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Humpty Bump Part I

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The Humpty Bump is one of the most basic and versatile maneuvers in aerobatics. It consists of a combination of ascending and descending lines with half-arc or "loop" between both lines. In its simplest form, it is considered one of the basic aerobatic figures in which, for the first time, new pilots are forced to work with the aircraft at low speeds, with large gyroscopic forces produced by the propeller.


Despite this, it is a maneuver suitable for a sportsman-level pilot and within the performance capacity of basic aerobatic training planes like the CAP 10 and the Citabria.

In his book, "Better Aerobatics," Alan Cassidy, British Champion, aptly defines the Humpty Bump as: “ is the ideal platform for learning more about ultra-low speed handling, balance and elevator management.”

Currently, this figure is regularly used in practically every level of aerobatic flight due to its high adaptability.  It is normal to find a Humpty within an aerobatic program like mid-box figure, as a turn-around end-box maneuver, or when combined with portions of rolls on the vertical lines, as a wind-correcting cross-box maneuver.

Depending on the category/level, it's normal to add rotations between its lines, such as a full-roll, half-roll, full snap, etc. These maneuvers increase the figure's level of difficulty considerably, and consequently, its total Ks, since the rotations have to always be completely centered in the middle of the lines. The length of the line before and after the rotation should be equal, requiring the pilot to know when and in what moment he should begin each part of the Humpty maneuver.

The Humpty forms part of the repertoire of "must know" figures for any aerobatic pilot, since no matter his discipline, they can appear in any aerobatic competition table.  In this article, we will try to decipher the characteristics of this figure for correct execution, and we will analyze the important aspects to take into consideration for the performance of this figure during any competition.


Types of Humpty Bumps

The types of Humpy Bumps described below differ according to what the pilot does in the three arc segments of the figure.  So, for example, we talk about "pull" as a positive G maneuver, and "push" as a negative G maneuver.

The pull-pull-pull Humpty begins in upright-flight, is followed by a vertical pull, then another pull to make an inside loop, and a vertical descending line followed by another pull to level off.

Some types of Humpty Bumps

The pull-push-pull Humpty is a vertical pull, then a push to make an outside loop, a downline, and then a pull to level off.

The Laydown Humpty is a Humpty with uplines and downlines on each side of the half-loop at 45º to the horizon.  

The push-push-push Humpty begins in upside-down flight, then a push for a vertical upline, a push for a half-loop, and another push for upside-down level flight.

Double Humpty Bump
Double Humpty Bump


A new recently-incorporated type of Humpty Bump is the Double Humpty Bump. This is the same as the normal Humpty Bump, except that in the bottom part, after making the vertical downline, you have to push or pull to make a half loop arc and make another upline, then push or pull to level with the horizon.

In the Aresti catalogue (where all the figures used in this sport can be found), the Humpty Bumps appear within the Family 8: "Combination of Lines, Angles, and Loops."


Flying the Maneuver

According to Section 6 of the FAI Sporting Code, "Regulations for the Conduct of International Aerobatic Events" in Part 1 (Powered Aircraft) and in Part 2 (Glider Aircraft), it is specified how the radii and lines of the Humpty Bumps should be during an international competition. 

When evaluating a Humpty Bump, whether at the vertical or at 45º, it will be evaluated with the same criteria used in the combination of lines and loops indicated by Section 6. This means that for all these figures, the radii of the first (a) and last partial loop (c) should be equal. However, the half-loop in the middle of the figure (b) can have a different radius. These half-loops should have a constant radius at the moment the line breaks, requiring the plane's angular speed to vary during the half-loop.

The lines in these figures (A and B) can have different lengths , and therefore, the entrance and exit heights can be different. You have to remember that any roll in these lines should be completely centered.

Radius of the Humpty Bump
Radius of a Pull-Pull-Pull Humpty Bump

The Double Humpty Bumps, which include three vertical lines and two 180º looping segments, none of the radii should be equal, but they should have a constant radius. It is not necessary that the lines have the same length between them.  Identical to the conventional Humpty Bump, the entrance and exit radii of the figure should be equal, and if a roll is added in any of the three lines, it should be completely centered.

In the next article, we will focus on the more technical aspects of the figure and dive into the important characteristics of the figure for competition flight.

Read 31474 times Last modified on Saturday, 08 February 2014 16:29
Alex Balcells

- Profesional pilot, aerobatic flight instructor and competitor. 

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