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  • #31
    True the additional clearance to insert a Z bend in the hole would not matter that much on a tow release since either it does or doesn't. But when I see them being used on aircraft for controls like the elevator and ailerons I cringe. Probably my OCD kicking in again. I just saw it as a good segway to discuss control linkages and a little about servo set-up.

    OOH, another good point about horns on servos. I try to have the rod to hole lateral lines form as close to a 90 degree angle as possible when at center. This prevents mechanical differential to be introduced in the linkage system. Many know this, but I have seen many aircraft with it on controls like the rudder, not good IMO.

    Sometimes I intentionally set up the linkage with mechanical differential though such as flaps that are used for glidepath control with inboard aileron mixing where one needs more down than up. Just all good setup tips that should be used on every airplane. However, computer radios have allowed many to get lazy by punching in some numbers and not take that care in their installations.

    Most of what I mentioned applies to what we have learned flying our very thin wing competition gliders on monofilament lines. F3J is a class that has a 100 meters to the turnaround pulley line length , here half of which is mono on a winch, at the World Championships it is all mono towed by two strong quick people. F3B is a class where the line is 100 meters all mono on a winch. Monofilament when under tension can store a great deal of energy!

    For those that fly in these classes many try to have all of the push rod linkage internal to the wing, which results in a very short horn set-up both on the servos and very short ones on the surfaces. This requires precise sizing of the pivot point holes. I use a #53 number drill for this and after the clevis pin is inserted and the horn rotated by hand a few times it is a snug rotational fit. If there is any slop in the control system then flutter can occur in the dive and pull out when releasing from the line to gain that extra energy. Not pretty as many airplanes have been destroyed that way... VNE reached rapidly on that airframe!

    An amusing comment I remembered last night relating to trying to transpose 2D into 3D in one's mind. Shortly after hiring in at the company where we modified aircraft I was on the manufacturing floor supporting one of the assemblers about a plan I had composed. He mention he had to stop work on the assembly and wait for an engineering change as the parts would not fit together. The engineer came down and saw the assembly for the first time in 3D and said when looking at it, "well it worked in CAD." Remember to honor our Veterans today.
    Mark

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    • #32
      Mark to this day I have never had a E-Z connector fail. But there's always a first time. No doubt when I build the Cherokee RM 3rd scale next year I won't be using E-Z connectors at those loads from the large air frame. But I could start practicing the discipline now on my current K8. She's a 118 inch span and 5.5 pounds.

      So what you are suggesting I'd like to see. One or two or maybe even three pictures can speak volumes. From what I'm reading you don't use the long arms but rather the wheels? It would just help me to see it. I don't air tow for the first time until Dec. 14th (weather permitting) which gives me time yet.

      BTW I never forget. Three years ago I went to Normandy, a sobering affair that brought tears. I was so glad to go there and pay my respects. It was on my bucket list.

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      • #33
        What did the French diver vacationing in America, who had decompression sickness, tell his friends he had who were visiting him in the hospital?

        'Zee bends!' Sacré bleu!

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        • #34
          OK. Stop that. You're being silly. LOL!

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          • #35
            Steve, please understand I'm not ignoring you. My club and I have offered to help Reto Fiolka a club member and other people from the USA decide who will go to the next RC Sailplane FAI F3B Worlds Competition representing the USA next year. I will be very busy all day for the next four days. It requires the airplane to fly three different tasks essentially unchanged. The only thing the pilot can alter is the weight and wing camber which must be done via the radio of the aircraft, actually a very complex series of tasks. I posted a link to the US site below.

            Mark

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            • #36
              Thanks Mark no problem. Thanks for the link.

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              • #37
                My friend Bob Martin came up with this for RC Submarines which I also enjoy. It could work well with the release or has this already been done? Here's one of my subs. 66 inches long scale model of the Nautilus.
                Exceptional scale models, accessories and RC components with a focus on military, sci-fi and fantasy submarines.

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                • #38
                  Steve, had time this morning to post a few pictures on my Ka-8 radio installation. Look them over and note how it looks. I had to put blocks under the servos because there would be too much friction on the rod into the housing otherwise. I had a thought when looking at the installation one could eliminate more parts (2 by my count) by using two smaller servos for the elevators instead of the domino joiner as Pheonix calls it. That might be a tight squeeze, but there are some mighty strong small servos out there. Also, the nice thing about using another servo is you also eliminate all the tiny grub screws which have a propensity to loosen.
                  Last edited by Mark9; 11-15-2018, 01:33 PM.
                  Mark

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                  • #39
                    Mark I'm OK with the single full size Futaba 3003 because I took the precaution of using Stay Brite silver solder to join the two control rods which BTW are dead on to the servos. One of the things that Seagull got right. But the release servo I am going to change as recommended. Thanks for the pictures and very clean and nice install Mark. Bravo.

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                    • #40
                      Stay-Brite is great stuff. Off to the field.
                      Mark

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                      • #41
                        I was starting to put a tow release in my big Sinbad when I was warned that if it didn't have ailerons it would be unsuitable for towing. Shes only rudder and elevator.

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