CAR / ACF HP

Question 1

High power rocket airframes may be constructed from lightweight materials including wood, phenolic, fiberglass,
plastics and metals.
a) True
b) False

Answer 1

A

Question 2

Single use high power rocket motors may be reloaded.
a) True
b) False

Answer 2

B

Question 3

It is unlawful to alter commercially manufactured high power motors.
a) True
b) False

Answer 3

A

Question 4

What types of payloads are prohibited for on board flight in high power rockets?
a) Incendiary devices
b) Explosive devices
c) Live vertebrate animals
d) All of the above

Answer 4

D

Question 5

What are 3 methods, which can be used to shift the center of gravity of a rocket forward?
a) Add weight to the nose, lengthen the rocket and move the fins back.
b) Add weight to the nose, lengthen the rocket and use a smaller (lighter) motor.
c) Add weight to the nose, shorten the rocket and use a smaller motor.

Answer 5

B

Question 6

Which motor has a higher total impulse?
a) J135
b) J415
c) K185

Answer 6

C

Question 7

Assuming a full 2560 Ns K motor, a K1100 will bum out twice as fast as a K550.
a) True
b) False

Answer 7

A

Question 8

Assume a rocket 200 cm tall with a body diameter of 7.5 cm. The Center of Gravity is 7.5 cm behind the Center of
Pressure. This is a stable design for a high power rocket.
a) True
b) False

Answer 8

B

Question 9

What is the purpose of drilling a vent hole in the body tube above the upper bulkhead and below the nose cone?
a) To prevent premature ejection of the nose cone.
b) To prevent a vacuum from forming in the body tube preventing the nose cone from being able to eject.
c) To prevent a vacuum from forming in the body tube resulting in the body tube shredding upon ejection.

Answer 9

A

Question 10

Electronic or remote firing circuits may be armed in the prep area prior to installation of the high power rocket on
the launch stand.
a) True
b) False

Answer 10

B

Question 11

Redundant or back up recovery systems are required for vehicles when they exceed:
a) 1 kg mass
b) 5 kg mass
c) 10 kg mass
d) 15 kg mass
e) Never

Answer 11

B

Question 12

Fiberglass recovery wadding is allowed by the CAR/ACF safety code.
a) True
b) False

Answer 12

B

Question 13

Electrical igniters may be safely installed in High Power Rocket motors prior to transport to the launch stand.
a) True
b) False

Answer 13

B

Question 14

Rocket motors in excess of a total impulse of 40,960 Ns fall within the Requirements for Launching High Power
Rockets in Canada.
a) True
b) False

Answer 14

B

Question 15

What are three methods, which can be used to shift the Center of Pressure of a rocket aft?
a) Make the rocket shorter, use larger fins and increase the number of fins.
b) Make the rocket longer, use larger fins and increase the number of fins.
c) Make the rocket shorter, add weight to the nose and use larger fins.

Answer 15

A

Question 16

An igniter installed in a motor should be continuity checked before the rocket is taken to the launch pad.
a) True
b) False

Answer 16

B

Question 17

When flying a single stage or multi-stage vehicle, what is the safest, most reliable number of motors to use in
each stage?
a) One
b) Two
c) Three
d) It makes no difference

Answer 17

A

Question 18

Igniters for rockets powered by a cluster of motors must be wired in:
a) Parallel
b) Series
c) Either a or b

Answer 18

A

Question 19

Which type of propellant ignites the quickest?
a) Composite
b) Black Powder
c) Both a and b

Answer 19

B

Question 20

The Barrowman equation may be used to calculate the drag coefficient?
a) True
b) False

Answer 20

B

Question 21

For a rocket to achieve stable flight the center of gravity (CG) must be located in front of the center of pressure
(CP).
a) True
b) False

Answer 21

A

Question 22

The static stability of a rocket is often measured by the distance between the CG and the CP divided by the body
diameter. For a rocket to be stable the CP should be how many body diameters behind the CG?
a) 0.25 caliber
b) 0.50 caliber
c) 1.00 caliber
d) 1.50 caliber

Answer 22

C

Question 23

In comparison to a calm day, on windy days a shorter than usual delay should be selected for any given rocket.
a) True
b) False

Answer 23

A

Question 24

Fins placed forward of the center of gravity will tend to stabilize an unguided rocket in flight.
a) True
b) False

Answer 24

B

Question 25

Ammonium nitrate is the most common oxidizer used in solid reloadable rocket motors. a) True b) False

Answer 25

B

Question 26

The tendency for unguided rockets to 'weather cock" increases with the area of the fin. a) True b) False

Answer 26

A

Question 27

Electric match igniters are not susceptible to discharge by static electricity. a) True b) False

Answer 27

B

Question 28

Calculate the average thrust for a rocket motor with a total impulse of 1280 Ns and a burn time of 10.0 seconds. a) 28.76 N b) 128.0 N c) 67.0 N d) None of the above

Answer 28

B

Question 29

Calculate the average thrust for a rocket motor with a total impulse of 2560 Ns and a burn time of 5 seconds. a) 512.0 N b) 51.20 N c) 128.0 N d) None of the above

Answer 29

A

Question 30

Which of the following igniters requires the greatest current to initiate? a) Solar igniters b) Wire wrap thermalite c) Squibs or electric matches d) Copperhead igniters e) Flashbulb igniters

Answer 30

D

Question 31

The total impulse for a given weight of composite fuel is more than twice that of black powder. That is why solid high power rocket motors use composite rather than black powder. a) True b) False

Answer 31

A

Question 32

All high power rockets must be inspected by CAR/ACF qualified rocket inspector prior to flight. a) True b) False

Answer 32

A

Question 33

The coefficient of drag increases with the length of the rocket airframe. a) True b) False

Answer 33

A

Question 34

Where should an igniter be placed in a composite motor? a) At the top of the core b) In the middle of the core c) At the bottom of the core d) Position makes no difference

Answer 34

A

Question 35

If the general rule of thumb for the minimum average thrust to weight ratio is 4:1, what is the maximum mass of a rocket that the following motors will safely lift? (2 Marks) a) H65 ______kg b) L1000 ______kg

Answer 35

a) 1.66 kg. 65 Ns / 4 = 16.25 N / 9.8 m/s2 = 1.66 kg. b) 25.51 kg. 1000 Ns / 4 = 250 N / 9.8 m/s2 = 25.51 kg.

Question 36

If the general rule of thumb for the minimum average thrust to weight ratio is 4:1, what is the maximum mass of a rocket that the following motors will safely lift? (2 Marks) a) I211 ______kg b) M1439 ______kg

Answer 36

a) 5.38 kg. 211 Ns / 4 = 52.75 N / 9.8 m/s2 = 5.38 kg. b) 36.71 kg. 1439 Ns / 4 = 359.8 N / 9.8 m/s2 = 36.71 kg

Question 37

A rocket has been equipped with a cluster of 3 motors, a central J415 and 2 outboard G-80's. Electric matches are used to ignite the motors. Assuming all 3 electric matches ignite at the same time: a) The J415 will ignite first. b) The 2 G-80’s will ignite first. c) All three motors will ignite at the same time.

Answer 37

b) The 2 G-80's will light first. The core in the J415 is much larger, therefore requiring a much longer period of time to build up sufficient pressure to fully ignite. It is for this reason that clustered projects should be either: 1- Able to lift off safely under the power of the smallest motor in the cluster. 2- The smaller motors should be set on a time delay, where they do not light until after the largest motor in the cluster has come up to full pressure. This is often accomplished by using a G-switch timer, which is set to ignite the smaller motors at a specific time after lift-off is detected.

Question 38

Which answer best describes the typical operation of a nitrous oxide hybrid rocket motor? a) The nitrous is ignited and then released, blowing a hot flame onto the fuel in the combustion chamber. b) The fuel is ignited and the nitrous is then released onto the burning fuel in the combustion chamber. c) The nitrous is combined with the fuel in the combustion chamber, becoming highly flammable and is then ignited.

Answer 38

B

Question 39

What happens when changing to smaller or fewer injector orifices in an ideal hybrid rocket motor (assume the oxidizer weight stays the same)? a) The total impulse decreases and the average thrust increases. b) The total impulse stays the same and the average thrust increases. c) The total impulse stays the same and the average thrust decreases.

Answer 39

C

Question 40

What is the oxidizer most commonly used in a commercial hybrid rocket motor? a) N2O b) N2O4 c) NO2

Answer 40

A

Question 41

What is the nominal tank pressure of a nitrous oxide hybrid motor at 24°C (75°F)? a) 689 kPa (100 psi) b) 4971 kPa (721 psi) c) 10342 kPa (1500 psi)

Answer 41

B

Question 42

Above what temperature does pressurized nitrous oxide change to a gas? a) 36°C (97°F) b) 24°C (75°F) c) 3°C (37°F)

Answer 42

A

Question 43

The boiling point of nitrous oxide at atmospheric pressure is: a) -55.7°C (-68.3°F) b) -73.3°C (-99.9°F) c) -88.5°C (-127.3°F)

Answer 43

C

Question 44

Nitrous Oxide is: a) A hydrocarbon fuel b) An oxidizer c) An acid

Answer 44

B

Question 45

Nitrous Oxide is: a) Highly regulated and available only with proper permits and authorization. b) A controlled substance available only through the medical community. c) Available at most high performance automobile shops.

Answer 45

C

Question 46

The thrust curve of a regressive burn motor has a high initial thrust relative to the ending thrust of the motor. a) True b) False

Answer 46

A

Question 47

The thrust curve of a progressive burn motor has a low initial thrust relative to the ending thrust of the motor. a) True b) False

Answer 47

A

Question 48

The safest burn rate for a rocket whose thrust to weight ratio is marginal is: a) Regressive burn b) Progressive burn c) Makes no difference

Answer 48

A