why don't airplanes go faster than they did 20 years ago?

Answer 1

Well I can probably answer the military side at least.
For air-to-air, or air-to-mud combat, speed isn't as important as agility. That is an umbrella term that includes acceleration, and the ability to sustain large instantaneous and sustained "G". Most aerial engagements happen at 380-540knots. there's various reasons for this, but basically, it's because at higher speeds, it's very difficult to maneuver your aircraft properly.
Also, pure speed burns A LOT of fuel, which reduces the time you can loiter. Historically, right after not seeing the guy who blows you out of the sky, getting nailed while trying to disengage is a leading killer of aircrews.
I SUSPECT that on the civilian side, it's because for most travellers, getting there a few hours quicker is not as important as getting there for a reasonable fare. The Concorde is a perfect example of designers missing this economic reality. Concorde tickets would cost up to twice as much as a first-class seat on BA or Air France. Only people who absolutely needed to get across the pond in 3 hours, or wanted the status of flying on the Concorde, wanted to pay that. Even so, they NEVER made any money.

Answer 2

From WWII on up through the Cold War, the most prominent theory when it came to combat aircraft was that if it could fly higher and faster, then that made it better. And for the most part, it was. If the good guy's bombers could fly higher than the bad guy's persuit planes could reach, then they would be safe. If the good guy's persuit planes went higher and faster than the bad guy's bombers did, then they could defend against them.

This theory remained true all the way through most of the Cold War. In the 1960s, the US developed the XB-70 Valkyrie - a high altitude, mach 3 capable bomber (which never made it into service). The USSR responded to this threat in 1970 with the MiG-25 Foxbat, which was a massively powerful mach 3 capable interceptor. The US came back again in the mid 70s with the F-15 Eagle, a mach 2.6 air superiority fighter. Each was designed with the idea that they would have to climb high and fast in order to intercept the other guys high, fast jets.

And then somewhere along the line, we all kind of caught on that all this wasn't really necessary. We don't need SR-71 type high altitude reconnaissance anymore - we have satellites to do that. And we don't need mach 3 bombers anymore when we have ballistic and cruise missiles that will get the job done without exposing a flight crew to hostile fire. And therefore, we don't need Mach 2.5+ interceptors to catch them. Most air-to-air combat is done BVR now (beyond visual range) with the use of advanced radar and missiles. While fighter pilots are still trained in aerial combat, dogfight scenarios are typically very much subsonic. You can turn your jet a lot faster and tighter at 400kts than you can at 800.

The next generation of combat aircraft, we are seeing, are stressing what engineers believe will be more important features, such as stealth, and the ability to supercruise. That is to say that it can fly at supersonic speeds (the F-22 boasts Mach 1.7+) without the use of an afterburner, which saves a TON of gas, increases the time the aircraft can stay in the combat area, and (in theory) saves the taxpayers some green.

On the civilian side, it's primarily about economics. It's about how fast can you go on the least amount of fuel. Modern day high-bypass turbofan engines are extremely efficient in the thrust they produce for what they weigh and consume in terms of fuel, and while the Concorde program certainly proved there is a safe way to travel faster, it also proved to be a costly one. And then there is also the noise polution problem to deal with as well. The Concorde had to wait until it was out over the ocean before going supersonic for just this reason, which is yet one more strike against it in terms of its efficiency. It would have been even faster across the pond had these kinds of resrictions not been in place. I've read somewhere (don't recall where at the moment, sorry) that there is still research and development going on in the areas of SSTs (supersonic transports), with special emphasis in the area of noise reduction. We'll just have to keep an ear out for that in the future I guess.

Whether or not SSTs will ever make an eventual comeback into commercial aviation, I'm not decided either way. As for the military side of things, I think that low-visibility and supercruise technology will be the future, at least for the next decade or two. After that, well... we can only guess what the future holds for both military and civilian aviation. We've proven long ago that if we had the need to go fast, we can. The X-15 went Mach 6.72 in 1959, but what use is that to anyone other than for research and experimental purposes? I am quite confident that we will continue to see gradual and slight increases on the airspeed indicators of current and near-future aircraft designs as engine efficiency and wing designs continue to improve. However, until the day such a need or desire arises for astounding speed to once again come to the forefront of modern aviation technology, I doubt we're in for any dramatic developments.

Answer 3

Some do and some don't. There are several reasons for this, the cost of fuel not being the least. Commercial (and military under certain conditions) don't like to be flying around much over 600 knots due to that very noisy thing called "sonic boom". The craft them selves have come a long way since Chuck busted the sound barrier, that new scram jet can boogie off at better than 6 times the speed of sound.

Answer 4

In the case of commercial aircraft, the manufacturers are nudging cruise speeds up ever so slightly by improving wing design. But the speed of sound hasn't changed, so the effect of drag divergence is almost completely unmitigated. Drag divergence is the rapid increase in drag as flight Mach number approaches 1.0 . It's due to wave drag, the drag encountered as the airframe pushes a shock wave through the air. This happens even when an airliner is traveling at subsonic speed because the velocity of air moving over specific spots on the wing and fuselage is higher than the free stream velocity.

In the business aircraft realm, look at plans for supersonic business jets by Aerion, Gulfstream, and Sukhoi, to name just a few. These companies are moving resolutely toward some significant gains in business jet performance through thoughtful combinations of propulsion systems and aerodynamics.

So the short answer is: technically they are going a little bit faster, but in reality it's just not economically feasible because drag increases sharply near Mach 1. If there were a pressing economic need to go faster, it would happen.

So I guess the shorter answer is: because no one wants it badly enough to pay for it.

Answer 5

Airplanes of today is not that slow. Well they don't go faster than they were 20 years ago because the airplanes a becoming bigger to accommodate more and more people.

Answer 6

These are all really good answers.
Fuel costs and sonic boom are the main reasons, and there is no real reason to go that fast, even Bill Gates time isnt worth that much money.
The truth is, the normal person will never need anything better than what we have now. You can literally fly around the world and be home in one weekend.
There are a few supersonic aircraft in the works, nothing incredible, but they will be able to achieve mach 1.3.-1.6 for a realistic cost. One of them can carry 8 people, and to a business, if you can get 8 executives 1000 miles in an hour for 5000 bucks, its worth it. It makes business sense.

Answer 7

PLENTY OF GOOD ANSWERS POSTED.

But what I read not too many months ago is that there are aircraft engine designs on the drawing boards which feature a jet engine powering a large ducted propellor. It's really an extension of fan-jet technology.

Really retro-grade, but it gets much better fuel efficiency, at the cost of a minor REDUCTION in speed. Cross-country flights would take 10-to-15 minutes longer. But ticket prices would go down.

Answer 8

Some do.
Improved aircraft airframe design, and hi-bypass engines.
For example, 727 were over built with strength ratios of 6.5+ to 1 (1 pound of aircraft could carry a load of 6.5 pounds) resulting in heavier airframes.
A 757 would only have about 1.5 to 1 ratio, or 1.5lbs. of load for every pound of aircraft.
This has helped reducing over all aircraft weight. Less weight for the engines to proppell forward, means more engine power is now utilized for top end speed.
But don't expect any jet with fixed ducting to surpass the speed of sound. They won't work, that is why you see military jet's ducts changing during operation. The laws of traveling gasses reverse after passing through the speed of sound, so will the intake and exhaust ducts of these engines inorder for them to countinue to operate..

Answer 9

Supersonic flight is a whole different ball-game when it comes to aerodynamics, which is basically what you are referring too.

Additionally, to double the speed of the aircraft for instance you need much more than double the power, therefore it becomes progressively more difficult to squeeze that extra bit of airspeed out of each machine every time it gets a little faster. There have been improvements over the past 20 years in airspeed (among many other aspects of flight of course), but they are seemingly small for this reason.

Answer 10

The engines use air, pistons compress it, propellers move it.
Jets use turbines, same thing, scram is good. hardly any moving parts, just dynamics, then there are materials to withstand the forces and the skill to go faster after the engineers and manufacturers figure how to go commercial and make money.
Then the govt and worldwide limits of traffic control. What a mix.