How do planes turn against the wind
Flying is very often a great mental effort. In such situations, rules of thumb can be very useful: they save time, are based on empirical values and almost always fit.
Everything takes longer than is generally assumed.
This cardinal rule applies to the entire conduct of a flight. Experienced pilots use them specifically when estimating their expected arrival and handling times, when weather improvements have been announced, when determining their take-off and landing routes and when optimistic shipyard times are set.
To calculate the speed over the ground, headwinds should always be set at 150% and tailwinds at only 50% of the actual value.
If the wind speed is to be divided by 4, it is better to take half. On a cross-country flight, headwind has a greater influence on the flight time than tailwind, because the duration of the influence is shortened by tailwind. Headwind and tailwind have no different effects when taxiing and approaching.
A tank stopover extends the block time by around 45 minutes, because it almost always includes:
- at least one phone call
- Paying the fuel bill
- Oil check
- "Freshen up" the pilot and passengers.
Another 10 minutes will surely go by if a bad weather front approaches and you want to start before that ...
A refueling stop costs at least half an hour's fuel consumption.
Landing and climbing back to cruising altitude cause an additional fuel consumption of 5 to 8 US gallons. In the case of turbochargers, the value increases by 50%, in the case of light twin engines, it is doubled.
Tail-heavy planes are faster.
If the center of gravity moves backwards, i.e. closer to the center of lift, the aircraft is better balanced. At the same time, the negative lift is increased and the aerodynamic drag of the horizontal stabilizer is reduced. The stall speed decreases and heavy aircraft landing becomes easier because the control pressure on the elevator decreases. However, the Center of Gravity must remain in the specified area.
The most economical cruising altitude for aircraft with normal piston engines with a power division of 75% is between 6000 and 8000 ft MSL.
This height should be maintained in order to achieve a constant performance of 75% and the highest possible airspeed for a given fuel consumption. When the power is reduced, the optimum level increases. In spite of everything, for the profitability of a flight it is essential to include: high altitude wind, climb time and fuel consumption during the climb.
Turbochargers are most powerful over 20,000 ft.
In some flight manuals for turbochargers, lower operating altitudes are specified for reasons of engine cooling.
A climb of more than 10 minutes per cruise hour is uneconomical.
In individual cases, a climb to the optimal cruising altitude can be too expensive; namely when the fuel savings above are canceled out by increased fuel consumption in the climb. An exception is climbing with a strong tailwind.
Estimation of fuel consumption
With the usual piston engines in our E-Class aircraft, the fuel consumption can be estimated immediately using the power setting: Fuel consumption = HP x power setting [in%] x specific fuel consumption for the specific fuel consumption factor, the following values are used: Unit with optimal leasing with turbocharger Engines pounds per hour 0.43 0.48 gallons per hour 0.0717 0.0800 liters per hour 0.271 0.303
Example: a) a 200 HP motor therefore consumes approx. 55.9 pounds / h with a power setting of 65% (200 x 0.65 x 0.43 = 55.9) b) a 160 HP motor accordingly consumes with a power setting of 75% approx. 32.5 liters / h (160 x 0.75 x 0.271 = 32.5)
For the fuel consumption when climbing, an additional 2 liters / h per cylinder are calculated.
With a 4-cylinder engine, 8 liters / h are added to the calculated fuel consumption for the cruise. A few liters (at least 5..10) should also be taken into account for rolling and starting!
An increase in power causes a double increase in fuel consumption in relation to the increase in speed.
An average light single engine consumes 13% more petrol with a power setting of 75%, but is only 6% faster than with a power setting of 65%. At 55% power, 25% less fuel is required, but the speed is only 12% slower than at a setting of 75%.
The true airspeed changes by around 1% for every 1000ft of altitude difference.
This relation is important for the determination of the flight altitude in strong headwinds. An aircraft with 150 kts TAS at 2000 ft has a TAS of 159 kts at 8000ft. Caution: Turbulence reduces the TAS, so choose a low-turbulence altitude if possible.
To calculate the density height, every 1000ft is added to the pressure height for every 2 ° C higher temperature compared to the standard temperature.
More precisely: based on the standard pressure (1013 hPa) and the current altitude, the pressure altitude is first calculated from the QNH (current altitude +/- 30ft per hPa pressure difference between QNH and standard pressure), and this is then corrected by 120 ft per Kelvin temperature difference compared to the standard temperature at this altitude (the standard temperature at sea level is 15 ° C, it drops by 2 ° C for every 1000ft increase in altitude).
The take-off distance increases (compared to the value in MSL) by at least 10% for every 1000 ft higher density altitude.
In addition, it is shortened by 1% for every 1kt headwind, or it is lengthened by 5% for every 1kt tailwind. Note: the influence of a tail wind is five times more noticeable than that of a head wind.
For safety reasons, the calculated take-off taxi distance should be doubled.
Fix half of the runway. If your plane has not yet taken off there, take-off is unsafe. Most aircraft have to be braked faster than accelerated, so that there is still enough runway available for an aborted take-off.
The climb gradient can be calculated by dividing the rate of climb by the NM covered per minute.
The increased altitude in ft / NM is particularly important in mountainous terrain or for overcoming obstacles. Example: 100 kts GS corresponds to 1.666 NM / min. 600ft / min climb rate divided by 1,666 NM / min gives 360ft climb per NM. If a mountain with a height of 5000ft is only 10 NM away, it is better to draw circles while climbing.
For the calculated flight time between two checkpoints during a climb, half a minute is added to the calculated cruise time for every 1000 ft of climb.
Example: Climb to 6000ft, GS 120 kts, distance from the first checkpoint 40 NM. The calculated flight time there is 23 minutes.
The maneuver speed is roughly equal to the square root of the safe load multiple multiplied by the stall speed.
Example: The safe load multiple of the normal aircraft category is 3.8 g (4.4 g for the commercial aircraft category). 3.8 = 1.95, i.e. approx. = 2; Va = Vs x 2.
The maximum flight time is achieved by observing Vy (speed with the best rate of climb).
At this speed, the relationship between lift and drag is also optimized. You need the least amount of power to maintain straight flight. Vy creates leeway in the event of a loss of orientation, and is recommended in IFR training, in holdings or when approaching delays caused by the ATC. Attention: observe the motor temperature!
The maximum range is achieved with Vy + 25%.
This speed usually corresponds to a power setting of 45%. Some types of aircraft may only save a few miles, but they could make the difference!
At a distance of 60 NM from the VOR station, 1 ° course deviation corresponds to a course deviation of 1 NM.
If the VOR needle moves completely, this means a deviation of 10 °. If the needle has emigrated halfway and you are 60 NM from the station, the course deviation to the left or right is 5 NM.
The performance data of an aircraft are reduced by half the percentage by which the total weight is undercut.
Stall, climb and approach speeds are sensitive to flight weight. If the flight weight is reduced by 10%, these speeds decrease by 5%.
To calculate estimates on the route at a GS of 150 kts, multiply the distance by 4 and simply leave out the last digit.
Example: Distance 50 NM. 50 NM x 4 = 200 NM or 20 minutes. With a GS of 100 kts, multiply by 6, with 120 kts, divide by 2, with 180 kts, divide by 3. 120 kt = 2 NM / min
The descent should be initiated for every 1000 ft loss of altitude at a distance of 5 NM from the target.
Example: With a loss of altitude of 8000 ft, the descent begins 40 NM in front of the runway. The rate of descent depends on the GS. It is 300 ft / min at 90 kts, 400 ft / min at 120 kts, 500 ft / min at 150 kts, 600 ft / min at 180 kts, 700 ft / min at 210 kts. The rate of descent varies by 100 ft / min for every 30 kts change in speed. (120kt = 222 km / h)
Cloud bases and visibility worsen in the evening or immediately after sunrise.
Elevation winds in a front area increase.
If the wind direction behind a cold front is more or less perpendicular to the front direction, a stationary cold front occurs, which moves on as a warning front after a few days. Beware of north-east winds behind a cold front!
A lead angle to the left means that you are flying in a low pressure area. You know what to watch out for!
The cumulus cloud base in ft is determined by multiplying the spread (temperature% dew point) by 400.
Example spread 10 = 10 x 400 = 4000. The cloud base is 4000 ft above ground. This method is most accurate for convection clouds that form around mid-day. It enables thermals to be largely avoided.
If the temperature drops by more than 2 ° C for every 1000 ft increase in altitude, there is a risk of thunderstorms.
The vertical temperature gradient is a measure of the equilibrium state of an air stratification. If the current altitude temperature is lower than the predicted one, i.e. if it is colder than assumed, we find a less stable air stratification.
Thunderstorms have the least impact on their front and the side from which they regenerate, as can be seen from the wind currents at low altitudes.
Thunderstorms usually move in the direction of the wind prevailing at 18,000 ft and are mostly triggered by winds from the south.
Things go wrong from high to low.
The altimeter reads too high when flying from an area of high pressure or high temperature to an area of low pressure or low temperature.
It is colder in high pressure areas than in low pressure areas.
Low pressure air masses rise, while high pressure air sinks from cooler layers. It is also important that warmer air can absorb and hold more moisture than colder air.
The normal approach speed is calculated from the stall speed in the landing configuration x factor 1.3.
On the airspeed indicator, this is the speed at the beginning of the white arc x 1.3.
In gusty winds, the normal approach speed should be increased by half the difference between wind speed and peak gust.
Example: Wind speed 10 kts, with gusts of up to 20 kts. The approach speed increases by 5 Kts. Attention: note the extended landing distance !!!
At a 30 ° angle between the landing and wind direction, the cross wind component is half the wind speed.
It corresponds to approx. 70% of the wind speed at 45 ° and already approx. 85% at 60 °. At 90 ° the wind speed is of course equal to the cross wind component.
The maximum permissible cross wind component of an aircraft is specified with a cross wind of 90% and a wind speed that is 20% of the stall speed.
This maximum crosswind component permitted according to FAA guidelines does not represent a limit that the aircraft could not exceed - rather, it represents a value that a well-trained pilot can achieve under otherwise favorable conditions (and which has also been tested or proven accordingly) .
Aqua-planing speed is obtained by multiplying the square root of tire pressure in pounds by 9.
For a light twin with a tire pressure of 36 pounds, aqua-planing will start at a speed of 54 kts. This means that under these conditions on a wet runway from 54 kts only an aerodynamic brake is effective!
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