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Effects of Scale on Maneuverability and Acceleration
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jmanski
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PostPosted: Tue Feb 12, 2013 7:19 pm    Post subject: Reply with quote

So the Millenium Falcon can go Space 9.6 unloaded? I'd like to argue that the Space listing is for an unloaded ship if that is the case. I mean the Falcon is supposed to be fast... but that fast??
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vanir
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PostPosted: Tue Feb 12, 2013 7:45 pm    Post subject: Reply with quote

If you go back over the last post you'll find the suggestion is the Falcon unloaded and empty has a move of space: 9, up from space: 8, but when loaded with full cargo holds it goes to space: 7.

Really doesn't seem much of a leap. Thing to remember though is the Falcon is extensively modified with military grade and highly customised equipment, despite a cargo capacity listing of 100 tons, according to the Tramp Freighters GG its actual usable cargo would be much less, probably half this. Meanwhile you could argue that it is also always moderately loaded due to these modifications comprising loaded equipment. So it probably can't actually go any faster but that'd be a case specific ruling.

You might say only lightly modified or unmodified ships could benefit from some parts of these rules, although theoretically they could still be overloaded using externally attached cargo pods.
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atgxtg
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PostPosted: Wed Feb 13, 2013 2:10 pm    Post subject: Reply with quote

jmanski wrote:
So the Millenium Falcon can go Space 9.6 unloaded? I'd like to argue that the Space listing is for an unloaded ship if that is the case. I mean the Falcon is supposed to be fast... but that fast??


It's just as valid a way of looking at it as the others. It has some merits too. It certainly helps the fighters keep their performance edge..Especially since most freighters would lose a point or two of SPACE speed due to cargo.

I'm not certain which method of the three I'd prefer. I think I lean towards the SPACE with a partial hold as I think it would be the easiest to implement, and probably result in the least amount of change to stats in play.

But the SPACE = empty speed view is just as valid.



Oh, and a few more pieces of the puzzle:

Realistically,. maneuverability sould adjust much the same way as SPACE. With identical ships, the one with less cargo would me more maneuverable. With most ships maneuverability pips is pretty close to SPACE speed.

This whole thing could be simplified into tracking a ship's cargo as light (up to one-third), moderate (up to 2/3rds) and heavy (over 2/3rds) with
set modfiers such as +1 SPACE +1 maneuverability

THis could also help a bit with modifying fighters. If we reverse engineer massess using SPACE speed and thrust in KTU, we can get a mass for more fighters and get an idea what the performance drop would be if you added more stuff to it. For instance, if an X-Wing masses 8.1mt (one way of doing the math), then upping the 4 laser cannons to heavy would add about 4 tons to it''s mass and reduce it's performance to 2/3rd what it is now (about SPACE 6, Maneuverability 2D).



Yet another consideration, especially with upping freighter SPACE and maneuverability is that the freighters probably weren't built for it. In the real world, with modern aircraft a pilot can easily pull a maneuver that stresses the vehicle beyond what it was designed for. A commercial jet liner might be faster than an old P-38 or Spitfire, but it's not designed to make snap turns at high speed.

In game terms too much maneuverability could risk damage tot he vehicle. This might be why TIE fighters have such relatively low maneuverability for their speed. Maybe if they pulled a #d+1 Maneuverability turn they'd rip the wing panels off.

But this is all just ONE way to doing this.
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CRMcNeill
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PostPosted: Wed Feb 13, 2013 3:30 pm    Post subject: Reply with quote

IMO, it would be less number intensive to simply cap a ship's maximum speed level based on load, so that a ship carrying more than a 50% load couldn't go All-out, a 75% load couldn't go faster than Cruising, and so on and so forth.
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jmanski
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PostPosted: Wed Feb 13, 2013 7:31 pm    Post subject: Reply with quote

That sits better with me.
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atgxtg
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PostPosted: Wed Feb 13, 2013 11:08 pm    Post subject: Reply with quote

Sounds good to me too! It even gets the proportional thing right without any more math.

How about we treat it as a temporary reduction in the number of moves a ship can make.?

That way if the ship takes engine damage in combat it will slow down further. That way a heavily burdened YT-1300 moving at high speed that takes an engine hit and loses 2 Moves will have to slow down.
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garhkal
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PostPosted: Thu Feb 14, 2013 4:22 pm    Post subject: Reply with quote

Agreed. Alternately, they can try to push themselves faster but each time doing so risks burning out the engines (Much like sometimes when you try to push a heavy car you may break the transmission)... Add a 'jury rig die' when you try to do so, and if both IT and the wild die come up a 1, you have damaged your engines.

I can also see having your 'weight' limits being a hamperer for maneuvering. The heavier you are, in full cargo, the less man you get (if any).
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jmanski
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PostPosted: Thu Feb 14, 2013 5:54 pm    Post subject: Reply with quote

Simple and elegant. I like.

How to do the maneuver dice, though? By percentage or a straight -Xd penalty?
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Raven Redstar
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PostPosted: Thu Feb 14, 2013 6:52 pm    Post subject: Reply with quote

Maybe do -1D per 33%? Which means a full load will knock off 3D maneuverability which kills pretty much any sort of transport, only the super modified ones will have a chance of having anything left.
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vanir
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PostPosted: Thu Feb 14, 2013 9:20 pm    Post subject: Reply with quote

That would mean if you bolted external cargo pods on, which overloaded the normal cargo to 150-200% listed value (these are available for the YT, it's in one of the books) what would you be left with performance wise, Space: 1 and -8D manoeuvrability? IIRC the external pods just reduce manoeuvrability and speed rating a little. And that's doubling your cargo capacity.

If you were going to place realistic limitations then you'd be talking about being restricted to a maximum of fast-cruising/military speed (no all-out) and maybe -1D manoeuvre at a full normal cargo load. No more. No way. And it would be a pilot induced limitation, not a physical one, that's how it works in aircraft IRL.

As for dynamic forces, it works counter-intuitively. Maximum induced G limitations for a structurally common mass load goes down with speed, not up (the faster you go the less manoeuvrable the craft must be). A fighter that can do 9G maneouvres at 400kts like an F-15 exceeds limitations at 7G transonic and maybe 5.5G supersonic. On top of that gentler manoeuvres induce higher lateral G loads. Really means maneouvrability is the most important thing for a pilot to watch when he loads up the plane with weight (listed as "g-restriction"). Yet still, something like an F-15 can handle those same induced-G limitations flying clean as it can with a warload, only at full combat load (iron bombs) it reduces and not that much, in fact G-restrictions for certain loads are because of the warheads having a maximum induced-G limit, not the aircraft. But those are warplanes. An F-16 doesn't actually have G-limits on warloads, not unless the weapons themselves have them (some do). Pylons, structure, all fine at 9G. And actually the nominal G limit on an F-15 is 8G subsonic but guidelines allow pilots to exceed it at around 400kts routinely with an "orange" (not "red") 9G.

Meanwhile acceleration is G loading but velocity doesn't have to involve any G-loads at all unless you turn.
This holds for aircraft and spacecraft but not groundcars because not every road is dead straight, for every bend, curve, turn or rise you load up the G on the vehicle. And it is G loads which is the issue with structural limitations, you have to lower your G-loads when carrying more to preserve structural integrity, it's got nothing to do with overworking the engine, which can't really happen so much in space because there's no resistance and in atmosphere because gravity alone trumps resistance (want speed, just dive). Accelerating against resistance however, like climbing against gravity, changing the rate of acceleration in a straight line (from standing still to moving forwards say), these are affected by weight/mass, but not velocity, it is pure drag versus thrust and nothing whatsoever to do with thrust versus weight (which is all about pure acceleration).

So for aircraft or spacecraft, in actual fact speed would not be affected by any load, only its acceleration and its manoeuvrability, but the reduction of manouevrability would be exponential to the G-load induced by velocity...once you turn. It is just safer to go slower if you're going to turn and have a big load. Doesn't affect speed capabilities.

Handled like an aerial pilot, you calculate the induced G for gentle manoeuvres at various loads. Reduce your speed enough for those to be manageable. It's not a physical speed restriction, it's a pilot choice regardless of the load.

By that as a measure, strictly speaking having had time to think about it overnight, I'd say performance isn't affected at all in spacecraft unless they are fullly loaded to the listed maximum cargo capacity, or overloaded with external cargo pods.
At 100% cargo, the pilot should only do gentle manoeuvres due to structural loading. It cannot affect speed capabilities, but will reduce acceleration/deceleration due to thrust vs mass.
At this stage it looks like I'm going with -1D manoeuvre at full cargo, and reduce acceleration/deceleration from 1/1 to 1/2.
When overloaded I'd further penalise both.
When completely empty I'll increase acceleration/deceleration to 2/1. The craft cannot become more maneouvrable since manoeuvre loss in the first place was pilot induced, not physically induced. And again speed capability is only affected by drag/thrust, not weight/thrust.
Pilots would be advised not to exceed a cruise or a fast-cruise speed when heavily loaded however, because when they turn with a big mass that will raise induced-G loading exponentially.
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atgxtg
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PostPosted: Thu Feb 14, 2013 10:12 pm    Post subject: Reply with quote

I'd say for the simplifed system use _1D per Move lost.
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atgxtg
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PostPosted: Thu Feb 14, 2013 10:21 pm    Post subject: Reply with quote

vanir wrote:
That would mean if you bolted external cargo pods on, which overloaded the normal cargo to 150-200% listed value (these are available for the YT, it's in one of the books) what would you be left with performance wise, Space: 1 and -8D manoeuvrability? IIRC the external pods just reduce manoeuvrability and speed rating a little. And that's doubling your cargo capacity.


Yeah, and I for one, would not do it that way. THe -1 Move and -1D maneuverability for a 50%+ full cargo hold presupposes that the cargo hold is about 25% of the ship's total mass.

So cargo pods that increased the ship's cargo capacity by 200% would only increase the overall mass by 50% and so should reduce speed and maneuverability by 2/3rds.

Simplified for the move lost method, if a full hold is -1 Move and -1D, then the equivalent of 3 full holds would be -3 Moves and -3D.

Of course with a stock YT-1300 that would still leave you with SAPCE 0 Maneuverability -0D, but at least the Falcon has some movement left with SPACE 5.


My rule of thumb would be -1 Move, -1D maneuver per multiple of the cargo space used. But since I thinking about the total tonnage, I'd have to adjust that a bit for ship's with fairly low cargo space. Obviously, going 100kg over the limit on an X-Wing won't mean nearly as much as going an exctra 100 tons over on a YT-1300.








If you were going to place realistic limitations then you'd be talking about being restricted to a maximum of fast-cruising/military speed (no all-out) and maybe -1D manoeuvre at a full normal cargo load. No more. No way. And it would be a pilot induced limitation, not a physical one, that's how it works in aircraft IRL.
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vanir
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PostPosted: Fri Feb 15, 2013 12:02 am    Post subject: Reply with quote

My point I took pains to explain fully, is that weight does not reduce speed.
The pilot reduces speed solely in order to reduce the induced-G from a higher mass than the original G rating for manoeuvring purposes.

It's about reducing g-loads, not about reduced performance. The only intrinsic performance loss to higher mass at the same thrust is acceleration, no other loss.

Manoeuvring is a form of acceleration (induced-G as opposed to normal G loading). And therefore actually higher mass has more effect upon the stresses involved in a given manoeuvre than it does on linear acceleration when talking about structural integrity.

What this means is pilot restricts manoeuvre by choice, to save the plane from breaking at higher loads. At the same loads acceleration is affected comparatively marginally but it is a physical effect of the load, the only affect of the load. The intrinsic manoeuvrability of the craft is not affected. The speed of the craft is not affected.
The pilot chooses to do softer manoeuvres and/or lower the speed of manoeuvres for structural reasons. The load doesn't affect them.

In game terms that means no complicated manoeuvres, and/or do not go at "all out" speed. That's it. And done by the pilot, not the craft.

What is affected is acceleration, meaning instead of 1/1 it has to reduce to 2/3 or 1/2 or something. I'd say it's less complicated just halving it. No other affect other than in RP terms, if a player goes "all out" fully loaded, roll hull damage against itself (as soon as he makes any kind of turn). Same if he does any "BFM" manoeuvres, ie. if he does anything in the craft other than an "easy piloting difficulty" manoeuvre fully loaded, roll hull damage against itself.

There are no other effects which are sound in physics terms, you have to study this stuff in prelimenary flight instruction. Been a long time, but it's coming back. Thrust vs drag for speed dude, not thrust vs weight that's acceleration.
The confusing part is because aircraft climbing is an acceleration (against gravity) not a speed thing.
In space changing mass doesn't affect an established speed if the same vehicle is accelerated there by the same engine, it just changes the inertia.




Mind you I'm only going on and on about it like this to unwravel my own head and strip it back to the basics, I have studied this and do have a handful of flying hours, but a long time ago. Although I'm still in the flight sim/aeronautics community and a lot of this stuff is also a part of that.
Anyways sorry if I'm seeming to be lecturing again, not the intention Smile
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garhkal
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PostPosted: Fri Feb 15, 2013 1:20 am    Post subject: Reply with quote

Raven Redstar wrote:
Maybe do -1D per 33%? Which means a full load will knock off 3D maneuverability which kills pretty much any sort of transport, only the super modified ones will have a chance of having anything left.


I can get behind that. Though would the -1d apply even if say the ship HAS no maneuverability dice?
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atgxtg
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PostPosted: Fri Feb 15, 2013 1:25 am    Post subject: Reply with quote

Cvanir,

technically we aren't referring to weight at all. We are referring to mass.

Secondly. the SPACE ratings in the RPG appear to be based on the ship's acceleration, not speed, and acceleration is affected by mass.

The reason why they use acceleration rather than top speed is because there wouldn't be a top speed in the sense we use it on Earth. Without an atmosphere, a ship could continue to accelerate as long as it had the fuel. So top speed would be a matter of acceleration and fuel efficiency.

A ship with a greater mass would simply take longer to reach a given speed and probably use more fuel to do so. Technically, a YT-1300 could probably go faster than an A-Wing if it had enough fuel and time.



As far as pilots reducing the G-loads of a maneuver by choice. That's not entirely true. Not all aircraft can take the same G-loading. Acrobatic craft like fighters are designed with higher maneuver load limits than cargo vehicles. There are a lot of restrictions and regulations in aircraft design that reflect this. Acrobatic aircraft require a much higher percentage of the aircraft';s mass be allocation to structure than a transport craft. So much so that a fighter simply can't have as much payload.

Something like a F-15 can make turns at higher G loads than something like a 747.
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