The New WLCS-2
Those of you who attended NARAM 61 in Muncie, Indiana may remember that we started the event with our newly developed wireless launch control system. That system was designed and built specifically for NARAM to make it easier to maintain the range for the week. While the system worked well on the test bench, using it on the range was a different story. As the sun beat down on the system (and the asphalt it was sitting on) the internal temperature raised far beyond the design limits. Before long the system failed spectacularly. ROCI swapped the system with our older, wired system and a good time was had by all of the attendees. On the other hand, I found myself knee-deep in problems that I had to identify and correct in order to make the wireless system work.
After tearing into the system to evaluate what caused the failure I came to the conclusion that the design was basically sound but required a little tweaking. The weak link in the original design was the surface-mounted MOSFET selected to switch igniter current on and off. This component just couldn't handle the temperatures we encountered. There were two ways to solve the problem: 1) use MOSFETS that could handle higher temperatures, and 2) add a cooling fan to the system. I chose to do both. The new system debuted at a ROCI launch later in the year and it worked very well. In fact, it has become ROCI's primary launch system.
Fast forward two years... The system has now been used at the club's monthly launches throughout this period and has been mostly reliable. We have gathered information about system errors and shortcomings over that time and I have addressed most of these concerns with software patches. After getting the problem under control I started looking at missing features. One of the most requested features was having the ability to select more than one pad to allow drag racing. While I don't personally do drag racing, the feature was requested enough that I decided to have a look at it. Adding it ended up requiring a fundamental change to the system firmware that cascaded into other improvements. The end result is Wireless Launch Control System 2 (WLCS-2).
The feature list for WLCS-2 is being completed at this time. Please check back for updates.
The new WLCS-2 system is progressing well toward completion. Operating information will be presented here when the system is completed and ready for use.
Check back from time to time for updates.
Wireless Launchers; The Next Step?
Model rocketry started in the early 1950s as a form of space-age entertainment and has become a popular hobby among children and adults alike. Model rockets are launched for various reasons, such as competitive events, educational purposes, and just for fun. They are usually constructed out of paper, plastic, or wood. Model rockets can easily reach altitudes in excess of 500 meters before deploying a parachute and returning safely to Earth to be prepared to be launched again.
Early rockets used a fuse to ignite the propellant. This method of ignition lead to many hobbyists being injured or burned so, in the early 1960s, an electric-powered model rocket launch controller was introduced. This new system provided a safer launching experience and was quickly adopted by modelers around the world.
As the popularity of model rocketry grew launch events began to get larger. These larger events lead to the development of a more complex, multi-pad launch system with a central control console. Launchpads were connected to the launch controller with a series of cables and were selectable so that only one rocket was launched at a time. This system is essentially what the model rocketry hobby has used since it was introduced.
With the adoption of more powerful engines and larger airframes, it became necessary for spectators and participants to be farther from the launch pads when rockets are launched. These distances have caused a number of disadvantages for the currently used wired systems. The primary problem is the long interconnecting cables. These cables cost a lot of money, present a tripping hazard when run along the ground, and dissipate a large amount of current requiring remote relays at the launch pads.
Cables are a pain to set up and tear down and they can really get in the way when stretched between the controller and the launch pads. Faulty wiring, lost cables, and complicated setup are all common issues when setting up a wired launch range. That's why we need a better solution that will eliminate these problems once and for all.
WLCS - Wireless Launch Control System is the answer. WLCS is an innovative cordless system designed to eliminate all of these problems. It eliminates the cables, eliminates the clutter, speeds setup, and teardown while also providing enhanced data from the rocket, and providing better control for up to 180 launch pads. It takes only minutes to set up and tear down the system and each device is built into its own carrying case for easy handling and storage.
As most of you know, I've been working on a new version of the wireless launch system. The original plan was to rebuild the existing system over the winter and have it ready for Spring. Well, that kind of allowed the possibility that Spring would come and we wouldn't have a functional launch system -- not good! So I decided to do things a bit differently. I'm currently finishing up 2 smaller systems. These systems consist of a launch controller and two pad controllers. This setup will allow me to test all of the functionality of the system design without disabling the club launcher. When all of the tests are complete I will start on the club system.
I'd like to stress here that all of the parts for the two test systems have been paid for by me. No club funds have been used on them. These are my test systems for future changes but we may use them from time to time at club launches to test changes before they are applied to the club system. In many cases, the only thing that will need to be done is to load a software update into the club's launch system but not for the current changes. All of the guts of the current boxes will be rebuilt reusing as many of the existing components as possible. This will be a large task that I could use some help with when the time comes. One item that will need to be purchased for the club system update will be the touch screen for the launch panel. The new touch screen is sunlight readable and higher resolution. It was also more expensive. The touch panel for the upgrade will cost the club $120 by the time shipping and taxes are added. I recommend that the club purchase 2 of them so there will be a spare in the event of a failure.
So, what's different about the new system? A lot! Physically, all of the electronics are now built onto a single panel. This makes maintenance much easier since everything is in one place for testing. The batteries are now strapped into a battery holder so they no longer flop around. Only one connector is mounted to the exterior of the box; the charge connector. This connector has been changed to make it very difficult to connect incorrectly. I would say it's impossible to do but then someone would try to prove me wrong.
Summary of physical changes:
- New, sturdier, mounting adapter for the cases.
- New battery mount.
- Improved panel layout.
- Elimination of most external connectors and controls.
- Much improved touch screen with a sunlight-readable display.
- Smaller igniter lead connectors (XT30 vs XT60)
- New printed circuit board with a variety of improvements
Summary of operational changes
- New pairing operation that ties launchpad controllers to a specific launch controller (and vice-versa) to ensure that only your launch controller can command a launch (or any other operation)
- New setup screen to allow the launch controller to be configured. Pairing is entered from this menu (a pairing switch is provided on the launchpad controller). Also on the setup menu is the ability to scan the range to rebuild the pad list, the ability to do a switch test, set a custom System ID (required), and reset the system to 'factory' settings.
- The banks are still selected using the key switch as before. Selecting a bank automatically selects the first group associated with the bank and displays the launchpad status of all pads.
- Pads are displayed with their associated continuity. Touching a pad button will toggle its state. in 'ADD' mode, more than one pad can be selected in the same manner and all will be armed and launched when directed to do so. Pads cannot be selected if they have no continuity.
- Every operational command sent to the launchpad controllers will return the continuity for all of the pads. This is done in the command acknowledgment so it no longer requires a series of continuity requests to update this status.
- The available groups are always displayed at the bottom of the screen in all operational modes.
- 'Keep Alive' functionality has been added. The launch controller will periodically send 'pings' to the launchpad controllers to ensure they are still responding to commands. If a group fails to respond it is removed from the available group list. Additionally, if a paired device is turned on after the range is set up, the 'ping' command will discover it and add it to the available group list.
- Color coding on the screen controls has been more standardized. Gray indicates that the control is not selectable. Yellow indicates the item is in a 'caution' state. Red indicates the item is in an 'armed' or' ready to fire' state.
- Hand-shaking has been improved.
The new system will be tested at the May launch. The existing system will remain unchanged so it can be used for our main activities.