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common errors     part of the aerobatic figure hammerhead
page created 30.06.2002 - 21:29, last modified 27.09.2002 - 12:15 by

common errors
if things go wrong
   common errors

Errors during the hammerhead are most likely to occur during the pivot, which is the most unfamiliar segment of the maneuver for the aerobatic student, but they might also be committed during other stages. Let's look at them in sequence.


   On the pull-up to vertical, a line shallower than vertical is established.  

You are not paying attention to the wing chord line's angle with the horizon, and are establishing straightline flight too early.


   The time to pivot isn't recognized in time.  

The slipstream's buffeting of the fuselage is subtle and gentle. Watch for it carefully.


   The pivot is put off so long that the aircraft starts to tailslide back down in the direction from where it came.  

If it starts to tailslide, it is too late to continue with the hammerhead because the reversed direction of the airflow over the airframe might cause the airplane to behave differently than required in the hammerhead. At this stage, the maneuver should be aborted. This is accomplished by pulling the stick full aft and firmly holding there. Alien as this might sound, it is the standard technique for performing a forward tailslide, which is the advanced aerobatic maneuver you are now inadvertently flying. All that will happen is that the aircraft will arch forward into a dive. When the nose points straight down, release back pressure and recover from the dive.

   Rudder, aileron, and forward stick are applied simultaneously at the top of the pivot.  

This error will cause the aircraft to go off proper alignement in the maneuver. If you have trouble with sequential control application, verbally call out each control in the proper order and apply each control as you say its name.


   The controls aren't properly neutralized at the 45° point prior to the vertical downline.  

This error will cause the aircraft to be misaligned and off heading on the pullout. In some aircraft, at this point of the maneuver, forward stick and some rudder in either direction can cause an inadvertent inverted flat spin. Take great care to neutralize the controls.


   The aircraft is pulled out of the hammerhead after the pivot without being first flown in straightline flight along the vertical downline.  

This usually happens because the pilot is concerned with building up too much speed and is rushing the maneuver. Bear in mind that when you start heading down you are at zero airspeed. You have a reasonable amount of time to establish a vertical downline before you pull out.


   Excessive speed builds up in the downline.  

Just as you should not pull out too soon, you also shouldn't let too much speed build up on the way down. Be ready to retard throttle, and be careful not to overstress the airplane on pull out.

last modified 27.09.2002 - 12:15 by ,
article created 30.06.2002 - 22:00

   if things go wrong

Generally, four scenarios might threaten the safety of the flight if not properly recognized and handled:


An inadvertent tailslide at the top of the hammerhead


An inadvertent inverted spin because of a failure to neutralize controls while transitioning to the vertical downline


Excessive speed buildup on the vertical downline


Pulling excessive Gs on recovery


As described among common errors above, the inadvertent tailslide might occur if the pilot fails to initiate the pivot in time at the top of the hammerhead. It might threaten safety if not properly handled because the reversed airflow over the fuselage could cause the aircraft to enter a maneuver unfamiliar to the pilot with basic aerobatic skills, cause disorientation, and make it difficult to recover.



As described in common errors, the cure for the tailslide, which is an advanced aerobatic maneuver, is to simply complete it according to standard procedure. Pull the stick full aft, keep the rudders neutral, and wait. The aircraft will go over on its back into a dive from which recovery is simple.



Completion of the inadvertent tailslide is really a benign maneuver and should be practiced while learning the hammerhead.



An inadvertent inverted flat spin situation can develop in certain aircraft, especially the Pitts, Eagla, and some other high-performance aircraft, if rudder and elevator are not properly neutralized during the transition to the vertical downline, or if excessive forward stick is applied during the pivot. The control input for the inverted spin is forward stick and rudder in the desired direction of rotation.


So, if you are pointing straight down and carry forward stick and right rudder because you neglected to neutralize them, you might find yourself in an inverted flat spin. It is not at all dangerous if you know how to recognize it and what to do. (For specific recovery techniques, see your flight manual.) Power off, rudder opposite to the direction of yaw, and neutral stick will put you back into a straightline dive.


If your aircraft is susceptible to inadvertent inverted spinning under the described conditions, include the appropriate recovery training in your hammerhead curriculum.



Excessive speed buildup on the downline should be a rare problem. You transition to the downline at practically zero airspeed; however, if speed does build excessively, retard the throttle immediately, and simultaneously start your pullout. Eye the G meter to stay within limits.



Excessive G buildup on pullout might be related to having built up excessive speed, or you might just be too enthusiastic about pulling out. There is really no cure, only prevention. Focus consciously on G load throughout the pullout and you will stay within limits. If you notice the problem too late, ease off the stick immediately.

last modified 27.09.2002 - 12:15 by ,
article created 30.06.2002 - 22:21

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