Thursday, June 30, 2011

ASP Micro Wac Corporal Build Part 8 Paint - Oops!

When spraying, I'll apply light colors first, masking, then spray the darker colors.
Three colors are used, yellow black and silver.
My plan was to use gray primer and sand.
Then white primer and very light sanding.
On the upper Wac section, yellow was sprayed overall. In the first picture, I've masked for the silver fins.

I should have masked for the black areas and followed with the silver last.

The silver looked okay before I put tape over the fins to mask them out for the final black.

This picture was taken after the tape was removed off the silver fins. The sticky side of the tape had ruined the smooth silver surface. I would have gotten better results with a brush!

Even though I gave the silver adequate drying time, the tape still ruined the painted surface. Silver paint is always iffy.

TIP: Avoid using masking tapes on silver paint!
Note to self: Try to make silver the last color you lay down.

I had to sand the fins smooth and mask over the black this time.
The fins look terrible in this picture, you can see silver, yellow and primer when all was sanded down. They are actually smoother than they look!

Case in point:
I was looking over the instructions for the Quest AS-1 Escort kit.
In Step 26, you are told to first spray the rear of the model black, concentrating on the tail and rudder fins. The tail and rudder fins are black on the face card picture.
In Step 27 you mask off the black tail and rudders and spray the rest of the model silver!
Normally, you'd think the black (or darkest color) would go on last. Not so here! Quest doesn't explain the reasons why (you should spray silver over the black) but it's obviously to avoid using masking tape on silver paint.

George Gassaway's Seam Filling Technique Applied

Oh boy - another Saturn V!
Actually, I'm building two Apogee Saturn Vs for a customer.
In quality and size, this Saturn is a big step up from the Estes kit.

Recently, I've been using the seam filling technique suggested by George Gassaway where you direct the primer/filler into a narrow strip directly on the recessed seam. You can read about the technique HERE.
When I tried this technique before, I used Carpenter's Wood Filler and sanded smooth. I then masked, as shown below, and used a spray primer. This time I'm using just the spray primer.

The seams on the Apogee Saturn V tubes were a little wider than normal but not deep enough to hold the Carpenter's Wood Filler. The CWF would chip and fall out of the seam when sanding.
This would be the perfect test model for George's method.
This is a big model, over five feet tall and 5.66" in diameter. Normally it would take a lot of primer and sanding.

I masked off 1/16" to the side of the seams with masking tape. In between the masking tape, long paper strips were taped down.

I've been using Dupli-Coat automotive filler primer after reading a recommendation on TRF. It's got one of those fancy nozzles. You can turn the tip for a wide spray or a thinner line. I turned the nozzle tip 90 degrees for the thin line spray. This way I could direct the spray right at the seams.

It was sprayed on two coats, fairly thick. I didn't sand it down between coats. I wanted to build up the primer before sanding. I didn't want to take the time to spray, remove the tape, sand then reapply another mask to spray again.

After the two thick coats, here's what it looked like once the entire mask was removed. You can really feel the raised primer "stepped" over seam.

Here's the tube area after sanding.
It took much less primer, sandpaper and time to get the seam filled by not spraying primer over the entire surface.
One of the purposes of the primer is to show imperfections such as glue and rough spots. These can be then cleaned up before the final color coats. Primer seals the surface and gives the final colors a better grab on the surface.
Granted, I'll spray a lighter coat of primer overall before the white base.

Wednesday, June 29, 2011

LAUNCH! Schoolyard, June 28, 2011

Central Florida had big rain yesterday, the skies were still overcast. My launcher was set up by 8:00 a.m. before the winds came up.

Here's my carded downscale A-20 DEMON launched with an Estes A3-4t engine. Free plans are available, check the "Free PDF Plans" tab on the blog.
This one gets great altitude with a BT-20 based body. I would guess the altitude was around 400' with streamer recovery.

The Eric Truax carded SCAMP flew to 250' with an Estes A8-3 engine. The overcast sky made the engine flame look big. It recovered under a homemade 12" diameter garbage bag parachute.

This is a favorite in the fleet, bigger than most carded models. It's a full size BT-50 sized rocket. Enlarge the picture and you can see the nose cone is rolled in stepped segments.

My big launch of the day (for this small field anyway) was my Semroc CENTURION with an Estes B6-4.
In this small field, a B engine in a BT-20 based rocket would probably be lost. But, in this bigger demo bird it seems to be a good match. Altitude was 325'.

While the kit is supplied with two 12" parachutes, one was removed to keep drift to a minimum.

Also flown:
The FlisKits MMX HONEST JOHN with a Quest MicroMaxx engine. Clean straight flight with streamer recovery.
The 13mm Odd'l Rockets UP! CUP with an Estes A10-3t engine. A noisy wiggler with aerobrake recovery.

TRF Forum Bully?

Before I go on, I should clarify something about the building techniques I use.
Here's a condensed version of what I wrote in the first blog post, almost one year ago:

"Everyone has their own "proven" ways to build rockets. This blog is not to say I know all the right techniques. It's what works for me, but I'm always open for a better way to get it done. Who knows? Someone might pick up a new technique or be inspired to improve on what's written here."

Before the Internet, most developed building techniques on their own through trial and error. We'd pick up a tip here and there, usually from the yellow pages (technical section of the Estes catalog) or the Model Rocket News.

If you'd like to see a lively discussion, go to The Rocketry Forum. Scroll down to the "Techniques" section and read the posts under "Water Decal Solutions."

This isn't the first time Mr. McCoy has gone out of his way to tell me I'm wrong.
I heard about it when I painted my Fliskits MMX Honest John like my old Estes HoJo scheme.
I wasn't trying to build a true scale model, just a tribute to the Estes Honest John, the way their instructions and decal sheet showed.

When I scratch built MicroMaxx motor mounts from card stock I was told they were too heavy and I should be buying commercially made mounts.
That small amount of extra weight wouldn't matter anyway, every cardboard and balsa MicroMaxx I've flown has ejected before reaching apogee.

Once he implied I wasn't being professional.
I corrected him saying: "I IS a professional." I actually make some (okay, a little) money making model rockets.

Yesterday, Mr. McCoy jumped on me for adding a small drop of dish detergent to a water bowl for soaking decals.
I've done it this way since getting back into the hobby. No problems, no lifted decals. Heck, I don't clear coat or use Future over decals.
To quote Mr. McCoy: "It's the BETTER end results that will be obtained by NOT doing something frankly stupid that needs to be encouraged."
So now I'm stupid?

I don't get it. A forum bully?
Mr. McCoy, lighten up. It's a hobby, for Pete's sake.

Tuesday, June 28, 2011

Vern Estes Motor Patent

Here's a patent illustration for the Estes model rocket motor.

There has been an argument regarding whether it should be called a engine or a motor. On this patent it is called a "Toy Rocket Motor".

This patent was filed July 24, 1959 and approved March 24, 1964.
I don't quite understand the Figure 1 drawing. It looks more like a bottle rocket. Maybe it was to show a comparison between a fireworks bottle rocket and a model rocket.All drawn engines look to have a fuse in their nozzles.

Take a look at this early Carlisle patent.

In Figure 5: While it looks like a model rocket motor, there is a fuse outside the motor casing acting as a delay. It runs from the top of the propellant to the ejection charge.

From what I've read, some of the RDC (Irv Wait) engines had a fuse outside of the casing. The length of the fuse determined how long the delay was before ejection.

ASP Micro Wac Corporal Build Part 7 Tunnel

The thicker half round is cut to 2 1/4" long.
Both ends are tapered as shown.

It is glued 1/2" from the top of the upper tube.
This half round tunnel is already contoured to fit the curvature of the body tube!
I ran CA fillets down the seam like before with the fins.
The fillets were sanded smooth with 400 grit.

Monday, June 27, 2011

ASP Micro Wac Corporal Build Part 6 Gluing Fins

After the fins are lightly tacked in place, they are checked from the rear for correct spacing.
A CA fillet is applied with a toothpick tip.
Place a drop of CA on scrap paper. Dip the toothpick in the drop.
Drag that drop down the root edge joint making a fillet.

It might take two or three applications to build up a fillet or fill a gap. Any extra glue can be sanded down with 400 grit sandpaper.

It'd be a good idea to join the upper and lower sections together when gluing on the fins. This way you are assured the upper and lower fins are in line. Use that leftover half coupler to hold both sides together.

TIP: The instructions say to cut the lug and standoff in two and glue that to the body tubes. I decided to save a few steps and glue the lug to the standoff, then cut the longer glued assembly in two.
This way I could sand the ends of the lug and standoff flush with each other off the main body tubes.

All the fins and lugs are in place and in line with each other.

ASP Micro Wac Corporal Build Part 5 Gluing Fins

My build is a little out of sequence with the instructions.
This kit has the smallest fin marking guide I've ever seen.
Like other larger models, it's wrapped around the tube and the fin and lug locations are marked.

The kit includes a small plastic angle for extending the fin lines down the body tube.
It's a nice extra, the tube is too small for a door frame or larger aluminum angle.

I found it easier to use medium CA glue to place the fins.
A small drop was place on the back side of scrap sandpaper. The fin root edge was run through the drop.
This is a much easier way to get a small amount of glue on the root edge as opposed to applying it right from the CA bottle.

I don't want a lot of glue on the edge, the fins are small and hard to place straight on the small tube. With a little bit of glue, you could remove it if the placement is wrong the first time.
After you are certain the position is straight, you'll add a glue fillet in the next post.

Sunday, June 26, 2011

Nose Weight Comparison

Two years back I entered the EMRR Box O' Parts Contest.
I received a box full of spare parts and a few rocketry memories - a few things I hadn't seen for years.

One find was an old Estes lead nose cone weight, seen on the left.
This was the same style of weight I first saw in a Estes Wac Corporal kit. The outside diameter is 11/16" and fits inside a BT-20 body tube. In the 1969 catalog it was #651-NCW-1 and sold three for a quarter.

You can't get these lead weights anymore, I was curious to see how the available Semroc washer weights compared.
On my cheap scale, the Estes lead weight was 0.14 oz.
(this was slightly heavier than the catalog weight of 0.12 oz.)
It took three Semroc washer weights to get close at 0.15 oz!

ASP Micro Wac Corporal Build Part 4 Nose Weight

The Kevlar lead weight is tied to the split weight.
The weight is crimped around the line.

The half coupler holds the weight at the top of the upper body tube, beneath the nose cone shoulder.

With the coupler, weight and Kevlar in position, the base of the nose cone is inserted and pushes the weight into the correct position in the tube.
Pull the nose cone out, and apply glue to the weight and inside tube.

Saturday, June 25, 2011

LAUNCH! Schoolyard June 24, 2011

Even though the build is still ongoing, the ASP WAC CORPORAL is actually finished. I was anxious to fly it.
This morning about 7:30 a.m. it did with a MicroMaxx engine.
Straight as an arrow up to about 75 feet.
The mylar streamer did deploy without problem and no melting. The inset picture shows I stuck the nose cone on landing.
There was only a bit of ejection soot in the clear tube above the engine. Most of it was cleaned out with a trimmed Q-Tip.

My CORKSCREW wiggled it's way up to 350' with a A10-3t engine. I had a rare eject of the friction fit engine, but the streamer did eject.

A Quest A6-4 engine had a throaty roar compared to the other Estes engines launched today.
Again my Semroc ASTRON had a wiggle off the launch rod and was off vertical during thrust.
At an estimated 300' up, the reefed parachute ejected fine and the five MPH wind brought it back close to my tripod launcher.

Last up was my indestructible CHEROKEE T carded downscale with an MPC 1/2A3-5t. I'd estimate the altitude at 425 feet. This is one of those rockets you can't bend, dent or lose. It just keeps showing up in my launch box.

Also Flown:
The Micro GALAXY GUPPY with a MMX engine. Good flight with nose blow recovery.

ASP Micro Wac Corporal Build Part 3 Fin shaping

The coupler is cut in two. You'll only use 1/2 of the coupler in the build.
The fins were gang sanded to be sure they were all the same size.

This is all three of the upper fins on a sanding block.
The Wac Corporal fins are slightly rounded on the outside corners.
I rounded all three fin corners at one time for consistency.
Be careful, it's easy to take too much off - I did.

Here's six lower and upper stage fins after shaping and rounding.

Friday, June 24, 2011

ASP Micro Wac Corporal Build Part 2 Fins

The nose cone was a little tight in the upper tube. It needed a little sanding for a better fit.

I took a few minutes to true it up, the sharp tip was a little out of round. No fault of ASP, turning nose cones this small is difficult. All the parts are of high quality.

The instructions recommend cutting out the fin pattern and tape it to the flat styrene using double sided tape. I extended the fin outlines on the instruction sheet and taped the styrene to the instructions.

I didn't try to cut all the way through the styrene. I went about half way through and removed it from the instruction sheet.
The pieces were cut the rest of the way through with my knife and straightedge.

The body tubes had a very small spiral seam. It was filled thinned wood filler and sanded smooth.
The nose cone got two coats of sanding sealer and was sanded smooth.

Estes Saturn V Specs and Pics

Andrew B. emailed me about my build and asked for some Saturn V finished specs.
Here's my stock build measures up next to the Estes numbers from the box spec card:

Estes finished weight: 11.0 oz. (empty, no engine or wadding)

My build finish weight: 11.53 oz. (empty, no engine or wadding)
My build flying weight: 13.21 (D12-3 engine and eight squares of Estes wadding installed)

My center of gravity (loaded for flight balance point) is 15 1/8" from the rear.

The height of my Saturn V build is the same as the Estes kit spec. at 43.25" tall.

Remember, I added a Monokote trim piece around the service module tube. This shouldn't be much heavier than a coat of silver paint. I probably build heavier and use a little more spray paint than the average builder would.
In the 1974 Centuri Catalog, their Saturn V (close to this reissue) weighed in at 9.2 oz.
In the 1974 Estes Catalog, their Saturn V weighed in at 9.9 oz.
In the same 1974 Estes catalog, the maximum lift-off weight for a D12-3 engine is 14 oz. So my Saturn, weighing in at 11.53 oz., should be fine with a D12-3 engine.
That is - if I ever get the nerve to fly it!

Parting shots:

High end and low end!

Thursday, June 23, 2011

ASP Micro Wac Corporal Build Part 1 Parts

This is one of the three MicroMaxx kits I bought in a lot on EBAY.
Here's all the parts:

Like the ASP Micro Jayhawk, there is no balsa in the kit. The nose cone is hardwood and all fin and details are white styrene plastic.

The top half is the Wac Corporal that most are familiar with. This model has a Tiny Tim booster. It is a single stage MMX powered kit. At ejection, the separation point is between the two stages.
Note the clear plastic tube. That simulates the open area between the two stages and gives support to the thin half round supports.
The mylar streamer is optional, the instructions state it'll aid in visibility.

Here's some kit pieces of interest:
The lead shot nose weight is in the middle of a long piece of Kevlar.
The bigger half round piece will be the tunnel.
The very skinny half round piece will be the supports between the stages.
You'll only use half of the brown coupler. It holds the weight high in the upper body, right beneath the nose cone shoulder.
The double stripe in the decals help with the color separation and when placed give the correct spacing of the black bands.

S.D. Xanadune Build FINISHED!

This model was a great break after the Saturn V build.
I was ready for something different and this certainly fit the bill.

I have to give credit to whomever the designer was. There are a few great innovations but other ideas fall short.

  • The laser cut parts fit together very well, but the burns weren't clean.
  • The integrated baffle/centering ring assembly was interesting. (The instructions still call for a single square of wadding on top of the baffle.)
  • The round shock cord seems stiff and too short for the model.
  • The provided parachute shroud lines were half the length they should have been.
  • The engine lock ring is new to me and works well.
  • There is very little room for the parachute.
  • I can't quite figure out the reasoning behind the "nasal strip" tape strips and plywood reinforcements.
  • Angled spin fins. The wood grain wasn't parallel to the leading edge.

    Still, a welcome change from the ordinary.
    That silver and gold paint is already showing fingerprints!

    I look forward to seeing how well it flys!

  • Followup: The first flight wasn't successful. While the boost was spinning and straight, most of the ejection charge blew out the back side of the square engine mount! The nose cone dislodged, but the parachute stayed inside. The parachute had a small melt, even with the baffle and a recommended square of wadding.
    The flight report with pictures is HERE

    Wednesday, June 22, 2011

    S.D. Xanadune Build Part 12 Assembly

    The parachute was tied to a snap swivel.
    Again, note the short shroud lines.

    The snap swivel was attached to the shock cord a few inches down from the nose cone attachment lug.

    Here's a picture of the the engine lock ring holding an engine in place.

    This picture was taken before all the fin trim lines were on.
    A pretty interesting way to lock in the engine. It fits well and cannot be shaken loose.

    S.D. Xanadune Build Part 11 Trim Stripes

    1/16" wide strips were cut from the Contact paper for trim.
    (I should mention the while the Contact paper is called a "paper" it's actually a thin vinyl. )
    I wanted to have angled trim strips going around the nose cone and lower engine mount bodies.
    The only problem, the vinyl strips won't lay flat around the corners.

    I ended up using the small scissors on my Swiss Army Knife to cut the corners apart.

    The pieces were individually removed and slight angles trimmed on an area of the backing sheet.

    Tuesday, June 21, 2011

    Saturn Towers

    I've built a lot of towers over the years.
    For comparison, here's the Saturn towers from various kits.

    On the upper left is the BT-20 based Dr. Zooch Saturn V tower. It's really a silhouette tower, made of four sided card stock. Still, very strong and effective at this size.
    In the middle is another Dr. Zooch tower make of dowel and wire from the Saturn 1B series of kits.
    To the right is the Estes 1/100 scale capsule and tower from the recent, reissued Saturn V kit.

    The silver capsule to the left is the Semroc Little Joe II kit. 1/70th scale, it's constructed from dowels.
    And finally, the Apogee Saturn V tower. This picture was taken while the model was still under construction.
    Both the final two builds are 1/70th scale. Compare the two towers. The Apogee Saturn is closer to the truth in strut diameters!