RealTechNews.com - Independent Tech

Thursday, November 11, 2004

NASA pushes for Mach 10 Flight
No, it's not an aircraft equipped with new Gillette razors. NASA is readying the X-43A aircraft to push the envelope to 7,000mph --a top speed that even John Force will never be able to break. There have been two previous attempts, one that had to be cancelled when the booster rocket went out of control and a second that hit 5,000mph. The flight is scheduled for November 15th, around 2:00pm PST.

Annoying Geek Note: The thing to keep in mind is that the speed of sound changes based on the medium it's measured in. The actual formula is a = sqrt [g * R * T], where a equals the square root of the ratio of specific heats g times the gas constant R times the temperature T. For example, at sea level, the speed of sound is approximately 761.7mph and 7,000mph is about equal to Mach 9.2. Take that up to 60,000 feet and that same speed is now Mach 10.6. Don't worry, Einstein is safe: The speed of light is 299,792,468 meters/second but the speed of sound is only 340.29 m/s at sea level. Hey, what do you want...? I had some free time.

# Permalink Posted at 7:06 AM 9 comments Email this Link

Comments on this Item:

OK Professor. What do you think, is this thing going to run right side up or upside down to stay in the atmosphere?

Besides, the biggest problem is maintaining a human life inside a vehicle going that fast. When the SR-71 is "slugging along" at Mach 3+ the windows are heated to approximately 350F! And nevermind the metallurgy challenges.

A less sophisticated vehicle that can simply gain enough altitude and then let the planet's rotation do all of the work would make better sense.

WRM

# posted by Anonymous 7:08 PM

You want it in a geo-stationary orbit and have the earth move 7,000mph beneath it? Wowouch! Wouldn't have to worry about blowing the leaves off my lawn.

# posted by Bill 8:13 PM

Not geostationary since that means your relative position over the surface never changes.

There's a reason for launching the shuttle from Florida: it's the closest point in the U.S. to the equator. Since the Earth's surface is moving at approx. 1,040 mph at the equator to the east the vehicle uses a percentage of that "free" velocity during its launch. Notice they always launch in an eaterly direction.

Missiles on the other hand get launched from the west coast and gain range towards Kwajelein by leaving the Earth's atmosphere (most of it anyway) and letting the planet spin below it.

The key to making a flight to Sydney from L.A. last only 2-3 hrs instead of 15 will be to create a vehicle that accelerates near vertically and sets up a ballistic trans atmospheric flight path towards its destination. The reason for leaving the atmosphere is "smoothness". If you've experienced turbulance on an airliner traveling at Mach .80, imagine the same at Mach 10.0!. The hard part has always been: how do you handle the logistics of dressing the passengers in pressure suits and pre-breathing them on 100% oxygen for at least an hour before the flight?

Rutan has made a big step in the right direction by developing a dual-skinned cabin that doesn't require the "suit", but that vehicle is only above 51,000' (altitude above which pressure suits are required) for a few minutes.

The other obstacle is the decel at the other end of the flight. Like John Force, the harder you accelerate in the beginning of the run, the harder it will be to slow down at the end. How to do that without causing physiological problems with the passengers?

WRM

# posted by Anonymous 8:18 AM

- Non-geostationary so the Earth moves below it, but at most that will only gain 1,000 mph (at the equator). Going that fast (above Mach 3) inside the atmosphere is a rough ride (and hot). Better to set up a ballistic flight path above 200,000 ft. to get a smoother ride.

Notice that this is an un-manned vehicle, mostly for program costs since it's very expsensive to keep a human alive inside this kind of vehicle where skin temps will be in the thousands of degrees.

So does it end up in the lagoon at Kwaj?

WRM

# posted by Anonymous 8:50 AM

Letting the earth spin below you may make sense if you are going from say New York to London, but what about when you want to come back? Do you need to go all the way around the other side of the planet?

# posted by Anonymous 9:02 AM

Good lord... No, they're building a giant catcher's mitt in Abu Dhabi. But it's all conjecture for me. I've never been on an airplane and I never intend to be --no matter how fast they claim it can fly.

# posted by Bill 9:44 AM

You can "fly" in either direction, but remember that there is an inertia penalty/reward/null for a particular course. Just like the airliners of today have to contend with wind direction, future "highspeed" vehicles will have to deal with the Earth's rotation

Right now the X-43A is missile technology. The future benefit will come from the propulsion technology by removing the need for an oxidizer tank in the vehicle. Look at the tank the Space Shuttle has to ride on to get into space! If you can use what's out there instead...

# posted by WRM 10:25 AM

Rotation. Gravity. Heat. Mach whatever.
MOOT!

Teleport!
http://news.bbc.co.uk/1/hi/sci/tech/3811785.stm

Yes, I'm kidding.
Yes, I'm wound up.
Yes, cuban coffee.

# posted by Terry 4:55 PM

Terry, we debunked this one back in June.
www.aliceandbill.com/2004/06/further-news-on-teleportation.html

# posted by Bill 6:22 PM

Post a Comment