Enum Inflation 

#[non_exhaustive]
pub enum Inflation {
    Instant,
    FillingTime {
        time_s: f64,
        exponent: f64,
    },
    FillConstant {
        constant: f64,
        exponent: f64,
    },
}

How a device’s drag area grows once it is deployed.

Knacke’s measurements (Figure 5-40, printed page 5-47) overshoot the steady drag area by 10 to 80% near the end of filling. These laws don’t: they rise to the steady value and stay there.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Instant

The full drag area from the moment the device deploys.

FillingTime

(C_D S)(t) = (C_D S)₀ (t/t_f)^j over a filling time t_f fixed in advance.

Fields

time_s: f64

The filling time t_f, s.

exponent: f64

The growth exponent j (Pflanz: 1 for ribbon and ringslot, 2 for solid cloth).

FillConstant

The same growth law with Knacke’s filling time t_f = n D₀/v (printed page 5-43), where v is the airspeed at deployment and n the canopy fill constant. Needs a device with a nominal diameter.

Knacke states this linear form “gives satisfactory results in the medium-velocity range of about 150 to 500 ft/s” (45.7 to 152.4 m/s, printed page 5-44). A hobby main opening at 20 to 30 m/s is below that range, and his alternative there (t_f = n D₀/v^0.85, n = 4.0 for solid flat circular canopies) is dimensional, so it cannot be used in SI as printed. Inflation::FILL_CONSTANT_RANGE_M_S holds the range, and docs/physics/recovery.md says what using it outside costs.

Fields

constant: f64

The fill constant n (Table 5-6).

exponent: f64

The growth exponent j.

Implementations

impl Inflation

pub const FILL_CONSTANT_RANGE_M_S: (f64, f64)

The airspeeds at line stretch where Knacke’s linear filling time t_f = n D₀/v is stated to hold, m/s (150 to 500 ft/s, printed page 5-44).

pub const fn knacke(kind: CanopyType) -> Option<Self>

Knacke’s filling time and growth exponent for kind, where his tables print both.

Trait Implementations

impl Clone for Inflation

fn clone(&self) -> Inflation

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Inflation

impl Debug for Inflation

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Inflation

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Inflation

fn eq(&self, other: &Inflation) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Inflation

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Inflation