Part 103 Glider Tug designs

Discussion in 'The light stuff area' started by b7gwap, Feb 20, 2018.

  1. Feb 20, 2018 #1

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Hey everyone.

    I'm wondering if anyone here has done glider towing with an ultralight. I suppose the logical next question is "what kind of glider are you planning on towing up?" I bought some ULF-1 plans and am years out from ever completing it, but I wanted to see if any of you ultralighters have done this. Even if you just towed up HGs I'd be interested in:

    What make/model/engine/gross weight the tug was,
    What make/model/pilot weight of glider was towed,
    Terrain and field length, obstacles, etc.
    Techniques, mechanisms (type and locations of releases, line lengths and materials)
    Was it any fun? Too dangerous? Recommend other methods of getting a sailplane aloft? (winches, car tows, etc.)

    Thanks everyone, I love this forum.

    Austin
     
    choppergirl likes this.
  2. Feb 20, 2018 #2

    Victor Bravo

    Victor Bravo

    Victor Bravo

    Well-Known Member

    Joined:
    Jul 30, 2014
    Messages:
    5,401
    Likes Received:
    4,386
    Location:
    KWHP, Los Angeles CA, USA
    There is an ultralight-ish UL glider tug called the Dragonfly, by Bobby Bailey. Very successful towing hang gliders and UL gliders.

    It probably does not meet Part 103.

    To have a Part 103 airplane that is capable of towing, you would have to overpower a Quicksilver and still get under the weight requirement. The Kolb Firefly may do it using one of the modern Paramotor engines.

    Onceyou managed to do it technically, then the legal questions crop up and you may not be able to to using a 103 aircraft. They might argue that it is bordering on commercial use because someone else is benefiting by it,a nd it cannot be claimed as 100% pure recreation. IMHO you'd have an uphill battle. Using an LSA like the Dragonfly may be the shorter and less painful path if you must aerotow. I would look into car tow as the fastest way and the least prone to create an FAA problem.
     
    b7gwap likes this.
  3. Feb 20, 2018 #3

    jedi

    jedi

    jedi

    Well-Known Member

    Joined:
    Aug 8, 2009
    Messages:
    1,662
    Likes Received:
    372
    Location:
    Sahuarita Arizona, Renton Washington, USA
    I agree with VB above. I have been on the receiving end behind a Dragonfly and done lots of Super Cub towing of normal gliders but have not done a for real tow with Dragonfly or WSC but have I have done simulated tows. Weight and power of a 103 tow plane would be an issue but I expect it could be done. I would consider an Aerolight 103 as a tow plane for a hang glider. I do not know of anyone who has done that but you might contact the company and see what they have to say.

    For auto tow the common method is a payout winch and it is much safer than a fixed length line.

    I do not think there would be legal issues as prior towing was done under the 103 training exemption and continues under the LSA experimental caryover.
     
    b7gwap likes this.
  4. Feb 20, 2018 #4

    cluttonfred

    cluttonfred

    cluttonfred

    Well-Known Member

    Joined:
    Feb 13, 2010
    Messages:
    6,198
    Likes Received:
    2,139
    Location:
    World traveler
    Legal issues aside, I would think that any true ultralight that still meets Part 103 weight with something like a Rotax 503 could tow a Part 103 glider: Aerolite 103, Quicksilver Sprint, CGS Hawk, maybe even a MiniMax.
     
    b7gwap likes this.
  5. Feb 20, 2018 #5

    max_burke

    max_burke

    max_burke

    Well-Known Member

    Joined:
    Sep 10, 2013
    Messages:
    110
    Likes Received:
    33
    Location:
    Vancouver, Canada
    What about winch or auto towing? It seems like these could be quite economical. And with auto towing, you can use the same vehicle you brought the glider to the field with!
     
    b7gwap likes this.
  6. Feb 20, 2018 #6

    Twodeaddogs

    Twodeaddogs

    Twodeaddogs

    Well-Known Member

    Joined:
    Jan 18, 2009
    Messages:
    794
    Likes Received:
    228
    Location:
    Dunlavin, County Wicklow,Ireland
    winch towing means you need a powerful engine to haul the glider up and have to pay for the associated fuel burn and maintenance and it is height limited. Using a vehicle to launch a glider has the same limitations, which is why gliding schools and clubs use traditional piston engined aircraft like Super Cubs because they are tough and can cope with abuse and a tough outdoor utility. Towing with microlights is done quite a bit in Europe now as good Super cubs are scarce.
     
  7. Feb 20, 2018 #7

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    5,079
    Likes Received:
    1,241
    Location:
    North Carolina
    There was an Pterodactyl Ascender offshoot with a tow bridle called the 'Ptug'. There is an article online somewhere that I can't find about a guy fitting a 582 to one. Winch tows can be done with a scooter engine/transmission. I gather that 250s are preferred for getting some height. Fuel costs will be trivial.
     
  8. Feb 21, 2018 #8

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    5,079
    Likes Received:
    1,241
    Location:
    North Carolina
    Canuckian hang/paraglider tow manual attached.
    Takeaways for me: Tow speed shouldn't be over 35mph. Initial line tension of ~100lb for 200fpm climb. Max line tension of 210lb. At 30mph, those like tensions are going to need an extra 12hp and 25hp with a propulsive efficiency of 67%.

    View attachment HGPGAssocCanadaTowingInfo.pdf
     
    b7gwap likes this.
  9. Feb 22, 2018 #9

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Excellent guide the Canadians have put together there. All great suggestions. I’ve read that a payout winch is inherently safer than a stationary payin winch like a scooter tow. Does that jive with what you have seen and experienced? Having only ever flown GA SEL, the closest thing I’ve personally experienced has been bungee launches on RC sailplanes. I suppose that’s more akin to a scooter tow than to a payout winch. I do understand why a static line could be dangerous although apparently some people do still use them. Is that what is used for aero tow? Also, the RC aerotow I’ve done requires the attach point to pass through the CG of both Tow and Glider. I imagine if I did decide to build a dedicated tug aircraft, some reinforcement of the attach point would be in order, and finding the appropriate location of that point on any design might prove challenging.

    The ULF-1 is an interesting case for this question since it weighs similar and is clean like a rigid wing HG, but has 3-axis primary controls. If using a scooter winch, a mono wheel undercarriage would be used and maybe a wingtip holder personnel in case the “landing gear legs” hanging out the Flintstone bomb bay doors can’t hold the wings level for launch. If using a payout winch, I suppose a similar setup could be used, but some I’ve seen use a platform mounted to towing vehicle, so that the aircraft launches from the back of the truck at speed. That interface would be a challenge to build for the sailplane since most of these designs seem to be for HG, and also makes me wonder again why exactly payout is safer than stationary winch?

    Thanks everyone for the discussion

    Austin
     
  10. Feb 22, 2018 #10

    choppergirl

    choppergirl

    choppergirl

    Well-Known Member

    Joined:
    Jan 31, 2015
    Messages:
    1,389
    Likes Received:
    485
    Location:
    AIR-WAR.ORG ★★☠★★


    My friend gave me an old 503 and 3 bladed prop to put on the Poorboy, so we'll find out soon enough if it can tow gliders or not; that's my plan anyway. Way back in the day they did it lots (if Youtube videos of same said thing is to be believed as proof) so I'm guessing it works of really lightweight primary gliders and hang gliders. If it's not working, what's the worst, you start to stall out, so you yank the release lever and tweak some more, give up, or accept it won't work. I've decided I want a glider park anyway, it seems a lot more interesting and peaceful than just aspiring to just an airplane. Build an interesting back yard airport and promote events, and the airplanes will come.
     
    Last edited by a moderator: Mar 20, 2019 at 9:21 PM
    b7gwap likes this.
  11. Feb 23, 2018 #11

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    5,079
    Likes Received:
    1,241
    Location:
    North Carolina
    It seems that a low stall speed and a powerful engine are needed. Dorothy with that 503?
     
    b7gwap likes this.
  12. Feb 24, 2018 #12

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Choppergirl: excellent video, thanks for posting it. I am unfamiliar with that sailplane design. It looks very lightly loaded, maybe even light enough to qualify for part 103 unpowered weight of 155 lbs. I kept looking for ailerons, all I saw were those huge flaps. Flaperons? Or is this a 2-axis design with flaps? I’ve never heard of such a design. Very cool.

    Also, I suppose a trike could make a great tug with the right engine.

    Austin
     
  13. Feb 24, 2018 #13

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Looking at the Moyes Dragonfly, I agree it would likely be impossible to be a 103 aircraft. Very neat airplane though. Where is the bridle attached, does anyone know?
     
  14. Feb 27, 2018 #14

    Aesquire

    Aesquire

    Aesquire

    Well-Known Member

    Joined:
    Jul 29, 2014
    Messages:
    2,196
    Likes Received:
    855
    Location:
    Rochester, NY, USA
    the Bailt-Moyes Dragonfly uses a dedicated bridle attached to the tail boom tube and an extension of the rudder post/vertical stab.

    http://www.liteflite.com.au/

    you need 2 basic things for safe aero tows. excess power for short take off and climb. Low takeoff & stall speed with good control at low airspeed.

    the Dragonfly has cartoonishly large control surfaces, and typically uses a Rotax 582 or 912. A great, but slow, flying machine. Real hoot to fly.

    The Ptug will tow with a 503. It may be one of the few craft to stay under weight for legal pt 103, with a 503. Note that red line speed is determined by flutter at a safe and conservative speed. ( 50-55 IIRC ) the 2 axis control on the Ptug variant of the Pterodactyl Ascender is powerful and effective at low speed.

    Currently a Ptug is on top of my build list. Then I have to get tow rated.

    Winches.... Stationary winches bigger than the Scooter tow versions are overkill for hang gliders, expensive, and limited. Truck tow with payout winch works exceptionally well, and is safer than any other land tow method I know. ( except bungee hill launch ) MUCH safer than simple boat or car tow because the payout system limits the loading.

    It is Vital that you take training to tow, by any method. Hang gliders can "lock out" and turn away from the tow line. if not PROMPTLY released at the glider this is Deadly.

    There is a generation of hard won lessons and technology involved in towing hang gliders, paid for in blood. I am deadly serious. Cliff launch over jagged rocks is SAFER than towing.

    Feel free to reinvent the wheel. There is a REASON the use of weak links, certain types of releases, and the way the PILOT is the part being pulled upon, are standard. Using the system developed is imperfect, can kill you, but solves most of the physics problems that Have killed people.

    http://www.hanggliding.org/wiki/Launch_Methods

    That said, if you can design a better tow plane, Do So. With my blessings and enthusiastic support. You can't ignore the physics.

    Slow take off & climb speed.
    tow line attachment that minimizes the towed aircraft pulling you into a stall or uncontrollable dive.
    tow pilot release of towline, handy & able to operate at overload without flailing parts that can damage the aircraft or kill the pilot.

    EVERYTHING ELSE you can make different, new, innovative, or cheaper.
     
  15. Feb 27, 2018 #15

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Aesquire

    Thanks once again for what seems like a lot of experience in the hg arena. I assure you I take your warnings and recommendations seriously. Thanks also for explaining more about towing methods and pros-cons. Is a payout winch also safer because a scooter tow ultimately leads to the scooter or the turnaround itself? So if you had a separation failure it could drive the glider into the ground?


    As far as the Ptug, wasn’t that a swept delta trike with a forward canard? I thought it was a kit from the 1980s, is it something a builder can still find plans for today?
     
  16. Feb 27, 2018 #16

    Aesquire

    Aesquire

    Aesquire

    Well-Known Member

    Joined:
    Jul 29, 2014
    Messages:
    2,196
    Likes Received:
    855
    Location:
    Rochester, NY, USA
    https://en.wikipedia.org/wiki/Pterodactyl_Ascender

    not a delta. A "ladder frame" swept wing. Tubular leading edge & rear spar. Cable braced, Dacron Sailcloth fabric and battens to hold the airfoil shape from leading edge to fabric trailing edge.
    I hope kits are still available, I have to call the maker. Mr. Dave Froble was a dealer and started making parts to keep his customer's planes flying. It's a small operation with no website.

    A Scooter tow uses a modified highway capable scooter, not the driveway/yard only versions you see at Pep Boys etc. The rear wheel is changed to a drum, and the existing frame, controls, etc. are left alone for ease of use. I've seen them mounted on a small light trailer or rigged to hookup to a tow hitch.

    In any event, like regular winch towing, you start with the glider at one end of a field and the winch at the other. An observer/safety man signals the winch operator when ready to fly, and confirms the pilot's signal to apply power. The line goes taut, the pilot takes several steps or rolls on a dolly, ( that stays on the ground, lightweight tubing & wheels ) and takes off. Steering to aim the nose of the glider at the tow line source, the glider climbs as it crosses the field. When the glider stops climbing, and before the winch pulls everything back down, the pilot releases the line, and goes looking for lift, or glides back to the beginning to fly again.

    Truck & boat towing the olde way uses a line attached to a vehicle, and the pilot/glider, and the whole lengthy assembly moves out, with the glider climbing to it's best altitude. ( depending on speed, relative wind, wing loading, and gremlin morale ) Then release, and fly away. This is more dangerous than the winch launch, because the length of line is fixed and the pull of the car/boat/snowmobile/etc. harder to control.

    Truck/boat payout winch systems use a drum full of line and a brake system controlled by a tension gizmo, to not pull harder than a set amount. ( adjustable, so you can tow different weight & drag craft ) The most popular method has a frame to rest the glider w/pilot at the back of the vehicle, but some systems just pull you up from the ground behind the vehicle. In either case the vehicle moves out, the glider takes off as soon as flying speed is reached, and climbs, pulling the line off the winch drum, as the vehicle cruises along.



    Length of field, length of line, and glider performance dictate how high you can climb in a complicated equation. The payout winch can also compensate for winds aloft, and is IMHO the safest, best land/sea tow system.

    Additional but really really important details like the bridal system that attaches you and the glider to the line vary a bit from system to system, but not much, and are best leaned from current reference books and proper training.

    All these systems should use a weak link, usually a piece of rated cord knotted in an arcane fashion by a High Priest Of The Cult. Or someone who read the instructions. The weak link is supposed to break if line tension gets too high. And usually does.
     
    Last edited by a moderator: Mar 20, 2019 at 9:21 PM
    choppergirl and oriol like this.
  17. Mar 2, 2018 #17

    b7gwap

    b7gwap

    b7gwap

    Well-Known Member

    Joined:
    Sep 1, 2014
    Messages:
    221
    Likes Received:
    26
    Location:
    UT
    Aesquire,

    Do you have any designs of payout winch to which you are partial? I've seen a lot on the web of people building their own.
     
  18. Mar 2, 2018 #18

    jedi

    jedi

    jedi

    Well-Known Member

    Joined:
    Aug 8, 2009
    Messages:
    1,662
    Likes Received:
    372
    Location:
    Sahuarita Arizona, Renton Washington, USA
    Payout winch for sale or rent. PM me if interested.
     
  19. Mar 2, 2018 #19

    Aesquire

    Aesquire

    Aesquire

    Well-Known Member

    Joined:
    Jul 29, 2014
    Messages:
    2,196
    Likes Received:
    855
    Location:
    Rochester, NY, USA
    I suspect many of the home built payout winches began with the phrase, "I got a deal on X yards of towline...."

    No, I don't have a preference among the commercial brands. Remember the cliche, "I don't know art but I know what I like"? Most payout winches use a car disk brake for tension control. If the welds look like bad toothpaste and the mechanism looks Rube Goldberg....... I just look and consider how the winding motor works, and think if I want the assembly as a whole pulling me up a cliff. So far I've never run screaming away, but that's just me.

    AS to the original question, I think it possible to built a pt103 compliant glider tug, but it would have to be built extremely weight conscience to get the most HP engine to fit. No extra fru-fru like a cabin or wet bar. By moving up to the next weight class, and focusing on the slowest stall speeds, and control at those speeds, it's a lot easier.

    I favor the Bailey-Moyes Dragonfly over the trikes mostly because most of my limited experience is with the Dragonfly, and it's design is superior for keeping the tow line out of the propeller, and the comically oversize tail surfaces reduce the problem of the towed aircraft pointing the tug's nose up or down. ( if/when they get out of position.)
     
  20. Mar 3, 2018 #20

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    5,079
    Likes Received:
    1,241
    Location:
    North Carolina
    I've pondered adapting my 103 to tugging:
    Switch from 4 stroke to 2 stroke.
    More lift to lower stall. I'm not sure slots would be that useful on my current airfoils, so a new wing might be needed. So, change a mere 75% of the aircraft and it'll be good to tow!
     

Share This Page

arrow_white