h a l f b a k e r y
non-lame halfbakery tagline
idea:
add, search, annotate, link, view, overview, recent, by name, best, random
meta:
news, help, about, links, report a problem
account:
Browse anonymously,
or get an account
and write.
Login
Create account.
|
|
|
Please log in.
If you're not logged in,
you can see what this page
looks like, but you will
not be able to add anything.
Why not have a rocket that provides sinusoidal g's, like a series of pulse detonations, and then have a rocket seat have heavy suspension/damping on it!? This way, the rocket could effectively experience the equivalent of many g's on average*, while the astronaut would be feeling very little g's on average.
I envision a slinky seat, where the astronaut sinusoidally goes from the front to the back of the spaceship with a large damping coefficient.
It would be like the rocket is going 0-50 g's in 10 seconds, while the astronaut felt only 10 g's since he went from the front of the to center of the rocket, and then the rocket going back to zero g's in another 10 seconds, while astronaut feels another 10 g's in going the rest of the way, from the center to the back of the ship...then while the ship is at zero g's, the explosion booster recharges for the next detonation, the astronaut gets to the front by the seat at a couple g's, and then the process starts over again with another 20 second detonation/deflagration cycle.
*Note... the average that I speak of is over the detonation/deflagration time period of 40 seconds, and doesn't include the reload time when the ship stops accelerating but the astronaut is still accelerating.
Need that narrow lunch window...
Virtual_20Car
...right over here. [pertinax, Apr 16 2007]
Annotation:
|
| |
I really hope this would work. I know nothing of the physics or physiology involved but I really really hope they wouldn't get in the way. This is just such a funny image. <Puts on large curly moustache and spring> Boing <Takes off large curly moustache and spring> |
|
| |
???? The average acceleration of both astronut and rocket is the same, over the long term. |
|
| |
Keeping one's lunch down could be a significant problem when riding a spring with a 10 g amplitude. |
|
| |
This would work best with a very long rocket, possibly a kilometer. The astronauts would sit in the middle and traverse the length of the rocket back and forth. I love it. |
|
| |
This would be good for long term acceleration - colonizing far planets etc. The pulse detonations would be the sort of acceleration a nuclear bomb ship would provide. |
|
| |
//the rocket could effectively experience the equivalent of many g's on average, while the astronaut would be feeling very little g's on average. //
This is, of course, wrong. |
|
| |
Very wrong, indeed. One way to look at it is to realize that, upon final engine shut-down, the rocket and the astronaut are going to be together still. They must have had the same average acceleration to have started together and to finish together. [-] |
|
| |
What is it about space ideas? Every now and then someone posts something that's completely and fundamentally wrong, but it sounds good so it gets a lot of votes. |
|
| |
It's not space that intrigues, it's the slinky. |
|
| |
That's what I mean. It's a great image, but it just won't fly. So it gets votes. |
|
| |
But there's some confusion in the writing. The author may just be proposing that any pulse rocket should have springs on the seats, which is so obvious that it's been done in science fiction even when it wasn't needed. |
|
| |
But what he writes, accidentally or not, is that the average acceleration of a rocket and its passenger be different, which is a violation of the laws of physics. You could use springs to smooth out a bumpy rocket to where the passenger feels the tolerable average acceleration of the rocket, which is obvious, but you can't make him feel less than that. |
|
| |
How about this instead: Make a carnival ride from a big "spaceship" mounted on rollers, with the chair-on-rollers and slinky inside. Then slam the spaceship back and forth on its rollers. The rider will remain mostly in place, watching the walls go back and forth, and the slinky going sproing. |
|
| |
It will look like the idea posted, work right here on Earth, and not violate any laws of physics. It will also illustrate that, at the end of the ride, the "rocket" and the passenger have averaged the same acceleration and ended up at the same place. |
|
| |
The stuff about divergent rates of acceleration is bunk but this seems more useful than that would suggest. If the rocket were to leave Earth with a huge burst of speed then stop accelerating this mechanism would allow that burst to be dampened and extended. The astronaut would continue to move within the rocket for a lot longer than the rocket accelerated. My guess about //the rocket could effectively experience the equivalent of many g's on average, while the astronaut would be feeling very little g's on average// is that [quantum_flux] is referring to the point when the rocket ceases to accelerate. Since the astronaut would have a lot of sproinging left to do but the rocket would be weightless the g-force sustained by the rocket would at that point be far greater than that sustained by the astronaut. The eventual averages would match but this would allow the astronauts to take their punishment in smaller doses over a longer time. |
|
| |
Assuming we neglect earth's gravitation, and make some other simplifying assumptions (like a really big rocket ship), if we can demonstrate it for this bizzare case, then surely a less halfbaked case for a real rocketry system could be demonstrated: |
|
| |
if: ds =v dt; dv=a dt; then: ds= a dt^2 |
|
| |
if a_a=98.1 sin(t*pi/40) represents the astronaut's motion for 40 seconds, starting at v=0, then the astronaut is moving 2498.1 m/s (relative to CM of earth), and has traversed a distance of 49962.0 m |
|
| |
and if a_r=490.5sin(t*pi/40) represents the space ship's motion for 40 seconds, starting at v=0, then the spaceship is moving 12490.5 m/s, and has traversed a distance of 249809.6 m |
|
| |
now, let's say that the spaceship stops accelerating or decelerating at this point because it is at the end of the detonation/deflagration cycle, and then the astronaut seat suddenly jerks forward to 2 g's because there is a damper on the recoil that only allows for this, then....astronaut goes from 2498.1 to 12490.5 (m/s) in a matter of 509.3 sec and hits the back at this very instance, while at the same time the ship has traversed another 6361411.7 m. |
|
| |
In conclusion, if you had a rocket ship that was 6373902.15 m long, and could perform so beautifully like this, then my bizzar and halfbaked scenario would work perfectly without the astronaut ever exceeding 10 g's while the ship clearly went as much as 50 g's at one instant. |
|
| |
ds= a dt^2 = a*t dt = 1/2 a t^2 {evaluated at S(t2)- S(t1)} |
|
| |
dv= a dt = a t {evaluated at V(t2)- V(t1)} |
|
| |
da= a {evaluated at A(t2)-A(t2)} |
|
| |
Yep, you're right. I've been passing too many days with no integration. |
|
| |
lol, this is halfbakery, that is why I didn't modify the calculations from what I originally halfbaked up in the main idea.... now it's time to get another bud light and read some more physics before I go to bed |
|
| |
What you've reinvented, quantum, is the shock absorber. These reduce peak accelerations, but the average accelerations are always the same. |
|
| |
//the spacesuit would have a narrow lunch window.// |
|
| |
Can I borrow that lunch window for my idea (see link)? |
|
| |
Pbbbbb, It's not just your average run of the mill shock absorber, this thing sends the astronaut flying from the front to the back of the spaceship, like a vertical or horizontal bungee jumping seat. After all, what type of shock absorber is known for doing this kind of thing, other than a "Low 'g' astro-slinky-seat"? You're not going to find anything else that quite compares because it's the strangeness factor that makes it unique from other shock absorbers, not the mathematics. |
|
| |
Case in point: These equations also could be interpreted as for launching a rocket with much cargo on it at high g's, and launching a human with a powerful jetpack at low g's and having them rendezvous and dock in space some 6373902.15 m out. |
|
| |
....Yeah, I suppose the average acceleration for the astronaut and the spaceship would both be about 22.74 m/s^2, or about 2.31 g's over the 549.3 seconds it would take to reach an equalibrium of position and velocity, good point (I've placed a revisional note in the idea to clear up this misunderstanding), but the important thing is that these peak accelerations wouldn't allow for the astronaut to be crushed upon launch. |
|
| |
//Why not have a rocket that provides sinusoidal g's, like a series of pulse detonations...// That's the part I'm still scratching my head over. There certainly isn't any type of "detonation" that I'm aware of which will ramp up and back down in a sine-wave form - much less over a period of 10 or 20 or 40 seconds. |
|
| |