Chapter 1: frame, etc p17 Rotor Volume. Helicopter rotors need area based on lift, not volume based on size. Give rotors a volume of power^(3/2) / 5000. If you _really_ care, make lift equal to (power^2/3) * (rotor area ^ 1/3) * 20 * (multiplier for rotor type). p18 Living Metal (TL 13+) and Biomechanical structure (TL 9+) Living metal is pretty cinematic to begin with, but these rules don't make any sense -- how can a living metal _frame_ reconstruct portions of the vehicle which are not living metal? Apply the living metal multiplier to _all_ components made of living metal, not just the frame. In addition, nanites require a source of replacement mass, a power source, and are not entirely massless. Multiply weight and volume of living metal components by 1.25, add a power requirement of 1 kW/ton for biomechanical structures and living metal which is not engaged in repair. For living metal which is engaged in repair, multiply by 10 for regular regeneration, 600 for fast regeneration, and 36000 for instant regeneration. If a biomechanical structure loses power it will lose 10% of its HP per day and eventually die; living metal will shut down, and will require at least 10 kWh/ton to awaken. p18a Frame weights Frames can reasonably amount to up to around 100 lb/cf of vehicle volume, though this will noticeably affect volume for light weight frames. Simply multiply cost and hit points by the same multiplier as was applied to the frame weight. p18a Frameless vehicles. At any TL, a vehicle may be constructed without a frame. A frameless vehicle cannot have a drivetrain, or any other subassembly which would normally require an attachment to a rigid frame; this is basically for construction of body suits. You must have nonrigid armor to hold the frame together -- DR 1 nonrigid or reflex is generally sufficient. p18a Field-reinforced Frames (TL 11+) The vehicle frame has been reinforced with force or deflector fields. Increase frame weight by 20%, cost by 100%, and add a power requirement of 0.01 * (volume) * (HP modifier for frame weight). When power is on, double vehicle hit points. p18a Option: energy frame (TL 12+) As above, but the vehicle is naturally frameless. Frame weight is 1/5 normal, power requirement is as above. Decide if the vehicle will have any surface features; if so, give it a nonrigid frame (as if it were a frameless vehicle) which will be held rigid by the force fields. Otherwise, simply give it a deflector field (if you want it to be sealed) and/or a force screen. p19 Frame Weight Realistically, the percentage of a vehicle's weight which is frame goes _up_ as it gets larger, not down. Compute frame weight from volume, not surface area (any subassembly with a surface area multiplier also multiplies its volume, for purposes of frame weight). All other stats remain based on area. p20a Forcelock Compartmentalization (TL 12+) Rather than having heavy doors to enforce compartmentalization, you can use forcelocks. This adds 0.001 lb per cf, cost $100/lb, and draws 0.1 kW per lb (only if in use), and gives the same benefits as partial compartmentalization. p22 Nonrigid armor Nonrigid armor has a max DR of (TL+1)*2 according to Robots; since this makes TL 8 heavy monocrys armor impossible, I prefer (TL-3)^2. If nonrigid armor is layered in such a way that it does not have a fairly soft surface behind it (such as flesh), halve its DR. p22 Ablative armor Ablative armor is highly optimistic, but also somewhat broken. Halve DR of armor, DR is reduced by 1 per sqrt(area) damage. p22a Thermal-optimized armor Armor can be designed specifically to protect against heat. Take any form of composite or ablative armor and reduce DR by 25%; DR is doubled against any heat-based attack (same as thermal-superconducting). p22a Field-Reinforced armor (TL 11+) Much as a frame can be reinforced by force screens/etc, armor can also be reinforced. Buy as metal armor at 5* cost, add a power requirement of 0.001 * DR * area. When active, DR is doubled, and treat as laminate armor. This could also represent collapsed-metal screens, which require some form of gravetic generator to remain stable -- this has only 1/10 the power requirement, but is destroyed if power is lost. Optionally, TL 11 laminate armor might just be collapsed-metal, with a power source built into the armor. p23 Advanced Armor Most vehicles are not perfect cubes. As a rule of thumb, assume that each end represents 10% of the area, each side is 15%, the top and bottom are each 25%. p23a Armor Volume Armor does have some volume; use weight/500 for metal or laminate armor, weight/50 for wood or nonrigid, weight/100 for other armor types. Adds volume * 62.5 lb to floatation, except for nonrigid armor, which doubles in weight when wet. If you have enough armor volume, the need to fill 'corners' of the armor will reduce DR slightly, though for most vehicles this can be ignored. Find the volume ratio, R (total volume / internal volume); multiply DR by 3 * (R^1/3 - 1) / (R-1). p26a Blowthrough on a vehicle occurs at (hit points)/(volume)^1/3. p26a HT of vehicles. The HT curve is rather strange. I prefer to take (hits)/(tons)*2, and look up this number on the range/speed table to get actual HT. This requires somewhat more HP to get HT 12, and in general you can assume that +1 size (with no change in frame) will give -1 HT. Chapter 2: motive systems p31 The efficiency gain for large drivetrains is much lower than these tables would suggest; I assume the intent was to keep small vehicles from moving at lightning speed. A better way of doing this is to fix the performance table. I would like to give drivetrains a 'ST' score instead of a power requirement at all, but haven't yet found a good way to do so. p33a The thrust of a fan is approximately proportional to power^1/2 * area^1/4, which makes larger fans less efficient. The fans here are an average case, significantly faster and slower fans are possible. p35 Hyperfans are capable of speeds above 2000 mph. p35a Add: scramjet(TL8) Weight = Thrust/10+100. Fuel = 0.2H. A scramjet is only operational at speeds in excess of 2000 mph, you must have another form of thruster to reach that speed. Chapter 3: weapons p45 super-stabilized weaponry For extremely sensitive equipment, the level of stabilization provided by 'full stabilization' might not be enough. For every additional +1 to stabilization, double weight and cost. p46 PAW periscope While not as simple as a mirror for a laser, a CPAW or NPAW can generate a beam in one location and pass it through an evacuated tube to where it hits a secondary magnet. This is 25% of the weight and cost of the weapon system associated with it, and is otherwise identical to a laser periscope. p46 Cyberslave mounts A cyberslave mount may be treated as a universal mount instead of as a casement mount; this is mostly useful in turrets. Chapter 4: electronics p50-54 Scan Sensor 'range' is nowhere near linear in mass. Halve scan and add TL, with the following exceptions: apply an additional -2 for sonars. Treat TL as 5 for the unusual sensors (madscanner/etc). See M.A. Lloyd's rules for the scan of LLTVs. Any sensor with a scan greater than 10 requires a sensor operations program, with a complexity of (scan-10)/2 -- if you do not have sufficient computer power give the sensor a split scan (use the computer value for locating, the second value for improving contact). p52 Radar: add 'Rainbow Ladar: TL 9'. Rainbow ladar can be useful for detecting concentrations of elements by scanning for absorbtion bands (such areas will appear dark). This may be default for TL 9 ladars; if not, double cost. p54 Add 'multi-object spectroscope' (TL 8 or 9). This is a sensor capable of doing instant spectral analysis on objects within its range. At TL 8 it is limited to a few hundred points, and thus is only useful in space; at TL 9 it is useful on a planet. This doubles the weight and cost of any optical imager; it is usually applied to PESAs. This is one of the realistic versions of the chemscanner. You can get partial versions of this effect at TL 6 by using filters -- the advanced TL is due to the ability to do simultaneous detection and analysis. p55 The weights for high-power sound detectors are severely understated. A basic sound detector has a Scan equal to TL (the human ear has a Scan of 4); this may be increased like any other sensor -- so +3 Scan is x10 weight. For reference, Scan will shift noise levels by +5 dB*(scan-4). p55 The sound loudness table is totally wrong. Among other things, decibels aren't a measure of sound emission (they're a measure of sound intensity). p56 Note that it takes 600 hours minimum to fully survey an earthlike planet, due to the time requirements for doing a full pass. A PSA can be used to map a planet, and will detect objects of size at least (22 - 2 * TL); count a medium array as +1 TL, heavy as +2 TL. A PSA is normally an _active_ sensor (including a synthetic-aperture radar), it will generally require multiple passes to generate a full map without use of radar, and will not give anywhere near as good vertical resolution. p57 Any communicator may be configured to act as an IFF, add $1000 at TL 7, halved at each additional TL; alternately, IFF software is Cx1, $1000, TL 7, for a computer. The standard IFF is a medium-range tight-beam radio. It would be possible to make an IFF which could also be used as a regular communicator, but it cannot be used in both modes at once, so normally this is a dedicated device. p59 Deceptive jammer stats are also appropriate to various other forms of active cancellation (usually applied to radar and to sound dampening); you can also get the equivalent of deceptive jammers for sound. A deceptive jammer can also be used to increase the apparent size of an object -- a deceptive jammer may appear as an object of up to (jam rating + 4) size. However, jammers are less effective on larger vehicles -- subtract (size-4) from jam rating. p60 Robot Brains DX is equal to Complexity + 5. p62a Software * Skill levels: for programs which provide a skill, +1 complexity gives +2 skill. For programs which give a bonus to a skill, +1 gives +1. Skill programs: a skill program gives an Easy skill at (C*2+4), an Average skill at (C*2+3), a Hard skill at (C*2+2), and a Very Hard skill at (C*2). Neural-net gives +1 to Mental, AI gives +2. Increased DX (per robots) adds to Physical skills. * Running at higher Complexity: many programs can be allocated more resources than they normally use. Running at +2 complexity will generally cause the program to work as if written at +1 complexity. * Running at higher speed: give a program +1 complexity to run in and it can also accomplish tasks in 1/10 normal time. This is generally only useful on mental tasks, physical tasks require the system being controlled to also be adapted. * Gunner program: Gunnery programs add Acc to skill even on a snapshot. The skill of the Gunnery program should also be used as a general 'recognize foe' skill. * Program: Image Enhancement. Cx2, $2000, TL 7. Adds Complexity to your electronics operation skill levels. Chapter 5: Miscellaneous Equipment p65 Arm Motor Table. Realistically, multiply weight, power requirement, etc, by the reach of the arm (in hexes). Arms generally have a minimum reach of (volume)^1/3. p65 Fire extinguishers. Stats are per 10,000 cf. p66 A ST 10 winch shouldn't normally weigh 50 lb, but shouldn't retract at the listed weight either (in fact, it violates conservation of energy for it to do so). Divide weight by 10, retracts at 1 yard/sec, power requirement is .05 kW * ST. For a high-speed winch, divide ST by the multiplier for retraction speed. p66 Tractor, Pressor, and Combination beams could probably be designed as beam weapons (see weapons design). It is unclear why the base weight of 1 ton, this will be ignored. p70 Forcelocks can be constructed _without_ safety doors, this is probably only done for emergency internal compartmentalization. See 'forcelock compartmentalization' in chapter 1. p70 Brigs are 50% access space, like all cabins. The internal area of a cabin-sized brig is 240 sf, in case you want to armor it (or apply other surface features); assume the brig has DR 5 for free. Chapter 6: Crew and Passengers p77 Many SF novels, movies, etc, assume that cabins on a spaceship are similar in size to hotel rooms. This is roughly 4x the listed volume. This is appropriate for Traveller starships, for example. p77 Cabins can be given surface features. Half the volume of quarters is assumed to be access space (passages, etc), compute the surface area of the cabin based on only half the actual volume. Like brigs, assume cabins have DR 5 for free. Chapter 7: Power p82 A significant fraction of the weight of any steam engine is in water. Reduce the weight of an empty steam engine by 20%. In addition, add a water requirement equal to the fuel requirement, but assume that the steam engine includes enough water to run for an hour without any extra water. p87 Electric Contact Power The weight for an electric contact power plant can also be used per 100' of wire or track, which is useful for maintenance robots. Maintenance robots require 1' of track per 10 cf of access space. p87 Energy Banks As others have noted, the energy density for GURPS power cells is insane. I favor an energy density of (3600)*(TL-6) per lb instead of 9000*. This has the virtue of being actually _more_ consistent with existing GURPS tech than the value listed in Vehicles (it corresponds to the energy density of B, C, and D cells) -- only equipment which uses E cells (which will now weigh 50 lb) need be modified. Chapter 8: Surface Features p91 Stealth/IR/emissions/sound. The stats for 'radical' cloaking are wildly optimistic. Rather than having 'radical' cloaking give double the signature reduction, I give it only (TL-2) -- i.e. two better than basic cloaking. For $1000($300 for sound) and 3 lb/sf, you can have 'intermediate' cloaking which subtracts (TL-3). Optionally, further levels of camoflage are available, assume each extra -2 to detection is x10 cost. p91 Ultrablack. In space, you don't need chameleon systems -- just paint the ship black. Any stealth vehicle may be painted black at no charge, and will apply its stealth against vision in space (it will act as normal black paint on a planet). For 10% of the cost of stealth and negligible weight you can have ultrablack paint with no other features. In addition, basic chameleon acts as basic stealth, instant acts as intermediate stealth, intruder as radical stealth. p92 Use TL 7 stats for radiation shielding, regardless of TL; these stats assume mixed radiation, it will be essentially worthless against pure high-energy gamma radiation. Chapter 9: Weapons p104 KE damage While for large weapons penetration is roughly proportional to mass density * velocity, somewhat different factors come into play for small caliber rounds, where you cannot treat targets as ductile; this generally reduces the effectiveness of tiny MD rounds. Multiply KE damage by 0.4 * sqrt(B) for rounds of < 6.25mm. p105 Max Range The sudden cutoff in range at 6mm on range is weird. For rounds < 6.25mm, use 0.4*B instead of sqrt(B), and keep the *375 multiplier for all calibers. p106 Weight (conventional guns) The formula for 'S' (based on bore size) has odd breakpoints and doesn't wind up working for extremely large weapons anyway. S is equal to B/100 with a minimum value of 0.25; replace with S/200 for low-velocity rounds, S/400 for very low velocity rounds. p106 Weight (electromagnetic guns) Weight should probably go up as a linear function of energy used, at least for large-caliber rounds. Multiply weight by (B/20) for cannons. p107 Sustained RoF Most weapons will eventually overheat if fired at the maximum RoF for the weapon. Maximum sustained RoF is measured in rounds per _minute_, and need only be applied to autofire weapons. For light automatic weapons, it is 2000/B with a max of 200, for heavy automatics it is 10000/B with a max of 500, for gatling guns it is per heavy automatic, multiplied by the number of barrels. p108 Weight per Shot The listed values for P only apply to conventional ammunition, as the weight of the ammunition case drops very rapidly with reduction in bore pressure, 'very low power' rounds are functionally caseless at TL 7. For other weapon types, P is 0.4 for very low power rounds, 0.7 for low power rounds. p112 Ammunition Stats (needlers) Due to the suggested reduction in range/damage for low-caliber KE rounds (see above) change needle/HVS rounds to use *1 for damage, superwire to use 0.4. p112 Space Combat Missiles The endurance of a space-combat missile is log(missile weight/warhead weight)*specific impulse/Gs; it is actually slightly lower than this due to structural requirements. The solid-fuel rocket stats don't actually improve past TL 8, which is not supported here. I suggest using log10(MW/WW) *(TL-3)*160/Gs -- this roughly matches solid fuel rockets at TL 7, and while optimistic at higher tech levels is far less so than power cells. p112 Space-Surface Missiles (thor strikes) An object hitting atmosphere in free movement will halve its velocity roughly every (terminal velocity)^2/16 yards; for a missile this works out to roughly 3.5 miles * (weight)^1/3, though a hardened penetrator could have 5x this range (can only be AP or APHD -- APDU will burn, no other warheads are dense enough). While the actual height of the atmosphere depends on how you compute it and is fairly high, it can be treated as being (surface pressure)*6 miles deep; the actual amount of atmosphere which must be penetrated is (apparent height)/cos(angle). A truly high- velocity impact can cause a shockwave like a conventional explosive -- treat as if the explosive damage is roughly (weight)*(speed/1000)^2 dice. Otherwise, treat as a normal missile hit. Thor strikes are generally treated as artillery or guided missile strikes from ranges of 200+ miles. p113 Explosive rounds Change X from B*B*B to B*B*40, this brings the damage of explosive rounds in line with the typical hit points of vehicles, and leaves grenades with roughly their current stats. Ignore the special rules for rounds < 20mm. p117 Missile Endurance The rules for missile endurance are moderately broken, too low for small missiles and too high for really large missiles. It is also more than a little bit complicated to actually compute, because acceleration rises as fuel is burned off, while drag does not change. A simplified way of handling this (close enough for most purposes): a) Determine propellant weight as a % of vehicle weight. Multiply by (TL-3). Choose a speed, no greater than 5x this number. b) Subtract (speed/10) from this number -- this is the fuel required to reach maximum velocity. c) Divide by (speed)^2/100,000 d) Multiply by (weight)^1/3. Minimum speed is 100 * (weight^1/3). p124 half damage range in space The figures for lasers are physically impossible. Divide listed space ranges for all lasers by 5. N-PAW range multiplier for space should be *10 (not *50, as errata'd). p126 Accuracy I favor halving all computed Acc numbers, and ignoring the 'Acc cannot exceed skill' rule for vehicular weapons. Acc in space should be recomputed. Beam weapons do not lose Acc beyond half damage range. p123-127 Energy Weapons Additional types of energy weapons are: S-PAW(TL8): a high-energy N-PAW optimized for high particle energy and low beam current. Not useful in atmosphere. For damage, B is 0.8 with an armor divisor of 2. For range, B is 3 with *100 range in space (*500 if not reducing range as noted above). For weight, B is 32. Other stats per N-PAW. Delivers 10 rads/pt damage on hit. SA-PAW(TL9): An antimatter PAW without any capability of creating an evacuated tube in atmosphere. Requires an antimatter storage bin -- uses 1e-9 grams of antimatter per KJ per shot. B is 4.0 for damage with an armor divisor of 2 and secondary explosive effects per an A-PAW. For range, B is (nil) in atmosphere, 150 in space. For weight, B is 32. For cost, B is 2.0. For power, B is 2.0. Fusion-Boosted weapons(TL9): plasma weapons over 1 megajoule can be redesigned to use a microfusion pellet instead of direct power input. Divide power requirements by the square root of energy in megajoules, double cost. Pellets are roughly 0.0001*sqrt(energy) grams. Can be added to plasma blasters (UT2) and flamers. Automatic for fusion guns. Chapter 10: Performance The way handling is handled in this chapter makes a number of assumptions which really aren't accurate -- almost all the speed computations use bogus math. Unfortunately, non-bogus math winds up being grossly complicated. p128 Ground Speed As noted by M.A. Lloyd, the power requirements are totally absurd, he suggests as more realistic P(kW) = (Adr/4) x (mph/100)^3 + (Lwt/speed factor x10) x (mph/100); congregating constants this works out to (Adr * mph^3)/40,000 + (Lwt*mph)/(speed factor * 100000). This is not exactly a beautiful equation. It also isn't even correct, as the main form of static drag which a small vehicle encounters is not from the wheels (and thus weight-based), but from the drivetrain (and based on the size of the drivetrain. In addition, the primary limitation on legged drivetrains is the velocity the leg can achieve, which is mostly a function of leg ST. I am tempted to give drivetrains a ST rather than a power requirement, but haven't come up with a good method for doing so. p135 Aerial Top Speed There are some significant problems with these equations, because they don't identify _why_ certain types of motive systems have top speeds. In fact, ducted fans (as listed here) violate conservation of energy at speeds in excess of 120 mph -- if you multiply ducted fan thrust by (200/(200+mph)) you get closer. Of course, that's suddenly horrible to solve for. As a simplistic method of handling this effect, it is worth trying this: for all air-breathing engines, add a constant to drag (which is _not_ reduced by streamlining) equal to thrust/X, where X is: 20 for fans or rotors, 1000 for most jets, 5000 for ramjets, turboramjets, hydrogen burners, and fusion air-rams. This does put a hard limit of 387 mph on ducted fans and helicopters -- higher-speed fans could go faster, but would have higher power requirements. p135 AMr There is absolutely no reason why vector thrust vehicles should have anything like the suggested AMr. AMr for vector thrust will be equal to AAcc / 20. The AMr for winged vehicles tells you when the wings will fall off, which is a useful concept. However, MR is also limited to 1.0 * (speed/stall)^2. This means a winged vehicle has a minimum turning radius, equal to (stall^2)/50 yards. You can turn in a smaller area with vector thrust, however.