Model Rocket Building Blog
Semroc Baby Orion Build Part 1 PartsI had built and flown the original, big Centuri Orion years back. I was interested when Semroc brought back the full size Orion. I was more interested when I saw this downsized version. This one flys with 13mm T engines. Here's the interesting parts: The "tanks" are BT-3s. There are three tanks ...[Read More]
Semroc Baby Orion Build Part 2 Engine MountFirst up in the instructions are sanding the laser cut fins. Nothing out of the ordinary here, just be careful when rounding the pod fins. The balsa grain runs parallel to the short leading edge. It'd be easy to break the balsa. On this Baby Orion, there is no nozzle on the engine mount. I decided ...[Read More]
Semroc Baby Orion Build Part 3 Engine MountHere's two card stock shrouds after cutting out and forming on my hand with a dowel. Notice the tabs have also been curled a bit. After gluing closed, I'll use the best fitting shroud. Here's all the parts needed for the engine mount. (Not pictured is a BT-5 sized engine block I added later.) I ...[Read More]
Semroc Baby Orion Build Part 4 Engine MountWith that nozzle in place, ther'll be very little room for movement of the engine hook end. I cut off some of the bent end to make it easier to slide an engine in. For now, the engine hook was taped in place for positioning. The notched 5/20 ring was glued flush with the end of the engine mount ...[Read More]
Semroc Baby Orion Build Part 5 Engine MountThe lower centering ring was slipped over the top and down to the shroud. The upper centering ring was hard to get over the Kevlar knot. I had to make the notch bigger and set it over at an angle. Glue fillets were applied to both sides of the centering rings. With a wrap of electrical tape the ...[Read More]
Semroc Baby Orion Build Part 6 Small Wrap DetailsLooking forward to Step 27: "The original Orion had small parts attached to the wrap but were too small to provide with this kit at one-half scale. The yellow indicators on the wrap can be covered with small detail parts of your own design, if desired, or left as printed details." The original ...[Read More]
Semroc Baby Orion Build Part 7 Wrap DetailsFirst up are the half-rounds at the top of the upper wrap. As is my usual practice, keep the dowels long while shaping the front, then cut the back to the correct length. Sand off the back half of the dowel. Cut to the length needed on the Semroc decal wrap. TIP: Anytime you do small details like ...[Read More]
Semroc Baby Orion Build Part 8 Wrap DetailsOn the lower wrap is a two piece detail. The lower piece was a thinned down Popsicle stick. The upper round is a toothpick with the bottom sanded flat. After gluing the toothpick with CA, the front angle was made with 220 grit on a block. I matched the angle of the cut against the angle in the ...[Read More]
Semroc Baby Orion Build Part 9 Wrap DetailsThese little nozzles were the hardest to make. The front end of a toothpick was cut and sanded at an angle. I guessed at the pencil mark for the next cut. After getting a good shape on the first nozzle, the angles were drawn on card stock and three more toothpicks were cut using it as a template. ...[Read More]
Semroc Baby Orion Build Part 10 Wrap DetailsA couple more half rounds were needed on the lower wrap. The front was marked and sanded at the correct (or close) angle. The bottom is marked for cutting. I'll usually cut a little long and sand it to the right length. Here's the tunnel ready for sealing and sanding.[Read More]
Semroc Baby Orion Build Part 11 Details and FillingThis is all fourteen wrap trim pieces cut and shaped. These are not glued on yet. I'll seal all with varnish, two coats sanding between coats. All the parts needing filling are shown on the right. Seven nose cones, three fins, three standoffs, four body tube seams and a launch lug. The three BT-3 ...[Read More]
Semroc Baby Orion Build Part 12 Small Nose Cone ShouldersLooking ahead, I started thinking about the paint pattern. The nose cones would be painted blue before gluing to the tank tubes. The tube edge would give a good color separation. After sanding down the filler on the small tank nose cones, I noticed the gaps around the shoulder. On smaller cones ...[Read More]
Semroc Baby Orion Build Part 13 PrimerIf I'm building a model that is getting an overall color (like the Orion, which is white overall) I would normally glue on the fins before painting. This model is small, with lots of tight spaces, especially at the tanks and tank standoffs. So everything will be primed before gluing to the body ...[Read More]
Semroc Baby Orion Build Part 14 Fin GluingThere was nothing out of the ordinary in regards to gluing on the fins. Except, there is six fin positions. Three large fins and three tank standoffs. In the picture I tried a dry fit of the engine mount and nozzle assembly. The original Centuri instructions have the nozzle extending 1" out the ...[Read More]
Semroc Baby Orion Build Part 15 Engine Mount FixThe centering rings were too loose in the ST-10 body tube. I had to build up the diameter slightly. I cut some strips from 110 lb. card stock. Three were glued on and between the centering rings. To make it easier to start in the tube, the front end of the overhanging card stock was bent down to ...[Read More]
Semroc Baby Orion Build Part 16 Decal Wrap Plan?Sometimes the plan doesn't turn out right. I was going to use the decal wrap supplied in the kit then glue all the small pieces I'd made to it. I'd left the decal out when working on another project. Somehow, two drops of thin CA had dried on the decal. The CA had ruined the fine line detail on ...[Read More]
Semroc Baby Orion Build Part 17 Wrap InstallI'd drawn the wraps wide with plenty of overlap. The thickness of the paint probably widened the circumference of the tube. A long strip of 110 lb cardstock was wrapped around the tube and the overlap point marked. The cut length of the strip wrap was transferred to the printed wrap. The back of ...[Read More]
Semroc Baby Orion Build Part 18 Gluing Wrap DetailsAll the small detail pieces had been sprayed yellow. The wider pieces had their back sanded to a round contour to better fit the body tube. Any area that had a glued detail was lightly scraped to remove a little of the clear coat. Now the real fun starts, when you get to see all the small work in ...[Read More]
Semroc Baby Orion Build Part 19 Yellow Tank BandsI waited to glue on the three BT-3 tanks. I never would have been able to get paint coverage on the standoffs if the tubes were glued in place. These were sprayed off the model, a thin strip of masking tape went down one side to keep the tube clean for gluing. A 1/16" thick band of yellow Monokote ...[Read More]
Semroc Baby Orion Build Part 20 Masking The Nose ConeOriginally I was going to paint the model like the facecard art. I don't have a can of light blue paint for the small nose cones. So I decided to go with red for the six small nose cones and the tip of the larger main cone. There was already red in the Centuri logo and red stripes on the tank ...[Read More]
Semroc Baby Orion Build Part 20 Masking The Nose ConeOriginally I was going to paint the model like the facecard art. I don't have a can of light blue paint for the small nose cones. So I decided to go with red for the six small nose cones and the tip of the larger main cone. There was already red in the Centuri logo and red stripes on the tank ...[Read More]
Semroc Baby Orion Build Part 21 Masking The Nose ConeI used the Tamiya tape for this mask. Two overlapping pieces were set on my patio door glass. With direct sun, you should have enough light to make this work like a cheap light table. The printed transition was taped over the Tamiya tape with overlap on all sides. Carefully cut around the lower ...[Read More]
Semroc Baby Orion Build Part 22 DecalsThere were a lot of decals crammed on a small decal sheet. Take your time when cutting them out. I didn't like the word "Baby" at the top left of the name Orion. It was cut off and the Centuri logo put in it's place. Near and up the nose cone, the thin blue vertical stripes are hard to place. Wet ...[Read More]
Semroc Baby Orion FINISHEDThis one finished out shorter than I thought it would. A great downscale by Semroc. I probably spent more time building the Semroc Baby than I did the original larger Centuri Orion back in the 1970s.[Read More]
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