Special Hobby 1/48 X-15A-2 Build Update 3

Time for another update. Progress is continuing on the X-15A-2. I have the external tanks primed and the first color applied.

I then moved to a part that I’ve been procrastinating on. The windows on the cockpit canopy have to be cut from a supplied square of clear plastic. I started by cutting out a rectangle of the approximate dimensions and then I carefully sanded the rectangle into an oval shape that will fit the openings in the cockpit canopy. It actually wasn’t as difficult as I was imagining. It did take a while to get a shape that fit, but careful sanding slowly created window that fit well into the opening. In the picture below if you look closely you can see the window in place. I used Plasti-Zap CA glue. It does not fog clear plastic, but holds the parts together very tightly.

I then shaped another window for the other side. I only dropped a window into the carpet once. Fortunately I was able to find it and didn’t have to shape another window. Once they were glued in and the glue cured, I used some alcohol on a cotton swab to clean the windows both inside and out. I then brushed on a coat of Future Floor Finish on both sides of the windows. It not only makes the windows very clear, but it also helps to hold them in place similar to the glue.

Next I applied some Tamiya masking tape and used a fresh #11 blade to mask the windows for future painting.

It was now about time to glue the fuselage halves together, but before I could do that I needed to nail down how the model was going to be displayed. Special Hobby does not provide any stand for the model if you build it as an in-flight version. My friend supplied a stand that he had bought some time ago. He and I were both fairly sure it would not work. Once the external tanks were mounted, the stand would not fit between them. I looked on the internet for an alternative. I thought I had found one, but after it arrived and I started doing some fit checks, I realized that it wouldn’t work very well either.

The stand had a very long chrome bar that came up from the wooded base. Since the X-15 has a substantial ventral fin, this stand would have required the model to be mounted just behind the cockpit. That was the only way to be sure the ventral fin would not hit the chrome bar. This would have resulted in a very unstable mount. So back to the internet I went. I finally found one that looked narrow enough and had flat metal bar that would be next to the model that was only and inch or so long. That would easily clear the ventral fin.

When it came in I was even more pleased. It included a threaded insert that could be glued into the model and then it had a thumbscrew that secured the model to the stand. It also had another short pin that went into the model and prevented it from spinning on the thumbscrew. Here some photos of the model with the holes drilled and the threaded insert in place, but nothing is glued in.

After verifying that this was going to work, I added a small styrene fence and then poured epoxy all around the threaded insert to permanently affix it to the model.

Now finally I could glue the fuselage halved together. The halves were slightly warped, but that was easily taken care of by gluing the halves together bit by bit from the nose toward the rear. When I was about a third of the way down I shifted to the rear and moved forward. It went together pretty well. I used Tenax 7R and it welded that halves solidly.

It required a bit of seam scraping and some filler. Then I needed to re-scribe some panel lines where they cross the seam. I then epoxied the ejection seat into the cockpit. It looks pretty good. I didn’t go all out on the instrument panel since so little will be visible through the tiny windows.

The canopy didn’t give me as much trouble as I was afraid of, but it did take a fair bit of sanding, scraping and re-scribing.

The wings gave me more trouble than I was expecting. They were both warped. I hadn’t noticed this before, but then I wasn’t really looking at them very closely at the time. I soaked them in boiling hot water for a few minutes and then took them out and carefully bent them to remove the warp. I wasn’t able to get all the warps out, but they are now visibly straight and you need to look closely to see the remaining warp.

I also attached the horizontal stabilizers. Now it is really starting to look like an X-15.

The external tanks have been painted. All that is left is to paint on the final few details and then spray them with a clear coat prior to adding the decals to them. I’m sure that I will have to run a drill bit through the small holes to remove the bits of paint and clear coat so the 0.015 rod will pass through.

That is it for now. Thanks for looking.

Special Hobby 1/48 X-15A-2 Build Update 2

It has been a while since I posted on this build. I’ve been a little busy with other things and couldn’t find time to write a post. I’ve been working on it, just not enough time to post. Anyway, this post will probably bit a bit longer than normal.

I finally finished with the nose gear door. The scoop door required a lot of reshaping to fit the hole. I suppose it would have been less noticeable if it was modeled with the gear down, but with gear up you have to carve quite a bit off to make it fit.

You can see from the above photo that the RCS nozzles were drilled out. The original molding was just a small circle. Here is a set of before and after photos:

Next I painted the cockpit parts. Mostly gray with some black panels, gauges, yellow eject handles, red cushions on the seat and headrest, and some orange on various parts of the ejection seat.

Now to glue the nose gear well into the bottom half and the instrument panel and cockpit tub into the upper half.

Now I needed to tape the upper and lower fuselage halves so I could do a preliminary balance check. I want the model to have a CG near the center so it will fit on it’s stand with out trying to pull itself off from the front or back. When I went to hold the model halves together so I could tape them, I noticed that the front of the fuselage would not close.

The edges of the cockpit tub were to straight and were interfering with the curvature of the lower fuselage. I got some coarse sandpaper and started removing material. Basically I was rounding the edges off.

I was then able to close the fuselage halves.

Continue reading “Special Hobby 1/48 X-15A-2 Build Update 2”

Wild Thing Vintage Kit Build Update 5

Time for another update. I’ve filled the spirals in the false motor tubes and sprayed primer on them to check for missed spots. The photo below shows the end with the fin alignment guide on and the first two fins tacked in place.

Here is a view with all the fins tacked in place and the alignment tool removed.

Next I began pouring 30 minute epoxy down the fin roots to get them firmly attached. This took a while since I could really only effectively do two fins at a time. Then I needed to let them set up so I could rotate the airframe and do another two. Also, since I needed to get epoxy down both sides of the fin roots, it still took seven rotations to get them all done. Here is a look down from the end. The lighting is bad so you might not see much epoxy but it is there.

After all the roots had cured I more or less repeated the process to be sure that I got a good joint all the way down. I then needed to pour fillets for the fins where they meet the dummy motor tubes. I used some clay to plug the end and keep the epoxy from running out and all over the motor tube.

I then poured epoxy into the area and made sure the tube was barely in a nose up attitude. This allowed the epoxy to flow and level without all of it leaking down the front of the fin. I did make sure that some epoxy did flow down the front edge of the fin into the void below. That made for a nice smooth fillet line from the leading edge to the trailing edge.

I then mixed some epoxy with microballoons to make a paste that I could use to fill the voids between the dummy motor tubes and the main motor tube. The picture looks ugly, but when looking at it by eye it is relatively smooth. I’ll see what it looks like when I spray primer over the whole bird later.

Next I need to start working on the nose cone and then can come the painting. Maybe I’ll be ready for a test flight in August?

Thanks for looking…more to come.

Wild Thing Vintage Kit Build Update 4

More work has been done on the Wild Thing.  I drilled four small holes through the motor tube and into the 5/8 inch plug.  I then epoxied 4 short sections of dowel into the holes.  These will serve two purposes.  First, they will provide a bit of an additional anchor for the plug to prevent it coming loose during recovery.  Admittedly a small chance but why risk it.  They will also prevent me from pushing the forward end of the baffle too far down the motor tube.

I then used the bulkhead I’m not using to mark the fin positions.  This will help me get the fin alignment correct.

I then pushed it on to the back of the rocket over the 38mm motor tube.

Next, it was time to epoxy the motor mount assembly into the main tube.  I first marked on the outside the position of each of the centering rings.  This would help me figure out where to smear epoxy on the inside so I would be sure to push the ring through the epoxy on its way to its final position.  Since there were three rings on this motor mount, I needed to smear epoxy for the top ring first.  Once I had it smeared all around the inside of the tube I started pushing the motor mount in.  Before the next centering ring went inside the tube, I smeared its epoxy inside the tube.  Then continued pushing the mount in until I was nearing the last ring.  This ring basically fits flush with the end of the main tube, so I smeared epoxy at the end of the tube.  I then pushed the mount in the final amount.  Once that was done I stood the rocket up on its business end as vertical as I could get it.  I was using 30 minute epoxy for this, so I let it cure for a couple of hours before I laid the rocket over.

Now I needed to glue in the upper baffle bulkhead.  I mixed up about 10ml of 30 minute epoxy and put my rubber gloves on.  I smeared a bit of epoxy just above where the bulkhead was to go and then pressed the bulkhead into place.  I then used a finger and scooped out some epoxy from the cup and smeared it around the tube/bulkhead joint.  I also smeared some around the motor tube/bulkhead joint.  I again stood the rocket up vertical until the epoxy had cured.

I then installed the rail buttons.  The lower button was screwed into the centering ring at the base of the main tube.  The upper button was installed just above the upper baffle ring.

I need to fill in the spirals on the dummy tubes.  I could have glassed them but that would have made it difficult to get them installed on the centering rings, and made it harder to get the fins on.  It won’t be too bad to get them filled. Then it will be on to the fins.  I’ll start by rounding the edges.  Then they will get glued in according to the alignment ring I made.  Anyway that will be a future update.  That’s it for now, thanks for looking.

Special Hobby 1/48 X-15A-2 Build Update 1

Work is continuing on the 1/48 X-15.  At the end of the previous post I showed the progress on the dorsal vertical stabilizer.  Well, after looking at it, and then doing some dry fitting, I discovered that the wedge should have been flush with the back of the fin sides and the resin back piece should have been put in below the wedge.  So I removed the back piece and then cut a small piece of .01 x .01 inch strip and glued that to the back of the wedge.  Then I re-installed the resin back piece.  Here is how it looks now.

I then moved on to the ventral vertical stabilizer.  It seems that most of the edges of the parts in the kit do not have vertical edges.  They are angled.  I guess for a short run kit they may have done that to make it easier to release from the mold.  It doesn’t help with the fit of the parts as it requires most edges to be sanded to get a good glue joint. Below is an example.  It is the wedge shaped fin edge piece.

Anyway, before I started work on the ventral fin, I notice that the sides of the dorsal fin had a slight curvature.  To correct it I inserted a small strip of .01 x .01 styrene.

I then got ready for the ventral fin.  When reviewing my research data, it looked like the ventral fin was slightly shorter than the dorsal fin.  Why didn’t I notice that when I was doing the 1/144 scale version?  Well, it turns out that both of my 1/144 scale X-15’s were modeled with only the fixed portion of the ventral fin that contains the air-brake.  So, I dove deeper into my research data to find some dimensions and sure enough, the ventral fin is 11 inches shorter at the back and 9 inches shorter at the front.  I guess I just never paid enough attention to that before.  Anyway, I converted those dimensions to 1/48 scale and drew then onto the ventral fin inside face as seen below.

The lowest line coming off the curved lower edge was to get a measurement line.  The next line up shows the fixed portion of the fin.  Finally the top line shows the amount that needs to be removed.  I made the same marks on the other side and then started cutting off the excess.

In the meantime I primed some of the parts to help highlight any areas that might need some more work.

I then did a little work on the nose gear door.  It required quite a bit of sanding and shaping to fit properly, and I still don’t have the scoop door added yet.  As an aside, the scoop door is what allows the nose gear door to open at a high angle of attack, otherwise the air stream pushing against it would keep the nose gear door from opening.

Back to the ventral fin.  The movable portion of the ventral fin is ejected before landing otherwise the fin would hit the ground before the skids did.  The ejected portion had a parachute in it so it could be recovered and reused.  This meant that I needed to model a parachute door on the back side of the fin.  The supplied resin part didn’t have any provision for a parachute door and it also had piping molded in that never existed on ventral fin of the actual plane.  Removing the piping would pretty much destroy the part.  So it was just easier to scratch a new one.  I took a section of .01 sheet stock cut to the proper shape and then marked where I wanted the door to be.  Next I glued on sections of .01 x .01 strip stock to represent the corrugations.  Then I cut a rectangle of .005 sheet stock to represent the door.  Onto that I glued some more .01 x .01 strip stock.  I then glued that to the gap in the strips I had left.  Here is a photo of the original part and my scratch build replacement.

I then went back to the ventral fin and started construction.  I began as I had with the dorsal fin, by gluing the leading edge.  I then added the top wedge, followed by the new back piece.  I also added the resin top of the air-brake.  Here are a couple of photos.

Here is a side by side picture of the dorsal and ventral fins and their size difference.  Note that I also have added some filler to both parts as well.

That’s it for now.  I should be getting to the fuselage soon.  I have some painting to do on the cockpit parts before I can start on the fuselage.

Thanks for looking, more to come.