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Thankyou to those of you who gave answers to my previous questions, I have a few more and that will be me done.....
I have tried to search these on here but to no avail....
1. What are differential/non diferential spoilers? (I think I know this one)
2.What are the inputs to Q feel, what is Q feel?
3. What causes a jet up-set? recovery?
4.What is a safety cell battery?
5.What is IRS ?and how is it better than GPS?
6.What is the difference between a dry V1 and a wet V1
7.If you fly in a region of volcanic dust what are the hazards and procedures you would adopt
8.If TOW is limited by an obstacle in the 2nd segment what does that mean???
everyone pick a question then you wont have to do all the work!
cheers
dynamite
I have tried to search these on here but to no avail....
1. What are differential/non diferential spoilers? (I think I know this one)
2.What are the inputs to Q feel, what is Q feel?
3. What causes a jet up-set? recovery?
4.What is a safety cell battery?
5.What is IRS ?and how is it better than GPS?
6.What is the difference between a dry V1 and a wet V1
7.If you fly in a region of volcanic dust what are the hazards and procedures you would adopt
8.If TOW is limited by an obstacle in the 2nd segment what does that mean???
everyone pick a question then you wont have to do all the work!
cheers
dynamite
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I'll answer Q5. Someone else can pick up the rest.
I have to say that I do wonder why you're posting some of this stuff. It is you who is supposed to do the work to become an airline pilot, not me. I've had my career. I did it by hard work, application, and thirst for knowledge, not by setting other people up!
That said, I'm always pleased when people are interested.
IRS (Inertial Reference Systems) are a development of INS (Inertial Navigation Systems).
IRS is a 1990s technology. INS was a 1965-70 technology. There are 3 main differences. (1) System Integration. (2) Laser Gyros. (3) A virtual platform instead of a real one.
I am assuming you know what an INS is. If you don't, then you really are just using us.
(1) If you were an airline which had bought an INS in 1970, it would have been an add-on extra in your Boeing 707 or Caravelle. A new navaid to supplement your VOR/ADF/DME. Sure, it would have had a set of damn fine gyros, but it wouldn't have replaced your ADI/HSI/radar scanner gyros.
These days, we bring the system designer in early. As INS/IRS needs such a good gyro to make it work, why have tacky old ADI/HSI/radar scanner gyros as well? Take everything off the IRS and save duplication.
(2) Laser gyros are cheaper and more accurate than huge rotating lumps of shaped iron. If you want to know more, enrol on the Oxford course.
(3) It's not necessary to have heavy electrical engineering to keep a platform level. Expensive, well-engineered analogue control systems might please engineers, but they go wrong quite often. Why not, instead, bolt the gyros and the accelerometers to the floor instead of trying to keep them level? You can then sort out the directions in 3 planes by complicated computing. That way, all you get is a lot of little 1s and 0s rushing about in a computer processor which is a virtual model of which way is up, instead of the real thing.
IRS isn't 'better' than GPS. GPS is acually more acurate - most of the time! However, it has a different type of reliability. If you have 2, or even better, 3 IRSs on board and you have a system of cross-checking, as each one is totally independent, it's very unlikely that all of them will be wrong to put you in precisely the same (wrong) place. GPS isn't like that. When it's good, it's very very good. But if it's wrong all of your GPS receivers will be the same amount wrong, so you'll never spot the problem. More importantly, on a bad day, you just might not be able to get a sufficiently reliable GPS signal for the thing to work at all.
And don't forget the bottom line. On a bad day, the US Government might just decide to switch GPS off for political or military reasons. Even though one hopes that that's pretty unlikely, the world is an uncertain place and you can never be sure. However, no-one can switch IRS/FMS off. It is totally self-contained within the aircraft. It depends on no-one.
I have to say that I do wonder why you're posting some of this stuff. It is you who is supposed to do the work to become an airline pilot, not me. I've had my career. I did it by hard work, application, and thirst for knowledge, not by setting other people up!
That said, I'm always pleased when people are interested.
IRS (Inertial Reference Systems) are a development of INS (Inertial Navigation Systems).
IRS is a 1990s technology. INS was a 1965-70 technology. There are 3 main differences. (1) System Integration. (2) Laser Gyros. (3) A virtual platform instead of a real one.
I am assuming you know what an INS is. If you don't, then you really are just using us.
(1) If you were an airline which had bought an INS in 1970, it would have been an add-on extra in your Boeing 707 or Caravelle. A new navaid to supplement your VOR/ADF/DME. Sure, it would have had a set of damn fine gyros, but it wouldn't have replaced your ADI/HSI/radar scanner gyros.
These days, we bring the system designer in early. As INS/IRS needs such a good gyro to make it work, why have tacky old ADI/HSI/radar scanner gyros as well? Take everything off the IRS and save duplication.
(2) Laser gyros are cheaper and more accurate than huge rotating lumps of shaped iron. If you want to know more, enrol on the Oxford course.
(3) It's not necessary to have heavy electrical engineering to keep a platform level. Expensive, well-engineered analogue control systems might please engineers, but they go wrong quite often. Why not, instead, bolt the gyros and the accelerometers to the floor instead of trying to keep them level? You can then sort out the directions in 3 planes by complicated computing. That way, all you get is a lot of little 1s and 0s rushing about in a computer processor which is a virtual model of which way is up, instead of the real thing.
IRS isn't 'better' than GPS. GPS is acually more acurate - most of the time! However, it has a different type of reliability. If you have 2, or even better, 3 IRSs on board and you have a system of cross-checking, as each one is totally independent, it's very unlikely that all of them will be wrong to put you in precisely the same (wrong) place. GPS isn't like that. When it's good, it's very very good. But if it's wrong all of your GPS receivers will be the same amount wrong, so you'll never spot the problem. More importantly, on a bad day, you just might not be able to get a sufficiently reliable GPS signal for the thing to work at all.
And don't forget the bottom line. On a bad day, the US Government might just decide to switch GPS off for political or military reasons. Even though one hopes that that's pretty unlikely, the world is an uncertain place and you can never be sure. However, no-one can switch IRS/FMS off. It is totally self-contained within the aircraft. It depends on no-one.
Last edited by oxford blue; 16th Oct 2002 at 21:22.
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Q Feel Clarification
To clarify t.o.'s post...
Q feel is an artifical feel system which is made to be proportional (or at least dependent upon) dynamic (or more properly kinetic) pressure, typically denoted as 'q', hence q-feel.
Therefore one must rely on something more sophisticated than springs - the traditional way would have used some form of bellows arrangement, providing a direct 'q' input from a pitot-static source. The more modern way might be to use actuation of some form either as a direct force system or to mechanise a lever system to provide varying mechanical advantage over a fixed spring.
The advantage of q-feel is that it restores the control forces to a proportionality with the airspeed, in a similar manner to a manual system, and therefore the force feedback to the pilot is roughly proportional to the effect of the controls.
(1 deg of elevator at 300kts will create roughly 9 times the pitching moment as 1 degree at 100 kts; the pilot should therefore have to pull 9 times harder to obtain that 1 degree of elevator, in order for the relationship between pilot force and aircraft response to be similar at both speeds. q-feel provides the means to generate that force multiple.)
Note that a clever mechanical system designer can do away with q-feel and provide similar feel harmony to the pilot by means of carefully chosen system non-linearity using only "springs" and levers. But there is inevitably more of a design compromise involved; you get what you pay for.
Q feel is an artifical feel system which is made to be proportional (or at least dependent upon) dynamic (or more properly kinetic) pressure, typically denoted as 'q', hence q-feel.
Therefore one must rely on something more sophisticated than springs - the traditional way would have used some form of bellows arrangement, providing a direct 'q' input from a pitot-static source. The more modern way might be to use actuation of some form either as a direct force system or to mechanise a lever system to provide varying mechanical advantage over a fixed spring.
The advantage of q-feel is that it restores the control forces to a proportionality with the airspeed, in a similar manner to a manual system, and therefore the force feedback to the pilot is roughly proportional to the effect of the controls.
(1 deg of elevator at 300kts will create roughly 9 times the pitching moment as 1 degree at 100 kts; the pilot should therefore have to pull 9 times harder to obtain that 1 degree of elevator, in order for the relationship between pilot force and aircraft response to be similar at both speeds. q-feel provides the means to generate that force multiple.)
Note that a clever mechanical system designer can do away with q-feel and provide similar feel harmony to the pilot by means of carefully chosen system non-linearity using only "springs" and levers. But there is inevitably more of a design compromise involved; you get what you pay for.
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7. Don't fly there. Get out of it as quickly as possible, if necessary by a 180 degree turn. Keep continuous ignition.
6. Braking distance is increased on a wet runway. V1 is the last point at which the take off can be aborted allowing the aircraft to remain on the runway. (Yes, I know there's lots of performance imprecision there, but let's keep this simple). So wet v1 is normally a lower speed than dry v1.
6. Braking distance is increased on a wet runway. V1 is the last point at which the take off can be aborted allowing the aircraft to remain on the runway. (Yes, I know there's lots of performance imprecision there, but let's keep this simple). So wet v1 is normally a lower speed than dry v1.
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Regarding nr.8
If a TOW is limited by an obstacle in 2nd segment, it means that the aircraft has to do better than the normal 2nd segment climb. If it is a twin then normally it needs to do 2.4% gradient after T/O if one engine fails. If there is an obstacle in the flight path it needs to clear that obstacle by 35' net gradient, and it means that it has to better than the above said 2.4%; otherwise it would not be an obstacle.
There are two ways of increasing the gradient: One is to make the airplane lighter for T/O, and than we are TOW limited for that obstacle. The other one is to increase the T/O speed, which is not always possible, first due to increased stopping distance in case of abort, and the other thing is due to the higher speed, more time is spent on the rwy and it in turn brings you closer to the obstacle you are trying to avoid in the first place.
Also by using a lesser flap setting for T/O increases the gradient but requiers a longer T/O run.
If a TOW is limited by an obstacle in 2nd segment, it means that the aircraft has to do better than the normal 2nd segment climb. If it is a twin then normally it needs to do 2.4% gradient after T/O if one engine fails. If there is an obstacle in the flight path it needs to clear that obstacle by 35' net gradient, and it means that it has to better than the above said 2.4%; otherwise it would not be an obstacle.
There are two ways of increasing the gradient: One is to make the airplane lighter for T/O, and than we are TOW limited for that obstacle. The other one is to increase the T/O speed, which is not always possible, first due to increased stopping distance in case of abort, and the other thing is due to the higher speed, more time is spent on the rwy and it in turn brings you closer to the obstacle you are trying to avoid in the first place.
Also by using a lesser flap setting for T/O increases the gradient but requiers a longer T/O run.
