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PearlPilot 03-22-2010 08:40 PM

mushing on final
 
In "Stick and Rudder" Langewiesche asserts that if too high on final one should raise the nose instead of the instinctive lowering, so that the airplane would "mush" and lose altitude. I have tried both of these methods and have a couple of questions/concerns about mushing. I have "mushed" on final only when an instructor was on board and have always lowered the nose and added flaps (if not already done so) when flying solo. I feel like raising the nose on final creates a dangerous situation in which a decrease in airspeed, and AOA, are a perfect recipe for a stall. Mushing on final feels at least for me to be a maneuver that requires quite a bit of finesse and if not done properly could lead to an unwarranted situation.

Photon 03-22-2010 09:12 PM

I don't teach that at all...
Power for altitude, pitch for airspeed

inky13 03-22-2010 09:17 PM


Originally Posted by Photon (Post 782507)
I don't teach that at all...
Power for altitude, pitch for airspeed

x2

Looks like you have a good understanding of stall/spin awareness, PearlPilot.

Golden Bear 03-22-2010 09:22 PM

I remember reading that book when I was a CFI and thinking, "Wow, we've learned a lot about basic aerodynamics since this was written!"

Although a classic, using Stick and Rudder as a primary source is a bit like a med student reading a Biology text written in the 1940s. Look up something written more recently.

* This should not preclude one from spending many nights pouring over Aerodynamics for Naval Aviators (it doesn't get any better than that), but save that for your CFI.

USMCFLYR 03-22-2010 10:02 PM


Originally Posted by PearlPilot (Post 782497)
In "Stick and Rudder" Langewiesche asserts that if too high on final one should raise the nose instead of the instinctive lowering, so that the airplane would "mush" and lose altitude. I have tried both of these methods and have a couple of questions/concerns about mushing. I have "mushed" on final only when an instructor was on board and have always lowered the nose and added flaps (if not already done so) when flying solo. I feel like raising the nose on final creates a dangerous situation in which a decrease in airspeed, and AOA, are a perfect recipe for a stall. Mushing on final feels at least for me to be a maneuver that requires quite a bit of finesse and if not done properly could lead to an unwarranted situation.

You do mean a decrease in airspeed and an increase in AOA is a recipe for a stall - correct?

USMCFLYR

hemaybedid 03-22-2010 11:53 PM


Originally Posted by PearlPilot (Post 782497)
In "Stick and Rudder" Langewiesche asserts that if too high on final one should raise the nose instead of the instinctive lowering, so that the airplane would "mush" and lose altitude. I have tried both of these methods and have a couple of questions/concerns about mushing. I have "mushed" on final only when an instructor was on board and have always lowered the nose and added flaps (if not already done so) when flying solo. I feel like raising the nose on final creates a dangerous situation in which a decrease in airspeed, and AOA, are a perfect recipe for a stall. Mushing on final feels at least for me to be a maneuver that requires quite a bit of finesse and if not done properly could lead to an unwarranted situation.

Sounds to me like they are talking about performance landings and ground effect. Instead of diving for the spot if you're to high, the best thing to do is maintain or slightly increase your angle of attack which allows you to fly through ground effect with the least amount of float. In contrast if you're low and have obstruction clearance the best thing to do is pitch forward to carry speed into ground effect and maximize your float to your spot.

shdw 03-23-2010 01:40 AM


I remember reading that book when I was a CFI and thinking, "Wow, we've learned a lot about basic aerodynamics since this was written!"
I unfortunately disagree, his dynamics were pretty spot on. Mushing gives you the steepest feasible glide slope, thus the shortest landing distance.

Disclaimer: Mushing in at stall is for 0.00001 percent of pilots in very rare situations. Don't be a retard, this isn't a save a bad approach maneuver. You perform this only when you have absolutely no other option available.



Originally Posted by hemaybedid
In contrast if you're low and have obstruction clearance the best thing to do is pitch forward to carry speed into ground effect and maximize your float to your spot.

Only if you are below best glide speed. Despite what is said about diving for ground effect it doesn't help you increase your range. This is especially true in high wing trainers like the Cessna as they get far less benefit from ground effect than their low wing Piper counterparts.

The loss of performance by increasing speed above best glide counters the slight benefits of reduced drag in ground effect. The result? A useless maneuver that, if used in a real engine out scenario and misjudge, could do more harm than good.


To the OP: He is right about mushing being better than diving. There is a key to this though, the key is he is right when speaking in terms of maximum performance. You have to weigh your skills as a pilot versus the ability to utilize the aircrafts full performance capabilities.

I would recommend reading the book Emergency Maneuver Training by Rich Stowell. He does a nice job explaining the relationship of the power required curve to a glide.

NoyGonnaDoIt 03-23-2010 03:22 AM

The concept is still basically sound, although I wince at "mushing."

Basic short field over obstacle landings involve a slower airspeed and higher descent angle (behind the power curve) than a "normal" landing. That's produced pretty much as Langewiesche described.

Yep, when high on final, I definitely get (and teach) the airplane into a short field obstacle descent configuration to increase descent rate and angle while keeping airspeed from increasing too much.

It's fun to watch the alternative. Nose down to the spot, increasing airspeed even with power at idle, and an overshoot because the airplane has way to much energy when it gets to the runway.

Notice: not one word about whether pitch or power is for airspeed or descent rate.

woodfinx 03-23-2010 06:24 AM

On my CFI initial the inspector was, albeit, bothered that so many instructors teach pitch for airspeed, power for altitude when demonstrating landings.

He took the plane from me and said "Watch...pitch for the runway, power for speed. And this works in ALL airplanes."

Needless to say I now only mention the power curve when teaching slow flight.

UAL T38 Phlyer 03-23-2010 06:34 AM

Thrust to Weight Ratio
 
I've been taught both ways (civl and military). The primary difference was about thrust to weight.

Light aircraft are generally pretty low-powered. Often times, the only way to speed up is by lowering the nose.

High-performance jets (fighters) generally don't have that problem, although when maneuvering well beyond the stall, even burner won't accelerate in some circumstances. Civil jets can easily have the same problem. (Think heavy airliner, fully-flapped, slow on final...thrust isn't totally effective to speed up if on the back-side of the power curve.

In any airplane, the real answer is: it's both. It depends on how far on the back-side you are, and whether there is adequate thrust to speed up. I primarily use throttle for speed, pitch for vector control...unless I run out of throttle.


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