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View Full Version : Last minute Performance questions


Chintito
6th Jun 2004, 00:27
im getting conflicting answer from different people with some of these questions. would someone care to put their neck out and have a go at these.


1. The buffet onset boundary chart tells the pilot:

a. Critical Mach number for various masses and altitudes.
b. Values for low speed stall and mach buffet onset for various masses and altitudes.
c. Mach number for low speed stall and shock stall for various masses and altitudes.
d. Maximum operating M# for various masses and altitudes.

B&C are both marked as correct answers by one set of feedback i have.

2. An aircraft is climbing at a constant IAS, below the Mach limit. As height increases:

a.Drag decreases because density decreases.
b. Drag remains constant but the climb gradient decreases.
c. Drag increases because TAS increases.
d. Drag remains constant and the climb gradient remains constant.

3. In a climb, at the crossover point between V speed (280kts) and Mach number (0.78) speed, do you:

a.Accelerate to the Mach number.
b. Find that there is no change because at the temperature and altitude the Mach number and TAS are exactly the same (29,200 feet).
c. Find that rate of climb would increase.
d. Find that rate of climb would decrease because TAS would start to decrease.

some say C, others D

4. The tangent from the origin to the power required curve for a jet aircraft gives:
a.The max endurance speed
b. The max range speed
c. VMD
d. The long range cruise speed

B or C?

5. If an aircraft is descending at a constant Mach number :
a) The IAS will increase and the margin to low speed buffet will decrease.
b) The IAS will increase and the margin to low speed buffet will increase.
c) The IAS will decrease and the margin to low speed buffet will decrease.
d) The IAS will decrease and the margin to low speed buffet will increase.

6. For a given take off mass, the brake energy limit speed VMBE (IAS) will:
Decrease with increasing altitude, and decrease with increasing temperature,.
b. Increase with increasing altitude and increase with increasing temperature.
c. Decrease with increasing altitude, and increase with increasing temperature.
d. Not change with altitude, but decrease with increasing temperature.

7. At long range cruise speed and at constant level

a) Drag decreases
b) Drag increases
c) IAS decreases
d) TAS increases

long range cruise speed gives 1.32 VMD which would mean drag increasing. answer given is A.


thanks folks

sexygirl
6th Jun 2004, 00:47
1.B
2.B
3.C
4.A
5.B
6.B
7.A

No worries...

High Wing Drifter
6th Jun 2004, 07:40
I think Q 4 is D Vimd (Vmd). Endurance Vspeed depends on whether the a/c is a prop or a jet and is not specified.

Q 6 is, I think A. The lower air density and high temprature slows cool thus reducing Vmbe. Chart 4.7 in CAP 698 confirms this.

paulfer
6th Jun 2004, 09:31
Answer to 4 is b and c???

High Wing Drifter
6th Jun 2004, 10:05
Ans for Q4 It can only be B for a prop and not a jet with is 1.32Vimd. The best answer IMHO is C