A 1/16" diameter heat shrink tube was slid down the Kevlar line and against the top of the upper centering ring.

Thanks go to Rick Randoll of NewWay Space Models for this Kevlar heat protection idea. 

A heat gun on low setting shrinks the tube around the Kevlar line.

The inset picture shows the Kevlar line below the base of the lower ring, set into the glue fillet.

Estes USS Enterprise #1275, Part 20, Engine Mount

The engine mount assembly is pretty standard.

The kit didn't include an engine block. I installed one using a Q-tip to apply a glue ring from the top. The block was slid in until it rested in the glue, against the upper bend of the hook.

The "recovery probe" assembly is held by a second engine hook that clips into a slit in the engine mount tube. A slit is made at the bottom of the glued in coupler.

This upper hook is not glued in. I'm checking the slit and position of the hook.

Here's the finished mount.

A bead of glue was applied to the upper bend slit of the tube.

New Way Blade Runner, Part 7, Gluing In The Engine Mount

The Kevlar and shrink wrap are run down thru the mount so they won't get in the way.

The instructions have you apply glue 1 3/4" from the bottom of the main airframe tube.

I use a dowel to roll a line of glue inside the tube. Setting the dowel beside the engine mount shows me the glue line would be better at 1 7/8" to apply the glue just below the upper centering ring.

Notice the two depth pencil lines on the dowel. The lower pencil line is the 1 7/8" mark.

A ring of glue is set around the top edge of the dowel.

Set the dowel in the tube up to the 1 7/8" pencil mark and roll the glue into a ring line inside the tube. You will have to apply more glue on the dowel to get a ring all the way around inside the tube.

Slide the engine mount in, turning the mount when in contact with the glue to even out and make a smooth interior fillet.

With the mount glue dried, 

TIP: Note the straightened coat hanger hook in the right side picture. The hook will help get the shock cord back through the top of the tube.

 

There isn't much room to get a fillet at the lower centering ring/body tube joint. 

I applied a small glue drop to one side of my long tweezers. Set the drop in on the joint to smooth as best your can. Keep some Q-tips handy to pick up any glue boogers.

New Way Blade Runner, Part 6, Tying Elastic Shock Cord To The Kevlar

As I normally do, some steps are out of order from the instructions.

I like to mark the body tube seams with a fine point pencil for visibility when filling.

The tip of my knife blade is dipped in thinned CWF. Wipe off the back of the blade leaving the filler on the top side of the knife. Set the knife in the recess seam and with a back and forth motion of the knife, leave filler in the seam.

You should be able to leave filler for a length of about 1 1/2". If not, your filler needs more thinning with water.

The instructions spell out how to tie the elastic shock cord to the Kevlar before gluing the engine mount in. You don't want the Kevlar line to extend beyond the top end of the body tube. This can lead to a "zipper" at an early or too late ejection, the Kevlar tearing through the body tube. 

Set the mount along the side of the body tube with the 1/4" pencil mark on the mount even with the end of the tube.

Straighten the Kevlar line out down the tube to the top. Mark the Kevlar 2" down from the top of the tube.

At the 2" mark, tie the Kevlar to the elastic shock cord using a simple, overhand knot.

The short, larger diameter heat shrink tube is slid over the knot. 

Hit with a heat gun or hair dryer at the low setting. On the left is the before, on the right is after using heat.

You can cut off the excess.

New Way Blade Runner, Part 3, Engine Mount

The rings are glued in place on their 1/2" marks made earlier.

Tie the Kevlar with a small square knot. Cut the loose tail off at about 1/2" long.

Press the Kevlar loop, knot and tail into the glue fillet.

Slide the heat shrink tube down the Kevlar line until the end rests on the upper centering ring. 

While holding the heat shrink tube against the upper ring - 

Apply heat using a hair dryer or heat gun on the low setting. It should shrink around and tighten over the Kevlar.

When tying the Kevlar knot, make it small and tight against the motor mount tube. There isn't much space between the BT-20 and BT-50 tubing.

Notice the Kevlar relief notch is to the outside edge of the upper ring. This keeps the Kevlar to the outside of the hot ejection charge.

Estes LTV Scout, Build, Part 11, Engine Mount Gluing

I used a dowel to roll a line of glue inside the body tube. The upper ring would slide into the glue ring.

The mount is held beside the body tube alongside the dowel. The top of the dowel is just under the upper centering ring.

At the bottom, the dowel is marked with pencil for a depth guide.

Note the masking tape around the engine mount. The tape is only there for a pencil mark at 1 9/16" from the end of the tube. The low end of the tube will extend 1 9/16" out the back.

Apply a line of glue around the top of the dowel.

Roll the glue ring inside the tube using the pencil line on the dowel for the correct depth.

Slide in the mount. when you reach the pencil depth mark, turn the mount to spread and even the glue at the upper centering ring.

The lower ring fillet was applied using single drops of wood glue applied with a Q-tip. Enlarge the picture to see the glue fillet.

The low conduit section and base cap are glued together using Fabri-Tac. Notice the alignment "key" notches before gluing.

Apply more Fabri-Tac to the inside of the tube and the low end of the motor tube. Slide in the low conduit assembly rotating the engine hook relief notch around the engine hook.

Estes LTV Scout, Build, Part 4, Engine Mount Gussets

These are probably the thinnest centering rings I've ever run across - The thickness of two layers of 110 lb. cardstock. I've used gussets in the past to beef up an engine mount.

   

I wanted the gussets at a 120 degree spacing or close to it.

A copy paper strip was rolled around the BT-20 tube. Two even folds were made giving three gusset positions.

Wrap around the tube and mark at the folds and where the strip meets.

This is why I save excess balsa left over from other kits.

3/32" thick balsa strips were cut to fit between the two centering rings. These were made a little wide to be sanded even with the outside ring edge after the glue dries.

Here's the final, finished engine mount. 

It's always surprising how much stronger gussets make the mount feel.

This shouldn't be considered "bulletproofing" a LPR model. Just some lightweight strengthening.

Estes LTV Scout, Build, Part 3, Engine Mount

The engine block was installed just above the engine hook slot position using a glue ended dowel.

The engine hook had a slight reverse bend in it.

I bent a gentle curve to better retain the motor.

The instructions mentioned a hold down strap on the pattern sheet (back of face card). There wasn't one.

No big deal. I used a wrap of electrical tape which would last longer than masking tape.

A drop of wood glue was set over the upper bend of the hook.

The finished mount. Those rings are thin!

The upper ring is set down about 1/8" to allow a glue fillet on both sides.

Estes LTV Scout, Build, Part 2, Engine Mount

The low inside end of the engine mount tube got a swipe of CA glue. The edge also got a wipe of glue.

Sand the glued end square with 400 grit.

This end will be exposed, it is not a glued surface. The CA glue seals and hardens the tube end.

 

The engine hook slot cut is made in two steps.

Note the blade is flipped over making two small joining cuts.

Stab and make about half the cut.

Turn the blade over and complete the cut from the other side.

The two facing cuts give you a slot with squared ends - less chance of a tear.

For whatever reason, Estes didn't include an engine block in this kit. I added one.