| You Control When the Parachutes are Released
Are you tired of chasing your rockets for long distances? Wouldn't it be nice if they didn't drift such a long way and still came down slow enough that they weren't damaged? Then you could fly really big and high-altitude rockets even when it was windy.
The solution is a dual-event electronic payload that controls when the parachutes are ejected out of the rocket.
The concept is simple. Instead of flying a single large parachute to bring the rocket down slowly all the way from deployment, you use two different parachutes.
You eject a small parachute or streamer out of the rocket at apogee. It then falls very quickly and therefore doesn't drift very far. When the rocket is closer to the ground, say 500 feet up, you pop out a big chute to slow it to a safe landing speed. It is a great solution!
| Main Features
Records data for up to 16 separate flights!
- Records data for 16 flights, up to 18 minutes each. Data (altitude, temperature, and battery voltage at 20 samples per second) for each is downloadable to provide graphs of your flight. After 16 flights, the 17th and sequential flights will replace the oldest flight data, so that you always have the 16 most recent flights' data.
Works Up To 100,000 feet!
- This unit is meant for nearly all your high power rocket projects, including those really high altitude flights that might otherwise drift miles and miles if you used single-parachute recovery.
The real-time altitude data can be acquired through the use of built-in telemetry capabilities. You will need to provide your own RF modem to enable this feature.
A Single 9V Battery Controls Everything!
- A single 9V battery (will accept a battery between 4 and 16V) powers the micro-computer on the gizmo that senses and determines the altitude of the rocket, and will also set off the two ejection charges via ematch or other starter (starters and ejection charges are not included). Do not exceed a 10A current, less damage to the Stratologger's circuitry may occur.
Apogee Deployment for the Drogue Parachute/Streamer
- Firing the first ejection charge exactly at apogee insures that the drogue recovery system is deployed while the rocket is traveling at the slowest possible speed. This minimizes the likelihood of rocket damage due to "zippered" body tubes and stripped parachutes. Electronic deployment is preferable to using the engine's built-in timed ejection charge, which can vary from engine to engine. Also, if the rocket weathercocks excessively the time delay in the engine may be too long and deploy the parachute too late and cause a zipper or a shred. Electronic payloads, like this one have saved a lot of rockets from an early demise.
User Selectable Main Parachute Deployment Altitude
- You determine the altitude you want the main chute to eject. Choose altitudes anywhere between 100 to 9,999 feet in one foot increments. 9 presets allow for quick change on the field.
MachLock feature for Supersonic Flights
- Velocity data is analyzed on the go so as to eliminate incorrect drogue deployment due to "Mach dip," or the apparent drop in altitude due to increased pressure when the rocket reaches super-sonic speeds. On altimeters without velocity analysis, Mach dip can be incorrectly interpreted as apogee. This in-flight analysis eliminates the need for older Mach delay setting technology.
With MachLock, you don't have to worry about remembering to set the Mach delay on the field - apogee will be determined correctly regardless of rocket speed and your memory.
Can Also Be Used As Single-Deployment Device
- You do not need to configure the device to deploy two parachutes as separate events. You can set it up to just deploy one parachute at the apogee point in the flight. This could be used to provide redundancy to a standard motor ejection charge. So if the motor's ejection charge fails to fire at the right time, or if the rocket weathercocks strongly into the wind and the motor ejection would occur way too late in the flight, the apogee ejection would "save" the flight. It provides that extra reliability to make sure that your rocket will survive to see another flight.
Capable of Firing Off Any Starter
- Outputs capable of 10A current for 1 full second to allow use with nearly any ematch or ematch substitute. Reverse polarity protection prevents spontaneous firing if battery is connected backwards.
| Additional Features
Hook-up For External On/Off switch
- The device also has a separate hook-up where you can (recommend) attach a on/off switch (not included with the device). This gives you some extra protection while hooking everything up for flight. Remember, you're getting ready to set up extra black powder to kick out the parachutes, and for safety reasons, you don't want to set off one of those charges prematurely. That's why you don't want to power it up until it is on the pad and ready to launch.
Brown Out protection
- The altimeter can survive a 4 second loss of power without affecting operation. If the battery or switch terminals break connection momentarily during hard acceleration or chute deployment shock, the altimeter will continue to operate properly. While the altimeter will continue to operate during momentary power outages, the ejection outputs will not fire if power is absent at the point that they are turned on.
Built-in battery voltmeter
- When you first turn it on, the altimeter reports the current battery voltage. No more guessing about whether the battery is good or bad and whether it needs to be replaced soon. You'll save money, because you won't be replacing a perfectly good battery.
Mounting holes for increased mounting flexibility
- Want to fly multiple altimeters at the same time? Then it makes sense to attach them to a mounting plate inside the rocket. They'll then have all the same experiences and you can make an apples-to-apples comparison or get redundant back-up data. Note: Mounting hardware (screws) is NOT included
Even though the altimeter can be mounted firmly in the rocket, it is small enough and lightweight enough that it can also be slip it into a padded tube for quick installation into the rocket.
Launch Detect Altitude Preset to 160 feet
- Launch detect tells the altimeter when the rocket has started moving upward and that it should start saving the altitude-vs-time data to the memory chip on the unit.
This higher Launch Detect value offers more resistance to false triggering due to wind gusts while the rocket is sitting on the pad.
Continuity Of The Starters Reported
- When you power up the device, it will report the status on the starter continuity. That way you will know if your rocket is fully ready to launch.
Power loss detection
- The altimeter will sound a distinctive hi/low alarm tone sequence on power up if power was lost during the last flight. This doesn't happen very often, but it could tell you that there was some anomaly during the last flight.
| How Does This Dual Event Payload Work?
The PerfectFlite StratoLogger payload works by sensing and recording the altitude and interpreting the velocity of the rocket. Being a smart altimeter, it then uses this recorded data to know when to set off up to two ejection charges to deploy parachutes for the best recovery.
As the rocket takes off, this electronic payload is calculating the altitude and velocity of the rocket. When it senses the peak altitude, called apogee, it sends electricity to one of the starters. This starter sets off a small charge of black powder. That pressurizes one section of the rocket and spits out the small parachute (called a drogue chute).
While the drogue chute brings down the rocket quickly, the payload is still sensing the altitude of the rocket. When it descends to a pre-programmed height (which you control), it then triggers a second time. This time is ignites another black powder ejection charge which pushes out the main parachute. Since the rocket is now closer to the ground, the wind really doesn't have the time to push it downrange too far. So it lands slowly, but much closer to the launch pad. That means you don't have to walk very far to retrieve your rocket.
Besides using the data to control the deployment of the two recovery devices, it also records it in such that you can download the data to your computer after the flight and see exactly what went on with altitude, temperature and battery voltage - acceleration and velocity are derived using the downloadable software. The amount of data recorded in an altimeter of this price range is phenomenal - you won't need another! Besides being able to download the data, the altimeter also beeps out the peak altitude and other data points so you can write it down on the fly when you don't have your computer with you.
Actual Customer Photos and Comments:
Tim Stone writes: "I thought you might like to se how I mounted the Stratologger Altimeter and rotary switch for my Madcow Torrent. It is mounted on 1/16” ply, glued & screwed the sled. A 1/4” hole in the coupler serves both as a static port & access to the switch. The ¼” sled ply has been filed at an angle so the switch face is parallel to the body tube. I appreciate you Apogee’s service to the sport." (See below for larger images...)
Setting up and handling black powder for ejection charges can be dangerous. Be sure to read the precautions in the StratoLogger user's Manual.
Frequently Asked Questions about the PerfectFlite StratoLogger Altimeter CF
Is this altimeter approved for use in the TARC competition
A: No. Not yet, at least (as of May, 2010). It is something we'd like, but it has to go through a formal approval process to be certified for the TARC competition. See the official web site of TARC to find out if it has been approved for use. Please ask them to approve it, don't ask us -- we're doing our part already. But in the mean time, it makes a great practice altimeter for your first test flights.
How Do Altimeters Work?
A: The barometric altimeter measures the air pressure surrounding the rocket. Air pressure near the ground is greater than air pressure high in the air (remember, air pressure decreases with altitude, until you reach the vacuum of space, where there is no air pressure). What the unit does is to compare the pressure it senses during flight, to the air pressure on the ground. Using a simple formula, it automatically computes the altitude difference that caused the change in pressure.
How Altimeters Work - A Tutorial
How accurate are altimeters? Which is the best one? These are common questions that are hard to answer, because of the randomness of the atmosphere. This video explains what that means and how it relates to the accuracy of electronic altimeters.
For More Information: See our Peak-Of-Flight Newsletters. Issue #240, Issue #242, and Issue #257
Do you sell any type of ejection charges that could be used with the device on this page?
A: No. The ejection charge is always made from loose black powder. Because black powder is regulated by the government, you have to purchase it from a gun store (one that specializes in muzzle-loading supplies). You also need to be at least 18 years old to use loose black powder in this manner.
Does it matter what elevation the launch field is?
A: The altimeter samples the air on the ground, so it knows the altitude of the ground level. So when you set it to deploy the main chute at 500 feet, it will know that is above ground level. It doesn't matter where you start.
How easy is it to set up dual-deployment?
A: To be honest, it is not a beginner-level operation. For starters, you have to design your rocket with two separate parachute compartments. This is detailed extensively in the book Modern High Power Rocketry 2. We highly recommend this book if you are new to large rocket or dual deployment techniques.
How Does This Recording Payload Work?
A: This PerfectFlite altimeter payload works by sensing and recording the altitude and interpreting the velocity of the rocket. It records the altitude as such that you can download the data to your computer after the flight and see exactly what went on with altitude, temperature and battery voltage - acceleration and velocity are derived using the downloadable software. The amount of data recorded in an altimeter of this price range is phenomenal - you won't need another! Besides being able to download the data, the altimeter also beeps out the peak altitude and other data points so you can write it down on the fly when you don't have your computer with you.
How does it detect a launch?
A: While the unit is in stand-by mode, it is constantly monitoring the outside air pressure. As soon as the air pressure starts to drop, it figures something is happening. It starts recording information, but will discard it until it senses a pressure difference that equals 160 feet in altitude gain. If the pressure drops this amount, it considers a "true launch," so it stores all the information it has recorded.
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