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Wednesday 3rd December 2008
Brainteasers
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March 24, 2005

Brainteasers
Interactive Quiz #92:
Load Factors and Fictions

If the airplane has four seats, you can cram in four people, right? Perhaps not. The PIC must not only figure how much weight is being carried but how that load affects safety. Are you balanced?

INSTRUCTIONS: Answer the questions as best you can, then click on the "Score my quiz answers" button to see your score and read the explanations. If you don't like your score the first time around, you can change some of your answers and resubmit. To get the most out of this quiz, we suggest you keep trying until you get a perfect score.

NOTE: When more than one answer is true, only the most complete, correct answer will be scored as correct. The answers are assumed to apply within the United States unless otherwise noted.

1. Your hangar neighbor, "Fearless" Filbert, recently purchased a single-engine, six-seat, Sky Mangler IV because his old four-seat Cherokee couldn't haul enough. Proudly thumping the cowling over the normally aspirated, 300-horsepower engine with its constant-speed propeller, Filbert explains, "She'll haul anything you can close the doors on." To prove it, he offers to fly his bowling team to a tournament in Leadbutte, Mont. With six adults, full fuel, bowling balls -- two each -- and baggage, the doors barely latch. The aircraft is over max. gross weight, but Filbert says, "No problem. The runway's long, I'm at sea level, and, besides, by the time we get there, I'll have burned off enough fuel to land within weight limits. He tosses the POH into the baggage compartment to emphasize his point. Being familiar with that model aircraft, however, you note that the CG will shift aft as fuel burns. This aft-CG situation potentially causes (among other things):
a. Faster cruise and better stall recovery
b. Faster cruise and more difficult stall recovery
c. Slower cruise and better stall recovery
d. Slower cruise and more difficult stall recovery
2. Given your answer to the previous question, consider this: As the CG moves forward -- all the bowling balls come lose and roll beneath the front seats, where they remain -- the airplane will stall at a higher speed, because the stalling angle of attack is reached at a higher speed due to increased wing loading.
a. True
b. False
3. Filbert's airplane has two baggage compartments; one is located at the aft end of the cabin (140 inches aft of the datum, which for this imaginary airplane is the firewall), and the other baggage area is 10 inches forward of the firewall. Filbert realizes that with full tanks he'll be 100 pounds over max. takeoff weight. But, an idea dawns! Because the nose baggage area is forward of the datum with a negative arm (-10), he can shift some baggage from the aft compartment to the nose to redistribute the load. How much weight must Filbert shift from the aft baggage compartment to the nose in order to take off at or below max. takeoff weight? (Choose the best answer. Round up or down as necessary. Consider ramp and takeoff weights to be the same.)
a. 16.6 pounds (about one bowling ball)
b. 166.6 pounds
c. 100 pounds
d. None of the above
4. (Fill in the blanks.) Filbert normally flies his final approach at 90 KIAS (knots indicated airspeed). As he approaches his high-altitude destination (airport elevation 7000 feet MSL), he nails the airspeed needle at exactly 90 knots, the same speed he uses at sea level. He's that good. All other variables aside (wind, heat, humidity, humility), his true airspeed (TAS) will be (_____) and groundspeed (GS) will be (_____). For our purposes here, IAS and CAS are identical.
a. TAS higher than 90, GS higher than 90
b. TAS higher than 90, GS less than 90
c. TAS less than 90, GS higher than 90
d. TAS less than 90, GS less than 90
e. Not different than IAS.
5. Same airport used in the previous question. The reported temperature is 15ºC (59ºF), which is standard. Altimeter setting is 29.92 inches; ignore humidity for this question. Density altitude will equal field elevation -- 7000 feet -- right?
a. True
b. False
6. Enough fun with "Fearless" Filbert. Time to cinch your shoulder harnesses and think acro -- loops, rolls, and nausea in unusual attitudes. Before heading up to strain your eyeballs, though, you should know that modern airplanes are certified in three operational categories: Normal category airplanes must withstand a load factor (ratio of the maximum load an aircraft can sustain to the total weight of the aircraft) of 3.8 times their weight, utility airplanes must withstand 4.4 times, and the acrobatic airplane minimum limit is what? (Ignore any designed or implied buffers beyond these limits. Think positive.)
a. 5.4
b. 6.0
c. 6.4
d. 7.2
7. (Fill in the blanks.) As you bank an airplane in flight (not on the ramp) while maintaining altitude, load factor (_____) and stall speed (_____).
a. Decreases, decreases
b. Increases, decreases
c. Increases, increases
d. Decreases, increases
e. Remains constant, remains constant
8. In a constant, coordinated, 60-degree banked steep turn, you apply back pressure to the yoke and your one-pound key chain exerts two pounds of "weight." That extra 10 pounds you gained over the holidays and swore you'd lose by spring now feels like 20 pounds. In short, you're pulling 2 Gs -- twice gravity. Two forces cause this load factor in the turn: One is gravity itself -- the 1 G pull of the earth -- and the other is what force?
a. Inertial (centrifugal)
b. Phugoid
c. Aneroid
d. Thrust
e. Drag
9. The load factor in level, unbanked flight is 1 G. The load factor for any airplane in a 60-degree bank is 2 Gs. What is the load factor in an 80-degree bank?
a. 2.76 Gs
b. 3.76 Gs
c. 4.76 Gs
d. 5.76 Gs
10. (Fill in the three blanks.) The maximum speed at which an airplane may be stalled safely is called the (_____) (V_____) and is required to be entered in the (_____) of all recently designed airplanes.
a. Best angle-of-incidence speed (Vs). Entered in FAA-approved Airplane Flight Manual or Pilot's Operating Handbook (AFM/POH) of all recently designed airplanes.
b. Design maneuvering speed (Va). Entered in the FAA-approved Airport/Facility Directory or Pilot's Operating Handbook (AFD/POH) of all recently designed airplanes.
c. Design maneuvering speed (Va). Entered in the FAA-approved Airplane Flight Manual or Pilot's Operating Handbook (AFM/POH) of all recently designed airplanes.
d. Best reference speed (Vref). Entered in the FAA-approved Airplane Flight Manuel or Pilot's Operating Handbag (AFM/POH) of all decently resigned airplanes.