Kite Inflator Specification
[This document is a work in progress.]
The kite inflator is a device that monitors and sets the inflation pressure of the kite. It will also serve as a general purpose data logger and transmitter for sensors such as an altimeter, temperature sensor, and GPS.
Physical, Environmental, Performance
1. max size: ?
2. max weight: ?
3. kite attachment method: ?
4. splashproof, but not submersible
5. external power switch and on/off display
6. normal use constitutes the motor valve operating for 25% of the time
7. must run for 12 hours of normal use on a full charge
8. reliable radio range of 100m on the water
We learned a number of lessons since the development of the first kite inflator PCB, including the need for a pressure release valve. The latest revision is much smaller overall, provides better electronic isolation of the pump motor, and more convenient positioning of connectors.
We tested the inflator on a kite in the shop on Friday. The overall performance of the pump, pressure release valve, and radio link exceed our requirements. The firmware crashed after several hours of operation, however, so we will need to fix this bug and ensure that any future errors do not result in a deflated or exploded kite. The test showed that the inflation rate is 1.4 psi/hour and deflation rate is 5.6 psi/hour with a 40 sqm kite in the pressure range of interest. This is fast enough to handle small leaks, temperature-related pressure changes, and minor inflation adjustments for performance optimization.
A few weeks ago we did some testing of the kite inflation system with a new motor, electronics, and firmware. Everything has been looking good and we are looking forward to testing it on a boat or lifting kite soon.
In the attached plot, the green line indicates the target pressure, which is changed remotely using the web interface to cause the system to inflate and deflate the kite. The red line shows the measured air pressure. The measurement is somewhat noisier than the actual air pressure because the sensor is attached to the same tube as the in intake and outlet. The improved firmware filters this noise enough to keep the actual pressure within the kite quite stable.
The electronic kite inflator, which we sometimes refer to as the kite Inflation Management System (IMS), is now ready for additional field testing. The device is designed to monitor and regulate the pressure of inflated kites. A Zigbee radio link is used to transmit pressure and status to the ground and to receive pressure setpoint commands. The inflator is integrated into the web-based logger interface, which allows us to monitor and control the kite pressure from any smartphone.
The latest version of the inflator uses a smaller and more robust PCB, and has a pressure release valve. Previously, the device could only inflate the kite, and had no way to release air if necessary. With the new release valve, the […more]
Jamie has augmented our kite inflation controller, which monitors a kite’s inflation levels and maintains a designated psi by inflating the kite further, in case of a leak or temperature change, for example. The new electronics add precise pressure measurement, a radio link to the ground, and remote pressure control. In the photos, the system is inflating a kite section to 8 psi. Our smaller kites take higher inflation pressures, up to 9 psi, whereas the larger kites take lower pressures, 2-3 psi. This system is splashproof, but not waterproof, which is sufficient now that our launch and retrieval procedures largely keep the kite out of the water.
The graph shows the pressure as the small kite section is inflated […more]