Would rocket-flight in deep space be possible?

Status
Not open for further replies.
D

drazaxa

Guest
I am merely curious, would flight in deep space actually be possible?<br /><br />From what i know; a rocket to the moon for example: pushes against the very thin atmosphere in the space between the moon and earth. And because of no gravity, high speeds are easy to perform. Just like a boats propellar pushes against the water to exert the boat forwards, and an airplain pushes against earths atmosphere.<br /><br />But in a vastness of deepspace millions of lightyears away from any galaxy, where you'll find a few atoms every mile...<br /><br />Would rocket flight be possible? lol<br />Or maybe dark matter would act as a matter to push on?<br /><br />thx
 
V

vogon13

Guest
Where to begin..................<br /><br /><img src="/images/icons/frown.gif" /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
D

drazaxa

Guest
I see! thank you.<br /><br />One last curiosity on the matter, wouldthe photons of a powerfull enough lightsource/wave emitter be able to act as a thruster in deep space? <img src="/images/icons/laugh.gif" /> <br /><br />[edit:] maybe flying hovercrafts could be made to float with powerfull wave emitters :p no one steal my ideas lol
 
C

CalliArcale

Guest
<blockquote><font class="small">In reply to:</font><hr /><p>From what i know; a rocket to the moon for example: pushes against the very thin atmosphere in the space between the moon and earth. And because of no gravity, high speeds are easy to perform. Just like a boats propellar pushes against the water to exert the boat forwards, and an airplain pushes against earths atmosphere. <p><hr /></p></p></blockquote><br /><br />That's exactly the same misunderstanding the general press had back when Goddard was doing his experiments, so don't feel bad! Very smart people have made the same mistake.<br /><br />Truth is, a rocket doesn't need to push against the air. (Neither does a jet engine, actually.) So what is it pushing against? We all know that every action must have an equal and opposite reaction, so how is the rocket going forward?<br /><br />Rockets and jet engines belong to a class of engines called "reaction motors". This means they use exactly that Newtonian principle to move forward -- equal and opposite reaction. But they're not pushing against the ground or the air, so what is the action that is producing the reaction of pushing them forwards? Basically, it's the force of propelling material out the back of the engine. The reaction to that is that the engine moves forward (along with anything attached to it, like an airplane or spaceship).<br /><br />Have you ever fired a gun? That will make it much easier to understand. If you haven't fired a gun, just watch it on TV and you should get the basic principle. The way a gun works is that a tiny amount of explosive (black powder) is detonated in a confined space. This propels the bullet out of the gun. But that's not all it does. It also propels the gun back, in a phenomenon technically called recoil. The action is the bullet being forced out of the gun. The reaction is the gun kicking backwards. The gun had no fixed object to push against, but the law still applies -- if it throws the bullet forwards, there has to <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
D

drazaxa

Guest
Oh<br /><br />Thanx callie,<br />Yes the 'screw' method is what i was thinking about, sucking from front and exerting behind, like screwing through an atmosphere. I thought of a rocket merely using fuel in replacement of sucking from infront. <img src="/images/icons/smile.gif" />
 
A

averygoodspirit

Guest
A jet engine uses a few aerodynamic principles. If you observe the individual blades of a trubo fan jet engine, they are not only pitched relative to the hub they are each attached to, they are also airfoil shaped like the wing of an airplane. This airfoil shape creates a lifting force so the engine is lifted forward as air passes over the blades. The pitch of the blades causes air to be sucked or pulled into the engine more efficiently incorporating a screwing effect. This creates a lower dynamic pressure in front of the jet engine and a higher dynamic pressure behind the engine. It is the difference in dynamic pressures that also serve to move the engine and everything attached to it (aircraft) through the medium (air) in which it is operated. For example, at mach 3, 90% of the propulsion of the engine of an SR 71 is from the differential of dynamic pressures and 10% is from specific impulse power. In other words, it sucks itself through the air much more than it pushes itself through the air. <br /><br />A rocket engine uses two basic principles. One is thrust caused by the amount of ejected material and the second is specific impulse which is the velocity of the ejected material. It is the product of these two factors that give the amount of power the rocket engine can generate. <br /><br />The problem with using conventional, chemical rocket engines for long distance space flight, like interstellar flight, has to do with efficiency. They simply use too much fuel and chemical fuels are massive. It requires a lot of energy to move all that mass. <br /><br />Ion propulsion engines are more efficient than chemical fuel engines because they use less fuel to produce the same amount of energy and they offer higher specific impulse power. The amount of thrust ion engines produce is far less than a conventional, chemical fueled rocket engine so it takes longer to accomplish the same task. It’s worth it in the long run however due to their increased efficie <div class="Discussion_UserSignature"> </div>
 
V

vogon13

Guest
I appreciate that. <br /><br />Sometimes the task seems so overwhelming....... <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
A

averygoodspirit

Guest
Stevehw33:<br /><br />Who's advice are you refuting? I don’t think anyone has stated that rocket engines don’t work in space. <br /><br />The use of rocket engines to move things around in our solar system, via Sir Isaac Newton’s third law of motion, is one thing, while interplanetary space travel is quite another. For that we will need my newly internationally patented Warp/Hyperspace Drive engines. <br /> <div class="Discussion_UserSignature"> </div>
 
A

averygoodspirit

Guest
Drazaxa:<br /><br /><font color="yellow">One last curiosity on the matter, would the photons of a powerfull enough lightsource/wave emitter be able to act as a thruster in deep space?<br /><br /><font color="white"> Yes. It is one of many sources of propulsion that is on the drawing board. Like a solar sail it works by incorporating radiation pressure. <br /><br /><font color="orange"> The screw is a variation on the inclined plane. Airplane propellers also incorporate principles of lift, helicopter rotors are another kettle of fish altogether<br /><br /><font color="white"> Actually they’re not. The rotor of a helicopter uses two aerodynamic principles. One is pitch or angle of attack, like a screw or the propeller of an airplane. More advanced prop driven aircraft have variable pitch propellers that are automatic or pilot controlled to improve efficiency at variable airspeeds and/or altitudes. <br /><br />The second principle is lift from an airfoil shape like the wing of an airplane. An airfoil incorporates Daniel Bernoulli’s Principle. Daniel Bernoulli was an eighteenth-century Swiss scientist who discovered that as the velocity of a fluid increases, its pressure decreases. A wing or helicopter rotor is curved on top and flat on the bottom. This means that air, which is a fluid, must travel faster over the top of the rotor than along the bottom. This creates a decrease in pressure on top of the helicopter. One way to describe this decrease in pressure is to call it a differential pressure. This simply means that the pressure at one point is different from the pressure at another point. For this reason, the principle is sometimes called Bernoulli's Law of Pressure Differential. Essentially this means that the airplane or helicopter lifts up because there is greater pressure below it than on top of it.<br /></font></font></font></font> <div class="Discussion_UserSignature"> </div>
 
S

Saiph

Guest
well...pressure differentials <i>and</i> standard newtonian "angle of attack" pushing the air. Both are there. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
N

nexium

Guest
Yes light sources can propel space craft in deep space, but the propulsion is barely detectable, unless the light source is very powerful and/or the space craft has very large surface area such as a light sail craft. Neil
 
A

a_lost_packet_

Guest
Wow.<br /><br />A greater than two-year old thread, resurrected from the dead.<br /><br />I'm not complaining though. Some really good posts in this thread including the new ones. I am glad to see that even after two years, someone finally address the issue of light-propulsion as well. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
 
Status
Not open for further replies.

ASK THE COMMUNITY