Thursday, December 18, 2014

FlisKits Mercury Redstone Build Part 7 Tower Step 1

I emailed Jim Flis about wanting to build the tower instead of using the card stock tower supplied in the kit.
He sent templates and a heavy card alignment stand for gluing it all together.

On the left are the drawings Jim Flis sent.
On the right are some drawings of the Redstone capsule and tower I already had.

The Flis supplied drawings give you the basic tower sides and strut lengths. The horizontal and diagonal strut ends touch on the Flis drawing.

On the actual Redstone tower, the horizontal struts go all the way over from side to side.
The diagonal strut ends are welded directly above and below the horizontal struts.

On this build I'll glue the horizontal struts first and then add the diagonal struts with the angled ends butted up against the horizontals.

Secrets of Estes Modeling, Part 1

In a blog comment, David Carllucy sent me the link to this article by Mike Dorffler telling how Estes builds their catalog models. This copy was in Sport Rocketry magazine but is worth repeating. 

      Secrets of Estes Modeling
by Mike Dorffler, Estes Industries

We break down the method to build a good quality model into specific tasks, then bring these together almost like an automobile assembly line. We plan it out before we start. That way if you screw up one task you can redo that portion and go on. It's much more difficult to completely build the model and then try to paint it. We build the engine mounts, fins, body tube assemblies, etc., finish them as necessary, then bring them together.

We do fins like this. First of all, we replace the balsa with basswood. It's nuts to try to fill and finish fins made from balsa. The basswood is much finer grain and finishing goes so much faster, the results are superior. Go find yourself some Sprayon brand industrial primer light gray #00341. Peel the sales label off the basswood sheet and use some lacquer thinner to rub away any of the adhesive left on the wood from the sticker. Use some 400 wet or dry paper and sand both sides of the sheet smooth. Then stand the wood up on one end against a cardboard box or similar and power drive a heavy coat of the primer into one side. Let this dry and repeat for the other side.

Sand again and paint again. Then sand the sheet again almost back down to the wood itself. Once you have tried this you will immediately see why it works so well.

Now use the balsa fin you are going to replace as a pattern and trace it on the basswood sheet the appropriate number of times. Cut the fins out with a razor blade or X-Acto. We don't use a bandsaw because the fin edge will chip no matter how careful you are. Sure, you could cut them about a 1/16" oversize and sand them back, but it's more work than just blade cutting them in the first place. Sand the fin edges smooth while occasionally stacking them all up to see if they match. Take the 400 and just kiss the edges where they meet the fin sides to make a small radius. Don't make the effort to try to radius all the fin edges. I don't want that. They look better if the edges look almost square. Put a piece of plastic bag over the end of your finger and seal all the fin edges with cyano EXCEPT the root edges. You can actually do this now or after the fins are attached.

We seal the body tubes with a heavy coat of gray primer, sand, seal again, and then sand again. Use whatever tube marking guide or method you choose, but use only a pencil to mark the tube for fin and launch lug placement.

Anything but pencil will get absorbed by the paint pigments. We run straight lines the entire length of the tube so you can sight down them when attaching the fins. Also, to get the lines straight we use two-foot lengths of 1/2" aluminum angle. You just lay it on the tube and it's automatically straight.

First run a set of alignment lines the length of the tube, spaced appropriately for the fins. Then run another set next to the first, spaced the thickness of the fins. The idea here is that you will attach the fins BETWEEN the lines and you can see immediately whether they are straight or not. Now take your pencil and put cross marks on the tube where the fins are going to be making narrow rectangles. Use a narrow sanding bar or those little finger nail sanding strips to sand through the primer and back down to the 'brown' of the body tube.

Build the engine mount, test-fitting it in the body tube as you go along. Paint it flat black when done. Also paint the inside of the body tube flat black where the mount will go just deep enough so that you can't see the brown on the inside. Install the engine mount using epoxy. We use the 15 minute type which allows enough time for adjustments before it sets. We don't use Titebond here because, when it dries, the water in it makes 'coke bottle' type impressions around the body tube where it was applied inside.

These are the Estes methods for building catalog and trade show models.
Over the years I've used similar ideas, like building in sub assemblies and filling all grain and seams before gluing it all together.
Interesting to note: "It's nuts to try to fill and finish fins made from balsa." But, balsa (or now Tung wood) is included in most all kits.
On occasion I use basswood, it's stronger and easier to finish.
Mike mentions using epoxy for engine mounts: "We use the 15 minute type which allows enough time for adjustments before it sets." We've all figured that one out! 
I wouldn't recommend painting the inside of the engine tube flat black, that might interfere with inserting an engine. Again, this is how they build for catalog and face card pictures.

Wednesday, December 17, 2014

FlisKits Mercury Redstone Build Part 6 Fin Air Rudders

Here the pencil lines are drawn down the taper line using the extended lines already drawn on the instruction sheet.

Cut the basswood edge off down to the leading edge on both sides of the Air Rudders.

I used a four sided fingernail file to taper the Air Rudders first.

The Air Rudder squares were a little loose on the basswood.

I added strips off packing tape to both sides to help hold them onto the sheet.

Use the pencil line as a taper reference.
The leading edge tip is a knife edge.

Sand the tapers on opposite sides. The kit included six air rudders. Four will be used in construction, two are extras.

Fillets! Tips, Part 2

After smoothing down the root edges, roll a Q-tip over the front and back end.
This rounds off the ends, removes any excess and can push some glue into the seam crack at the ends.

Remember, the T M&TG skins over quickly. Don't go back and try to remove any more after the first or second smoothing of the glue.

You wont be able to sand white glue or T M&TG fillets!
I usually give the model an additional shot of primer filler and sand that. If there are any glue ridges left they should go away after sanding the primer / filler to surface.

Titebond Molding and Trim glue is like any other new tool. It takes a few tries to get it right. I didn't like it at first but now use it on almost every model.

Here's an example of some finished paint over fillets.

Personally, I think the width of the fillets should reflect the size of the model and body tube.
LPR models get thinner fillets. MPR models get wider fillets usually formed out of epoxy.

Tuesday, December 16, 2014

FlisKits Mercury Redstone Build Part 5 Fins

This shows how the burnt brown edge shows the taper shape.

The closest edges has been sanded, the fin will be flipped over and the other leading edges tapered.

Be sure the width of the brown edge is consistent.

On the left - the outside edge of the Main Fin with the burnt edge (and hold down tab) before sanding.
On the right - after sanding the outside edge.

Don’t sand off too much or change the shape or size of the fin.
Just sand enough of the burnt edge to smooth off the hold down tab for a better gluing area of the cardstock Fin Tip piece.

Fillets! Tips, Part 1

At a club launch I was asked how I got fillets that were thick and smooth.
Like everybody else, we all used white glue fillets, that's what the instructions told us to do.
White glue shrinks and bubbles will form, especially in deep fillet areas around the launch lug.

I glue the fins in place and apply the first fillets with white glue.
After those dry another fillet is applied using Titebond Molding and Trim Glue. I always refer to it on the blog as T M&TG.

The fillet at the bottom is a smoothed Titebond M&TG fillet.
The top fillet is the T M&TG right out of the bottle, not smoothed yet.
TIP: The Titebond nozzle top spreads a glue bead that is too wide. Replace the Titebond nozzle with a orange top from a bottle of Elmer's glue. You do have to squeeze harder to get the thicker T M&TG out of the orange Elmer's nozzle.
You won't need any more glue than what is shown here. Too much glue makes a wider fillet pool when spread with a finger.
Start smoothing the fillet from the center to the ends.

Don't wait too long before smoothing out the just laid down glue. The T M&TG skins over pretty quick.
Instead of smoothing the entire fillet from top to bottom -
Start at the middle and go to the top. Go around the front of the rounded fin tip leading edge.
Wipe off your finger and smooth again.

Then go from the center to the rear of the fin.
Why two steps?
If you were to smooth the entire length of the fin root you end up with a good sized bead or pool of glue at the bottom.
Doing it in halves keeps a smaller amount of glue under your finger at the end of it's "half travel" down the fin root.
Continued on next blog post . . .

Monday, December 15, 2014

FlisKits Mercury Redstone Build Part 4 Main Fin Tapering

As before, set the main fin on the instruction drawing and draw the taper line down the fin.

Leave the fins on the sheet. Sand two fin leading edge tapers at the same time.

As you are sanding, stop after a few passes to check the thickness of the taper.
Use the dark laser burnt edge to better judge the edge width.