38 Design Features

Question 1

How does the T38 having a symmetrical wing affect lift and drag?

Answer 1

Symmetrical wings produce less lift than cambered wings. There is less drag with a symmetrical wing

Question 2

How does the T38 having a low aspect ratio affect lift and drag?

Answer 2

Low aspect ratio wings produce less lift and have a higher stall airspeed at any given AOA.
They have lower parasite drag and better yaw stability, but higher induced drag

Question 3

Does a low aspect ratio wing require a lower or higher AOA for max lift?

Answer 3

Higher

Question 4

Is a low aspect ratio wing less or more sensitive to AOA changes?

Answer 4

Less sensitive

Question 5

How does the T38 having a wing taper affect lift and drag?

Answer 5

A wing taper reduces induced drag and moves the lift distribution by moving the center of wing loading closer to the wing root.

Question 6

How does a wing taper affect where a wing stalls first?

Answer 6

A wing with wing taper causes the wing tips to stall first, which can cause sudden rolls near stalls

Question 7

What 3 things about the T-38’s wing design affect its high speed flight characteristics and why?

Answer 7

1. Symmetrical Wing
2. Low Aspect Ratio
3. Wing Taper

There is less parasitic drag and lift

Question 8

What is the key factor when determining the speed of sound?

Answer 8

Temperature

Question 9

What is mach number (equation)?

Answer 9

TAS/Speed of Sound

Question 10

What happens to Mach number as you increase in altitude?

Answer 10

TAS remains constant while Mach number increases

Question 11

What happens to CAS/IAS as you increase altitude?

Answer 11

CAS/IAS decrease as altitude increases

Question 12

What is the critical mach number?

Answer 12

The lowest freestream speed at which some point in the air flow around the aircraft reaches the speed of sound

Question 13

What is force divergence mach number?

Answer 13

The speed where wave drags begin throughout the transonic regime (5-10% above critical mach)

Question 14

What is wave drag?

Answer 14

Shock waves decrease lift and increase parasitic drag due to air slowing when shock waves decelerates the air flowing around it

Question 15

What happens to the T38’s flight characteristics at transonic and supersonic airspeeds and why?

Answer 15

The T38 becomes more stable and less maneuverable

Due to the Aerodynamic center is moved farther AFT of the CG, creating greater longitudinal pitch stability

Question 16

What is aspect ratio?

Answer 16

The actual
aspect ratio (AR) of a wing is equal to the wingspan (b) squared, divided
by the wing area (S).

Question 17

What is the T38s aspect ratio?

Answer 17

3.75

Question 18

What is the 38s wing taper ratio?

Answer 18

0.2

Question 19

What is wing taper ratio?

Answer 19

The reduction in chord length from root to tip

Question 20

What is the T38s wing sweep back angle?

Answer 20

24 degrees

Question 21

How is wing sweep measured?

Answer 21

The quarter chord sweep angle, which is

measured between the lateral axis and a line 25 percent of the way back from the leading edge of the wing

Question 22

How does the area rule effect the T38 and what is the area rule?

Answer 22

The cross-section area of the aircraft should change gradually and smoothly as you move
from the nose to the tail. This design minimizes the need for abrupt changes in airflow and the associated drag

Question 23

What is the definition of transonic flow?

Answer 23

Mixed airflow around the aircraft that is part subsonic and part supersonic