Blue-line Debate

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Tell ya the truth though, when I was working on my Private-multi, I had a Riddle-PRC instructor with 400-500 multi saying that I should reduce power to maintain blue-line at all times. I hope they're still not teaching that. /ubbthreads/images/graemlins/tongue.gif

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Nuts. Personally, if I could fly at Vne with an engine out in a Seminole, I certainly would. Because you can translate that speed into altitude if need be.

Maybe it's all of the Navy guys I'm flying with that talk about " potential/kinetic energy" as opposed to altitude and airspeed.
 
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The NTSB investigator will say "Well, he did an off-airport landing and ended up a fatality, but he held blue line +/- 1 knot! Woo!"

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Hey, don't get me wrong. If I start descending, then I'm firewalling baby! If it's between potentially losing an engine due to overexertion or a for sure landing where I don't want to, I'll take the potential engine loss. I'm just saying that my instructor (all three of 'em) are trying to beat the "take care of the good engine" thing into my head. Granted I can climb in the Seneca on one engine at around 110-115 mph, which is an okay bit ABOVE blue line. Nice thing about not training in a Duchess-ole in FL. Now, who knows what I'll get in the multi-roulette that's going on now....
 
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Maybe it's all of the Navy guys I'm flying with that talk about " potential/kinetic energy" as opposed to altitude and airspeed.

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Energy Management
 
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Two issues here
1. With an engine malfunction you don't have time to troubleshoot ( unless you are at cruise ), Do the Procedure at least up to Feathering. You need the Performance NOW not after trouble shooting. You don't need to find the airspeed that will give you the best climb rate ... the manufacturer has already done that ... blue line baby. Now once you move into larger twins there won't be a blue line on the Airspeed inicator, you will define Vyse on your pre flight performance card.
2. A ridiculous statement ... what instructor would rather fly into terrain ...? I say you are more apt to get into trouble NOT flying Vyse, if a few knots work better today then a few more work better tommorrow ... until you roll it in uncontrolled.


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1. You are correct, but the original question did not specify when the engine failure occurred. A general answer to a general question.
2. I realize that no instructor, no matter how retarded, would rather fly into terrain. But, I have met too many instructors who read 'the book' and then blindly teach what ever it is they read, without giving the subject any critical thought. An inexperienced CFI with a little bit of knowledge and an arrogant attitute does not do their students any favors.
3. In the Seminoles that Riddle uses, Vyse is 88 and Vxse is 82. Vmc is 56 and is a stalled condition. If you are at altitude and fly less than Vyse you can often hold an altitude well over 1000 feet higher than what the performance charts in the books show. If you can do this without slowing below 82, you are still well above stall and not in any danger of making a smoking hole in the ground. I realize that there are other twins out there that do not have the benign handling characteristics of the Seminole, if you fly one of these just use some common sense. If I can slow down just a few knots below Blue Line and increase my climb rate I am going to do so, assuming I need the performance. Blue Line, like the Red Vmc Line is only true for one set of conditions. It does not vary as much as Vmc, but you will not necessarily get best performance just by holding the published airspeed.
 
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Recently I've had run-ins with several Riddle instructors on the topic of blue-line during engine-out flight. Their contention is that no matter the performance, you should always fly at blue-line when an engine is inoperative. Fair enough. However, my contention is that if you can gain performance by flying a few knots below blue-line, you should do it.

I'm interested in hearing some thoughts from other multi pilots about how engine-out ops should be conducted. Keep 'er at blue-line, or experiment a bit?

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I hear this a lot, but keep it at blue line. While Vyse does change with weight, Piper does not provide a chart to compute actual Vyse. However, teaching CFIs here in Vegas we do a lot of drag demos, and we've determined blue line is actually the best speed to minimize altitude loss. I believe the high density altitude here may play a part, but it certainly amplifies any results. Remember the graph of curves for induced and parasite drag? Blue line (Vyse) is at the bottom of these curves, where parasitic and induced drag are minimized. Watching the VSI, pitch up and fly a few kts below Vyse and you will get a climb for a few seconds, but as the induced drag builds you will lose the climb and may even descend depending on density altitude. This is part of the drag demo that every MEI must learn, and exactly what I see every morning. While I don't agree with the Riddle mentality at all, I do teach students to maintain blueline.
 
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Tell ya the truth though, when I was working on my Private-multi, I had a Riddle-PRC instructor with 400-500 multi saying that I should reduce power to maintain blue-line at all times. I hope they're still not teaching that. /ubbthreads/images/graemlins/tongue.gif

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That's just nuts. If you are maintaining blueline and have power to spare, go full power and climb!
 
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I hear this a lot, but keep it at blue line. While Vyse does change with weight, Piper does not provide a chart to compute actual Vyse. However, teaching CFIs here in Vegas we do a lot of drag demos, and we've determined blue line is actually the best speed to minimize altitude loss. I believe the high density altitude here may play a part, but it certainly amplifies any results. Remember the graph of curves for induced and parasite drag? Blue line (Vyse) is at the bottom of these curves, where parasitic and induced drag are minimized. Watching the VSI, pitch up and fly a few kts below Vyse and you will get a climb for a few seconds, but as the induced drag builds you will lose the climb and may even descend depending on density altitude. This is part of the drag demo that every MEI must learn, and exactly what I see every morning. While I don't agree with the Riddle mentality at all, I do teach students to maintain blueline.

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Blue-line on the airspeed indicator only applies to sea-level, standard day, and MGTOW. I'm not denying the fact that blue-line works for you in Vegas, but down here flying 80-85 KIAS will literally improve your performance by 100-200fpm on most days. I proved this the other day by stablizing at 80 knots for roughly 1 minute. We went from a 300fpm climb to a 500fpm climb.

I personally think it's important to emphasize the fact that while blue-line is an important number to initially pitch for when you're cramming and cleaning, you can often find better performance at other airspeeds depending on conditions.
 
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I hear this a lot, but keep it at blue line. While Vyse does change with weight, Piper does not provide a chart to compute actual Vyse. However, teaching CFIs here in Vegas we do a lot of drag demos, and we've determined blue line is actually the best speed to minimize altitude loss. I believe the high density altitude here may play a part, but it certainly amplifies any results. Remember the graph of curves for induced and parasite drag? Blue line (Vyse) is at the bottom of these curves, where parasitic and induced drag are minimized. Watching the VSI, pitch up and fly a few kts below Vyse and you will get a climb for a few seconds, but as the induced drag builds you will lose the climb and may even descend depending on density altitude. This is part of the drag demo that every MEI must learn, and exactly what I see every morning. While I don't agree with the Riddle mentality at all, I do teach students to maintain blueline.

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I'm with the blue line crowd, I was taught that Vyse is at the area on the drag chart called L/D max. L/D max is the speed where the combination of induced & parasitic drag is lowest. This speed is where the wing is most efficent so the remaining engine has the least amount of drag to overcome (this also best glide). Since this is based on the wing shape it dosen't change (unless you add flaps for some crazy reason).

Now Vmc deffinatly changes and is useually less than the red line on the airspeed indicatior. The way I remeber it is based on your worst case secnerio. You've just taken off from a sea level airport when you lose the critical engine at max grosse with an aft CG and after you've done your engine faiure check list.

However airspeed indicators are sometimes wrong, and "if it's stupid and it works, it ain't stupid"! If you find a configuration that results in a better climb, then use it. /ubbthreads/images/graemlins/smile.gif
 
Blue line is, as has been stated, Vyse at max weight, SL,
ISA. Nothing more. Large aircraft do not publish it at all
as the weight range is so large you'd be losing way too much performance. For light aircraft, the couple of knots is less significant and the idea is to not have people trying to slow down to some unknown number in order to try to net more performance --- although some light aircraft manufacturers do publish a Vyse chart for different weights.
 
V2 to V2+20 is all we're concerned with in large jets.

Ha! here I say "large jets" when I fly a 'light twin'... Sorry Seagull! I'll go back to my quiet corner...
 
I teach my multi guys that upon engine failure first thing is "mixture prop throttle". I guess i have the same line of thinking as Doug. I'll determine that i have excess power first, then throttle back, then waste my energy and then find out i'm starting down. You're not really saving the engine anyway, it takes 20 seconds to slow down and if i had powered back and realized i'm slowing down to 88 that power is going right back in to stop the altitude loss.
 
what configuration is blueline published for?

ISA, SL, max weight. what about cowl flaps?

How do you figure out how many kts below blueline to fly for best performance assuming you're at something lighter than max gross? Can you use
[sq rt(current weight / max gross) x published blueline]


I know it's an old topic but from what I can tell there are two camps, one saying 'blueline' the other saying 'slower' but by some arbitrary 'few knots'. If slower is better but too slow is very bad then just how slow can we go?

I personally am of the blueline mentality because it's a nice line drawn on the dial and is 'easier' and safer - especially if the alternative is to fly an arbitrary speed below blueline and 'experiment with it' after an engine failure.
 
2 points to add/repeat:

1) Blueline is not a fixed number on the airspeed indicator.

2) If you are in an engine failure situation where altitude is critical, such as after takeoff, and you blindly pitch for 88 KIAS all the way into the trees, you didn't complete your mission.
 
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2) If you are in an engine failure situation where altitude is critical, such as after takeoff, and you blindly pitch for 88 KIAS all the way into the trees, you didn't complete your mission.

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So how much slower do I fly???
 
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So how much slower do I fly???

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The answer I'll give is probably what you weren't looking for. Whatever the situation dictates.
 
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The answer I'll give is probably what you weren't looking for. Whatever the situation dictates.

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So if blueline isn't happening, just pitch up until I start climbing right?
 
And what if you all lose your Airspeed indication?

Too many people it seem, rely on looking at the airspeed indicator. A natural feel of
the aircraft should have been established to allow the recognition of a Vmc event, and
thus an idea of controlability / area of operative control while in flight.

Going by the numbers is great for training (initially) to show a standardarized practice
of "expected performance", but I think too often people don't go full out, and push their
abilities or those of the aircraft, in order to be confident to simply fly the thing.

I think there may be a need for more intuitive flight training / physical / controlling by
the understood feel of the plane at times when, simply following a "procedure" may not
produce the best ( most effective ) result.

Everyone should be able to land, takeoff, and fly (manouvres) without the need to directly
use an ASI. If you can do this, it allows you to have your senses tuned to the actual
performance ability of your airplane at that moment in time.

I think a few will understand what i'm saying.

-Perpetual
 
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Too many people it seem, rely on looking at the airspeed indicator. A natural feel of
the aircraft should have been established to allow the recognition of a Vmc event, and
thus an idea of controlability / area of operative control while in flight.

I think a few will understand what i'm saying.

-Perpetual

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There should be a definate feel for when you're really beginning to run out of rudder.......
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But I see what you're saying, and agree with the concept of understanding the aircraft and what it's trying to tell you.

There have been many accidents where one of the causal factors, and critical links in the accident chain, was the aircraft trying to talk to the aircrew, but they either didn't recognize it, or ignored it. The recent Pinnacle CRJ accident comes to mind in this vein.
 
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