Judging an example sequence

To the right is the BAeA Club category 2017 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 1,000ft.

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 - 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 2 - A Stall Turn (see Stall Turns)
Look for:

  • A crisp 1/4 loop CGT pull to the vertical, with a smooth and constant radius.
  • Accuracy of the ZLA up-vertical line.
  • The turn-around without 'bridging', free of yaw and roll.
  • Accuracy of the ZLA down-vertical line.
  • A crisp 1/4 loop CGT constant radius pull back to horizontal. The entry and exit radii must be smooth. The entry point for the next figure starts immediately.

Fig 3 - 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 4 - A half-Loop and half-roll (see Loops and Eights)
Look for:

  • A clear start point followed by a steady pitch-change up into the loop.
  • A smooth and accurate half-loop with all the above looping criteria applied.
  • The half-loop is complete when the aircraft is directly above the start point.
  • At the end of the half-loop there should be an immediate roll either to the left or the right, the aircraft finishing in a horizontal flight path with the wings level and without any visible gain or loss of height.
  • If the roll starts before the 180° half-loop is complete or there is any perceptible line between the end of the half-loop and the roll then the usual downgrades apply.

Fig 5 - A 270° 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 270° with a constant angle of roll.
  • At the 270° point with the CGT on the box secondary axis the turn must stop and the aircraft smoothly roll back to wings level.
  • The second roll must also be accomplished in a straight line - 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 6 - A Slow or Aileron Roll (see Rolls)

  • Level and accurate CGT flight throughout.
  • An even-rate 360° roll without any sink or 'barrelling' during the rotation, onto the same CGT axis.
  • Crisp start and finish points to the roll, wings level.

Overall

This sequence is about as simple as it gets in power aerobatics - even so you can see that the judging explanation runs to quite a long page (with some of it on other pages too!). The total K here is 66, 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.