Private Rocketplane Test A Success 283
HobbySpacer writes: "XCOR
announced the success of the first phase of flight tests
for the EZ-Rocket. In the most recent flight, Dick Rutan fired both of its rocket engines to take off and reach a speed of 160knots and an altitude of 6200 feet. The vehicle is a Long-EZ kit plane modified to hold
twin 400 lb thrust rocket engines fueled by isopropyl
alcohol and liquid oxygen. The project is not aimed at a homebuilt EZ-Rocket but will demonstrate safe and reliable rocket propulsion.
The primary goal is development of reusable launch technology that leads next to a high altitude sub-orbital rocket vehicle for
space tourism,
rocket
racing (e.g. vertical drag racing at air shows) and the
X-Prize competition."
Unit conversions (Score:3, Informative)
6200 feet = 1890m
400 lb = 1779N
A cool feature for slashcode would be automatic unit conversions.
Re:umm, what about balloons? (Score:2, Informative)
True. On the other hand, there are definite advantages to getting above a high percentage of that pesky thick layer of air that seems to blanket this planet.
* There's a lot of aerodynamic drag associated with the passage through the dense atmosphere at low altitudes Ever notice the Shuttle and other rockets throttle down at the "max Q" (maximum aerodynamic pressure) point? That (inefficient) action is necessary to limit the forces so the vehicle won't break up.
* Although the altitude balloons can reach is much, much less than that of orbit, there is still a measurable advantage in necessary delta-v (velocity increment needed to reach orbit) from a high-altitude launch. I haven't look at the exact numbers in years, but it's on the order of percents--not insignificant when dealing with the tight margins inherent in launching.
Re:umm, what about balloons? (Score:5, Informative)
Rotary Rocket gone (Score:3, Informative)
The big problem was that the new engine concept didn't work out, and using off the shelf engines doomed the thing to suborbital flight, for which there is no commercial market.
Re:umm, what about balloons? (Score:3, Informative)
http://www.friends-partners.org/mwade/lvs/rocko
They were invented by Dr. Van Allen and some of his associates. They were only for sounding rockets, which explore the upper atmosphere but don't go into orbit. If you want to go into orbit, you still need a lot of horizontal velocity so the rockoon is not as handy for that.
article text (Score:2, Informative)
Re:umm, what about balloons? (Score:2, Informative)
Re:Unit conversions (Score:3, Informative)
The whole idea of metric is that we should put all of our eggs in the one basket, so that people with certian brain defects would not be able to understand it. I found little logical in it to understand what people see so wonderful in it, and I have studied it for thirty years now.
Umm, no. The beauty of metric, or rather the more modern form of metric called SI (Systeme Internationale) is that:
a) multiples of a unit are always in base 10, so it is obvious that 27km = 27000m, and it is just as simple to write that in scientific notation (i.e. 27km = 2.7x10^4m) - you try telling me what 27 miles is in feet without reaching for a calculator
and b) there is a small set of measured base units (there are 7 - metres, kilograms, seconds, amperes, kelvins, moles and candelas) and every other unit used throughout science and engineering is directly derived from these base units without any fudging
Quite apart from the obvious benefits for calculation, it also makes things much easier to understand in your head - you only need to know the size of the 7 base units to be able to have some idea of exactly what each derived unit means. Also, if you are sticking to SI notation to the letter, it is plain from the name of the derived unit exactly how it is derived from the base units.
Really, it is perfectly logical, and a heck of a lot simpler to learn than the old Imperial or Imperial-derived systems, where there were about 3 times as many different base units. Science has adopted SI worldwide, partly for its ease and simplicity, and yes, partly because scientists want to be able to understand each other. In most countries, engineers have also adopted the system for similar reasons, and even the general populace understands most of it thanks to everyday things being measured in SI units or multiples of - masses in grams or kilograms, volume in litres, distances in metres or kilometres.
Anyway, in SI Units...
160 knots = 82 ms^-1 (metres per second) :)
6200 ft = 1900 m (yes, this one was right
400 lbf = 1800mkgs^-2 (meters per kilogram per second, aka newtons)
All conversions rounded to 2 significant figures... now, who's going to be the first to complain about the use of significant figures? ;)
Another dude in the mix (Score:2, Informative)
Everything he's worked on and gone through is pretty damn interesting, worth the read if you haven't heard of him.. He's set to launch in May of next year
URL for me262 replica project (Score:2, Informative)
Wrong! (Score:2, Informative)
The total energy efficiency of an orbital rocket can be defined as the potential energy of the empty rocket in orbit divided by the chemical energy in the propellants. Even here rockets are not that bad.
If you have a hydrogen powered rocket with a specific impulse of 4300m/s and a total delta-v of 9000m/s, your mass ratio is 8.109, so the propellant weighs 7.109 times as much as the empty rocket. But the empty rocket has a specific kinetic energy of about 30 MJ/kg, whereas the propellants only have a specific chemical energy of 11MJ/kg. The total efficiency is thus 30/(7.109*11)=0.38. Not too bad, eh?
The reason rockets are still so expensive is that most current rockets are direct descendants of ballistic missiles where cost was not important. And the shuttle is a f***ing joke.
regards,
tuttle
Re:Pointless (Score:5, Informative)
Got any ideas? Once you're at the edge of the atmosphere, you're pretty much limited to using a self contained reaction motor.
Ground laser launching relies on superheating air, plus it's only been used to shove vehicles directly up, so it's basically a really cool but expensive way to replace July 4 bottle rockets. A more viable alternative is turning beamed EM into electricity then powering magnetohydrodynamic motors that superheat air, but you still have that pesky problem that you are relying on an atmosphere to get your speed.
You could accelerate the vehicle in a rail gun or rocket sled until it reaches orbital velocity while it's still on the ground. Ballpark figure, at a (barely) survivable 20g, you'd need a 150km track to reach the 7.73km/s orbital velocity of a typical shuttle mission, ignoring air resistance. Except you can't ignore air resistance, because at 7.73km/sec at 1 atmosphere, you'd burn the vehicle to a toasty crisp.
Even if you postulated antigrav, you still need to generate lateral acceleration to achieve orbital velocity, which again requires a self contained rocket, or an atmosphere.
A beanstalk (space elevator)? Heck, maybe we've already got the technology to do it, but we're not going to, not for a long, long time.
So, really, if you've got any ideas about what to use as an alternative to rocketry today, let's hear them. I'm fresh out.
Re:Pointless (Score:2, Informative)
Re:Rocket Racing! (Score:3, Informative)
Hydrogen / oxygen rockets also produce water and excess hydrogen. Alcohol / ocygen rockets leave a few other things similar to auto exhaust, but not really worse.
Solid rockets leave some bad stuff, and some propellants are truly nasty, like nitrogen tetroxide and hydrazine, but those are also much more expensive, so wouldn't be used in a cost effective program.
John Carmack
Re:Pointless (Score:3, Informative)
It merely has to replace the first stage, and that only requires a few miles of track, an upwardly sloping mountainside, and a few G's of acceleration. One the ship leaves the mouth of the catapult, it's moving fast enough for a very small fuel tank to kick it all the way to orbit -- not to mention the fact that at mountain height, it's past a goodly chuck of the atmosphere pretty quickly.
It's surprising how little ship you need to achieve orbit once you get rid of the first few miles and get some speed buildup. The ship is SMALL.
A catpult would prolly use maglev, be pretty cheap once the thing is built, and only require electricity to operate instead of rocket fuel. And it is reusable to a ridiculous degree.