attack that might be able to go after the helicopter. reporter: experts say the sound suppression technology makes some differences. first, what a standard blackhawk helicopter sounds like. this has a rihythmic kind of woosh-woosh sound. now we ll show you what a stealth helicopter sounds like. experts say this sounds a lot more vague. you may not be able to tell whether this is another vehicle entirely or helicopter. you may not be able to tell whether the helicopter s moving towards you or moving away. experts say the small wings, called stabilizers, are also unique to this chopper. they re usually at a hard right angle but these are angled off, analysts say, to avoid radar detention. the chinese have a huge interest in this technology. they re developing a stealth fighter jet called the j-20 which they ve already test flown. contacted by cnn, a chinese
sequence start. sequence start. t minus 25 seconds. discovery s on board computers have primary control of the vehicle s critical functions. 20 seconds. t minus 15 seconds and the sound suppression water system has been activated. we have a go for main start. up and ready. 3, 2, 1. zero. booster ignition and liftoff of discovery. blazing a trail to scientific discovery for the space station. roll discovery.