Conference vmszoo::rc

    Kay tried it last week when it turned out that his upstart didn't have
    the sustaned omph for my 2-meter brick. We used the highstart normally
    and then Kay grabbed it and pulled it some more when it started to sag.
    It worked better than without it but it wasn't purely a hand tow. Do you 
    use the reel/spool as a turn around so you're moving WITH the wind to tow?
    
    I hadn't read about it but Kay had and it was interesting on a day when
    we weren't getting much altitude and just horsing around. It did show
    promise and I'd be interested in reading more.

    Jim,
    I'd be interested in hearing more about your spool also. Do you
    reel the line in immediately after it releases from the plane?
    The pictures of the spool units that the British use in their
    F3J events appear to be a custom made unit with a regular handle,
    looks sort of like an elongated fishing rod and reel assembly. I've
    no clue as to where to get one. Do any British noters know anything
    about F3J events? I know the rules, somewhat, and would like to try an F3J
    event if I can drag some of the other club members kicking and
    screaming into the twentieth century,
    A recent issue of RCSD, Oct. or Nov., has a good article on F3J
    techniques.
    
    Terry
    

    re: -1
    
    I tried to draw(type) a picture of the setup but wasn't too successful.
    I will attempt to explain by using an example, assume the line you are
    using is 500 feet long.  Secure a stake in the ground approx. 490 ft.
    from where the glider will be launched.  Attach the line to the stake 
    and the tow ring to the glider's towhook.  The towman is standing at
    the stake 490 ft. away from the pilot who is holding the glider in the
    air ready to be launched.  The towman takes a spool(for my first
    experiment I simply used a plastic Craft-Air high start spool with all
    the line and rubber removed) and loops the line around the spool.  The
    towman then walks backwards the 10 ft. necessary to take the slack out 
    of the line.  He then yells to the pilot that he is ready and starts
    to walk away from the pilot while pulling the spool.  At this point the
    pilot throws the glider upward and the towman will immediately feel the
    force of the glider like flying a kite.  He then continues walking
    backward adjusting the velocity of his backward movement based on wind
    speed, weight of glider, and angle of climb.  Now believe it or not the
    force a 2-meter(Gnome) put on the spool was enough to make me stop dead
    in my tracks, in fact on windy days you will find yourself having to
    walk back toward the stake to prevent the wings from folding.  The
    force this 2-meter glider put on the spool caused the monofilament line
    to score the hard plastic of the high start reel.  I have  since
    fabricated a free turning spool made from a clothesline pulley, I am
    sure it will work much better.  A commercial hand tow winch is
    available from Graupner for $42.  It can be special ordered from Hobby
    Lobby.  I highly recommend you try this method, I think you will be
    very pleased with the results.
    
    Regards,
    
    Jim

    Very neat. One foot of pull translates to two feet at the glider end
    (one foot on each side of the spool) I'll have to try it with Kay
    sometime. If you made a handle for the spool that allowed it to turn (a
    "u" around the spool with an axle through the top that you held at the 
    bottom)

    
    
    Ah, I get the picture Jim. A very nice method that allows you to
    experiment with hand towing without getting new equipment, while
    at the same time closely duplicating the feel and efficiency of
    the F3J method, which simply grabbing the line and running a la
    kite flying doesn't do.
    One more question. If the Graupner hand winch has to be special
    ordered from H.L. , I assume it's not in their catalog. I have all
    the H.L. catalogs for the past 3 years and haven't seen it.
    
    Terry
    

    Another variant is to have the pilot and the helper hold pulleys, so
    the string is pulled at 3x the speed at which the pulleys are moved
    apart.
    
    I haven't done this, but an aeromodelling encyclopedia I have had some
    line drawings...
    
    ajai

    The Graupner hand towing winch has never been shown in any Hobby Lobby
    catalog, but I have the coffee table Graupner catalog(mostly in German)
    which came from Hobby Lobby($15.95) and they claim they can order
    anything from it if payed in advance.  I simply looked at the picture
    of the device, then adapted a clothesline pulley by building a wooden
    handle around it, total cost about $7.00.  If you build one make sure
    it will accommodate both your hands, because I am not kidding if you
    launch a 3-meter sailplane on a windy day a single hand is not going
    to be enough.  Any R/C magazine from England (RC MODEL WORLD) sells
    these devices via mail for 21.95lbs plus shipping.  This method of
    launching has been used sucessfully for a long time in England.  Higher
    launches may be achieved because you are not lifting the weight of a
    high start, plus very long line can be used.  Since there seems to be
    some interest in this, let me further detail my experience.  The very
    first time we (my father and I) tried to launch his 2-meter Gnome(32
    oz.) we used a small high start reel with light plywood side flanges,
    with a wooden dowel in the center.  Well since a high start reel is 
    several inches wide the line has a tendancy to move side to side which
    broke the light ply flange about half way up.  I simply stuck my arm 
    out alowwing the 80 lb. monofilament line to loop around my coat and
    continued the launch using my arm as the turnaround- the launch was
    spectacular.  This is when I knew this was going to work well.  We
    then unrolled the line and rubber from a plastic Craft Air high start
    reel to try some more launches.  Holding the reel by its dowel with
    one hand is almost impossible in a 10mph wind- you won't believe how
    hard a 2-meter glider can pull!  My last bit of advice is recognizing
    the difference in "feel" between when the towman is pulling on the line
    and the pilot is still holding the sailplane in his hand- the pilot can
    hardly feel any pressure but and the towman end he is really pulling
    like heck on the reel!  Hence the pilot doesn't think there is enough
    "pull" to launch the plane, but will he be surprised when he lets it
    go.  All of our launches(Gnome and Chuperosa 2-meter) were vertical
    with incredible altitude.  Please let me know your results if anyone
    tries this method.  I am entering my 4th year of RC soaring and have
    not been this excited about the hobby in long time.  Best of all it
    is cheap and simple!  Good luck!
    
    Regards,
    
    Jim

	When I first started into aeromodelling with the free-flight
	'Der kleine UHU' from GRAUPNER, towing was _the_ method of
	launching. Later on, I had a rubber hi-start with a spun rubber
	(rubber protected from UV and hitting stones by thread spun
	around it). This reduced possibility of stretching (only about
	160 % of original length while tubing might stretch about 300%).
	Later on, a friend and I came back to the hand-launching method.
	We had the GRAUPNER hand-winch and the GRAUPNER spool. I think,
	both parts are still available from GRAUPNER, but can't confirm,
	I don't have the current catalogue. You can find it in the one I 
	left with DECRCM. The spool has a black reel and a yellow handle. 
	The handle can easily be opened to put the spool on and off the 
	tow line at any point. The winch is not meant to winch the plane
	up, there is a high gearing in it and you would never be strong 
	enough to launch a plane with it. But if you have a parachute
	on the line, you can pull the line it before the chute hits the 
	ground.

	We liked this hi-start method a lot. And it has a bit more to do 
	with 'sport'. You need to define some signs to communicate (hand 
	signs for 'ready', 'go' etc.). The other thing we found to be nice 
	and helpful: You can abort the launch if the glider breaks out. 
	Just throw the winch (or spool) away, and the tow hook releases, 
	the glider is free and controllable. But the running guy needs to 
	have an eye on the glider.

	Greatest disadvantage from my point of view is that you NEED
	company to go flying, but you don't really HAVE company since
	you are quite a distance apart, and as long as there are only 
	two people out, they can never fly together (there can only
	be one plane in the air). 

	But it's great with a big group. I once attended a contest when
	I still was quite a beginner. I had a 1.60 m plane and knew the
	load it gives (BTW the load doubles if you use the spool). 
	Another guy asked me to launch his 3-m ship. That one went up 
	great, but boy, did it pull. I was very careful not to tear it 
	apart. And then the crowd started to shout: "Get your wooden leg
	off and RUN!!!" I thought, well, it's your fault when I break it.
	But it didn't break. The loads are really impressive.

	Good luck with this oldes version of hi-starts. If I can support
	you with GRAUPNER parts from Germany, please let me know.

	Best regards,

	Hartmut

    Kay and I will be trying this at lunch today. Last night I took a 
    large plastic wire spool and put a frame and handle on it. We'll be out
    flying at lunchtime and I'll give it a try. The spool is from the Radio
    Shack 16 gauge wire (100') and is about 2" wide and about 3" deep. Solid 
    plastic so I don't think it will cut off the sides. I only put on a
    single hand hold so it might be interesting if it gets as gusty as they 
    predict.
    
    I like the clothesline pulley idea. All you'd really need would be a
    1/2"-3/4" dowel to slip through the frame. I might try that next. Gee,
    I've got this 13 year old son that wants to go flying with me all the 
    time... ;^)

    Well, I'm getting turned on by all this, don't know why it took
    me so long to decide to try it. Saturday I'll be trying it with
    the 300 ft. of 50 # line on one of my hi-starts. That should be
    long enough to experiment with, and will make up a longer line
    later. My hi-starts are made from coffee cans with 14" dia.
    masonite side plates.
    
    Hartmut or Jim, if you could enter the Part # for the Graupner hand
    winch, I'd sure appreciate it. 
    
    The reason for the high gearing on the commercial units is to allow
    rapid rewinding of the line after launch, as Harmut stated. This
    is required in competition as 3-5 people launch at the same time
    in normal F3J contests.
    
    Terry
    

RE:  Note 399.462 by ELMAGO::TTOMBAUGH
>> Hartmut or Jim, if you could enter the Part # for the Graupner hand
>> winch, I'd sure appreciate it. 

    I have the Graupner cataloge that Hartmut left here for general
    DECRCM use.  Since I can't read German, I have to just look at the
    pictures and guess which description goes with each picture.  With
    that disclaimer said, here is what I found in the 1988 cat.:

    Page 430.  appears to be a plastic pulley with plastic handles.
        "Hochstart-Umlenkrolle  Best-Nr. 1362  "
        Part number 1362 is 9.80 marks (1988 prices)

    Page 431. appears to be the high start spool with winder that was
        mentioned in earlier note(s)
        "Hochstartwinde  Best-Nr. 281 "
        Part number 281 is 47.90 marks (1988 prices)
    
                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    Kay couldn't make it but Lamar Phillips and I went out. It was so windy
    that the histart was fully stretched the entire launch. We didn't try
    the hand towing due to the unpredictability of the wind. Maybe later 
    this week if this gorgeous weather persists.
    
    How about this:
    
    
    plane------------------\
                            \
    modeller                 \             reel
                    stake-----==============o-------------------------stake
                                               ^ highstart rubber ^
    
    
    Sorry, the best I could do with the graphics. What I'm wondering about
    is a version of the hand tow for the solitary flier. Have the spool 
    pulled by the highstart rubber instead of the second person. I have
    some hefty rubber that would pull pretty well and I'd mostly be
    interested in launching smaller stuff (HLS, 2-meter) I fly from some
    smaller fields where the length is a big factor and I'd get double the
    line movement at the plane for the same amount of rubber (I could use
    25' of 3/16" rubber and more line) The other possibility is using a
    standard highstart with a turnaround reel upwind and the rubber
    stretched back downwind. Probably more of an issue with ground snags 
    there.
    
    Just trying to get more omph out of the upstart size fields (which are 
    right down the street from home ;^)

Thanks, Dan for the numbers and prices of the GRAUPNER winch and spool.
I am sure you found the right items since even the prices sound about right.

I would assume that the prices aren't much higher now, somewhere around
DM 50.- for the winch and DM 10.- for the spool. 

If you are interested in these parts, I can try to dig them up here. A friend
of mine is going to SHR in two weeks, so I might even be able to deliver the
parts before christmas...

Send me mail if you're interested, and I'll see what I can do.

Best regards,
               Hartmut

P.S.: Current exchange rate is about 1 $ = 1.47 DM.

    This weekend I tried hand towing 100" gliders to see if it would
    work as well as the 2-meter experiment last weekend.  It indeed
    works well.  The conditions were wind 15+ mph steady with gusts
    over 20 mph.  Was able to tow my father's Gemini ballasted to
    67 oz. without any problems. My Apogee (42 oz.) also was very 
    easy to launch.  The new hand winch made from a clothesline
    pulley worked much better than a high start reel.  I will be
    attempting to tow a 3-meter glider the next time(might be april
    the way the weather is going!).  
    
    
    Regards,
    
    Jim
      

    Another club member and I tried hand towing his G.L. this weekend.
    We used the line looped over the hi-start drum method.
    5 attempts, 5 failures. Comclusion: At 5500ft. altitude, and 0-5
    mph wind speed, which is when we do 90% of our flying, hand towing
    is a chancy proposition unless we can devise a method for instant
    accelleration over the first 3 seconds. For now I think we'll pass
    on this method.
    
    Terry
    

    re: .468
    
    Terry,
    
         What type of ship were you attempting to launch?  Without
    wind, I imagine you have to run pretty hard to pull up a heavy
    glider.  My two experiments have occurred in pretty strong winds.
    Using a bonafide pulley with a handle helps a lot also, which I
    found out this weekend.  In no wind conditions I have gotten 
    terrible launches from high starts with my larger ships.  For
    instance in dead air my 60oz. Paragon from a magnum high start
    would often only gain about 150 ft.  I have been to thermal
    duration contests, where the geometry of the field would not allow
    the 12 volt winches to be set up directy into the wind, resulting
    in some pretty lousy launches.  I hope to get a chance to try a
    dead air launch in the near future, I'll let you know how it goes.
    
    Regards,
    
    Jim

    I was at the library looking through some earlier issues of Model
    Airplane News and noticed an Article by John Lupperger about his
    experiences with hand towing(Oct.'90 issue).  He was very enthusiastic
    about it.  He towed a variety of gliders including Gnome 2-meter,
    Gnome 3-meter, and a home-brew foam and glass 2-meter ship on a day
    with winds 7-10 mph.  His experience was similar to mine in that he
    felt the towman could easily break the wings if he wanted to with
    winds in this range.  There is also a picture of an English-produced
    hand winch which he may be importing for sale.  I would like to hear
    anyone elses experiences with this method.
    
    
    Thanks,
    
    JIM

    I had the chance to hand tow two 100" gliders(Mirage&Apogee) in calm
    conditions this weekend.  My first three attempts all failed.  The
    reason was timing and release technique by the pilot.  In calm
    conditions the pilot must not throw the glider out away from him
    because it will simply fly off it's towhook before the slack is taken
    up by the towman.  No, you must push the glider upward as the towman
    begins his run.  Once we got the timing down the launches were great,
    much better than could be obtained with a high start.  So a little
    practice is in order to make this work in calm conditions.  To improve
    the situation, I have added another pulley(a high start reel spinning
    freely between two, 3/4" pieces of plywood screwed to a 2x8).  This
    increases the mechanical advantage from 2-to-1 to 3-to-1(ie when the
    towman moves 10 ft. the glider moves 30ft).  I will report on the
    effectiveness of this system when we get another decent weekend.  I 
    feel I should now be able to launch any sailplane in any wind condition
    easily to a height of 600+ ft. for a total investment of less than $20.
    With the addition of the second reel, the towman now "runs" toward
    the pilot/launcher vs. away from with the single pulley method.
    
    
    Regards,
    
    Jim

    Keep the info coming Jim.
    
    I'm watching with great interest. I haven't had the chance to try my
    hand at it yet but you results do bode well.
    
    A couple of advantages that I see in this two pulley method are that
    the towman can keep an eye on the plane and the overall length of the
    field can be used (since no room for running needs to be set aside)

    re .476
    Jim, do you have the 2X8 fixed in the ground with one or more pulleys
    attached to it, and the towman stands between the 2X8 and the pilot?
    This is the only way I can visualize this if the towman runs toward
    the pilot on launch. Whatever you're doing, it sounds like it works.
    
    Terry
    

    
    
    
    
    
    
                       _______________________________________-->to glider
 highstart reel->    |(O|
 3/4"plywood ------> | \|___________________                 
                     |  |        ----------O)-> Towman with handwinch
                   __|__|_______/_
                   |______________|  <--- 2x8 board secured into            
                                          ground with pegs
    
 Please excuse this poor attempt to display the two pulley method I
    discussed.  The line is fastened to a screweye at the front of
    the 2x8, it is then looped around the towman's pulley and then
    back around the highstart reel which is doweled between 2 pieces
    of plywood, allowing the reel to spin freely.  The towhook is
    connected to the glider.  The towman runs toward the pilot, 
    causing the glider to rise with a 3-to-1 advantage.  Jim Reith's
    comment about being able to use the whole field available is right
    on the money.  I was so frustrated with high starts blowing into 
    trees and across roads that I spent $300 for an electric glider.
    I am now able to fly my regular gliders to a 600 ft. launch  without
    pulling a shigh start out 900 ft.  Two methods work to reduce 
    the effect of crosswinds on the parachute after it has released.  The
    first is for the towman to keep running forward after the chute is
    free, this pulls it rapidly to the ground before it can drift into
    the trees.  The second method if you have a lot of guys around is
    to connect a fishing pole with spinning reel to a clip about ten
    feet from the towhook and simply reel the line back to the launch
    spot for the next flyer.  This is a poor man's retrieval system!
    But it works great because the chute will fall slowly if the towman
    stops running after the glider is off, giving time to reel the towhook
    in before it drifts into the trees.
    
    
    Regards,
    
    Jim

    Thanks Jim, now I get it. Your method would be illegal for F3J rules
    as presently written, but it is actually more efficient.
    
    Terry
    

I think you could replace your 2x8 with a standard dog run anchor
which has two eyes on it.  One standard and the other is the handle.

At the soccer field we use there are big posts by the edge of the
road every 10 feet or so.  We could anchor to one and loop thru
the towman pulley back to a second one with the turn around pulley on
it.

It would seem that to properly use these pulley arrangements and not get out
line tangled up in them we need some thicker line - that is not
monofilament fish line - what do you think?

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    I don't think you'll need heavier line since the maximum force will be
    between the plane and the 1st pulley and you still need to worry about
    folding the wings. You will need to make sure that the line is on the
    pulleys so it doesn't get caught/frayed against the pulley axel.

>    I don't think you'll need heavier line since the maximum force will be
>    between the plane and the 1st pulley and you still need to worry about
>    folding the wings. You will need to make sure that the line is on the
>    pulleys so it doesn't get caught/frayed against the pulley axel.

I wasn't thinking of force - just thickness to help prevent exactly what
you said - getting caught against the pulley axle.  Monofiliment tends
to form loops rather than just go limp when ever you accidentally let it
have some slack.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    The two pulley method is a nice idea for making the most efficient use
    of available field space. But I kept thinking about the "3 to 1"
    advantage, and I believe it's really 2 to 1. If you imagine the towman
    walking AWAY from the pilot an equal distance instead of toward him, you 
    will see that the plane gets towed the same distance. Great idea, tho.
    I'd like to try this towing business some time, sounds like a new
    adventure.
    
    Dave    

    I did the paper strip exercise and it is just 2x since you only get
    double the distance to the towman. Three pulleys with the towman having
    two of them would give you 4x but the pulley needs to be moved in order
    for it to multiply the effect. The second pulley DOES make it able to
    be used in smaller fields since the towman is moving into the field
    rather than away but it just acts as a turnaround since it doesn't move
    relative to the ground stake.
    
    Paper exercise:
    
    Take a strip of paper and mark it at regular intervals. Mark a sheet of
    paper with the same intervals to be used as "the field". Tape the
    ground stake down onto the field and use pencils as the pulleys. Move
    the towman pencil 1 unit and the end of the strip (glider) only moves 2
    units across the field.

    I will have to dig out my physics books to verify the mechanical
    advantage of the pulleys.  Empirically the advantage of the 2 pulley
    system was approximately 3-to-1.  I set the actual system up on my
    work bench with a 4 ft. rule to measure.  When the towman's reel was
    pulled 12 inches the glider(a wingnut tied to a piece of string) moved
    33 inches.  We then repeated the experiment with a single pulley, and
    found that a movement of 12 inches resulted in the "glider" moving 24
    inches(2-to-1).  I will verify this theoretically.  I am using 80 lb.
    monofilament line which works very well.  There is an article in the
    November-December issue of the NSS publication about handtowing and
    a handtow competition that took place this summer somewhere in the
    midwest.  The conclusion was that monofilament line worked much better
    than braided line.  It stretches and consistently higher launches were
    achieved using it.  They claim 40lb. line was used with the 2-meter
    ships without a problem.  Terry's comment is right on about the 2
    pulley system violating F3J rules which allow only 1 pulley and 150
    meters of line.  But for launching my 4 meter Algebra, I think it is
    the way to go.  In the sixties my father's full size glider was
    launched using this method with an automobile.  He verified that using
    2 pulleys the tow car was driven at approximately 20 mph, resulting in
    a 45 degree tow of the glider at 60mph.  He showed me a letter from a
    soaring club in Ireland that was using this method an claiming launch
    heights of 3200 ft.  This is a good alternative if you do not want to
    make the investment in an electric winch.  I tallied my investment in
    this sytem, all was made from parts I had or available at the hardware
    store:  handwinch made from clothesline pulley $7.00 +  stationary
    pulley made from high start reel $7.00 + 600 ft. of 80lb. fishing line
    $7.00 = $21.00.  My magnum high start(the smallest one) cost $75.00
    and will not launch my 2-meter ships well because they weight of the
    rubber is too much, it does not launch my 4 -meter Algebra well unless
    there is adecent breeze which I can line directly up in an pull back
    800 ft.  The heavy high start is also not easy to manage when you are
    alone.  Hope to report on the performance of the 2 pulley system soon.
    Winters in upstate NY are unpredictable, we could get snowed in
    anytime.  They are already skiing 1/2 mile from my glider field.
    
    
    Regards,
    
    Jim
    using an automobile 

    Got a chance to try hand towing yesterday. It was windy but we tried it
    with a Chup, Gnome and Gentle Lady. The tow was done using the line
    from my upstart pegged into the ground at the ring where the rubber and
    line join. The biggest problem I found was getting enough initial
    tension for the launch to feel "safe". I used a single pulley made from
    a Radio Shack wire spool (2" wide and 4" deep) and didn't have any
    problems with it. I used a dowel through the center for an axle and two
    pieces of closet pole for spacers/handle. I founds that initially I
    needed to walk back briskly but then as it passed 30 degrees to the
    ground I found that the wind made me walk towards the stake to lessen
    the pull. We got several good launches with the Chup and without the
    need to stretch back the rubber, Kay could land at his feet and  go
    right back up the line. It gave him an excuse to try some aerobatics.
    The Gnome and Gentle Lady were really pulled by the wind and they
    needed to have more give in the line to tow properly. Both popped off
    and blew down wind (and I won't explain why the afternoon was spent in
    a swamp) but the damage was minimal. I think they need a farther
    forward tow hook position for the hand towing to work well. They tended
    to be very skitish on the line. Next time I hope to be the reciever of
    the tow but it was interesting to do and will be interesting to try in
    less wind.

    Thanks to all who provided info. on fishing/kite line.  That's what
    makes this conference so great!  
    
    RE: -1
    
    Jim,
    
       I have experienced a much greater incidence of popoff's since
    we have begun hand towing.  I think the reason is because you are
    climbing much more steeply than when using a high start, and there
    is always considerable tension on the line.  We are not popping of
    as much as we become more experienced with this method.  You can
    also get great zoom launches if you are in sink with the pilot.
    This becomes easier using the two reel method as we are now doing
    because the towman and the pilot are standing next to one another
    and can converse in normal tones.  You were right about the two
    pulley method giving only a 2 to 1 advantage.  I have devised a
    3 to 1 system using two pulleys, which I will elaborate on if anyone
    is interested.  
    
                                                Merry Christmas,
    
                                                Jim
    
    

>    pulley method giving only a 2 to 1 advantage.  I have devised a
>    3 to 1 system using two pulleys, which I will elaborate on if anyone
>    is interested.  
    
We're all interested Jim - elaborate away!

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################
    
    

    I hadn't considered pulling out enough line to get the towman back near
    the pilot in the 2-pulley case. I'd be interested in the 3-to-1 2
    pulley case from a physics standpoint. How did the Spag's line work out
    (since I'll probably be using that myself during next season)? Neat
    stuff. I can now see where the hand tow launches would be significantly 
    higher than a full-field high start in small fields (like I have 5 minutes
    from my house ;^) The "chute" dropped the line right back at the launch
    point so we got more launches in an equal amount of time since we
    didn't have to walk back stretching out the rubber.

    I just thought of the 3-to-1 case! the towman is heading away from the
    pilot again. The towman has the ground stake end of the line and 1
    pulley and there is a turn around pulley staked in the ground. The line
    goes from the towman to the stationary pulley back to the towman pulley
    and up to the plane. Towman motion pulls three lengths of line, to and
    from the stationary pulley and to the glider! 3x but heading away from
    the pilot...
    
    I like the towman near the pilot situation better because then you can
    talk and swap tasks without walking the length of the field. That way
    everyone can take turns towing without having cross field relay races
    ;^)

    As Jim eluded to a few notes back, I'm the reason we had to venture
    into the swamp yesterday afternoon. To find out more about it, read note
    1218.52(it's kinda of long.) I can't wait to try the hand towing technique
    again, but next time with a little less wind!

    -Lamar

I'm trying to read all of 399.*, and got diverted to this note.

Are you folks still using the hand tow method?  I'm thinking about
getting in to the sport, and anything that saves me money in the
begining sounds like a good idea :-)

I had one additional thought about the 1 vs. 2 pulley system.  The
other factor to consider is that the tow line anchor point (by anchor point
I mean where the tow line leaves the earth, not where it is staked in)
is stationary in the 2 pulley set-up.  Also with the 1 pulley
system the length of line in the air at the begining of launch
could be less (since with the 2 pulley system the length of line
in the air at launch would be the entire length of the field.)

Although the 1 pulley = 1:2, 2 pulley = 1:2, & 3 pulley = 1:3 formulas
are good approximations, they probably do no fully reproduce the
dynamics and influence of the change in location of the anchor point
and the glider during launch.  From what little I know of sailing,
the most 'push' comes not when the wind is going in the same direction
as the boat, but at a fairly good angle (90 maybe?)  The same things appears
to be happening right before release when zooming occurs on a winch.

This all said, I've never seen a glider launched and basing all of
theorizing on seat of the pants feel from kite flying!  (Looking forward to
seeing RC gliding, now that I am on Jim Reith's dist. list.)

-Dave

    I've still got the hand towing gear at home but we haven't been (bored,
    cold, etc) enough to use it recently. It's generally easier to run out
    the upstart in acton and have at it. The hand tow launches seemed
    higher because the pull was more uniform and you could let out the
    reeled in line when kiting conditions prevailed. The most benefit is
    seen on calm days when the stretch goes out of the rubber before the
    glider tops out on the launch.
    
    The launch is somewhere between a winch and a highstart since the pull
    doesn't quit until you want to get off. We never tried the two pulley
    system where you could be positioned down near the pilot.

    I ran across an interesting exerpt describing how a group from
    Italy launched their planes at one of the European F3J meets
    this year:
    
    "Line-speed amplication schemes can be carried to extremes.  It is
    reported that the Italians strongly influenced by F3B, showed up at
    least one contest in Europe this Summer with a 5:1 pulley arrangement
    with two large and strong men towing.  With this setup and a little
    breeze, end airspeeds of 80 to 100 mph are within the realm of
    possibility.  They were attaining 300 meter launches(almost 1000 ft!)
    in almost calm conditions with F3B style ships."
    
    I read some of the German entrants did the same thing.  0-1000 ft.
    in about 5 seconds is pretty impressive performance by any model
    airplane standard.
    

    Jim,
    	I've not come across the 5:1, but even at 3:1 with strong chaps its
    almost impossible to get any movement from the tow men.
    
    In Europe during the interglides, a number of competitors were using a
    straight turn round with one end deeply spiked in the ground and two
    men in "horse like" harness round them pulling the turnround. This gets
    the moulded models to between 600-800 ft.
    
    Trev

>    possibility.  They were attaining 300 meter launches(almost 1000 ft!)
>    in almost calm conditions with F3B style ships."

Sounds like winch wars all over again.

Makes you appreciate the good old Hi-Start and a Gentle Lady.

Bye          --+--
Kay R. Fisher  |
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