Rockwell Collins To Develop Cockpit Display To Show Sonic Boom Over Land

An anonymous reader writes: Under contract from NASA, Rockwell Collins is developing equipment to let pilots of supersonic craft know where a sonic boom will be produced. The hope is to make supersonic flight over land practical. Flying higher widens impacts but lessens intensity. “In order for supersonic travel over land to happen, pilots will need an intuitive display interface that tells them where the aircraft’s sonic boom is occurring,” said John Borghese, vice president, Advanced Technology Center for Rockwell Collins. “Our team of experts will investigate how best to show this to pilots in the cockpit and develop guidance to most effectively modify the aircraft’s flight path to avoid populated areas or prevent sonic booms.”

Comments

Re:Oh great....

[Anonymous Coward]

You know that the sonic boom is a constant thing, trailing behind a plane flying super-sonic, right? This will just help pilots by telling them when it's alright to go super sonic.

Cost bigger issue than sonic boom

[140Mandak262Jamuna]

To make supersonic flight possible over sea or over land, the cost must come down. Without reducing the cost it makes no sense to worry about sonic boom, or figuring out ways to show the pilot where it hits the ground and its intensity.

Also the sonic boom issue was more FUD by Boeing, Douglas and Lockheed than the real issue. Back in the 80s, before the oil crisis, these companies wanted to stop British Aerospace and Aerospatiale from establishing a bridgehead at the luxury travel sector using Corcorde and its derivatives. But thankfully the Arab oil shock stopped Concorde.

Think about it, the total energy of all the shock and sonic boom is equal to amount of jet fuel burnt. During cruise at Mach 2.05 each Olympus 593 was producing around 10,000 lb of thrust, equivalent to 36,000 horsepower per engine.[18] Two engines, 72000 HP. Or 54 kilowatt, or 54,0000 joules/sec. If all of it ends up as sonic boom, (neglecting skin friction) you are going to spread 54,0000 joules every second over several square miles. Compare this to peak solar radiation 1000 joules per square meter. OK that is purely thermal but this is mechanical. So let us take 10 mph wind. 16kmph. 4.44 m/s. Over 1 sq m cross section, mass flow rate is 4.44 * density of air/second. Air is 1 Kg/m^3. So it is 4.44 kg. 4.44 m/s velocity. Works out to kinetic power (power, not energy because we are using mass flow rate, not mass) of 0.5*mdot*v^2 = 22 joules/sec. This is per square meter. or 22 watts per square meter. 22 million watts per square kilometer. Let us round it up to a nice 100 million watts for several square kilometers. Compare that to 54 kilowatt, total maximum possible power output of those two turbojet engines. 100,000 kW for 10 mph wind vs 54 kW for Concorde. Our eardrums and instruments are sensitive enough to pick up the sonic boom over 10mph wind, but thats about it. Barely detectable. Sonic booms deafening people, cracking buildings and killing birds are all FUD.

But cost... That is no mean thing to solve. In supersonic flight the energy needed to overcome the drag created by the shock wave is so high, there is no easy way to reduce the energy consumption. Only way to bring down the cost is to bring down the cost of fuel. The only way to make fuel cheaper is for the world to switch to non-fossil fules in such a large scale the oil industry collapses and oil falls to something like 5 dollar a barrel ( 2015 dollar not 1978 dollar).

Re:Cost bigger issue than sonic boom

[PPH]

Think about it, the total energy of all the shock and sonic boom is equal to amount of jet fuel burnt.

Um, there's a lot of air being heated as well. In fact, that's the point.

Or 54 kilowatt, or 54,0000 joules/sec.

More like 54 * 10^6 joules/sec

Our eardrums and instruments are sensitive enough to pick up the sonic boom over 10mph wind, but thats about it.

Go back and crank in that 10^3 factor. It's not that quiet. But then again, since our ears and perception are logarithmic, it's not that bad compared to other sounds.

It's also a function of altitude. If you can keep supersonic aircraft at or above 60,000 feet (and there are reasons other than noise for doing so), the shock wave energy is spread out over a greater area and attenuated.