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Aerotow Trainer Sailplanes

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  • Aerotow Trainer Sailplanes

    Two Sig 'Riser' sailplane kits are being modified as aerotow trainers. Construction of the air frame is done with one. So far, it weighs 705g with two regulators, four Hitec 55 'Feather' servos, receiver battery and JR DS368 release servo. The fuselage of the second is finished. The other will get completed as soon as the first proves airworthy enough! The wings were 'straightened out' in lieu of the polyhedral design and strip ailerons were fashioned from the kit's TE. A retracting 'pin-in-slot' release was built into the nose. The tail feathers and wing tips were rounded... just for fun... and the rudder has pull-pull control. Spoilers were contemplated then dismissed because I wanted these to be very simple flyers... and I was lazy! Hopefully some interest will be generated when the 40 glow trainer tow plane and these are brought to the field and flights offered.

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    Thanks to Joespeeder in Michigan for the idea! He had a couple of small sailplanes for folks to try out at Frankenmuth. Wish me luck!

  • #2
    Absolutely great idea Mike. We did this back in 2010-2011 with an Easy Glider and a Telemaster 40 powered with an OS .52 4-stroke glow engine. Dozens and dozens of pilots had their first aerotow experience with it.
    A Site for Soar Eyes

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    • #3
      Easy Glider is a great trainer and solid performer in light lift. I like those Risers too. Might take the air balance section of the rudder off though, or beef it up to prevent flutter on tow.

      Comment


      • ARUP
        ARUP commented
        Editing a comment
        Thanks for your concern! Hopefully, high speed towing will not be done so we can only hope flutter won't be an issue! The kit is designed with a rudder like this. I merely rounder the corners. At least the loads on the Hitec-55 'Feather' servo will be reduced. Hard points were added to the fin and stab so they can all be braced together in case a hard landing causes the fin to break loose. It is poorly designed IMHO. I 'doweled' the fin's LE to the bottom edge that is glued to the stab and have some large-ish gussets in there. Flight testing will commence as soon as nice weather arrives. It rained all weekend.

      • Mark9
        Mark9 commented
        Editing a comment
        Mike, I agree with Victor. Many of the early thermal ships had a balanced rudder and they were quite prone to flutter, even at normal flight loads. Eliminating the aerodynamic balance is one mod most do to eliminate the problem. Word is that the servos at the time were to weak and needed the help. Also, talking servo power the HS-55 is pretty small and may not be up to the task. Are they 100" or 2 meter? If they are the 100"er I would go with stronger servos on both flight functions the nose weight will be required anyway. Let us know how it goes. Great idea to get people involved.

      • ARUP
        ARUP commented
        Editing a comment
        They are 2 meter airplanes. We'll try 'em out and see what happens! The tow plane is powered by an Enya 40 2 stroke that has a baffled piston so not a lot of power there!

    • #4
      Hi Mike,

      Cool project !

      Thanks for the shout out. We've found trainer aerotow sailplanes very fun and interesting. Some things you'd expect and lots of surprises in getting lots of aerotow 1st timers into the air for their first tow.

      Thanks to the Ka8's, we had 2 sport pilots that added balsa sailplanes to their fleet of rc aircraft for last years event. I know we generated interest in some of the DLG guys and I'm betting some will add an aerotow plane to their lineup from the exposure they got to aerotow at the event.

      Plus, thanks to our event the Frankenmuth Aeromodelers have generated lots of interest in sailplanes in general and now are flying sailplanes on Wednesday mornings.

      They have a group of guys that are learning to thermal and really enjoying the change from power. Electrics and winch launch mainly but if I could get up there I'm sure we'd do aerotow as needed.

      I'm really a carpet bagger up there. They are very kind and excited to see the aerotow event grow each year.

      Keep us updated on your progress and how the trainer works out.

      Joe
      Last edited by Joespeeder; 10-15-2018, 08:30 PM.

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      • ARUP
        ARUP commented
        Editing a comment
        If they survive I'll bring 'em to Frankenmuth next year! That was fun!

    • #5
      Mike, when we were using the Easy Glider trainer, we found the HS-55 servos were plenty strong enough for the flight loads, but not the abuse of the landings (cartwheels, tree branches, etc.). They were replaced with HS-65HB servos and no more problems!!!
      A Site for Soar Eyes

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      • ARUP
        ARUP commented
        Editing a comment
        Thanks, Jim! I have a bunch of these so when they get all busted up I'll replace them with the ones you mentioned. I plan to bring the extra 55s with me during any outings just for that purpose!!! I don't know how I ended up with so many of these 'Feathers'! Must have ten more in a box besides the ones I'm using for these two birds

    • #6
      What a great idea !!!

      Not that its earthshaking but that it is a basic and quick (relatively) aerotowing solution to fun fly sailplanes or introduce existing flyers to something *non-competitive* oriented.

      After seeing this thread i ordered a sig riser 100 kit and will make the modifications to have a tow release, ailerons, spoilers, undo the balanced rudder,
      and round out the flying surface's tips just as seen above. Got to have the fixed wheel too - just have to........

      To tow this Riser 100 locally ( and my just finished 1/4 scale hall cherokee) i have assembled all the bits and pieces to complete a stock H9 81" Ultra Stick.

      No doubt i will take it to regular aerotows in 2019 with a buddy box for others to try.

      john s. in so. calif.

      Comment


      • ARUP
        ARUP commented
        Editing a comment
        I toyed with the idea of a wheel and spoilers but decided to KISS! I'm keeping the rubber band-on wing just in case of a ground loop at take-off. I fully sheeted the 'D' tube. I reduced the dihedral in the main joiner. There is ample material in the kit for this. Way to go Sig! I love Sig! One sailplane has kit wing plan form which is double taper and the other has a straight LE root to tip. The first one with the double taper has a little built in wash out. The one with the straight LE shouldn't need it. I just laminated a bunch of spar joiner 1/64" strips to 'fit the bend' of the spars for the straight LE one if that makes sense.

        The H9 Ultra Stick will have more than enough vitamins to pull the Riser!

      • ARUP
        ARUP commented
        Editing a comment
        Joe- if the group build these it is really a simple matter to flatten the wing and cut ailerons from the supplied TEs. You might let them know RES polyhedral models can get towed but it's a little dicey! 'Full house' control is better.

      • Joespeeder
        Joespeeder commented
        Editing a comment
        Thanks Mike, I'll ask about adding those changes. Gino is the one leading the charge up there and he's really happy to have more thermal hunters in the mix. I get the sense these are going to primarily to fly on their Glider Wednesdays. If it were me, I'd build mine as you described but it's a great 1st step either way. I bet we'll see a mix of props and winch launch set ups. If I can agitate Gino a little maybe we can get some aerotow Risers in the mix?? lol

    • #7
      Small update -11/12/2018.

      the sig 100 kit showed up just fine last week and i am planning on starting on the H9 big ultra stick this week.

      getting all the Stick power plane bits and parts was kind of a never ending shopping dirge as i hadn't done a non-glider power plane in donkey years.

      the fundamentals of model e-power are already with me so i don't have to sweat that. fyi - why electric power ? have an unreasonable aversion
      to IC motors after dealing snarling Cox TD engines as a kid and hacking my fingers to bits on those props - that nitro fuel still stings in my mind

      building the riser kit will be a no-brainer so maybe the new two plane package and first tow flight will be done by Christmas time (.....2018....)

      js

      Comment


      • Mark9
        Mark9 commented
        Editing a comment
        Yeah, no goop to clean off afterwards either using electrons.

    • #8
      Alright!!!!
      Looking forward to watching the progress.


      Len Buffinton
      Team Horizon Hobby

      Comment


      • ARUP
        ARUP commented
        Editing a comment
        I'll second that... let the fun begin!
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