Model Rocket Building Blog

Estes Orbital Transport, Kit #K-42 Background
This was the first real catalog I received from Estes. This 1970 catalog cover had a great impression on me. I had to have that cover rocket! By the time I requested one, Estes had ran out of their 1969 color cover catalogs. They ended up printing some "get-by" pages in black and white. Four ...
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Estes Orbital Transport, Kit #K-42, Part 2, Engine Mount
The engine mount is a standard 20/50 style. I'll be doing some minor upgrades. The upper centering ring is glued above the upper bend of the engine nook so no notch is needed. I did cut a "V" shaped notch for a Kevlar tie. The lower ring (upper left, the mount is shown upside down) got a notch for ...
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Estes Orbital Transport, Kit #K-42, Part 1, Parts
I forgot the parts post - #1!!! This will be a spare parts build. When you see it like this it doesn't look like there was much in the bag! Some changes -  A heavy wall BT-50H tube is substituted. The glider will still use a standard BT-20 to keep the weight down for a better glide. An Apogee ...
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Estes Orbital Transport, Kit #K-42, Part 3, Cutting Out The Balsa
Look at all the fin templates! In the kit these were printed on light card stock. NO die cutting, No laser cut fins in 1969. You would cut out the template, trace with pencil on the balsa (follow the correct wood grain!) Then cut them out with a sharp knife. The matching pieces may not be cut the ...
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Estes Orbital Transport, Kit #K-42, Part 4, Cutting Out The Balsa
I double checked the squareness of some parts with my engineer's square. Hold the balsa and square up to the light to check it. The two large wing pieces are glued together. Here they are under my trusty clear cutting board. The top has a pebbled surface, the underside is smooth. With the counter ...
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Estes Orbital Transport, Kit #K-42, Part 5, Wing Assembly
I had already filled the large rear wing pieces and then realized I didn't include the long forward strake! I filled the strakes with CWF. After they are glued on the assembly will get a shot of Filler/primer and sanding to fill the seam. GOTCHA: Interesting that the instructions have you glue the ...
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Estes Orbital Transport, Kit #K-42, Part 6, Scramjet Assembly
The open inside ends of the tubes got a wipe of CA glue. Sometimes I'll fill the inside seams if they are visible on the finished model. These scramjet tubes are BT-5 and small and not easy to fill. All the outside tube seams were filled with CWF and primer/filler. Two sets of tubes are glued side ...
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Estes Orbital Transport, Kit #K-42, Part 7, Scramjet Assembly
I checked the filled scramjet housing top piece from the laser cut sheet from BMS. I thought maybe I had sanded the piece smaller. The part may have been cut too small. The new center piece was longer and extended beyond the front of the top cover! More trimming and filling. There - that's better! ...
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Estes Orbital Transport, Kit #K-42, Part 8, Launch Lugs & Standoffs
Two launch lugs are cut to 5/8" long. I usually sands the ends flat and square with 400 grit on a block. The Mylar skin usually rolls over on the inside. Pick it out with the tip of your knife and sand it off. Reform the inside of the lug with a sharpened pencil or dowel. Turn the dowel in the ...
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Estes Orbital Transport, Kit #K-42, Part 10, Decal Correction
Working a bit ahead - I wanted the decals to read "ASTRON" like the original Estes kit. The decals I bought from Semroc read: "Semroc Astronautics Lines". This is not a big deal, I just wanted it closer to the model I built in the 1970s. To get an approximate point size, I measured the words ...
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Estes Orbital Transport, Kit #K-42, Part 9, Launch Lugs Alignment
The printed PDF tube marking guide probably wouldn't fit the BT-50H heavy wall tube. I went to payloadbay.com and entered the 50H diameter and an eight fin count. This fit the tube perfectly. The tube was marked for all the fins with pencil lines. OOPS! While I could use 4 of the 8 equal spacing ...
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Estes Orbital Transport, Kit #K-42, Part 11, Glider Surface Fill & End Disk
The glider wing and rudder parts are cut from 1/16" thick balsa. I hand picked out some balsa with very little grain. I rarely use the Hobby Lite filler. It's not really good for general rocket building but should be lighter than CWF and primer/filler. The filler was dry and needed water and a lot ...
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Estes Orbital Transport, Kit #K-42, Part 12, Wing Filling & Gluing
There's a LOT of balsa pieces! Everything was filled with sanded CWF and sanded primer/filler. Both sides of the wing were glued on using my Odd'l Rockets Fin Tool. These fins are far forward so I visualized the position through the slots in the base of the tool. The wing tips are glued onto the ...
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Estes Orbital Transport, Kit #K-42, Part 13, Glider Wing Fit & Fill
Notice the break at the butt joint of the two wing sides. Using a sanding block, a slight angle was sanded into both wing root edges. The sanded angle makes a better fit and a tighter glue joint. Glue is applied to one side of the wing. I don't use much glue so I can make adjustments if needed. ...
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Estes Orbital Transport, Kit #K-42, Part 14, Glider Assembly
The wing is glued onto the glider BT-20 tube. TIP: Don't even try to make a glue fillet in the tight wing joint. It would take too many bubbled glue fills adding weight to the glider. I did add a fillet to the front and rear of the wing - not down the sides. The glue side of the elevon was also ...
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Estes Orbital Transport, Kit #K-42, Part 15, Ventral Fins & Glider Support
Mentioned earlier, my eight fin evenly spaced marking guide doesn't work for the ventral and glider support fins. On the left you can see how those marks line up with the original kit marking guide. Good thing I double checked before gluing! I use very little glue to place fins on a body tube. ...
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Estes Orbital Transport, Kit #K-42, Part 16, Small Fin Placement
Here's a view from the top showing the glider support piece positions. The instructions say to glue them 2 7/8" from the rear. I glued them 3" from the rear so they didn't overhang the glider wing. The ventral fins on the bottom. It's a little tough getting the fillet on next to the rear launch ...
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Estes Orbital Transport, Kit #K-42, Part 17, More Fins & Pre-Paint
I used the old kit marking template for the wing fin positions. Pencil marks were made in three different locations by sliding the template down the main tube. There's not much filler/primer after sanding. Some 400 grit was wrapped around a Q-tip for cushioned sanding down the pencil line. The ...
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Estes Orbital Transport, Kit #K-42, Part 18, Scramjet Assembly Gluing
Yep - I should have glued these scramjets on earlier, but I wanted to get enough white paint into the inside edges. There are a lot of inside areas on the model. Some paint had to be removed for gluing. The scramjet assemblies were set in position then slide back about 1/16". The fronts of the ...
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Estes Orbital Transport, Kit #K-42, Part 19, Orbital Glider Decals
The gloss white finish coat on the glider was dry before the larger booster assembly. The Semroc Orbital Transport decals (and maybe the original Estes kit decals) are tightly arranged on the sheet. Look how close the glider decals sit next to the long red booster stripe decals. You might have to ...
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Estes Orbital Transport, Kit #K-42, Part 20, Orbital Glider Decals
Looking down from the top, the second "Astron Aerospace Lines" decal was placed. Normally I can coax a decal around a nose cone. Here I'm rolling a wet Q-tip over the decal to work out the wrinkles. Not this time! I had to make a small slice with a new razor blade on the wrinkle. This allowed a ...
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Estes Orbital Transport, Kit #K-42, Part 21, Booster Decals
Double check the scramjet decal positioning before the transferring onto the model. You would think the small end of the trapezoid shapes would face forward, but the wide end faces forward. The applied decal (above) is correct. Before soaking, dry wrap the decal around the BT-5 scramjet tube. ...
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Estes Orbital Transport, Kit #K-42, Part 22, Booster Decals
Again, the decals are arranged tight on the backing sheet. Cut slow and carefully so you don't go into another decal. The side stripe decal is narrow and long! You'll have to trim so it fits tight over the front canard fins. The inset picture shows a pencil line right above the rear edge of the ...
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Estes Orbital Transport, Kit #K-42, Finished
Another crossed off the list! I've been wanting to build the Orbital Transport for a few years. If an O.T. is at a club launch, I always watch the flight. A classic kit, well designed. The only negative thing is too many fins to cut out and fill! The clean decal treatment really make the model.
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