Sending A Rocket To The Moon! (Progress Sheet)

[stealth6]

I wonder if Orville and Wilbur got this kind of flack when they told someone they were going to invent the airplane.

I'm sure they endured MUCH worse.

BUT......they believed in what they were doing, continued forward despite the critics, and of course it didn't hurt that they had an idea that COULD actually work as it turned out.

s6

 

[shrox]

I'm sure they endured MUCH worse.

BUT......they believed in what they were doing, continued forward despite the critics, and of course it didn't hurt that they had an idea that COULD actually work as it turned out.

s6

Yes, I think we are just thought experimenting. The military probably isn't interested in a model moon rocket potential.

 

[beezwax]

I wonder if Orville and Wilbur got this kind of flack when they told someone they were going to invent the airplane.

They probably did, although that's also a bit apples-n-oranges I think. After all we have been to the moon, the project being discussed here is not inventing that technology. It's a hobbyist attempting to send a model rocket in the footsteps of the real deal. Now don't misunderstand my point, I am not saying that because it has been done already invalidates the idea. If you are a hobbyist and also happen to have millions of dollars at your disposal why not send a model rocket to the moon. But don't suggest that it is analogous to the Wright brothers inventing the airplane. A better analogy would be attempting to fly a model airplane from New York to Paris.

 

[beezwax]

So getting back on track, didn't some guy jump out of a balloon some 24 miles up? Can't that balloon be used again to get the 'model' rocket that high then launched from there. I know it's called a rockoon and it would be a 1/4 way there to LEO before launching. Somebody should have set that up when he pulled his stunt.

Yep that was Felix Baumgartner. The OP should contact Red Bull and see if they'll cut a good deal on a used balloon capsule, though that was also a multi-million dollar stunt. Time to set up the lemonade stand.

https://www.redbullstratos.com/

 

[sylvie369]

Whatever else happens in this thread, I'm thankful it's here because of George's post about the Kerbal Space Program. I'm completely addicted. I just made it into lunar orbit with enough fuel left to maneuver there for the first time, and managed to change to an orbit where I skimmed less than a thousand meters over the lunar surface. Wow. Didn't have a lander available, alas, and wasn't successful at getting back to Earth, but I think I'm getting the hang of it, and it's absolutely a blast. It'll dispel you of any "point towards the moon and light your motors" delusions you may have about flying to the moon. You've got to know some stuff to get there. Fortunately I read a lot of Arthur Clarke as a kid.

 

[jadebox]

[The Wright Brothers] believed in what they were doing, continued forward despite the critics, and of course it didn't hurt that they had an idea that COULD actually work as it turned out.

For the most part, they didn't tell anyone what they were doing. But, I think it was an attempt to protect their ideas rather than avoid criticism. Ironically, though, it caused problems for them later when others tried to take credit for the first controlled powered airplane flight and for the things they had invented.

-- Roger

 

[dlazarus6660]

I wonder if Orville and Wilbur got this kind of flack when they told someone they were going to invent the airplane.

While waiting at a large airport taxiway to takeoff, this came over the speaker. "Hey Orville, it's Wilbur, meet me in the bike shop, I got an idea!"

 

[GDJ]

How about launching a HPR with a 3-axis gyroscope for stability and launch it off the ISS in the same direction of the ISS path? Wouldn't the combined speed of the ISS orbital velocity plus the the HPR rockets's added velocity cause the path of the rocket to slowly spiral upwards as it goes around the Earth, eventually escaping orbit?

 

[BLKKROW]

How about launching a HPR with a 3-axis gyroscope for stability and launch it off the ISS in the same direction of the ISS path? Wouldn't the combined speed of the ISS orbital velocity plus the the HPR rockets's added velocity cause the path of the rocket to slowly spiral upwards as it goes around the Earth, eventually escaping orbit?

Please correct me if my Physics is wrong. But even if you launch the right in the same direction or trajectory of the ISS. It gets to a point where the burn ends and the rocket has reached maximum velocity, and has stopped accelerating also? So if it does not break orbit by that time, it will never make it to the moon.

Just a quick thought while I am at work, please correct me.

 

[Peartree]

Please correct me if my Physics is wrong. But even if you launch the right in the same direction or trajectory of the ISS. It gets to a point where the burn ends and the rocket has reached maximum velocity, and has stopped accelerating also? So if it does not break orbit by that time, it will never make it to the moon.

Just a quick thought while I am at work, please correct me.

As I understand it, if you don't reach escape velocity, you will have only reached the velocity needed for a higher orbit. Still in orbit. Now just higher up.

 

[jadebox]

How about launching a HPR with a 3-axis gyroscope for stability and launch it off the ISS in the same direction of the ISS path? Wouldn't the combined speed of the ISS orbital velocity plus the the HPR rockets's added velocity cause the path of the rocket to slowly spiral upwards as it goes around the Earth, eventually escaping orbit?

A rocket can't "spiral slowly upwards" without producing continuous thrust. Once the motor stops burning, the rocket will be in free-fall and will "fall back" into orbit around the earth if it hasn't reached escape velocity.

As has been mentioned a couple of times, the rocket would have to increase it's speed by a value called "delta-v" to leave earth orbit. Delta-v varies based on where the rocket is and where it's going - see the chart at:

https://en.wikipedia.org/wiki/Delta-v_budget#Earth.E2.80.93Moon_space_.E2.80.94_high_thrust

To leave low-earth orbit and reach the moon, requires an increase in speed of about 3 kilometers/second. As I showed previously, an ideal G motor can't accelerate it's own mass to that speed. Since the specific impulse of larger HPR motors is about the same, a non-clustered/staged high-power rocket wouldn't be able to do it.

And it would a really large clustered/staged HPR rocket to reach that speed.

I just played with the values I used for the "ideal" G motor - total impulse of 160Ns, thrust duration of 10 seconds, mass of 0.07 Kg. This ideal G motor could reach delta-v by staging from a cluster of two motors to a single motor.

But, when I change the mass of the motor to something more realistic, like the weight of a G138 reload in its case, the powers-of-two rocket can't be accelerated to more than about 1.7 kilometers/second no matter how many stages are added. A ten-stage rocket with 512 motors in the first stage reaches about 1.7 kilometers/second. A twenty-stage rocket with more than 500,000 motors in the first stage will reach a speed which is only about .05 kilometers/second faster.

A larger HPR motor, like an O motor, might be able to reach 3 kilometers/second using the scenario above because the ratio of the mass of the propellant to the total mass of the motor is larger. But it's trivializing the problem to answer it by saying that you could just use a bigger motor.

-- Roger

 

[shrox]

...But it's trivializing the problem to answer it by saying that you could just use a bigger motor...

Bigger motor always better and more glorious comrade.

 

[jadebox]

Bigger motor always better and more glorious comrade.

Yep ... you could even send a snowmobile to the moon if you attached a large enough motor ......

-- Roger

 

[RocKiteman]

​

Yep ... you could even send a snowmobile to the moon if you attached a large enough motor ......

There is snow on the moon...? :eyeroll:

:lol:

 

[gdiscenza]

There is snow on the moon...? :eyeroll:

:lol:

Not in the summertime! :rofl:

G.D.

 

[DaveHein]

I just played with the values I used for the "ideal" G motor - total impulse of 160Ns, thrust duration of 10 seconds, mass of 0.07 Kg. This ideal G motor could reach delta-v by staging from a cluster of two motors to a single motor.

But, when I change the mass of the motor to something more realistic, like the weight of a G138 reload in its case, the powers-of-two rocket can't be accelerated to more than about 1.7 kilometers/second no matter how many stages are added. A ten-stage rocket with 512 motors in the first stage reaches about 1.7 kilometers/second. A twenty-stage rocket with more than 500,000 motors in the first stage will reach a speed which is only about .05 kilometers/second faster.

Are you sure you did the calculations correctly. You should be able to easily acheive a delta-v of 5 km/s with a 10 stage rocket -- even with the low propellant mass ratio of hobby rocket motors. What did you use for the mass ratio and Isp in your calculations?

 

[jadebox]

Are you sure you did the calculations correctly. You should be able to easily acheive a delta-v of 5 km/s with a 10 stage rocket -- even with the low propellant mass ratio of hobby rocket motors. What did you use for the mass ratio and Isp in your calculations?

I used a motor with 160Ns of total impulse (16N x 10s) and a mass of 0.15 kg.

You were quoting the description of a rocket with each lower stage having twice the motors of the previous stage. With the mass of each stage doubling, it reached a limit pretty quickly.

But, I just went back and looked at the 10-stage version of the rocket with just one motor in each stage. It does reach 3000 m/s after nine stages. It takes about 50 stages to reach 5000 m/s.

I used a simple model starting with F=ma.

F = ma
a = F / m
v = a * t
v = F / m * t

Stage10: v10 = 16N / .15kg * 10s = 1066 m/s
Stage9: v9 = 16N / .30kg * 10s = 533 m/s
...
Stage1: v1 = 16N / 1.5kg * 10s = 107 m/s

v10 + v9 ... + v1 = 3100 m/s

-- Roger

 

[shrox]

I used a motor with 160Ns of total impulse (16N x 10s) and a mass of 0.15 kg.

You were quoting the description of a rocket with each lower stage having twice the motors of the previous stage. With the mass of each stage doubling, it reached a limit pretty quickly.

But, I just went back and looked at the 10-stage version of the rocket with just one motor in each stage. It does reach 3000 m/s after nine stages. It takes about 50 stages to reach 5000 m/s.

I used a simple model starting with F=ma.

F = ma
a = F / m
v = a * t
v = F / m * t

Stage10: v10 = 16N / .15kg * 10s = 1066 m/s
Stage9: v9 = 16N / .30kg * 10s = 533 m/s
...
Stage1: v1 = 16N / 1.5kg * 10s = 107 m/s

v10 + v9 ... + v1 = 3100 m/s

-- Roger

What about the space fins and space parachute?

 

[DaveHein]

A rocket built out of equal stages will require more stages than one with unequal stages. Also, if you use the rocket equation you will get a higher delta-v because it factors in the reduction in mass as the propellant is burned.

A G138 rocket motor has 70 grams of propellant, and a initial mass of 148 grams, so it has a propellant mass ratio of 0.473. It's impulse is 157.1 Ns, which works out to an Isp of 229. A single G138 will produce a delta-v of 1438 m/s. If we build a 10-stage rocket, where each stage is a single G138 we will get a delta-v of 3.6 km/s. If each stage is twice as large as the previous, a 10-stage rocket will produce a delta-v of 7.3 km/s.

A 4-stage rocket that contains stages of 1, 8, 64 and 512 G138s will produce a delta-v of 5.1 km/s

EDIT: I believe space fins and a space parachute have zero mass.

 

[shrox]

...EDIT: I believe space fins and a space parachute have zero mass.

Excellent. I was greatly concerned.

 

[RodRocket]

I think the mechanical part of getting an amateur rocket to the moon can be accomplished with todays technology. We already have rockets reaching over 100,000 feet.

Getting the rocket to the moon isn't going to be the hard part. The hard part is proving it made it. Electronics will have to be the biggest part of the payload to transmit the data back to earth.

The original idea as I understood it was to get the rocket from earth to the moon. No mention of orbits, or a controlled landing.

It is basically a giant rocket launch to see if it will hit the moon. A giant target shoot.

With the long burn engines we currently have, I think it is totally possible. Do I want to try it. Not really. But that shouldn't deter someone who does.

Like I said getting there will be easier than proving it.

 

[jadebox]

A rocket built out of equal stages will require more stages than one with unequal stages. Also, if you use the rocket equation you will get a higher delta-v because it factors in the reduction in mass as the propellant is burned.

A G138 rocket motor has 70 grams of propellant, and a initial mass of 148 grams, so it has a propellant mass ratio of 0.473. It's impulse is 157.1 Ns, which works out to an Isp of 229. A single G138 will produce a delta-v of 1438 m/s. If we build a 10-stage rocket, where each stage is a single G138 we will get a delta-v of 3.6 km/s.

That's not much different than my results. I realized that I was not accounting for the decrease in mass of the propellant during the burn, but I also didn't add any mass to account for other parts that would be needed for rocket.

If each stage is twice as large as the previous, a 10-stage rocket will produce a delta-v of 7.3 km/s.

I forgot to multiply the thrust by the number of motors in each stage. So, each of my stages was powered by just one motor.

Now, I get a delta-v of about 6000 m/s/s after 10 stages using my simple model. That's more in line with your results.

-- Roger

 

[Zeus-cat]

For the most part, they didn't tell anyone what they were doing. But, I think it was an attempt to protect their ideas rather than avoid criticism. Ironically, though, it caused problems for them later when others tried to take credit for the first controlled powered airplane flight and for the things they had invented.

-- Roger

Living near Dayton I have heard many times that the Wright Brothers were very protective of their ideas. However, they consulted with many of the top aeronautical experts of the day and shared information with them. They shunned publicity as they did not want the press and the general public to be poking around. First and foremost they were businessmen who wanted to develop a product and sell it; they were not a couple of guys who just tinkered around with the idea of flying.

 

[jadebox]

Living near Dayton I have heard many times that the Wright Brothers were very protective of their ideas. However, they consulted with many of the top aeronautical experts of the day and shared information with them. They shunned publicity as they did not want the press and the general public to be poking around. First and foremost they were businessmen who wanted to develop a product and sell it; they were not a couple of guys who just tinkered around with the idea of flying.

That's true. I admire them for taking a deliberate scientific and engineering approach. Many others at the time were taking "all or nothing" types of attempts at making powered aircraft work. Many of them were more like daredevil stuntmen than inventors.

I read a couple of really good bios of the Wright Brothers a few years ago (one was To Conquer the Air, I don't recall the name of the other). The story makes a good book because of the multiple challenges the brothers faced - technical, financial, and legal. After years of shunning publicy, they found themselves in a situation where they needed to make a public splash. And they figured out how to do it in a big way.

A bit of trivia I found interesting is that Orville lived long enough to see supersonic aircraft and to fly in an airplane with a wingspan longer than the distance he had flown on his first flight.

-- Roger

 

[mbauer]

The fact that we have been to the moon 6 times, brought back a couple of hundred pounds of moon rocks and found nothing else.

You'd be wrong about the "Found Nothing else". Helium3 is in great abundance, the moon can be used as a source for Rocket Fuel! Staging/launching rockets to the outer planets.

Mike

 

[mbauer]

The OP is in some very awesome company when it comes to ridicule; about his dream. Robert Goddard was made fun of by several newspapers, they laughed at a few of his articles on rocket flight. Made him more secretive. Didn't stop him from doing his research though.

Anybody here read about some of the first flights to send objects to the moon?

Might want to do some reading... Peter Alway's book, Rockets of the World is a great start!

Mike

 

[beezwax]

The OP is in some very awesome company when it comes to ridicule; about his dream. Robert Goddard was made fun of by several newspapers, they laughed at a few of his articles on rocket flight. Made him more secretive. Didn't stop him from doing his research though.

Anybody here read about some of the first flights to send objects to the moon?

Might want to do some reading... Peter Alway's book, Rockets of the World is a great start!

Mike

Sure. And if I stop combing my hair, walk around without socks and get mediocre marks in school that puts me in great company with Einstein. But it doesn't make me a genius. Be careful of false syllogisms.

 

[bobkrech]

You'd be wrong about the "Found Nothing else". Helium3 is in great abundance, the moon can be used as a source for Rocket Fuel! Staging/launching rockets to the outer planets.

Mike

Mike

I don't want to curb your enthusiasm, but 1-50 ppb is not abundant. Helium-3 is far more abundant (but still exceeding rare), and more readily obtainable, from terrestrial sources such as natural gas wells.

Since the beginning of the atomic age hundreds of billions of dollars have been expended worldwide in attempts to produce a break-even fusion reactor without success, and the development of a successful and practical fusion reactor is a prerequisite for any fusion drive propulsion system IMO. While a fusion drive propulsion system might be theoretically possible, there is no economic or strategic justification for one so it is unlikely to occur for centuries to come.

Bob