# Jumping... and falling

### Text and Photos by John M. Hurtt New Jumping Rules for Car Wars!

Editor's Note: These are not official changes to the Car Wars rules. They're merely a variant for people who want a somewhat simpler (though admittedly less accurate) method of determining jump distances and heights.

## INTRODUCTION

What?! Another set of jumping rules?

Well, yes. The rules by Ben Ellinger and Ken Scott (printed in Uncle Albert's Catalog From Hell) definitely do the job when it comes to precisely determining where cars are in mid-air, but they have a tendency to stop games dead in their tracks if several cars take flight -- unless someone in the group is really fast with a calculator, of course.

I'll admit it; I'm math-illiterate for the most part. Without a calculator my brain seizes up. Quite frankly, I'm terrified to try a jump now, simply because I don't want to irritate the rest of the game group while I wrestle 15 minutes with the rate-of-climb formula and the phase chart.

Another problem is that the new jumping rules do not yield a consistent length of jump as you increase speed. For example: from a 30° ramp, a 50-mph jump yields a distance of 10.5". A 55-mph jump yields a distance of 11.5". But a 60-mph jump will send the vehicle flying 15", while a 65-mph jump only bumps the distance up to 16.5". Obviously, this is not a steady progression.

I wanted something akin to the old jumping rules in relative ease of play, but also something accurate enough to show where the vehicle was in relation to the ground at any phase (no pun intended) of the jump. I came up with these rules after realizing that the old jumping rules would work if the results were varied by the takeoff angle. By determining where the car would be at its highest point, it is much easier to determine the vehicle's height at other points in the jump.

Note that these rules are only for jumping from standard arena ramps (multiples of 15°). The new falling rules still have their place in this system, but they're only used after a vehicle has completed the "normal" part of its jump. That is, once a vehicle returns to the elevation it had when it left the ramp, if there isn't another ramp there to receive it, the regular falling rules go into effect. This will happen when an off-road vehicle is jumping off a cliff or a hill, or when an arena jumper has miscalculated badly.

These rules will also make it much easier to figure out mid-air targeting or colliding situations, and will therefore encourage duellists to slam the pedal down and jump for it!

### DETERMINING JUMP DISTANCE

15° and 60° ramp jumps: Subtract 20 mph from the takeoff speed, and divide what remains by 10 to get the distance traveled in inches. For example, a 50-mph jump will carry you 3 inches (50 mph - 20 mph = 30 mph, then 30 mph / 10 = 3 inches).

30° ramp jumps: As above, but multiply the results by 2. In the example above, a 50-mph jump would travel 6 inches.

45° ramp jumps: As above, but multiply the results by 2.5. In the example above, the 50-mph jump would net 7-1/2".

75° ramp jumps: As above, but divide the results by 2. Our 50-mph jump only moves us 1-1/2".

### DETERMINING ALTITUDE

To determine the height of a vehicle at any given point during a jump, first find the vehicle's height at apogee (the high point of the jump). This is equal to either one-fourth, one-half or three-fourths of the total jump distance (figured from above) depending on the take-off angle of the jump ramp.

15°and 30° ramps produce an apogee height of one-fourth the jump distance.

45° ramps give an apogee height of half the jump distance.

60° ramps yield an apogee height of three-fourths the jump distance.

75° ramps give an apogee height equal to the jump distance.

Example: A car jumping off a 30° ramp at 60 mph will jump for a total of 8". One-fourth of this distance is 2", so the car has an apogee height of 2". Add to this the launch ramp height of 2", to give a total altitude of 4" from the ground the ramp is sitting on.

Now check the current position of the car in relation to the apogee and the nearest ramp. Divide the distance between the center point of the vehicle and the nearest ramp into the total distance between the apogee point and the ramp. The result is the percentage of the total jump height the vehicle currently has. Remember, that percentage is just of the jump height, not the total elevation from the ground.

To continue the example above, let's say the car has traveled 5" of its 8" jump. The distance from the car to the nearest ramp (in this case, the landing ramp) is 3". The distance from the apogee to that same ramp is 4". By dividing, we get 75%. Multiply that by the 2" apogee, and you get a current jump height of 1-1/2". Add that to the 2" the ramp extends above the ground, and you get a total altitude of 3-1/2".

### DETERMINING ROTATION IN FLIGHT

A vehicle begins a jump with an upward tilt equal to the inclination of the launch ramp. It will then rotate by 15 degrees (front downwards) a number of times in flight. If jumping to a matching opposing ramp (at the correct speed for the distance), then the rotations will be just enough to have the car pointing down at an angle equal to its takeoff angle when it lands.

The steeper the takeoff angle, the more rotations a vehicle will make as it jumps. These rotations are spaced evenly along the flight path of the car.

The last rotation always takes place during the last inch of the jump (as the vehicle is landing, if there is a matching ramp).

15° jump: 2 rotations

30° jump: 4 rotations

45° jump: 6 rotations

60° jump: 8 rotations

75° jump: 10 rotations

Note that a short, high-angle jump may result in the vehicle rotating several times in one phase. A car automatically rotates forward, but a cycle may chose whether to rotate forward, backward or not at all. This choice must be made at takeoff and cannot be changed during flight.

### COLLISION DAMAGE AND FALLING AT THE END OF A JUMP

When landing from a jump using the above rules, assess hazards and damage either by:
(A) using the jumping and falling rules in the Car Wars Compendium or
(B) by using the new falling rules in Uncle Albert's Catalog From Hell.
If using the new falling rules, the downward velocity of the vehicle (in inches per phase) at the end of a jump is equal to its speed plus the original jump-ramp angle (if the vehicle drove off a cliff or building top this will be 0), divided by 150 and rounded down to the nearest 1/4".

Example: A car completing a 60-mph jump from a 30° ramp lands on a matching ramp. The vehicle's downward velocity is 30 (degrees) plus 60 (mph) divided by 150, which equals 0.60, which is rounded down to 1/2". So the vehicle suffers a "collision" at 20 mph, minus 10 mph because it landed on its wheels (and minus the remaining 10 mph if it has HD shocks), the damage of which, if any, is applied randomly among the tires.

If there is no landing surface at the end of a jump using the rules in the sections above, then the new falling rules in UACFH must take over, using the above formula to figure the vehicle's initial downward velocity.

Overall example: The car in the examples above, jumping off a 30° ramp at 60 mph, will travel a total of 8", will have an apogee height of 2", and will rotate 15 degrees a total of 4 times. The final rotation will be in the same phase that the car moves its eighth inch in flight. The other 3 rotations will be evenly spaced along the 8" jump (i.e., at 2, 4, and 6 inches along the flight path). If there is a matching 30° ramp at the end of the jump, then the vehicle lands normally as per the Compendium rules. If there is no ramp, then the vehicle begins to fall and rotate according to the falling rules in Uncle Albert's Catalog From Hell.

### MID-AIR COLLISION CLARIFICATIONS AND OPTIONAL RULES

If two vehicles are on a collision course in mid-air, use the following guidelines and optional rules to adjudicate the results of the collision.

Altitude
At or just before the moment of impact, figure out the precise altitude of both vehicles using the rules above. Remember that the center point of the vehicle is at that altitude -- if the vehicle is tilted either forward or backward, then the front (or rear) of the car will be 1/8" higher (or lower) than the center for every 15° angle of tilt beyond the first 15 degrees (up to a maximum difference of 1/2" for cars). Thus, a 15° tilt means the vehicle's front and rear ends are effectively still the same height as the center of the car, but a 45° angle means the front and rear ends are 1/4" higher or lower than the center of the body.

Vehicle Heights
Next use the vehicle height to determine how it affects the type of collision. (The following is repeated from the "Jumping and Falling Rules" in Uncle Albert's Catalog From Hell.

Motorcycles, trikes, sub-compacts and compacts are considered to be 1/4" tall.

Mid-sized, sedans, luxuries and station wagons are 3/8" tall.

Pickups, campers and vans are 1/2" tall.

Ten-wheelers are 3/4" tall.

18-wheelers are a full inch tall.

Ramplates on all cars (i.e., vehicles found on pp. 50-55 of the Compendium, or pp. 155-160 of Uncle Albert's Catalog) and reversed trikes are considered to be 1/4" tall. Ramplates on all oversized vehicles are considered to be 1/2" tall. Note that in some cases it will be possible for a ramplate equipped vehicle to collide with an airborne vehicle and not gain the benefits of the ramplate, because the airborne vehicle, while not high enough to clear the vehicle, is high enough to clear the ramplate.

Note that ramplates cover the entire (non-windshield) front of the vehicle. Thus, the "front" of a car (or reversed trike) is 1/4" tall while the rest of the vehicle, if larger than a compact, is higher. And the "front" of any oversized vehicle is 1/2" tall. This is important for use in modifying the collision type (see below).

Collision Types
Next determine the standard type of collision (i.e. Head-on, Rear-end, T-bone or Sideswipe). Modify these collisions as follows.

HEAD-ON: If the vehicle "front" ends collide (no more than 1/4" difference between the height of the front ends of both cars, or 1/2" if an oversized vehicle is involved), then the collision is resolved normally.

Both vehicles are now "falling." Figure their initial downward velocity using the new speeds of the vehicles (probably zero for at least one of them, most likely both of them). Any remaining horizontal movement is carried out normally while falling.

If the vehicle front ends are separated by more than 1/4" of height (1/2" for oversized vehicles), then the collision becomes a Sideswipe, with the higher vehicle's bottom armor sideswiping the lower vehicle's top armor. The higher vehicle is raised 1/2" by the sideswipe, while the lower vehicle drops 1/2" from the collision. Otherwise the two vehicles continue their original jumps unaffected.

REAR-END: Same as Head-on, except that the leading vehicle continues its jump (adding on any speed change, but the vehicle will still start "falling" after it reaches its original jump distance), while the trailing vehicle begins to fall immediately.

T-BONE: If the vehicles collide with more than a 1/4" difference in height, then again, one vehicle's bottom armor sideswipes the other vehicle's top armor. However, if one car squarely impacts the side of the other, first resolve the collision normally, then do the following:

V1 (the vehicle that is committing the T-bone) compares its new speed versus the speed needed to complete the jump it just made and the amount of distance traversed. If V1 is still going fast enough to go farther than it already has, then it completes that amount of jump normally (rotations are now every three phases automatically), and then begins to "fall." If V1's speed is not fast enough to go any farther as a "jump" then the vehicle begins to fall immediately.

Example: A vehicle launches itself from a 30° ramp at 60 mph for a total of an 8" jump. One and a half inches into the jump it T-bones another vehicle and has its speed is reduced to 30 mph. At 30 mph the vehicle now has a total jump of 2". Since the car has already jumped 1-1/2", then it can only jump for 1/2" more before it begins falling.

V2 (the vehicle getting T-boned) conforms to V1's movement as normal and may be knocked off course as well. There is a 1-in-6 chance that V2 will be knocked off course, +1 for every 1,000 lbs. of vehicle weight that V1 has over V2 (-1 per 1,000 lbs. under), and/or +1 or -1 for every 20 mph that V1 is traveling faster or slower than V2 (at the time of impact). If V2 is deflected off course, roll 1 die. On a 1-3, it is deflected 15°; on a 4-6, it is deflected 30°. V2's speed is unaffected whatever the result and it finishes its jump, including rotations, before beginning to fall.

SIDESWIPE: The collision is resolved normally except that there is a 1-in-6 chance that one or both vehicles may be knocked off course by the collision. Roll 1d6 for both vehicles. If one or both cars are knocked off course, it will be at a 15° angle away from the collision. Both vehicles finish their jumps normally with no changes in speed, altitude or rotations.

In all cases, accumulated hazards from collisions are added to the total difficulty of landing for handling purposes.

### STEP-BY-STEP

At first, you only need to figure out the distance a vehicle will jump when it leaves an arena jump ramp. You figure rotations only if the vehicle is not traveling the correct speed to land precisely on a matching opposing ramp. And you don't need to figure current height from the apogee unless there is the possibility of a mid-air collision or someone shoots at the jumping vehicle. Finally, you only need to calculate the downward velocity if you are assessing landing damage using the new jumping and falling rules from UACFH. Thus, you can eliminate time-consuming calculations for many jumps during an arena combat, and considerably shorten the calculations for off-road duelling, while still avoiding arguments over where a jumping vehicle precisely is.

Enjoy!

## Sidebars

Jump Jets | Rocket Boosters

# JUMP JETS

When Jump Jets are fired, they affect a car the same way Rocket Boosters do, only in a vertical direction. The only difference is that Jump Jets are counteracting the pull of gravity (much in the same way that a jump ramp helps a vehicle to temporarily thwart it). Therefore, just like a vehicle jumping off a ramp, the first 20 mph of acceleration from a continous burn of Jump Jet (whether in one turn or several) is used just defeating the vehicle's weight. Any additional burn will begin to lift the vehicle vertically at the same rate at which Rocket Boosters would accelerate that weight of vehicle.

Once a Jump Jet burn is complete the vehicle will either:

(A) complete its flight (if the Jump Jets were fired during mid-jump) or,

(B) begin to fall according to the "Altitude Loss" rules in Uncle Albert's Catalog From Hell.

Example: A 6,600-lb. Luxury, equipped with a single Jump Jet tube with 200 lbs. of fuel (\$1,000, 2 DP, 2 spaces) preset to burn 100 lbs. of fuel per turn, activates the Jump Jet while traveling along the road on phase 1 of turn 1. One hundred pounds of fuel will generate 15 mph of acceleration for a 6,600 lb. vehicle, so during turn 1 the vehicle will continue down the road at whatever horizontal speed it is traveling as it builds up vertical thrust. On phase 1 of turn 2 the Jump Jet burns its remaining 100 lbs. of fuel generating another 15 mph of acceleration. Since this is a continuous burn from the previous turn, the vehicle only needs another 5 mph of acceleration to overcome gravity. The remaining 10 mph of acceleration will lift the vehicle immediately to a height of 1" at which altitude it will remain until phase 1 of turn 3 (another simplification, but it plays easily). On Phase 1 of turn 3 the vehicle will immediately begin to fall at a rate of 1/4" per phase until phase 4, when it will accelerate its fall to 1/2" per phase (of course, in this example it should land during this same phase, unless the vehicle drove off a cliff or something).

Note that Jump Jets prevent rotation while they are firing, but the vehicle will begin to rotate 3 phases after the tube(s) run out of fuel.

Example: The same 6,600-lb. Luxury, equipped with the same Jump Jet, fires the tube while in the middle of a jump. If the tube is ignited before or at the point of apogee, then the 20 mph penalty of countering gravity is ignored (the jump ramp took care of that already) and the vehicle immediately adds 1-1/2" (for the jets' 15-mph acceleration) to its current height (figured from the original apogee height), continues its original jump, and adds another 1-1/2" to its height on the same phase of the following turn. No rotations are performed while the Jump Jet is firing and any rotations that were scheduled to take place during those phases/turns are lost. The vehicle now completes its originally calculated jump distance, performing any remaining rotations. If the vehicle does not land at this point, then it begins to fall according to the new falling rules.

If the Jump Jets are fired after apogee, then the 20 mph penalty applies. This means the Jump Jet must provide at least 20 mph of thrust (in one turn or several) before the vehicle begins to gain altitude with the remaining thrust (as described above). Note that the vehicle will stop losing altitude while the Jump Jet is firing until the 20 mph penalty is paid. Again, no rotations are performed while the Jump Jet is firing and any rotations that were scheduled to take place during those phases/turns are lost. When the Jump Jet stops firing the vehicle completes any of its remaining original jump distance normally.

Note that firing Jump Jets may take a vehicle higher than the apogee height originally determined. If this occurs, treat the accumulated inches over the original apogee as mph (for example, a height of 1-1/4" over apogee would be 12.5 mph), and add this to the original speed of the vehicle for determining initial downward velocity once the vehicle reaches the end of its original jump distance.

Example: A car fires a Jump Jet in the middle of a jump off a 30° ramp while traveling 60 mph. The Jump Jet is fired at apogee and has a total thrust of 25 mph, which adds a total of 2-1/2 inches to the vehicle's apogee. (If the Jump Jet burns in one turn, then the vehicle immediately ascends the 2-1/2". If the Jump Jet burns over several turns, then the car will rise the appropriate height every turn on the same phase as the Jump Jet(s) were triggered). When the vehicle reaches the end of its original jump distance it will be two and a half inches higher than the matching ramp (if there is one) and will begin to fall, adding 25 mph to its original speed (for the extra 2-1/2") for determining the initial downward velocity as follows: 30 (degrees of ramp) plus 60 mph (original speed) plus 25 mph (extra speed) divided by 150 equals .76, which rounds down to .75 or 3/4" of initial downward velocity.

# ROCKET BOOSTERS

Rocket Boosters will, of course, simply affect the total jump distance of the vehicle if fired before or during the first half of the jump (up to and including the phase the vehicle reaches its apogee height). For each 10 mph of acceleration gained through the RBs, the vehicle will fly an additional inch before reaching its original take-off altitude. When RBs are fired, calculate the new distance that the vehicle will fly and immediately figure the new apogee height the vehicle will reach. Any rotations already completed stand, and remaining rotations are evenly spaced along the remaining flight path with the last one occuring during the last phase of flight as usual. (This is a gross simplification of the physics, but it does facilitate quick play). The vehicle will also accelerate normally for Rocket Boosters.

If Rocket Boosters are fired after a vehicle has passed its apogee, then there is no increase in the amount of jump distance to the opposing ramp (if any), but the vehicle will travel the extra inches of flight using the above rules (including stretching the distance between rotations) before reverting to the new falling rules. This means that a vehicle firing RBs after apogee will likely land rear wheels first on a landing ramp, adding a D1 hazard to the landing for every 15° difference in the pitch of the vehicle and the ramp, according to the rules in UACFH.

If Rocket Boosters are fired when the vehicle is at a pitch of greater than 45°, then they will act as jump jets (see below), except that RBs are not (usually) gyrostabilized like jump jets, and therefore the vehicle will still rotate.

Article publication date: February 1, 1994