Words by Sophie Chua, Patent Tech­ni­cal Assis­tant, Mew­burn Ellis

The com­pos­ites indus­try has estab­lished itself as an essen­tial part­ner to aero­space man­u­fac­tur­ing. The need for advanced com­pos­ites in the eVTOL mar­ket is even more acute as light-weight­ing is essen­tial for elec­tric vehi­cles. Not only is there a need for these air­craft to have lighter com­po­nents, but their designs need to also com­prise few­er com­po­nents.

What makes the eVTOL indus­try so excit­ing for the com­pos­ites indus­try is the extent to which com­pos­ites can play a part in eVTOL air­craft struc­tures; on aver­age approx­i­mate­ly 70 per cent of an eVTOL aircraft’s weight is com­pos­ite mate­r­i­al, com­pared with a Boe­ing 787 which has approx­i­mate­ly 50 per cent of its struc­ture made from com­pos­ite mate­r­i­al.

Ther­moset resins are cur­rent­ly the most used resin type in the aero­space indus­try. Giv­en the race to get eVTOL vehi­cles cer­ti­fied as quick­ly as pos­si­ble, man­u­fac­tur­ers are turn­ing to proven mate­ri­als as a first step, rather than leap­ing to brand new inno­va­tions straight­away. It is not sur­pris­ing that more than 90 per cent of eVTOL man­u­fac­tur­ers are enter­ing into cer­ti­fi­ca­tion with ther­moset-rich plat­forms.

How­ev­er, we are like­ly to see a tran­si­tion to the use of ther­mo­plas­tics, par­tic­u­lar­ly fibre- rein­forced ther­mo­plas­tics. Ther­mo­plas­tics facil­i­tate sig­nif­i­cant­ly lighter-weight vehi­cles at high­er pro­duc­tion rates due to their reduced cycle times.

Fur­ther­more, the inher­ent recy­cla­bil­i­ty prop­er­ties of ther­mo­plas­tics improve sus­tain­abil­i­ty, an ongo­ing ini­tia­tive of the com­pos­ites indus­try. Although the tran­si­tion is expect­ed to be grad­ual, key com­pos­ite mate­ri­als sup­pli­ers such as Toray are already mar­ket­ing ther­mo­plas­tics for eVTOL appli­ca­tion.

Ver­ti­cal Aero­space is an exam­ple of a man­u­fac­tur­er mak­ing sig­nif­i­cant use of ther­mo­plas­tics. Their flag­ship air­craft VX4 has com­po­nents like rotor blades, bat­tery enclo­sures and brack­ets made using ther­mo­plas­tic prepregs.

The pro­to­type has suc­cess­ful­ly under­tak­en pilot­ed test flights and is now in the next stages of the flight test pro­gramme. Ver­ti­cal have built an expe­ri­enced team and part­nered with big indus­try play­ers such as Rolls Royce to help them to achieve cer­ti­fi­ca­tion and scale-up of their pio­neer­ing air­craft.

The demand for com­pos­ite mate­ri­als is expect­ed to sig­nif­i­cant­ly increase as plans for eVTOL vehi­cle man­u­fac­tur­ers to scale-up pro­duc­tion take shape, and is esti­mat­ed to reach $673 mil­lion in 2030 (up from an esti­mat­ed $36.2 mil­lion in 2024).

With the shift towards ther­mo­plas­tics and a need to devel­op ther­mo­plas­tic man­u­fac­tur­ing solu­tions for larg­er struc­tures, a re-eval­u­a­tion of the cur­rent sup­ply chain may be required to keep up with the demand.

Clear­ly, the eVTOL and com­pos­ites indus­tries are on an upwards tra­jec­to­ry, and it will not be long before we are able to take a com­mer­cial flight aboard an eVTOL air­craft. In such a rapid­ly evolv­ing indus­try, it will be fas­ci­nat­ing to see the way in which new inno­va­tion dri­ves advances, and the way in which intel­lec­tu­al prop­er­ty around those inno­va­tions might allow one or two com­pa­nies to ‘fly high­er’ from a com­mer­cial per­spec­tive.

The indus­try has already cre­at­ed oppor­tu­ni­ties for sev­er­al man­u­fac­tur­ing and sup­ply part­ner­ships who are now incred­i­bly close to deliv­er­ing a new era of mobil­i­ty.