project proposal

project proposal
The Stopwatch Variometer
Andrew Reilly
The Stopwatch Variometer is a device used by paragliding pilots to provide them with
beneficial aviating information. The device will calculate their altitude, change in altitude over
time, and behave as a stopwatch. This information can be used by a paragliding pilot to extend
his or her flight duration. The pilot will know if he or she is sinking in a pocket of air or rising on
a thermal and be able to adjust his or her flight pattern accordingly. The variometer is
dependable and gives accurate information while being portable with low power consumption.
Paragliding is a very expensive sport. Most new pilots spend $4000-$6000 on their
equipment. This price range only includes the necessities. A variometer is not a necessity but it
is a very useful tool to help build a pilot’s rapport with the air. Commercial variometers cost in
the range of $300 to $700. After buying the essentials, one is usually blinded by the price of a
variometer to see its true benefits. The variometers in the previously mentioned price range
include a lot of features that I do not deem necessary to help the pilot. These devices have
complex displays showing altitude, volume, battery, change in altitude, a timer, as well as many
other features. All of these features are shown at the same time on one screen. The display is
rather large and covers most of the devices face along with a multitude of buttons.
Flytec is a major company that produces an assortment of variometers. One of their
entry level models is the Flytec 6005 Vario. According to the description of the 6005 model
found on Flytec’s company website, the variometer features 3 altimeters, user-customizable
audio, 6 loudness settings, 250 hours of battery life, airspeed and more. The display features 5
data fields and the device has 6 user input buttons. This device provides a lot of features that
can be useful to a pilot, however most are unnecessary. The display looks extremely crowded
with a lot of data for a user to decipher. The Flytec 6005 is considered simpler model and can
be purchased online for $377. Other variometers, including those from other companies such
as Brauniger and Aircotec only seem to increase in complexity and price. They add multiple
other features as well as fancier displays such as compasses, GPS and wind direction.
Brauniger does have a Variometer called the IQ Alto that is available for £179. This
model is the simplest model I have seen, yet it still features 6 buttons and a display with 5 data
fields. The display is much cleaner and simpler than the Flytec 6005 and thus is better for
beginners to understand. By eliminating the complex features, Brauniger was able to make a
device that costs about half the price as Flytec and gives a less intimidating feel.
When a student begins flying, he or she has a lot to focus on. They do not have time to
look down and read the data off of the complex display. The display and large amount of
buttons can be very distracting to the pilot and could potentially become a safety hazard. Every
pilot keeps a log of their flights which includes their flight time as well as basic weather
conditions and altitude at takeoff. By limiting a variometer to only record and display the truly
beneficial information a pilot needs, distractions and confusion can be eliminated and the pilot
can still learn about their flight patterns and the air around them. The key elements a pilot
needs to know is his altitude, change in altitude and time of flight. All other features are
bonuses to the pilot, that really only become necessary once a pilot is comfortable flying
through the air and can safely make a landing using his or her own judgment.
After researching the parts required to make such a device I realized by keeping it
simple, the cost can be kept extremely low. As complexity goes down, so does the amount of
components required to make the device, and thus price and power consumption decrease as
well. Economically, a simple variometer becomes easily feasible. Building the Stopwatch
Variometer prototype should cost no more than $50. Once a design is solidified and the
process is finalized for building the device, the price should be reduced to under $30 and they
could easily be sold for $100. By keeping the price down and reducing the features and user
environment to only two buttons and one data field on the display, new pilots will be drawn in
to getting this helpful flying companion, and on their way to becoming a much better pilot.
Paragliding requires no fuel and thus the sport is very environmentally friendly. It only
consists of a man, a kite, and the breeze that raises his wing. This device is extremely low
power, using very little energy, and thus has a very minimal impact on the environment around
Socially, this device is directed towards beginning paragliding pilots. As the pilot gains
more experience and directs his or her flying skills towards cross country flying, he or she will
want to upgrade their variometer to one with GPS. Although it is directed towards beginners,
the device can be used by a pilot of any skill level and it will still be highly beneficial to them.
Paragliding is mostly popular in Europe. The gliders are mainly designed and sold by
distributors from European countries. This goes for the design and creation of variometers as
well. Building a variometer that can be easily available to American pilots, can help grow the
sport in the US. It can also make the US have a stronger influence on the sport by showing that
it can produce equally efficient tools for the paragliding pilot.
Most of the information a variometer provides to the pilot is not necessary to fly safely.
However, with this information a pilot will have a better understanding of the environment he
is in and be able to make better decisions for safely getting to the ground. Paragliding is
dangerous and any tool that can help make it safer is always beneficial to have. One branch of
paragliding is cross country where a pilot flies as high as they can and then crosses a valley to
get to the next mountain. The information a variometer provides can increase the pilots flight
duration and thus his flight time and keep him knowledgeable of when there are not any
thermals to ride up. He can then find a safe landing zone instead of pushing to go higher in
conditions that are not providing the necessary rise to do so. Having a simple device like this
variometer increases the ability of flying safely.
In order to design and manufacture the device, many constraints will need to be
followed. The Stopwatch Variometer needs to be portable and have a battery capacity to last
at a minimum of 24 hours. Variometers on the market can last over 40 hours using two AA
batteries. Most flights last no longer than an hour on average. The pilot could then use the
variometer for multiple flights and not have to change or recharge the device. As a portable
device size is a strong factor as well as power consumption. The Stopwatch Variometer needs
to be very low power and no bigger than a cell phone. By keeping it simple, designing this
device to be small with enough battery power to keep it running all day long should be an easy
Another design constraint has to do with the user interface. The display needs to be
able to show 1 data field, which at most will have 4 decimal digits. The display needs to be
visible in sunlight and bright enough to be seen in the dark. It also needs be able to be seen
from up to 3 feet away. This allows the device to hang or attach to a part of the body such as
the leg or wrist and still be visible by the pilot. The screen needs to be extremely low powered
and allow the user to be able to distinguish the data type he or she is currently viewing.
In order to make the device operational in any flying environment, it needs to follow
constraints regarding its effective altitude range. The barometric pressure sensor needs to
work between 0 and 30000 feet. Mount Everest is only slightly over 29000 feet. This means
the device should work at any altitude reachable by a paraglider. It also needs to be very
accurate in its measurement considering the air pressure is not always easy to detect due to the
many factors that can change it like wind and temperature. Its altitude detection will need to
be within 1 meter of accuracy. The temperature sensor has to be within 1 degree Fahrenheit of
The final manufacturing constraint is the way it attaches to the user. The device needs
to be non-impairing to the user during takeoff and landing, as well as not interfere with other
paragliding equipment. It needs to be sturdy and the user shouldn’t worry about it falling off or
being lost during flight.
Variometers operate by measuring the air pressure with a barometer and then
calculating the pressure using the surrounding air temperature. This means the device will
need a barometer, a temperature sensor and a microprocessor to sample both sensors and
calculate their value in understandable units.
The measurements this device makes will be very low power as well. The primary task is
to measure the pilot’s vertical velocity and beep to let the pilot know he is going up. The faster
he rises, the faster the device beeps. The second task is to measure the surrounding
temperature. A timer or stopwatch will be implemented as well to record the pilot’s flight time.
These three tasks are the most important part of the project. The results need to be accurate
and constant measurements will need to be made to make sure the vertical velocity is being
calculated correctly.
The next goal is to display the most important information on a display that is very
simple and easy to understand. One option is to use four 7-segment displays tied together to
display the numerical results. The device will display the current altitude, the temperature, and
the time of flight. One button will control the display and pressing the button will cycle through
the display options. The decimal point position will be used to differentiate the data and tell
the user which result is showing. The diagrams below show examples of what they will look like
along with the decimal position for each. One display I have looked at is a bubble display that is
very low power. The LEDs inside the display are small keeping power consumption low. The
small LEDs would ordinarily be hard to see, however, the bubble effect of the casing magnifies
the lights, creating a larger display. The display would be extremely simple for the user to
understand and it could be easily interfaced to a microcontroller.
Diagram of 7 Segment Display
The device needs to save power as much as possible so I plan on having a second button
to turn the device on and off. Once the button is pressed to turn it on, the timer will start and
the device will be completely initiated to start flying. This will keep the device extremely simple
to operate and the user will not have to worry about starting the device in the correct mode.
They can then focus on getting ready to takeoff. If the device does not change vertical velocity
for 30 seconds, the device will beep, thus reminding the user to either turn off the device if
they have already landed or to give a friendly notice that device is still on while flying.
Once the device is working correctly, I will focus on making it comfortable when
attached to a user. I have used commercial variometers that attach to the pilots leg, however, I
found this uncomfortable when taking off due to the required running. Online I found a
variometer that attaches to a lanyard to be warn around the user’s neck, however, this could
get in the way by swinging back and forth
when taking off and turning in the air. Also,
most pilots wear a chest radio which could
become hard to operate with another device
dangling over it. I will need to find another
way to attach the device to the pilot that will
not impair the pilot and is easily quickly
viewable. One idea is to attach it to the
wrist like a watch. This will keep it easily
accessible to the pilot and also out of the
way. The device will be small so it should
comfortably fit on even the smallest of
wrists. The diagram above shows the
general idea of what it will look like. This is not a finalized design but a general concept of the
idea and the simple style this variometer is designed to accomplish.
Once the device is completely ready, it would be nice to have it communicate to either a
computer or mobile device that can read the information from previous flights made. The pilot
can then analyze their flight and see when they were rising and sinking and view their altitude
in comparison to their flight time. This information can be very beneficial to the pilot. The
information would be displayed in graph form showing elevation vs time. In order to connect
to the variometer either Bluetooth or a USB connection will need to be used. This goal is not as
necessary but it is a hopeful outcome and possible future addition to later models, once the
basic model is finished and all bugs are worked out. Using a USB connection would provide the
ability to recharge the device instead of using replaceable batteries.
The prioritization of the goals for this project are as follows.
1. Read the barometric pressure and current temperature from sensors.
2. Accurately calculate the current altitude.
3. Beep at a frequency based on the rate of change in altitude (vertical
4. Act as a timer, with stopwatch like functionality as in start, stop, and reset (or
5. Attach to the pilot in a safe, usable, and comfortable fashion.
6. Record and save flight records such as altitude and total time of flight on the
7. Retrieve flight records make data viewable in a readable and helpful format.
8. Add compass functionality to the device.
There was an IEEE standard for recommended ambient conditions for test
measurements, however, it has been withdrawn and is no longer maintained or upheld. It is
titled 3-1982.
The project will be demonstrated through the use of video. I will take the device on
multiple flights and compare its results to the output of a commercial variometer. I will record
the footage with a Go Pro and show that it works in the environment it is designed for. I am
training to become a paraglider already so I have access to the sport. During development I can
take the project with me on my flights to test and debug its operation. This will be very
valuable in making sure it truly works under unexpected conditions due to weather.
The first steps in making this device, will be finding very low power components that can
all interface to the same microcontroller. The first component that will need to be determined
is the barometric pressure sensor. It will be the deciding factor for the technology needed on
the microcontroller and whether it’ll need to be I2C or SPI compatible.
Once those two components are determined, the display can be chosen. The display
will need to use the same voltage supply as the microcontroller and barometric pressure
sensor. It will also need to be easily visible and consume very little power.
After designing the overall circuit and determining the necessary power to drive the
device, the parts can be ordered, most likely through online vendors, or through using
connections the university has. With all components in, the device can be built, or at least a
prototype can be built and tested thoroughly. The microcontroller will need to be programmed
using C and thus a development environment will be needed.
Commercial Product references:
"Brauniger IQ Alto." Alti/ Vario @ Fly Sussex the Paragliding Experience. N.p., n.d. Web. 04 Nov.
2014. <>.
"IQ Alto." Brauniger. Brauniger Flugelectronic GmbH, n.d. Web. 04 Nov. 2014.
"Products Flight Instruments." Flytec USA // Flight Instruments. Web. 17 Oct. 2014.
R, Stefan I. "" Aircotec. Aircotec Flight Instruments GmbH, n.d. Web. 04
Nov. 2014.
"Variometers." Paragliding Online Store. Web. 17 Oct. 2014.
Component references:
"BMP180." BMP180. Bosch Sensortec, n.d. Web. 04 Nov. 2014. <>.
"QDSP 6064 Data Sheet." (n.d.): n. pag. Hewlett Packard. Web. 30 Oct. 2014.
Other Sources:
Marc Chirico, paragliding instructor for over 30 years, Seattle Paragliding.
Personal experience as a paragliding student.
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