A new airplane uses charged molecules, not propellers or turbines, to fly

[rangerrebew]

A new airplane uses charged molecules, not propellers or turbines, to fly

The nearly silent aircraft weighs about as much as a Chihuahua
By
Laurel Hamers
1:00pm, November 21, 2018
 

A newly designed airplane prototype does away with noisy propellers and turbines.

Instead, it’s powered by ionic wind: charged molecules, or ions, flowing in one direction and pushing the plane in the other. That setup makes the aircraft nearly silent. Such stealth planes could be useful for monitoring environmental conditions or capturing aerial imagery without disturbing natural habitats below.

The aircraft is the first of its kind to be propelled in this way, researchers report in the Nov. 22 Nature. In 10 indoor test flights the small plane, which weighs about as much as a Chihuahua, traveled 40 to 45 meters for almost 10 seconds at a steady height, even gaining about half a meter of altitude over the course of a flight.

https://www.sciencenews.org/article/airplane-charged-molecules-ionic-wind

[Elderberry]

https://www.nature.com/articles/s41586-018-0707-9.epdf?referrer_access_token=KEZSeS9bxGNqTY1QFysG9tRgN0jAjWel9jnR3ZoTv0O8jeS1MYPanuSpZ5pCO_VtrinMAGlKpSsB-vKEDmhUSaYBY_6sMQockhY-wvPVyezw9eVl-CN2w3XgbDJqu-tW_e6SL5WreEB9XrHJpi56Ppr8y-XBCiwjKZ91oOYS1k01dWJl3DdxU8HA1sOiU4joz0aMo0kMVpTFduSDiUQt_XQK8fHhLgQlO6qrVfXzq0s_D3RPeJstQCMZ-Kdbnjly&tracking_referrer=www.sciencenews.org

To produce a sustained thrust of 3 N at the 40 kV design point and estimated thrust-to-power ratio of 6.25 NwK^−1, a power system capable of delivering 500 W of output power was required, but at a very low weight. These weight constraints necessitated the design and construction of both a custom battery stack and a custom high-voltage power converter (HVPC) which stepped up the battery voltage to 40 kV. Our HVPC achieved a specific power of 1.2 kW/kg^−1, 5–10 times higher than conventional power supplies at this voltage and power.

This was enabled by careful converter topology selection, by design optimization and by operating at a high switching frequency between 500 kHz and 700 kHz to minimize the weight of the capacitors and the magnetics.

We performed ten flights with the full-scale experimental aircraft at the  MIT Johnson Indoor Track. Owing to the limited length of  the indoor space (60 m), we used a bungeed launch system to accelerate the  aircraft from stationary to a steady flight velocity of 5 ms^−1 within 5 m,and performed free flight in the remaining 55 m of flight space. We also performed ten unpowered glides with the thrusters turned off, in which the aeroplane flew for less than 10 m.

We used cameras and a computer vision algorithm to track the aircraft position and determine the flight trajectory. All flights gained height over the 8–9 s segment of steady flight, which covered a distance of 40–45 m. The average physical height gain of all flights was 0.47 m. However, for some of the flights, the aircraft velocity decreased during the flight. An adjustment for this loss of kinetic energy results in an energy equivalent height gain, which is the height gain that would have been achieved had the velocity remained constant. This was positive for seven of the ten flights, showing that better than steady-level flight had been achieved in those cases.