Thursday, September 30, 2010

Semroc Little Joe II Build Part 18 Tower

No doubt about it, the tower is a tough build!

The outside four sides weren't hard to glue up, but the inside V strut assembly took too much effort.
Earlier, the O ring (in the middle) was split and half was used on either side of the V struts.
I did my best to line it up, but there is still a rough edge facing out.
In the picture to the left, the upper V legs haven't been glued down yet. This is another reason not to glue the V tips together until now. The V (hinge) can be spread open for a better fit.

A raised glue bead was applied to the outside of the ring with a toothpick. I didn't really smooth the glue, it was left to dry and shrink covering any rough edges.

Semroc Little Joe II Build Part 17 Tower

The Semroc instructions have you glue the tower onto the Command Module capsule before the V strut assemblies are in place. I found it easier to glue them in place now. Looking ahead, I wanted to spray paint the tower and get all the dowels and glue joints smooth before gluing it to the capsule.

I actually had to do the "V" strut assemblies twice to get them right!

On that first try, the legs of the "V"s were glued together as a group of four. The ring was glued on top of that. I tried to insert it into the tower from the top - big mistake! Note to self: Go up through the bottom, it's a bit wider! During all the placement adjustments, the split "O" ring got bent in four places, between the V tips.

On this second and successful try, a cruciform pencil line was drawn over the assembly jig - shown under the assembly at the right. I drew tick marks on the ring so I knew exactly where to glue the V tips. If this assembly were glued together "flipped over" like in the instructions, you can't see under the ring to tell if the V tips placement is even.

I glued just the V tips down on the pencil marks. This was I was guaranteed equal spacing between the four Vs.

Notice in the picture the leg ends are not glued together. This will act almost like a "hinge" and be flexible enough for adjustments inside the tower.

As mentioned before, the larger assembly should go in from the bottom of the tower. Trust me on this, the tower base is wider that the top. Use tweezers to get the legs in place around and inside the four tower side dowels. Those end tips of the Vs should fit against the tower sides.

The smaller V strut assembly goes in from the top of the tower. After all that fiddling with the lower assembly, the upper one goes in easily. Here's the top view and you can see how the Vs sit on the tower sides. This picture was taken before the upper V was glued in place.

Wednesday, September 29, 2010

Semroc Little Joe II Part 16 Tower

Here's the tower sides, all four glued together.

One thing I learned after the tower sides were glued - every other "Z" diagonal brace side should be reversed as shown in this drawing. (Click on the drawing for an enlargement)
The "Z"s on my tower all face the same direction. Most people wouldn't even notice.

It's only after I looked at some scale drawings that I noticed the change in the "Z" diagonal bars.
The tower viewed from the back shows some of the gluing.
When first gluing the tower sides together, I don't use much glue. This way it's easier to make some adjustments if things aren't right. If all placement is good, I do heavier gluing like shown in the picture.

Tuesday, September 28, 2010

Wolverine Downscale "How To" Part 2

I realize some of this information is known to experienced modelers.
It's repeated here for the benefit of a younger builder or anyone curious about the process of downscaling.

If you are new to the hobby, you might find yourself spending too much time at JimZ's plan site.
You'll find it HERE

The Wolverine instructions are there - click on the Estes logo and scroll down to the Wolverine, plan #0816.
The fin plans are included, but I couldn't get them to print at the correct size. They were way too large! Some plans have a 1" square for reference, this drawing didn't.
A quick post on TRF got me the fin dimensions for my size reference.
Thanks to John Brohm for measuring the fins right through the kit bag!

I wanted to downscale the model from it's original BT-50 to a BT-5 main frame.
Normally you'd divide .543" (BT-5 downscale diameter) by .976 (BT-50 original diameter) to get a downscale factor of .56.

TIP: Using the Scale Factor Charts found HERE
I reafirmed my factor to be .56.
All the original measurements would be multiplied by .56 to get the smaller model dimensions.
Thanks to Jay Goemmer for putting together these valuable charts!

Semroc Little Joe II Build Part 15 Tower

The best recommendation I can give you on the tower is to take the extra few moments to get the strut end angles correct.

It's a fine line here - you want a slight friction fit between the two outside (thicker) legs but not so tight to cause them to bow out.

You should use waxed paper under the glued dowels. I took this picture without it for clarity.
I didn't find it necessary to pin the "Z" shape in the middle, that slight friction fit was enough to keep them in place. The lower, shorter struts will take pins to keep them against the bottom of the "Z".

Here's the lower "V" struts pinned and glued. Lots of pins here! As mentioned before, the "V" tips are cut off after drying.

I don't use a heavy glue blob over all the strut joints. I'll apply a small drop and wipe off the excess. This pushes glue into the joint and around the joint closing up any cracks. To do it right, you'll have to apply glue a few times because it will shrink.

Sunday, September 26, 2010

Bad Estes Instruction Drawings

I put a lot of time into producing the instruction sheets for my Odd'l Rocket kits and other vendors. I know how much time it takes to get everything in it's place.
With all due respect to Estes, some of these are pretty funny.

When I was looking through the Estes Saturn V instructions, I ran across the "Countdown Kid".
Please, find this kid a new hair stylist.
You'd think he would cover his mouth when coughing.

A scary monster hand packs a parachute from
the K-5 Apogee kit instructions.

Who can forget the talented "Talking Paint Brushes" from the old Estes Saturn 1B instructions.
Insert you own cartoon voices here.

The "Evil Eye" lines up the tailcone marking guides
on the V-2.

A personal favorite and source of nightmares, some of the suggested paint schemes from the Astron Spaceman kit.

That top row, middle drawing has Eddie Cantor's eyes.

Estes Saturn V Instructions

If you haven't got your Estes Saturn V kit yet, the instructions are available for viewing from the Estes website:

These instructions are dated from 11/98 and still have some North Coast Rocketry product pictures on the last page.

Friday, September 24, 2010

Semroc Little Joe II Build Part 14 Tower

Take a close look at the Semroc tower pattern.
With a pencil and straightedge I've extended the cut lines past what was printed on the pattern.

This makes cutting the dowel length and angles easier. You can't see the cut lines if the dowel is sitting on top of them.

Keep track of how many pieces you've cut. If you aren't going to do be gluing up the tower right away, keep all the pieces in a Ziploc bag. They are small and too easy to misplace.

I did all the cuts using a single edge razor blade. Line up the thin blade over the extended pencil lines you drew.
Note: The lower "V" struts are a little longer than the upper "V" struts.

If you enlarge the picture, you can see the sides were glued together before cutting off the top of the "V".
The sides were allowed to fully dry and the "V" was held steady over the template. A razor blade was set directly over the exteded pencil lines and the tip was cut off.

Semroc Little Joe II Build Part 13 Tower

In Step 8, two of the four 1/12" diameter dowels are sanded down to .058 diameter. The other two are sanded to a new diameter of .041.

On the laser cut card stock sheet there are "feeler gauges" to help you get to the final diameter. The gauges are shown below the ring in the first picture of Post 12.

For sanding, I held the dowel between my fingers as shown in picture. this allowed me to roll the dowel toward me between my thumb and middle finger. The index finger held the dowel down on the sanding block.

The instructions recommend sand away from you, then turn the dowel sightly and repeat.
I sanded toward myself, turning the dowel as it traveled over the sandpaper. The index finger provided pressure on the dowel as it was turned. Be careful, I got a blister on the side of my middle finger from the dowel rolling over one area over and over.

Just about when the dowel feels like it's ready to break, you should be very close to the diameter you need for the thinner .041 diameter dowels.

As you are sanding, you need to constantly check it in the feeler gauge. Set the dowel in the hole of the gauge, then try to slide it into the adjacent slot. If it doesn't fit in the slot, the diameter is still to big.

Thursday, September 23, 2010

Estes Wolverine Downscale "HOW TO" Pt.1

UPCOMING PROJECT - I've been away from home for the past three days and have been posting some Little Joe II steps that have been saved earlier. Until I get back home tonight, here's something I've just started working on.

I had a great time downscaling all the GooneyBirds, Sky Writer and A20 Demon.

Through these series of posts, you'll see the process to do the art for making a downsized "carded" model rocket.

The carded models I've made require very little painting. You print out body wraps and glue them to the appropriate sized tubes. These are stronger than the usual rolled 120 lb. card stock models. The fins are a printed ply "sandwich" folded over cereal box cardboard.
The nose cone on this model is balsa. It's the only part needing filling and painting.
To me it doesn't look like a downscale unless the finished model is about half the size of the original. It wouldn't really be a downscale to go from a ST-10 to a BT-50. It's too subtle of a change in diameter and length.

The Estes Wolverine is an interesting candidate for downscaling, Larry Renger was the designer. It was kit #0816 available from 1973 through 1979. Powered by a "T" engine model it had a BT-50 airframe. A BT-50 is on the large side for a mini engine power. This downscale will be BT-5 based and could fly with anything from a MMX to an A10-3T engine.

Semroc Little Joe II build Part 13 Command Module

The shroud has been formed the large ring edge tapered.

Here's a top view of the assembled parts up to step 7.
The escape tower motor unit (Step 2) isn't glued together yet, clay nose weight will go into the BT-3H tube.

The fit of the large tapered ring on the shroud was perfect.

Semroc Little Joe II Build Part 12 Command Module

One of the more unusual parts is the large ring on the laser cut sheet.
You can see how thick the outside cut seems to be.
The two slots under the ring are the diameter guides for the tower dowels.

There outside ring is actually three cut three times. The outside ring is cut entirely through the heavy card stock.
The two rings inside of that are immediately inside that are cut partway through to match the angle fit of the command module shroud.

Here you can better see how the rings roll off with a rub of your thumb. Follow up with a angle sand with a sanding block and it matched up with the shroud very well.

Semroc Little Joe Build Part 11 Capsule Parts

Here's all the capsule and tower parts.

And, a close up of the unusual pieces.

The two balsa ends of the escape tower motor unit are one piece and are cut apart. You aren't told to cut them apart in the instructions, but the illustrations in Step 2 show them as two pieces.

The Command Module nose cone is different from any other kit I've made.
It's made to fit a shroud and ring adapter.

The large cardstock sheet has the shroud and templates for cutting and gluing of the tower.

Semroc Little Joe II Part 11 Apollo Capsule Kit

The 1/70 Scale Apollo capsule kit is included in the Little Joe kit bag.

This brings back memories from the time I tackled the Estes Saturn 1B in the mid 1970s!

I hope to do a better job of it this time.

Wednesday, September 22, 2010

MMX Igniter / Toothpick Debate

Yesterday, there was a good discussion on The Rocketry Forum (TRF, click HERE, post 12) about toothpick / igniter retention in MMX engine nozzles.

Apparently, pushing a round toothpick in a round MMX nozzle could lead to overpressure and possible explosion of a Micro Maxx engine. The toothpick shouldn't be crammed in like a plastic igniter plug used in 18mm or larger engines.

In an earlier post (click HERE) I wrote of my success using a square toothpick (instead of a round one) to hold the igniter in the small MMX nozzle. The square toothpick might allow some pressure to escape and prevent an engine CATO. Picture a "Square peg in a round hole".
Some posts agreed that square toothpicks could be the way to go with igniter installation in MMX engines.

If using a toothpick to hold in an igniter in a Micro Maxx engine, don't force the toothpick into the nozzle!

Insert the igniter far enough into the nozzle so it touches the propellant. Set a toothpick into the nozzle - don't force it in!

Once slid down the launch rod, the toothpick rests on the blast deflector. The weight of the rocket on the toothpick should be enough to hold the igniter in the nozzle and guarantee ignition.

Semroc Little Joe II Build Paint and Decals

The lower body was painted using WalMart Colorplace Aluminum.
It's one of the better, cheap paints, around $1.00 a can.

Remember those extra trim decals I printed up awhile back? Click HERE for an example of how to make them.

The instructions say: Paint a black band 5/16" wide at the bottom of the main tube. A second band 5/32" wide is painted at the joint between the two wraps.

It'd be much easier just to use some of the black decal stripes printed out earlier. I cut some wider strips to the correct widths.

The strips were cut longer than needed. After drying, they were trimmed down by running a razor blade in the root edge and the overhang strip removed.

After trimming up, here's the lower half of the Little Joe. I'm still debating about adding a spraying on clear coat over the decals.

TIP: Clear coats over a metallic finish will turn a silver paint to a dull gray.

Semroc Little Joe II Build Part 10 Pre-Paint

The fins were glued on and fillets applied.

I tried to pre-plan the fin alignment lines, one was drawn on the lower wrap seam to partially cover it up.

To center the launch lug on the upper wrap:
The upper wrap was marked at the center of it's width with a small pencil tick mark.
The launch lug was marked at it's center.
After a line of glue was applied, I only had to line up the two tick marks.

Tuesday, September 21, 2010

Semroc Little Joe II Build Part 9 Engine Mount Install

The tube is marked for the fins by placing the body tube on top of a marking guide. You are told to mark the fin lines between two of the corrugations.
I found it hard to do this. I ended up just marking the tube as best I could.

Notice the fin alignment line is continued over the edge of the body tube. There is four small tick marks over the back end of the body tube. When the fin is covering the line, having this extension over the back edge of the tube gives another point of alignment.

You can see the inside of the tube edge is darkened. This is CA glue wiped in the body tube ends for extra strength.

The mount is set back 1" inside the tube. It's not hard to apply and smooth a glue fillet to the mount on this lower end.

Applying the upper engine mount fillet from the top of the body tube is another story.
To spread the glue fillet, I used a 1/4" dowel with one end sanded round. Think of it as a long, thin fingertip.
One drop of glue is squirted onto the rounded dowel end. Carefully place the drop of glue down inside the body tube onto the engine mount / body tube joint. Set the glue drop on the joint then spread out and smooth it using the rounded end of the dowel.

When getting the drop of glue down to the joint, try not to get glue on the inside of the body tube. Your target is the centering ring / body tube joint.
You can pick up any excess glue (glue outside the fillet area) with a few passes of the rounded dowel end. Pick up some glue, remove the dowel, wipe it off and go back in to pick up more excess glue.

Internal construction can be as just clean as outside surfaces of the model by taking a few extra minutes to do it right.

Semroc Little Joe II Build Part 7 Body Wraps

I built a little out of order from the instructions. The wraps actually should have been put on before the fins were made.

While the instructions say to use glue to attach the wraps to the body tube, I use spray adhesive so I have a little more time to set them down straight.

In the picture you can see I've already filled the body tube seams, primed and sanded the body tube smooth. A line was drawn down the body tube for the wrap alignment.

The lower wrap was rolled into place without any problems. The match of the ends was very close.

The instructions just say to apply the wider second wrap "close" to the first wrap. I probably put the upper wrap a little too close to the lower one. Not a big deal.

This might lead to some problems with the decal and black band placement later on, we'll see.

Monday, September 20, 2010

Semroc Little Joe II Build Part 6 Fins

Okay - everything was going well up until now.
I was only happy with the way one fin out of four turned out.

I was careful not to use much glue to attach the internal balsa ribs, but I still had distortion. I wasn't too excited about all the edge and joint filling I was faced with. So, I took the easy way out.

No handy balsa was thick enough to cut out replacements, so I laminated two pieces of 3/32" balsa. I simply sanded them to a wedge shape - DONE!

The side surfaces were smoother with no distortion or "pulls" from the glue. I don't know why Estes went with a built up fin on the Little Joe kit. I can understand using built up fins on the Saturn 1B, but on this kit, I found it easier to sand the wedge shape from sheet balsa.

On the left is a "test" fin made from balsa above the one built up fin that turned out well. To the right are the four fins I'll use on the model.

TIP: Here's a tool I find helpful.
I'm holding a Little Joe II fin in a Machinist Square.

The square is at a perfect 90 degree angle. I'll lightly sand the fin sides until the root and trailing edges match the 90 degree angle of the square.

On a four fin model this can help the finished rocket stand on all the fins without wobbling. That is, if the fins are all glued on the body tube equally.

On a three fin model, it doesn't matter. It'll stand on all three trailing edges no matter how badly aligned the fins are.

LAUNCH! Small Stuff - September 20, 2010

I walked to the schoolyard to get a few small launches out of my system.
Four were launched, a few parents walking their kids to school got some early morning entertainment.

The picture to the left is like a cheap advertisement for the Odd'l Rockets line.
That's the BIRDIE with an A10-3t in her tail. I'm using the BLAST! ceramic deflector and RAISE Spring to keep it up an inch or two.

The MMX SKYWRITER downscale was up next. A small 1/2" x 8" streamer has been added with no deployment problems.

The card stock downscale STAR SNOOP GooneyBird got respectable altitude for an MMX engine.

Last up was the downscale CHEROKEE T with a 35 year old MPC 1/2A3-3m engine. Great altitude with a 100 yard walk to pick it up.

TIP: I've been re-using Quest MMX Igniters for some time now.
Maybe my batteries are getting old, but I've yet to burn through one.

This is an MMX Igniter after today's launch, still held by the clips. That's the third time I've used this igniter. I'll keep using it until it breaks or burns through.

Semroc Little Joe II Build Part 5 Fins

Here's the ribs glued into one side of the fin cover.

The instructions are right - use just a little glue to set the ribs in place. Too much and it could distort the other side of the cardstock surface.
Click on the picture for an enlarged view and you can see I tapered the ends for a wedge fit. I didn't want to do a lot of filling later on.

This shows how much of the flat, wider inside rib gets sanded down to match the angle taper of the side ribs.

This is the trailing edge after trimming and sanding to the sides of the fin cover.

Sunday, September 19, 2010

On EBAY, Martian Patrol For Sale!

I don't have a MPC Martian Patrol kit on EBAY.
This is somebody else.
Mine must have came from the same color batch. All the plastic parts were like mine, green fins, yellow nose cone and gray adapter.

You can check out the auction HERE
The Buy It Now price is only $99.95!
Free shipping - What a deal!

If this seller gets half that, mine will be on EBAY tomorrow.
9/21/10 Update:
The kit didn't sell at $99.95 - big surprise. The item has been relisted.