Envoy CRJ700 climb airspeed

ATN_Pilot said:
I've got thousands, and I agree with him. Pilots love to say "it likes to climb fast" because pilots prefer to climb fast, but it just ain't so. Your anecdotal data after relatively few hours in the airplane are not giving you proper perspective. You tell someone to climb at 250 one flight and 310 the next, but what are the weights and atmospheric conditions? How are you controlling these variables to get proper comparisons? If I climb out at 310 leaving MSP in winter at a GTOW of 39,000 lbs, yes, I'm probably going to get better climb performance than climbing out of CUN at 55,000 lbs at 280 knots. Not because "it likes to climb fast," but because the variables have changed. I promise you, the plane does not "like to climb fast."
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My experiences say otherwise. Maybe I'm wrong. But from what I've seen, I stand by it, for now. I've got about 1k hours in the CRJ now (been almost 2 years here). I'm not super experienced yet, but I'd say I have a pretty good handle on it now.
 
mshunter said:
How so? Fuel burns drop at altitude, correct? So get up, and save gas? I'm always up for a little learning.
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Are you really, or are you just going to dismiss what people say? Because when you say that you're going by your experiences instead of by the physics, it sounds a lot like "my child got a vaccine, my child is autistic, therefore vaccines cause autism."

First, you aren't getting up to altitude quicker by climbing at a higher airspeed. I know that you think you are, but you aren't. Because physics. You are not, under any circumstances, going to get up to altitude more quickly by climbing at a speed higher than Vy.

Second, airliner economics are a balancing act, not just pinned to fuel burn. The variables include crew costs, maintenance costs, power-by-hour costs, fuel costs, etc. Airlines use a cost index (CI) to balance all of these variables, and they typically have engineers and accountants go over them on a periodic basis. I hear that some airlines even have dynamic CI calculators in dispatch that adjust the CI on a per-flight basis to squeeze every last penny of efficiency out. So if you ignore the CI number, you are not being the most efficient that you can be, because you aren't factoring in all of the variables that were used to determine that CI. Perhaps the power-by-hour costs are outweighing the fuel savings that you think you are getting, for example. You have no way of knowing. Fly the CI.
 
ATN_Pilot said:
Are you really, or are you just going to dismiss what people say? Because when you say that you're going by your experiences instead of by the physics, it sounds a lot like "my child got a vaccine, my child is autistic, therefore vaccines cause autism."

First, you aren't getting up to altitude quicker by climbing at a higher airspeed. I know that you think you are, but you aren't. Because physics. You are not, under any circumstances, going to get up to altitude more quickly by climbing at a speed higher than Vy.

Second, airliner economics are a balancing act, not just pinned to fuel burn. The variables include crew costs, maintenance costs, power-by-hour costs, fuel costs, etc. Airlines use a cost index (CI) to balance all of these variables, and they typically have engineers and accountants go over them on a periodic basis. I hear that some airlines even have dynamic CI calculators in dispatch that adjust the CI on a per-flight basis to squeeze every last penny of efficiency out. So if you ignore the CI number, you are not being the most efficient that you can be, because you aren't factoring in all of the variables that were used to determine that CI. Perhaps the power-by-hour costs are outweighing the fuel savings that you think you are getting, for example. You have no way of knowing. Fly the CI.
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Thanks. I'm being serious. And what I'm saying, is that I've noticed at higher airspeed I've consistently seen higher climb rates. So I'm my mind, I'm getting to altitude sooner, due to the higher rate of climb. But now that we have "Smart CI," none of that matters to me anymore. So far, in this thread I've seen a lot of people talk about "book numbers." I've yet to see those numbers. I have looked through my company provided numbers, and the manufacturer numbers in their own manuals. Not even a chart for me to reference.
 
You don't have a chart for LDmax? Odd. I'm pretty sure we had one in the Pinnacle books.

Ignore what you think you've seen. You are being deceived by anecdotal evidence without weighing all of the variables. If memory serves, Vy is usually below 250 in the CRJ, actually. It's nowhere close to 300.
 
BobDDuck said:
Yes fuel burn drops with altitude, bit that would mean you want to fly best rate to get there quickly and no LDmax chart has best rate all the way to the right.
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yeah_science_breaking_bad.gif
 
ATN_Pilot said:
You don't have a chart for LDmax? Odd. I'm pretty sure we had one in the Pinnacle books.

Ignore what you think you've seen. You are being deceived by anecdotal evidence without weighing all of the variables. If memory serves, Vy is usually below 250 in the CRJ, actually. It's nowhere close to 300.
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We don't have that chart...just kind of assumed that was covered in private/commercial training.
 
BobDDuck said:
Yes fuel burn drops with altitude, bit that would mean you want to fly best rate to get there quickly and no LDmax chart has best rate all the way to the right.
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​
ATN_Pilot said:
You don't have a chart for LDmax? Odd. I'm pretty sure we had one in the Pinnacle books.

Ignore what you think you've seen. You are being deceived by anecdotal evidence without weighing all of the variables. If memory serves, Vy is usually below 250 in the CRJ, actually. It's nowhere close to 300.
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Hmm. Like I said in an earlier post, I reference this stuff a lot for questions I have, so I'll post this as to where I'm getting my info from. Am I interpreting it wrong? And because of what I read here, I have to admit, I didn't look for an LDmax chart. I'll have a look through again and see if I find one. What leads me to believe that it's not necessarily L>D max is what is written here.


Factors affecting the rate of climb
The rate of climb is the vertical component of the speed, expressed in feet per minute. It depends on the airspeed (V) and the angle of climb. Using the same logic as for the climb gradient:
Rate of climb = V x sin (α) = V x Climb gradient = V x (Thrust – Drag) / Weight

Speed and acceleration
For a given aircraft mass the maximum rate of climb will occur when the product of the speed and the excess thrust is greatest. As both thrust and drag vary with speed, there will be a particular speed at which this occurs (the best rate of climb speed) that is different from the best angle of climb speed. If the speed is increased above that for the best angle of climb although the climb angle will decrease, the rate of climb will initially increase.
If the aircraft is required to fly at different speed, the rate of climb will be reduced.
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http://www.skybrary.aero/index.php/...Aircraft_Performance_During_Takeoff_and_Climb

I also reference Aerodynamics for Naval Aviators quite a bit. Here is an excerpt from it. If it's hard to read like that (copy paste comes out funny and drops out parts and pieces) you can click the link and head to page 154 (type page 172 for the page in a PDF reader). I read this as a higher velocity will give you a faster rate of climb for the same angle, L/D max only plays a small role in something with as much power as we have (which honestly isn't saying much). It also references that best angle would be an L/D max climb in the previous few pages.

http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80t-80.pdf


​
Of greater general interest in climb performance
are the factors which affect the rate of
climb. The vertical velocity of an airplane
depends on the flight speed and the inclination
of the flight path. In fact, the rate of climb
is the vertical component of the flight path
velocity. By the diagram of figure 2.21, the
following relationship is developed:
since
RC- 101.3 V sin y

then
RC=101.3 V
a&
with Pa=%2 -v
and Pr=&
where
RC=rate of climb, f.p.-.
P11=power available, h.p.
Pr=power re
W=weight, 1%
uired, h.p.
s
and
V=true airspeed, knots
33,000 is the factor converting horsepower
to ft-lbs/min
101.3isthefactorconvertingknocstof.p.m.
The above relationship states that, for a given
weight airplane, the rate af climb (RC) depends

on the difference between the power available
and the power required (Pd- Pr), or excess

power. Of course, when the excess power is
zero (Pa-Pr=O or Pa== PI), the rate of climb
is zero and the airplane is in steady level flight.
When the power available is greater than the
power required, the excess power will, allow a
rate of climb specific to the magnitude of excess
power. Also, when the power available is
less than the power required, the deficiency of
power produces a rate of descent. This relationship
provides the basis for an important
axiom of flight technique: “For the conditions
of steady flight, the power setting is the primary
control of rate of climb or descent”.
One of the most important items of climb
performance is the maximum rate of climb.
By the previous equation for rate of climb,
maximum rate of climb would occur where
there exists the greatest difference between
power available and power required, i.e.,
maximum (Pa- Pr). Figure 2.21 illustrates
the climb rate performance with the curves of
power available and power required versus
velocity. The power required curve is again a
representative airplane which could be powered
by either a turbojet or propeller type powerplant.
The power available curves included
are for a characteristic propeller powerplant
and jet powerplant operating at maximum
output.
The power curves for the representative propeller
aircraft show a variation of propulsive
power typical of a reciprocating engine-propeller
combination. The maximum rate of
climb for this aircraft will occur at some speed
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​
 
We used to climb out in "climb 2" to save gas, but the company crunched the numbers and realized that the extra time at lower altitude was burning more gas than the fuel savings of being at a lower power setting. So now we go to "climb 1" as soon as we get cleaned up. It is a higher power setting, but we get to altitude quicker.

At any rate, it's what the company tells us to do, so we do it.
 
Screaming_Emu said:
Hooray, let's go really fast so we can burn a crap ton more gas and get there three mins early!
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Exactly. I always find it humorous flying with some commuters and standup crews... They get COMPLETELY bent out of shape about getting slowed to 190 on downwind or some such thing. It gets you in like, what... 5 secs slower? Relax and most importantly, quit whining. The time of arrival was pretty much decided on the ground just before we took off. Seriously, it's amazing how many pilots are bad at basic math.
 
GypsyPilot said:
Exactly. I always find it humorous flying with some commuters and standup crews... They get COMPLETELY bent out of shape about getting slowed to 190 on downwind or some such thing. It gets you in like, what... 5 secs slower? Relax and most importantly, quit whining. The time of arrival was pretty much decided on the ground just before we took off. Seriously, it's amazing how many pilots are bad at basic math.
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Eh, when I flew standups, I wanted every extra second I could get. Didn't care how much extra fuel I burned. The company knew it was rampant with the standup crews, and they didn't care. It was just assumed that we were flying right up to the clacker on every single leg.
 
mshunter said:
Hmm. Like I said in an earlier post, I reference this stuff a lot for questions I have, so I'll post this as to where I'm getting my info from. Am I interpreting it wrong? And because of what I read here, I have to admit, I didn't look for an LDmax chart. I'll have a look through again and see if I find one. What leads me to believe that it's not necessarily L>D max is what is written here.

http://www.skybrary.aero/index.php/...Aircraft_Performance_During_Takeoff_and_Climb

I also reference Aerodynamics for Naval Aviators quite a bit. Here is an excerpt from it. If it's hard to read like that (copy paste comes out funny and drops out parts and pieces) you can click the link and head to page 154 (type page 172 for the page in a PDF reader). I read this as a higher velocity will give you a faster rate of climb for the same angle, L/D max only plays a small role in something with as much power as we have (which honestly isn't saying much). It also references that best angle would be an L/D max climb in the previous few pages.

http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80t-80.pdf
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You seem to just be misinterpreting, because those excerpts are supporting our arguments, not yours. Yes, for a given angle, extra speed results in increased climb rate. But you don't have infinite excess thrust, so you don't maintain the same angle as airspeed increases. As you increase airspeed, the angle decreases. By climbing at the best rate of climb speed, you are matching the optimum angle with the amount of excess thrust that you have.
 
ATN_Pilot said:
Eh, when I flew standups, I wanted every extra second I could get. Didn't care how much extra fuel I burned. The company knew it was rampant with the standup crews, and they didn't care. It was just assumed that we were flying right up to the clacker on every single leg.
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It's more of a mental thing, not grounded in any form of reality. On a 6 hour leg? Sure, picking it up from .75 to .85 is probably going to make a difference. On a 90 minute flight (or, out here on a 19 minute flight with only 5 minutes above 10,000) the difference between 290 and 330 is pretty negligible.
 
I wouldn't say negligible. Our average standup was about 90 minutes, and we could usually shave about 7 minutes off of that on average. That's sometimes the difference between the 7am van and the 7:10am van. That extra 10 minutes s important when you're flying standups.
 
PhilosopherPilot said:
We used to climb out in "climb 2" to save gas, but the company crunched the numbers and realized that the extra time at lower altitude was burning more gas than the fuel savings of being at a lower power setting. So now we go to "climb 1" as soon as we get cleaned up. It is a higher power setting, but we get to altitude quicker.

At any rate, it's what the company tells us to do, so we do it.
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Big derate climbs can also be bad for the engines. I know GE doesn't like us using CLB 2 anymore due to coking problems.
 
Derates actually increase fuel burn. The point isn't to save fuel, but to save on engine maintenance. We had power-by-hour with Rolls Royce, and they would drastically reduce their costs if you kept the engines in CLB1 for the first 9 minutes of the flight. When fuel prices spiked in '08, though, the fuel costs outweighed the savings from Rolls, so we switched to CLB power. Like I said, the accountants are watching it.
 
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