10-19-2007
| #181 (permalink) | ||
 Slaying Bad Memes       | Re: Hypography X Prize Entry Quote:
But... (1) A restartable rocket engine is complex as hell. Trust me on this one. Getting a system reliability of 90% or more will be a real pain. A "light once and it burns until it's gone" rocket can be 99.99% reliable without too much cost. But... (2) The rocket you describe would require a much larger mass of fuel to do the same job as a burn-once rocket with high decelleration. Think of it this way: consider a rocket in a gravitational field, any strength, call it 1 "jee". If I fire the rocket against the grav field, then 1 jee of my acceleration is "wasted". 10 jees of "felt" accelleration actually gives me only 9 jees of "motion" accelleration; 3 jees of "felt" acc gives me 2 jees of "motion" acc; 1 jee of "felt" acc gives me 0 jees of "motion" acc -- as you would expect because now I am merely HOVERING. I am wastefully burning all my fuel just to fight gravity and not increasing my speed at all. Your "gradual firing just to keep the speed slow" rocket would be fuel inefficient for same or similar reasoning.  I am so sorry.---------------- Hypography Forums Moderator -- - - - - - What concerns me is not the way things are, but rather the way people think things are. Epictetus, Greek Philosopher The map is NOT the territory. Korzybski, Polish-American Philosopher | ||
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10-19-2007
| #182 (permalink) | |
 Explaining | Re: Hypography X Prize Entry Pyrotex: Hmm, that makes perfect sense, and is something I had not considered. So freefall to a calculated point and firing a one time rocket (or rockets?)would be the way to go for highest efficiency? It would still seem the calculations on when to fire the rockets should be fairly easy (for a rocket scientist :P ) to calculate, or am I wrong? ---------------- Thank goodness science is based on "survival of the fittest" rather than being a Democracy! Buffy Evolution is a hoot if you are one of the survivors. UncleAl | |
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10-19-2007
| #183 (permalink) | ||
 Resident Slayer  | Re: Hypography X Prize Entry A little warning before y'all go off the deep-end depending on us programmers to "automate everything": Quote:
There is always one more bug,  Buffy ---------------- "If you do not agree with anything I say, I'll not only retract it, but deny under oath that I ever said it!" __________________________________________________ ______________-- Tom Lehrer "The shrinks diagnosed me a sociopath with paranoid delusions. But they’re just out to get me cause I threatened to kill them." Forum Administrator Hypography Science Forums - Science for Boys and Girls! Its not for nothing that we hang out here. | ||
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10-19-2007
| #184 (permalink) | ||
 Doing the Impossible  | Re: Hypography X Prize Entry Quote:
Imagine we use the idea from Janus for a highly elliptical LEO, but it is so elliptical that we let the ship get caught by the gravity of the moon. Then as we fall to the moon all we need to do is hit as gently as possible. No orbiting the moon, just letting ourselves be drawn to the surface by gravity. We have an engine who's sole purpose is to remove all of our speed so end up "stopped" a fixed distance above the surface. At the moment that we are stopped we disconnect from that rocket and let it fly off into space consuming the rest of its fuel. At that point we use descent rockets to bring us to a landing. The trick is to get as close to the surface as possible with the slow down to minimize the fuel and hardware needed for the final descent and landing. The physics for this should be pretty straight forward. Is there a simulator we can play with, or can someone make a simulator for the launch to landing portion of the mission? Bill ---------------- aka TheBigDog - Hypography Full Freaking Moderator   Become a Hypography sponsor! The truth is incontravertible; malice may attack it, ignorance may deride it, but in the end there it is. - Winston Churchill TheBigDog's recommended reading: The Science of Success - Charles G. Koch A neutron goes into a bar and asks the bartender, "How much for a beer?" The bartender replies, "For you, no charge." | ||
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10-19-2007
| #185 (permalink) | |
 Married man  Sponsor | Re: Hypography X Prize Entry That sounds better TBD. While were on the subject of landing, I think it would be beneficial for everyone to take a look at this link. It is the 2006 Lunar Lander Challenge. The 2007 Challenge is coming up at the end of October. X PRIZE Foundation: Northrop Grumman Lunar Lander Challenge 2007 ---------------- Hypography Science Forums Moderator --- "There are no passengers on Spaceship Earth. We are all crew." - Marshall McLuhan "We must not forget that when radium was discovered no one knew that it would prove useful in hospitals. The work was one of pure science. And this is a proof that scientific work must not be considered from the point of view of the direct usefulness of it." - Marie Curie | |
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10-19-2007
| #186 (permalink) | |
| Doing the Impossible | Re: Hypography X Prize Entry Great link, freezy! It got me thinking about our own practical testing. I think that attaching a large helium balloon to simulate the lower gravity would be key. Controlling the flight that way under 1G instead of .17G is over-stressing the engineering really required for lunar performance. I am sticking with the Rover. I want desperately to play with large RC cars get to where I am controlling them via a web connection. Who knows, when I get it working I can rig it up so people can log in and control the test rover right here at Hypo. Bill ---------------- aka TheBigDog - Hypography Full Freaking Moderator Become a Hypography sponsor! The truth is incontravertible; malice may attack it, ignorance may deride it, but in the end there it is. - Winston Churchill TheBigDog's recommended reading: The Science of Success - Charles G. Koch A neutron goes into a bar and asks the bartender, "How much for a beer?" The bartender replies, "For you, no charge." | |
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10-19-2007
| #187 (permalink) | ||
 Dibbler  Sponsor |  Re: Hypography X Prize Entry Quote:
 Seems to me they are letting teams do all the work while they sit back & rake in the cash from the marketing. The $30 million prize is spit in a very large bucket. So screw them, and we instead build and finance the rover and launch as we planned, and do the raking in ourselves!  ----------------  Who doesn't want to use words that will stun people into silence? ~ShaYou gonna eat that? | ||
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10-19-2007
| #188 (permalink) | |||
| Married man Sponsor | Re: Hypography X Prize Entry Quote:
I liked the design of the lander that was launched in the 2006 competition. It looked very stable. The rockets were evenly spaced in a square pattern and the vehicle seemed to have a very low center of gravity. They seemed to have the worst luck with the "legs" of the lander, even with a "soft" landing. That's something we'll need to consider as well. Quote:
 ---------------- Hypography Science Forums Moderator --- "There are no passengers on Spaceship Earth. We are all crew." - Marshall McLuhan "We must not forget that when radium was discovered no one knew that it would prove useful in hospitals. The work was one of pure science. And this is a proof that scientific work must not be considered from the point of view of the direct usefulness of it." - Marie Curie | |||
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10-19-2007
| #189 (permalink) | |
| Doing the Impossible | Re: Hypography X Prize Entry I am getting my RC base this weekend. I went window shopping for RC's weekend before last. Spent some time asking lots of questions at Hobby Lobby. Most RC engines are built for high revs and speed. I want low rev engines that are for a marathon, not for a sprint. RC technology is all about sprinting, but there are other ways to skin that cat. I am trying to find the right platform. So far I am leaning toward this one... RadioShack.com - Toys & Games: Radio-controlled: Air, land & sea vehicles: Hummer® H2 with Mattracks Whadoyathink? Bill ---------------- aka TheBigDog - Hypography Full Freaking Moderator Become a Hypography sponsor! The truth is incontravertible; malice may attack it, ignorance may deride it, but in the end there it is. - Winston Churchill TheBigDog's recommended reading: The Science of Success - Charles G. Koch A neutron goes into a bar and asks the bartender, "How much for a beer?" The bartender replies, "For you, no charge." | |
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10-19-2007
| #190 (permalink) | ||
| Dibbler Sponsor |  Re: Hypography X Prize Entry Quote:
 Gotta start somewhere. Make sure when you're at RadioShack that you ask for a copy of their Master catalog. The first thing I would replace on your vehicle is the radio. The one supplied does not have continuous (not the right technical term) control of the servos, that is to say there is no partial throttle or turning. It's all or nothing. You need to control the camera too. Look for muti-channel RC systems; you can get up to 7 or 8 channels. Link below.  Went looking for a multichannel page and stumbled on some mini-gyros that interface with them. Do we need some of these? Gyro MS for HORNET - mscompositusa.comrobot parts >> SuperDroid Robots - DC Gearmotors, Gear Motors, Robot Motors super expensive whizz-bang radio >> JR PCM10X Air MD2 4-8611A & Case ---------------- Who doesn't want to use words that will stun people into silence? ~ShaYou gonna eat that? | ||
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