# Lernkarten

Karten 42 Karten 4 Lernende English Universität 22.02.2020 / 05.06.2020 Keine Angabe
0 Exakte Antworten 38 Text Antworten 4 Multiple Choice Antworten

From the Breguet endurance formula follows that in order to maximize endurance we have to:

• maximize propeller efficiency $$\eta_p$$
• minimize specific fuel consumption SFC (engine efficiency)
• fly at the maximum $$c_l^{3/2}/c_d$$ (aerodynamic efficiency)
• cater as much fuel as possible (structural efficiency)

Define endurance:

Endurance is the amount of time that an aeroplane can stay airborne on a load of fuel.

Endurance of a propeller-driven aeroplane is altitude dependent: Yes No

The endurance of a jet aeroplane is dependent of altitude: Yes No

To achieve maximum endurance for a jet aeroplane we have to:

• Fly at maximum L/D
• Have the lowest specific fuel consumption TSFC
• Carry a lot of fuel

Explain the concept of Energy Heigt $$H_e$$:

The energy of a flying plane can be split into kinetic and potential energy.
The total energy can be transformed from one form to another. If the plane does so, it travels along a socalled Constant Energy Height. (As long as no energy is lost, so only theoretical!)

How can an airplane change its energy height?

By applying excess power.

The time rate of change of Energy Height is equal to the Specific Excess Power (SEP)

How do the speeds for best (maximum) ROC and minimum power in level flight compare?

(based on the assumption that propeller efficiency and available power are both independent of speed) V_best_roc > V_min_power V_best_roc = V_min_power V_best_roc < V_min_power