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First time aerotowing...what I need to know

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  • First time aerotowing...what I need to know

    I'll be heading out to Visalia Ca. at the CVRC filed in Dec. I have been flying gliders to jets since 1985. But I am new to towing and need to know what to expect. I know how it works on full scale glider towing and have many hours on the simulator.

    But I need to know the procedure for RC. I have been told I use ailerons only to keep in line with the tug. To stay at the same altitude as the tug with elevator. I don't know much more than that.

    I'll be using my Seagull Models 3 meter Ka8-B to train on. She has a nose tube and internal servo loop release. The weight of the K8 is 4 pounds.More likely 5 pounds once I get the plane balanced.

    I need all the ground school I can get before Dec.

    Thanks so much for your help.

  • #2
    Hi Steve,

    As you know from full-scale, staying in correct position behind the tow plane is critical. In order to allow more leeway while on tow, R/C tugs typically attach the tow line to a point on top of the fuselage a bit forward of the trailing edge of the wing. This allows the sailplane to make wider excursions without getting into too much trouble.

    Because of the tow line location on the tug, the ideal position for the sailplane is directly behind and slightly above the tug. Mostly, very little control input is needed to stay in position. Slight finger pressure up or down on the elevator and slight aileron input to keep your wings level is all it takes. Here, the "less is more" expression applies!

    Typically, tug pilots try to make shallow banking turns, but once in a while a sharper bank is necessary. Resist the temptation to bank too steeply while on tow. Banking too steeply can allow the sailplane to turn inside the flight path of the tug and cause the tow line to go slack. Better to keep the sailplane wings more level and allow the tug to pull you around the turn like a water skier behind a boat.

    Communication with the tug pilot is important. Let the tug pilot know how high you want to go and when you would like to release. Remember, you are the one who controls when you release. Let the tug pilot know when you are ready to release so that both planes can level out and maintain a heading. Call out the release and both pilots should stay in line until the release is verified by seeing separation between the two planes. If either plane assumes a clean release has happened and then turns away sharply, disaster can follow!

    Most sailplanes of the type you will be flying naturally want to be in a high tow position behind the tug and may even need finger pressure down to avoid getting too high behind the tug. They also tend to pitch up upon release, so be expecting to see that. It is sort of like what happens when you come off a high start or winch launch.

    The most dangerous part of the tow is right at the start. Make sure your sailplane is right in line with the tug. If your sailplane tips to one side and catches a wingtip, be ready to release. Failure to immediately release can allow the sailplane to be whipped hard to the opposite side and go inverted...very bad thing! The smoother the runway surface, the less likely this will happen. Back east, we mostly have grass surface runways. If the grass is too tall, thick and/or wet, takeoffs can be very tricky. Again, as for control input at the start of tow...less is more!

    Okay, that is my $0.02!
    Last edited by JimD; 11-08-2018, 09:07 AM.
    A Site for Soar Eyes

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    • #3
      Steve,

      I started aerotow about three years ago, so that first take off is still fresh in my mind. What Jim has said is all true.It takes very little effort on the part of the sailplane pilot during the tow. Keep the wings flat and let the tow plane generate the yaw aspect of the required turns. No other effort is usually required of the sailplane pilot.

      I found that all of my tow ships so far have, except for my 7 lb. 110" Fox, require down elevator during the tow. This is most likely due to the higher air speed compared to normal flight speed and the glider can assume a high position on tow as a result. The tow pilots don't like this because it can cause a down pitching moment to the tow plane.

      If your radio can do it set up a flight mode switch that also controls your tow release. This is my "Launch" flight mode. My radio will allow separate trims for separate flight modes. I have trimmed in some down elevator while in the launch flight mode to help keep my gliders in a much more acceptable position. When activated the glider is then trimmed to stay lower in line and reverts to normal flight trim when I release the line. Just be ready for that additional energy when you release as the glider can pitch up aggressively, especially one like the Kate.
      Mark

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      • #4
        Thank you both so much for your instruction it very much appreciated. It all makes a lot of sense. I would imagine on first flight it would be best to have a experienced pilot with towing take the ship up. Once up I can be handed off the TX and trim the bird. Then on the next flight with a bit of breathing over my shoulder take her up myself. You guys are just great! Thank you!

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        • #5
          Hi Steve.

          The previous posts pretty much cover everything you need to know, so at the risk repeating something or stating the obvious, its important to relax and have fun. One important reminder is to always have your tow loop installed in the glider and the glider turned on and operating correctly before going out to hook up. The loop is simply a string tied into a loop. Common type is masonry string or something of that nature. Most event coordinators will provide loops for the event. Always pack a few in the slim chance there are none there.
          Nobody wants to wait for you to put a loop in while the tug is sitting there running.

          Also, communicate with the tug pilot, its the best way to have a great tow.
          Lastly, I always thank the tow pilot after each tow, its a sincere appreciation for providing me with a lift to altitude. ( and they like it too)

          Good luck, its much easier than you think, but we don't tell people that........

          LEN
          Len Buffinton
          Team Horizon Hobby

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          • ARUP
            ARUP commented
            Editing a comment
            Yes... have everything ready! The loop is the 'weak link' so, in case things go 'pear shaped', you want it to break. The strength of the loop will be determined by experience but it is obvious you don't want a 200lb test loop for a 4 lb glider! Then, after you land make sure the approach is clear, usually a field marshal will let you know, then get your model as quickly as needed and bring it to the pits. Only then should you fiddle with turning it off, installing loops, etc. It sounds obvious but if I land a little too far away (it happens... with me anyway, lol) I get the model and take it off the field walking directly to the edge of runway which is 90 degrees to the landing approach instead of blocking the field by walking directly on the runway toward the pits. Some times fliers stand behind their sailplanes at take off and that's okay. However... don't continue to stand there! Immediately have your spotter 'walk' you to the flight line and stay with your tow pilot until you communicate when you are going to release. The tow pilot will reduce throttle which takes tension off the tow line thus reducing the effort your servo needs to release. Also, I can imagine if you release while tug is at full power the tension in the tow line might make the tow line retract somewhat like a rubber band. Those loops can sure get knotted up! If you release when the tow is at full speed you might get a 'zoom' launch! Another thing to consider is the flight line location relative to the tow pilot station. If the flight line is off to the right of the tow pilot's spot then it is prudent to be on the tow pilot's right. And please walk away from the tow pilot station after release. Get your spotter to help if this isn't comfortable alone. If there are too many fliers around the tow pilot it just gets to be bedlam! This seems like a lot of information but it's really just (un)common sense and etiquette!

        • #6
          Len thanks very much. All common sense to anyone with flight experience but I have never been one to assume anything or think for a moment I know it all. I greatly appreciate all the wisdom I can get.

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