Aerotech Mega Initiator #89541, Part 9, Assembling The Engine Mount Adapters

In the last post, I did some dry fits until the rings were tight on the tube, but still moveable.

Here I'm using the flat face of my sanding block to get the lower ring flush and square with the end of the motor mount tube.

Here's the engine mount ready with the upper ring 1" from the top of the tube.

A dry fit ready for the epoxy fillets.

Epoxy fillets were applied with a gloved finger and smoothed with alcohol.

In the picture, I've applied a fillet and am removing most of it with a Q-tip. This is the ring that "sockets" into the larger engine mount tube. You don't want excess glue to hinder the fit.

 

The finished adapter.

The other two mount assemble and glue up the same.

Estes Black Star Voyager Build, Part 29, Filling The Fin Halves Joint

The joint got a coat of CWF and sanding.

Notice you can't see the U support piece, it's hidden inside the joint.

I wrapped a paper towel around the vanes previously painted with the metallic black.

I carefully sprayed some filler primer only on the joint.

After that dried, it was sanded with 400 grit on a block.

I was concerned about any misalignment of the joint but after sanding, the fit was good.

A glue fillet was applied to lock the U brace piece in place.

Estes Star Stryker Build, #3206, Part 7, Lower Fin Gluing

The first lower fin glued in place.

Four more to go - 

On the left is how much glue I use on a root edge, right out of the bottle.

On the right is how much glue is used to tack the fin in place. Run your finger down the sides of the root edge picking up and removing excess.

Using less glue means very little squeeze out outside the body tube joint.

Viewed from the rear: 

At the 12 o'clock position you can make out the rear fin in line with the larger forward fins.

All ten fins and the launch lug and standoff in place.

This is a very busy tail end.

Estes Star Stryker Build, #3206, Part 6, Upper Fin Gluing

Here's the first of the upper five fins. 

On the left, notice the wrap of masking tape for positioning the high end tip of the leading edge.

The picture at the right shows the trailing edge on the pencil fin line.

All five upper fins in place. 

That tape wrap above keeps all the fin root edge tips in line.

I went ahead and started glue fillets before gluing on the lower, smaller fins.

I like to start applying glue fillets on the root edge body tube joint - at the top and bottom before filleting the longer sides.

This shows how much glue I use when making fillets.

On the left is the the wood glue right out of the bottle, drawn down the root edge of the fin.

On the right is the glue smoothed out with the tip on my little finger.

Airflow Video Using Computer Modeling

From the NASA Aeronautics Facebook page:

A fascinating video showing airflow around wing and the jet engine.

Reminds us how smooth glue fillets can improve airflow at the fin/body tube, trailing fin edges and launch lug joints. 

Along with international partners, we're using the same generically shaped wing design to create research models that will help us better understand how air moves around an aircraft during takeoff and landing.

Learn more about how we’re using computer modeling and wind tunnel tests to ensure the aerospace community gets accurate answers: https://go.nasa.gov/3zaI682

To watch the video, CLICK HERE

Estes Skytracer Clone #1361 Build, Part 13, Mask & White Paint

I masked off the glue line for the thruster assemblies. Look close and you can see the thin masking tape line.

The model is ready for the first white coats. In the front end a rolled up paper towel keeps paint out of the tube.

Easy paint - most of the model is an overall gloss white. The small nose cones in the thruster units aren't glued in yet, they will be painted black separately off the model.

Enlarge the picture and you can see some ridges down the fillets.

The glue fillet ridges can be lightly sanded with some 400 grit.  Don't sand into or dip into the balsa! Just knock off the high glue spots.

 

In the picture you can see the paint and fillet have been dulled with the sandpaper.

NewWay Angled Invader, Part 12, Gluing On The Wing Pods

TIP: I have started sanding the fillets before painting the rocket.

Hold the glued area up to a light and you can see the rough areas in the shiny dried glue. These will be seen after the spray paint is applied.

I lightly sand the rough fillets with a piece of 800 grit. Why 800 grit? 400 grit sandpaper can add scratches that will be seen after painting.

On the left is the before, on the right after sanding. (I know it's not the same fillet area, but it does represent what I'm talking about.)

Sand enough to just remove the shine. Your fillets will be smoother when the gloss white undercoats are sprayed.

The pod gluing area needs to be scraped then sanded where the glue joint will be.

Set the pod slot next to the outside wing tab and mark with pencil.

On the right, area between the pencil marks has first been scraped with an old knife blade then sanded with 400.

The picture doesn't show it well, but the gray primer has been taken down to the brown tube for a stronger bond.

Here's the pod in place before fillets.

I don't use a lot of glue for the initial placement. Less glue lets you do small adjustments after it dries. The reinforcement comes with regular glue fillets after everything is in line.

Okay - 

Ready for white undercoats! 

Note the inside of the pods were already brush painted a phosphorescent orange.

NewWay Angled Invader, Part 8, Gluing On The Pod Fins & Launch Lugs

I don't use a lot of glue when initially setting on the fins.

Apply a glue line down the root edge, shown on the left.

Run a fingertip down the side edges of the fin leaving a line of glue in the center.

Wipe off your finger and repeat the finger line down the other side.

This refines the glue to the center and evens out the glue line.

Now I can set the fin on the body tube.

Using less glue makes for less "squeeze-out" along the sides of the root edge. After the glue has dried, less initial glue will allow for small readjustments. If you had used too much glue, that misaligned fin could be stuck for good!

After you are satisfied with the fin position, THEN add fillets for more strength.

The Fin Guide "A" is used again to hold the fins at an angle as the glue dries.

The squared dowel is glued onto the pencil lines drawn earlier.

The two launch lugs are glued on the underside of the main body 5" from the low edge of the tube.

Even though I had drawn pencil alignment lines, 

I could still slide the lug guide down the two lugs to check the spacing.

New Way N-21 Sky Fighter Build, Part 8, Filler & Glue Fillets

I did get a good fit of the wing edges at the top.

I still brushed on a line of CWF to fill any gaps.

This was sanded with 400 grit on a block.

At the front and rear of the wing center joints I did use some CWF applied with a knife blade.

This was carefully sanded.

There's a bubble in the left side fillet needing one more pass of wood glue.

I didn't do glue fillets all the way around.

On these square tubes, they are very slightly bowed out on the flat sides.

Making smooth, bubble free fillet would take many passes of wood glue.

Here's the fillets on the rear top.

I didn't do glue fillets on the underside of the wings.  

The gaps were pretty wide. 

Even using Titebond Quick and Thick this would be a tough fillet to lay and smooth without bubbles.

Estes Blue Origin New Shepard Build, Part 8, Tunnel Top Fillets

Glue fillets were applied using a Q-Tip.

Force the glue into the cracks. Pick up as much of the excess glue as you can. 

You'll want these inside surfaces smooth.

Here's a closeup.

I'd recommend using white glue. 

White glue will dry clear.

After the fillets,

I masked off the upper (pre-painted) nose cone and the shoulder below the tunnel tops and recess ring.

I needed to spray paint the tunnel tops and whiten the yellow glue fillets.

The paint was sprayed and showed there was still some fillet bubble gaps.

This time less glue was directed into the holes with a toothpick tip.

Again, use a Q-Tip to remove excess glue. 

After the glue dried, another mask and gloss white spray painting followed again.

ASP Micro Sandia Sandhawk Build, Part 7, Fin Fillets & Streamer Attachment

The CA glue fillets were lightly sanded smooth with 400 grit before spray painting an overall gloss white.

This shows how small the model is, just under 7" tall.

After the first gloss white paint coat dried, I ran the backside of my blade down the fillets to feel for any dips.

One fillet did have some divots. Another CA fillet followed with light sanding.
 

The Mylar streamer is taped to the Kevlar line.

Scotch tape was set down, wider than the width of the streamer. 

After pressing in place, the overhanging tape was  trimmed off without cutting into the Kevlar. 

New Way, Der Squared Max Build, Part 7, Fins Gluing & Fillets

Here's the square tube in the fin alignment jig.

The third fin slot is facing down, the side with no slot is facing up.

You glue the angled "side" fins using the jig.

The inset picture shows the glue application.

When the fins are slid into the slots, you'll have some glue squeeze out along the joint. I removed the assembly from the jig to pick up the excess glue with a Q-tip. Best to remove the excess now than try to smooth out dried glue later.

Set the fin/body tube assembly back in the jig to allow the glue to dry.

I applied glue fillets (on one side of the fin joint) while the assembly was still in the jig. After that dried, the body with two fins was removed and a glue fillet was applied to the other sides.

Many builders don't continue the glue fillet/fill under the ends of the fins at the trailing edge joint.

Left - Glue applied,

Right - Excess glue removed.

The same end fill can be done at the front and back edge joint of launch lugs.

New Way Mars Snooper II, Build, Part 16, Red Paint and Landing Gear Gluing

Don't glue in the nacelle nose cones yet!

Check out the third picture below

I usually pull the nose cones and adapters out of the tubes about 1/16". This allows paint to get into the shoulder a bit and insures coverage if the nose cone isn't slid all the way in.

This is a tough model to spray evenly. Notice the right side of the pod root edge. Spray the inside recessed areas first then shoot the model overall. 

A piece of paper towel was rolled up and slipped into the open end of the pod. 

This kept paint out for a better glue joint of the landing gear centering rings.

No need to glue the pod nose cone in place yet.

The picture on the left shows the model turned upside down. 

With the landing gear centering ring spaced 1/8" from the bottom of the tube, the top ring (right picture) ends up close enough to the top for an easy glue fillet using a Q-tip.

A glue fillet is applied with a Q-tip around the lower ring joint.

After the inside top ring gets a glue fillet, the nose cone is glued in using Beacon Fabri-Tac.

New Way Mars Snooper II, Build, Part 11, Vane Gluing & A Larger Tri-Fold Mount

The glue tends to bead up when applied to the edge of the vanes.

The picture on the right is after a fingertip was run down the sides of the fins. There is now a smooth, even glue bead.

TIPS: Apply the vanes in this order - 1, 3, 5, 7. Then fill in the spaces with vanes 2, 4, 6, 8.

This allows you to make fine spacing adjustments by centering the even number vanes between the odd number facing vanes.  

Fillets were applied to the root edges of the vanes.

It would be hard to reach under the upper shroud and smooth with sandpaper after the fins were glued on. 

I  gave the lower vanes a shot of gloss white.

Sanding followed with 400 grit.

The tri-fold mount seemed small.

I re-drew a new mount on some 65 lb. scrap card stock.