Author Topic: Basic Rocket Science Q & A  (Read 281396 times)

Offline Avron

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Re: Basic Rocket Science Q & A
« Reply #960 on: 09/20/2014 09:16 PM »
Seems kinda like the opposite, the Saturn V and the old reliable Soyuz have happily launched in terrible weather, but these new launch vehicles don't.


so much for progress

Again, look up Apollo 12 for a weather lesson.

Sometimes things get pushed a little far.. still they all made it..

Is that what you tell your customer when his payload, for a change, *doesn't* make it?

Seriously...

seriously - progress is dismal  compared to all other forms of high speed transport..  in some cases it backwards.. Soyuz don't have that problem.. alas problems are elsewhere, it launches in some nasty  stuff 

Online ugordan

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Re: Basic Rocket Science Q & A
« Reply #961 on: 09/20/2014 09:22 PM »
seriously - progress is dismal  compared to all other forms of high speed transport.. 

When other forms of "high speed transport" have even a fraction of energy involved here, then we can talk apples-to-apples.
« Last Edit: 09/20/2014 09:22 PM by ugordan »

Offline Avron

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Re: Basic Rocket Science Q & A
« Reply #962 on: 09/20/2014 09:35 PM »
seriously - progress is dismal  compared to all other forms of high speed transport.. 

When other forms of "high speed transport" have even a fraction of energy involved here, then we can talk apples-to-apples.

  any aircraft in dense atmosphere, say 737 .. they fly is nasty stuff.. or A380 if the engine does not de-construct or a Soyuz, ICBM, f-119.. 

Online ugordan

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Re: Basic Rocket Science Q & A
« Reply #963 on: 09/20/2014 09:57 PM »
This is the kind of thing that happens when Apollo 12 lessons (more generally, reasons for specific LCCs) get "forgotten":


Sometimes "progress" is not launching when you want, but learning when NOT to launch.

Offline kevin-rf

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Re: Basic Rocket Science Q & A
« Reply #964 on: 09/26/2014 12:21 PM »
Also, don't forget AC-67. Lightning strikes have caused LOM's. No reason to risk it. 
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Offline GA

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Re: Basic Rocket Science Q & A
« Reply #965 on: 01/19/2015 04:03 PM »
Hi, does anyone know if (Tan x = 1) or (sin x/cos x = 1) means anything in astrophysics?

Offline kch

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Re: Basic Rocket Science Q & A
« Reply #966 on: 01/19/2015 04:24 PM »
Hi, does anyone know if (Tan x = 1) or (sin x/cos x = 1) means anything in astrophysics?

As far as I know, it means a 45 degree angle.  If there's something more to it than that, I'd be interested to hear about it!  :)

Online spacenut

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Re: Basic Rocket Science Q & A
« Reply #967 on: 03/30/2015 11:18 PM »
How fast would a spacecraft have to go to have 1 G acceleration?  If SEP acceleration can achieve 1 G, or even small chemical or nuclear rockets, is it possible to achieve 1 G acceleration to Mars, then 1 G deceleration getting there?  Also, if this is possible, how long would it take to get to Mars at continuous 1 G acceleration and deceleration?  Would it be easier to get 1/2 G? 

I was just wondering if this would be more practical than a spinning spacecraft on a slower trip.

Offline sandrot

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"Paper planes do fly much better than paper spacecrafts."

Online QuantumG

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Re: Basic Rocket Science Q & A
« Reply #969 on: 03/30/2015 11:28 PM »
I was just wondering if this would be more practical than a spinning spacecraft on a slower trip.

If by practical you mean magical, sure.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Online spacenut

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Re: Basic Rocket Science Q & A
« Reply #970 on: 03/31/2015 12:30 AM »
Ok, so we would have to have warp drive. 

Offline kevin-rf

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Re: Basic Rocket Science Q & A
« Reply #971 on: 03/31/2015 12:13 PM »
I'm cool with that. Get cracking ;)
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Offline baldusi

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Re: Basic Rocket Science Q & A
« Reply #972 on: 03/31/2015 03:04 PM »
I was just wondering if this would be more practical than a spinning spacecraft on a slower trip.

If by practical you mean magical, sure.
Well, if you could accelerate your exhaust speed to 0.034c, you'd have an isp of 1,000,000s. With that, assuming you can throttle down, you can get a 1g of acceleration during 3 days by using 25% of you craft mass. Thus, while completely unfeasible with known technology, it wouldn't look like it would violate any laws of physics. Fusion engine might enable that in a distant future.

Offline gbaikie

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Re: Basic Rocket Science Q & A
« Reply #973 on: 04/03/2015 02:57 AM »
How fast would a spacecraft have to go to have 1 G acceleration?  If SEP acceleration can achieve 1 G, or even small chemical or nuclear rockets, is it possible to achieve 1 G acceleration to Mars, then 1 G deceleration getting there?  Also, if this is possible, how long would it take to get to Mars at continuous 1 G acceleration and deceleration?  Would it be easier to get 1/2 G? 

I was just wondering if this would be more practical than a spinning spacecraft on a slower trip.

1 gee acceleration from Earth surface gets nowhere.
1 gee acceleration from LEO for about 10 minutes, is 5880 meters a second which will reach Mars in about 7 months. And 1 gee for about 20 minutes could reach Mars in less than 4 months. Say 15 mins at LEO and 5 mins at near Mars. Though there different ways of doing this.
And roughly 30 minute of 1 gee starting from LEO could reach Mars in about 3 months.

And from Earth elliptical orbit- say 300 by 200,000 km, with about 10 minutes at 1 gee one reach Mars in 3 to 4 months.

And it seems if got to Mars in about 3 months, one would need less shielding and receive less radiation and one would not need to make artificial gravity- one still have physiological affects from the microgravity
but they would be significantly less debilitating then compared to +6 months.

And to get 2 months- about 40 mins starting from LEO, and 20 mins starting from high orbit [highly elliptical orbit]. Though twice the acceleration for 1/2 the time would be more efficient. 

Online the_other_Doug

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Re: Basic Rocket Science Q & A
« Reply #974 on: 04/03/2015 06:09 PM »
And don't forget that one-G acceleration for five minutes got the Apollo CSM/LM stack from LEO to the Moon in three days...
-Doug  (With my shield, not yet upon it)

Online SkipMorrow

Re: Basic Rocket Science Q & A
« Reply #975 on: 05/05/2015 06:16 PM »
I am following the decay of Progress 27M, and people keep mentioning TLE and space-track.org. I went there and made an account for myself, but there isn't any help on the site as to how to read the data there.

[Edit: deleted quoted TLE info because of possible copyright issues]

If it is too hard to explain in a forum post, that's cool. But perhaps you can point me to a web page or book that I can read that explains it all?
« Last Edit: 05/05/2015 09:56 PM by SkipMorrow »

Online AnalogMan

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Offline satwatcher

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Re: Basic Rocket Science Q & A
« Reply #977 on: 05/05/2015 06:31 PM »
T.S. Kelso has a good FAQ on two-line elements: https://celestrak.com/columns/v04n03/

Also note that space-track.org typically does not allow you to share elements originating from their database (https://www.space-track.org/documentation#/user_agree). You may want to remove them and use elements from another source.

Offline kevin-rf

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Re: Basic Rocket Science Q & A
« Reply #978 on: 05/05/2015 06:40 PM »
Here is a quick and dirty spread sheet I use to calculate crude Apogee/Perigees from TLE's. It's based upon some posts people have made in the past. The numbers are crude and use a circular earth model (Shutter).
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Offline Apollo-phill

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Re: Basic Rocket Science Q & A
« Reply #979 on: 05/11/2015 04:19 PM »
What was the carrier aircraft for the X 37 test drops at EAFB circa 2005/6 ?

Image capturess from X 37 test flight B roll video