Judging an example sequence

To the right is the BAeA Club category power sequence Form-B, showing the sequence with the wind from the right.

Explanation of the Forms

Judging Forms A, B and C, or the alternative Left and Right (L & R)

If the A/B/C forms are used then Form-A alone is used for entering the judges' marks. Forms B and C are mirror-images of one another, the "B" Form having the wind from the right while the "C" Form has the sequence reversed with the wind from the left.

The Left and Right forms are a more recent format that puts the sequence diagram to the left of the marking boxes so both pages provide a complete solution - one for each official wind direction. When these forms are used it is very convenient to scribble the marks and comments on the diagram beside each figure as it is flown, subsequently transfering them neatly to the column of grades boxes. This is especially advantageous when the assistant is "calling" from the judging form, almost impossible when the Form-A is in use.

The Chief Judge will decide which style of forms is used at each event.

The Official Wind

In this sequence the aeroplane must start on the "A" axis directly into the official box wind. The wind direction is clearly shown on the form. Some sequences start on the "B" axis, in which case the actual direction taken is chosen by the pilot to suit the circumstances.

Wing rocks (see Wing Rocks)

The sequence should be preceded by the statutory set of three wing rocks.

Height minima

For Club pilots the minimum allowable altitude before 'low penalties' apply is 1,500ft although the pilot should keep well above this level to avoid potential questions arising in the judges' head. Disqualification would result at 1,300ft.

Recording 'Lows'

If you feel that the pilot has flown below 1,500ft at any point in the sequence (i.e. between the wing-rocks) note the point at which this occurs, and it will be discussed after the sequence is finished. Flying too low is taken very seriously in competition aerobatics, and a pilot will quickly be asked to stop and his Proficiency Card may be reviewed if this occurs.

The Positioning or Framing mark

For the Club class the K-factor for Positioning is 10k. At the end of the sequence put your mark in the Position box.

An explanation of the 5 figures

Fig 1 - An erect positive Loop (see Loops)
Look for:

• We want a level CGT start on axis, with no roll or yaw.
• Mark the entry point with your pencil.
• A clear start point, ie. a positive transition from straight to looping.
• Throughout the looping segment the wings must remain laterally level at all times, otherwise the CGT flight path will diverge to one side or the other and the figure will be crooked or slanted to one side.
• Again - watch and memorise the CGT in the first quarter, this is your reference.
• Loops must be wind-corrected, a non-circular shape should be downgraded.
• Compare the 2nd, 3rd and 4th quarters against the first for size, position of end point and radius.
• There should be no yaw or roll throughout.
• The end of the 4th quarter should be exactly below the top, at the start level.

Fig 2 - A Half Cuban Eight (see Loops and Eights)
The Half Cuban combines both looping and straight line sections. A 5/8ths loop is followed by a 45° down line with a centred half-roll.
Look for:

• After the wing-rocks we want to see a clear start point followed by a steady pitch-change up into the loop.
• Throughout the looping segment the wings must remain laterally level at all times, otherwise the CGT flight path will diverge to one side or the other and the figure will be crooked or slanted to one side.
• Watch and memorise the CGT in the first quarter - this is your reference.
• The pilot must relax the stick back-pressure as the top is reached to keep the radius constant - if this is not done the radius will get smaller and the loop will be 'peaked' like an egg. The radius throughout must match the first quarter.
• At 5/8 of the circle with the aeroplane at 45° nose-down inverted, the loop must stop at a clearly recognisable point so you can see the 'end' of the radius.
• A short straight inverted line follows with the ZLA (not CGT) at 45° to the horizontal.
• The half-roll should be brisk, the flight path judged in CGT on the 45° descending line, to finish erect with 45° ZLA again.
• A moderate degree of yaw or pitching during the roll can be disregarded (CGT rules), but 'barrelling' or sinking away from the 45° projected line must be penalised.
• The 45° line must be continued to exactly reproduce the pre-roll line in length and ZLA. Line length before and after rolls are easy to judge, and must be the same.
• The final 3/8 loop to horizontal CGT should match the loop in radius.
• The exit can be lower (or higher) than the entry, but must be in level CGT on the "A" axis. Judging for the next figure starts immediately level flight has been reached.

Fig 3 - A Stall Turn (see Stall Turns)
Look for:

• A clear start point followed by a steady pitch-change with constant radius up to the vertical.
• An accurately maintained vertical ZLA up-line with no rolling or pitch changes.
• At the top a crisp 180° yaw with no bridging, i.e. the rudder-driven turn pivots around the wing-tip, no wider.
• An accurate vertical ZLA down-line with no pitch-change until the quarter-loop back to level flight starts.
• A 90° change of pitch with constant radius from start to finish, the exit being in level CGT flight.

Fig 4 - A 180° Turn (see Turns)
Look for:

• A smooth roll to at least 60° while the CGT remains exactly along the main box axis.
• The aircraft must then immediately pull into the turn and smoothly change direction through 180° with a constant angle of roll.
• At the 180° point with the CGT the turn must stop exactly on the box secondary axis, then the aircraft can roll smoothly back to wings-level.
• Neither the start or the end rolls should have the roll and turning elements co-ordinated as though it is a balanced PPL turn.

Fig 5 - A Slow or Aileron Roll (see Rolls)

• We need to see level and accurate CGT flight throughout.
• A constant-rate 360° roll without any sink or 'barrelling' during the rotation, with the exit line on the same CGT axis.
• Crisp start and finish points to the roll, each time with the wings level.

The Positioning Mark (see Positioning or Framing)

In the "Pos" column you can see that the judge has put his impression of how well each figure was positioned in front of the panel so every part of it could be easily judged. In this case the right side of the Half-Cuban was somewhat too far to the right (R), the Stall Turn was much too far to the left (LL) and the 180° turn strayed back too far to the right again (R). Each letter represents a half-mark downgrade, the total here from the four letters providing an overall downgrade of 2.0 points. The judge is then entitled to go up or down a half-mark to reach the final Position mark, though in this case the conclusion is 8.0 instead of a perfect 10.0.

Overall

This sequence is about as simple as it gets in power aerobatics - even so you can see that the judging explanation covers all the faults seen when arriving at the final mark. The total figure K here is 55, whereas at power Unlimited the 'Free Known' sequence is 450K - a huge difference. However if you can reason your way through this sequence you are well on track to having the experience to start judging at a BAeA competition.