Estes Advanced Target Drone, Kit #1913, Build, Part 5, Engine Mount Gluing & Filler Primer

The engine mount is glued into the main airframe tube.

The end of the mount is even with the end of the BT-50 tube.

I used the flat face of my sanding block to push in the mount.

The fins grain and body tube seams got the usual CWF coat and sanding. 

Just the leading edge of the four fins was rounded.

The fins and launch lug were sprayed with filler/primer.

After it dried, the fins were flipped over and the other side sprayed. 

The nose cone and body tube were also sprayed with filler/primer.

The yellow Apogee nose cones do need some undercoats so the yellow tint won't show through the final color.

New Kit? Robot!

Had some inspiration last night - 

I've been playing around with this idea for a while. 

This is the first build of the ROBOT.

I wanted it to reflect the wind-up tin robot toys from the 1950s and 60s.

18mm powered, much like the Odd'l Rockets Little Green Man and Pigasus.

It is different with a rear eject of a 12" parachute.

The robot arms are bent to the front on the left, and turned back on the right side. This should give it some spin stabilization. 

Note I wrote "should".

The fins are based on a "track" for movement much like the Robot from Lost In Space. I borrowed the idea of the multi-fin design from the pre-production art of the Estes R2D2: CLICK HERE

In initial sketches, I couldn't get the head right! That was until I remembered Rosie the Robot maid from the Jetson's. The side set body tube works well.

New designs go through many changes before production, no balsa filling or color for now. I've learned not to spend a lot of time finishing a test model. Will it be a kit? 

Now comes the flight testing.

Estes Advanced Target Drone, Kit #1913, Build, Part 4, Engine Mount

The 20/50 rings were rough. I sanded the flat sides with some 400 grit on a block.

On the right - a 1/8" notch was cut for the engine hook relief. 

On the other side of the engine hook notch, a smaller notch was cut for the Kevlar line.

Notice the Kevlar line under the top bend of the engine hook.

The upper centering ring also goes over the top bend and the engine hook slit. This locks and strengthens the engine mount.

Tie a small square knot. There isn't much room between the BT-20 and BT-50 tubes. Keep the knot small.

On the right, I've tucked the loose end under the looped Kevlar line into the glue fillet.

A engine block is glued into the top of the mount against the upper bend of the engine hook.

Estes Advanced Target Drone, Kit #1913, Build, Part 3, Figuring Out The Decals

The original kit decals had a lot of white area.

To check the fit of the online scan, I set a white decal outline on the traced wing pattern.

This was copied and drawn with the other sized decals.

I haven't decided yet whether to print decals on a white decal sheet or:

Spray a clear decal sheet with white paint and cut out the pieces. 

Thee is AIR FORCE, blue numbers and the stars and bas that will be place over the white paint decals.

I'll probably use the white paint decals. Red paint (underneath) would will show through the thin white decal sheet. The white will look pink!

The stars and bars white areas (far left) were simplified in a second drawn version.

Estes Advanced Target Drone, Kit #1913, Build, Part 2, Redrawing The Cardstock Intake

 

Here's the scan of the intakes from the Jim Z's website:

CLICK HERE

I appreciate the patterns, but sometimes the scans are a bit rough.

Good thing the ruler is on the scan!

I dropped the art into Corel Draw and drew a 1" square box.

The art was sized so the 1" square box matched the 1" measure on the ruler.

Notice how the intake pattern and the ruler aren't on the same baseline.

Drop down a horizontal alignment line. Double click the intake scan and you can rotate it.

Start drawing the outside cut lines and the inside fold lines.

To be sure the long top and bottom trapezoid shapes are the same size, I drew a box that aligned with the top half.

Copy and slide down the copied box to check the lower half height. 

The slot was drawn with a thin solid line,

The folds got a dashed line.

Great thing about computer graphics,

Copy the original, paste and drop down an exact copy.

Estes Advanced Target Drone, Kit #1913, Build, Part 1, Parts

This will be a spare parts build.

Clockwise from left to right:

BT-50H (Heavy wall tube) 11" long

Apogee PNC-24C (a bit shorter than the original kit nose cone)

Odd'l Rockets 12" chute 

Some leftover Air Force decals I might be able to use

1/4 oz. Clay nose cone weight

3/32" Balsa sheet

1/8" dia. Launch Lug 2 3/8" long

20/50 Engine Mount

Round elastic shock cord

135 lb. Kevlar

More about the cardstock in an upcoming post.

Estes Advanced Target Drone, Kit #1913, Clone Build Background

The epoxy fillets on the Mega Initiator will take some time, I'll get back to that build soon -

Introduced in the 1983 catalog is the ADVANCED TARGET DRONE.

Kit # 1913, available from 1983 through 1985. Original cost was $6.00.

Information from Jerry Fortin's database: CLICK HERE

This is a four fin, nose cone model but has cardstock intakes that slot over the longer "wing" fins.

15.3" tall, 1.3 oz weight, BT-50 based with 18mm power. 12" parachute recovery.

The interesting part will be making the white decaled areas at home.

The build starts tomorrow!

Builds On Display!

While the epoxy dries on the Mega Initiators -

Around a year and a half back, I donated ten display builds to Colonial Hobby in Orlando, Florida.

I checked back last December and the models were still in a cardboard box, sitting on top of a file cabinet.

I let them know if they weren't going to display the builds, I'd rather have them back. They took the hint and finally put them on display!

Most all these are my builds, from left to right - 

The Andromeda, Long Tom, Sprint XL, Alien Invader, Laser Lance, Scram Jet, Bullpup, Goblin, QCC Explorer, Little Honest John. I don't know who built the others.

They did honor my one request - keep them out of reach! They are up on a shelf at the back of the store, to the right of the rocket kits.

Aerotech Mega Initiator #89541, Part 11, Gluing In The Engine Mount

Test fit, test fit, test fit -  before gluing on the centering rings.

The mount is slid into the airframe tube and the fin tabs slipped into the fin slots into the centering ring notches.

Here I've marked the position of the bottom edge of the ring with masking tape.

This allows me to apply the epoxy to the upper side of the ring. After that dries, the tape is pulled and an epoxy fillet is applied to the underside joint. Repeat the epoxy fillets on the other centering rings.

You are given the choice of gluing in the mount then attaching the fins or - 

Extend and cut the fin slots down through the bottom of the body tube. The fins are glued onto the mount then the entire assembly is slid into the tube thru the extended fin slots.

I decided to not extend the fin slots. Sometimes this extended cut allows the tube end to flare out.

Before you use epoxy - 

Some people are allegic to epoxy. Use a gloved finger to smooth out epoxy fillets.

With the fins dry fitted in their slots, 

this puts the low centering ring just under 7/8" from the end of the airframe tube.

To glue the upper ring in place,

Slide the mount down, about 1/4" below the final position. 

This lowers the mount and upper ring. Epoxy can be applied from above, then the mount slid up into the epoxy glue ring.

 

I used a dowel to reach and apply a ring of epoxy glue.

With the upper ring in the lowered position, the dowel was marked to be used as a depth guide.

To reach in with the epoxy,

Roll just the end of the dowel in the glue. This is set into the tube up to the mark and rolled around the tube wall. 

Continued next post -

Aerotech Mega Initiator #89541, Part 10, Final Fin Fill & Dry Fits

The fins on the flight version were left square.

That inside leading edge angle still wouldn't match up. I added some CWF for a better flow.

Here's the same fill after sanding. Some 400 grit was wrapped around a pencil to sand the angle.

Another dry fit of the fins showed the ring slots were too tight.

The sides were shaved down, widening the slots.

Here's how far the engine mount is recessed, the ring face is just under 7/8" from the end of the tube.

With the fins in the slots set the placement depth of the  engine mount.

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.

Aerotech Mega Initiator #89541, Part 8, Ring Diameter Sizing

Both the inside and the outside edges of most rings need to be sized to slide into or over the tubes.

I used a combination of a sharp knife and a half round diamond file to slightly increase or decrease the diameters. I found that removing the laser ash brought them to almost the correct size.

The additional motor mounts need some sizing.

That smaller (inside) ring should slide into and almost "lock" into the largest mount tube.

That required a slight angle sand.

Sand a little, test the fit and continue until it friction fits into the larger motor mount tube.

This is the adapter bulkhead.

The instructions don't mention it, but put a washer on both sides of the ring. The screw eye and threaded bolt are locked in place with some epoxy.  

Aerotech Mega Initiator #89541, Part 7, Prepping More Parts!

I know there is a LOT of parts prepping - 

Ask any wood worker. The secret to a great finish is good surface preparation.

   

Here's that inside corner on the leading edge of the fins.

On the top picture - 

With the primer shot, you can see the mismatch of the rounded leading edge at the center of the angle. Some corrective sanding was done.

Here's the same corner after a directed shot of filler/primer. More careful sanding should get things in line.

The fin after the second coat of filler/primer - 

There were some small lines that needed some CWF and more sanding.

It seems every slot was a hair too narrow.

The root edge notches and the fin slots in the body tubes were widened for a better fit.

I could slide my sanding block into the slots using 220 grit.

The fins were test fitted. 

The joint of the body tube and root edge was very good now, tight enough with no distorion of the tube..

Aerotech Mega Initiator #89541, Part 6, Fin Filling

One of the fins had a knot hole fill.

It won't be noticeable with an easy CWF fill and sanding.

This fin will go on the flying build.

Here's that inside angle trouble spot I mentioned earlier.

When sprayed with filler/primer you can better see what needs to be cleaned up with better rounding.

The root edge and fillet areas were taped off for the filler/primer spraying

The fin in back is before sanding,

The fin in front is after sanding with 400 grit.

Here's a close up of the sanded fin surface. 

It's easy to see the gray filler left in the shallow grain.

Aerotech Mega Initiator #89541, Part 5, Fin Shaping

The fins are 1/4" thick, five ply plywood. The plywood is very high quality.

The instructions don't mention it, but I'm going to round the edges on the presentation model.

I drew a pencil line for reference all the way around the exposed outside edges.

I started by knocking down the edge at a 45 degree angle with some 220 grit on a block. Sanding with the block helps keep the width consistent.

The tricky part is where the concave edge meets at the break in the leading edge corner. This took the most work.

You won't be able to judge how well the rounded edges meet until you spray it with some filler/primer later on.

On the left,

is the first rough knock down of the right side trailing edge.

On the right is a good rounded edge on a different fin.

I wouldn't sand the blackened laser cut root edge until you check the fit before gluing the fins thru the wall and against the motor mount tube.

Aerotech Mega Initiator #89541, Part 4, Tube Fill And Prep

The presentation model main airframe tube got the seams filled. The picture shows the thinned CWF applied. The tubes will still get a good shot of filler/primer and sanding to complete the two-step fill. 

Even with the heavy walled tubes, you can still get some extra support by sliding in the coupler. This prevents any distortion of the tube when sanding at the weaker fin slot areas.

The engine mount tubes are sanded for better adhesion of the centering ring epoxy.

Here's that "zero end" metal straightedge, no rounded overhang.

It's easier to accurately position centering rings when you can get the ruler edge against the ring wall.

Don't glue the rings on yet. This was just a test fit.