COACC Rocket Engine

[Wm_Humphrey]

Originally posted by TheEngineer:
What would You think about a kind of fusion ramjet, meaning turbines collect air, mixed up with the fusion stream and this mix is used as reaction mass ?

Have you ever seen the TV show Firefly? I thought it was very well done and - better yet - it just screamed "Traveller" at me. Too bad it was cancelled after the first season.

What you're suggesting seemed to be the principle behind the thruster pods on the ships in that show.

The principle of using more mass at a lower velocity to get the same thrust (thrust equals mass flow rate times exhaust velocity) with less power (exhaust kinetic energy 'power' equals one-half times the mass flow rate times the exhaust velocity squared) is why jet aircraft today use turbofan engines instead of turbojet engines. There's no reason I can think of why you couldn't take advantage of the same thing with a fusion rocket. In space, you want to maximize exhaust velocity to minimize propellant consumption. But if a big part of your propellant is essentially free from the atmosphere, it should reduce fuel consumption for the same thrust.

I've seen schematic conceptual designs of hybrid rockets which are essentially ramjets in atmosphere and rockets outside atmosphere. The really big bonus there is that you don't have to carry oxidizer for the portion of your flight in the atmosphere - which doesn't apply to a fusion rocket.

The possible drawbacks I see are 1) that you have a much more complex system if you include air intakes and 2) the innards of the fusion rocket, which normally only sees hydrogen, may not take well to the oxidizing quality of air. Both are practical matters, though, not show-stoppers in principle.

 

[Wm_Humphrey]

Originally posted by DonM:
Actually, I'd just like something I could use as errata for COACC and Hard Times for fusion rockets

If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

 

[Wm_Humphrey]

Originally posted by DonM:
Actually, I'd just like something I could use as errata for COACC and Hard Times for fusion rockets

If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

 

[Wm_Humphrey]

Originally posted by DonM:
Actually, I'd just like something I could use as errata for COACC and Hard Times for fusion rockets

If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

 

[atpollard]

Here is the data for the TRITON Rocket Engine I mentioned earlier. I found it very interesting and thought that you might like it. Gotta' love R&D at Pratt & Whitney Rocketdyne.

 

[atpollard]

Here is the data for the TRITON Rocket Engine I mentioned earlier. I found it very interesting and thought that you might like it. Gotta' love R&D at Pratt & Whitney Rocketdyne.

 

[atpollard]

Here is the data for the TRITON Rocket Engine I mentioned earlier. I found it very interesting and thought that you might like it. Gotta' love R&D at Pratt & Whitney Rocketdyne.

 

[Space Cadet]

Originally posted by atpollard:

Handwavium no 1043: Only with the discovery of the elusive relationship between gravitons and tachyons, is fusion and anti-gravity possible. The fusion rocket expels a tachyon exhaust which is no longer limited by the speed of light and is thus able to produce the feats of propulsion engineering that have always been the halmark of the Third Imperium spacecraft. Note that although it is perfectly safe to stand behind a tachyon exhaust while it is running, there is some danger in walking in front of a tachyon exhaust, since you could cross the path of where the tachyon will be at some future time as it travels backwards through time.

Or maybe not.

If Tachyons exist in the Traveller Universe, then you could have FTL communications, which is a big no no in the Traveller Universe.

 

[Space Cadet]

Originally posted by atpollard:

Handwavium no 1043: Only with the discovery of the elusive relationship between gravitons and tachyons, is fusion and anti-gravity possible. The fusion rocket expels a tachyon exhaust which is no longer limited by the speed of light and is thus able to produce the feats of propulsion engineering that have always been the halmark of the Third Imperium spacecraft. Note that although it is perfectly safe to stand behind a tachyon exhaust while it is running, there is some danger in walking in front of a tachyon exhaust, since you could cross the path of where the tachyon will be at some future time as it travels backwards through time.

Or maybe not.

If Tachyons exist in the Traveller Universe, then you could have FTL communications, which is a big no no in the Traveller Universe.

 

[Space Cadet]

Originally posted by atpollard:

Handwavium no 1043: Only with the discovery of the elusive relationship between gravitons and tachyons, is fusion and anti-gravity possible. The fusion rocket expels a tachyon exhaust which is no longer limited by the speed of light and is thus able to produce the feats of propulsion engineering that have always been the halmark of the Third Imperium spacecraft. Note that although it is perfectly safe to stand behind a tachyon exhaust while it is running, there is some danger in walking in front of a tachyon exhaust, since you could cross the path of where the tachyon will be at some future time as it travels backwards through time.

Or maybe not.

If Tachyons exist in the Traveller Universe, then you could have FTL communications, which is a big no no in the Traveller Universe.

 

[Wm_Humphrey]

Originally posted by Wm_Humphrey:
If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

So much for "tomorrow"!

Had an attack of real life and this got back-burnered. Still working on it, though.

Turns out I already have the CD for MT - what a thing to forget! Also turns out I had started just such a table for myself quite some time ago but never finished it.

 

[Wm_Humphrey]

Originally posted by Wm_Humphrey:
If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

So much for "tomorrow"!

Had an attack of real life and this got back-burnered. Still working on it, though.

Turns out I already have the CD for MT - what a thing to forget! Also turns out I had started just such a table for myself quite some time ago but never finished it.

 

[Wm_Humphrey]

Originally posted by Wm_Humphrey:
If I have some time tomorrow, I'll try to post a proposal for a modified "Table 5a - Engines" from Hard Times. (I still can't find my copy of COACC - maybe I need to get the CD from Marc.)

So much for "tomorrow"!

Had an attack of real life and this got back-burnered. Still working on it, though.

Turns out I already have the CD for MT - what a thing to forget! Also turns out I had started just such a table for myself quite some time ago but never finished it.

 

[atpollard]

I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

 

[atpollard]

I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

 

[atpollard]

I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

 

[Wm_Humphrey]

Originally posted by atpollard:
I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

The main reason COACC doesn't have volume numbers is because aircraft are mass-limited and are very volume-intensive when assembled due to pesky factors like aerodynamics, lifting surfaces, stabilizer surfaces, etc. Volume isn't a primary concern. Even an "airframe" configuration from the basic craft design rules isn't, IMO, a true aircraft capable of generating aerodynamic lift far in excess of its own weight and operating normally with a thrust-to-weight ratio less than one. It just means that it's not a brick, streamlined or otherwise, and failure of the grav generators doesn't equal immediate catastrophe. (All Darrian grav vehicles are airframe configurations!)

My relatively uninformed opinion about FF&S (I don't own it) is that it is for far more dedicated gear-heads than I. I want a slightly higher-level approach that gives me trade-offs in the design process, is consistent, has the appropriate "Trav" feel, and can design a basic grav vehicle or starship by hand with no more than two sheets of paper. My detail-nitpick mode is only activated by things that cause my disbelief to unsuspend - like fuel consumption numbers for reaction drives that require super-luminal exhaust velocities. I can handwave around reactionless thrusters and the fact that you could demonstrate that they violate the principle of conservation of energy. I accept this flaw firstly because that would only come into play when ships reach insane velocities and secondly because I don't know that it won't work. But I'm getting off-topic...

One of the few elements of T4 that I liked was the notion of a two-tiered approach with the Quick Ship Design System (QSDS) and Standard Ship Design System (SSDS) for ship design. If you just want a basic ship, you use the faster, simpler system; when you've got time to kill or some specific goal in mind, you can dig down to the next greater level of detail. Of course, it fell down completely for me when I discovered that you could not, in fact, use the "pieces" in the SSDS to replicate the "modules" in the QSDS. But this too is a topic for a different forum...

 

[Wm_Humphrey]

Originally posted by atpollard:
I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

The main reason COACC doesn't have volume numbers is because aircraft are mass-limited and are very volume-intensive when assembled due to pesky factors like aerodynamics, lifting surfaces, stabilizer surfaces, etc. Volume isn't a primary concern. Even an "airframe" configuration from the basic craft design rules isn't, IMO, a true aircraft capable of generating aerodynamic lift far in excess of its own weight and operating normally with a thrust-to-weight ratio less than one. It just means that it's not a brick, streamlined or otherwise, and failure of the grav generators doesn't equal immediate catastrophe. (All Darrian grav vehicles are airframe configurations!)

My relatively uninformed opinion about FF&S (I don't own it) is that it is for far more dedicated gear-heads than I. I want a slightly higher-level approach that gives me trade-offs in the design process, is consistent, has the appropriate "Trav" feel, and can design a basic grav vehicle or starship by hand with no more than two sheets of paper. My detail-nitpick mode is only activated by things that cause my disbelief to unsuspend - like fuel consumption numbers for reaction drives that require super-luminal exhaust velocities. I can handwave around reactionless thrusters and the fact that you could demonstrate that they violate the principle of conservation of energy. I accept this flaw firstly because that would only come into play when ships reach insane velocities and secondly because I don't know that it won't work. But I'm getting off-topic...

One of the few elements of T4 that I liked was the notion of a two-tiered approach with the Quick Ship Design System (QSDS) and Standard Ship Design System (SSDS) for ship design. If you just want a basic ship, you use the faster, simpler system; when you've got time to kill or some specific goal in mind, you can dig down to the next greater level of detail. Of course, it fell down completely for me when I discovered that you could not, in fact, use the "pieces" in the SSDS to replicate the "modules" in the QSDS. But this too is a topic for a different forum...

 

[Wm_Humphrey]

Originally posted by atpollard:
I was looking at the COACC engines and the HARD TIMES engines and comparing them to the MT REFEREE engines. COACC has no sizes (volume) and very different rules for determining craft volume than the other MT books (20xMass if disassembled and 60xMass if assembled). I look forward to what you come up with.

Does anyone know if "Fire, Fusion and Steel 1" will help? I am waiting for the TNE CD to get it.

The main reason COACC doesn't have volume numbers is because aircraft are mass-limited and are very volume-intensive when assembled due to pesky factors like aerodynamics, lifting surfaces, stabilizer surfaces, etc. Volume isn't a primary concern. Even an "airframe" configuration from the basic craft design rules isn't, IMO, a true aircraft capable of generating aerodynamic lift far in excess of its own weight and operating normally with a thrust-to-weight ratio less than one. It just means that it's not a brick, streamlined or otherwise, and failure of the grav generators doesn't equal immediate catastrophe. (All Darrian grav vehicles are airframe configurations!)

My relatively uninformed opinion about FF&S (I don't own it) is that it is for far more dedicated gear-heads than I. I want a slightly higher-level approach that gives me trade-offs in the design process, is consistent, has the appropriate "Trav" feel, and can design a basic grav vehicle or starship by hand with no more than two sheets of paper. My detail-nitpick mode is only activated by things that cause my disbelief to unsuspend - like fuel consumption numbers for reaction drives that require super-luminal exhaust velocities. I can handwave around reactionless thrusters and the fact that you could demonstrate that they violate the principle of conservation of energy. I accept this flaw firstly because that would only come into play when ships reach insane velocities and secondly because I don't know that it won't work. But I'm getting off-topic...

One of the few elements of T4 that I liked was the notion of a two-tiered approach with the Quick Ship Design System (QSDS) and Standard Ship Design System (SSDS) for ship design. If you just want a basic ship, you use the faster, simpler system; when you've got time to kill or some specific goal in mind, you can dig down to the next greater level of detail. Of course, it fell down completely for me when I discovered that you could not, in fact, use the "pieces" in the SSDS to replicate the "modules" in the QSDS. But this too is a topic for a different forum...

 

[atpollard]

Originally posted by Wm_Humphrey:
The main reason COACC doesn't have volume numbers is because aircraft are mass-limited and are very volume-intensive when assembled due to pesky factors like aerodynamics, lifting surfaces, stabilizer surfaces, etc. Volume isn't a primary concern.

I understand WHY they ignored volume, but an unintended consequence is that I cannot use a COACC Turbojet Engine to power a air cushion vehicle or provide a 'hotrod' boost to an air raft without creating my own volume ... and COACC seems to have ALL of the air breathing engines.

Hard Times is a gold mine of Rocket Engines to install in other vehicles (once you zoom in and squint enough to read it on the CD.)

Even an "airframe" configuration from the basic craft design rules isn't, IMO, a true aircraft capable of generating aerodynamic lift far in excess of its own weight and operating normally with a thrust-to-weight ratio less than one. It just means that it's not a brick, streamlined or otherwise, and failure of the grav generators doesn't equal immediate catastrophe. (All Darrian grav vehicles are airframe configurations!)

I remember seeing more detailed rules on wings and airframes somewhere (it might have been the old Striker). I agree that the MT airframe is a very abstract system, but I have a great deal of sympathy on this issue. How can you develop a simple rule to cover everything from the long slender wings of a glider, the wings of a Cessna, the wings of an F4 Phantom, the wings of a Stealth Bomber and the wings of a Hypersonic Orbital space plane? THAT would almost require a book of it's own that would leave people longing for the simplicity of FF&S.

A set of guidelines for generating wings for different airframes with the effect on maximum and minimum airspeed might be nice, but that should appear in some place like STELLAR REACHES instead of filling the basic rule books. Unfortunately, such a task is well outside my expertise - I would do a poor job of identifying what attributes are important to realism and what is unnecessary complexity. (Although speed and wing area do appear to be inversely related).