Traveller Store CotI Features New Posts Mark Forums Read Register


Go Back TravellerRPG.com > Citizens of the Imperium > General Traveller Discussions > Imperial Research Station

Imperial Research Station A forum for discussing technology and related topics for use in the Traveller Universe

Reply
 
Thread Tools Display Modes
  #1  
Old August 10th, 2012, 01:27 AM
Carlobrand Carlobrand is offline
Citizen: SOC-14
 
Join Date: Feb 2012
Posts: 3,604
Gallery : 1
Visit Carlobrand's Blog
Carlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected Citizen
Default COACC rocket vs. Hard Times rocket

COACC rocket vs. Hard Times rocket: which is more "realistic"?

COACC offers a rocket for use as an engine in flying craft to permit craft to fly in space, among other things. Hard Times, of course, offers rocket engines too.

As near as I can tell, all other things being equal the Hard Times rockets burn 25 to 30 times as much fuel to achieve the same amount of thrust, they're twice as big (but roughly similar in weight), and they cost a lot less. I understand Hard Times engines were drawn pretty closely from real life - to the extent that real life examples existed.

Different rule sets, of course, but inquiring minds go where they will.
Reply With Quote
  #2  
Old August 10th, 2012, 08:00 AM
atpollard's Avatar
atpollard atpollard is offline
Citizen: SOC-14
 
Join Date: Oct 2006
Location: Port Richey
Posts: 9,414
Gallery : 43
Visit atpollard's Blog
atpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesome
Default

IMHO Hard Times will work better in a hard-science (like 2300AD) setting since it is closer to 'reality'.

On the other hand, the COACC rocket will fit better in a 'Classic Traveller' campaign since the performance is more in agreement with the other Traveller magic technologies like Maneuver Drive/Anti-Gravity (no Conservation of Momentum) and cold fusion Power Plants (no giant radiators).

[This is not a rant against Traveller Tech, just an acknowledgment that it differs from hard science in some areas.]
Reply With Quote
  #3  
Old August 11th, 2012, 09:39 PM
Carlobrand Carlobrand is offline
Citizen: SOC-14
 
Join Date: Feb 2012
Posts: 3,604
Gallery : 1
Visit Carlobrand's Blog
Carlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected Citizen
Default

Thing is, I could embrace this as "magic tech" if it weren't for the tech level. One does not expect "magic tech" in the past.

Let's look at this:

Your basic Saturn-V F1 engine delivers ~6.67 million Newtons, burning roughly 430 metric tons (430,000 liters) of fuel in 168 seconds. So, about 2560 liters per second, with each liter delivering ~2600 Newtons. It weighed a bit under 8 and a half metric tons.

A space shuttle main engine (RS-25) is more efficient, delivering about 4500 newtons per liter burned (in vacuum; about 3600 in atmosphere). It weighs about 3 1/2 metric tons.

Your Hard Times TL6 liquid rocket delivers 40 tons of thrust, burning 605 thousand liters per hour, and weighs a ton. 40 tons of thrust in Traveller means enough thrust to push 40 tons at 1g, so 400,000 Newtons? 605,000 liters per hour is 168 liters per second, so each liter delivers 2380 Newtons, not quite the efficiency of the F1, but reasonably close - though it weighs twice as much for the same performance. The TL7 delivers 45 tons with 570 kl/h, better than 2800 Newtons per liter. There's nothing quite matching the Space Shuttle engine, more's the pity.

Your COACC TL6 basic rocket delivers 30 tons of thrust, burning 19200 liters per hour, and weighs a ton. 30 tons of thrust in Traveller means enough thrust to push 30 tons at 1g, so 300,000 Newtons? 19200 liters per hour is 5.33 liters per second, so each liter delivers better than 56,000 Newtons - which translates to better than 20 times the specific impulse of the F1. The HP rocket delivers more thrust per engine weight, but consumes more fuel. Neither delivers as much thrust per ton of engine as the F1, but their fuel efficiency compares with some ion engines (and they are very clearly not ion engines).

So, out of curiosity - just how accurate are the other COACC engines?
Reply With Quote
  #4  
Old August 12th, 2012, 03:30 AM
aramis's Avatar
aramis aramis is offline
Administrator
 
Join Date: May 2001
Location: Anchorage, AK, USofA
Posts: 29,408
Gallery : 56
Visit aramis's Blog
aramis has disabled reputation
Send a message via ICQ to aramis Send a message via AIM to aramis Send a message via Yahoo to aramis
Default

yes, 1 Ton of thrust is 10kN.

The COACC rocket has an issue - the fuel masses 1 ton per 1000L - which means it's not LHyd and O2.

The energy release is excessive in COACC plants - best to ignore them in favor of HT.
__________________
~ Aramis
aramis.hostman.us /trav
Smith & Wesson: The Original Point and Click interface!

Archduke of Sylea (CORE 2118)
Duke of the Third Imperium (SPIN 0534)
Count Terra (SOLO 1827)
Count Gorod (REFT 1302)
Count of the Third Imperium (SPIN 2232)
Viscount of Adabicci (SPIN 1824)
Marquis of the Solomani Rim (SOLO 0606)
Marquis of the Third Imperium (SPIN 2410)
Baron of the Third Imperium (SPIN 2231)
Knight of the Iridium Throne (CORE 1434)
Sir William Hostman (OLDE 0512)
Sir William Hostman (DAGU 0622)
Knight of Deneb (REFT 2239)
Knight of Deneb (Spin 2532)
SEH w/Diamonds for Extreme Heroism - Battle of Boughene
MCG - Battle of Boughene
TAS: William Hostman (CORR 2506)
TAS: Bearer (DAIB 1326)
IMTU ct+ tm++ tne tg-- tt+ tmo+ t4- t20+ to ru+ ge+ 3i+ c+ jt au ls pi+ ta he+ st+
Wil Hostman 0602 C539857-9 S A724
OTU: 95% 3i an+ au+ br- cpu± dt± f+ fs++ ge± ih- inf± j± jf+ jm+ jt+ ls- n= nc+ pi+ pp-- tp+ tr+ tv- vi-- xb+-
Unless there is bold red text, presume my posts to be my personal material only.
Reply With Quote
  #5  
Old August 12th, 2012, 08:17 AM
atpollard's Avatar
atpollard atpollard is offline
Citizen: SOC-14
 
Join Date: Oct 2006
Location: Port Richey
Posts: 9,414
Gallery : 43
Visit atpollard's Blog
atpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesome
Default

Quote:
Originally Posted by aramis View Post
The energy release is excessive in COACC plants - best to ignore them in favor of HT.
Just a question for clarity, but isn't the standard Fusion Power Plant /Maneuver Drive just as bad?

(I have vauge recolections of the rocket equation yielding the equivalent of FTL exhaust for all traveller drives.)
Reply With Quote
  #6  
Old August 12th, 2012, 02:38 PM
mike wightman's Avatar
mike wightman mike wightman is offline
Noble
 
Join Date: Jun 2003
Location: Newcastle
Posts: 16,605
Gallery : 0
mike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizenmike wightman Respected Citizen
Default

The standard fusion plant/maneuver drive is Traveller magitec, the rockets are supposed to be real world science.
__________________
The beauty of CT LBB1-3 is that the ref is free to make such decisions for themselves.
Reply With Quote
  #7  
Old August 12th, 2012, 02:57 PM
Dragoner Dragoner is offline
Citizen: SOC-14
 
Join Date: Oct 2009
Posts: 3,049
Gallery : 0
Dragoner Citizen-
Default

Quote:
Originally Posted by Carlobrand View Post
Thing is, I could embrace this as "magic tech" if it weren't for the tech level. One does not expect "magic tech" in the past.

Let's look at this:

Your basic Saturn-V F1 engine delivers ~6.67 million Newtons, burning roughly 430 metric tons (430,000 liters) of fuel in 168 seconds. So, about 2560 liters per second, with each liter delivering ~2600 Newtons. It weighed a bit under 8 and a half metric tons.

A space shuttle main engine (RS-25) is more efficient, delivering about 4500 newtons per liter burned (in vacuum; about 3600 in atmosphere). It weighs about 3 1/2 metric tons.

Your Hard Times TL6 liquid rocket delivers 40 tons of thrust, burning 605 thousand liters per hour, and weighs a ton. 40 tons of thrust in Traveller means enough thrust to push 40 tons at 1g, so 400,000 Newtons? 605,000 liters per hour is 168 liters per second, so each liter delivers 2380 Newtons, not quite the efficiency of the F1, but reasonably close - though it weighs twice as much for the same performance. The TL7 delivers 45 tons with 570 kl/h, better than 2800 Newtons per liter. There's nothing quite matching the Space Shuttle engine, more's the pity.

Your COACC TL6 basic rocket delivers 30 tons of thrust, burning 19200 liters per hour, and weighs a ton. 30 tons of thrust in Traveller means enough thrust to push 30 tons at 1g, so 300,000 Newtons? 19200 liters per hour is 5.33 liters per second, so each liter delivers better than 56,000 Newtons - which translates to better than 20 times the specific impulse of the F1. The HP rocket delivers more thrust per engine weight, but consumes more fuel. Neither delivers as much thrust per ton of engine as the F1, but their fuel efficiency compares with some ion engines (and they are very clearly not ion engines).

So, out of curiosity - just how accurate are the other COACC engines?
IMO, after having done the calc's (nice BTW), I would use the real world values.

To give the rules writers some credit, much was written pre-internet so their sources were limited.
Reply With Quote
  #8  
Old August 12th, 2012, 08:39 PM
atpollard's Avatar
atpollard atpollard is offline
Citizen: SOC-14
 
Join Date: Oct 2006
Location: Port Richey
Posts: 9,414
Gallery : 43
Visit atpollard's Blog
atpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesomeatpollard Awesome
Default

I think that Hard Times aimed for realism (and did a good job of achieving it).
I think COACC attempted to aim for better compatibility with the rest of the magitech.
Reply With Quote
  #9  
Old August 13th, 2012, 01:26 AM
aramis's Avatar
aramis aramis is offline
Administrator
 
Join Date: May 2001
Location: Anchorage, AK, USofA
Posts: 29,408
Gallery : 56
Visit aramis's Blog
aramis has disabled reputation
Send a message via ICQ to aramis Send a message via AIM to aramis Send a message via Yahoo to aramis
Default

Quote:
Originally Posted by atpollard View Post
Just a question for clarity, but isn't the standard Fusion Power Plant /Maneuver Drive just as bad?

(I have vauge recolections of the rocket equation yielding the equivalent of FTL exhaust for all traveller drives.)
That's TNE's HEPlaR. Which is near-C exhaust - it's throwing bay-weapon-level amounts of energy, and should be generating major radiation hits on the starport upon landing and takeoff...

The Maneuver Drive in MT is gravitic tech, not a particle thrower. It has effectively infinite ISP... as long as it gets power. In the inner system, it's possible to get a ship going quite impressively fast, even with T4's 1000 diameter limit on gravitic M-Drives.
__________________
~ Aramis
aramis.hostman.us /trav
Smith & Wesson: The Original Point and Click interface!

Archduke of Sylea (CORE 2118)
Duke of the Third Imperium (SPIN 0534)
Count Terra (SOLO 1827)
Count Gorod (REFT 1302)
Count of the Third Imperium (SPIN 2232)
Viscount of Adabicci (SPIN 1824)
Marquis of the Solomani Rim (SOLO 0606)
Marquis of the Third Imperium (SPIN 2410)
Baron of the Third Imperium (SPIN 2231)
Knight of the Iridium Throne (CORE 1434)
Sir William Hostman (OLDE 0512)
Sir William Hostman (DAGU 0622)
Knight of Deneb (REFT 2239)
Knight of Deneb (Spin 2532)
SEH w/Diamonds for Extreme Heroism - Battle of Boughene
MCG - Battle of Boughene
TAS: William Hostman (CORR 2506)
TAS: Bearer (DAIB 1326)
IMTU ct+ tm++ tne tg-- tt+ tmo+ t4- t20+ to ru+ ge+ 3i+ c+ jt au ls pi+ ta he+ st+
Wil Hostman 0602 C539857-9 S A724
OTU: 95% 3i an+ au+ br- cpu± dt± f+ fs++ ge± ih- inf± j± jf+ jm+ jt+ ls- n= nc+ pi+ pp-- tp+ tr+ tv- vi-- xb+-
Unless there is bold red text, presume my posts to be my personal material only.
Reply With Quote
  #10  
Old August 13th, 2012, 10:12 PM
Carlobrand Carlobrand is offline
Citizen: SOC-14
 
Join Date: Feb 2012
Posts: 3,604
Gallery : 1
Visit Carlobrand's Blog
Carlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected CitizenCarlobrand Respected Citizen
Default

Quote:
Originally Posted by aramis View Post
That's TNE's HEPlaR. Which is near-C exhaust - it's throwing bay-weapon-level amounts of energy, and should be generating major radiation hits on the starport upon landing and takeoff...

The Maneuver Drive in MT is gravitic tech, not a particle thrower. It has effectively infinite ISP... as long as it gets power. In the inner system, it's possible to get a ship going quite impressively fast, even with T4's 1000 diameter limit on gravitic M-Drives.
Suppose. when in atmosphere, you superheated atmosphere as the working fluid? Wouldn't need magically fantastic exhaust velocities.
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
A rocket tour Gray Pennell Imperial Research Station 0 June 27th, 2012 03:26 PM
Scatterletto TL12 Shotgun HEAP rocket samuelvss Ship's Locker 9 September 21st, 2011 12:26 PM
Ares rocket test successful. BlackBat242 The Lone Star 12 September 18th, 2009 02:14 AM
A little bit of HP rocket news RandyT0001 Random Static 10 May 2nd, 2009 02:54 AM
COACC Rocket Engine atpollard MegaTraveller 105 January 24th, 2008 03:05 PM

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 - 2020, Jelsoft Enterprises Ltd.
Copyright (c) 2010-2013, Far Future Enterprises. All Rights Reserved.