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

Oh great....

[QuietLagoon]

... now the pilots can aim the sonic boom to hit the area where their mother-in-law lives....

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.

Re:Oh great....

[justthinkit]

Indeed. This constant "boom" was given an unfortunately misleading name. It is more like an infinite Tsunami, able to sweep over and inundate everything.

If you live in a rural area....

[duckintheface]

becasue you love peace and quiet, well screw you. Is it ok to hit folks in low population areas with a shocking, loud noise. Helpful hint: NO, it is not.

Re:If you live in a rural area....

[YrWrstNtmr]

If you have two 'training bases' nearby, it's not sonic booms you're hearing. Engine noise, afterburner, yes. Sonic booms? Almost certainly not.

Re:If you live in a rural area....

[hawguy]

I see you know nothing at all about it. I have experienced a sonic boom from the ground and it's no big deal.

I suggest you learn about the subject by reading and not watching movies.

It's no big deal when it happens once a month, but if you live under a busy flight path and have to hear the rumbling of sonic boom hundreds of times a day (and night) then you may not be so understanding.

Re:If you live in a rural area....

[0123456]

If it's no big deal, they're working on a non-existing problem, right? There's no need to avoid the populated areas at all.

Yes, exactly. Sonic booms from airliners have never really been a big problem, because airliners want to fly as high as possible to minimize fuel consumption. Most of the damaging booms are from military aircraft at lower altitudes.

But, unfortunately, saying 'it's no big deal' isn't good enough for the NIMBYs.

Re:If you live in a rural area....

[PPH]

if you live under a busy flight path

You are probably living under an approach or departure path. In which case aircraft won't be flying supersonic. The Concorde needed several hundred miles to decelerate below Mach 1 and usually reached subsonic speeds before entering an ATC area (a flight path).

Aircraft are increasingly moving away from point to point established routes. These date from the days when cross country navigation was done between radio beacons with direction finding receivers. Now, its based on individually planned routes which can be spread out, reducing the impact on any one point on the ground (and spacing flights apart for safety as well).

Re:If you live in a rural area....

[ZorglubZ]

Ummm... Sonic booms from airliners have always occured over the ocean, because the only commercial airplane with supersonic capability was the Concord. All other sonic booms from airplanes have all been from military aircraft.

I know they're real motive

[AndyKron]

I think they're developing it so the Israelis will be able better able to piss off the Palestinians.

Paraphrasing the Simpsons

[Anonymous Coward]

becasue you love peace and quiet, well screw you. Is it ok to hit folks in low population areas with a shocking, loud noise. Helpful hint: NO, it is not.

Sonic booms and noise pollution - well all pollution - should be where it rightfully belongs; in poor people's backyards.

Re:I was in the path of some low-level sonic event

[jfdavis668]

Was this in California? That's called and earthquake.

Why pilots??

[Anonymous Coward]

Seems like something which could be done by a 'back room' computer when the flight path is being generated. At that point, you could modify the flight path to put the sonic boom where you want.

Re:Why pilots??

[Hognoxious]

Luddite! I bet you think putting GPS on trains is overkill too!

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

[Greyfox]

Back in the 80's at Robins Air Force Base, the fighter jets would drop a sonic boom on the area every week or so. They weren't any worse than a distant thunderstorm and significantly less bad than a nearby thunderstorm. I'm frequently surprised at all the hysteria over them, especially considering how often they occur over most of the continental USA (Never.) In the top 1000 things to worry about or be annoyed by, that shouldn't even be on the list.

Re:Cost bigger issue than sonic boom

[rossdee]

"To make supersonic flight possible over sea or over land, the cost must come down"

I think you are missing the word 'commercial' in that statement.

For military flight, cost isn't such a big issue.

Re:Cost bigger issue than sonic boom

[magarity]

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

Well duh, ANY engine noise is "energy wasted on shaking the air" as any engineer can tell you. A 787 is nice and quiet compared to other airliners but it's still burning fuel to shake some air. It is a legit question to ask if it is *economical* to shake the air at the sonic boom level.

Re:Cost bigger issue than sonic boom

[PPH]

For military flight, cost isn't such a big issue.

But the detectability of supersonic aircraft is. So this is probably the customer at whom this technology is targeted.

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.

Re:Cost bigger issue than sonic boom

[Solandri]

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.

Out of curiosity, how old are you? I was a kid in the 1970s. 1970s jet engines were LOUD. When we were playing during recess and a jet plane passed overhead at 30,000 ft at the right orientations (certain directions were noisier), we basically couldn't hold a conversation without yelling. That's how loud they were. They were a great way to demonstrate that sound was slower than light because it was so damn loud it was obvious exactly where the sound was coming from. Your ears could indisputably pinpoint the sound as coming from several hands-breadths behind the plane.

The concerns about the Concorde's sonic boom being even louder were very real. The planes we have today where you often don't even notice they're passing overhead are a poor point of reference, and a testament to how great a job the engine manufacturers have done at reducing noise.

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.

Total energy isn't as important as the spectrum. If all that energy is directed into a narrow low-frequency band, it'll be a lot noisier even at a lower energy level, moreso at the lower frequencies (the atmosphere absorbs higher frequencies more rapidly). In fact that's mostly what the engineers have done to make today's jet engines quieter - changed their noise profile to spread that acoustic energy over a broader spectrum of frequencies and into higher frequencies. The scalloped cutouts on the trailing edge of newer engine cowlings does exactly this.

Re:Cost bigger issue than sonic boom

[thrig]

"The supersonics are comingas surely as tomorrow. You will be flying one version or another by 1980 and be trying to remember what the great debate was all about." -- Najeeb Halaby, administrator, FAA.

Uh yeah. About that.

Re:Cost bigger issue than sonic boom

[careysub]

Thanks for all your calculations, but you entirely neglect auditory acoustic response issues, or the fact this energy is coming exclusively in rapid rise impulses.

There is more direct information in this readily available. We read here that the
"Concorde's sonic boom noise level was 105 PLdB. The PLdB that researchers believe will be acceptable for unrestricted supersonic flight over land is 75, but NASA wants to eventually beat that and reach 70 PLdB."
The measure PLdB is "perceived level of decibels" which takes into the account that impulsive, rapid rise sounds appear louder to humans. A 105 dB sound is a very loud sound to anybody. There would be hundreds, perhaps even thousands, of supersonic flights coast-to-coast a day if this became commercial. If you were under a common flight corridor, you might hear one of these every few minutes all day long.

The NASA article discusses though the fact that aircraft design can lessen sonic booms, and that is real key to making this a viable transcontinental technology.

But where we really need supersonic flight is on trans-Pacific flights! Where are the hypersonic trans-Pacific airliner projects these days?

Re:Cost bigger issue than sonic boom

[Grishnakh]

Some of the hysteria is probably because a very low-altitude plane flying supersonic can probably break windows, so people are worried about that. Of course, we're talking about higher-altitude planes here, so that isn't really justified.

The other worry is probably the frequency of the booms. One boom a month isn't a big deal, but what if they decide to make a frequent flight path over your house in the suburbs or in the country? Now you've got sonic booms every day, throughout the day. No one wants that.

They don't occur often over the continental USA because they're illegal (except for military planes), and these days because there's no supersonic passenger planes left. The Concorde was the only one, and it was limited to trans-Atlantic routes over water because of the restriction on sonic booms. I don't think it's unreasonable for people to be worried about something that isn't a problem now because of legality and current technological state; these things can and do change. Texting-and-driving 20 years ago wasn't a problem either, but now it is; it would have been helpful if someone had worried about it a little more. Drunken driving wasn't a problem 120 years ago, but again maybe someone should have worried about it and done something before it turned into a big societal problem.

Personally, I don't even see why supersonic travel should exist for passengers. It uses insane amounts of fuel, and even if that problem is fixed, it's unlikely it'll ever be as fuel-efficient as subsonic flight. No one really needs to get around that fast. If you don't like 14-hour flights over the Pacific, then don't do them; stay at home instead, or choose a closer vacation destination. Maybe eventually we'll avoid this problem altogether with some kind of sub-orbital vehicle which is both fast and fuel-efficient, but I'm not holding my breath.

Re:Cost bigger issue than sonic boom

[Grishnakh]

Hahaha, that's like the opposite of that patent office guy circa 1900 who said that everything that could be invented had already been invented.

Re:Cost bigger issue than sonic boom

[dotancohen]

We also get a sonic boom every few weeks (Beersheba Israel, and we got them when I lived in Haifa as well). It's less noise than a car going by, and lasts for less time. I'm sure if you buzz a shack at Mach 2 the boom would be deafening, but typical combat aircraft at typical don't-SAM-me altitudes don't make much noise. I've also had the pleasure of hearing the double sonic boom from the STS orbiters coming in to land over Florida. I don't know how fast they were going, but even those booms, though a bit louder I think, were no big deal.

Re: Cost bigger issue than sonic boom

[tandavanadesan]

They can be very loud. I was on an airshow when an English electric lightning flew supersonic at low level over the crowd (a practice now banned). That hurt!

Re:Cost bigger issue than sonic boom

[Greyfox]

Mythbusters tested that. The guy had to be flying something crazy like 1000 feet in order to cause any damage like that. Very few people sane enough to be allowed to fly a supersonic aircraft would ever actually fly one that low at those speeds. Plow into a bird and you wouldn't even know how you died.

Re:Cost bigger issue than sonic boom

[i.r.id10t]

I enjoyed my very first hangover on an early morning flight on a 727 "Whisper Jet". Whisper my ass...

Re:Cost bigger issue than sonic boom

[Grishnakh]

Probably not much, however, who wants to live someplace where they have to hear the boom of a massive lightning storm day in and day out? Thunderstorms are noisy, it's true, but for most people they're a fairly rare event.

Re:Cost bigger issue than sonic boom

[Grishnakh]

I seem to remember that plane literally leaking fuel when it was on the ground.

Re:Cost bigger issue than sonic boom

[140Mandak262Jamuna]

Thanks for the correction. I missed it by a factor 1000 in power estimate. But I also lowballed the area by orders magnitude. Plane at 6 miles altitude, sonic boom energy is spread over a conical surface of base radius 10 km, area of at least 300 sq km. Wind energy goes as the cube of velocity, (squared in the kinetic energy term, and linear in the mass flow rate term). So at most it will be compared to a breeze of 12 or 13 mph rather than 10. But that is about all.

Still feeling like a chump for missing the energy estimate by a factor of 1000.

Re:Cost bigger issue than sonic boom

[jersey_emt]

That is correct. The heat generated from traveling at > Mach 3 caused significant expansion of the (mostly titanium) body, so there were gaps between body panels. This wasn't an issue, because the SR-71 would refuel just after takeoff before proceeding on its mission.

Re:Cost bigger issue than sonic boom

[magarity]

that quote is a myth; the guy actually said more along the lines of so many new things have been invented that he wouldn't be surprised if there were less new inventions in the future. which is a far cry from saying nothing new would be invented.

Because we are all sonic snowflakes

[TheRealHocusLocus]

âoeOur team of experts will investigate how best to show this to pilots in the cockpit and develop guidance to most effectively modify the aircraftâ(TM)s flight path to avoid populated areas or prevent sonic booms.

Yes. On Sunday it will do this. But Monday thru Saturday this technology will be used to test methods for waging Cymatic Warfare... in which fighter planes slave their autopilots to a central computer that flies them in passes towards a target zone from several vectors, such that the sonic boom interfaces-to-ground converge at the same instant. We have yet to see what might happen as standard building materials are subject to this type of harmonically amplified sonic energy. By Saturday afternoon we'll know.

Because there is no such thing as a single-use technology.

Re:I was in the path of some low-level sonic event

[X0563511]

Muscle memory.

Saw a Falconview plugin that did this

[gatkinso]

About 10 years ago or so.

Re:I was in the path of some low-level sonic event

[Grishnakh]

It's probably muscle memory. I do something similar: many times when I try to type "ratio" I'll add an extra 'n' for "ration", which I of course then need to backspace over. And of course, auto spell checkers think it's just fine since it's still a valid word.

Dubious calculations

[jmichaelg]

Your prodigious display of math is all for naught since you've essentially proved 1=2.

I grew up in the early 60's when sonic booms were part of the background along with Duck and Cover. Nuclear war was just around the corner, or so we thought, and jets routinely generated sonic booms. Sometimes they'd sound like distant thunder and other times they'd rattle the house. Those were far louder, and more objectionable, than your putative 10 mph breeze.

Thankfully, they tapered off towards the end of the 60's as the Air Force realized people *really* didn't like being rattled and those same people objected to Congress. Since the later controlled the budget, the Air Force cut back on high speed overflight over the cities.

Booms weren't just domestic issues. NOVA interviewed a British Consul who was sitting in a tent in the Middle East discussing trade issues with his Middle Eastern counterparts. The Concorde flies overhead and the resultant boom startled all the conferees. The Consul said one of the men pointed at the sky and said "Concorde." at which point the Consul realized another trade issue had just been raised.

Some of those booms were anything but quiet and they sure weren't FUD as you assert.

Re:Or prevent it?

[Anonymous Coward]

I agree, a silent jet engine would be a huge advantage. Why aren't they working on this?

Re:I was in the path of some low-level sonic event

[PPH]

I live with them every day. I'm along the approach path to SeaTac and aircraft pass overhead at about 6000 feet numerous times a day. No problem.

What gets exciting is that this is also (sometimes) the approach path to either Boeing Field or Paine Field. And occasionally a test flight comes over at 1500 to 2000 feet if they are in trouble. Gear down 15 miles from the airport is usually trouble as in "We f*cked up the hydaulics installation again! No flaps!"

I though we solved this

[__aasehi2499]

There was a breakthrough a few years back where they found how to prevent the bow shock from forming in the first place. Did that die in R&D?

Stupid idea

[ChrisMaple]

A device in the cockpit to tell the pilot where to go, so as to minimize sonic boom impact? This is a one-time job, map out good regions to fly through, done.