RCM Challenge

I think you have a great idea. There are a lot of very talented people who read this newsgroup, each with varying resources and tooling. Perhaps this fellow Robert Richards would wish to place item drawings on a web site for hobbiests to make. Sort of like an outsourcing thing to defray his expenses. I think organizing and managing this would be a significant challenge, but I think it could be done. Consider the value and power a worldwide fabrication and problem solving facility and at your fingertips. This has to be attractive. Steve

I think it a "roll yer own" type thing.

Steve Lusardi wrote:

in my local environment it is only I who thinks this a damn interesting challenge.

I've nutted out some of the technicalities just in the idle moments today.

navigation to the moon is a piece of cake. launch just before midnight on a moonlit night and have the robot navigator stay focussed on the large polarised dot of light in the sky and head for it.

gods I'd get a legit excuse to experiment with godard rockets!

payload could be the size of a radio controlled model car. launch a whole bundle of them for redundancy.

how do you prove you got there? find and cut down the american flag and replace it with an australian one :-) that'd be sure to see a moon mission just to put back a bigger american one :-)

damn what an interesting challenge!

Stealth Pilot

Won't work; you cannot go directly to the moon, you have to go around the earth because of gravity and the earth's rotation. In any case, it will take several days to get there ;)

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

can you tell me why a vehicle making a steady 100knots cant get to the moon? oil tankers traverse the world at 12 knots.

ok the full plot is ...launch on a moon lit night. get a stable ascent, lock in the inputs from the stabilising gyros as setpoints. proceed in a straight line. when the clock indicates that the moon is almost in position each day scan the forward sky for the moon. compute the course correction, adjust, lock in the gyro inputs as setpoints. proceed in a straight line. uniform motion in a straight line requires no thrust. you merely need thrust to adjust for gravity. toward the moon adjust course to chase the trajectory with a view to getting almost to lunar speed. since the moon isnt spinning it shouldnt be too hard to arrange an intercept sorta like driving in a parallel lane to another car on the freeway.

actually, rather than having a smart arsed tilt at you I'd appreciate some comments on what would be actually be needed.

Stealth Pilot free men live in societies where guns arent needed.

That's a good question and one worth the time it takes to understand it. Look up "escape velocity" and you'll see the equations.

The short answer is that you couldn't carry enough fuel to escape gravity that way. A projectile under power must achieve some very high percentage of the Earth's escape velocity, which is roughly 11.2 km/sec. Otherwise your fuel supply will never last. Once you've achieved escape velocity, that's the velocity you should try to conserve on your trip to the Moon.

-- Ed Huntress

The oil tanker doesn't need an engine powerful enough to lift itself. For each extra mile you climb you need the fuel to rise that mile plus the added fuel to raise that fuel plus the fuel to raise the added fuel ...

It's like building a mountain out of marbles.

IIRC escape velocity from earth orbit is about 24,ooo mph (minimum)

100 kts won't even stay in orbit. That's up around 18,000.

While it may not make sense, launching straight up will not put you into orbit. Nor is it a workable way to get to to moon.

The trick here is to aim for a point about 50 miles in front of where the moon will be - when you get there. Which is all done with computers!

Just like Apollo did, boost into earth orbit, TLI (Trans Lunar Injection) takes you out towards the moon, course corrections as required, then a braking burn to lunar orbit.

THEN you still have to get down, but without squishy people aboard that might be easier that it was back then. A big burn to drop the speed and a multi-balloon air bag to absorb the landing impact.

I'd kiss each of their pointy little heads, if only they would...

Sure: 100 knots is nowhere near escape velocity from the earth.

Also, the moon is a quarter of a million miles away. At a hundred knots, it would take you three and a half months to get there. That's an awful lot of food to have to bring along...

You can circumnavigate the globe at 12 knots in less time than it would take to fly to the moon at 100 knots. And there's a lot more space for food and supplies on an oil tanker than there is on a spacecraft.

Proceed in a straight line... and miss the moon by two hundred million miles. (That's a rough approximation of how far the earth-moon system would move in orbit around the sun in 3.5 months.)

Correct -- but what you describe is not a straight line.

Incorrect. You need continuous lateral thrust to adjust for the moon's motion in its orbit around the earth, and the motion of the pair in their orbit around the sun. If you want to keep the moon in front of you, you're going to be flying in an expanding-spiral trajectory.

Actually, it does rotate on its axis. But whether it does or not is of no relevance.

The biggest issue, aside from the need to achieve escape velocity, is the enormous amount of fuel that would be required for continuous course corrections to maintain the aforementioned spiral trajectory. It's

*much* more efficient to compute where the moon is going to be when you get there, and fly in a straight line to that point.

Have you ever watched little children playing soccer? Up until about age seven, they run after the ball, just like a horde of puppies, following it wherever it goes. Somewhere around age eight or nine, they begin to anticipate the ball's path, and start to run to the spot where the ball will be when they get there.

Which way do you think works better? :-)

Free men live in societies where they have anything they can buy or make ;)

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

Those without weapons, will plow for those that do.

Gunner

No. You couldn't possibly carry enough fuel for the continuous course changes needed to maintain that hyperbolic trajectory. You need to figure out how long it's going to take to get there, and where the moon will be at that time. Then aim at that point.

On Tue, 11 Dec 2007 14:30:50 GMT, with neither quill nor qualm, T. Rex quickly quoth:

I just need to perfect my gravimetric drive.

-- My future starts when I wake up every morning... Every day I find something creative to do with my life. -- Miles Davis

(...)

Forget the electromagnets and 'D' cells Larry.

:)

--Winston

While you are finishing u p on that :)

Lets start with a 100 pound payload. several rovers for redundency and a "soft landing" package.

On Tue, 11 Dec 2007 17:14:07 GMT, with neither quill nor qualm, Winston quickly quoth:

_D_ cells? OK, I'll scrap my AAAA cell theory now. I'm back on the cold-fusion buttons once again.

-- My future starts when I wake up every morning... Every day I find something creative to do with my life. -- Miles Davis

In article balloon, and the then firing the rocket in earth orbit?

Yes, that is done but you only save a small amount unless you take the balloon VERY high. Usually the rocket us launched THROUGH the balloon and destroys it ;)

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/