MERGED power curve / floats posts

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aeroncasuperchief
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Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by aeroncasuperchief » Sun Nov 18, 2018 11:25 am

Ok, try #2 no funny stuff this time, just a serious thoughtful discussion !
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ant_321
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Re: Float flying techniques for the seasoned bush pilot

Post by ant_321 » Sun Nov 18, 2018 11:37 am

Just pull the stick back to your chest and give ‘er shit. Works like a charm.
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ant_321
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by ant_321 » Sun Nov 18, 2018 11:38 am

Tell us your take. We’ll let you know if we think you’re full of shit or not.
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hotdog1
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Re: Float flying techniques for the seasoned bush pilot

Post by hotdog1 » Sun Nov 18, 2018 11:38 am

:prayer:
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Zaibatsu
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Re: Float flying techniques for the seasoned bush pilot

Post by Zaibatsu » Sun Nov 18, 2018 11:46 am

So... you reduce power to accelerate out of the back side of the power curve to Vy, right?
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by 7ECA » Sun Nov 18, 2018 12:06 pm

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youhavecontrol
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by youhavecontrol » Sun Nov 18, 2018 12:41 pm

I think it's best explained by using the airplane on a treadmill model.
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Sockpuppet
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Re: The backside of the power curve

Post by Sockpuppet » Sun Nov 18, 2018 12:45 pm

aeroncasuperchief wrote:
Sun Nov 18, 2018 10:23 am
Are you sure?
I would have thought it would reduce the airspeed, I'm not sure of the physics involved that would allow it to slow the ground speed, how does that work?

If there was 0 wind, then airspeed ( TAS) and groundspeed would be the same. I am talking about the ACTUAL speed you are flying in the air, not what is indicated on the ASI
If you are talking the ACTUAL speed you are flying in the air, then that is airspeed, and may or may not be what is indicated on the ASI, but to say you are flying precision approaches on the backside of the power curve using ground speed as an indicator, then I suggest you take some advanced training with a qualified instructor.
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Sockpuppet
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Re: The backside of the power curve

Post by Sockpuppet » Sun Nov 18, 2018 12:52 pm

aeroncasuperchief wrote:
Sun Nov 18, 2018 10:19 am
Perhaps one of the unintentional reasons for installing Alaska (biiiiiig) tires on a higher powered tail-dragger ( other than the obvious reason- to land on rough, unimproved strips etc) is so that you can both be on the backside for take-off and land 3 point while on the backside due to the tires giving you a high 3 pt attitude.
Seriously?
By definition it would be impossible to take off behind the power curve. If you can increase your speed with power then you are NOT behind the power curve!!
Take offs with the big tires are done by lifting the tail(preferably with brakes) and then rotating, using the instantaneous increase in AOA that the tires provide, and then lowering the nose to ensure that you AREN'T behind the power curve(which would make climbing impossible).
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Sockpuppet
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Re: The backside of the power curve

Post by Sockpuppet » Sun Nov 18, 2018 1:20 pm

aeroncasuperchief wrote:
Sun Nov 18, 2018 9:37 am
If one is landing on a short snow covered ( 2 inches or less) strip, it would be wise to touchdown at the lowest SAFE speed ( that would entail a backside approach in order to be stable) this same strip is lots long enough for a take-off but too short in these conditions for a normal approach speed and landing. The V-1 cut and stop distance is not available in these conditions WHY do it at all? Because you must land due to an emergency OR because you want to for shits and giggles or practice?
Holy crap man, did you even read the link you posted from all your hero pilots? They all point out that the one downside to a backside approach is that it is UNstable!!
Please, stop messing around before you hurt yourself. Airplanes are unforgiving, and I hate reading stall/spin accident reports.
Trying things for shits and giggles is a very quick way to wreck planes(equivalent to "hold my beer and watch this")
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Zaibatsu
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by Zaibatsu » Sun Nov 18, 2018 1:32 pm

Lift demons and thrust pixies.

http://messybeast.com/dragonqueen/liftdemon.htm

But in all seriousness, who cares? There few things more useless for a pilot to know.
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by '97 Tercel » Sun Nov 18, 2018 1:53 pm

Weird thread..
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Gannet167
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Re: The backside of the power curve

Post by Gannet167 » Sun Nov 18, 2018 3:38 pm

Image
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dialdriver
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by dialdriver » Sun Nov 18, 2018 4:01 pm

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aeroncasuperchief
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by aeroncasuperchief » Sun Nov 18, 2018 5:53 pm

Tell us your take. We’ll let you know if we think you’re full of shit or not.
BOTH !
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aeroncasuperchief
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by aeroncasuperchief » Sun Nov 18, 2018 6:03 pm

The link you provided 7eca is ironically ammunition to prove my take on the backside of the power scenario in another thread!

https://www.av8n.com/
Back Side of the Power Curve

Imagine you are on final approach. On long final you are maintaining a speed near VY (a normal approach speed in many aircraft), using 1700 RPM of engine power. Then, suddenly, the tower controller asks that you land and hold short of a crossing runway. You decide to convert the normal approach to a short-field approach. This requires slowing down from VY to a somewhat slower speed. The procedure is shown in figure 7.3.
You need to shed some kinetic energy, as shown by the shaded area in the figure. Since that always takes time, you should immediately retard the throttle. You are now getting rid of mechanical energy (via drag) faster than it is being replaced (via the engine). You want to pay for this energy deficit by cashing in airspeed, not altitude, so you must pull back on the yoke and then roll in some nose-up trim to get rid of the force on the yoke. When the airspeed reaches short-field approach speed, you re-open the throttle. Returning to 1700 RPM will not suffice; you will need more power to complete the approach at this low speed than it would have at the higher speed.

Figure 7.3: Slowing Down on the Back Side of the Power Curve
This is an interesting contrast with the previous situation (e.g. figure 7.2). The required power increases as the airspeed decreases. Therefore you do not even have the option of making the speed-change with only one power-change. It requires two (opposite and unequal) power changes.
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aeroncasuperchief
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by aeroncasuperchief » Sun Nov 18, 2018 6:06 pm

It could be Lift Demons Im just not soo sure anymore
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aeroncasuperchief
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Re: The backside of the power curve

Post by aeroncasuperchief » Sun Nov 18, 2018 6:16 pm

and then lowering the nose to ensure that you AREN'T behind the power curve
Exactly!

If you didn't lower the nose while in ground effect, your backside point would either move forward ( with excess power) or move backward ( if you kept the nose up and were at full power and your power was not sufficient ( excess power) to pull out of the backside position !

Remember in flight , while in the backside, pulling back and adding full power only gets you a lower speed and likely an irreversible condition !
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aeroncasuperchief
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Re: The backside of the power curve

Post by aeroncasuperchief » Sun Nov 18, 2018 6:21 pm

Holy crap man, did you even read the link you posted from all your hero pilots? They all point out that the one downside to a backside approach is that it is UNstable!!
Please, stop messing around before you hurt yourself. Airplanes are unforgiving, and I hate reading stall/spin accident reports.
Trying things for shits and giggles is a very quick way to wreck planes(equivalent to "hold my beer and watch this")
Some fighter jets are soo unstable, they need a computer between the pilot and controls to fly it !! Airlines and carrier landing jets employ the "unstable" backside approach quite successfully . I have been around 54 years without 1 ding BECAUSE I recognize the risks, operate within them and have a few chicken bones within my body. :wink:
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Re: The backside of the power curve

Post by PilotDAR » Sun Nov 18, 2018 6:41 pm

If you are talking the ACTUAL speed you are flying in the air, then that is airspeed, and may or may not be what is indicated on the ASI,
Yeah, truth in that! My mighty STOL (Horton) C 150, with a low speed ASI installed, indicates to me that I can sustain stable flight at 22 MPH IAS. 'Seems impressive, but not really. When I put a swiveling pitot boom, and a second ASI, I found that the difference between IAS and CAS in that way behind the power curve configuration was great (and the Cessna chart does not present speeds that slow). 22 MPH IAS was really 41 MPH CAS. And, if I get the plane near the ground in that attitude, the tail tiedown ring bangs the surface before the mainwheels do, so don't do that [again :oops: ].
without 1 ding BECAUSE I recognize the risks, operate within them
Good in theory, but I'm the poster child for it doesn't always work that way! There are risks there to grab you even when there seem to be no Swiss cheese holes lining up at all! I mitigated all the risks, chose ideal conditions, briefed a competent pilot, and an accident still happened.
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shimmydampner
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Re: Float flying techniques for the seasoned bush pilot

Post by shimmydampner » Sun Nov 18, 2018 7:54 pm

If you're already that close to lifting off, what's the point of this "technique"? Is it due to a unique characteristic of the particular aircraft?
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aeroncasuperchief
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Re: The backside of the power curve

Post by aeroncasuperchief » Sun Nov 18, 2018 7:54 pm

Good in theory, but I'm the poster child for it doesn't always work that way! There are risks there to grab you even when there seem to be no Swiss cheese holes lining up at all! I mitigated all the risks, chose ideal conditions, briefed a competent pilot, and an accident still happened.
Yes. that is a humbling statement for all of us to get behind !
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pelmet
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Re: The backside of the power curve

Post by pelmet » Sun Nov 18, 2018 7:59 pm

What kind of aircraft do you test fly?
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C.W.E.
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Re: Float flying techniques for the seasoned bush pilot

Post by C.W.E. » Sun Nov 18, 2018 8:22 pm

I would apply the single float lift off procedure ( not many pilots do it well, most do it for show, I suspect)
I use that procedure for glassy water take off's.

And that is not a seasoned pilot procedure, it is basic float plane flying.
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jakeandelwood
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Re: Seriously, Is it Bernouieillei or Newton or both Part Deux

Post by jakeandelwood » Sun Nov 18, 2018 8:30 pm

The Bernoulli principle (however it's spelt) has been around since sailboats started using fore and aft rigged sails to be able to sail upwind. It just took us a while longer to apply it to an aircraft.
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