Mars Snooper Build Part 2 Engine Mount Prep

I've brought this up before.
The end edges of the TA-2050 coupler are cut at a slight angle.
You can see the gap between the coupler and 2050 ring.
With 220 on a block, sand the coupler edge flat.





After sanding, here's the improved fit of the 2050 ring on the flatter edge of the coupler.
You'll just have a slightly wider and better gluing surface.





The original kit had a EB-20A engine block.
These were thinner, lighter black fish paper blocks like a smaller version of the black adapter above.

I didn't have one so I took a newer blue engine block and removed some paper wraps from the inside.

Refinishing the Centurion Part 4

I wanted to add stripes down the body sides like Centurion had in earlier Centuri catalogs.
They were cut from red electrical tape and laid down the body tube. It took a few tries to get them straight. Sight down from the rear of the tube.

For now, the ends were left long. Electrical tape can stretch when applied and I wanted to be sure the tape had shrunk back before cutting off the excess.

In the above picture, a strip of tape was laid down on both sides of one fin.
After it sat for a day, the excess was simply cut near the leading and trailing edges and rolled over the ends.

Here's the re-finished model with a new Semroc decal.
Sure it's a bit heavier than before, but the balsa grain and launch lug seams are pretty much gone.
This was a model worth saving and flying again.

Mars Snooper Build Part 1 Parts

A friend ordered and built the Mars Snooper in the 1970s.
I remember he had trouble with the three shrouds and balsa coolant vanes.
Wish me luck!

Here's all the parts. Some were ordered from Semroc, others I had in my spare parts box. In the lower right corner are the six "pod" nose cones.
I'd already cut the fins out from the templates on JimZ's site.
I'd forgotten how many fins, vanes and strakes were needed.
I printed off three copies of the shrouds onto 110 lb. card stock.
I like having extra shrouds just in case.

Kevlar is shown in the picture, but I might do a Tri-Fold mount.

This is my favorite part needed for construction.

When I was putting parts in my Semroc cart, I searched for the NCW-1 lead weight listed on the Estes instructions.
Semroc had them in stock! I hadn't seen these in a kit for years.
I don't think these new weights were manufactured for model rocketry use. They are a little wider than the inside diameter of the BT-20 it has to fit into. A little filing will get it to the smaller diameter.
There's no center hole for the screw eye attachment.
Still, it's nice to have this part available again.

Refinishing the Centurion Part 3

After fillets and a little sanding, here's the end result.
I wouldn't normally use epoxy on a low power model, but I was happy with the look.

There's a little orange peel in the finish, but that should come out after some rubbing and polishing compound.






This is the upper launch lug with the same thick fillet.





You've got to love an easy mask!

The upper and lower tubes are glued together over the baffle coupler. This point is also the black and white color separation and mask line.
The lower half was masked with clear Scotch tape and then masking tape over a grocery bag.

Refinishing the Centurion Part 2

The nose cone smilies were filled with the CWF mix of 4 parts CWF to 1 part water.

Here it is after sanding to surface.



After sanding the fillet areas, epoxy fillets were added.

The fins were sanded removing some of the original white paint. I didn't go near to the bare wood. I sanded right over the decals figuring the primer would help remove any decal step that might be left.

Look close at the outside edge of the fins and you can see why I wanted to refinish this one. The gray primer really shows off the rough, beaten up edges.

Semroc Defender Finished!

COOL retro model with a three engine cluster!

Lessons learned:
Look and read ahead in the instructions. The decal hitting the upper launch lug could have been avoided by gluing the lug higher up.
If I checked the finishing instructions the payload section would have been painted aluminum before the adapters were glued together.
Double check the wrap on the decals before soaking them in water.
Two of the wraps didn't quite make it around the tubes.
The larger white fins didn't match up to the long white strips as well as I would have liked.
But, I couldn't see any other way to pre-paint and glue it together afterwards.
The old Centuri catalogs say it'll launch up to 3 oz. of payload. Considering there's less than 1/2 oz. of clay, I might fly this with B6-6 and C6-7 engines instead of the recommended B6-4 and C6-5s.

NEW Open Rocket Software Version 1.1.9

The newest version of Open Rocket is now available!
You can find it here:
http://openrocket.sourceforge.net/

If you haven't downloaded this free simulator you are missing out!
While it doesn't have all the features of RockSim it's still a great freebie.
For some Open Rocket tips from an earlier blog post, go HERE

For this version Richard Graham has implemented geodetic computation methods, which take into account the curvature of the Earth, calculates latitude/longitude/altitude and takes into account the coriolis effect. The computation method is selected by the “Geodetic calculations” option in the simulation options. It’s not (yet) a full spherical computation model, but should be accurate enough for pretty much all sub-orbital needs.

Doug Pedrick has also enhanced the printing system with the ability to print fin positioning guides, transition templates and nose cone profiles. Other smaller enhancements and bug fixes are also included.”

Thanks go out to Sampo Niskanen for this great, free program!

Semroc Defender Build Part 23 Decals

The checkerboard roll pattern decal intersected the upper launch lug.
There wasn't enough decal to go around the lug so it was trimmed down on one side.





Whenever I print up custom decals on my ink jet printer, I always print some extra thin trim lines. These were placed where the illustration showed.

The upper checkerboard roll pattern wasn't wide enough to meet around the payload section.





I cut a small rectangle off an old decal sheet and filled in the gap.
I figured one wide square was less noticeable than a gap between the squares.

LAUNCH! Soccer Field November 25, 2011

Black Friday? Forget it. I prefer Black Powder.
I got to the soccer field right around 8:00 a.m.
No wind at ground level, but 100 feet up things were different.

The Semroc BATROK was up with a A3-4t engine. The 13mm engine was friction fitted into an 18 mm casing.
Altitude at ejection was about 350'. First it drifted, then it stayed hung up in a thermal! For a few moments it looked as if it would be out of the field in some body's back yard.
It came down 100 yards away from the launcher just this side of the brick wall.


I'd just refinished the Semroc CENTURION and it was time to add some new flight damage. With the drift from the last launch the rod angle was changed and one of the 12" parachutes was removed. I'll have to catch this one before it hits the ground.

It was slow off the pad (that explains the clarity of the launch picture) and rose to 325' with an Estes B6-4.
Aiming it into the upper winds helped as it came down within 75' of my tripod launcher. I did catch it before it landed in the basketball court.


This is the Custom NOMAD flown with a B6-4.
Lots of drag with the flat nose cone plate but still a respectable 400' altitude.
No damage on recovery under a 12" garbage bag parachute.

Also flown:
FlisKits INTERLOPER had it's seventh flight with a Quest MicroMaxx engine. Altitude was about 85' with streamer ejection while it was still going up.
HotRod Rockets BELLBOTTOM flown with a A3-4t engine. After eleven flights it's always stable, reliable and seemingly indestructible. Altitude was an estimated 350' with streamer recovery.

Semroc Defender Build Part 22 Ends and Edges

Here's how the back end lined up and glue was applied at all motor mount and ST-16 contact points.





The front page of the instructions shows a color rendering of the Defender. It looked black and white to me.
But in step 28, you are told the lower payload section is painted silver.
I would have preferred to paint the tube off the model without masking. I felt it needed a third accent color.




I went with aluminum instead of the suggested silver.
Here's how it looked after the mask was removed.




The Kevlar extended 5" over the top of the main tube. I'll add a few wraps of masking tape to prevent any zippering.

24" of elastic is provided in the kit. But, with three engines and three ejection charges, I'll feel better if the shock cord was longer.
I found a 12" piece of elastic and tied it to the end of the 24" long piece.

The snap swivel hooks were pushed through the knot. This put the two 12" parachutes about 1/3 the way down from the payload section.

Refinishing the Centurion Part 1

My Semroc Centurion has been through a lot! Once it was pulled from a puddle and water poured out of the upper tube.




The forward edges of the fins were chipped and dented.
The nose cone had two "smilies".
Still it was very structurally sound.
I wasn't happy with my first attempt on the build. The fillets were thin, balsa grain showed and for some reason I glued the launch lugs on without filling or painting them.

This model is a favorite. Instead of buying a new one, I thought I'd clean it up and refinish it.
New decals were ordered from Semroc.

Semroc Defender Build Part 21 Assembly

The long strips were slipped underneath the upper body tube section and between the black tubes.

The upper end of the strip goes 1/8" under the upper tube.
Look underneath the lug and you can see the pencil mark at 1/8".


Glue was applied under the lower end of the strip.

Before it set up, the fin can was slipped over just the end of the three tubes.
Here I could check the alignment of the strip end and white fin.
Any adjustments were made before the glue could set up.

A piece of masking tape held the strip in line with the fin.

NEW Odd'l Rockets COMBO KIT!

Remember the Estes MiniBrute Combo Kits?
Here's the new Combo Kit from Odd'l Rockets!
Both a little different and a perfect addition to the Odd'l Rockets line.
Just in time for a Christmas stocking stuffer!

On the left is a Bruce Levison design winner -
The CORKSCREW
That offset ring provides stability, it also makes it corkscrew as it flys!
It's easy to see the spiraling rocket smoke trail before the streamer ejection. Simplicity and fun, all in one model.

On the right is the Powered FLIC SHUTTLE
After many design adjustments and prototypes - stability, strength and reliable performance are guaranteed!

Both models are BT-5 based with streamer recovery and are designed for small field flying. Key area reinforcements were added to both designs for strength and more flights.
Estes 1/2A3-2t and A3-4t engines are recommended for both rockets.

Check with your Odd'l Rockets vendor for Christmas availability!

Semroc Defender Build Part 20 Assembly

Because I didn't follow the instructions I had to make some special considerations before gluing everything together.
For one, alignment of the launch lugs.
The motor mount tubes got a roll of masking tape 1 1/8" from the top. This is how far down the upper body tube will be glued.




After I made sure the lugs were in line, alignment marks were made on the tape.
Another piece of tape was added to the upper body tube for alignment.





When it was slid together and all the tick marks were in place, a glue fillet was added inside. The fillet was placed drop by drop using the rounded back end of a paint brush.

The centering ring isn't really that far down inside, it's just a camera angle illusion.

Dollar Tree Rocket Stuff!

I know, everybody has done a Crayon Bank conversion before - except me.
It was only $1.00, 2 3/8" diameter by just under 24" long.

It should be good to go with a 24mm stuffer tube and through the wall clear fins.



I thought this might make really good streamer material - "No Tear Toilet Paper!"

It's a prank found in the toy section.
Even if it doesn't work at streamer material, I can always leave it in the guest bathroom.

At the Dollar Tree I still buy masking tape, medium CA glue and foam brushes cheaper than anywhere else.

Semroc Defender Build Part 19 Fin Can Mask Part 4

Here's one of the rounded leading edges that didn't turn out as well as the others. It seems there is always one!
This is a simple fix.

TIP: You can take your knife and carefully push the black paint back onto itself!
That is - if the paint hasn't set up. Don't try this tomorrow when the paint isn't malleable.
You aren't cutting or scraping the paint off, just push the overhanging paint line back.




I did have some tearing of the paint line on one fin.
I have been using Rustoleum 2X Painter's Touch brand paint.
It takes touch-ups very well.





TIP: For years I'd spray a bit in the plastic cap and dip the brush in that. But that paint would dry in the cap and make a mess if I had to spray in the cap a second time.

Now I turn over the top of a snack size baggie and press it into a small mixing cup. Spray into the bag and paint!
When you are done, turn the edges up, zip the bag closed and throw it away.
You can use the cup again and again.

Semroc Defender Build Part 18 Fin Can Mask Part 3

Here's the complete mask on the fin can, ready for the black paint.






Before spraying, press down the edge for a better seal.

I've been using a sharpened dowel with good results.
The dowel has a blunt point. I don't want to take a chance and scar the balsa.




TIP: When removing tape, try to pull the tape down and away from the mask line.
If you were to pull straight up, you could get chips and tears.

Semroc Defender Build Part 17 Fin Can Mask Part 2

Instead of completely covering the white fins and body tube with masking tape, I use plastic grocery bags.
Here I've cut a square piece large enough to cover the fin. It's a little smaller than needed to cover the body tube. This last uncovered edge is for the masking tape.






A strip of masking tape is set on one edge of the plastic square -
half on, half off.








The sticky exposed tape is set over the Scotch tape already on the body tube.

Tampa TTRA Launch November 19. 2011

I almost didn't go to the Tampa TTRA launch today.
I had a evening show scheduled and realized the venue was only ten miles from the TTRA site! So, it was a launch in the afternoon then banjos at night.

Lonnie flew the perfect subject for a GoonyBird, an ANGRY BIRD.
When a Goony flys this stable it's a good day at the field.

To the right is my 37 year old MPC MARTIAN PATROL flown with an Estes C6-3.
Both saucers vibrated during boost. At ejection one "hovered" the other flipped end over end.





This is Randy Ejma with an impressive one third scale NIKE SMOKE.
It was a scratch Blue Tube build, flown with a J350 engine.







My Doctor Zooch JUPITER C.
After hitting 650 feet, it was a long walk for recovery. Good thing I only used a B6-4 in this BT-50 based model.







Here's Astron Mike's ECONO GLIDER flown with an Aerotech F21.
Impressive glides are guaranteed with these lightweight foamboard gliders.





This was the best flight of the day, at least from my spectator standpoint.

Gary Horwood reached 3,200 feet with a K700 Gorilla engine in his WASTE-N-TIME rocket.
At ignition there was a big red flame, a thrust buildup and slow liftoff.
I understand this was an experimental engine. This is the way you'd hope all rockets could look at launch.


Also launched:
FlisKits HONEST JOHN with a MMX engine. I was surprised how many had never seen a Micro Maxx engine. I normally have no problem watching a MMX launch, but being this far from the pads I couldn't follow it! Someone did spot the small streamer and with their direction it was found.
Quest STRIKER AGM with an Estes C6-5. Arrow straight vertical flight. Again a walk to pick it up. On the ground the parachute was fully open and dragging the model through the cow pies.
Odd'l Rockets UP! CUP with a C6-3. Odd-Rocs like this fly best in calmer winds. There was a little tip off leaving the rod. It flew 10 degrees off vertical so some altitude was lost. Good flight with the engine ejecting under a streamer.
CD SPOOL with an Estes C6-3. A labored boost was followed by a very fast spinning recovery. No damage on landing.