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!

Works Up To 45,000 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.

A Single 9V Battery Controls Everything!

A single 9V battery 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 a low current e-match or other low current igniter like the Quest Q2G2 igniter. (Igniters and ejection charges are not included).

User Selectable Main Parachute Deployment Altitude

You determine the altitude you want the main chute to eject. Choose altitudes anywhere between 400 to 1,300 feet in one-hundred foot increments. This programming is done by installing the shunts on the device prior to flight (see instructions for use).

Mach Delay Setting for Supersonic Flights

The mach delay setting is used to prevent premature deployment of the drogue parachute as the rocket makes the transition between subsonic flight and supersonic flight. During this period the pressure surrounding the rocket suddenly increases -- which could be interpreted as a decrease in altitude (see below about how altitude is determined). This condition would cause the altimeter to think the rocket has gone past apogee, and it would fire off the ejection charge to deploy the drogue chute.

"Mach delay" forces the device to prevent firing the deployment charge for a predetermined amount of time (that time period where the rocket is traveling at supersonic speeds). After the time period has expired, the device will go back to normal operation and sample the air to determine the altitude of the rocket. If your rocket is expected to go supersonic, you must turn this feature on (see instructions on how to set up the device) for proper deployment to occur.

 

How do you determine how much "delay time" to use as you are setting up the Mach delay feature? Great question. You perform a rocket flight simulation using the RockSim software. It can show you during what time interval the rocket is traveling at supersonic speeds. We recommend it for all rocket flights, particularly for complex flights that might use dual deployment.

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.

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.

Beeps out the Peak Altitude After The Flight

The device can also be used as a simple altimeter. The first difference between this one and the Alt15K/WD is that this altimeter can operate up to 45,000 feet above sea level. But this altimeter does not have data storage capability that can be downloaded to a computer. So you do not need to order the Data Transfer Kit for your computer.

 

Capable of Firing Off Any Igniter

The HiAlt45K will fire off any igniter that requires less than 5 amperes of current. Other dual deployment devices, like the PerfectFlite minAlt/WD will only fire low-energy electric matches. This gives you a lot more choices on which ignition devices to use to fire off your deployment charges.

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.

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.

Continuity Of The Igniters Reported

When you power up the device, it will report the status on the igniter continuity. That way you will know if your rocket is fully 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.

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.

Low battery alarm

The altimeter sounds a continuous tone if battery voltage drops below 5.5 volts. At this point, the battery needs to be replaced immediately before flying the altimeter. You can test your batteries before you get out to the launch field.

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.

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 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.

Mounting Hardware Included!

Your dual-deployment altimeter comes with the mounting hardware shown here. It also includes a 9V battery hook-up, and 5 small shunts that are used to program the altimeter prior to flight.

For further information on mounting the device, please see the book Modern High Power Rocketry.

The PerfectFlite HiAlt45K payload works by sensing the altitude of the rocket. In simple terms, it is an altimeter. But this one is different, it has more brains and extra hook-ups to to send electricity to two different ejection charges.

As the rocket takes off, this electronic payload is calculating the altitude of the rocket. When it senses the peak altitude, called apogee, it sends electricity to one of the igniters. This igniter 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 controlling the deployment of the two recovery devices, it also records the peak altitude that the rocket reached. So after the flight, you can find out exactly how high your rocket flew. You don't need to carry a separate altimeter in to the air, so you save some money!

In this first video, we'll explain what dual-deployment (ejecting two separate parachutes) is, and explain how the Entacore Dual-Deployment Altimeter works that controls the rocket.

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.

Setting up and handling black powder for ejection charges can be dangerous. Be sure to read the precautions in the HiAlt45K user's Manual.

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 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.

Q. 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.

Q. 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.

Q. What barometer this does this particular altimeter use and what is the lowest pressure it can read?

A. According to the manufacturer, PerfectFlite, the barometric sensor is the Freescale MPXH6115A6U. The lowest pressure it will read with full accuracy is 15 KPa. This corresponds to 44,320 feet above sea level.

Q. 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.

Q. How does this electronic gizmo compare to other dual-deployment devices?

A. This device uses a single barometric sensor to determine how high the rocket is. The G-Wiz Flight Computer uses both barometric and accelerometer sensors to determination of the rockets altitude and orientation. This provides a bit of extra redundancy, but of course, it also comes with a higher price-tag.