Adept Rocketry - DDCS2 Instructions and Data Sheet
Dual Deployment™ Controller
Copyright © 1989-2012, All Rights Reserved
DDCS2 Dual Deployment™ Controller
The DDCS2 is a Deployment Controller™. It has two altitude controlled deployment outputs that are typically used to fire deployment charges, based on altitude. The DDCS2 uses the same circuitry as the ALTS2 / ALTS2-50K Altimeter and handles Dual Deployment™, but it does not report maximum altitude after a rocket flight. Because of this, the tedious calibration requirements of the ALTS2 / ALTS2-50K can be avoided somewhat and allow the DDCS2 a substantially lower price. The DDCS2 can be used as the primary deployment controlling device if you don't care about measuring altitude (some rocketeers actually don't). But typically it would be used as a redundancy backup device alongside an ALTS2 / ALTS2-50K (or any other altimeter).
The first charge fires when the rocket reaches its maximum altitude (apogee), and the second charge fires when the rocket descends to 1200 feet or 600 feet or 300 feet above ground (3 choices, user selectable). One common usage is to deploy a main parachute at apogee by using only the first output. However, the most typical usage is to deploy a drogue chute or streamer first, then to deploy a main parachute when the rocket descends to 1200 or 600 or 300 feet above ground (Dual Deployment™), in order to avoid significant drifting due to wind. Dual Deployment™ was invented by Adept Rocketry in 1990 when the term was copyrighted and trade marked. The term Dual Deployment™ remains the sole property of Adept Rocketry.
This device is used in rockets that will reach at least 150 feet altitude. Either or both deployment outputs may be used. The DDCS2 may be used in any rocket configuration including multistage rockets. Individual DDCS2 units may be placed in each stage of interest to handle deployment for that stage. The DDCS2 functions to 35,000 feet above sea level.
The DDCS2 measures 0.9” wide by 0.67” thick by 4” long. It fits inside a tube with a minimum ID of 23.1 mm, or 0.91 inch. It will also fit on either side of a center divider inside a 38 mm ID tube. The device weighs only 25 grams (0.9 ounce), including the battery. It uses a 12-volt alkaline lighter battery with a battery life up to 10 hours, so you need not be concerned about how long your rocket sits on the launchpad after the unit is powered up. The DDCS2 is a totally stand-alone device including the battery holder, the arming mechanism, and the current source for firing deployment charges. Nothing more is required except for the wires (Adept CAB5-xx or CAB5/6-xx series interconnect cable) that connect to the deployment charges and to an On-Off switch.
This altimeter based instrument uses a custom absolute pressure device to precisely measure altitude values up to 35,000 feet in one-foot increments. It uses a logarithmic amplifier along with an 18-bit analog to digital converter to precisely (one-foot resolution) measure the nonlinear pressure versus altitude relationship over this large altitude range. Once powered up, the DDCS2 reports that neither, or one or both deployment charges has continuity. It also constantly measures the ground-level altitude and waits for a quick 150-foot change upward. The first deployment output fires at the very moment when the rocket reaches the maximum altitude. The second output fires when the descending altitude reaches 1200, 600, or 300 feet above the ground (user selectable). Note: the DDCS2 cannot be used for, and will not function for, maximum altitudes less than 150 feet.
CONNECTING THE CABLE AND CHARGES
View the DDCS2 vertically with the five-pin connector at the top and the battery holder toward the bottom. An Adept CAB5-xx or CAB5/6-xx series Interconnect Cable plugs onto the five-pin connector on the upper end.
The deployment charges connect to a CAB5-xx cable as follows. The first charge connects to the ORANGE wire and to the RED wire. This charge will fire when the rocket has reached the maximum altitude (apogee). The second charge connects to the YELLOW wire and also to the RED wire. It will fire when the rocket descends to 1200, 600, or 300 feet above the ground. The RED wire is common to both charges when using a CAB5-xx cable.
On a CAB5/6-xx cable there are two RED wires connected to the center pin of the 5-pin connector. This allows the convenience of connecting a separate RED wire (instead of one common wire) to each charge. A CAB5/6-24 Interconnect Cable is supplied with the DDCS2.
The BLACK wire and BROWN wire connect to an On-Off switch, or some other gimmick for completing a connection between the two wires. A non-elegant but very effective way of making the connection is to simply twist the two wire ends together. Before power up, these wires can simply hang out a hole in the rocket body, such as one of the static ports. After twisting the ends together, fold a piece of masking tape over the exposed ends to electrically insulate them, then push them back inside the rocket body.
TESTING AND USING THE DDCS2
NOTE 1: The precision amplifier circuitry and continuity sensing circuitry on the DDCS2 may be sensitive to noise and static electricity when being held. A 10-second silent time following power up gives time to get your hands off the unit before it starts taking readings. Always handle the device by the edges when testing or installing to avoid touching any of the circuitry. Avoid carpeted floors and other sources of static electricity when handling and testing the device. Never store the device in a clear plastic bag; clear plastic bags are prone to static buildup and discharge. However, pink-colored or smoke-colored antistatic bags are ideal, because they are chemically treated to prevent static buildup. Storage in a small cardboard box, or wrapped in a paper towel inside a clear plastic bag is acceptable. Do not use Velcro to secure the device, as Velcro is a substantial source for unwanted static discharge. The DDCS2 is a super precision instrument. Use care to keep the device clean and dry.
NOTE 2: This device must be installed only in a “clean area.” Electronic Instrumentation is not compatible with the corrosive fumes and residue created by rocket motors and deployment charges. The DDCS2 must be installed in an area that is totally sealed from motors and charges. After passing wires through holes in bulkheads and such, seal them with epoxy or removable putty.
Install a 12-volt alkaline lighter battery (GP-23A, Eveready Energizer No. A23, Radio Shack 23-144, etc.) in the battery holder. The spring end of the battery holder connects to the negative end of the battery. Remove the battery when not in use to avoid prolonged stress on the battery holder and possible long-term disfigurement of the battery holder.
Select 1200, 600, or 300 feet above ground for the second output. While viewing the DDCS2 vertically with the five-pin connector at the top, there is a 3-pin connector at the upper right of the battery holder. To select 300 feet, the lower selection, install a small shorting jumper on the lower two pins. To select 1200 feet, the higher selection, install a small shorting jumper on the upper two pins. These small shorting jumpers may be purchased from Adept Rocketry, or from Radio Shack (Cat. No. 276-1512) if you need some spares. To select 600 feet, do not install the jumper.
To turn the unit on, connect the BLACK wire and the BROWN wire together. Typically these wires will connect to a normally-open On-Off switch or other device. Or the two wires simply may be twisted together. The unit sounds out a long pulsating beep when powered up, to indicate proper operation. Then After ten seconds of silence the unit starts beeping once every 1.6 seconds to indicate that it is now taking altitude readings and is waiting for liftoff. The start up beeps and pause after power up gives the user time to slip the unit inside the rocket tube before it starts looking for liftoff. Also, it is best to wait at least three minutes after power up, and with the DDCS2 inside the rocket before launching. This assures that the precision circuitry has ample time to stabilize and adjust to local conditions.
In actual use in a rocket with live deployment charges connected—do not power up the DDCS2 until it is secure inside the rocket, and the rocket is in a ready to launch position. Note that this indicates that the device should be turned on remotely from the outside of the rocket. Never touch or hold in your hands an active detonating device that has explosive charges connected.
If flashbulbs (or low-current electric matches at a safe distance) are connected (don’t connect anything quite yet), the beeping changes from a single beep to other beeping patterns to indicate continuity of the deployment charges. A single beep every 1.6 seconds indicates proper operation with no deployment charges connected. A double beep indicates continuity of only the first output or first deployment charge, the one that fires at apogee (maximum altitude). A triple beep indicates continuity of only the second output or second deployment charge, the one that fires during descent at 1200, 600, or 300 feet above ground. Four beeps repeating indicates that both Deployment Outputs (both deployment charges) have continuity.
To simulate rocket liftoff it is necessary to pull a vacuum on the altimeter while it is inside a sealed chamber. You need only hold the vacuum for a few seconds, then slowly release. The best method is to put the whole device (including wires and flashbulbs or small light bulbs, for testing the outputs) inside a small wide-mouth juice bottle, and pull a vacuum on the bottle (or you may use an Adept VCK2 Vacuum Chamber—see VCK2 Vacuum Chamber and VCK2 Instructions). It is easy to simulate rocket flights to altitudes of several thousand feet. Slowly pull the vacuum, then slowly release the vacuum. As the vacuum (altitude) increases, the DDCS2 will start beeping at the faster rate of one beep every 0.8 second. This is the indication that 150 feet has been reached (liftoff). If deployment charges are connected to the altimeter, the continuity indicator beeps will stop at this time. The beeps every 0.8 second will continue during the flight until both outputs have fired.
Warning: never install this device in a rocket without first testing its controlling outputs. Always test before each flight. Also, backup deployment systems and/or instrument redundancy (use of two similar systems in the same rocket) are highly recommended.
If an output is not to be used to fire a deployment charge, then leave the two wire ends disconnected. Protect any unused wire ends with tape to keep them electrically insulated. Do not connect unused wires to each other or to anything else.
LIMITED WARRANTY AND DISCLAIMER
Adept Rocketry and Adept Instruments, Inc. warrant to the original purchaser that this product is free of defective parts and workmanship and that it will remain in good working order for a period of 90 days from the date of original purchase. This product will be repaired or replaced within 90 days of purchase if it fails to operate as specified, if returned by the original purchaser and if it has not been damaged or modified, or serviced by anyone other than the manufacturer. Adept Rocketry and Adept Instruments, Inc., their owners, employees, vendors and contractors shall not be liable for any special, incidental, or consequential damages or for loss, damage or expense directly or indirectly arising from customer’s or anyone’s use of or inability to use this device either separately or in combination with other equipment, or for personal injury or loss or destruction of other property, for experiment failure, or for any other cause. This device is sold as an experimental accessory only, and due to the nature of experimental carriers such as rockets, the possibility of failure can never be totally removed. It is up to the user, the experimenter, to use good jugement and safe design practices and to properly pretest the device for its intended performance in the intended vehicle, or reasonable facsimile of same, under controlled conditions to gain reasonable belief that the device and vehicle will perform in a safe manner, and to assure that all reasonable precautions are exercised to prevent injury or damage to anyone or anything.
WARNING: Do not use this device unless you completely understand, agree with, and accept all of the above statements and conditions.
DDCS2 Dual Deployment™ Controller
Additional CAB5/6-24 Interconnect Cable
CAB5-24 Interconnect Cable
Additional GP-23A Alkaline Lighter Battery; Price: $2.25.
GP-23A50 Alkaline Lighter Batteries (box of 50 at 50% Discount); Price: $56.25.
Shorting Jumpers are used to connect two connecter pins together in order to turn on the power for some of the Adept devices. Shorting Jumpers are also used on some devices to program certain values or functions. One jumper is used on the DDCS2 to program the value for the Second Output Function, the output that fires the Deployment Charge for the Main Parachute.
Chamber, Complete with Bottle.
Electronic Instrumentation is not compatible with the corrosive fumes and residue created by rocket motors and deployment charges. Seal holes and gaps in bulkheads and such with epoxy or removable putty.
The perfect mate for the DDCS2 when used in a dual redundancy backup system is the ALTS2 / ALTS2-50K. The ALTS2 / ALTS2-50K would function as the primary device to measure altitude and to control Dual Deployment™. The DDCS2 would function as the redundant backup device to also control Dual Deployment™.
ALTS2 Maximum Altitude Altimeter with
ALTS2-50K Maximum Altitude Altimeter
with Dual Deployment™
NOTES ON MOUNTING AND INSTALLING
The DDCS2 may be installed lengthwise in a small-diameter rocket tube. It will fit lengthwise in a tube with an ID of 24 mm (0.95 inch). It may be mounted in any orientation to plates or bulkheads inside larger diameter tubes. The mounting holes are 0.090 inch diameter for #2 hardware. Use #2 screws, standoffs, and hexnuts when mounting the altimeter to a plate or bulkhead. Do not enlarge the mounting holes, and do not use Velcro. When installing lengthwise, always mount the DDCS2 with the spring end of the battery holder facing upward toward the nose end of the rocket. This will avoid compression of the spring and battery disconnection during a very high acceleration liftoff.
An Altimeter device must be installed in a "sealed" chamber with a vent or vents to the outside. A sealed bulkhead below the altimeter chamber is necessary to avoid the strong vacuum caused by the aft end of a rocket during flight. Any leakage around the motor mount or in other areas at the aft end of the rocket will allow the strong vacuum to be partially felt inside the rocket body. In this case an altimeter could incorrectly indicate an altitude that is far higher than reality.
A sealed bulkhead above the altimeter chamber is necessary to avoid any pressure fluctuations that may be created at the nose end of the rocket. If the front of the payload section slip fits to another section such as a nosecone, then the fit must be as free as possible from turbulence.
A breathing hole or vent (also known as a static port) to the outside of the rocket must be in an area where there are no obstacles above it that can cause turbulent air flow over the vent hole. Do not allow screws, ornamental objects, or anything that protrudes out from the rocket body to be in line with and forward of a vent hole. The vent must be neat and burr free and on an outside surface that is smooth and vertical where airflow is smooth without turbulence.
Some rocketeers use multiple static ports (vent holes) instead of just one. Very strong wind blowing directly on a single static port may affect an altimeter. Multiple ports evenly spaced around the rocket tube may help cancel the effects of strong wind on the ground, the effects of transitioning through wind shears during flight, the pressure effects of a non-stable liftoff, or the pressure effects that occur due to flipping and spinning after deployment. If you wish to use multiple ports, then use three or four. Never use two. Ports must be the same size and evenly spaced in line around the tube.
The general guideline for choosing port size is to use one 1/4 inch diameter vent hole (or equivalent area, if multiple holes are used) per 100 cubic inches of volume in the altimeter chamber. For instance, An eight-inch long four-inch diameter tube has a volume of about 100 cubic inches. Use one 1/4 inch port, or three or four 1/8 inch ports evenly spaced around the tube. An altimeter chamber two inches in diameter and eight inches long (25 cubic inches) needs one 1/8 inch vent hole or three or four 1/16 inch vent holes. Try to keep hole sizes within -50% or +100% of the general guideline. Do not make the holes too small, and especially do not make them too large. Obviously, a vent or vents in a small body tube (18 mm BT-20 or 24 mm BT-50) will be quite small. However, in general, the vent holes need never be smaller than 1/32 inch. Also, the vent hole diameter need never be less than the thickness of the body tube.
Adept Rocketry completed the research on static port sizes in 1990. The information provided here has remained the industry standard ever since those early years.
When possible, vent holes should be a minimum of four body diameters below the junction of the nosecone with the rocket body. This is necessary with high performance (high speed) rockets. The tremendous pressure on the nosecone leeches down the rocket body as much as three or four body diameters before it dissipates. However, with lower speed rockets, the "minimum of four body diameters" rule may be reduced to one or two.