Questions on "Engines [Gas Turbines]"

[truefaith]

Can somebody kindly help me? :)

Q1. The reason for the reduction in thrust setting with increase ub altitude is:
(a) increase in TAS for samw as IAS
(b) decrease in ambient temperature causing greater temperature difference in the process
(c) increase in EAS for same IAS

Q2. For a given engine RPM and gas temperature at sea level and ISA conditions:
(a) fuel delivery from the burners is smallest
(b) fuel delivery is not affected by altitude
(c) fuel delivery from the burners is greatest

Q3. Taking air from compressor for pressurisation and engine deicing will result in:
(a) high EGT and high specific fuel consumption
(b) low EGT and low specific fuel consumption
(c) high EGT and low specific fuel consumption

Q4. Engine running at constant RPM for a free turbine engine the RPM:
(a) cannot be increased
(b) maybe increased by increased torque pressure
(c) can be increased by propellers

[HazelNuts39]

truefaith;

I think the person who made up these nonsensical questions failed the test.

Regards,
HN39

[truefaith]

Can somebody help? :)


Q5. A pitot intake forms a __ duct ___ the fan to ensure that the airlfow ___ to ___ and achieves a ___.
(a) convergent, before, speeds up, subsonic, pressure rise
(b) divergent, after, slows down, subsonic, pressure rise
(c) divergent, before, speeds up, sonic, pressure drop
(d) divergent, before, slows down, subsonic, pressure rise

Q6. One advantage of an annular combustion chamber system is that:
(a) the diameter of the engine is reduced
(b) there is unrestricted airflow at maximum r.p.m.
(c) there are no flame propagation problems
(d) the air casing area is greater

Q7. Water injection is used for take-off:
(a) to cool the combustion chambers
(b) to cool the turbine blades
(c) only at high altitude airfields where the prevailing temperature is high
(d) at airfields with an ambient temperature above 30F.

Q8. In a high ratio by-pass engine
(a) all of the air go thru both the low and high pressure compressors
(b) not all the air go thru the high poressure compressor
(c) not all the air go thru low pressure compressor
(d) all the air thru the high pressure compressor

Q9. Aft of the compressor
(a) the velocity of the airflow remains the same
(b) the velocity of the airlfow decreases before the combustion chamber
(c) the velocity increases before the combustion chamber
(d) the air pressure decreases before the combustion chamber

[keith williams]

truefaith,

This is the second time that you have asked members to provide answers to a list of questions. All of the questions that you have asked are relatively simple and require only a very limited knolwledge of the subjects.

The overall impression that you have given is that you simply wish to learn the answers instead of attempting to understand the subjects.

You will get a better response if you state which answers you think are correct and explain briefly why you think that they are the correct answers. Readers are then more likely to give you constructive comments including explanations of why you are right or wrong.

You will also learn more from the process.

[truefaith]

@ keith williams

I am sorry. I learn faster by absorbing the correct answer. ;)

If there is any queries about the answer chosen, I will raise it.

_________________________________________________________

Q7. Water injection is used for take-off:
(c) only at high altitude airfields where the prevailing temperature is high
(d) at airfields with an ambient temperature above 30F.
Either (c) or (d), still unsure

HazelNuts39 provided answer with "(b) to cool the turbine blades". Hum... :rolleyes:

Q8. In a high ratio by-pass engine
(b) not all the air go thru the high poressure compressor
(c) not all the air go thru low pressure compressor
Either (b) or (c), still unsure

[truefaith]

Can somebody enlight me? Is it correct? :)

Q1. The reason for the reduction in thrust setting with increase in altitude is:
(a) increase in TAS for samw as IAS

Q2. For a given engine RPM and gas temperature at sea level and ISA conditions:
(c) fuel delivery from the burners is greatest

Q3. Taking air from compressor for pressurisation and engine deicing will result in:
(a) high EGT and high specific fuel consumption

Q4. Engine running at constant RPM for a free turbine engine the RPM:
(a) cannot be increased

[truefaith]

Last set of 7 questions. Can somebody help me to see whether have I chosen the correct answer? Thank you. :sad:

Q10. Appropriate use of carburettor heat:
(a) (OFF) Cold on finals
(b) (OFF) Cold on glide descent without power
(c) (ON) Hot on take off
(d) (ON) Hot in cruise

Q11. Aircraft reverse thrust
(a) only exist in turboprop engine since the turbojet engine does not have the mechanism
to change the direction of the exhaust efflux
(b) aid braking and direction control on ground
(c) used for noise attenuation by reducing the velocity of exhaust efflux
(d) is done by reverse the angle of the turbine blades in turbojet
Not sure is it correct? I chose (b)

Q12. What is the ultimate limitation of the engine for supercharging?
(a) Turbine RPM
(b) Exhaust Gas Temperature
(c) Compressor RPM
(d) Intake Temperature

Q13. Limitation of superchargers:
(a) continue to run without cooling
(b) increase speed without cooling
(c) high temp due to compression
(d) running one at a time


Q14. Entrance to combustion chamber:
(a) continue to run without cooling
(b) increase speed without cooling
(c) airflow slowed down to prevent flameout
(d) running one at a time
Not sure is it correct? I chose (b)

Q16. If engine power is increased with propeller lever in the constant speed range, rpm increase, then:
(a) Governor weights move out, blade angle decrease, rpm decrease, weights remain
(b) Governor weights move in, blade angle increase, rpm decrease, weights move out
(c) Governor weights move out, blade angle increase, rpm decrease, weights move in
(d) Governor weights move out, blade angle increase, rpm decrease, weights move in, blade angle decrease again
Not sure is it correct? I chose (c)

Q17. When the plane goes into descent without increasing power with RPM, airspeed increases, what does the CSU do to maintain constant RPM
(a) increase the blade angle
(b) to remain covered by fuel irrespective of the aircraft attitude
(c) decrease the blade angle
(d) maintain blade angle

[FlyingStone]

I am sorry. I learn faster by absorbing the correct answer.

I always thought that technical subjects should be studied, not learned. You could teach a monkey to pass the ATPL exams or fly the aircraft in certain conditions, but a monkey can't understand the subject.

You shouldn't aim at learning the correct answers, but you should try to understand the subjects you're trying to learn - believe me, the latter is much more simple and you'll gain much more knowledge that way. Given the answers you've provided it's clear you don't understand the subjects at all.

[truefaith]

Can somebody please help? Thank you.

[truefaith]

I think I know the answers to a few of them
Dear Concorde Rules,

Can you kindly help?

[Mad (Flt) Scientist]

@truefaith

He's told you the conditions for him helping: you try first, so that you're doing something more than memorizing combinations of letters and numbers.

You may want to check out some of the responses by experienced pilots in the thread When can you say you know enough to be safe in the cockpit? (http://www.pprune.org/tech-log/456742-when-can-you-say-you-know-enough-safe-cockpit.html) to help you understand why people aren't too impressed by your rote learning approach to aviation .... even people with a lot of experience believe they need to keep learning, yet I'm sure they could memorize an answer sheet quite effectively.

[lomapaseo]

I can't help here

I might understand gas turbines, but I don't understand the questions.

I would rather have a discussion style question than a multiple choice for an unknown engine with an unknown control function on an unknown aircraft.

[dixi188]

Truefaith,

I think you need to take on board what people here are saying. Learning the answers is not the way to understand aircraft systems.

When you take an exam with multi choice answers the idea is to test your knowledge of a sample of all things related to the subject. Your knowledge should be much wider than just the questions asked.

Your knowledge of engines seems to be at a fairly basic level.
e.g. Water injection is used to cool the combustion chamber, not as you thought , only at high temp or altitude. It is (was) often used in high temp conditions but not exclusively so.

For turbine engines I would suggest you get a copy of "The Jet Engine" published by Rolls Royce and "read and inwardly digest" (as my teachers used to say) so you have a better understanding of the subject, and then try to answer the questions yourself. Then if you are having trouble, people here will be only too pleased to help you.

Best regards, Dixi.

[truefaith]

I am getting old and slow in learning.

Can somebody kindly provide the answer? Thank you.

[3holelover]

"Truefaith" ... You sound like a man who wants to get some position you don't have the knowledge to hold. In this business, none of us can tolerate that (when we have a choice).

[BOAC]

Is 'truefaith' blonde, perchance?

[FE Hoppy]

I work for a training provider in Europe. We will gladly provide you with all the answers. Contact our sales division who will sign you up for the appropriate course. Very reasonable fees these days. :ok:

[Slasher]

Its what I've known for a long time - Tech Log is just a quick
way of getting free answers for slobs who are too bloody lazy
to put in the necessary hard work and study. That is why I
reply to only a few threads around here.

Truefaith you admit you're a slow learning bastard (least yer
honest) so I'll be honest too - I'll give you the correct answer
to every question of every exam you have for a fee of $2,000
US (up to max 200 questions, thereafter $15/answer). All my
assistance doesn't come free except to fellow professionals
who have at least gotten off their arses and properly studied
the subject matter, slow learners or not. PM if you're interested.

PS - I don't provide any courses. You just give me the questions and I simply supply the answers.

[Tinstaafl]

For an extra fee, Slasher will also include pictures of buxom, scantily clad women. :E That way, later in your career, you'll have something nice to remember while trying to cope with a faulty system that you don't understand. Quite a bargain, really.

[Hedge36]

How much just for the pictures of buxom, scantily-clad women?

[Turbine D]

Truefaith,

$2000 per answered question is rather pricy, even with pics of scantily clad women thrown in at no additional cost.

Might I suggest you start with this book which costs about $100 US.

Aircraft Gas Turbine Engine Technology written by Irwin E. Treager
ISBN 0-02-801828-1 Glencoe/McGraw-Hill

[lomapaseo]

Reading a book won't help some people. Just sell them the answer that they can memorize.

understanding only helps if someday you want to use the information

[Smilin_Ed]

This is a truly amazing thread. :}

[Slasher]

Ok fair enough. 2,000 bucks for 200 answers I admit is rather
pricey, so yeh alright I'll throw in 100 pics of buxom scantily
clad women for truefaith free. Here's a sample if John the Tulla
doesn't mind -

http://t3.gstatic.com/images?q=tbn:ANd9GcRQDHJ06MXOTlxYCRFpS3lEOeHvxMukA_OfD_274IE I1BukPJxvBQ

You won't find THAT in Aircraft Gas Turbine Engine Technology!

How much just for the pictures of buxom, scantily-clad women?

I provide em free down in the JB dungeon Hedge. You know that! ;)

[Brian Abraham]

Slasher, I bet if you pricked those they'ed go ppppsssstttt - jet reaction just like a gas turbine. Not scantily clad either that one, false advertising.

[rudderrudderrat]

Hi Truefaith,

Slasher has posted a splendid picture of a pair of governor bob weights. As you can imagine, if they were rotated more quickly (rpm increase), they would move out. If the rpm decreased, they would move back in.
I'd have gone for D - twice.

Q16. If engine power is increased with propeller lever in the constant speed range rpm increase, then:
(a) Governor weights move out, blade angle decrease, rpm decrease, weights remain
(b) Governor weights move in, blade angle increase, rpm decrease, weights move out
(c) Governor weights move out, blade angle increase, rpm decrease, weights move in
(d) Governor weights move out, blade angle increase, rpm decrease, weights move in, blade angle decrease again
Not sure is it correct? I chose (c)
Edit Thanks BOAC, I agree, E is probably better

[BOAC]

rrat - why are they called 'bob'? Are they both called 'bob'? You sure you didn't miss an 'o'?

I would disagree with 'D' by the way - "DD" or 'E'.

[V1... Ooops]

Q3. Taking air from compressor for pressurisation and engine deicing will result in:
(a) high EGT and high specific fuel consumption
(b) low EGT and low specific fuel consumption
(c) high EGT and low specific fuel consumption

Q4. Engine running at constant RPM for a free turbine engine the RPM:
(a) cannot be increased
(b) maybe increased by increased torque pressure
(c) can be increased by propellers

Wow, I don't envy you having to write this test. The test questions are (in my opinion, anyway) rather poorly constructed - more of a test of interpretation of grammar and syntax than a test of aviation knowledge.

Anyway, concerning the two questions directly above:

Question 3: If you remove compressed air from the engine for airframe use (pressurization, de-ice, etc.), the combustion chamber temperature will increase and the fuel consumption will increase. This is because you are providing less cooling air to the combustion chamber (you're stealing it to use it in the airframe), and you will need to burn additional fuel to 'make up' the air that you have stolen from the engine to use in the airframe.

Question 4: In a free turbine engine such as a PT-6, the gas generator (the aft, compressor section) RPM is set by the power lever. The power lever sets the governing speed of the compressor. If you vary the rotational speed of the propeller (the forward, power section), this will result in a change in torque indication, but it will not affect the RPM of the gas generator.

Hope this information helps you figure out what the most appropriate of the answers offered is.

Michael

[V1... Ooops]

Q17. When the plane goes into descent without increasing power with RPM, airspeed increases, what does the CSU do to maintain constant RPM
(a) increase the blade angle
(b) to remain covered by fuel irrespective of the aircraft attitude
(c) decrease the blade angle
(d) maintain blade angle

The key to figuring out this question is to consider what would happen to the speed of the propeller if the aircraft airspeed increased (for example, in a descent) and the propeller governor took no action - in other words, if the propeller governor did not change the blade angle as it is supposed to.

If the speed of the aircraft increases (with no change to engine power setting, as would be the case if you just nosed over into a descent) and the propeller governor took no action, the speed of the propeller would also increase.

The purpose of the propeller governor is to keep the propeller turning at a constant RPM regardless of aircraft speed. So, if the speed of the aircraft increases (and the power setting is not changed), the propeller governor will increase the blade angle of the propeller - so that the propeller 'takes a bigger bite of the air' with each turn - and the propeller speed thus remains constant at the speed that the pilot has set using the propeller RPM control.

Similarly, if you attempt to climb without changing the power setting, the aircraft will slow down a bit, and the propeller governor will reduce the propeller blade angle so that the propeller 'takes a smaller bite of the air' with each revolution, and thus maintains the speed you have set with the propeller RPM control.

Michael

[ChristiaanJ]

Its what I've known for a long time - Tech Log is just a quick way of getting free answers for slobs who are too bloody lazy
to put in the necessary hard work and study.A bit unfair, really, Slasher.
Not all of the readers here are test pilots with full engineering degrees, and thousands of hours on both civil and military aircraft.
I've seen answers to questions here I couldn't have found anywhere else.

CJ

[barit1]

When in high school, I encountered a standardized test question that went something like this:

A 100 ohm resistor is dissipating 10 watts. If it is replaced by a 50 ohm resistor, and everything else is unchanged, how much power will be dissipated?

To which I pondered: you can maintain a constant supply voltage, in which case current (and power) will double. OR - you can maintain a constant current, in which case voltage (and power) will be reduced to half. But (by definition) you cannot keep both voltage and current constant!

I answered it as if voltage remained constant, because I was sure the test-writer never comprehended any other way. :ugh:

[barit1]

Turbine D:Might I suggest you start with this book which costs about $100 US.

Aircraft Gas Turbine Engine Technology written by Irwin E. Treager
ISBN 0-02-801828-1 Glencoe/McGraw-Hill

Professor Treager was my instructor at Purdue nearly 50 years ago. One of the best!

[Slasher]

Not scantily clad either that one, false advertising.

If I had've posted anything stronger BA, John Tulla would've
banned me! :ouch:


A bit unfair, really, Slasher.'

Ok CJ I'll rephrase - Tech Log is just a quick way of getting
free answers for some slobs who are too bloody lazy to put in
the necessary hard work and study.