Show IP 4 II I l lea I II TECH VOL OG Y YON I 4 q I VI q C CJ Q fa IA I T v o b v f o o q P Pao v L q I vp o THE g I 0 Ha 1 0 g VE 0 tb R Coming Soon Quieter Jet Engines How can jet engines be made less lees no noisy Jy Engine designers designers designers de de- de- de signers have wrestled with th this J question ever since the first jetliner entered service more than two decades ago Their research has haa paid off ocr Today's turbofan engines are much less leas noisy than the turbojets turbojet that ushered in the jet age But even quieter en engines gines gine are under development When the tint first McDonnell Douglas DC 9 Super 80 art cats Jt's conception below takes take to the air in 1979 it will be one of the quietest jetliners in the sky ky Its Ita pair of or turbofan turbofan turbo turbo- fan ran engines built by Pratt Whitney Aircraft will incorporate ad ads advanced noise low-noise technology that reduces the deep rumbling rumbling rumbling rum rum- bling sound at takeoff softens the siren siren like like watt wall and saw buzz whine during landing The new aircraft will have havea a noise root footprint print about 70 percent smaller than current current cur cur- rent twin twinjet Th This J means mean that takeoff and landing no noise Je will reach into much smaller maller areas of or the communities surrounding surrounding surrounding sur sur- rounding the airports served by the jetliner The plane will sound about half as aa loud loudas as current twin jets to people on the ground Interestingly the low no noise low noise Je turbofans are more fuel efficient efficient effi than current models and they produce less leas exhaust emissions They are also more powerful Pratt Whitney Aircraft Group of United Technologies gies Corporation reports that the new Dash engine can meet stringent federal noise and air pollution standards stand ards ands proposed for tor the years yean ahead Q c c. v S i c 1111 1 |