Conference vmszoo::rc

1566.0. "EUropean Chronicles #4 - In RCSD October issue" by COWBOY::DUFRESNE () Fri Oct 08 1993 14:31

    



    European Chronicles
     by
    Marc Dufresne				� Copyright 1993 
    Domaine de Belle Croix
    17, rue Albert Camus
    77330 OZOIR-La-Ferri�re, FRANCE

    Tel/FAX: +33 1.64.40.12.24

    TITLE: F3J - Thermal Soaring genus Britanicus!


    Finally! After four months of slogging, the PULSAR was at point
    where it could be considered flyable. To get there has been
    subtantially more involved than I had anticipated. First, the
    airframe shipment got delayed due to some family problems. And
    then, when time came to ship, the movers had underestimated the
    weight/volume and consequently had to use an airline other than
    the one it had originally planned. This airline was a so-called
    "second-tier" carrier. To make a long story short, the crate left
    the US, transiting via Asia, got pre-empted on the way by a
    shipment of exotic animals, finally making it to Paris a week later.

    And no, I'm not making this up. It is not clear to me whether the
    crate went West all the way around the globe or first far to the
    East then West again. But from the looks of the crate on arrival,
    it was obvious that it had traveled far and wide. Luckily, its
    contents were not damaged. Wonders will never cease!

    Then, there was the business of getting the workshop operational.
    The previous one took me ten years to get to the point where I
    didn't have to worry about missing something. Here, I started from
    ground zero. Capital costs aside, the biggest issue is  finding the
    european equivalent of a favourite tool. And then realizing that I
    needed the american version all along 'cause the models at hand...
    I spent a princely sum in a local hardware store, on my last trip
    to the US fixing THAT problem. 

    Or to discover that the europeans do things differently. Not
    necessarily better nor worse. Just different. Like when I showed
    them the PULSAR fuselage covered with MONOKOTE. Or to show them
    that the dihedral is built in the wing and use a straight wing rod
    - they do the opposite. Or to notice that the stabilator pivot
    point on a european glider is always in the front, no further than
    25% of root. Any other configuration and the next time you try
    that banked turn on your big 3M ship at high speed has you going
    straight cause your servo can't take the aerodynamic pressure or
    into the ground because your servo blew a gear. 

    And I was also working to a deadline: France's first International
    F3J contest, held at Gisy-les-Nobles, June 20-21st. Gisy is
    located some 100Km south of Paris, an hour's drive from where I
    live. The venue was the local aeroclub's field: A wide open area,
    surrounded by farmland. The contest used the the club's old runway,
    which was condemned when some poor soul, some time back, overshot
    it and landed too close to the TGV train line which runs about one
    Km away. I mentioned earlier that my club had a bar. Well, these
    guys have a restaurant! With excellent food to boot. The club's
    set-up with hangars for power, gliders & helicopters, is pretty
    typical of any european aeroclub. 

    For me, this contest was also an ideal way to get back in the air.
    Except for the hand towing and group rotation, the format was
    similar to the open class thermal soaring contest in the US. There
    are some differences.

    F3J? The format comes from the British Open Class Thermal Soaring
    contest. There must be at least five rounds per contest. If more
    than five rounds are flown, then the final standings are based on
    your five best rounds. A two round fly-off with the best nine
    pilots determines the winner.

    In each round, pilots fly in groups of at least six, preferably
    eight to ten. Pilots are moved from group to group after each
    round, so that they get to fly with someone different. Each pilot
    is allowed two planes for the contest. And you must have two
    frequencies to fly on. This latter requirement is to deal with 
    posible conflicts as you move from group to group. 

    Each group is given ten minutes for working time to complete its
    flights during the regular round and 15 minutes for the
    fly-off. Each pilot is allowed two flights during working time.
    The last flight you make is the one that counts. You get points
    for flight time and precision landing. You loose points for flying
    over the working time. Overfly the working time by one minute and
    you get a zero. Land beyond 75m of your target and you also get a
    zero.  Scores are normalized for each group.

    Simple. No fuss. No muss. Its meant to be fun. The format is
    designed to allow various level of pilot competence and very
    different gliders to be competitive. Typical British fair play!
    Also, no high tech launching schemes. All you need is a 150m of
    monofilamant line with a max pull test of 2kg and a towman. A
    handreel is handy to wind up the line after launch. Pulleys are
    permitted for additional purchase. Patrick Tax, of the Dutch team
    showed up with a simple 2-channel polyhedral and the basic hand
    tow reel. His buddies, Martin Looman and Carl Van Vloten, brought
    the heavy artillery: a 3.5m ship and a two man tow system (see
    photog). One of the french teams got the prize for the ultimate
    system, with a two man, dual pully set-up. 

    Hand towing! Vision of the 100m dash... exhaustion... heart
    attacks... And a glider that barely makes it up to altitude...
    WRONG! The towman will be lucky to run more than 30-40m. With a
    pulley, about 20m. There is enough power in the run to rip wings
    off (That French team did just that) and also to get a good zoom.
    Speaking of which, I had a guy in the French team tell that F3B
    rules allow for tow launching but that towline is limited to 175m,
    to even things out with the 200m winch line. "If we could hand tow
    with a 200m line, we would not bother with the winch", he said.
    "The tow is much more powerfull."

    OK. So how does it work? When your group is called, you have five
    minutes to set up, ie, your tow man or team takes a walk unwinding
    the lines. Everyone would set up two lines, either as a spare in
    case of breakage or fast re-launch in case of bad flights. When
    working time begins, everybody launches as fast as possible. Since
    there is no max time, one aims to make most use of the working
    time. So it's a quick launch and then you fly as long as possible
    and land as close to the end of the working time AND as close to
    the pin as as possible. Things get real interesting at the end of
    working time with everyone getting into a landing pattern just
    about at the same time. 

    Bad air? Pop-off? Tough. One retry. Only exception: if a problem
    occurs that is beyond your control (collision, tangled tow lines),
    then the whole group gets to refly. When this occurs, the best
    flight time/landing from either the regular flight or the refly is
    kept. This means a refly can only improve you points.

    When the flying is done, you pick up your equipment and let the the
    next group do its thing.

    All right, back to the contest. 50 people showed up. 2 teams from
    Czech Republic, Italy and UK. 3 from France. 1 from Holland. The
    belgian were there with 4 tems.Most of the gliders were in the
    3.5m range such as the one shown here by Jack Sile. Also popular
    is the czech PROWLER with a similar construction of a fiberglass
    fuselage, foam sheeted wing center panel and built-up wing tips.
    The French, being different, were there with F3B ships. Regular
    rounds were flown in groups of eight. The fly-off was a group of
    the 12 best scores. EOLE, the French glider special interest group
    organized and ran the contest. As usual with Mr Maisse, everything
    went off like clockwork. The weather was ideal with light winds,
    warm sun of course, lots of thermals. 

    The PULSAR was full of technical problems. I used cables to
    control ailerons and flaps and it turned to be impossible get
    reliable control, much less to trim it. And I'll pass on the
    binding. So it's out with the cables and in with micro servos in
    the wing. I also discovered that the fuselage is not up to par for
    the kind of wear and tear found in this type of competition. I
    cartwheeled on landing and broke the nose off in the process. CA
    glue and aluminium tape quicky remedied that problem but as I
    compared with other gliders, it was obvious I needed something
    much more sturdier. After this, the ANTHEM fuselage doe not look
    overbuilt. These big ships, with their mass and moments, develop a
    tremendous amount of energy. Do something wrong and the results
    are not pretty. So I forsaked the flying and went to to help with
    launching and timing instead.
     
    I got a real kick at seing a group of eight pilots, about 4-5m
    apart get ready to launch all at once. I was used to contests in
    New England with 3-4 winches so I expected quite a few collisions
    but things went very smoothly on the whole. There where only two
    re-flys in the regular round. Over the course of the two days,
    seven regular rounds were flown with Riccardo Biffis, of Italy,
    finishing first overall, winning 6 out 7 rounds.

    The fly-off was done in perfect wheather. Just before launch, a
    pack of crows come through, riding a thermal. There must have been
    about a 100 of them. It was the first time I'd ever seen crows
    soar, much less as a pack. The first round was a real cliff
    hanger: everyone got off to a very good start and with thermal all
    over the place, everyone stayed up pretty well til the end of the 
    15 minute working time period. I was lucky to be the timer for
    Jaroslav Imiolek of the Czech Republic and also next to Tom
    Mertens from Belgium. I got a lesson in Thermal Soaring, just
    watching these two. And precision landing! These guys came in,
    side by side for landing with less than ten seconds working left
    and placed their gliders right on the pin. The final standings
    were decided on landing. I found having ten planes come in for
    landing all within 30 seconds of each other, on pins about 5m
    apart, to be a somewhat nerve wracking. I kept worrying about
    possible collisions. And was was just the timer.

    So it ended with Tom Mertens (Belgium), Jaroslav Imiolek (Czech
    Republic) and Francois Henninot (France) getting top individual
    honours. Francois, by the way, is the 1993 F3B French Champion.
    The top junior was Steeve Hansoulle, also from Belgium. He finished
    18th overall, an excellent performance, and in so doing, won a one
    year subscription to RCSD. In team competition, it was Italy,
    Czcech Republic and Holland. All in all, an excellent contest and
    weekend. A great time was had by all. 

    Cultural notes: At the awards ceremony, EVERYONE, from the lowest
    of card runner to the top flyer, got a prize in appreciation for
    his efforts. And after the awards ceremony, we are all treated to 
    a send-off "apperitif", courtesy of the organising committee: a
    wonderfull opportunity to relax and chat with fellow contestant,
    make plans for the contests (Belgium in August, Czech Republic in
    September). I've now added camping equipment to my equipment list.
    The field was turned into an instant village with its attendant 
    camaraderie, meeeting of old and new friends, swap meet and what
    not. 


     Continued next month.

       -END of text-
 

    This hand towing stuff sounds really interesting. We've discussed it
    before in this file, but I've never tried it. Marc, did you actually
    do any towing? If so, how do you know how hard to pull on the line? 
    Pull hard enough to snap the wings, then back off a tad?
    
    Dave
     

yup - did some towing. 

A straight tow (with no pulley) will not break wings and properly built F3J
and certainly not on an F#B. The wings that poped were done with systems
that had one pulley and two towers.

otherwise, The tower stalls (can't run) in the peak portion of the launch. 
The trick actually is to anticipate the zoom part and be ready to run like hell
to give the glider an good last burst.

md

    I managed to straighten out a heavy duty snap/swivel while handtowing
    a 100" Southwind using a single pulley.
    
    I do not recommend handtowing without a pulley unless you have a strong
    heart, the wind is blowing hard, and you have a light ship.
    
    Hand towing with a pulley is easy unless it is absolutely dead
    calm.
    
    
                                                           Regards,
    
                                                           Jim