(Contributed - by Drake Damerau - 09/05/05)
The G-Wiz LC Deluxe has both a G-force sensor and a barometric sensor for
launch detect, motor burnout and accurate altitude determination. Because of
this, it is not affected by Mach transitions. Having two sensors enables it to
add an additional output channel for clustering, staging or air-starts.
Pyro output 1 - Jumper select between Launch detect for clusters and
Burnout detect for staging or air-starts
Pyro output 2 - Fires at Apogee detect for drogue deploy.
Pyro output 3 - Fires at a fixed low altitude for main chute deploy.
The G-Wiz comes in a pre-set main chute deployment altitude: 400 feet or
800 feet. I have both units, but this still limits your options.
Status LED shows continuity before launch, and maximum altitude upon
landing. It is also able to tell you how you have the unit wired and the
jumpers set. Having lights instead of a can be bothersome because you
have to look through a hole in the altimeter bay, instead of just listening
from the ground. This can be a pain when your hole is 15 feet off the ground.
It can use one or two batteries for operation. One battery will power the
board and fire the e-matches. You can also use two batteries by removing a
jumper wire. Using two batteries separates the board from the pyro channels.
This ensures you have full power to the board during an e-match firing. There
is not a battery mount on the board like some altimeters. I like this feature
because it allows me to use whatever battery I want and put it wherever I want.
I usually use two standard 9v batteries.
For arming and disarming [for every altimeter I use], I use the push on /
push off switches that PerfectFlight sells. I like to mount all my altimeters
with plastic PC board stand offs and stainless steel screws, onto a
¼" aircraft plywood board.
I have flown both of these altimeters a few times, without fail. The
"motor burn-out" channel works flawlessly for air starting my large
two-stage rocket. Although I only use altimeters in big rockets, its small size
allows it to fit in 29mm airframes.
Having three output channels makes this one of my favorite altimeters. It's
slightly harder to use than some of the simple two channel altimeters out there
so a careful study of the directions is required.
out of 5
Deluxe 800 review is provided courtesy of:
G-Wiz LC Product Review
G-Wiz Partners manufactures rocketry electronics that can be used to collect
maximum altitude, control parachute deployment and ignite the motor of a
two-stage rocket. With some creative thinking the devices can probably be put
to other uses, too, like camera activation upon launch.
There actually are two partners that comprise G-Wiz Partners: Robert Briody
and Larry Lynch-Freshner. Like most of the companies that make rocketry
electronics, G-Wiz Partners is a part-time business. The partners decided that
they could build a better device than what was already on the market.
One of G-Wiz Partners' doctrines is that an accelerometer is a better way to
detect apogee than an air pressure sensor. Many rockets arc over apogee and
fall, sometimes several hundred feet, before a barometric-only altimeter
activates the apogee event. This can cause a rocket to gain significant speed,
which can adversely affect recovery. A barometric sensor is used to measure
maximum altitude and altitude during descent so that when used for two-stage
recovery the main parachute can be deployed at a low altitude, such as 800'
above the ground.
An accelerometer makes an altimeter immune to Mach transitions, which can
fool barometric sensors into activating ejection charges at the wrong time.
(Some barometric altimeters have a "Mach timeout" feature to avoid
An accelerometer allows the device to be used for more than just determining
apogee. It can be used to activate another device upon motor burnout, such as
an igniter for staging.
G-Wiz Partners, at the time that this review was prepared, makes three
products: G-Wiz LC, G-Wiz LC Deluxe 400 and the G-Wiz LC Deluxe 800. This
review covers the G-Wiz LC Deluxe 800, which will hereafter be called the
"800". The G-Wiz LC Deluxe 400 is exactly the same as the 800 except
that it deploys the main parachute at 400' above the ground rather than at
800'. The suggested retail price is $134.95. (The "LC," by the way,
means "Low Cost".)
The most common usage of an 800 may be as a recovery system controller for
. Two-stage recovery means making a rocket non-aerodynamic at
apogee, usually by separating a rocket into two sections so that it falls
rapidly but not as quickly as when in a ballistic nosedive, and then deploying
the main parachute at a low altitude, such as 800' above the ground. Two-stage
recovery can result in nearby recovery even when a rocket flies to a high
The 800 has three electrical outputs. When used for two-stage recovery two
outputs are used. One is used to fire a separation/deployment charge at apogee.
The other output fires an igniter to deploy the main parachute at a low
altitude. The device is configured at the factory for a low altitude of 800'
above the ground, which cannot be altered by the user.
The 800's third electrical output can be used to ignite additional motors
after launch or to start a two-stage rocket's sustainer's motor upon booster
motor burnout. When used for recovery system control this output is not used.
LED's (Light Emitting Diodes) are used to report device status. Each
electrical output has an LED to indicate if there is continuity through an
igniter. A fourth LED reports pre-launch status and post-flight maximum
The manufacturer recommends the use of two batteries when the device is used
for anything other than collecting and reporting maximum altitude. One battery
powers the computer. The other battery is to fire the igniters. When only one
battery is used the potential exists for a power brownout when igniters are
fired, which could cause the computer to reset and cause a recovery system
The recommended power source is a standard 9 volt alkaline battery. These
batteries weigh nearly 2 ounces each, and two can be a lot of additional weight
for a small rocket. G-Wiz says that 12 volt A23 batteries can also be used,
though they have a shorter life than 9 volt batteries.
The G-Wiz LC Deluxe 800 consists of a narrow circuit board. Like most
rocketry electronics it does not have a cover. An accidental electrical short
could cause ejection charges to fire. The board, with the exception of the air
pressure sensor, can be covered with RTV silicone that is safe for electronics.
Upon request, the manufacturer will encase the board in epoxy for an extra
$15.00, which also adds strength.
The manual consists of four pages. A person already familiar with rocketry
electronics should not have a problem using a G-Wiz product. A person new to
rocketry electronics, however, may be left perplexed. Although it is not the
responsibility of G-Wiz Parters to provide plans for adding an electronics bay
to a rocket, or to identify where appropriate separation/ejection pyrotechnics
igniters can be purchased, some pointers would be helpful. A beginner should
seek advice from an experienced person. (Pratt Hobbies' web site contains a
G-Wiz frequently asked questions (FAQ) document that can help. The document is
not available from the G-Wiz Partners' web site. An email mailing list -
G-Wiz@egroups.com - is also available.)
The manual warns about reversing the battery's polarity multiple times but
doesn't always state why. The reason for the warning is that any attached
igniters will immediately fire if polarity is reversed. Reversing polarity
won't harm the computer.
Because G-Wiz Partners is a small, part-time company, the owners expect the
seller to be the first line of support. However, support directly from the
manufacturer is available.
Contacting the G-Wiz Partners turned out to be a more interesting journey
than anticipated. The manual does not include a street address, telephone
number, email address or web site address. An attempt to locate the company
through the web sites of Rocketry Online, Rocketopia and Pratt Hobbies all
failed. The G-Wiz Partners' web site was eventually located through the use of
a search engine, and an email address was found, but the address didn't work. A
call for help on the Internet Usenet group rec.models.rockets quickly resulted
in another email address to contact one of the partners, and another attempt
was made. A response was quickly received, and Robert Briody was peppered with
questions over a few days, all of which were professionally answered within 48
The 800 was flown in a rocket that contained an existing electronics bay.
The bay has a small hole for venting, which has worked with other altimeters.
The status LED's could not be seen. Because there was no audio status reporting
one could only assume and hope the G-Wiz was ready for flight. Additional holes
could have been drilled into the bay so the LED's were viewable, but that would
have affected the bay's use with other altimeters.
Daveyfire N28B igniters were used to ignite the ejection charges. The apogee
and low altitude black powder charges each contained two igniters.
The rocket rose to apogee, arced over and continued a ballistic descent to
the ground. Neither the apogee or low altitude charges fired. The airframe was
totally destroyed by the fall from 1400'. The motor, parachute, electronics bay
and the 800 survived. The 800 passed post-crash bench tests. The cause of the
crash has not been determined. However, it is believed that the 800 either lost
power on the ground or during flight, or it failed to detect launch. The custom
battery holder might have been the cause. The 800 was installed in the correct
orientation required by the accelerometer. All wires were still firmly attached
after the crash. If the problem occurred during flight preparation and if the
LED's had been viewable, or if audio status reporting was available, the crash
might have been prevented. A different 800 has been observed to perform
correctly when it was used for staging and booster recovery.
Combining an accelerometer and barometer into a single altimeter is a good
idea. An accelerometer should do a better job of detecting apogee than a
barometer. The G-Wiz LC Deluxe 800 altimeter is such a device. It is also
compact, lightweight (without batteries) and can be used for more than just
recovery system control. However, it could use some improvements, and there is
a cautions about its use.
The G-Wiz altimeters need audio status reporting. Without audio status
reporting use an electronics bay that allows the status LED's to be viewable
when the rocket is on the launch pad.
A user selectable low altitude is desired. The G-Wiz LC Deluxe 800 has only
one low altitude setting - 800' above the ground. The desired main parachute
deployment altitude can vary from day-to-day and flight-to-flight depending
upon wind speed and direction and rocket weight. A higher main parachute
deployment altitude can be desired with a heavy rocket or a rocket that uses a
complex and slower opening parachute system, like a parachute ,
to ensure enough time for the recovery system to correctly function. Sometimes
a few extra seconds can be needed to shake out a problem like a tangle.
However, a higher altitude can also mean more drift if the parachute opens
quickly. Therefore a lower altitude, like 400' above the ground, may be desired
for rockets with simple and fast opening recovery system.
When one battery is used to power the computer and another battery is used
to power the igniters, current flows through attached igniters as soon as the
battery that powers the igniters is attached, even if the computer is turned
off, even if the battery the powers the computer is not connected. Therefore a
rocket either needs two switches, one for the computer battery and one for the
igniters' battery, or the rocket cannot be prepared for flight until shortly
before it flies or the battery for the igniters will slowly drain. Also, if a
rocket isn't flown after being prepared it must be torn down to remove the
igniter battery. This may be true of any altimeter that uses separate batteries
for the computer and igniters.
A means to avoid needing two batteries should be considered. Other rocketry
altimeters function fine with a single battery.
Pros: Combines an accelerometer and barometer in a single altimeter
Cons: Lack of audio status reporting
Written and submitted by Dean Roth for Rocketry Online -- Copyright