1. PRINCIPLES OF FLIGHT THRUST AND DRAG CHAPTER 2 BLACKBURN BEVERLEY C1
JUST THINK OF THE POWER REQUIRED
TO GET THIS AIRCRAFT FLYING.

2. THRUST TO PRODUCE LIFT THE WINGS OF THE
PRINCIPLES OF FLIGHT
THRUST
TO PRODUCE LIFT THE WINGS OF THE
AIRCRAFT MUST HAVE AIR FLOWING OVER
THEM.
THE AIRFLOW IS PRODUCED BY “THRUSTING”
THE AIRCRAFT FORWARD.
THE ENGINE OR ENGINES PROVIDE THE
THRUST TO PRODUCE THE AIRFLOW.
ENGINES PRODUCE THRUST EITHER BY
A PROPELLOR SCREWING THE AIR BACKWARDS,
OR A JET ENGINE EXPELLING AIR FROM THE REAR CASING OF THE ENGINE.

3. THRUST IN BOTH CASES, THROWING THE AIR BACKWARDS THRUSTS THE AIRCRAFT
PRINCIPLES OF FLIGHT
THRUST
IN BOTH CASES, THROWING THE AIR
BACKWARDS THRUSTS THE AIRCRAFT
FORWARDS.
NEWTON’S 3RD LAW
EVERY ACTION HAS AN EQUAL
AND OPPOSITE REACTION.
THE THRUST ACTS ALONG A LINE
APPROXIMATELY FROM THE NOSE TO THE
TAIL OF THE AIRCRAFT.
THE AMOUNT OF THRUST IS SELECTED BY
THE PILOT.

4. CRASHING ! YOU NEED LOTS OF THRUST TO STOP YOU -
PRINCIPLES OF FLIGHT
THRUST CAN BE VERY IMPORTANT
IF YOU FORGET TO PUT YOUR UNDERCARRIAGE
DOWN.
YOU NEED LOTS OF THRUST
TO STOP YOU -
CRASHING !

5. PRINCIPLES OF FLIGHT
RIAT PRACTICE DAY

6. DRAG WHO RIDES A BICYCLE ? WHAT HAPPENS WHEN YOU INCREASE SPEED ?
PRINCIPLES OF FLIGHT
DRAG
WHO RIDES A BICYCLE ?
WHAT HAPPENS WHEN YOU INCREASE SPEED ?
YOU GET MORE AIR RESISTANCE.
THIS IS CALLED “DRAG”
EVERY EXTERNAL PART OF AN AIRCRAFT
PRODUCES DRAG WHICH RESISTS FORWARD
MOTION.
AS WE DID WITH THE CENTRE OF PRESSURE,
WE TAKE THAT THE TOTAL DRAG OF THE
AIRCRAFT ACTS ALONG A LINE FROM THE
NOSE TO THE TAIL OF THE AIRCRAFT
DIRECTLY OPPOSING THRUST.

7. DRAG THE GREATER THE DRAG THE GREATER THE
PRINCIPLES OF FLIGHT
DRAG
THE GREATER THE DRAG THE GREATER THE
ENGINE POWER IS NEEDED TO OVERCOME IT.
MORE THRUST = MORE ENGINE POWER
MORE ENGINE POWER = LARGER ENGINES
LARGER ENGINES = MORE FUEL
MORE FUEL = MORE WEIGHT
THE AIRCRAFT DESIGNER IS RESPONSIBLE
FOR DECIDING WHAT IS THE MOST EFFICIENT
WAY OF ACHIEVING THE ROLE OF THE
AIRCRAFT.
WHAT CAUSES DRAG ?

8. Lots of drag and weight and not enough power, even with 8 engines.
PRINCIPLES OF FLIGHT
THE SPRUCE GOOSE
Lots of drag and weight and not enough power, even
with 8 engines.
Only flew once and only to 10ft off the ground.

9. DRAG DRAG IS CAUSED BY THE SHAPE OR “FORM” OF THE AIRCRAFT PARTS.
PRINCIPLES OF FLIGHT
DRAG
DRAG IS CAUSED BY THE SHAPE OR “FORM” OF
THE AIRCRAFT PARTS.
WHEN AN OBJECT MOVES THROUGH THE AIR
IT LEAVES A TRAIL OF VORTICES AND EDDIES.
AN EXTREME EXAMPLE OF THIS IS A FLAT
PLATE.
90° TO AIRFLOW
PARALLEL TO AIRFLOW

10. DRAG DRAG IS BEST ELIMINATED AT THE DESIGN
PRINCIPLES OF FLIGHT
DRAG
DRAG IS BEST ELIMINATED AT THE DESIGN
STAGE, BY HAVING THE LEAST EXTERNAL
PROTRUDING PARTS AS POSSIBLE.
BAGS OF DRAG

11. DRAG STREAMLINING THE FORM OF AN AIRCRAFT WILL REDUCE THE DRAG.
PRINCIPLES OF FLIGHT
DRAG
STREAMLINING THE FORM OF AN AIRCRAFT
WILL REDUCE THE DRAG.
STREAMLINING MAKES THE AIRFLOW AS
SMOOTH AS POSSIBLE AND REDUCES WAKE.

12. DRAG STREAMLINING CAN REDUCE THE DRAG OF A FLAT PLATE BY 95%.
PRINCIPLES OF FLIGHT
DRAG
STREAMLINING CAN REDUCE THE DRAG OF A FLAT PLATE BY 95%.

13. Form Drag VERY TURBULENT WAKE REDUCTION IN FORM DRAG 50% 85% 90 - 95%
PRINCIPLES OF FLIGHT
VERY TURBULENT WAKE
REDUCTION IN FORM DRAG
50%
85% %

14. DRAG IN A STREAMLINED FORM THE RATIO OF IT’S
PRINCIPLES OF FLIGHT
DRAG
IN A STREAMLINED FORM THE RATIO OF IT’S
WIDTH TO IT’S LENGTH IS KNOWN AS:-
“THE FINENESS RATIO”
DESIGNING THE FORM TO HAVE A FINENESS
RATIO OF 3 OR 4 TO 1 KEEPS THE WAKE TO
A MINIMUM.
AS WITH LIFT THE AMOUNT OF DRAG VARIES
WITH THE SQUARE OF THE AIRSPEED:
2 x AIRSPEED = 4 x DRAG
3 x AIRSPEED = 9 x DRAG

15. DRAG DRAG IN STEADY STRAIGHT AND LEVEL FLIGHT THRUST EQUALS DRAG.
PRINCIPLES OF FLIGHT
DRAG
DRAG
CofG
THRUST
DRAG
EQUALS
IN STEADY STRAIGHT
AND LEVEL FLIGHT
THRUST EQUALS
DRAG.
CofG
DRAG GREATER
THAN THRUST
AIRCRAFT
SLOWING
DOWN
IF DRAG GREATER THAN
THRUST, THEN AIRCRAFT
SLOWS DOWN.
CofG
AIRCRAFT
GAINING
SPEED
THRUST GREATER
THAN DRAG
IF THRUST IS GREATER
THAN DRAG THEN
AIRCRAFT GAINS
SPEED.

16. LIFT,WEIGHT,THRUST & DRAG
PRINCIPLES OF FLIGHT
LIFT,WEIGHT,THRUST & DRAG
IN STRAIGHT AND LEVEL FLIGHT AT
CONSTANT SPEED, TWO PAIRS OF
FORCES ACT ON THE AIRCRAFT.
LIFT OPPOSES WEIGHT AND IS EQUAL TO IT.
THRUST OPPOSES DRAG AND IS EQUAL TO IT.
LIFT
WEIGHT
DRAG
THRUST

17. THE BLACKBURN BEVERLEY DID FLY
PRINCIPLES OF FLIGHT
THE BLACKBURN BEVERLEY DID FLY