Adept Rocketry - DDCS25 Instructions and Data SheetDDCS25 Dual Deployment Controller™ Two Versions:DDCS25 functions to 60,000 ft. DDCS25-100K functions to 100,000 ft.
Copyright © 1990-2008, All Rights Reserved DESCRIPTION The DDCS25 Dual Deployment Controller™ is
based on the ALTS25 Maximum Altitude Altimeter with Dual Deployment™.
It is the same as the ALTS25 in all its functions except that it does
not report altitude. It is less precisely calibrated than the ALTS25 and
is therefore lower in price. One of its primary uses is as a redundant
backup for the ALTS25 (they both fly in the same vehicle). Or the DDCS25
may be used as a primary device to control Dual Deployment™ in a
flight when the actual altitude attained is not important. The DDCS25
has two altitude controlled deployment switches that are typically used
to fire deployment charges, based on altitude. The first charge fires
when the rocket reaches its maximum altitude (apogee), and the second
charge fires when the rocket descends to 1,800, 1,200, 900, 600 or 300
feet above ground, or two seconds after apogee, or at 150 feet below
apogee (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 a user selected altitude
above ground (Dual Deployment™), in order to avoid significant
drifting due to wind.
This device is used in rockets that will reach at least 300 feet
altitude. Either or both deployment switches may be used. The DDCS25 may
be used in any rocket configuration including multistage rockets, in
which case the deployment control for a particular stage can be handled
by placing the device in the particular stage of interest. Or individual
DDCS25 units (or other altimeter devices) may be placed in each stage of
interest to handle deployment for each stage. The DDCS25 functions to a
maximum of 60,000 feet above sea level. The DDCS25-100K is an extended
version that functions to 100,000 feet.
The DDCS25 measures 1.4” wide by .6” thick by 3” long. It fits
inside a tube with a minimum ID of 1.5” (38 mm). It will also fit on
either side of a center divider inside a 54 mm ID bay 3” long. The
device weighs only 1 ounce, including the battery. It uses a 12-volt
alkaline lighter battery with a battery life up to 6 hours, so you need
not be concerned about how long your rocket sits on the launchpad after
the unit is powered up. The DDCS25 is a totally stand-alone device
including the battery holder, arming mechanism, and current source for
firing deployment charges. Nothing more is required except for the wires
(interconnect cable) that connect to the On-Off switch and to the
deployment charges.
The altimeter device uses a custom absolute pressure device to
precisely measure altitude values up to 100,000 feet in one-foot
increments. It uses a 17-bit logarithmic 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 DDCS25 reports that neither, or one or both deployment charges has
continuity. It also constantly measures the ground-level altitude and
waits for a quick 300-foot change upward. The first deployment switch
fires at the very moment when the rocket reaches the maximum altitude.
The second switch fires when the descending altitude reaches either
1,800, 1,200, 900, 600 or 300 feet above the ground, (or two seconds
after apogee, or 150 feet below apogee) as preset by the user. Note: the
DDCS25 cannot be used for, and will not function for, maximum altitudes
less than 300 feet. SPECIFICATIONS
TESTING AND USING THE DDCS25 NOTE 1: The precision amplifier circuitry and
continuity sensing circuitry on the DDCS25 may be sensitive to noise and
static 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; however, pink-colored or
smoke-colored antistatic bags are ideal. Storage in a small cardboard
box, or wrapped in a paper towel inside a plastic bag is acceptable. Do
not use Velcro to secure the device. Use care to keep the device
clean and dry.
NOTE 2: Install in a “clean area.” Electronic
Instrumentation is not compatible with fumes and residue created by
rocket motors and deployment charges. The DDCS25 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.
Connect an Adept CAB6L-xx series interconnect cable to the 6-pin
connector on the DDCS25.
The BLACK and BROWN wires enable power to the altimeter device when
they are connected together. They may be connected to an On-Off switch.
The RED and ORANGE wires connect to the first deployment charge, the
one that fires at apogee.
The YELLOW and GREEN wires connect to the second deployment charge,
the one that fires during descent as selected by the user.
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. After ten seconds of silence the unit starts beeping
once a second to indicate that it is now taking altitude readings and is
waiting for liftoff.
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 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 as selected by the user. Four beeps repeating indicates that
both deployment charges have continuity. SETTING THE SECOND OUTPUT VALUE When viewing the front of the DDCS25 (with the
cable connector at the top, and the battery holder near the bottom), a
four-pin square connector is located below the right end of the battery
holder. When no jumpers are installed on the connector, the default
altitude setting is 600 feet above ground. The second deployment charge
will fire during descent at 600 feet. When a single shorting jumper
(Radio Shack Cat. No. 276-1512 or equivalent) is installed horizontally
on the lower two pins only, the setting is 300 feet. When a single
jumper is installed horizontally on the upper two pins only, the setting
is 900 feet. When two jumpers are installed horizontally, on both the
lower two pins, and on the upper two pins, the setting is 1,200 feet.
Jumpers also may be installed vertically on the four-pin square
connector. When a single jumper is installed vertically on the left two
pins only, the setting is 1,800 feet above ground. The second deployment
charge will fire during descent at 1,800 feet.
When a single jumper is installed vertically on the right two pins
only, the second deployment charge will fire two seconds after apogee
(two seconds after the first charge fires). With this setting it is
possible to use the second output as a backup for the first charge. With
this setting it is possible to create an apogee deployment sequence that
is implemented with two timed steps.
When two jumpers are installed vertically, on both the left two pins,
and on the two right pins, the second deployment charge will fire after
apogee during descent at 150 feet below apogee. One of the many
possibilities for this setting is to click a camera after the rocket's
descent has stabilized.
To simulate rocket liftoff it is necessary to pull a vacuum on
the top of the pressure sensor (small component with hole on top). An
eighth-inch diameter piece of plastic or rubber tubing can be used. You
need only hold the vacuum for a few seconds, then slowly release.
However, the best method is to put the whole device (including wires and
flashbulbs for testing the output switches) 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 DDCS25 will BOOP to indicate that 300 feet has
been reached (liftoff). Then when the altitude starts its descent
(vacuum is being released), a BEEP will indicate that the maximum
altitude was reached, and this is when the first output (apogee)
flashbulb fires. When the simulated altitude falls to the user selected
altitude above the original ground level, there will be a long BEEP, and
this is when the second output flashbulb fires.
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. NOTES ON MOUNTING AND INSTALLING The DDCS25 may be installed lengthwise in a
small-diameter rocket tube. It will fit lengthwise in a 38 mm ID tube.
Also, it may be mounted lengthwise on either side of a center plate
inside a 54 mm tube. In larger tubes it may be mounted flat against a
bulkhead. The mounting holes are .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.
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 vacuum caused by the aft end of a
rocket during flight. 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.
The 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
directly 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
could affect the altimeter. Multiple ports evenly spaced around the
rocket tube may help cancel the effects of strong wind, 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. 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.
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 four diameters before
it dissipates. 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 judgment 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. DDCS25 Dual Deployment Controller™ DDCS25-100K Dual Deployment Controller™ ADDITIONAL ACCESSORIES
Additional CAB6L-24 Additional GP-23A 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. They are used on the DDCS25 to program the value for the
Second Output Function, the output that fires the Deployment Charge for
the Main Parachute.
Shorting Jumpers Electronic Instrumentation is not compatible with the 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 DDCS25 when used in a dual redundancy backup
system is the ALTS25. The ALTS25 would function as the primary device to
measure altitude and to control Dual Deployment™. The DDCS25 would
function as the redundant backup device to also control Dual Deployment™.
The ALTS25 measures altitude to 25,000 feet with deployment that
functions to 60,000 feet. The ALTS25-60K extended version measures
altitude to 60,000 feet with deployment that functions to 100,000 feet.
ALTS25 Maximum
Altitude Altimeter with Dual Deployment™ www.adeptrocketry.com 9-18-08 |
