Whip stall and vertical reverse?

Diana

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Diana
Ran across the phrase “whip stall” today and wonder how it is different from a regular stall.

Another totally unrelated question: the “vertical reverse” maneuver is on my placard in the Citabria, but I can’t find a good reference describing what that maneuver is. Anybody know?
 
Diana said:
Ran across the phrase “whip stall” today and wonder how it is different from a regular stall.
Diana, can you write down the sentence that this is in? I've never heard of it, either.
 
Toby said:
Diana, can you write down the sentence that this is in? I've never heard of it, either.
"The hammerhead stall is not a recommended maneuver, for if the rudder is applied too late, a whip stall will occur."
 
Diana said:
Ran across the phrase “whip stall” today and wonder how it is different from a regular stall.

Another totally unrelated question: the “vertical reverse” maneuver is on my placard in the Citabria, but I can’t find a good reference describing what that maneuver is. Anybody know?

A whip stall is generally considered a stall during a rapid pitch up. In such a case the angular momentum (in pitch) causes the airplane to go deeper into the stall than it otherwise would. Done with enough agressiveness and/or in a steep enough attitude and you will actually drop backwards before the nose falls at which point the nose will "whip" downward "with great enthusiasm".

"Vertical Reverse" sounds like an air combat maneuvers expression. Here's one description:

68. Vertical reverse.--a. General.--The verticalreverse is a training maneuver belonging to the spin or snap roll family and as such, during its performance, the movements of the airplane are rapid but controlled. The maneuver has the following useful training purposes:
(1) Requires good performance and understanding to steep turns.

(2) Accentuates errors resulting from either violent and poorly timed effort or overcautious effort.

(3) Demands perception as to gain or loss of speed and prompt physical responses.

(4) Requires trained responses rather than impulsive erratic reactions.

(5) Requires orientation during rapid movements of the airplane.

(6) Accentuates the value of timing efforts, especially that of relaxation, when at reduced flying speeds.

b. Execution..-The vertical reverse is a quick change from a right to a left steep turn or vice versa. From a turn with a bank in excess of 45° apply firm pressure on the rudder pedal in the direction opposite to turning, and as soon as the airplane starts to respond pull straight back on the stick. As the airplane responds to these controls, apply ailerons firmly in the direction of rudder use, still continuing the backward movement of the stick and firm pressure on the rudder pedal. The airplane will start up in a steep climb swinging in the direction that ailerons and rudder are being used. Before flying speed is materially reduced, start easing forward on the stick, still continuing efforts on ailerons and rudder. As the airplane approaches the desired angle of bank gradually relax efforts on all controls, timing this action so that it is completed when the airplane has assumed the desired attitude. Correct small errors in the new turn with light, well directed efforts.

c. Comments-(1) When properly performed it should be possible to resume flight without any break in the rhythm of turning or, in other words, the airplane should not suddenly stop and then resume turning as gross errors are corrected.

(2) The instructor should emphasize that smooth performance requires positive control movements and well timed, gradual relaxation of the controls.

(3) The initial steep turn should be well executed otherwise errors are carried into the maneuver and their cumulative effect is to destroy performance. The common tendency is to anticipate the reverse before the turn is well started. When this is done, such gross errors result that it is better to start the maneuver over again.

(4) Upon completion of the maneuver, speed is materially reduced. At this time violent pressure, if applied to the ailerons in order to reduce the angle of bank, or to the elevators to prevent the nose falling, will result in further diminishing the available speed and consequent loss of control. Under these conditions, if control abuse is carried to an extreme the airplane will either fall into a spin, or lose considerable altitude before recovery can be made. To stop the airplane in the desired attitude properly time relaxation of the controls. This last is the only positive and unfailing method to be used but because of its simplicity it is seldom done.

(5) After the peak of the maneuver has been reached, maintaining pressure back on the stick will result in the start of a spin and such rapid rotation and loss of control that all semblance of a vertical reverse will be lost. The student should be cautioned that when extremely rapid rotation takes place at this phase of the maneuver it is undoubtedly due to this cause, and he must completely relax on all controls and then, after the airplane has freed itself from control abuse, regain control.

(6) Due to the possibility of accidental spins, vertical reverses should be practiced by the student at an alitude well above 2,000 feet.

(7) The most common fault is the tendency to bring violent back pressure on the elevators after the sudden direction change resulting in a stall or spin. With practice the average student can make continuous reverses, changing direction 180the airplane will without excessive loss of altitude.
 
Diana said:
"The hammerhead stall is not a recommended maneuver, for if the rudder is applied too late, a whip stall will occur."

In this case the reference is to a very rapid change in pitch from straight nose up to straight nose down. It would probably feel like you were riding on the end of a whip that was "cracked". BTW this considered very abusive to the airplane, especially the tail structure and therefore isn't recommended for any airplane that isn't extremely strong. I'm sure a Citabria doesn't qualify and I doubt that a Decathalon does either.
 
lancefisher said:
you will actually drop backwards before the nose falls at which point the nose will "whip" downward "with great enthusiasm".

Oh, my. "Great enthusiasm". :eek: Have you done one of those?

lancefisher said:
"Vertical Reverse" sounds like an air combat maneuvers expression. Here's one description:
Whew. Wonder what that is doing on my placard. Don't think I'll be doing one.

Thanks for the input Lance. :)
 
Diana said:
Oh, my. "Great enthusiasm". :eek: Have you done one of those?

In the Starduster, but not the Porterfield. The rapid pitching wasn't all that voilent from the back seat, but the ride in the front might have been more abrupt. Even in the biplane we decided to avoid tailslides at all costs (which is probably why I never learned to do a hammerhead properly) because we didn't have the extra struts the designer recommended for the tail.
 
OK, is it just me? How many others had to fly Lance's description of verticalreverse with their hand to follow the steps described? :)
 
FYI-

A "Whip Stall" is entered from a "Tail Slide" in which the aircraft is not quite vertical, after slidding aft the weight of the engine causes the nose to pitch forward VERY, read EXTREMELY, rapidly. I've done them in a Stearman, I would not consider them in a lesser plane, it is an excellent way to clean all the accumulated debris from inside the fuselage...................quickly.

A "Vertical Reversement" is simply a top rudder stall from a tight turn, while doing a tight left turn add right rudder and accelerate the turn until it stalls, stop the resulting snap roll in the opposite turn and you've performed a "Vertical Reversement". It's really a half Snap Roll from steep bank to the opposing steep bank.

Tom-
 
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Re: Whip stall and vertical reverse?...........More

FYI-

The "Tactical Vertical Reverse" Ken linked to is much like a Hammerhead minus the stall and has no relationship to the common Barnstormer Aero Vertical Reverse.

In a Tail Slide it is absolutely imperative that the stick and rudders be held neutral to avoid serious damage to the structure. I've just recently seen a Citabria that exhibited signs of both ailerons hitting the stops in a tail slide, one aileron up, the other down. In addition to the airframes Negative G tolerance control surface strength, hinge strength, and tail feather bracing are of CRITICAL import.

Tom-
 
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