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Private Rocketplane Test A Success
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."
160knots = 296 km/h
6200 feet = 1890m
400 lb = 1779N
A cool feature for slashcode would be automatic unit conversions.
"The primary issue with getting into orbit isn't going up, its with going sideways at around 17,000 mph."
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.
The main reason is the FAA. If you want to be a high alt attempt, you need to file a lot of paperwork concerning your flight plan and risks to populated areas/foreign airspace. In theory, you could get approval for an orbital shot from two places in the USA (Black Rock and Alaska,) if you have a self-destruct device on board. Note that a self-destruct doesn't make the rocket vanish, it just puts the debris in a safe zone. Now, if you want to float to 120,000 feet before launch, your debris zone is about the size of the Pacific Ocean. You don't get approval, end of story.
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.
I think you are refering to a "rockoon".
o n. htm
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.
JP Aerospace "America's OTHER Space Program" is doing this very thing. They used balloons to carry a launch platform and rocket to 26,000 ft where they launched the rocket. Now they're currently working up to being able to launch from 100,000 ft.
Not sure if it's been posted yet, but a guy out in Oregon is also working on something related to this.. Goes by RocketGuy
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
Looks like they are building five of them and plan to fly one this year. http://www.stormbirds.com/project/
I do not know what kind of efficiency you mean, but in terms of energy efficiency rockets are actually very good. A rocket engine transforms about 90% of the chemical energy of the propellants to kinetic energy. This is excellent.
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
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.
If you were blocking sigs, you wouldn't have to read this.
No, actually a ramjet is way more efficient than a rocket. A really good rocket motor gets an Isp of just over 400. (A little more if you feel like using F2 or ClF5 or other really nasty stuff, but nothing that dramatic.) A ramjet gets around 3000. It's a lot simpler than the rocket, and it doesn't have to carry it's own oxisizer, so it stands to reason. On the other hand, it doesn't work in space, and it needs to move a a pretty good speed before it starts working at all. /August.
"An object declared as type _Bool is large enough to store the values 0 and 1." -- 6.1.2.5, C99 standard.
The rockets we are currently firing use hydrogen peroxide, which produces nothing but water and oxygen in the exhaust. Not even the most rabid greenie could argue with that.
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
The "rocket sled" (actually a linear induction motor used as a railgun of sorts, also called a mass driver by Gerry O'Neill and company, and first dubbed a "catapult" by Heinlein and something totally else by Clarke) doesn't have to accelerate the ship to orbital speed. That's ludicrous.
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.