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Feature Article: Performance Sheet ASEL
Compute weight and balance with gross takeoff weight___________
Center of gravity location ________
Gross landing weight __________ Center of gravity location _________
Shift weight from _________ to the _____________New center of
gravity locaton _________
Cross Country Flight Plan
Total distance is __________Total time is ____________Total fuel
used is __________
Total fuel remaining including reserve ___________Is a fuel
stop required for this flight? ____
Plan takeoff over a 50’ obstacle at full gross weight
at sea lever with an outside air termperature of 30 degrees centigrade
____________
Discuss density altitude and performance.
Plan a landing over a 50 foot obstacle at landing weight at
3000’ pattern altitude with an a standard outside air temperature.
Whis is the best endurance altitude and power setting for this
aircraft? _________
What is the range of this aircraft at 75% power? ________ amd
65% power?_______
Weight affects the stall speed of an airplane. Book figures
are at gross weights. An overweight plane will stall before the
book figure; a light plane will stall at a slower speed. Flight
in excess of gross weight is prohibited. Alaska allows 10% over
for survival gear. Most aircraft are close to gross when they
have full fuel. Reduction of fuel load is the best adjustment
factor.
Controls are designed and certified to perform properly within
a certain balance/speed range. Va or maneuvering speed (abrupt
control movement allowable) is published for gross weight only.
An out-of-balance plane at low speeds may not have the effectiveness
required for control. This means that the elevators may not be
able to properly raise the nose of an airplane while taking off
or landing. They may not be able to effectively lower the nose
in climb, slow flight or landing. All performance figures are
predicated on a properly balanced aircraft. An aircraft that is
out-of-balance causes performance figures to change for the worse.
This is especially true regarding fuel consumption.
Takeoff data is figured for standard conditions with factors added
for wind velocity and runway conditions. Since conditions are
seldom standard, you must compute any effects of density altitude
or non-standard conditions. Climb is figured likewise. The performance
increases at roughly the percentage of the weight reduction. Fly
10 % below gross weight expect takeoff climb and range to improve
about 10%.
Fuel consumption may be determined by power applied. Altitude
normally decreases the air available to the fuel mixture making
possible a reduction (leaning) of the mixture. At altitude the
engine has less power and consumes less fuel while at the same
time getting more distance. In no wind/tail wind conditions it
is more economical to fly high. Density altitude conditions affect
fuel/air relationships as well. Fuel consumption, leaned, is about
.44 pounds of fuel per hour per horsepower. For the C-150 this
gives, .44 X 100 hp /6 lb. per gal = 7.3...gallons per hour. With
22.5 useful capacity and the tanks not really topped off (prevents
waste) three hours flight time with the required 1/2 hour daytime
reserve comes up short. The manual gives more optimistic figures
predicated on lower horsepower available at altitude.
The true air speed (TAS) is calibrated airspeed (CAS) corrected
for air density. This is the manufacturers manual speed, which
you use for navigational purposes to find ground speed. For practical
use it is too optimistic due to the differences between new and
abused (sic) aircraft. The service ceiling is required knowledge
since it makes no sense to plan a flight across terrain above
aircraft capability. At service ceiling the plane can still climb
100 feet per minute. Density altitude factors can greatly affect
both this ceiling and the absolute ceiling.
The V speeds are determined through exhaustive study by the
manufacturer to be the best speeds for a specific desired performance.
While these speeds may vary somewhat with aircraft weight they
are required knowledge as a base for performance. V speeds are
indicated speeds, which are to be flown within the ranges, specified
in the Practical Test Standards. V speeds are usually found near
the front of the aircraft annual with explanation. It is best
to locate, and know for the flight test, the significance and
number of all the V speeds such as: Vx, Vy, Va, Vne, Vfe, etc.
Broad performance - specifications of the aircraft are on back
of the front cover or on the first few pages of the manual. For
specific performance under conditions see the chapter index. Putting
labeled tabs on certain charts related to takeoff, landings, emergency,
and power settings would make location easier. FAR 91.103 requires
that we calculate required runway lengths for takeoff and landing.
You need not know everything in the manual but you must be able
to locate desired information efficiently. It is not recommended
to ever fly without a manual available. Va, maneuvering speed,
is slower at lighter weights. So are stall speeds. The maneuvering
speed is a limit on control movement. Since the aircraft loading
moments between control pressures and turbulence pressures differ,
the allowable turbulence speed may be a bit higher than Va.
Since the use of flaps and slips varies so widely between aircraft,
it is important to know what is specifically required, permitted
or prohibited for your aircraft. The stronger the cross winds
the fewer degrees of flap recommended. The maximum demonstrated
crosswind component is not a limitation. It is something required
as a demonstration. Make sure to know under what conditions slips
are allowed or not. For takeoff be sure to know the required flap
setting for specific performance. Partial and full flap settings
may have different airspeed limits. Application of flaps before
slowing to required speeds will be harmful to the aircraft. The
way flaps are removed in flight depends upon the airspeed. Below
Vx they should be milked off slowly until Vy is obtained while
holding altitude. At Vy or higher removing the flaps all at once
should not create a problem.
It is advisable to have your own manual for every aircraft
you fly.
Last Modified April 24, ©2024 TAGE.COM
