An interesting NOTAM?
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Depends on where you're flying, in the UK ATC can see your IAS through mode S. In Aus it's on the drawing board but we will have to wait for our radar heads to be upgraded to mode S, and for Eurocat to get an upgrade too. It's in the pipeline though.
Grandpa Aerotart
Ahhh - that makes sense - I will only have to be careful going in and out of LHR/Europe
We're always back at min clean by the time we are below 10 anyway at LHR - and generally on our way to Lambourne holding pattern.
We're always back at min clean by the time we are below 10 anyway at LHR - and generally on our way to Lambourne holding pattern.
Bloggs,
My dear chap, I have no idea what type of aircraft you are flying, or whether it even is something you have come across, but there are a number of aircraft on my license where the minimum clean speeds at hight weights are well above 250 knots, and not by one or 2 knots, either.
Are you really suggesting I should fly with flap out to 10,000'. The list of reasons why you shouldn't start with the fact that the allowable negative G with any flap out is zero, naught, nothing. Can you predict that there will be no turbulence of any kind, that might cause a problem, on every heavy departure??
That is why FAR 91.117(d) is there, to clearly authorize the PIC to operate the aircraft in accord with the AFM and other manufacturer's recommendation.
There is no such clear authorization in the Australian regulation, and there should be -- whether ATC or statutory speed limits are in force.
We did have it clearly laid out in our draft Part 91, it will be interesting to see if it survives, because it is vital to the pilots of every large aircraft.
Do you really want to be subjected to a situation where some chairborn ace can retrospectively question your operational safety decisions, to reinterpret your AFM, for an aircraft that, in all likelihood, they have no knowledge of, let alone experience.
The whole criticism of the Australian regulations is that they are so totally prescriptive and inflexible, and in an example like this, are counterproductive in safety terms.
The only reason Australian regulations do not cause more trouble than they do, is that they are seldom enforced, and only then, very selectively.
Tootle pip!!
PS: What make you think that FAA need to file a difference for Part 91.117(d), or put another way, what make you thing that the ICAO SARPs are so inflexible that a difference even exists.
For example, "FAA D", there is no such thing. FAA D is ICAO, and by notifying a difference for VFR weather minima, FAA remains ICAO compliant.
My dear chap, I have no idea what type of aircraft you are flying, or whether it even is something you have come across, but there are a number of aircraft on my license where the minimum clean speeds at hight weights are well above 250 knots, and not by one or 2 knots, either.
Are you really suggesting I should fly with flap out to 10,000'. The list of reasons why you shouldn't start with the fact that the allowable negative G with any flap out is zero, naught, nothing. Can you predict that there will be no turbulence of any kind, that might cause a problem, on every heavy departure??
That is why FAR 91.117(d) is there, to clearly authorize the PIC to operate the aircraft in accord with the AFM and other manufacturer's recommendation.
There is no such clear authorization in the Australian regulation, and there should be -- whether ATC or statutory speed limits are in force.
We did have it clearly laid out in our draft Part 91, it will be interesting to see if it survives, because it is vital to the pilots of every large aircraft.
Do you really want to be subjected to a situation where some chairborn ace can retrospectively question your operational safety decisions, to reinterpret your AFM, for an aircraft that, in all likelihood, they have no knowledge of, let alone experience.
The whole criticism of the Australian regulations is that they are so totally prescriptive and inflexible, and in an example like this, are counterproductive in safety terms.
The only reason Australian regulations do not cause more trouble than they do, is that they are seldom enforced, and only then, very selectively.
Tootle pip!!
PS: What make you think that FAA need to file a difference for Part 91.117(d), or put another way, what make you thing that the ICAO SARPs are so inflexible that a difference even exists.
For example, "FAA D", there is no such thing. FAA D is ICAO, and by notifying a difference for VFR weather minima, FAA remains ICAO compliant.
OS,
No, I'm just having a gay old time, being a bit sarcastic with Bloggs, who might or might not actually be a Captain, in the aeronautical sense, as opposed to the Bell Captain ( and I don't mean helicopters).
Tootle pip!!
No, I'm just having a gay old time, being a bit sarcastic with Bloggs, who might or might not actually be a Captain, in the aeronautical sense, as opposed to the Bell Captain ( and I don't mean helicopters).
Tootle pip!!
As for 145 kts at Hornsby
It would be achievable in many aircraft (744/767/777/A380 --- if not the big B737) but, boy will it be noisy, all the low noise continuous descent approaches out the window ---- I can hear the objections now.
Big increases in fuel bills too, but I guess the airlines will be happy, because it will be "so much safer".
Is this another April Fool joke somebody is playing in Dick?
Tootle pip!!
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Leadsled
A response post to your previous is here http://www.pprune.org/dg-p-reporting...ml#post5602380
It is relevant to the NAS discussion.
Cheers
A response post to your previous is here http://www.pprune.org/dg-p-reporting...ml#post5602380
It is relevant to the NAS discussion.
Cheers
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Easy Jaba. 201 KIAS. Only an irresponsible fellow would go over VNE.
Don't try that at home in the RV10 or you'll get that dreaded wing flutter I have been reading about.
Don't try that at home in the RV10 or you'll get that dreaded wing flutter I have been reading about.
So you have been reading about these things, good boy!
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And what's the problem with TAS exceeding an IAS Vne? Turboprops do that all the time in cruise let alone descent... I guess you guys don't have a barber pole for your high altitude jaunts!
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Flutter.......
Someone who knows more about the transport category aircraft design may have some interesting answers here, but there are quite a few articles around you can read about this topic.
Some gliders for example have a plaque with reduced VNE numbers at higher altitudes for this very reason. Its not about the density of air its all about velocity!
Back to normal viewing!
Someone who knows more about the transport category aircraft design may have some interesting answers here, but there are quite a few articles around you can read about this topic.
Some gliders for example have a plaque with reduced VNE numbers at higher altitudes for this very reason. Its not about the density of air its all about velocity!
Back to normal viewing!
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I'm a bit concerned about the mix of airspeed terms that people have been using. So with the risk of 'sucking eggs' this might be interesting/informative for some.
Yes, it is about velocity, but air density affects how we interpret our velocity (ie, what readings we are getting - or not getting - on the instruments in front of us).
The key determinator of aircraft performance is IAS. IAS is critical to the flight performance of the aircraft as it is related to dynamic pressure which is related to the amount of lift produced (Lift = CL x half rho V squared x S). Aerodynamically, IAS is what matters. Factors such as altitude other than standard sea level, errors of the instrument, errors of installation, compressibility etc may create great variations between the instrument indications and the actual flight speed.
CAS (Calibrated Air Speed) is the result of correcting IAS for errors of the instrument and position or location of installation (usually small).
EAS (Equivalent Air Speed) is the result of correcting CAS for compressibility effects. At high flight speeds the stagnation of pressure in the pitot tube is not representative of the airstream dynamic pressure.
TAS (True Airspeed) is the actual speed of the aircraft relative to the air. TAS results when EAS is corrected for density altitude. Temperature and altitude are the key players here. For a given IAS the TAS will increase with increasing altitude.
As the primary airspeed indicator in front of us usually displays IAS, limiting and operating airspeeds are usually published as IAS. SOME aircraft may publish a limiting TAS but I wouldn't say that is common.
Higher performance aircraft with large speed and altitude envelopes will publish speeds appropriate to altitude. Some have an air data computer which provides data to a handy little Vmo (barbers pole) needle which will show you the limiting IAS as it reduces with increased altitude. If you don't have that you will need to remember that the Vne on the instrument is that which applies at SEA LEVEL! Consult the manual for limits applicable at higher altitude. The RA-AUS website offers this suggestion if you don't have that data:
It is possible for a turboprop aircraft to have a Vne of say 240 KIAS (Sea Level value) and cruise in mid twenties altitude at about 160 KIAS while having a TAS of about say 260 knots (and a Ground Speed of 300 knots)! The barbers pole might be indicating say about 190 KIAS so the aircraft is comfortably cruising below max operating speed and yet above the stall - remember it is the INDICATED airspeed values we are interested in here. The higher you go, the smaller that margin becomes.
Some may have heard of the term 'coffin corner.' As an aircraft flies higher it will reach a point where the maximum operating speed and stall speed close to the point where the pilot may not be able to detect the difference between pre-stall buffet and high Mach number buffet. At the ABSOLUTE AERODYNAMIC CEILING of the aircraft these two values are coincident (actually the upper value is Vdf/Mdf - maximum demostrated flight diving speed; the highest speed demonstrated during certification - Vmo/Mmo is buffered below that).
Rambling ramble over!
Yes, it is about velocity, but air density affects how we interpret our velocity (ie, what readings we are getting - or not getting - on the instruments in front of us).
The key determinator of aircraft performance is IAS. IAS is critical to the flight performance of the aircraft as it is related to dynamic pressure which is related to the amount of lift produced (Lift = CL x half rho V squared x S). Aerodynamically, IAS is what matters. Factors such as altitude other than standard sea level, errors of the instrument, errors of installation, compressibility etc may create great variations between the instrument indications and the actual flight speed.
CAS (Calibrated Air Speed) is the result of correcting IAS for errors of the instrument and position or location of installation (usually small).
EAS (Equivalent Air Speed) is the result of correcting CAS for compressibility effects. At high flight speeds the stagnation of pressure in the pitot tube is not representative of the airstream dynamic pressure.
TAS (True Airspeed) is the actual speed of the aircraft relative to the air. TAS results when EAS is corrected for density altitude. Temperature and altitude are the key players here. For a given IAS the TAS will increase with increasing altitude.
As the primary airspeed indicator in front of us usually displays IAS, limiting and operating airspeeds are usually published as IAS. SOME aircraft may publish a limiting TAS but I wouldn't say that is common.
Higher performance aircraft with large speed and altitude envelopes will publish speeds appropriate to altitude. Some have an air data computer which provides data to a handy little Vmo (barbers pole) needle which will show you the limiting IAS as it reduces with increased altitude. If you don't have that you will need to remember that the Vne on the instrument is that which applies at SEA LEVEL! Consult the manual for limits applicable at higher altitude. The RA-AUS website offers this suggestion if you don't have that data:
If there is insufficient manufacturer's information available for the aircraft you fly — and you are uncertain about the appropriate Vne for an operating altitude — then multiply the density altitude, in thousands of feet, by a factor of 1.5 to get the percentage decrease to apply to the specified Vne to establish a safe Vne appropriate to the altitude. For example if density altitude is 8000 feet and specified Vne is 100 knots then 8[000] × 1.5 = 12%. Corrected Vne = 88% of 100 = 88 knots IAS/CAS.
Some may have heard of the term 'coffin corner.' As an aircraft flies higher it will reach a point where the maximum operating speed and stall speed close to the point where the pilot may not be able to detect the difference between pre-stall buffet and high Mach number buffet. At the ABSOLUTE AERODYNAMIC CEILING of the aircraft these two values are coincident (actually the upper value is Vdf/Mdf - maximum demostrated flight diving speed; the highest speed demonstrated during certification - Vmo/Mmo is buffered below that).
Rambling ramble over!
Last edited by Captain Nomad; 30th Mar 2010 at 14:46.
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Captain Nomad
Yes agree with what you have posted, but its what you have not posted that is of interest. I see the RAAus actually make reference to this also.
In your Boeing/Aibus/DHC etc.... the issues of flutter may be well addressed and the critical speed for flutter will most likely be outside your other oprating limits.
This is not always the case for GA aircraft/Gliders/LSA or ultralights.
now Flutter in control surfaces has far less to do with density as it does velocity, the number of air particles ripping over the wing is not the problem, with flutter its more about the rate at which they rip over the surface and in an upset once bits start flopping around and they don't stop
.
Just trust me, I'm an engineer
. Problem is my area of expertise is not where this discussion needs it to be.
Yes agree with what you have posted, but its what you have not posted that is of interest. I see the RAAus actually make reference to this also.
In your Boeing/Aibus/DHC etc.... the issues of flutter may be well addressed and the critical speed for flutter will most likely be outside your other oprating limits.
This is not always the case for GA aircraft/Gliders/LSA or ultralights.
now Flutter in control surfaces has far less to do with density as it does velocity, the number of air particles ripping over the wing is not the problem, with flutter its more about the rate at which they rip over the surface and in an upset once bits start flopping around and they don't stop
.Just trust me, I'm an engineer
. Problem is my area of expertise is not where this discussion needs it to be.Join Date: Jun 2001
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One can't help but wonder if it has something to do with not operating the aircraft appropriately. Vne is not the only consideration. Not knowing or operating the aircraft appropriately with regard to the correct Va speed for the aircraft weight and altitude for example. That kind of flutter would not be considered normal for normal operation and certification purposes. Of course another consideration with an ageing aircraft is also slop in linkages/unbalanced control surfaces etc which would induce flutter at much lower speeds than normal. That second vid looks like someone wanted to start playing test pilot - good luck to him...! 
Am I the only one who thinks that V tail flutter is footage from a model?
Folks,
I think history will record the first instance of flutter in the stab of a Twin Comanche was during the UK ARB flight tests for a UK C. of A. Date about 1962 or 63. All this happened withing the aeroplane's normal operating envelope --- ie: Not beyond Vne.
I saw the aircraft after the incident, that the aircraft got back on the ground was a testament to the skill of the pilot, the CP of Air Couriers, the then Piper agents in UK.
As a result of the flutter, one side of the stab, from about the outer end of the servo tab, at an angle inboard to the leading edge at about a third semi-span had almost sheared off, and on the ground, part was folded back over the stab. After that, all Twin Comanches had an AD to strengthen the area, later incorporated in production.
The same pilot also survived a crash in a Apache, going around on one with gear and some flap out. You could see the aircraft shape where it went through the roof of an old barn on the extended centreline of RW 11 at Biggin Hill, coming to rest in the paddock just beyond the barn. Just as well all the roof timbers were about 300 years old. Both pilot and student only had cuts and scratches and bruises, not enough to avoid having to shout the bar that evening.
Tootle pip!!
PS: Loved the video, who did the animation. In the real case detailed above, the frequency of the flutter was estimated (from memory) to be 200-400cps.--- a "real buzz".
I think history will record the first instance of flutter in the stab of a Twin Comanche was during the UK ARB flight tests for a UK C. of A. Date about 1962 or 63. All this happened withing the aeroplane's normal operating envelope --- ie: Not beyond Vne.
I saw the aircraft after the incident, that the aircraft got back on the ground was a testament to the skill of the pilot, the CP of Air Couriers, the then Piper agents in UK.
As a result of the flutter, one side of the stab, from about the outer end of the servo tab, at an angle inboard to the leading edge at about a third semi-span had almost sheared off, and on the ground, part was folded back over the stab. After that, all Twin Comanches had an AD to strengthen the area, later incorporated in production.
The same pilot also survived a crash in a Apache, going around on one with gear and some flap out. You could see the aircraft shape where it went through the roof of an old barn on the extended centreline of RW 11 at Biggin Hill, coming to rest in the paddock just beyond the barn. Just as well all the roof timbers were about 300 years old. Both pilot and student only had cuts and scratches and bruises, not enough to avoid having to shout the bar that evening.
Tootle pip!!
PS: Loved the video, who did the animation. In the real case detailed above, the frequency of the flutter was estimated (from memory) to be 200-400cps.--- a "real buzz".
Check Attitude
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Point taken on the date of the Notam, yes it’s AM on 1st April, so it can qualify as an April Fool’s joke.
Notwithstanding that, there are many of the cosseted inept drawing significant government salaries who are quite capable of generating such a Notam.
Research the “Below 10,000 ft in controlled airspace” rules in Australia and many other countries.
In all cases the 250 kts is 250 KIAS, i.e. indicated airspeed.
The intent of the 250 KIAS is similar to the use of QNH below 10,000 ft, it establishes a common point of reference or datum to all aircraft below 10,000 ft.
250 kts IAS at sea level is near enough to 250 kts True Air Speed (and 250 kts Ground Speed with Nil wind).
Now look at 250 KIAS at 10,000 ft with, for our Northern region, a typical temperature of +10 degrees C.
A quick play with the whiz wheel will convert this to 287 kts TAS. Busted ?
Now add a 30 kt tailwind, and now would paint as 317 Kts Ground Speed !
Busted again ?
Radar, ADS B and other surveillance methods see ground speed, or rate of closure, not indicated or true air speed.
If this was an April Fool’s joke, lets laugh about it.
If not, what can be done about steering some common sense toward the authors?
Its their trainset.
Notwithstanding that, there are many of the cosseted inept drawing significant government salaries who are quite capable of generating such a Notam.
Research the “Below 10,000 ft in controlled airspace” rules in Australia and many other countries.
In all cases the 250 kts is 250 KIAS, i.e. indicated airspeed.
The intent of the 250 KIAS is similar to the use of QNH below 10,000 ft, it establishes a common point of reference or datum to all aircraft below 10,000 ft.
250 kts IAS at sea level is near enough to 250 kts True Air Speed (and 250 kts Ground Speed with Nil wind).
Now look at 250 KIAS at 10,000 ft with, for our Northern region, a typical temperature of +10 degrees C.
A quick play with the whiz wheel will convert this to 287 kts TAS. Busted ?
Now add a 30 kt tailwind, and now would paint as 317 Kts Ground Speed !
Busted again ?
Radar, ADS B and other surveillance methods see ground speed, or rate of closure, not indicated or true air speed.
If this was an April Fool’s joke, lets laugh about it.
If not, what can be done about steering some common sense toward the authors?
Its their trainset.
