New Study: “Could Wind Blow eVTOL Industry Out of the Sky?”

A recent study look­ing at the mete­o­ro­log­i­cal con­di­tions eVTOLs may face while fly­ing through and above cities offers a chill­ing warn­ing. Sud­den and reg­u­lar wind gusts can not only form around city build­ings, but could be strong enough to desta­bilise a fly­ing taxi with the poten­tial of knock­ing it off course, even lead­ing to a poten­tial crash.

As any new indus­try devel­ops, so poten­tial prob­lems man­i­fest. For exam­ple, anoth­er recent study has shown the sound of an eVTOL may be mag­ni­fied while tak­ing off or land­ing at a ver­ti­port or heli­port due to an effect when noise bounces off the ground.

“eVTOL Pro­pellers Loud­er Over Ground,” Say Researchers From Bris­tol Uni­ver­si­ty

So, the wind prob­lem comes as no sur­prise, espe­cial­ly as heli­copter pilots have faced sim­i­lar dif­fi­cul­ties over many decades when fly­ing through or above moun­tain­ous or hilly regions.

A recent paper by Aus­tralia-based ‘RMIT University’s Uncrewed Air­craft Sys­tems (UAS) Research Team’, flagged up “the wind prob­lem” after mea­sur­ing the sud­den gusts that form around city build­ings. 

Lead RMIT researcher and Aero­space Engi­neer, Dr Abdul­ghani Mohamed, who’s stud­ied wind gust dynam­ics for over a decade, says this phe­nom­e­non needs to be ful­ly under­stood and addressed before city skies embrace fly­ing taxis and drones. 

Mohamed com­ments that low-fly­ing air­craft are at risk from gusts because they land and take off at low speed. The RMIT research revealed sud­den wind can pose sig­nif­i­cant safe­ty chal­lenges for air taxis and drones in less than a sec­ond.

As a result, these air­craft will need more pow­er for land­ing or tak­ing off in cities com­pared with an air­port or an open space. This is a major prob­lem for elec­tric-pow­ered air­craft when land­ing, if the bat­tery charge is deplet­ed after a 30 minute or so jour­ney. Par­tic­u­lar­ly, if it is a deliv­ery drone giv­en its light weight.

Mohamed explains, “These air­craft need pow­er­ful motors that can rapid­ly change the thrust gen­er­at­ed by the pro­pellers to rapid­ly force the vehi­cle back on-course, a process which requires more ener­gy.”

He con­tin­ues,  “Reg­u­la­tions and cer­ti­fi­ca­tion need to specif­i­cal­ly address safe oper­a­tion when tra­vers­ing build­ing flow fields.” And argues that site-spe­cif­ic wind sim­u­la­tions and mea­sure­ments are essen­tial to iden­ti­fy haz­ardous regions.  “As we deter­mine the loca­tion of ver­ti­ports, we also need to deter­mine haz­ardous regions to avoid. This will enhance safe­ty and reduce inter­rup­tion of a fleet due to wind con­di­tions.”

In some coun­tries like Aus­tralia, it is not clear whether this respon­si­bil­i­ty falls under the juris­dic­tion of the air reg­u­la­tor, CASA, or the Bureau of Mete­o­rol­o­gy. How­ev­er, air taxis will need to be pro­vid­ed with weath­er infor­ma­tion at much high­er res­o­lu­tion and faster rates than cur­rent­ly pos­si­ble. This is crit­i­cal for flight plan­ning.

RMIT Research Team (Dr Abdul­ghani Mohamed in Pink Shirt)

Mohamed con­tin­ues, “Pur­pose-built ver­ti­ports mean we can inte­grate geo­met­ric design fea­tures to reduce haz­ardous flow con­di­tions from occur­ring, where the mar­gin of error is much low­er than at air­ports, where large air­craft can tol­er­ate far stronger gusts. We don’t have that flex­i­bil­i­ty with air taxis in cities.”

He goes on, “Exist­ing build­ings can also be repur­posed as ver­ti­ports, but may require mod­i­fi­ca­tions to improve the aero­dy­nam­ics near the land­ing pads. The effec­tive­ness of such design fea­tures can be assessed through either scaled exper­i­ments in wind tun­nels or through full-scale mea­sure­ments.”

Mohamed con­cludes, “Exten­sive wind flow map­ping at full-scale will no longer be daunt­ing in the future. We are con­tin­u­ing to devel­op our wind sens­ing drones – a swarm of drones instru­ment­ed with wind anemome­ters – to very accu­rate­ly map around large infra­struc­ture.”

The RMIT researchers say they will con­tin­ue study­ing this wind phe­nom­e­non with an explo­ration of dif­fer­ent build­ing shapes that may min­imise adverse effects. The team are also look­ing at the sen­si­tiv­i­ty of light-weight air­craft to gusts and tur­bu­lence, as well as flight-sta­bil­i­ty tech­nolo­gies. 

This research was con­duct­ed in col­lab­o­ra­tion with the Uni­ver­si­ty of Mary­land and Lehigh Uni­ver­si­ty and fund­ed by the US Air­force Office for Sci­en­tif­ic Research and DSI Group. 

The Full Report

https://www.mdpi.com/2504–446X/7/1/22

(News Source:https://remit.edu.au)

(Top Image: “Will Voloc­i­ty Face Windy Con­di­tions over Paris Next Year?”)

(Oth­er images: RMIT)