# Another railgun question

**URL:** <https://boards.straightdope.com/t/another-railgun-question/127856>\
**Category:** Factual Questions\
**Created:** [September 10, 2002, 10:10pm UTC](https://boards.straightdope.com/t/another-railgun-question/127856 "2002-09-10T22:10:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\
**Post date:** [September 10, 2002, 10:10pm UTC](https://boards.straightdope.com/t/another-railgun-question/127856/1 "2002-09-10T22:10:36Z")

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Is it possible to use a railgun to launch a payload into a stable orbit using other gravity wells such as the moon and sun (and a heck of a good timing)?

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**Author:** ![wolfman](https://avatars.discourse-cdn.com/v4/letter/w/a8b319/32.png) [@wolfman](https://boards.straightdope.com/u/wolfman)\
**Post date:** [September 10, 2002, 10:30pm UTC](https://boards.straightdope.com/t/another-railgun-question/127856/2 "2002-09-10T22:30:03Z")

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Some scientists think It’s possible. One of the big problems Is figuring out a useful payload that can handle that much acceleration,  
Here’s a link that talks about some of it, and in my quick skim it looked scientificish  
[http://www.fas.org/news/iraq/1998/05/980500-bull.htm](http://www.fas.org/news/iraq/1998/05/980500-bull.htm)

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**Author:** ![UncleAl0](https://avatars.discourse-cdn.com/v4/letter/u/a9a28c/32.png) [@UncleAl0](https://boards.straightdope.com/u/UncleAl0)\
**Post date:** [September 10, 2002, 10:33pm UTC](https://boards.straightdope.com/t/another-railgun-question/127856/3 "2002-09-10T22:33:46Z")

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First you must bore through 50 miles of atmosphere with all the velocity imparted at the bottom,plus friciton loses. Bummer for the payload. Naval guns have been used to go suborbital. The paylaods are potted solid.

Railguns are notoriously energy inefficient. Getting 5 miles/second (Mach 25) net at the top of the trajectory is not going to happen. Military railgun sabot projectiles top off around 1.5 miles/second. Orbital insertion with a single impulse doesn’t work. You would need at least one course correction to round the orbit.

The moon’s gravity won’t affect anything at launch.

If you want to get humanity off this rock you need different physics, not more engineering. That means you must find a flaw in a physics founding postulate and create a more inclusive science. Good luck.

–  
Uncle Al  
[http://www.mazepath.com/uncleal/eotvos.htm](http://www.mazepath.com/uncleal/eotvos.htm)  
(Do something naughty to physics)