TARMAC



The Official News Letter

Of The






June 2001



Your Executive Officers
El Presidente Andrew Parr
Vice El Presidente Chris Todd
Secretary Martin Seay
Treasurer Peter Cole
Committee Anton Lawrence
Committee Willie Morton
Chief Flying Officer Willie Morton
Safety Officer Niol Lockington
PPAB Peter Nicholson
PPAB Gordon Swan
PPAB Vern Booth
Editor Anton Lawrence


ARMAC Web site

Web copy of TARMAC
http://kirstant.orcon.net.nz/Armac/Tarmacs.html


Next Club Meeting, 3rd Tuesday of the month.
June 19th
At the Pikes Point Airpark Clubrooms 19:00

Committee Meeting at 18:30 Sharp.



Editorial
Another month goes by and still I've not been out for a fly. Done lots of work on the house and fixed the wife's car so it's not all bad. I believe there have been a few hardy souls still getting out so there must be more tales to be told.

Jon Farmer continues to be a regular contributor and has another project worth considering which he has written about.

Chris Todd will have another video for us to view at the next meeting. This will be on survival first aid. This should not be missed, as it is very relevant.

A useful site for Rotax owners. http://www.rotax-owner.com/index.htm

I found this on the NZ Microlights home page. http://nzul.listbot.com


The Great Ruapehu Mid-winter Fly-in
Ruapehu Gliding Club strip Raetihi
Friday 22 June- Sunday 24 June
Contacts
  • ·Organised by the Waikato Microlight Club
  • ·It would be helpful if you could indicate your interest in attending, but turn up anyway!
  • ·Stuart Parker         07 825 2800 or 025 223 6230
  • ·Peter Karl              07 823 6570 or 025 608 6692

    Anton Lawrence


    Anyone interested in some GA flights contact Ross Glover 576 6884




    Prez Sez
    Prez Sez, Well once again we had a quiet month, but the good news is that the club/syndicate bantam is now back in the air sporting a new set of wing covers (note the colour difference). While the covers were off some repair and maintenance has been carried out on the wings. Thanks go to Max Clear for technical advice, Barsal for the covers and to Willie Morton, Peter Cole for their time in doing the work.
    On behalf of the club I would like to welcome a new member, Matt Luethi into our ranks. Matt has come through our training scheme and is now looking to purchase his own aircraft. I understand it might be a bantam.
    Club night for May was down on numbers but the video presentations were very well received, thanks to Chris Todd for his efforts.
    We are at present, planning a club BBQ in the very near future at David Rees place. I would like to think that it will have a good turn out.
    It has also been requested to our PPAB reps that decisions made by PPAB which are relevant to all of us, are gazetted through both SAA and ARMAC newsletters

    Blue Skies

    El Prez

    Of Gyroscopes and Penguins.
    By Jon Farmer.


    During the `First War to end all wars' the fighter aircraft was evolving from the microlight type aircraft that were being used for artillery spotting. Engines were becoming more powerful and low hour pilots were having a lot of trouble with the first phase of flight - taking off. Their problem stemmed from the need to have a large diameter propeller to absorb the power of a slow revving engine and the long undercarriage required to give propeller clearance. In tail dragger configuration this meant that the aircraft had a very nose high attitude on the ground and the pilot had no forward visibility. During the takeoff run the inexperienced pilot had a very strong desire to see where he was going and tended to lift the tail as quickly as possible. This often resulted in a sudden and vicious swing in the opposite direction to the propeller rotation. That is, if the pilot saw the propeller turning clockwise or right handed then his aircraft would swing to the left. This effect is only experienced by tractor engine aircraft.
    The reason for this behaviour is twofold, in the first place engine torque is trying to revolve the whole aircraft in the opposite direction to propeller rotation and the aeroplane thinks it is meant to alter course in that direction. The second reason is due to the gyroscopic effect of the large and generally heavy mahogany propeller, even more pronounced with rotary engines. It is a strange property of spinning wheels that they resist any force you apply to them but move in the direction of your force at a point ninety degrees, in the direction of rotation, away. Take the front wheel of a bicycle when you are riding `no hands', lean to the left and the wheel steers to the left. Now lift the wheel off the ground and spin it then lean the bike left, which is the same as applying a sideways force to the topside of the wheel, and confirm that the wheel turns left just as though you had applied the force to the front of it. See diagram 1. Now spin the wheel backwards and lean the bike left. It will move as though you had applied that force ninety degrees away in the direction of rotation, that is at the back of the wheel, and it will steer to the right. This is a very useful piece of information to remember if you ever find yourself riding a bike `no hands' backwards.!!!
    Now, back to our novice pilot who has, shall we say, a right hand turning propeller. He lines up and gives her full throttle then pushes the stick forward to get the tail up. By this time the whirling prop has become a gyro wheel and lifting the tail is like pushing forward on the top of the disc. The gyro wheel reacts 90 degrees away in the direction of rotation which means the right hand side of the disc moves forward and slews the whole aircraft to the left which is the same direction that the torque is already turning the plane. The young pilot boots in full right rudder but it has no effect, the aircraft is in a left hand ground loop, the wingtip digs into the ground and the undercarriage collapses !!! If you don't believe this really happens then ask Sir Tim Wallis.
    The RFC (Royal Flying Corps) dealt with the problem in an innovative manner, assembling a number of wrecked aircraft so that they could be taxied but not going to the trouble of making them airworthy. The young pilots were let loose on these non-flying birds, which were nicknamed `PENGUINS', to practice their takeoff runs.
    For some while now I have been collecting the makings of a Penguin with a view to making it available at Pikes Point for training and perhaps to attract `Young Eagles' and others to join our club. So far I have the rear wheel off a motorcycle complete with suspension and brake donated by John Granger, a Lloyd engine with reduction donated by Alex McNab, a propeller which I had to buy, half a wing donated by Tony `Bicycle' Woodroofe and the makings of the other half of the wing and a pile of aluminium, controls etc from a crashed microlight. The one thing I don't seem to be able to find is the time to put all the bits together.
    My idea is to construct a penguin that balances on one wheel beneath its centre of gravity. See diagram 2. It will have ailerons, elevator and rudder and travel fast enough for these controls to be effective but not fast enough to become airborne. Dual tail wheels, at each end of the tail plane, will keep it upright when at rest. The wing halves will unplug for easy storage or transport to air shows etc. At the moment it owes me just under $300 and will probably be twice that by the time it is finished, so I will probably charge people to use it. Does anyone have any comments on this project?





    Leaning the bike to the left is like pushing on the top of the tyre. Movement of the spinning wheel is 90Deg in the direction of rotation.
    i.e. the front of the wheel goes left.


    The Penguin


    XFOIL
    By Anton Lawrence

    Over the years there have been a number of programs available to simulate the flow around an aerofoil. Most have been based on a code developed by Dr Epller. The code was reasonably sound.
    Another code which has been available only to those who had access to a unix machine was “XFOIL”.
    What the Epller based codes do is model what is known as the inviscid potential flow. Sounds technical but what it means is the flow is modelled as if there is no separation, that is the air flows nicely around the foil with no boundary layer affects taken into account. The boundary layer affects are then added as a separate component.
    XFOIL does this then works out the boundary layer characteristics, reshapes the foil to suit the boundary layer shape and then does the inviscid flow around the new shape as seen by the passing air. Laminar separation bubbles are also predicted. Like with most airfoil codes one can preset a vast range of variables not least Reynolds numbers and upper and lower surface trip locations.
    Once the airfoil coordinates are read into XFOIL the foil can be reshaped, smoothed and reanalysed making it easy to do iterative design. Foils can also be blended and the ratio of which foil has the greatest influence can also be adjusted.
    XFOIL can also do inverse design. This where the speed distribution, (Qspec to XFOIL), is specified and the resultant foil is produced.
    Full lift, drag and moment coefficient polars are produced, along with lift curve slope and natural trip locations.
    The most amazing thing is the program can be down loaded gratis from http://raphael.mit.edu/xfoil/
    There is a user group, which gets regular replies to sensible questions from the writers of the code.     http://groups.yahoo.com/group/xfoil
    It is a DOS based code and requires commands to be input through the keyboard, it does have a graphics output and modification of foil geometry or the Qspec can be done via the mouse. The code works fine on all windows machines.
    The program is not intuitive but is easy to learn, as there are a number of sample inputs one can use to get to grips with the way the code works. There is also a very good manual, which is down loadable, free of charge.
    If you are interested in airfoil design or analysis you can't be without this program, you could pay a lot of money for something not as good, I did!

    This is the basic list of XFOIL's various useful functions.
    1. Viscous (or inviscid) analysis of an existing airfoil, allowing
      1. Forced or free transition
      2. Transitional separation bubbles
      3. Limited trailing edge separation
      4. Lift and drag predictions just beyond CLmax
      5. Karman-Tsien compressibility correction
      6. Fixed or varying Reynolds and/or Mach numbers
    2. ·Airfoil design and redesign by interactive modification of surface speed distributions, in two methods:
      1. Full-Inverse method, based on a complex-mapping formulation
      2. Mixed-Inverse method, an extension of XFOIL's basic panel method
    3. ·Airfoil redesign by interactive modification of geometric parameters such as
      1. Max thickness and camber
      2. LE radius, TE thickness
      3. Camber line via geometry specification
      4. Camber line via loading change specification
      5. Flap deflection
      6. Explicit contour geometry (via screen cursor)
    4. ·Blending of airfoils
    5. ·Writing and reading of airfoil coordinates and polar save files
    6. ·Plotting of geometry, pressure distributions, and multiple polars

    A couple of screen shots from xfoil.

    Pressure profiles over top and bottom surfaces.



    Polar outputs



    Formation Flying Part II
    Taken from NZ Flight Safety June 1992



    Changing Formation
    All formation changes must he carried out as briefed. When changing, always maintain at least one wingspan or one aircraft length between aircraft, and always keep the aircraft ahead in sight.

    To move from echelon (port or starboard) to line astern, follow this sequence:

    1. ·Drop back one length clear of the leader's tail by reducing power slightly, and then re-apply power to maintain this position.

    1. ·Reduce height to clear the leaders slipstream.

    1. ·Move behind the leader. Using ailerons (anticipate levelling the wings to keep directly astern of the leader).

    1. ·Move into the correct line astern position.

    From line astern to echelon:

    ·        Move across.

    ·        Move up.

    1. · Move forward.

    The change from echelon one side to echelon the other is made via the line astern position and is a combination of the above two procedures.


    TAKEOFF

    Stream Takeoff
    The takeoff can be flown as a formation or in a stream. During the early stages of formation training, or in excessive crosswinds or on narrow runways, a stream takeoff may be necessary.

    After lining up (alternating left and right) indicate to the leader when you are ready. The leader will then give the running-up signal (or call) at which time everyone sets the prearranged rpm with the brakes on.

    The time interval between aircraft rolling is normally eight seconds; as soon as the preceding aircraft starts to move, count eight seconds and then commence your takeoff.

    The leader should climb straight ahead to at least 500 feet agl and then turn to allow the formation to join quickly. If the formation contains a number of aircraft the leader should extend the climb out before turning.

    Formation Takeoff
    Line up in formation and set rpm against brakes when indicated. The leader will then give the signal for the commencement of the takeoff, at which stage all aircraft should roll together. The leader does not use full power, so that the rest of the formation has some power available for corrections. During the takeoff roll, maintain the formation position and follow the leader's actions.


    JOINING UP
    Joining the formation (after a stream takeoff or after a break) must be done in a well-controlled manner and with extreme care.
    Never, never join a formation from above.

    Aim to position below and behind the leader at about two wingspans out (note, if the leader appears to be above the horizon, you are below the leader, and vice versa). As you pass this position you must have everything under control -remember inertia and closing speed. Then move up and, if necessary, forward to position on the same plane and on the extended echelon line. Then move slowly and diagonally, in and forward, to the correct position.
    A turning join allows aircraft to join the formation more quickly, as the leader does not continue to fly away from the joining aircraft. It does, however, require better judgement on the part of the joining pilot.


    Never, never join a
    Formation from above.

    Following aircraft should turn inside the preceding aircraft to intercept the formation as quickly as possible. This “cutting the corner” is equally applicable for sections in a large formation as for a single aircraft.

    It is important that the lead aircraft settles down to the agreed cruising speed as soon as possible. The following aircraft may then fly at the same airspeed, gaining position by use of a shorter radius turn. This way, leeway is rapidly made up without excessive changes in airspeed.

    To intercept in the shortest possible time, the joining pilot should maintain a rate of turn that keeps the lead aircraft stationary in the field of vision. If the lead aircraft appears to move forward the rate of turn should he increased - if it appears to move backwards the rate of turn must be decreased.

    During all join-ups it is imperative that, as the joining aircraft, you remain below and two spans out until you are stable. Then, and only then, move slowly into the correct formation position

    BREAKING AND
    REJOINING FORMATION

    If at any stage during formation flying you are unable to safely maintain Station - due to the sun's position, your disorientation, or when sight of the leader is lost - a positive break away must be made. The direction and manner of break will depend on your position in the formation and on the reason a break is necessary. You may need to use power to assist in clearing the formation.

    Having got safely clear of the formation, a normal join-up should then be carried out.

    If you misjudge a join-up always go under and behind the leader. The leader should maintain a steady flight path unless requested otherwise.


    LEADING A FORMATION
    Good formation flying depends on good leadership, and the leader can considerably ease the task of the formating pilots. The leader is responsible for the briefing before flight and, in the air, for the overall safety and airmanship of the formation.

    Manoeuvring and Handling
    The leader must always consider what effect any action might have on the formatting pilots. The main points to consider are.
    1. · All manoeuvres should be carried out smoothly and accurately, and they should be within the capabilities of all the formatting pilots.
    2. ·When manoeuvring (e.g., avoiding weather, positioning for circuit rejoin) make allowance for a much greater turning radius than for a single aircraft. Manoeuvre entries and recoveries should be made gently, with bank restricted to moderate angles.
    3. ·Some or all of the aircraft in the formation will at times be lower than the leader, and allowance must be made for safe terrain clearance for the whole formation.
    4. ·Maximum and minimum power settings must never be used by the leader, because formating pilots must be allowed a wider throttle range than the leader in order to maintain position.
    5. ·The leader must avoid slow speeds.

    Commands and Signals
    Control of the formation can usually be exercised through radio calls. Instructions are given twice followed by the word “go", at which time the action is commenced. For example, "echelon port, echelon port, go".

    Sometimes radio calls may not be possible or practical (e.g., on a busy frequency, or in the event of radio failure) and hand signals must be used.

    All radio calls and hand signals must be clear and unambiguous. When using hand signals, the leader must ensure that wing pilots are watching when the hand signal is given. The leader must be careful not to anticipate the action, such as rolling into a turn before the turn signal is complete.








    Hand Signals
    Action Hand Signal
    Ready for takeoff   Thumb up
    Running up (To predetermined rpm when cleared for takeoff) Hand raised, forefinger extended upwards and circling motion in horizontal plane
    Commence takeoff Chopping motion forward with edge of flat hand
    Change power Movement of fist forward/back (simulating throttle movement)
    Climbing Forefinger pointing upwards
    Descending Forefinger pointing downwards
    Levelling Sideways movement of flat hand, palm down, at face level
    Turning Forearm vertical, hand flat and parallel with line of flight, then moved right or left as necessary
    Straightening Chopping motion forward with edge of flat hand
    Selecting flap Hand flat with palm down, bend fingers down and up.










    Airmanship
    A good leader must display a high standard of airmanship; the leader is the eyes and ears of the formation. Points to bear in mind include the following:

    1. ·Lookout. In close formation, the attention, of formating pilots is concentrated on the leader, who must assume the responsibility of lookout for the whole formation. The leader must be aware of the greater airspace taken up by the formation, and its reduced manoeuvrability.

    1. ·Navigation. The leader is responsible for the navigation of the formation. Fuel states must be obt4ined periodically; the leader should appreciate that formating aircraft will have a higher fuel consumption than the lead aircraft.

    1. ·Position of the Sun. Whenever possible, the leader should avoid flying directly up-sun of any member of the formation.

    1. ·Manoeuvres. The leader must know the capabilities of all the pilots in the formation and handle the formation accordingly.

    REJOIN AND LANDING

    Rejoining the Circuit
    Rejoining the circuit should be well thought out and briefed. It is important that the leader plans ahead so as to reduce any tendency to rush the rejoin. The circuit can be joined via a buzz and break or via a formation landing.

    Break and Stream Landing
    The leader should approach on the heading of the runway in use, slightly off to the non-traffic side, with the formation in echelon starboard for a left-hand circuit (or vice versa).

    On crossing the upwind threshold the leader banks and pulls away sharply to the left, followed in order at briefed intervals by the rest of the formation. This turn can be either 90 degrees to crosswind then 90 degrees to downwind, or a smooth continuous turn of I8O degrees to the downwind position.

    After the aircraft ahead has broken away, look straight ahead and count the time interval (normally "break, break, go"). Ensure that you keep the leader on the horizon, and that you maintain your longitudinal spacing.

    (The military buzz and break procedure makes the approach below circuit height and climbs to circuit height after the break in order to lose airspeed.)

    The break must be made in a controlled and disciplined manner. It is not intended as an excuse for a cowboy act. Some years ago at an air show overseas,     one aircraft made a somewhat more spectacular break than the normal 180-degree turn. Instead, a 90-degree steep turn was followed by a flick and power-on spin to the right - which ended when the ground intervened.

    Only the leader makes the downwind and/or base radio call.

    Aircraft normally land alternately left and right on the runway. The speed over the threshold should be slightly higher than usual, and all aircraft must roll to the end of the runway before turning off.


    Formation Landing
    With the increasing numbers of tricycle gear aircraft, formation landings have become more common. A formation landing is not recommended with tail wheel aircraft. These aircraft are less forgiving if not landed with precisely the right attitude and speed, and maintaining directional control is more difficult than in a nose wheel aircraft.
    Formation landings are possible only on runways, which are wide enough to ensure adequate lateral separation between aircraft. As in flight, any overlap of wingtips is extremely dangerous - if the aircraft ahead suffers an engine failure a collision is inevitable.
    Formation landings should be attempted only by pilots who have attained a high standard of formation flying. Absolute confidence in the leader is essential.



    …the leader is the eyes and ears of the formation.


    It is vital that the leader flies a very accurate approach so as to allow the wing pilots some power margin. During the approach, the leader will lower up to three-quarters flap only, depending on prevailing conditions. If formating pilots do not lower flap promptly on each signal, they may overshoot the leader and be unable to regain formation. If you overshoot the leader at a low airspeed, regain formation by turning away from the formation and then back towards it again; do not throttle back and raise the nose of the aircraft to lose speed - this may lead to a stall.

    Turns should be gentle, and the leader should use as much power as possible so that the formation can keep station comfortably. On final, the leader should reduce power gradually until the required airspeed is attained, but not throttle back fully until on the ground or, with a small airfield, crossing the threshold.

    When the formation crosses the threshold the leader should land normally. Formating pilots should keep station on the leader and not attempt individual landings - in effect, the leader lands the complete formation.
    Once on the ground the leader should gradually close the throttle and slowly come to a stop.

    Debriefing
    A thorough debrief should be carried out. Review the whole flight, in particular any aspects that did not go as planned.


    SUMMARY
    Formation flying provides an opportunity to undertake a flying activity, which involves teamwork, with success depending on all members of the team. It requires a high level of skill, and confidence in the other members of the team is essential. The intense concentration required can be both physically and mentally tiring.

    Formation flying is a great challenge, it's fun, it can be very satisfying - but it can be dangerous and must not be under-taken lightly.

    References: RNZAF and RAF training Manuals,
    Manual of Flying and ground training
    Published by BLAC,
    The Flying Instructor's Patter manual by Peter Phillips and Robert Cole, and Flying in Formation by Frank W.Hampson.



    Trade And Exchange.
    Private owners only
    Contact the Editor to place an add
    813 6404hm 025 354 998wk
    kirstant@orcon.co.nz

    Trike, FXN, current air cert, plenty of instruments, long range tank, rainbow wing a pleasure to fly, low engine hours, $3,800.00 neg contact Alex; 09 5366815 h or 09 5342190 e-mail href="mailto:,atocollision@paridice.co.nz"atocollision@paridice.co.nz

    Koenig  "Pagojer" 18 Hp 3 Cyl radial engine, with prop, cage, and  harness for powered 'chute. In good condition, reconditioned a few hours ago. $2000. Further details from:  BRODIE ANDREWS, ph. 8175433"