This guide is about the racing league series, Group H. It's seperated into 7 different classes.

• Gr.HMX-2
  
• Gr.HMX-4
  
• Gr.H1
  
• Gr.H2
  
• Gr.H3
  
• Gr.HDK
  
• Gr.HE

If you wish, make up a brand and give the vehicle a somewhat realistic name, alongside the original reason the vehicle was created. This isn't required, again, but it is heavily encouraged, just to keep the mind sharp and add inspiration.

Automatic transmissions are allowed.
All mods are allowed, and encouraged, as long as they do not tamper with the engines/wheels/transmissions.
Infinite resources are allowed.

Those of you that think you're being funny by interpreting the rules as allowing electrics are sorely mistaken and part of the reason I hate making rules. You are allotted ONLY the engines/motors provided and no more. Engine and motor are used INTERCHANGABLY in this document. Also, attempting to exploit a possible loophole in the rules, without being approved by me, will call for immediate disqualification of that vehicle from the class until issues are fixed. Those of you that cause this problem know who you are. This section applies to those of you who abuse bugs for performance gain.

Now, let's get on with it.

The following terms are frequently mentioned in the main vehicle classes - unless otherwise contradicted or specified, all mentions of these terms are to abide by the definitions listed here.

• Chassis - the primary component of a vehicle. It is supported by wheels and suspension articulation, and is where the seat, engine and fuel must be located. Bodywork is counted as part of the chassis, provided it is not mounted to a hinge.
  
• Wheelbase - length of the vehicle, measured from the raycast contact patches of the farthest-forward and farthest-backward wheels of the vehicle.
  
• Track width - width of the vehicle, measured from the outer edges (not necessarily raycast contact patch) of the outermost wheels of said vehicle.
  
• Hinge suspension or Spring suspension - in which a wheel hub is placed on the end of a hinge or hinges, such that the hinge assembly can articulate (IE it is not frozen in place via rod springs) and are sprung via spring blocks. With the exception of steering, no element of a vehicle's suspension may be controlled via logic.
  
• Minimum weight - wet weight, measured when the vehicle is first spawned with a full fuel tank. Note that detachers are not counted - vehicles are allowed to use detachers, but when detached while the parent vehicle has a full fuel tank, the vehicle must not be below the minimum weight for its class. Fuel tanks and batteries on detachers are strictly prohibited.
  
• Active aerodynamics - aerodynamic surfaces, IE wings, which are actuated, whether their articulation is voluntary (ie via hemi servos) or 'passive' (ie wing on a spring-loaded hinge mounted to the chassis, which compresses the spring as the vehicle's speed increases). Movement is restricted to increasing or decreasing AoA unless otherwise allowed.
  
• Hemi servos are allowed on wheels, provided they only control steering - IE, with no alteration to camber or caster angle at all.

After recent races, testing has proven that this kind of thing is a one-stop shop to make any badly driving car into something to be feared with one post.

Current list of known bugs:

• Castering drive wheels boosts the wheel's top speed without sacrificing torque. |Credit: Anna|

This section contains the rules for both HMX-2 and HMX-4 - a class for motorcycles, ATVs and other small "powersports"-type vehicles.
These were suggested by contributor Stinger.

• Allotted: 1 six-speed transmission and one "Small Wing" part placed vertically only. One rotation gyro for pitch control, with a maximum strength of the default 10000W, controlled by an infinite battery.
  
• Topspeed is max 110 mph.
  
• Max grip is 3.5 front and 4 side.
  
• Hide your ballasts and gyros with meshremover, if possible.
  
• AWD is strongly recommended.

• Minimum weight is 150kg.
  
• Engine: four [4] 2-strokes.
  
• Traditional, 2-wheeled bike styling
  
• Front suspension can be hub, but rear must be spring-based.
  
• Maximum length is 3 meters.
  
• You may use a PID-controlled roll gyro to keep the bike standing.

• Minimum weight is 250kg.
  
• Engine: one [1] nassin i4.
  
• Traditional, 4-wheeled ATV, or Snowmobile setup (possible with invisible wheels on the skids)
  
• All suspension must be spring-based.
  
• Maximum wheelbase is 3m, and max track width is 1.5m.

• Minimum Weight: 700kg.
  
• Vehicles must be laid out like a road-legal vehicle: with 4 wheels, one engine, one transmission, etc. Layout is up to the creator. (Yes, including Reliants and Slingshots. The "one" wheel in the front/rear must be two.)
  
• Vehicles are allotted ONE [1] six-speed transmission.
  
• They all must have a body. All the internal framing and such is not required.
  
• Vehicle wheelbase must be at or below 4 meters long. Vehicle track width must be at or below 3 meters.
  
• Servos of any kind are not allowed to move an upright vehicle except as specified in Common Terms, however they may be used to right the vehicle after falling over.
  
• Intentional weight-shift from a servo on a ballast is not allowed.
  
• Gyroscopes are not allowed in any way, shape, form, or fashion. No.
  

All types of conventional (IE road-legal) spring suspension are permitted. The wheels must have at least 5cm of articulation during driving conditions or they are disqualified.

• Wheels must be realistically scaled to their car's body.
  
• Rear-wheel steering is permitted for all Gr.H-series vehicles; the maximum rear-wheel steering arc must be five degrees in either direction.
  
• Friction values are capped at 3.5 forward and 4 sideways for all wheels. Minor detuning from this value (ie no more than a value of 0.1 in any friction value) is permitted for fine-tuning of vehicle performance.

• Powertrain: 1 Falcon 6.
  
• Must be 2WD.
  
• Topspeed of 150 MPH.
  
• Maximum surface area of 0.5m^2 horizontal wing surface.
  
• You can have .2m^2 vertical wing surface.
  
• No active aero.
  
• HUB SUSPENSION IS ALLOWED AS LONG AS IT IS LOW-TRAVEL!

• Powertrain: 1 Dutser v6.
  
• Must be AWD.
  
• Topspeed of 190 MPH.
  
• Maximum surface area of 2.0m^2 horizontal wing surface.
  
• You can have .2m^2 vertical wing surface.
  
• Rudders are allowed only if they are passive aero..
  
• Active Aero is allowed, BUT:
  
• >You are only allowed 4 seperate control surfaces. I do not care if they all move the same, each hemi+wing combo counts as one surface.
  
• >You are allowed 1.0m^2 of active surface area divided over the surfaces.
  
• >Each surface can only be moved a total of 15 degrees.

• Powertrain: 2x Dutser v6.
  
• Must be AWD.
  
• Topspeed of 225 MPH.
  
• Maximum surface area of 4.0m^2 horizontal wing surface.
  
• You can have .4m^2 vertical wing surface.
  
• Rudders are allowed only if they are passive aero..
  
• Active Aero is allowed, BUT:
  
• >You are only allowed 4 seperate control surfaces. I do not care if they all move the same, each hemi+wing combo counts as one surface.
  
• >You are allowed 2.0m^2 of active surface area divided over the surfaces.
  
• >Each surface can only be moved a total of 30 degrees.
  
• >Multiaxial wings are allowed, but individual axial movements cannot exceed 30 degrees when summed up. This also includes limiting or budgeting angle based on the situation.

Gr.HDK trucks are basically giant lorries/dakar trucks, maybe buses too.
General.

• Minimum Weight: 3000kg.
  
• Up to 8 wheels maximum.
  
• Powertrain: TWO [2] D22 Twister diesel motors.
  
• You are allotted ONE [1] 13-speed transmission and ONE [1] six-speed [with only 2 usable gears + 1 dummy gear for "clutch"] for different gear ranges.
  
• They all must have a body. All the internal framing and such is not required.
  
• Vehicles must have a top-speed of 150 mph.
  
• Vehicle track width must be at or below 3 meters.
  
• Wheel width must not exceed 1.
  
• Servos of any kind are not allowed to move the vehicle (aside from the case in Wheel-Specific), however they may be used to right the vehicle after falling over.
  
• Intentional weight-shift from a servo on a ballast is not allowed.
  
• Gyroscopes are not allowed in any way, shape, form, or fashion. No.
  
• Maximum Aero should not go past 5m^2 of surface.
  
• Active Aero is allowed. You are only allotted 4 control surfaces and cannot have more than 2.5m^2 of active aero.

Suspension/wheels.
All types of conventional (IE road-legal) spring suspension are allowed as long as they are not locked or controlled by logic. They have to have at least 15cm of articulation during driving conditions or they are not allowed.
Anti-Roll/swaybars are allowed aswell.

• Wheels must be realistically scaled to their car's body.
  
• All-wheel steering is permitted, however, rear pairs of wheels may possess steering, if their steering authority is limited to 5 degrees either direction of steering.
  
• Friction values are capped at 3.5 forward and 4 sideways for all wheels. Minor detuning from this value (ie no more than a value of 0.1 in any friction value) is permitted for fine-tuning of vehicle performance.

General.

• Minimum Weight: 500kg.
  
• 4 wheels maximum.
  
• Powertrain: ONE [1] E-Power motor.
  
• You are allotted ONE [1] six-speed transmission.
  
• They all must have a body. All the internal framing and such is not required.
  
• Vehicles must have a top-speed of 300 mph.
  
• Vehicle track width must be at or below 4 meters.
  
• Wheel width must not exceed 1.
  
• Servos of any kind are not allowed to move the vehicle (aside from steering), however they may be used to right the vehicle after falling over.
  
• Intentional weight-shift from a servo on a ballast is not allowed.
  
• Gyroscopes are not allowed in any way, shape, form, or fashion. No.
  

Suspension/wheels.
Please, use hub suspension for this. I don't want you to die. But, if you want a challenge, you may use spring.

• Wheels must be realistically scaled to their car's body..
  
• Friction values are capped at 5.5 forward and 6 sideways for all wheels. Minor detuning from this value (ie no more than a value of 0.1 in any friction value) is permitted for fine-tuning of vehicle performance.

Aerodynamics.

• Maximum surface area of 4.0m^2 horizontal wing surface.
  
• You can have .4m^2 vertical wing surface.
  
• Rudders are allowed only if they are passive aero..
  
• Active Aero is allowed, BUT:
  
• >You are only allowed 4 seperate control surfaces. I do not care if they all move the same, each hemi+wing combo counts as one surface.
  
• >All aero on the vehicle, except the rudder, can be active
  
• >Each surface can only be moved a total of 45 degrees.
  
• >Multiaxial wings are allowed, but individual axial movements cannot exceed 30 degrees when summed up. This also includes limiting or budgeting angle based on the situation.

These classes do sound like they're just as strict as the late HRL, but this whole guide is mostly about vehicular design within rules, rather than the actual competition.

Don't take losing too seriously. We're all here fighting the builder together.


We are beginning to go public with Velocity Valley! Velocity Valley is a rolling competition for these rules, hosted by me, TylissiusR! Click here to join our discord![discord.gg]

Credit to Llama for the old logo.
Credit to Stinger for inspiration, Gr.HMX setup, and Common Terms sections.

Signed, TylissusR.