Semroc Saturn 1B - Part 1

Another project I have been meaning to write about was the 1/70 Scale Saturn 1B kit from Semroc we built. I haven't flown it yet, but now that we have the Launch Box working great, we should be good to go on lighting the four motor cluster.



The kit comes nicely packaged in a decent sized box.



It's amazing how much comes out of that box when you start unpacking it. This kit definitely has a lot of parts. I should have expected that... It's a Saturn 1B.



As with all the Semroc kits I have built, the Saturn 1B came with a detailed instructions with check boxes to keep track of your progress. That helps when you have this many steps. The Apollo Capsule was a project in itself. Although included with this kit, the Capsule kit is also available separately.



You have a choice of building a clustered motor mount for four C6-3 motors (600' approx altitude) or a single larger motor mount that will use D12-3 (220' approx altitude) or D15-4 (325' approx altitude).



I chose to go with the four clustered motors. I wanted it to be more like the real rocket and a four motor launch should make for a nice show.





The motor cluster attaches to the stuffer tube that runs up through the center of the model.





This configuration allows for piping the pressurized gases from the ejection charge from the four motors up into the single stuffer tube to deploy the parachute(s).





Four of the eight fuel tubes have to be slotted to fit over the motor mounts.



They are glued in place and also aligned with two "stars."













After you glue on the four slotted fuel tubes, you proceed to glue on the remaining four.



With the tanks glued on, you realize that this is going to be a fairly good sized rocket.





The tail ring is glued into place with spacer strips and fins between the ring and the fuel tubes.



The lower cap ring in glued into place.





The fairing shroud is cutout and glued into place around the bottom of the fuel tubes.



The tank tube cover and tube adapters are glued into place.





The shock cord is attached to the parachute tube which is then clued over the adapter rings.



Shown at this stage of construction next to a Semroc Hydra VII and an Estes Big Daddy.



Another adapter ring is glued onto the parachute tube. The upper body tube is then fit over this and glued. While that dries, you can cut out and glue together the LEM should.



The LEM shroud is glued into place.







Two sets of fin materials are included in the kit. The first set are laser cut balsa wood. The second choice is the "paper of balsa frame" stype which is much more difficult to build. I opted for the framed fins because because they look much better and realistic if finished well.

The following pictures are shots throughout the remainder of the construction.

















To be continued...

Alan's Launch Box

Well, Alan had to do a project at Sonoran Science Academy for the science fair and we needed a new launch controller. So he came up with a good idea and we followed it.


We have been using the small 6 volt Estes controllers for years with no complaints. These handy little controllers are lightweight, are powered by 4 inexpensive AA batteries, have continuity lights, a safety "key" and have never failed us... launching rockets with single motors. The only problem we have ever had with them has been launching rockets with multiple motors. These groups of motors fired at the same time at lift off are referred to as clusters or clustered motors.

We built two Estes 36 D Squared rockets that have been really fun to fly. The problem has been that we have had only about 50-66% success rate using the Estes controller with four AA's.

I had came across a posting online someone who had built his homemade launch controller out of a regular toolbox. It was a very good article and he graciously explained what he had done and the evolution of his box. I will put a link to that article at the end of this entry to give credit where it is due.

I had Alan read the post and start working on his own schematic of what his circuit would look like building a box for 4 launch pads. This was his original drawing.

After his hand drawing he made another version in Microsoft Visio. After we had the basic idea of what we wanted, we headed to the store(s) multiple times. As with most projects like this you don't quite have everything on hand and you learn a lot as you go.

First we picked up a toolbox for about $10 at Wal-Mart and a 3/8" thick piece of good quality wood from Lowe's. We cut the wood with a jigsaw to fit the inside dimensions of the toolbox so that the piece could sit in where the tray would normally go.

Most of the electronic parts came from the local Radio Shack store. We did make multiple trips to Ace Hardware for electrical connectors because the selection was better and they had larger packages. (If they have what you are looking for, Home Depot and Lowe's are usually cheaper for the connectors) The universal automotive starter switch that we use for the Master Safety switch was $9.99 from Pep Boys Auto.


We laid out the board and marked it where we wanted the switches to go. Below is the original layout with the lighted fuse holder near the Master Power Switch. This was later moved to the left of the pad power switches and then later to it's final position up top. This was because of clearance issues with the built in storage trays in the lid. It also shows the Continuity switches which were later removed. We primered and then painted the board with an Aluminum colored paint.


We used regular outlet switches for plugging in the launch cords that run out to the igniters. We used 14 gauge outdoor extension cords that we picked up at Wal-Mart. We also made a couple out of some 16 gauge cords we already had on hand. We bought 50 foot cords and cut them at 35 feet from the male end. We then stripped the remaining 15 foot to harvest the 14 gauge wire for wiring the box inside. This ended up much cheaper than buying bulk 14 or 16 gauge wire. We could get an extension cord and the extra wire we needed for the same price or lower than buying just the bulk wire for the insides..


One thing we did include was a 0-15 Volt DC meter from Radio Shack. They didn't carry it in the local store, but they ordered it for us and it arrived in just a couple days with no shipping cost. It was $12.99. Shown below is soldering the resister for this meter inline and then covering it with heat shrink tubing.


We then wired up most of the circuits to test. We used alligator jumper wires on some paths just for the tests.


After several tests and not liking the tiny wires on the original continuity lights we had installed, we decided to go with some standard size bulbs as recommended for 12 volt launch systems in G. Harry Stines's book. Make sure to use Type 53 bulb for a 12 volt system. (You should use a Type 47 bulb for 6 volt sytems like the Estes controller) We had to make the holes a little bigger, but were very happy with the results.


Once we switched to the larger continuity lights and were able to wire them with 14 gauge as we had with the rest of the box, we finished the connections. We were ready to test some igniters and current readings.





We ran tests with live igniters and quick shorting tests to see what kind of current we were getting from the new system using a 12 volt automotive jump start system as opposed to 6 volts from AA batteries.

All the continuity circuits/lights worked great without lighting the igniters. The igniters fired flawlessly with the launch circuit.



The results were great. We had 1/2 the current on the continuity circuit of the new box as opposed to the Estes controller and more than 5X the current on the launch circuit. The results from Alan's report are below.

Another change we made was eliminating the continuity test buttons from the circuits. It was really unnecessary and just added expense and an extra step to launch procedures. Now if you arm the master and a launch pads power switch the continuity light is already showing whether the circuit is complete or not. If your igniter is connected properly, then you should be getting a green light.

We have had zero failures launching clusters of 2 engines with this new controller. We hope to be testing our Semroc Saturn 1B on four motors and up to the full seven motors on our Semroc Hydra VII here in the near future. We will be sure to report back on how that goes.

Credits: Great idea of using a toolbox, layout and the automotive starter switch from Scott Fintel in his post at http://www.thefintels.com/aer/launchcontroller.htm.

Our final parts list:

1 - Stanley tool box - Wal-Mart
1 - Good quality wood board -Lowe's
1 - 0-15 Volt DC Meter from Radio Shack (22-410)
1 - 12 Volt Car Accessory Outlet - Radio Shack (270-1556)
1 - Universal Automotive starter switch from Pep Boys (85936)
1 - Lighted Fuse Holder - Radio Shack
4 - Continuity Lights - Radio Shack (272-325)
4 - Launch Push Buttons - Radio Shack (275-609)
4 - Lighted Rocker Power Switches - Radio Shack ( 275-712)
4 - 14 Gauge Extension cords - Wal-Mart
2 - Wall Plate Covers - Wal-Mart
2 - Wall Receptacles - Wal-Mart
1 - Black & Decker 12 volt Jump Starter/Air Compressor - Wal-Mart

We also used many connectors and heat shrink tubing from Ace Hardware, Radio Shack, Lowe's and Home Depot. The microclips that we used for our clip whips were also from Radio Shack.

I will do another post later on the quick disconnect clip whips that we made and are using with this launcher.

Back to the blog...

I haven't added any new entries for quite a while, but we have built a lot of rockets and have a lot to write about. We just had another small launch session today that went great.

Danny Pacheco conducted a series of launches for his science project at Sonoran Science Academy - Tucson. He found out some interesting things about drag, stability and performance. He had predicted that his rocket would not fly as high if he made cutouts in the fins because of increased drag. However in his test flights, the rocket flew much straighter and to higher altitudes after cutting the notches in the fins.

We also tested out Alan's new "Launch Box" for the flights today. The primary reason we built the new 12 volt launch ignition system was to ensure smooth, simultaneous ignition of all motors at the same time when flying clustered motors. We had several "no fires" in the past using the small Estes controllers. We have never had any issues using Estes 6 volt controllers for the hundreds of launches we have done with single motors. They are great for that.

However, we have added a growing number of rockets to our fleet that have from 2 to 7 clustered engines. For these we wanted a 12 volt system. We built the new "Launch Box" and it worked fantastic. I will write a separate review of that process and experience later.

Danny with Alan's new "Launch Box"

The flight we conducted with the one of our Estes 36 D Squared was awesome! We launched it on two D12-3 motors for a fantastic tall trail of smoke up into the heavens. Those watching in the park really liked that one!

The 36 D Squared sits next to Danny's experimental rocket as it lifts off Pad #1.

Another big crowd pleaser was the two stage launch of Naomi's Estes Renegade rocket. It was the first flight for this rocket so we flew it on a B6-0 / B6-6 combo and it was excellent. Talk about a happy girl after the perfect liftoff, second stage ignition and flawless separation! Very cool. Expect us to be doing many more multistage launches.




That's about it for now, but I do promise to get back to writing and get some more posts up on building rockets and the new "Launch Box" controller system.

Masters of Doom: Armadillo's roots...

Masters of Doom...

Wow! I finished reading this book by David Kushner a few weeks ago and really meant to get a posting up. It alls ties together for me. Teaching myself computer programming, experimenting with my own rocket engines as a kid, and now having a renewed interest in rocketry myself.

This book brought back many memories from the past. Back to my first kit computer, a Timex-Sinclair ZX81, my Commodore 64 and a luggable IBM PC with little amber screen. I actually carried that thing around with me to class at the University of Arizona...

I started programming games on the TRS 80's and later IBM PC's at Sabio Junior High School. I taught myself BASIC on the ZX81 at home. Later, I fell in love with the Commodore 64. It's added color, resolution and sprites made for much more interesting graphical games.

I wrote some pretty good games, but never sent them off for publishing. Don't we all wish we could go back a change a few things...

I only dreamed of what Carmack and Romero actually did with their games...

Last year at the X Prize Cup Lunar Lander Challenge at Holloman AFB in New Mexico, we actually got to meet John Carmack and watch the flights of the Mod rockets in the competition. We drove over there to see his team complete, visit White Sands and the Space Museum. (Our hotel up in the mountains was even haunted... Very cool.) I will post another entry with pictures from the trip...


Carmack signing the group shot of the Armadillo team that we brought with us.

UA teams up to shoot for Moon!

This is great news for Tucson!

"The UA Lunar and Planetary Laboratory and Aerospace and Mechanical Engineering Department have teamed with Raytheon Missile Systems and Carnegie Mellon University in Pittsburgh to design, build, fly and operate a robotic lunar lander mission.

The team, called Astrobotic Technology Inc., is competing with nine other groups for the the Google Lunar X Prize, which offers a $30 million purse for the first private robotic mission to the moon that meets operational specifications."

Read the full article at: http://www.tucsoncitizen.com/ss/frontpage/78677.php