Blue Jay Altimeter

The Blue Jay altimeter is the easiest rocketry altimeter to install and use. With its built-in magnetic switch, just connect a battery and your e-matches and you are ready to take your rocket to the pad. Turn the altimeter on with the included magnet and the Featherweight UI phone app connects over Bluetooth to show you everything you need to know that the rocket is ready to fly. Then when you walk up to the rocket after it lands, the phone automatically downloads and displays the flight data on your phone. The Blue Jay includes the most important features of the Blue Raven altimeter at about half the price.

Bottom view

Top view, with pen for scale

Easy installation and connections

1.45" long by 0.65" wide, fits into an 18mm Estes BT20 tube
4.7 grams
Mount in any orientation
Two screw terminals per e-match
Mounting holes for 4-40 screws (included)
Magnetic switch has approx. 2" range
Compatible with any size battery up to 12V (1s lipo recommended)
The two outputs are designed for e-matches
- Apogee channel settings are customizable, with default apogee settings use 3-sensor voting for apogee detection
- Main channel settings are customizable with default main chute deployment at 700 feet above the pad (AGL)
- Automatic current limiting to 1 Amp
- Automatic brownout protection by turning off outputs if onboard voltage drops too low.
- Continues to operate after power interruption for approx. 15 msec
- Default main chute deployment at 700 feet

Sensors and data recording

3-axis acclerometer (+/- 32 Gs) and gyros (+/- 2200 deg/sec) used for on-board inertial navigation (raw measurements not recorded)
50 Hz barometric sensor altitude and temperature
50 Hz tilt angle, roll angle, and predicted tilt +3 seconds
50 Hz vertical velocity, down-range horizontal velocity and cross-range horizontal velocity
50 Hz battery voltage and continuity voltage on both outputs
50 Hz recording of all flight events used for deployment logic

Easy operation with the Featherweight UI app

The ground test capability remotely tests your charge sizing while automatically recording slow-motion video
At the pad, know when your rocket is Go For Launch from your phone screen. No more listening for beeps on the pad or peering into vent holes.
All the data from your flight is automatically transferred to your phone when you walk up to the rocket after it lands.
Easily modify the default deployment settings with screens tailored for easy access to the most common functions like low altitude main chute deployment, or go for the custom deployment setting screen to get access to the 22 flight events and thresholds that can control each output channel. The Plus model allows outputs to fire before apogee for advanced use cases like multi-stage flights.
A sophisticated built-in flight simulation exercises all sensors and all outputs. Verify that your e-matches work with your battery, verify your flight program, and view all the recorded data from your "flight" from your phone.
All recorded data can be saved as text files you can share or email with all the capability of your phone.
The app provides over-the-air (OTA) embedded software updates to your Blue Raven hardware so that your Blue Raven can take advantage of all the new features and improvements as they become available.

$80 Blue Jay

Simple, easy, and low-cost 2-output deployment altimeter. Outputs can be programmed for any events at apogee or later.

$29 Blue Jay Power Starter Kit

Everything you need to power your Blue Jay, ($35 if purchased separately) Includes:

Featherweight Dual Battery Charger
Blue Jay 1s lipo battery
Battery connection wires with connector

$100 Blue Jay Plus

The version of the Blue Jay that can program the outputs to fire e-matches before apogee, for multi-stage flights

Blue Raven separate accessories

Magnet

$3.00 - $15.00

Rare-Earth permanent magnet for use with magnetically-activated switches and av-bays. The standard magnet is easy to use and has a range of about 1". The extra-large magnet is powerful enough to be pinch hazard and is difficult to remove from a steel plate. It has a range of about 2".

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Altimeter Battery

$15.00

Small Raven-compatible battery for powering the altimeter and the deployment charges. Battery capacity and ranges from 130mAhrs to 160 mAhrs, and the original brand may vary. No cell protection is built in, which allows full current to fire the deployment charges. The MCX connector is compatible with all Featherweight av-bays, including the Power Perch, 38mm, 29mm and 24mm av-bays. Note that the higher-capacity versions of this battery are longer, which may require modification to, or removal of, the wooden battery restraints provided in the 29mm and 38mm av-bays.

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Dual Battery Charger

$24.00

A dual charger that will charge a tracker battery and an altimeter battery at the same time. It's a convenient way to top off your Featherweight batteries at home, in the field, or mounted on your rocket:

Small size, 0.7" x 0.92" (about the size of a postage stamp)
Arranged so the USB input connector can be on the outside edge of a sled while the battery connectors face toward the inside
The Raven and Tracker batteries each have 2 through-hole pads to connect wires to the Raven or Tracker without ever needing to disconnect the battery.
One mounting hole for #4 or M3 screw

Each battery has its own status LED. Orange for has power, no battery connected, red for battery is getting charged, and green for good-to-go! In the photo to the left, the tracker battery is still charging and the altimeter battery is done.

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