Adept Rocketry - ALTS1 Instructions and Data Sheet
ALTS1 and ALTS1-50K
Maximum Altitude Altimeter with Deployment
Copyright © 1989-2010, All Rights Reserved
ALTS1 Maximum Altitude Altimeter with Deployment
ALTS1-50K Maximum Altitude Altimeter with Deployment
The ALTS1 Altimeter with Deployment is a maximum altitude altimeter that measures and reports the maximum above-ground altitude value obtained during a rocket's flight. The ALTS1 also has an altitude controlled deployment switch that is typically used to fire a deployment charge, based on altitude. In one mode the charge fires when the rocket reaches its maximum altitude (apogee), or the charge may be programmed to fire when the rocket descends to 500 feet above ground. The most common usage is to deploy a main parachute at apogee.
This device is used in rockets that will reach at least 300 feet altitude. The deployment switch may be used, or the device may be used as a maximum altitude altimeter only. The ALTS1 may be used in any rocket configuration including multistage rockets, in which case maximum altitude information about a particular stage can be obtained by placing the device in the particular stage of interest. Or individual ALTS1 units (or other altimeter devices) may be placed in each stage of interest to report the maximum altitudes obtained by each stage, and/or to handle deployment for each stage.
The ALTS1 precisely captures the highest altitude obtained during a flight to a maximum of 15,000 feet above sea level. The extended ALTS1-50K version functions to 50,000 feet above sea level. The maximum value obtained above the local ground-zero altitude is precisely measured and reported in one-foot increments (one-foot resolution).
The ALTS1 measures 0.9” wide by 0.65” thick by 4.25” long. It fits inside a tube with a minimum ID of 24 mm, or 0.95 inch. The device weighs only 24 grams (0.85 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 ALTS1 is a totally stand-alone device including the battery holder, arming mechanism, and current source for firing a deployment charge. Nothing more is required except for the wires (interconnect cable) that connect to the On-Off switch and to the deployment charge.
The altimeter uses a custom absolute pressure device to precisely measure altitude values up to 15,000 (or 50,000) feet in one-foot increments. It uses a 16-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 ALTS1 reports whether or not the deployment charge has continuity. It also constantly measures the ground-level altitude and waits for a quick 300-foot change upward. It then captures the maximum altitude obtained above ground zero. If programmed to do so the ALTS1 fires the deployment switch at the very moment when the rocket reaches the maximum altitude. Or it may be programmed to fire the deployment switch when the descending altitude reaches 500 feet above the ground. The ALTS1 uses the copyrighted and patented and trade marked technique of beeping out (blinking on some models) a value to report the maximum altitude value. The beeps can be heard even when the unit is still inside the rocket. The rocketeer knows the maximum altitude as soon as he/she picks it up, or just gets close to it. Note: the ALTS1 cannot be used for, and will not function for, maximum altitudes less than 300 feet.
TESTING AND USING THE ALTS1
NOTE 1: The precision amplifier circuitry and continuity sensing circuitry on the ALTS1 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: This device must be installed only in a “clean area.” Electronic Instrumentation is not compatible with the fumes and residue created by rocket motors and deployment charges. The ALTS1 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 CAB5-xx series interconnect cable to the 5-pin connector on the ALTS1.
The BLACK and BROWN wires enable power to the altimeter when they are connected together. They may be connected to an On-Off switch.
The RED and ORANGE wires connect to the deployment charge.
The YELLOW wire of a standard CAB5-xx series interconnect cable is not used.
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 beep when powered up, to indicate proper operation. After ten seconds of silence the unit starts beeping every 1.6 seconds to indicate that it is now taking altitude readings and is waiting for liftoff.
If a flashbulb (or low-current electric match at a safe distance) is connected (don’t connect anything quite yet), the beeping changes from a single beep to a double beep to indicate continuity of the deployment charge. A single beep indicates proper operation with no deployment charge connected. A double beep indicates continuity of the deployment charge.
SETTING THE OUTPUT SWITCH TO FIRE AT APOGEE, OR AT 500 FEET AGL
When viewing the front of the ALTS1 vertically (with the cable connector at the top, and the battery holder near the bottom), a two-pin connector is located at the upper right of the battery holder. When no jumper is installed on the connector, the default setting is FIRE AT APOGEE. When a shorting jumper (Radio Shack Cat. No. 276-1512 or equivalent) is installed vertically on the two pins, the setting is FIRE DURING DESCENT AT 500 FEET ABOVE GROUND LEVEL.
To simulate rocket liftoff it is necessary to pull a vacuum on the top of the pressure sensor (the black component with four pins). A quarter-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 a flashbulb for testing the output switch) 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 ALTS1 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 flashbulb fires, if the programming jumper is NOT installed. If the jumper is installed, the flashbulb will fire when the simulated altitude falls to 500 feet above ground. There will be a long BOOP, and then the unit begins reporting the maximum altitude.
After a flight, the altimeter will be beeping out the maximum altitude in this manner: (1,321 feet) Beep.....Beep Beep Beep.....Beep Beep.....Beep. A zero is indicated with a long Beep: (1,302 feet) Beep.....Beep Beep Beep.....Beeeeep.....Beep Beep. After each sequence there is a long pause before it repeats. The system works for three, four, or five digits depending on the value. This beeping technique and system is copyrighted and patented, and is a registered trade mark of Adept Instruments, Inc.
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 ALTS1 may be installed lengthwise in a small-diameter rocket tube. It will fit lengthwise in a 24 mm ID tube. Also, it may be mounted lengthwise on either side of a center plate inside a 38 mm tube (an ALTS1 along with a DCS1 may be mounted back-to-back). 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 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 judgement 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.
ALTS1 Maximum Altitude Altimeter with Deployment
ALTS1-50K Maximum Altitude Altimeter with Deployment
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 ALTS1 to program the value for the Output Function, to fire at apogee when the jumper is not installed, and to fire at 500 feet above ground when the jumper is installed.
Chamber, Complete with Bottle.
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 ALTS1 when used in a dual redundancy backup system is the DCS1. The ALTS1 would function as the primary device to measure altitude and to control deployment. The DCS1 would function as the redundant backup device to also control deployment If one of the devices is programmed to fire a drogue chute at apogee, and the other is programmed to fire the main parachute at 500 feet above ground, then the technique of Dual Deployment™ can be implemented.