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Towards Silent Supersonic Planes
Roland Piquepaille writes "There is no longer a single commercial supersonic airplane since the retirement of the Concorde last year. And even during its years of glory, the Concorde was not a commercial success, mainly because it was not allowed to cruise at supersonic speed over land. Why? Because of the sonic 'boom' which arises when you break the sound barrier. Now, a joint program between NASA, the military and the aerospace industry wants to remove, or at least reduce, this sonic boom, by changing the shape of supersonic planes. It seems to work. After a 'nose job' on a Northrop Grumman F-5E, about a third of the pressure released when breaking the sound barrier has already been suppressed. This overview contains more details. It also includes a photograph of the modified Northrop Grumman F-5Ea aircraft flying off the wing of the F-15B research testbed aircraft. [Note: Previous results were reported here by Slashdot in last September.]"
Nope. The Boom is omnidirectional. In fact, the downward part of the wave is aided by the increasing atmospheric pressure.
"If we let things terrify us, life will not be worth living."
- Seneca
There was a smaller article like this in Popular Science a while back, and since I am very interested in planes and aerospace, it now is on my wall. I'll type it down for you guys, I'ts actually very interesting...
All Zoom, No Boom
Teaching an F-5E Tiger how to tiptoes.
There's nothing more dramatic than a supersonic jet streaking overhead; and nothing more annoying than the bone-rattling sonic boom it leaves behind. The boom really consists of two bangs caused by the N-wave in the planes wake, with rapid pressure rises corresponding to the nose and tail. Northrop-Grumman hopes that by tailoring a F-5E Tiger with a longer nose an modified tail, and tinkering wiht its body and wngs, the boom can be transformed into a smooth, inaudible hump. Engineers got the idea from research that goes back to the 1970's. Today's computers, which make it possible to model airflows up to 200 yards from a plane, were required to put the theories into practice. Tests being next august. --Written by Bill Sweetman.
I don't know exactly when it was published, but it shows that this is really no new idea. On an interesting side-note, my uncle worked for McDonald Douglas before they were bought out by Boeing, and actually was a systems engineer for the Coherent Readar systems for the F-5F. When I told him about this he thought it was one of the coolest things he'd ever heard.
~I was playing poker with tarot cards the other night. I got a full house and that same night five people died. True story.
Most supersonic aircraft require afterburners in order to go faster then sound, and afterburners are incredibly voracious consumers of fuel. I think that one of the other very important innovations is the "Supercruise" ability, seen on aircraft like the F-22 Raptor. This allows the aircraft to maintain supersonic speed for extended periods of time in a low power setting, and this in turn is just as vital for cheap, commercially viable flights. I hope that advances in sonic boom suppression will also work well with the necessary designs for supercruising, and that we may all be able to take advantage of such flights within the next 2-3 decades. If both aren't taken into account, and designers come up with plans that make for an either-or choice, it could mean supersonic planes will still be relegated to the relatively wealthy.
Nah
Ryu could take him hands down every time - why? He need a charge up of about 1 - 2 seconds to pull off those moves.
Really good players could negate the charge up easily enough but that means that for just a moment they are blocking, and blocking means thrown. If they tried to hit you to keep you from throwing then they lost the charge.
I will say this though, the kick was amazing because he traveled forward and up (unlike ryu's dragon punch which only went a little forward) it was easy to click someones head, knock them over then land close enough for some serious ass pounding.
Ryu > *
End of story.
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"If we let things terrify us, life will not be worth living."
- Seneca
To go off on someone for getting an airplane wrong.. and getting the airplane wrong yourself.
The plane in the top right is definitely an F-15 as is stated in the caption. The side-mounted air intakes are a little hard to see, but are obviously different from the bottom-mounted air intake of the F-16, however the giveaway is the tail. F-16s have a very differently shaped tail than the F-15, and it's an F-15 tail in the picture.
That plane is used for training purposes to be the agressor, it looks like one of the Navy OpFor planes from Palomar. The us military uses mocked up soviet equipment, or sometimes even real soviet equipment to train against.
I used to have a cool sig, back when I cared
The bottom left photo is not a F-20. There were just 1 or 2 made, and they are owned by Northrop, not the Navy.
The F-5 in the lower left is owned by the Navy. The reason that it has the Red Star painted on it is that it's an agressor plane used by the Top Gun dogfighting school.
If tits were wings it'd be flying around.
The reason the Concorde was an economic failure was not the sonic boom - it was a failure because of the enormous fuel consumption per passenger, as well as the enormous maintenance costs per passenger. This was true even though the airlines purchased the Concordes for $1 apiece, and there was no purchase cost to amortize.
It's created constantly by supersonic flight. It's a byproduct of the air pressure in front of the plane being extremely high, steadily decreasing as you head back to the tail, and a sharp rise behind the tail when the pressure snaps back to normal.
This is why there are two booms from each aircraft. The first one from the pressure wave preceding the plane, and the second from the posterior wave.
"If we let things terrify us, life will not be worth living."
- Seneca
Riiiight...
Top right - F-15
Center - Modified F-5
Bottom left - Standard F-5, painted in TigerShark livery.
The F-20 is just slightly different frm the F-5, as evidenced by the extra bulk around the tail root.
This particular F-15B from NASA has a different nose. More pointed than a line model. That is why you were confused.
Air Force uses an F5 variant called the T-38. You see the Shuttle pilots flying these around, and they are used as the chase planes on landing.
Good aircraft. They are supersonic, nimble, stable, and are good for teaching multi-engine techniques.
I have something in common with Stephen Hawking...
The sonic boom is constant. It is because the sound source is travelling than the sound itself, thus the wave doesn't have a chance to decay before it is regenerated by the travelling object. The individual waves add up to form the sonic boom.
When a jet flies by, you would hear two booms: one at the front when the nose pierces the air, and another at the rear when the air fills the void behind the aircraft (in theory its polarity would be opposite that of the first).
Read about it here: Doppler Shift
-Billco, Fnarg.com
Possibly, however you said " it was a failure because of the enormous fuel consumption per passenger,"
I took a few minutes to demonstrate that the cost of fuel was not, in itself, an especially large component of the running cost of the aircraft.
ALso, BA's accounts show that the Concorde operation was profitable prior to the crash.
The 'boom' is a continuous shockwave that occurs as long as the vehicle is at supersonic velocities. This is why these planes have generally not been allowed to fly at supersonic speeds over occupied land.
Basically there would be a violent rumble on the ground over the entire length of the plane's flight corridor. The idea is to reduce or remove entirely the shockwave coming off the vehicle surfaces.
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That third plane is also an F-5 Tiger. Look at the fairing between the tail fin and the fuselage as well as the cockpit design, both are exactly the same. You'll notice that the sonic boom is only changed below the plane, the top is not changed at all sinec nobody really cares about the boom above the plane.
The main boom is the one I was describing, and as far as I can tell, it was accurate. At least the Wikipedia seems to agree with me:
"If we let things terrify us, life will not be worth living."
- Seneca
If Boeing's 7E7 project turns out to be substantially less successful that Airbus's 380 project, Boeing might not have the capital or the time to design a new cvil aviation platform--preferring instead to suck on the Pentagon's teat.
Airbus thinks that the airlines will continue to consolidate their hubs. If so, they'll ditch the aging 747 platform for A380.
Boeing thinks that airlines will add more nonstop routes between secondary cities-- e.g Detroit to Shanghai. If so, they'll probably buy more 7E7's, as unlike the older Boeing planes, the Dreamliner is substantially more fuel efficient that the Airbus offerings.
1. The plane's Olympus 593 engines were serious fuel guzzlers and made a tremendous amount of noise on takeoff, especially with the afterburner (known as reheat in Europe) running. Also, they definitely don't meet today's standards for jet engine exhaust emissions, either.
2. The plane's range limited itself to flying between New York City and London/Paris--and even then the plane require priority handling by air traffic control during its flight.
3. The plane's carrying capacity was too low for its size.
4. The plane--because it had to fly at Mach 2-plus--needed very careful design for heat-dissipation reasons.
I think for tomorrow's SST's, the technologies now available will do the following:
1. By carefully shaping the entire plane, this drastically reduces the pressure wave buildup that causes the sonic boom in the first place. By limiting the top speed to around Mach 1.7 when the plane flies at altitude the sonic boom may be barely audiable or not audiable at all.
2. The use of modern aerospace materials means the plane can be quite a bit lighter, which means you can consider larger passenger and/or cargo loads. Also, because the plane is limited to Mach 1.7 top speed there is less pressing need for heat-resistant external surfaces.
3. Jet engine technology improvements since the 1960's will allow for SST jet engines that are very quiet on takeoff and landing (meeting even the upcoming ICAO Stage IV noise standards), yet operate efficiently at supersonic cruise. Also, improved combustor designs will drastically reduce the exhaust emissions that plagued the Olympus 593 engine. Because the top speed is only Mach 1.7, it may be possible to apply the supercruise jet engine technology used on the F-22 Raptor's jet engines, which means less need for afterburner (reheat) operation and lower fuel burn.
In short, we are very close to developing a Mach 1.7 SST seating 200-250 passengers that could fly over 6,300 nautical miles, be very quiet on takeoff and landing, not be an environmental hazard from jet exhaust and have sonic boom that is almost non-existent. Imagine being able to fly from San Francisco to London at Mach 1.7--we may be talking about cutting nearly 40% the flight time compared to a Boeing 747! =)
The speed of sound at 30,000 ft above sea level is about 678 MPH
So at top speed thats: 89% the speed of sound (damn near 90%)
And At cruising speed it's: 83%
Pretty Close.
The article refers to Concorde as the only supersonic passenger aircraft. That is not the case; the russian Tupolev TU-144 ran a short lived passenger service in the late '70s.
:)
Of course it was even less efficient than the Concorde, but it did exist
http://www.themeparks.ie
No, a T-38 is a two-seater. That 3rd plane simply looks like a unmodified F-5 fighter jet.
The aircraft looks to be a non-modified F-5E.
Paint scheme make it look like a Soviet Aircraft, making the aircraft most likely to come from the Nellis Airforce Base where the Red Flag exercises are done.
A standard 747 holds 300 people...
Not so. A standard 747-400 (most recent model) holds 416 people in a three-class configuration. Charter 747s with all-economy seating can hold 500 or more.
All seats on Concorde are first class.
No, they were Concorde class; a step above first class.
Aviation fuel is not taxed, much to the disadvantage of the environment. If it was taxed at the same rate as automotive fuel is in most of the world, flying would be priced where it should be, i.e. out of reach of most people, and there would be substantial environmental benefit.
Because there are much less airplanes than there are cars. If plane emissions ever start to get anywhere even NEAR that of cars, you can bet that they start to get taxed more.
Jet aircraft have done far more damage to the ozone layer than anything else.
Links, please. Planes emit mostly CO2 and Nitrogen oxides just like anything else that burns fossil fuels, NO's do destroy ozone, but nowhere as efficiently as chlorine, and only supersonics fly high enough for their emissions to make it into ozone layer. Now that concorde is gone, only supersonics are military aircraft, not much hope trying to prevent those from flying with taxes.
On lower altutides that most jet aircraft fly at, NO's actually stimulate ozone production, of course on the low altitudes it's a pollutant of it's own and a greenhouse gas as well.
I had a chance to visit the British Airways Concorde at the Museum of Flight at Boeing Field in Seattle, WA and I don't know if I'd call those seats first class other than there are only two seats on each side of the plane. To protect the seats they've covered each side of the interior over with curved pieces of plexi-glass and the remaing isle is very narrow. In looking at the seat size it looks smaller than a first class or even business class seat on a widebody jet but since I could only look at the seats and not try them out I can't do a real comparison. I guess it would be tolerable though given the much short travel time in flying on the Concorde.
The other thing that struck me about the Concorde was how small the interior is and the door is quite low going into the plane. I had to duck as I entered the plane to keep from hitting my head on the doorway.
I don't have much knowledge of aircraft certification, but I do have some knowlege of certification processes in other industries.
The difference is in where the burden lies. Apparently (taking the parent post at face value), in the past manufacturers had to prove to the FAA's satisfaction that a design was safe. Now, they just have to give the design to the FAA, and the assumption is that it will be certified unless the FAA proves that it is unsafe (therefore the burden of proof is on the government).
Obviously this is a lower standard - since those most able to find flaws in the design are the designers, who work for the manufacturer who wants their design approved.
Honestly, I cannot vouch for how the FAA certification process really works, but in most industries that are regulated the burden of proof is on the industry - to prove that they are operating within the regs. The regulatory agency merely audits their processes and looks for signs of things being out of order. Industry is supposed to police itself, while the govt polices the police. This has the benefit of shifting the safety costs to the industry - where they are ultimately reflected in the prices of goods (which makes sense - if planes cost a fortune to make safe it should be reflected in the cost of plane tickets, so that consumers can take a train if it makes more sense).
I'm always open to alternative systems if they actually work...