Operating Time: Math Implications and issues to be aware of

[ShadowLogan]

The 2E RPG asserts that the VF-1 can operate for 48hrs, and the ASC VTs for 168hrs and the UEEF VFs for 336hrs (for those still using 1E, this is still an issue). If we take this to the implied conclusion that they can generate full thrust for that time one ends up with some ridiculous (and contradictory) space propulsion performance. We can also safely assume that all the VFs in the 2E (and 1E) RPG have T/W ratios of greater than 1, and sense T/W Ratio = acceleration measured in Earth Gravity we can do some simple math to work out what the "Delta-V" capacity of various veritechs (and other units) would be depending on their specific T/W Ratio and stated operating time. For simplicity I am only going to calculate the figures at 1G (to get a specific unit then multiply these numbers by whatever value the T/W is for specific units, for example the VF-1 T/W ratio is 3.47 so multiply the 48hr result by 3.47, though keep in mind this is the empty value and not loaded).

@1G for:
-048hrs = ~01,694.5kps
-168hrs = ~05,930.7kps
-336hrs = ~11,861.3kps

For comparison you only need ~9.4kps to launch into Earth orbit from the surface, with basically twice that you could IINM duplicate every propulsive maneuver of an Apollo Lunar Mission (by the Service Module, both Lander stages, and the 3 stages from the Saturn-V combined). Clearly some limits need to be placed on operating time in space form a propulsion standpoint or you end up with contradictions (SSTO) or game breaking features (and Life Support Endurance just will not cut it) that I don't think anyone really intended. I looked at 6minutes, 15minutes, 30 minutes (and did a 1G baseline as before, multiple the resulting figure as above based on the VF's T/W ratio) and this represents operating at FULL THRUST for the stated time (longer duration at lower thrust settings are possible, but the end delta-v is not going to change).

@1G for
-06min = ~03.5kps
-15min = ~08.8kps
-30min = ~17.7kps

All the Math done here is basically solving for a variable in the classic Acceleration = (Velocity-end - Velocity-start)/ Time formula (and if need be substituting in Velocity = Distance / Time) with Velocity-start being Zero. All figures are rounded to nearest 10th. I leave it to GMs to choose what they think works best for them (if you want to use a custom time you'll have to do the math).

On a side note, to give you an idea of how game breaking the propulsion system is as described, at 1G of constant Acceleration for 48hrs depending on planetary position you could travel from Earth to either Venus or Mars (with a wider window if you just want to fly by or have some other external means to "stop"). This doesn't change much aside from the window of planetary positions with either the standard VF-1 or any Alpha (two VFs with well known T/W ratios) based on their T/W ratio at full thrust for the duration. If the UEEF VFs had sufficient Life Support to operate at only 1G of acceleration for the duration of their operating time, they pretty much could range out to Pluto (not quite its max distance from Earth, but with 5% more acceleration, which they should all be able to do they could reach Pluto). If I did the T/W ratio right a VF-1 w/FAST Packs has a T/W Ratio of ~15, at that amount for 48hrs Earth-Saturn is covered (a bit short for Earth-Uranus actually, the main draw back here is if a person could sustain those G levels for the required time).

On a second side note I also calculated the acceleration of the big ships display per the 2E RPG. All figures should be viewed as approximate for several reasons: these are presented as rounded and the acceleration time may or may not be precise (but was taken as such, ex. of what I mean the writers could have rounded 46hrs or 50hrs to 2 days for simplicity).

Macross Saga Source Book:
-Orberth: 0.0900G
-ARMD: 0.0819G
-SDF-1: 0.0098G
-Zentreadi Flagship: 0.0158G
-Zentreadi Destroyer: 0.0211G

Masters Saga Source Book:
-Master Transport: 0.1629G
-Master City Ship: 0.0977G
-Tri-Star: 0.0791G

Genesis Pits Source Book:
-SDF-4: 0.0983G
-Icarus: 0.0733G

Average Acceleration Time is 0.0730G between these 10 ships (AFAIK these are the only ships in the 2E RPG with those ratings). IIRC Dialogue cues in TRM saga for a ship journey to the Moon, and assuming it is using constant thrust (ie acceleration) at 100% output the Tri-Star would need to be ~7x the existing value (which puts a trip at 12+ hrs, IIRC dialogue it is more like 5hrs) so the ship (and others potentially) might be able to sustain higher rates for shorter periods of time (as a possible explanation).

[Seto Kaiba]

The 2E RPG asserts that the VF-1 can operate for 48hrs, and the ASC VTs for 168hrs and the UEEF VFs for 336hrs (for those still using 1E, this is still an issue). If we take this to the implied conclusion that they can generate full thrust for that time one ends up with some ridiculous (and contradictory) space propulsion performance.

Eh... the reason that's ridiculous is because you're assuming (incorrectly) that Palladium's ruleset makes any real differentiation between atmospheric flight and space flight. It doesn't. Those runtime stats are atmospheric performance data only.

(You also have some errors in your T/W math due to inconsistent sourcing and differences in empty weight between the OSM and RPG, the latter of which tends to list things heavier. You're also going from empty weights, which is pretty misleading WRT fuel mass for things like FAST Packs.)

[glitterboy2098]

the UEEF equipment states that "heavy activity and combat reduces the fuel cells life in half". while exactly what counts as heavy activity isn't given, it seems likely that constant thrust interplanetary travel could count.

in addition, the robotech.com write up on the Alpha states: "However, the limited fuel tankage of this craft gives it short legs in space, a deficiency that led to the development of the Beta Fighter, to which this mecha can attach. In addition, the Alpha can not reach suborbital altitudes on its own, and also required the Beta for this."
indicating that the protoculture powered craft still carry some form of fuel tank for space operation. most likely this refers to reaction mass tankage. while the protoculture powerplant would provide electrical power to operate the many systems of the mecha, the engines are still basically rockets. they require some form of mass to expel to achieve thrust. in atmosphere this can obviously be just air sucked in by the intakes. but in vacuum it would have to haul reaction mass around inside the mecha.

note that this also would likely extend to the SLMH powered mecha. as those would be using their SLMH fuel for both the fusion powerplant providing electrical power, and as reaction mass used by their rocket engines to propel them in space. this would likely reduce their space environment operational time between refueling to only several hours for the VF-1 (which would help explain why they are refueled after every sortie.) presumably in atmosphere the engines can use air as remass, though given the lack of any design features to facilitate air intake at high mach numbers (such as the shock-cones seen on the SR-71) i would guess that even in atmosphere operations at mach 3 or higher would rely partly or wholly on their internal fuel tankage for remass. ASC veritechs and fighters, with their more efficient engines and resulting longer endurance would last longer, but would still operate much the same way.


as far as the spaceships go.. agreed that they probably don't fit details exactly. though the details in the show are easy to miss during a veiwing, and most game writers (or players) probably don't know enough math to reverse engineer such statements.

that said there are things that might help bridge the gap. it is possible to use creative orbital mechanics (such as oberth maneuvers and other gravity assisted effects) to gain more velocity than your engine specs alone would allow you to achieve.

[ShadowLogan]

Eh... the reason that's ridiculous is because you're assuming (incorrectly) that Palladium's ruleset makes any real differentiation between atmospheric flight and space flight. It doesn't. Those runtime stats are atmospheric performance data only.

I agree that is how Palladium works, and it isn't just in RT. The point I am trying to make is to show how ridiculous it is to make space flight an extension of the atmospheric flight model when taking the runtimes at face value (technically they do not say X time in space and Y time in atmosphere, which is the problem).

(You also have some errors in your T/W math due to inconsistent sourcing and differences in empty weight between the OSM and RPG, the latter of which tends to list things heavier. You're also going from empty weights, which is pretty misleading WRT fuel mass for things like FAST Packs.)

If we want to go granular detail like accounting for propellant mass and payloads you end up going the long way (using F=m*a formula) to get results that could be much easier to do with Delta-V equation. But as seen in the past, to get that level of detail currently is going to require varying levels of guess work. That though is not the purpose of this topic.

I agree the T/W math can be a bit misleading if you are not paying attention, but I DO call out in the (first) example that it is empty and not loaded. And by the math I would hope most people would realize that increasing the weight of the unit while keeping the thrust the same would lower the T/W ratio.

[Seto Kaiba]

I agree that is how Palladium works, and it isn't just in RT. The point I am trying to make is to show how ridiculous it is to make space flight an extension of the atmospheric flight model when taking the runtimes at face value (technically they do not say X time in space and Y time in atmosphere, which is the problem).

Ah, no... the ridiculous thing here is the entirely unnecessary point you're trying to make.

Nobody is coming to this game expecting realistic space flight mechanics. Palladium Books's ruleset has never made allowances for realistic space flight mechanics, and probably never will. It's what you'd call an acceptable break from reality, or a convenience feature. Players can focus on their thrilling space battle without having to bring along a CPA and a physics professor to micromanage the onboard propellant tanks of their fighter. It's more math than the overwhelming majority of players want to be doing when they play the game. The rules and the source material already pretty darn clear that these fighters can't fly the kind of long distances you're talking about, so why bother with additional unnecessary complexity? If the player wants to do something absurd, all the GM has to say is "you can't do that".

If we want to go granular detail like accounting for propellant mass and payloads you end up going the long way (using F=m*a formula) to get results that could be much easier to do with Delta-V equation. But as seen in the past, to get that level of detail currently is going to require varying levels of guess work. That though is not the purpose of this topic.

... you missed my point. Your math is just plain wrong, because you mixed-and-matched contradictory sets of numbers from the OSM and RPG to get your T/W numbers. The VF-1 and its FAST Pack, for instance, weigh more in the RPG than the OSM by a nontrivial margin. Some of your math is also misleading, esp. WRT the FAST Pack, since the rockets have MUCH less endurance than the main engines. You'll only have that higher thrust-to-weight ratio for about 2 1/2 minutes before you're out of fuel.

indicating that the protoculture powered craft still carry some form of fuel tank for space operation. most likely this refers to reaction mass tankage. while the protoculture powerplant would provide electrical power to operate the many systems of the mecha, the engines are still basically rockets. they require some form of mass to expel to achieve thrust. in atmosphere this can obviously be just air sucked in by the intakes. but in vacuum it would have to haul reaction mass around inside the mecha.

Yup. Unfortunately, it's not really clear how "protoculture-powered" engines even work... if they're just high-pressure ducted fans being direct-driven by a superconducting motor or if they're using an advanced heating element in atmosphere in order to operate as true jet turbine engines. In space, it's anyone's guess if they're operating as nuclear rockets they way fusion-powered mecha are or if they're using ion engines or something else.

note that this also would likely extend to the SLMH powered mecha. as those would be using their SLMH fuel for both the fusion powerplant providing electrical power, and as reaction mass used by their rocket engines to propel them in space. this would likely reduce their space environment operational time between refueling to only several hours for the VF-1 (which would help explain why they are refueled after every sortie.)

This is also correct. I've elaborated on this particular topic in a number of previous threads over the years. The short version is that the reactor uses the heat from the thermonuclear reaction to heat intake air in atmosphere as a replacement for a conventional jet engine's burner stage, while in space it operates like a thermonuclear rocket using plasma from the reaction as propellant. That rather naturally has severe implications for its fuel consumption and continuous operating time. OSM spec indicates it consumes fuel 4,200 times faster while producing maximum thrust in space, reducing a 700 hour atmospheric operating time to 10 minutes of engine burn at maximum thrust. This was supplemented with optional fuel bladders and, later, FAST Packs to extend that continuous max thrust operating time to over 30 minutes.

(I've recently completed several translations from Variable Fighter Master File which give very detailed explanations of how thermonuclear reaction turbine engines operate, how the technology improved over the years, and so on, so if anyone wants I can go into some fairly deep detail about that.)

[...] though given the lack of any design features to facilitate air intake at high mach numbers (such as the shock-cones seen on the SR-71) i would guess that even in atmosphere operations at mach 3 or higher would rely partly or wholly on their internal fuel tankage for remass.

There's actually a lot said about this exact subject in the latest volume of Variable Fighter Master File, Variable Fighter Master File: VF-1S Roy Focker Special. The translation is still a WIP, but it is noted that the "wedge" that sticks out between the main and sub intakes operates as a shock vane at supersonic speeds and there's some airflow manipulation done using the sub-intakes and the intake shutters on the main intakes. (An earlier volume also indicates there is a smaller sub-intake in the knee joint that can be opened to improve performance at high supersonic speeds.)

[ShadowLogan]

While I am not disputing the OSM might have an actual operating time that is available (either directly stated or can be derived), the RPG does not as the entry in the Manga size (pg74-7 in Macross Saga SB, IINM the full-size version is basically a C&P) omits anything like operating time information.

When I pulled T/W values for the VF-1 examples I pulled from a single source (your website), I did not mix match because there is nothing to mix and match as the information actually calculated for operating time and velocity changes ARE FOR A GENERIC 1 G system (ie T/W=1). That means one can easily adapt it to what ever specific mecha and sources and "house fixes" a GM wants to use as shown in the stock VF-1 example on how to do it.

Now you are correct the VF-1 w/FAST packs operating for 48hrs could be misleading because I am not factoring in payload mass, however the math assumes a constant acceleration rate which allows for the mass issue to be ignored (It's not realistic, but it is far simpler approach to work into an RPG). Now IF I DID consider payload (propellant and missiles) it would lower the T/W ratio*, but it is not likely to change the end result that a 48hr duration burn at maximum acceleration gives the mecha a huge operating range in terms of distance which the RPG probably does not intend. Which is the point I am making: that the lack of stated space operating time in the RPG at face value, as they want one to just substitute in the atmospheric time, leads to operating distance ranges in space that are not intended (GMs should be made aware of this, how they choose to "fix" it is up to them as the purpose of here is to identify the problem, how the GM "fixes" it is up to them as Palladium can not really do an "official fix" for the RT or Mac2 RPGs, they can fix it for Rifts/PW of course).

*and if you want to get technical the T/W would change as they consume propellant and discharge ordnance, all at varying rates. Going with a single T/W ratio and time at maximum is for RPG purposes probably a lot simpler, faster and easier to manage than going granular detail that would be right at home in a more technical source.

[glitterboy2098]

several of the entries for Protoculture powered mecha (such as the bioroid hoversled) refer to plasma drives, as do many of the spacecraft entries (interestingly, including the Oberth and ARMD which use SLMH fusion as their main powerplants), so i would guess that the Alpha, Beta, and other UEEF mecha use some form of Plasma drive. probably similar to a modern VASIMIR, but much more potent. VASIMIR uses microwave energy to convert fuel into plasma, and magnetohydrodynamic systems to accelerate the resulting plasma for thrust. it is one of the most powerful plasma thrusters IRL, and by its design can be used with all sorts of fuel as remass.. including things like compressed air. it would not be terribly hard to imagine that with access to room temperature superconductors and high efficiency microwave generators you could build a version of VASIMIR that could replicate chemical rocket level thrusts while still retaining the fuel efficiency of a plasma rocket and the fuel flexibility.

[Seto Kaiba]

While I am not disputing the OSM might have an actual operating time that is available (either directly stated or can be derived), the RPG does not as the entry in the Manga size (pg74-7 in Macross Saga SB, IINM the full-size version is basically a C&P) omits anything like operating time information.

Yeah, that's kind of my point... the game omits operating time information like that by design.

It's a deliberate omission meant to keep the gameplay flowing smoothly and easily. What you're doing here is just massively overthinking it. You're answering a question nobody asked, and that really doesn't need an answer.

When I pulled T/W values for the VF-1 examples I pulled from a single source (your website), I did not mix match because there is nothing to mix and match as the information actually calculated for operating time and velocity changes ARE FOR A GENERIC 1 G system (ie T/W=1). That means one can easily adapt it to what ever specific mecha and sources and "house fixes" a GM wants to use as shown in the stock VF-1 example on how to do it.

Ah, you've missed the point again I'm afraid... you mixed and matched OSM-based T/W ratios with RPG operating times. If you were doing this properly, you'd be drawing your information from one of those sources rather than both because they don't line up for some reason.

Palladium's stats make these mecha heavier for... reasons? For instance, Palladium's RT2E VF-1 is 15t not the OSM's 13.25t. That means its T/W ratio is 3.067 not the OSM's 3.472. The FAST Pack is also heavier in the RPG at 8t instead of 5.95t. Your math is, consequently, off.

Which is the point I am making: that the lack of stated space operating time in the RPG at face value, as they want one to just substitute in the atmospheric time, leads to operating distance ranges in space that are not intended [...]

Only if the GM isn't paying attention... the books themselves and the setting they're based on are pretty clear that these fighters aren't long-ranged craft in space. This ain't Star Wars.