.: 2025

Thursday, June 26, 2025

Interceptor Scratch Built BT-60 Mash-Up... sort of a clone...

I have always loved the Estes Interceptor, they really knocked it out of the park with the design.

Here's a BT-60 29mm powered version that has design cues based on the original. Pods are reversed, decals are flipped. It's not a clone.. well... sort of.

2025-07-01 Nose Cone Turning

Turned the Nose Cone from a piece of 4 x 4 Pine, and the Cockpit from a 1" Dowel.

Updated the OR Simulation to match the as-turned piece.

Gluing the Nose Cone

Gluing the cockpit to the nose cone.

I've also learned that when the nose cone has a thin shoulder its a good idea to glue a coupler or a body tube into it. The thin shoulder can crack, the glued in coupler helps to prevent that.

2025-07-02 Fabricating Fins and Modifying Nose Cone

Cut the Fins from 1/4" Plywood and then sanded them to shape. Routed the edges with a 1/8" Rounding Bit.

Chucked the Nose Cone up in my lathe and tapered the front section down.

Gluing the Spears to the Vertical Stabilizers

Cut some 1/4" dia Poplar dowels to length, then sharpened them with a pencil sharpener.

Glued them to the Vertical Stabilizers using Gorilla Wood Glue. I noticed the spears weren't parallel with the bases, so I sanded the base down on my belt sander to make them parallel.

2025-07-03 Gluing The Fins.. Day 01

Using multiple fixtures to align the fins... I started with one, then went to the other. There really is no substitute for a good flat piece of plywood, with a cut-out for the body tube. Not real hi-tech... but it works very well.

2025-07-04 Gluing The Fins.. Day 02

Unclamped the rocket from the fin alignment plywood board. The Main Wings alignment came out nicely.

Time to install the (2) Vertical Stabilizers

So my fin alignment fixture has been relegated to holding the rocket while it dries.... I'm using the tried and true method of eye balling fin alignment for the Vertical Stabilizers.

The C-60 was marked with the fin locations using the wrap around template provided by OpenRocket. Wood glue is applied to the root chord of the 1st Vertical Stabilizer and then the fin is set in place onto the C-60 and held for about 30 seconds. Since the fins are made of plywood its easy to align the center ply with the pencil mark on the C-60. That's enough time for the glue to bite into the C-60, at which point it's set on the fixture for half an hour to dry.

The gluing procedure is repeated for the 2nd Vertical Stabilizer.

The rocket fins were then measured from Wing Tip to Vertical Stabilizer Tip. Measured distance varied by 3/16". I used masking tape and wrapped the fins from the Wing Tip up over the 1st Vertical Stabilizer, to the 2nd Vertical Stabilizer. I then moved the 2nd Vertical Stabilizer Tip to match the 1st Vertical Stabilizer Tip measurement. I then used another piece of masking tape from Wing Tip to the 2nd Vertical Stabilizer.

I'll let this dry 24 hours.

Ventral Fins and Wing Pods

Wing Pod Fit-Up

I used masking tape and a couple toothpicks to fit-up the Wing Pods to the Wings. I then used Gorilla Wood Glue to tack them into place.

2025-07-05 Glamour Shots

Installing the BT-60 Sections

Marked the front section of BT-60 tubing and then cut the slots for the Wings, Ventral Fins and Vertical Stabilizers. Applied a generous coating of Elmer's White Glue to the C-60 and slid the BT-60 into place. I then used a bunch of spring clamps and tape to hold everything in place while the glue dries.

Once that dried for 5 hours the lower C-60 was cut, glued and fitted.

2025-07-06 Fin Q&T Fillets and Spool

Made good progress today on the Fin Titebond Quick and Thick Fillets. Also cut the Spool parts and started gluing them together.

Sunday, June 22, 2025

GBU-57 series MOP (Massive Ordnance Penetrator)

Here's a semi-scale model of the GBU-57 series MOP (Massive Ordnance Penetrator).

It's a BT-60 based rocket that's rear eject, powered by 29mm composite motors.

12.5 ounces of nose weight is needed for stability in this configuration.

Monday, June 2, 2025

(BAR-50) Discovery Excalibur - A Scratch Built Odd-Roc

Spurred on by @BABAR's build on TRF, here's a scratch design and built odd-roc based loosely on the ship from the movie 2001 A Space Odyssey and the Excalibur from the TV series Crusade

This one is shorter and has a custom fin can arrangement.

29mm powered and rear eject

Some diagrams for ye ole interweb

Nose Cone - Turned from a pine 4" x 4"

2025-06-03 Cut some details on the Nose Cone, and bored a hole for the Altimeter Two.

2025-06-06 Forming the Elliptical Body Tube

I'm using my Tube Forming Procedure, but modifying it just a bit. This will be more of an elliptical shape, not an oval with straight sides.

Using a C-80 Coupler I made a wooden fixture that would make the ellipse 2.875" on its long side. I cut down a scrap stair tread and used (2) pieces that were 12" long.

Johnson's Paste wax was applied to the radiused sides of the boards,

The tube was soaked in warm water for 5 minutes,

The Coupler and Fixture were placed outside in the sun to dry.

This will be allowed to dry overnight before the wooden fixture is removed.

2025-06-07 Planning The Fuselage Build

I drew a sketch using the actual Elliptical Tube and Inner BT-204. My original intent was to make Centering Rings for the OD of the BT-204 to support the Elliptical Tube. That's not going to work well, especially since the Launch Lug actually cuts through the BT-204 side wall. So now the plan is to fill the sides of the Elliptical Tube with some Door and Window Spray Foam.

So a Rounding Fixture was made to fit inside the BT-204. This will serve a couple of functions, I can use the Rounding Fixture while:

Gluing the Launch Lug to the BT-204, wrapping rubber bands around it to hold the body tube and launch lug in place.

Gluing the BT-204 to the Elliptical Tube, it will keep the BT-204 Round while it is clamped at 12 and 6 o'clock

Use it to hold the shape of the body round when I spray foam in the outer cavities of the Elliptical Tube.

Also knocked out the BT-204 Adapter to glue to the Nose Cone, and cut a Centering Ring for the Nose Cone Shoulder also.

Little did I know... I was making a 3" Dia. hitch-ball....

2025-06-09 Started Gluing The BT-204 and Integral Launch Lug

Modified the Nose Cone Adapter to clear the Launch Lug, cut the BT-204 for the 3/8" Launch Lug, set up all the parts into the fixture, and started gluing.

2025-06-10

Pulled all the rubber bands and dowels this morning and the BT-204 / Launch Lug Ass'y is supper rigged and aligned perfectly. Sweet!

I love it when a plan comes together!

Cut the Fins They'll need some CWF... but all-in-all not to bad.

Gluing The Fins To The BT-204

Using my Fin Alignment Fixture for the 1st two fins.

And just winging it freehand on the last fin

2025-06-11 Gluing C-80 Elliptical to BT-240

Slots were cut in the C-80 to correspond with the fins, then a liberal amount of Gorilla Wood Glue was placed on the 0 and 180 degree lines that were marked on the BT-204. The Internal Rounding Fixture was installed inside the BT-204 and then the C-80 Elliptical Tube was clamped into place. The fixture really makes this sub-assy good and solid for the clamping operation.

Side Note: This fin can is not "Hell-For-Stout".

The fins are currently quite "flexible" being glued only to the BT-204. (I even used some pretty hefty Titebond Quick and Thick Fillets). The BT-204 flimsy side wall is the culprit.

Gluing the Fins to the C-80 Elliptical Tube should stiffen them some, as well as gluing the Fins to the Root Fin Strakes. That's all coming up next.

Still on the fence about using spray foam between the C-80 Elliptical Tube and BT-204... hopefully that won't be needed, but we'll see.

2026-06-12 Fin Fillet Dowels

Turned the Fin Fillet Dowels on the lathe, then sliced and diced them so they would fit. I used a 3/8" Forstner bit to remove some of the Pine as a weight saving measure.

Looking forward to gluing these onto the Elliptical Coupler / BT-204. Should further stiffen the fins, and add some sci-fi goodness too.

2025-06-15 Day 03 of the Fin Root Dowel Gluing

Gluing the Fin Root Dowels took some time, due to the gaps and the glue drying, but they came out nice.

Modifying Nose Cone For Ballast

The Nose Cone was drilled with a 1/2" wood bit for a 1/2" dia. x 3" long steel Ballast. Then a Wooden Dowel was turned on the lathe to fill the hole in the shoulder.

The ballast was slid into place, and the wooden dowel glued into the shoulder end.

The dowel was later drilled and a 3/16" dia. Lag Screw Eye was screwed / glued into place.

Gluing the Nose Cone to the BT-204

A liberal amount of glue was placed inside the BT-204, as well as on the Nose Cone Shoulder. The Nose Cone was then slid into place. A 5/16" dia. wooden dowel was run through the Launch Lug and the hole in the Nose Cone, and left in place to assure alignment while the glue dries.

A 1/4" dia. hole was punched in the BT-204/Elliptical Tube to inject glue between the Shoulder and the Centering Ring. This will allow injecting glue to create fillets with the BT-204.