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Jun 19, 2007, 01:18 AM
Where's the lift?
dgliderguy's Avatar
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Build Log

New tug-- Senior Telemaster ARF


I'm putting a Senior Telemaster ARF together for the upcoming aerotow season, and thought I'd share the build, so people can see how easy it is to throw a tug together. I've got a Thunder Tiger 1.20 Pro two-stroke engine for it, and that combination should haul up the 3-meter to 4-meter ships (5 lbs to 15 lbs) with no trouble. The Senior Telly is a nice-sized tug, at 94" span, and it is also affordable, at just over $200 from Hobby Lobby (http://www.hobby-lobby.com/srtele-arf.htm).

Mods include: Removable tail, so I can tote it in a cartop carrier, bolt-down wing retention (the kit calls for rubber bands and dowels-- yeah, sure), aerotow release mechanism, bigger wheels for rough turf operations and prop clearance, tail-mounted servos for rudder and elevator, and a larger rudder for better yaw control.

I'll let the pics tell the story.

Don.
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Jun 19, 2007, 01:29 AM
Where's the lift?
dgliderguy's Avatar
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I know through experience that Telemasters have wobbly tails, so I decided to sheet the aft fuselage sides with 1/64th ply for more torsional stiffness. This also allowed a mount for the tail servo wells. The stock fuselage is made of soft balsa, die-crunched, and needs the added stiffness.

I also added some area to the rudder, for a more effective control surface. I will be mounting a spring-connected steerable tailwheel under the stab, so I needed a deeper rudder beneath the stab, for the rudder horn and tailwheel hook-up.
Jun 19, 2007, 01:35 AM
Where's the lift?
dgliderguy's Avatar
Thread OP
The tow release is a simple croquet-hoop-and-pullwire affair. Cheap and easy, and foolproof. My tow release servo is a 100oz-in draft horse, for good release reliability. The croquet hoop can pull free in a strong yank, which saves the bulkhead for its bulkhead duties. The hoop can easily be replaced in the field, if need be.

So far, we're looking at about five hours worth of work. Engine mounting is coming up next, and then tail servos and tailwheel linkages.
Jun 20, 2007, 03:10 PM
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phil_e's Avatar
Great job so far....keep us posted.
Jun 20, 2007, 05:27 PM
sno
sno
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sno's Avatar
Wondering what the motor $ is? Getting to the point where I may just build a tug and find someone to fly it for me! lol
Jun 21, 2007, 02:21 AM
Where's the lift?
dgliderguy's Avatar
Thread OP
Sno,

I paid $85 for my Thunder Tiger 1.20 Pro, new-in-box, at a swap meet. They go for nearly three times that much retail, so yeah, that was a good score. The 1.20Pro is probably one of the best two-stroke engines of this size ever made. A truly superb piece of machinery. http://www.ehobbies.com/ttr9195.html

You can still get a brand new GMS 1.20 two-stroker for a mere $125 from Tower and elsewhere. The GMS is a great engine, especially at that price (though you will need to get a Bisson pitts muffler for it). http://www2.towerhobbies.com/cgi-bin...?&I=LXDXL8&P=0

The Supertigre G-2300 (1.40ci) is a strong runner, at around $150, but I don't have any experience running these engines. I hear they can be temperamental. http://www2.towerhobbies.com/cgi-bin...?&I=LXFV80&P=0

Another real coal-hauler is the Magnum 1.20AR, going for right around $200. I had the .91AR, and really liked it. http://www.hobbypeople.net/gallery/210821.asp

You could also go with a four-stroke Saito 1.50 or 1.80 or similar, but now you are into the big bucks engines, which would (imo) warrant a nicer airplane; preferrably something scale.
Jun 21, 2007, 02:35 AM
Where's the lift?
dgliderguy's Avatar
Thread OP

more progress...


I mounted my engine tonight, and installed the fuel tank. The tank is long and narrow, so it fits between the engine beams and the stopper extends into the engine compartment. The tank is 470cc, or about 16 fl oz. I'd like a bigger one, but it will do for now.

The tail servos were also installed, and the pushrods fabbed up. I put a spring-steerable tailwheel on it, so I can taxi around like the big boys. The kit has a simple wire tailwheel that inserts into the rudder base. This one is nicer.

Now all I have to do is all the little stuff, like rx/batt/switch, decals and graphics, main gear mounting, etc. Should have 'er done by the weekend, if all goes as planned.
Jun 21, 2007, 12:04 PM
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phil_e's Avatar
What do think of a tug using a Evo 1.00NX ? I already have one that I'm thinking could do the job with a Telemaster.
Jun 21, 2007, 01:05 PM
Where's the lift?
dgliderguy's Avatar
Thread OP
Quote:
Originally Posted by phil_e
What do think of a tug using a Evo 1.00NX ? I already have one that I'm thinking could do the job with a Telemaster.
Not a problem. The Evo 1.00NX would no doubt be a fine choice for sailplanes weighing up to probably 10lbs or so. I hear good things about the nitro-burner Evo engines. How do you like yours?
Jun 21, 2007, 01:34 PM
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phil_e's Avatar
I am very happy with it. We put it in a heavy old .046 trainer. and used it to tow an olyII with it. Due to tow pilot error, all we have left is the engine.
Jun 21, 2007, 07:18 PM
Will fly for food...
flyingvranch's Avatar
Looks real good. Oddly enough I did the same thing you did. Even our wing hold-down system looks the same! I used a ryobi 32cc gasser. Tows nice but is just a little short on power for 4 meter stuff I think. I did an extensive rework like stripping off the low-temp covering and using Utracote and a lot of fuselage reinforcement.. After a tree incident that destroyed the arf wings, I built a set of 9 foot heavy lift wings that are much much stronger and heavier with 5 inch D-tube sections and carbon spar reinforcement, cap strips and a little glass. I made fowler flaps which really helps on landing as the plane weighs 18 pounds. Still flys and floats like a dream. After the crash I saw just how precarious the arf wings were assembled and I'm surprised they didn't fold up in flight. (It might have just been my particular airplane that had ribs that were not glued in at all.) I too enlarged the rudder a lot which really helps when towing. I'll attach some pics. I hope your project is as much fun as mine. I'm sure you'll enjoy towing with it!
Bud
Jun 21, 2007, 07:33 PM
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phil_e's Avatar
Bud,
I noticed that your wheels seem sorta small for this size plane. Are they this size for a reason?
Jun 21, 2007, 07:37 PM
Will fly for food...
flyingvranch's Avatar
Phil,
They are just the stock foam wheels that came with the plane. They are very stiff and have held up pretty well actually.
Jun 22, 2007, 12:53 AM
Where's the lift?
dgliderguy's Avatar
Thread OP
Well, hey, Bud, looks like great minds think alike! Your wing retention does look almost identical to mine. I thought about adding flaps on mine, too, but I'm in a hurry to get it done. I know what you mean about the dubious quality of the internal structure, but I'm not planning on anything other than tame flying, so we'll see how it all holds up over time.

I have some oversized 5" foam wheels that I will be using for improved prop clearance and for all-terrain capability. Sounds like the enlarged rudder was a good idea, too. Man, 18lbs! I'm hoping to come in at around 9-10 lbs or so, with the nitro engine.

So, what do you do with your wing struts when you remove the wings? Do they stay attached, and if so, are they vulnerable to damage at the attach point? I have been mulling over some ideas for easy-release struts, but haven't finalized it yet. Would you say the wing struts are "nice-to-haves" or "gotta-haves"?
Jun 22, 2007, 06:49 AM
Will fly for food...
flyingvranch's Avatar
I used the stock wood struts, but I made the end fittings out of 3/16" thick brass stock. I leave my struts bolted to the wings when in storage. They do stick up and are somewhat of a pain, but they are firmly bolted to the wing so they don't move any. I used a 1/4" hitch pin and clip available at home depot to connect to the fuselage for a no tools installation at the field. I would definitely use the struts with the arf wing. I need bigger wheels too, as my prop is 18 inches and it's real close to the ground now. It's amazing the weight this plane will carry. At 18 lbs the plane will float in dead stick like a trainer. The flaps were worth the effort. I can deploy full flaps and just about hover the plane down the runway at walking speed and still have plenty of lift and control. Best of luck with your project and keep us posted on the results!


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