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Judah14
Post subject: Re: SupergunsPosted: September 3rd, 2014, 9:01 am
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For orbital insertion, an upper rocket stage with guidance system is needed.


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ONI-Defense
Post subject: Re: SupergunsPosted: September 4th, 2014, 4:31 am
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It's in the mid-WIP stage currently. I decided to go with a tricore Tri/SWATH with three, nearly identical hulls.

I have already named it despite it being incomplete. The name I gave it is Baltimore Gun, in reference to the Baltimore Gun Club that built the space gun in Jules Verne's From the Earth to the Moon.

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Shipright
Post subject: Re: SupergunsPosted: September 8th, 2014, 6:16 pm
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There currently isn't a way to use a rail gun for orbital launch using a projectile without its own follow on propulsion. The starting speed you would need exiting the barrel to ensure it has enough energy throughout its flight to make it out of the atmosphere means you have to have maximum velocity at the greatest atmopshic pressue of the flight path. This means a starting velocity we can not currently achieve for useful payloads, friction forces no large projectile can survive using current materials tech, and even if it did survive is doubtful anything useful would survive meaning is basically dumb slugs.

And yes while putting the barrel muzzle at the top of the highest mountain does alleviate the atmospheric friction a bit its not enought to matter. I am not sure what the minimum velocity for a rail gun launch is which makes the projectile survivable while at the same time stable enough to host useful cargo or systems. If thats pretty high it might be useful as a the first stage of an orbital launch and then use a secondary rocket booster to get the rest of the way. Or it might not be worth it.


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apdsmith
Post subject: Re: SupergunsPosted: September 8th, 2014, 7:31 pm
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Hi Shipright,

Actually, there is no way to make a decent orbit without a secondary burn. Even if you have the world's biggest railgun, you'll either make escape velocity or you won't - and if you don't make escape your perigee is at sea level or lower (see "Lithobraking") if you're launching from a ship - the mountain idea is much better but even then it won't help much until your mountain reaches geostationary orbit. You need that secondary prograde burn around apogee to lift the perigee up.

That said, though, it'd be very useful for suborbital loads, though it's probably a bit too aggressive for delivering the newspapers...

(Why, yes, I am an orbiter addict, how did you guess?)

Regards,
Adam

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ONI-Defense
Post subject: Re: SupergunsPosted: September 9th, 2014, 12:54 am
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apdsmith wrote:
Actually, there is no way to make a decent orbit without a secondary burn.
That is something I factored into the concept. I completed the drawing yesterday but I've yet to post it because of second doubts about the practicality of the idea.

I can always convert the platform into a drilling ship or a crane vessel if I decide to drop the space launch concept.

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JSB
Post subject: Re: SupergunsPosted: September 9th, 2014, 7:02 am
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Would you not fix the 'gun' at the optimum lunch angle ? Why have it so it can move when it will only ever fire at the best angle for space flight and having it none moving will make it much easier (cheaper) to build and fit ?

Will it be a single barrel or will it have side combustion chambers along its length and do you not want it as long as possible to reduce acceleration ?

JSB


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Shipright
Post subject: Re: SupergunsPosted: September 9th, 2014, 11:57 am
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apdsmith wrote:
Hi Shipright,

Actually, there is no way to make a decent orbit without a secondary burn. Even if you have the world's biggest railgun, you'll either make escape velocity or you won't - and if you don't make escape your perigee is at sea level or lower (see "Lithobraking") if you're launching from a ship - the mountain idea is much better but even then it won't help much until your mountain reaches geostationary orbit. You need that secondary prograde burn around apogee to lift the perigee up.

That said, though, it'd be very useful for suborbital loads, though it's probably a bit too aggressive for delivering the newspapers...

(Why, yes, I am an orbiter addict, how did you guess?)

Regards,
Adam
Yeah that's another problem but I was thinking you could use it to deliver warheads worldwide or to resupply facilities already in orbit that will "catch" the payloads or some such.


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CraigH
Post subject: Re: SupergunsPosted: September 9th, 2014, 8:38 pm
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apdsmith wrote:
Hi Shipright,

Actually, there is no way to make a decent orbit without a secondary burn. Even if you have the world's biggest railgun, you'll either make escape velocity or you won't - and if you don't make escape your perigee is at sea level or lower (see "Lithobraking") if you're launching from a ship - the mountain idea is much better but even then it won't help much until your mountain reaches geostationary orbit. You need that secondary prograde burn around apogee to lift the perigee up.

That said, though, it'd be very useful for suborbital loads, though it's probably a bit too aggressive for delivering the newspapers...

(Why, yes, I am an orbiter addict, how did you guess?)

Regards,
Adam
Spotted you as an Orbinaut in a hearbeat! :lol:

Long Live the Probe,
CraigH

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heuhen
Post subject: Re: SupergunsPosted: September 9th, 2014, 9:49 pm
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I use postal-service....


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