1st Interview Q's
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studi
Sorry I can't help you with the .jpg images here. First they have to go to a host site and from there they can be linked to PPRuNe.
If you know someone with their own web page you have got it cracked!
If you know someone with their own web page you have got it cracked!
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betaboy
the chord is definitely the width of the blade and surely the point is to keep blade tip speed to a minimum and definitely subsonic.his advantages are however valid.
could anyone resolve a conundrum for me,i cannot get my head around the question in bristow page 2 what is the effect of weight on rate of descent and the apparent contradictory answer to question on page 18,how does weight affect an aircrafts flight profile descent point?
surely if the heavier aircraft has a greater rate of descent would it not require a later descent point,not an earlier one.
maybe the answer is there,but i have been mulling over it so long that i have confounded myself.
any help appreciated.
could anyone resolve a conundrum for me,i cannot get my head around the question in bristow page 2 what is the effect of weight on rate of descent and the apparent contradictory answer to question on page 18,how does weight affect an aircrafts flight profile descent point?
surely if the heavier aircraft has a greater rate of descent would it not require a later descent point,not an earlier one.
maybe the answer is there,but i have been mulling over it so long that i have confounded myself.
any help appreciated.
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Descent Point and Weight
Yes, agreed, Bristow's "check the momentum" explanation is next to useless. However, I know this effect is true. The machine I fly is very sensitive to this; you have to start a barber pole descent much earlier if you're heavier.
I've perused and searched the Tech Log, and have carefully poured through about 4 aerodynamics texts (Kermode, Dole, Naval Av, etc.), and have not found a definitive answer. I found a plausible explanation in an old (borrowed) internal Air Canada document on fuel efficiency: "higher landing weights will increase the descent distance for the SAME descent speed since it takes longer to dissipate the greater potential energy."
Also, lots of confusing discussion at:
http://www.pprune.org/forums/showthr...hreadid=129617
where the concensus seems to be that that the heavier a/c would be flying closer to Vmd (min drag speed).
And, a somewhat believable explanation from Bellerophon at:
http://www.pprune.org/forums/showthr...hreadid=125401
I'd be really happy if someone could point me to a definitive reference on this.
A heavier a/c will descent faster if you DON'T fix the airspeed. I.e. fix the AOA, and the heavier aircraft will descent at a higher airspeed, leading a higher descent rate.
--------------------------------------------
Also, a link to a picture re. the excess thrust discussion above:
http://history.nasa.gov/SP-367/f119.htm
I've perused and searched the Tech Log, and have carefully poured through about 4 aerodynamics texts (Kermode, Dole, Naval Av, etc.), and have not found a definitive answer. I found a plausible explanation in an old (borrowed) internal Air Canada document on fuel efficiency: "higher landing weights will increase the descent distance for the SAME descent speed since it takes longer to dissipate the greater potential energy."
Also, lots of confusing discussion at:
http://www.pprune.org/forums/showthr...hreadid=129617
where the concensus seems to be that that the heavier a/c would be flying closer to Vmd (min drag speed).
And, a somewhat believable explanation from Bellerophon at:
http://www.pprune.org/forums/showthr...hreadid=125401
I'd be really happy if someone could point me to a definitive reference on this.
A heavier a/c will descent faster if you DON'T fix the airspeed. I.e. fix the AOA, and the heavier aircraft will descent at a higher airspeed, leading a higher descent rate.
--------------------------------------------
Also, a link to a picture re. the excess thrust discussion above:
http://history.nasa.gov/SP-367/f119.htm
Last edited by betaboy; 6th Oct 2004 at 06:41.
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Greeetings Gents,
It is my understanding that for a given speed in descent the heavier a/c will descend at a higher rate. Conversely for a given rate of descent the heavier a/c will descend at a faster speed. As top of descent point is based on ground speed the heavier you are the faster you'll go hence the earlier you must start to descend.
This is my take on that. So it's only worth the paper that it's printed on. Hope it helps though.
It is my understanding that for a given speed in descent the heavier a/c will descend at a higher rate. Conversely for a given rate of descent the heavier a/c will descend at a faster speed. As top of descent point is based on ground speed the heavier you are the faster you'll go hence the earlier you must start to descend.
This is my take on that. So it's only worth the paper that it's printed on. Hope it helps though.
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Hi Guys
After both doing the interviews (1st) and reading the books xyz, abc and ace, my tips.
Use the questions as an aid to research, there are mistakes in all three.
Remember that it is just required knowledge and the point of the interview is to recruit pilots for cathay not necessarily aeronautical engineers! So have a good think about the rest of it as well.
Good luck
After both doing the interviews (1st) and reading the books xyz, abc and ace, my tips.
Use the questions as an aid to research, there are mistakes in all three.
Remember that it is just required knowledge and the point of the interview is to recruit pilots for cathay not necessarily aeronautical engineers! So have a good think about the rest of it as well.
Good luck
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Smokie,
Bristow is right about critical engine on x-wind. It should be the downwind because if you lose it(downwind eng.) the upwind engine is going to aggravate the yaw.
Bristow is right about critical engine on x-wind. It should be the downwind because if you lose it(downwind eng.) the upwind engine is going to aggravate the yaw.
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Medwin:
No, not again...
If you consider giving "Bristow answers" at an interview - do a search here about the book first!
Bristow is right about critical engine on x-wind. It should be the downwind because if you lose it(downwind eng.) the upwind engine is going to aggravate the yaw.
If you consider giving "Bristow answers" at an interview - do a search here about the book first!
INTENTIONALLY LEFT BLANK
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On T/O the outboard Upwind engine will be the critical engine.
ie normally the aircraft will weathercock in to wind and you apply appropriate rudder to maintain centreline. If the upwind engine fails, due to the assymetry, you would have to put MORE rudder input, aggravating the situation.
ie normally the aircraft will weathercock in to wind and you apply appropriate rudder to maintain centreline. If the upwind engine fails, due to the assymetry, you would have to put MORE rudder input, aggravating the situation.
