# P2 base, wheel-fan and electromagnetic hydraulic architecture

The user's wheel idea is retained: the **wheel assemblies turn outward into fan
orientation** to press the body down, rather than lift it. The deployed concept
pose is in `output/wheel-fan-mode.png` and `cad/wheel-fan-poses.json`.
It is a kinematic proposal, not a qualified road transition or rotating-blade test.

## Mechanical arrangement

The tyre carrier tilts on a dedicated module hinge. A purpose-designed impeller
inside it has its own drive/bearings: ordinary road-wheel rotation is not a fan
performance specification. The bench concept uses a 54 mm wheel outside diameter,
36 mm active impeller diameter and 14 mm hub. These are layout parameters, not
qualified rotor dimensions, blade angles or operating speeds.

In the fully horizontal fan pose, normal rolling tyre contact is unavailable.
Instrumented base pads then carry the body load and fan reaction. This changes
both braking and directional control; it cannot be evaluated as tyre ABS alone.
The illustrated outboard pose widens the 1:10 module envelope to about 260 mm.
Clearance, collision avoidance, ground intake restriction and the deployment load
case require dedicated physical/CAD/structural tests.

Air leaving upward produces a downward reaction on the module. The complete
vehicle force must also include pressure on the body and underfloor. Do not add
an isolated rotor thrust to a whole-body force result that already includes it.
Ground suction/duct effects can change installed performance; the present isolated
fan resource screen does not model those interactions.

## Independent hydraulics driven electromagnetically

The proposed supply is an electromagnetic motor/pump or electromagnetic piston
driving hydraulic pressure, with an optional metered accumulator. It is independent
of wheel-brake hydraulic pressure. An electrical store/DC bus supplies the work.
Permanent magnets alone are not counted as an energy source.

Cylinders move the wheel modules and control pad load/height. The simple work
screen in `output/resource-screens.json` uses direct cylinder force, bore and stroke
targets. Actual hinges need torque/inertia/gyroscopic/locking/structural analysis;
those loads are not inferred from that direct-force screen. No pump, seal or
pressure component is qualified by the calculation.

For a bench demonstration, first support the article independently of fan thrust.
Measure wheel angle, cylinder position/pressure, pad normal load and fan electrical
input. Establish fan-axis direction and rotor clearance before spin tests. No
vehicle-speed deployment procedure or public-road controller is supplied.

## Three operating modes and one resource ledger

| Mode | Flow machinery | Energy and control accounting |
|---|---|---|
| Charging | Intake flow drives generator torque | Include the turbine reaction and the change in whole-body drag. Recovered DC power requires a measured generator map. |
| Speeding | Electrical motor drives the duct fan | Record supplied power, rotor reaction and complete body force. A powered fan is not unpriced extra thrust. |
| Braking | Turbine drag/recovery where useful; wheel-fans and controlled base contact | Count powered downforce and deployment energy; compare usable axial force and yaw/path control with measured pad/tyre behavior. |

A rotor cannot receive both generator-output and motor-thrust credits for the
same operation without accounting for its actual torque/power direction. Charging
and powered duties are switched explicitly. Wheel-fans and hydraulics draw from
finite reserves; no claim is made that the small charging test powers them all.

## Materials for maximum usable base grip

Use new tread-grade elastomer candidates identified by formulation/batch, including
condition-specific silica-filled compounds from a specialist supplier. Include dry,
wet and cold/ice candidates; record hardness, thermal behavior, wear and backing.
Material price, a high hardness number or a carbon/ceramic label does not establish
grip on an actual road. The load-bearing pad carrier is a separately engineered part.

The empty `experiment/friction-records.csv` is for actual tests. For each candidate,
use the same substrate, surface preparation, normal pressure, slip speed,
temperature, wet/ice condition and pad geometry. Randomize run order and repeat
independently. Measure tangential force and normal load, and calculate their ratio
with calibration uncertainty. Retain raw signals and wear observations.

A flat coupon is not a complete tyre contact patch. Do not import its coefficient
directly into a vehicle stopping-distance claim. Do not combine separate maximum
longitudinal and lateral friction values as simultaneously available steering.

No coefficient is assigned in the resource screen. It reports only an inverse
threshold: with fully unloaded tyres and constant-friction pads carrying weight
plus added downforce, matching the original axial tyre capacity requires
`mu_pad/mu_tyre >= 1/(1+Fdown/weight)`. This conditional load algebra excludes
load sensitivity, contact transients, wear, ice, steering and road geometry.

## Tests needed before integration

1. Static wheel-pose, hose/wire routing, module-envelope and pad-load tests.
2. Electromagnetic hydraulic force/torque, energy, timing and lock/hold tests.
3. Contained impeller thrust/flow/power tests in the installed geometry.
4. Pad-compound friction/wear maps on the intended surfaces and conditions.
5. A coupled dynamics model using those measurements for load transfer, yaw and path.

The body-flow CFD in this package has fixed wheels and no ground. It does not
perform these wheel/pad tests. The full plan's thermal, phase-change, pulse-store
and ECRS branches remain separate work packages with their original evidence gates.