CRJ V1 cuts !

Pilot Hopeful said:
May we explore this rotation issue further? Obviously, an unnatural yanking of the aircraft off the ground is undesirable, regardless of engine failure. And as several posts have noted here, stabilizing yaw with the assistance of visual cues is helpful before climbing into the clouds.

However, aircraft performance calculations are based on the aircraft rotating at Vr. On the CRJ, that speed is often very near or at V1. I would argue that it is nearly impossible NOT to be in the rotation as the aircraft begins the yaw towards the failed engine if we are flying the profile as specified, which requires rotating at Vr, not some arbitrary higher speed.

Sure, many airports offer plenty of margin, so being a little fast is probably not a problem in reality. But I would also argue that not rotating at the specified rotation rate at Vr is similar to deciding to discontinue a takeoff above V1; both scenarios invalidate planned data and could compromise (or eliminate) safety margins (including obstacle clearance on the climb).

So, the lessons here seem to be:
(1) Fly the profile.
(2) Rotate at Vr, but don't over-rotate or accelerate the rotation rate.
(3) Concentrate on maintaining directional control, especially while visual references are present.

Does that sound correct?
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Depends what you use for performance. Generic aircraft data is predicated of DER@35 feet, APg/ARinc back the profile back to rotation point. On runways longer than TORA/TODA requirements, depending on dataset you may have free runway available, or not.
 
Autothrust Blue said:
It's a good point, but aircraft control is primary. Once OP gets the stop-the-yaw part down, then we can finesse the rotation-at-Vr part. Rotation at Vr does you no good if there's an ensuing snaproll and sound of bagpipes.
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Next Gen Airbus rumored to be installing Auto Bagpipes as standard equipage. ;)
 
Autothrust Blue said:
One thing that I don't like about my employer's procedures, incidentally, is that a deceleration to V2, if the engine quits above V2, is called for; I'd rather be V2 ≤ airspeed ≤ V2+10 KIAS than try to decelerate to exactly V2, obstacle clearance notwithstanding. (Our normal two-engine climbout is
"minimum" V2+20, so if you "fly the profile" you'll find yourself well through V2 anyway when one dies at 400'.)

#annoyed
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Raises a question I brought up at my last recurrent. What is the best angle of climb speed in your jet? I'm pretty damned sure it's rarely if ever V2 in most jets. So then, what is V2? I think V2 is an accepted, named number that is used for standardization purposes -standardization of pilot technique and written procedures- rather than a number that denotes optimized performance. It's the target speed to keep everyone on the same page from the perspective of writing documentation. It's also the lowest speed at which the standardized climb performance can be maintained, but could the climb performance be better at a faster speed? So V2 strikes me as being akin to standard temperature. That's a named number for standardization purposes. We all use it, yet it doesn't really mean anything beyond its purpose as a standard.
I asked a bunch of instructors about this when I was at training but none had any solid answer, and all were left sort of scratching their noggins over the question. Anyone here have any info or hypotheses?
 
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Crop Duster said:
Raises a question I brought up at my last recurrent. What is the best angle of climb in your jet? I'm pretty damned sure it's not V2 in most jets. So then, what is V2? I think V2 is an accepted, named number that is used for standardization purposes -standardization of pilot technique and written procedures- rather than a number that denotes optimized performance. It's the lowest speed at which the climb performance can be maintained, but could the climb performance be better at a faster speed? So V2 strikes me as being akin to standard temperature. That's a named number for standardization purposes. We all use it, yet it doesn't really mean anything beyond its purpose as a standard.
I asked a bunch of instructors about this when I was at training but none had any solid answer, and all were left sort of scratching their noggins over the question. Anyone here have any info or hypotheses?
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Your jet is certified under pt25, and may not have published best angle/best rate speeds, and it's not really relative.

V2 is your second segment speed, which will meet or exceed the minimum climb gradient. (Unless you depart overweight) It's valid from departure airport elevation until a minimum of 400 feet above the departure airport (usually up to 1500 feet depending on manufacturer) only in the specified configuration for your plane.

It's not an accepted number, then name (V2) is in their terms and glossary of the FAR and your AFM. Second segment is part of the departure profile.


A 4 or 5 segment departure is not the same thing as Vxse and Vyse from piston flying, and doesn't really relate.
 
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TUCKnTRUCK said:
Your jet is certified under pt25, and may not have published best angle/best rate speeds, and it's not really relative.

V2 is your second segment speed, which will meet or exceed the minimum climb gradient. (Unless you depart overweight) It's valid from departure airport elevation until a minimum of 400 feet above the departure airport (usually up to 1500 feet depending on manufacturer) only in the specified configuration for your plane.

It's not an accepted number, then name (V2) is in their terms and glossary of the FAR and your AFM. Second segment is part of the departure profile.


A 4 or 5 segment departure is not the same thing as Vxse and Vyse from piston flying, and doesn't really relate.
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Oh, I get all that. The question I want to know is what is the single engine best angle of climb speed for a given situation? I'm pretty sure it's not V2. I'm not an aerodynamic engineer, but there's got to be a way to calculate it. Until I've cleared the rocks, I'd rather be flying at best climb gradient speed than any other speed. V2 is good enough for the published procedures, but I doubt it's optimal. That said, I'm not suggesting flying at other than V2... This is just an academic question at this point.
 
Crop Duster said:
Raises a question I brought up at my last recurrent. What is the best angle of climb speed in your jet? I'm pretty damned sure it's rarely if ever V2 in most jets. So then, what is V2? I think V2 is an accepted, named number that is used for standardization purposes -standardization of pilot technique and written procedures- rather than a number that denotes optimized performance. It's the target speed to keep everyone on the same page from the perspective of writing documentation. It's also the lowest speed at which the standardized climb performance can be maintained, but could the climb performance be better at a faster speed? So V2 strikes me as being akin to standard temperature. That's a named number for standardization purposes. We all use it, yet it doesn't really mean anything beyond its purpose as a standard.
I asked a bunch of instructors about this when I was at training but none had any solid answer, and all were left sort of scratching their noggins over the question. Anyone here have any info or hypotheses?
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Best rate in the E-jet was roughly Vfs+50 if memory serves, but we didn't ever fly that airspeed. I can dig out Fly the Wing, but generally you're going to go 250 clean below 10 and then either an FMC or ECON speed or a fixed climb profile speed above. (290/.70 works well enough in the Deuce.) There's more to an efficient climb than merely best rate in a jet.

Have a look at Airbus's Getting to Grips with Aircraft Performance. V2 is computed based upon many things, including Vstall and Vmca in the takeoff configuration.
 
Autothrust Blue said:
Best rate in the E-jet was roughly Vfs+50 if memory serves, but we didn't ever fly that airspeed. I can dig out Fly the Wing, but generally you're going to go 250 clean below 10 and then either an FMC or ECON speed or a fixed climb profile speed above. (290/.70 works well enough in the Deuce.) There's more to an efficient climb than merely best rate in a jet.

Have a look at Airbus's Getting to Grips with Aircraft Performance. V2 is computed based upon many things, including Vstall and Vmca in the takeoff configuration.
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Yup, that's the swag I recall for Best RATE too. I'm after best ANGLE. That speed at which you are the most meters UP vs the most meters LAT. You know, to get you away from the ground in the shortest distance from the airport... which is nice in a place like, say, Aspen. I guess, without getting all hung up in the V2 issue, all I'm saying is that there is likely a speed that will do this better than V2. I''m asking, 1. Is that true? and 2. If so, what is that speed (and how calculated)?
And, again, I'm not suggesting flying other than one's profile, just wondering academically.
 
Crop Duster said:
Oh, I get all that. The question I want to know is what is the single engine best angle of climb speed for a given situation? I'm pretty sure it's not V2. I'm not an aerodynamic engineer, but there's got to be a way to calculate it. Until I've cleared the rocks, I'd rather be flying at best climb gradient speed than any other speed. V2 is good enough for the published procedures, but I doubt it's optimal. That said, I'm not suggesting flying at other than V2... This is just an academic question at this point.
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Code7700 has a solid article on the subject, the reality for a turbo Juliet though is that it's generally not necessary information so it's not tested nor provided.

Generally speaking between v2 and v1 there is minimal change in either rate or distance, as you slow beyond that point approaching Vs you'll likely end up with a negative gradient.

If you have free time at your next sim try climbing at v2 to 1500, then rewind and climb at v1. You'll find almost no change in time, distance or rate.
 
TUCKnTRUCK said:
Code7700 has a solid article on the subject, the reality for a turbo Juliet though is that it's generally not necessary information so it's not tested nor provided.
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Cool. Do you have a link?
Totally understood on the "NR" info statement. Like I said, just curious; Trying to understand it more fully. I'm one of those strange agents who likes to ask Why? and Wherefore? :)
 
TUCKnTRUCK said:
I posted an edit in the middle, seems like 770 is down, but here's a repost in the Q/A

http://aviation.stackexchange.com/q...um-angle-of-climb-be-achieved-for-jet-and-pro
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Thank you! :)
And as long as we are on the subject of weird deltas in airplane speeds....
Does anyone have any idea WHY turbine powered aircraft have no Vno (Max Structural Cruising Speed), or yellow arc on their ASIs?? Never have been able to get a definitive on this... It's not just Jets, it turbines. When you convert a piston to a turbine, the ASI gets swapped. Weird.
 
Crop Duster said:
And as long as we are the subject of weird deltas in airplane speeds....
Does anyone have any idea WHY turbine powered aircraft have no Vno (Max Structural Cruising Speed), or yellow arc on their ASIs?? Never have been able to get a definitive on this... It's not just Jets, it turbines. When you convert a piston to a turbine, the ASI gets swapped. Weird.
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14 CFR 25.1517 and 1303. :).

Intentionally vague? Who knows.
 
TUCKnTRUCK said:
14 CFR 25.1517 :).

Intentionally vague? Who knows.
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Vra is designed to prevent overspeed annunciation in turbulence and maintain speed within coffin corner. Vno is to prevent structural damage based on turbulence. I can understand part 25 A/C having different numbers due to differences in definitions and build strengths, etc., but I'm pretty sure this is not a part 25 issue. It affects part 23 aircraft. It seems to be based on engines pumping up and down or spinning on an axel.
Another way of thinking about is to accept that both Vra/Mra and Vno are max turbulence penetration speeds. Ok, fine, different regs; different names. I can accept that. But what remains weird is that turbulence penetration is largely based on structural strength. When you convert an aircraft from piston to turbine, you are not really changing structural strength, yet the speed changes! (I do understand that some structural mods can be made, like different engine mounts, etc, but the basic airframe in most cases remains the same.)
 
Crop Duster said:
Vra is designed to prevent overspeed annunciation in turbulence and maintain speed within coffin corner. Vno is to prevent structural damage based on turbulence. I can understand part 25 A/C having different numbers due to differences in definitions and build strengths, etc., but I'm pretty sure this is not a part 25 issue. It affects part 23 aircraft. It seems to be based on engines pumping up and down or spinning on an axel.
Another way of thinking about is to accept that both Vra/Mra and Vno are max turbulence penetration speeds. Ok, fine, different regs; different names. I can accept that. But what remains weird is that turbulence penetration is largely based on structural strength. When you convert an aircraft from piston to turbine, you are not really changing structural strength, yet the speed changes! (I do understand that some structural mods can be made, like different engine mounts, etc, but the basic airframe in most cases remains the same.)
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25.1517 (b) includes the rational investigation. Generally, turbulence penetration has not been found to cause g loading which exceeds g-load limitations of the airplane. Some planes like the hawker have a published speed for turbulence other don't.

It's not a required indication though, and given the variable nature for many airplanes isn't really needed- and would likely lead to many crews slowing unnecessarily.
 
TUCKnTRUCK said:
25.1517 (b) includes the rational investigation. Generally, turbulence penetration has not been found to cause g loading which exceeds g-load limitations of the airplane. Some planes like the hawker have a published speed for turbulence other don't.

It's not a required indication though, and given the variable nature for many airplanes isn't really needed- and would likely lead to many crews slowing unnecessarily.
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Yeah, like I said, V/Mra and Vno are different. I just posited the similarity for simplicity. There are definitely differences in build between part 25 and part 23 aircraft. That's not the issue. The question boils down to when you take a part 23 piston aircraft and convert it to a turbine on the same airframe*, why do the speeds change? It's the same airframe, certified to the original type specs. So that's not the reason for the loss of the yellow arc on the ASI. What is??

*examples would be taking a Cessna 210 (part 23 piston airplane) and converting it to a RR Turbine; taking a Beech Duke (part 23 piston airplane) and dropping in PT-6 engines. In both of these cases, when the engines change, the ASI changes (you lose the yellow arc and Vno) but there is no change to the airframe.
 
Crop Duster said:
Yeah, like I said, V/Mra and Vno are different. I just posited the similarity for simplicity. There are definitely differences in build between part 25 and part 23 aircraft. That's not the issue. The question boils down to when you take a part 23 piston aircraft and convert it to a turbine on the same airframe*, why do the speeds change? It's the same airframe, certified to the original type specs. So that's not the reason for the loss of the yellow arc on the ASI. What is??

*examples would be taking a Cessna 210 (part 23 piston airplane) and converting it to a RR Turbine; taking a Beech Duke (part 23 piston airplane) and dropping in PT-6 engines. In both of these cases, when the engines change, the ASI changes (you lose the yellow arc and Vno) but there is no change to the airframe.
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It's not required on the ASI for turbine equipment, the only requirement is for a moving Vmo indicator if Vmo/Vne changes with altitude. (25.1303 and no idea what the applicable 23 chapter is). There is no requirement for the RA speed on the instrument. Dig into .335 / .341for design airspeeds, then compare that to part .23 requirements.

Generally speaking in most tribune equipment due to testing it's not a needed airspeed. Regarding adding a turbine to a piston airplane under .23 I have no idea - probably somewhere under recertification and testing requirements.
 
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Autothrust Blue said:
One thing that I don't like about my employer's procedures, incidentally, is that a deceleration to V2, if the engine quits above V2, is called for; I'd rather be V2 ≤ airspeed ≤ V2+10 KIAS than try to decelerate to exactly V2, obstacle clearance notwithstanding. (Our normal two-engine climbout is
"minimum" V2+20, so if you "fly the profile" you'll find yourself well through V2 anyway when one dies at 400'.)

#annoyed
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Guess your employer forgot about AA191. Granted, you're not flying a DC10, but that seems like a questionable policy regardless. It should be like you said to fly at whatever airspeed you have as long as it's at least V2 and less than V2+10, and decelerate to V2+10 if you're faster.
 
Hello again, can anyone recommend a resource for getting a better understanding of the CRJ Autopilot. The Pilot Resource Manual from the company just kind of lists it out as - these are the lateral modes, these are the vertical modes.

I've done dumb stuff like rolling the VS up to transition to less than a 1000 fpm after hitting ALTS CAP and didn't know how to get myself out of it (I guess hitting ALT would be one option in that situation) and accidentally kicking myself out of heading when going to green needles (forgot to hit HDG when in NAV on that one). So kind of looking for a practical users guide kind of thing if anyone knows of one - like, if you find yourself in this mode when you didn't want it, this is what you did wrong and what you should have done kind of thing..

Thanks again everyone, so much more helpful than the Angry Pilot Chat forum lol !
 
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