Traveller Store CotI Features New Posts Mark Forums Read Register


Go Back TravellerRPG.com > Citizens of the Imperium > Referee's Lounge

Referee's Lounge Discussion of how to (and not to) Referee Traveller and Cepheus Engine games. No edition warring allowed.

Reply
 
Thread Tools Display Modes
  #1  
Old October 27th, 2019, 01:41 PM
Tiikeri Tiikeri is offline
Citizen: SOC-12
 
Join Date: Jul 2013
Posts: 240
Gallery : 0
Tiikeri Citizen
Default How do i convert Traveller Gs to miles per hour?

The title says it all. How do i convert a traveller ship or grav vehicle's Gs to miles per hour?

If the ship or grav vehicle is on a 1g gravity world in a standard atmosphere, how do i compare how fast the ship is going with the sppeed of a jet or a rocket?

I found an acceleration converter online (1G is accelerating at about 21 mph per second) but i dont know how translate into mph cruising speed or max speed.

It would be great if someone can point out the relevant traveller book or other reference.
Reply With Quote
  #2  
Old October 27th, 2019, 03:39 PM
AnotherDilbert AnotherDilbert is offline
Citizen: SOC-14
 
Join Date: May 2008
Location: Stockholm 🇸🇪
Posts: 1,731
Gallery : 0
AnotherDilbert Citizen+AnotherDilbert Citizen+AnotherDilbert Citizen+
Default

Quote:
Originally Posted by Tiikeri View Post
How do i convert a traveller ship or grav vehicle's Gs to miles per hour?
The G rating is an acceleration or a thrust. In vaccum there will not be a maximum speed, but constant acceleration.

1 G ≈ 10 m/s2, so after 10 minutes (600 s) the ship will travel at 6000 m/s (21600 km/h ≈ 13500 mph).


Quote:
Originally Posted by Tiikeri View Post
If the ship or grav vehicle is on a 1g gravity world in a standard atmosphere, how do i compare how fast the ship is going with the sppeed of a jet or a rocket?
In an athmosphere the constant thrust will be resisted by drag (air resistance), and produce a top speed.

MT RM p86 suggests this:


Note that top speed is modified by streamlining and atmosphere density.

So, an Airframe (winged) ship with a 2 G drive in a Dense atmosphere would have a top speed of 2120 90% 75% = 1431 km/h ≈ 894 mph.
Reply With Quote
  #3  
Old October 27th, 2019, 04:28 PM
kilemall kilemall is online now
Citizen: SOC-14
 
Join Date: Apr 2015
Posts: 4,602
Gallery : 0
kilemall Respected Citizenkilemall Respected Citizenkilemall Respected Citizenkilemall Respected Citizenkilemall Respected Citizenkilemall Respected Citizen
Default

I've been working this but from a different angle, more reentry at a delta vee of 1+ by CT terms (which is 10,000 km every 1000 seconds, or 10 km/s).

For a kilometer per hour conversion, that's 3600 seconds for 36,000 km/h, converting to 22369 MPH. So ya, even the pokiest slow of speeds in space translates to unsustainable fast in planetary atmosphere.



What I want to quantify is at what point the ship starts taking damage, what point that damage progresses to destroyed, and short of that how much the ship will slow down possibly damaging the crew and cargo if not secured and of course 'uncontrolled impact'. The numbers are scary.


Fastest manmade object to make it down in one functional piece was the Stardust RV bringing back samples. 12.6 km/s on a deep drop cause no powered alteration/retro, hit 46Gs slowing down to subsonic in 110 seconds, then deployed chutes for the landing.


So atmosphere is a MAJOR drag, pardon the pun. That ship is going to act more at grav vehicle speeds if it's not breaking atmo OTW offplanet.
Course you could break atmo, retro to a low fast orbit and reenter like a powered ICBM RV, could get around the speed barrier that way.

Modern missiles are up to Mach 8 and design goals of Mach 15-20 last I checked, so we can presume most hyperspeed atmo vehicles of a higher tech can attain that with sufficient thrust.


https://en.wikipedia.org/wiki/3M22_Zircon
__________________
YUMV- Your Universe May Vary.
YOMD- Your Opinion May Differ.
Reply With Quote
  #4  
Old October 27th, 2019, 05:26 PM
Tiikeri Tiikeri is offline
Citizen: SOC-12
 
Join Date: Jul 2013
Posts: 240
Gallery : 0
Tiikeri Citizen
Default

Perfect, that's exactly the kind of information I was looking for. Thanks guys.
Reply With Quote
  #5  
Old October 28th, 2019, 01:28 AM
Grav_Moped Grav_Moped is offline
Citizen: SOC-12
 
Join Date: Oct 2016
Posts: 314
Gallery : 0
Grav_Moped Citizen
Default

Quote:
Originally Posted by kilemall View Post
...
Course you could break atmo, retro to a low fast orbit and reenter like a powered ICBM RV, could get around the speed barrier that way.

Modern missiles are up to Mach 8 and design goals of Mach 15-20 last I checked, so we can presume most hyperspeed atmo vehicles of a higher tech can attain that with sufficient thrust.
Not only retro to a low fast orbit, but also apply centripetal acceleration to achieve speeds well above orbital (escape) velocity. Apply reverse thrust at the end to drop velocity to something not totally insane before re-entry.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
12 Hour Classic Traveller Game: Lessons Learned & Future Tools Stan Shinn The Lone Star 4 August 8th, 2014 06:20 PM
Convert our solar system to a Traveller map jaz0nj4ckal The Lone Star 11 July 24th, 2012 05:55 PM
40 miles from nowhere Sackett Recruiting Office 3 March 24th, 2010 09:10 PM
Traveller T20 story hour cast of characters Shadowdancer Adventurers 2 January 4th, 2004 06:34 AM
Traveller T20 story hour Shadowdancer The Lone Star 0 November 10th, 2003 06:52 AM

This website and its contents are copyright ©2010- Far Future Enterprises. All rights reserved. Traveller is a registered trademark of Far Future Enterprises .
Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright (c) 2010-2013, Far Future Enterprises. All Rights Reserved.