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Old Nov 06, 2004, 01:26 PM
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United States, MN, Minneapolis
Joined Dec 2002
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engine size needed on telemaster to tow 4-5 meter scale planes

As Ib Jensen has posted, our minneapolis club is just getting into aerotowing.
We have a telemaster kit, nearing completion, but are uncertain of size of engine needed to tow up to 15 pound or less scale ships 4-5 meters.(nimbus, ventus,
We are thinking a G38. (yes?/ no?) what size prop if yes. A G62 would be possible, but will be tricky with CG etc. we have shortened the front of the telemaster in anticipation of heavy tug engine.
any and all advice appreciated.
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Old Nov 06, 2004, 05:24 PM
Don't cut the Yellow Wire
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Ridgewood ,NJ
Joined Jan 2000
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The G62 would be a nice candidate. Our club started with a Telemaster for towing and we have progressed larger stuff. We do have that original Telemaster but with a Brison now.

At present we are using a Brison 95cc motor and a homemade tow plane.

We also have a 80% prebuilt Pegasus tug that we are going to sell if interested.

SCTS (Sussex County Thermal Sniffers)
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Old Nov 07, 2004, 08:26 PM
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Thiells,N.Y
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You will probably be very dissapointed at the end of this project. There will be way to many mods you have to do, to attemt to have a decent towplane. Don't throw good money after bad! We've been there, done that. The plane is a handfull as is ,and after the mods, it is still basically a "Telemaster". with inherent bad characteristics. There are many alternative out there , that will make you a much happier camper. If you are in it for the long haul, look at used 1/4 scale or better yet 1/3rd scale Extra 300, Lazers, spacewalkers, or of course there is the reliable "Pegasus" designed as a work horse. There is a model called the "8 Ball Special" being sold by someone in Syracuse I believe. That is a bit smaller that the Pegasus but very capable of towing larger scale planes at a very reasonable cost. This was our favorite towplane when John Derstine was organizing the Elmira Aerotows. The kit I believe is somewhere around the low to mid $200 mark. You will find it on the web if you do a search.
Good luck,
Regards,
Richard
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Old Nov 08, 2004, 06:45 AM
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New York
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Richard...what about the Schwankee???!!!
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Old Nov 08, 2004, 09:18 AM
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Thiells,N.Y
Joined Jan 2002
427 Posts
Right Steve, that will be our secret..
.By the way the "8 Ball Special is under $200 ,closer to $160 , what a bargain. Here is the Link to "Reids Quality Model Products...http://www.reidsmodels.com/products/products_set.html
Good Luck,
Richard
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Old Nov 08, 2004, 11:18 AM
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Forest Lake, Minnesota
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OH What have I started

All I wanted to do was get my 4m towed

Kevin are you working on the Telemaster?


Ib
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Old Nov 08, 2004, 12:19 PM
Vintage wood is the best!
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Now that is strange......... I posted a reply to this thread with specs on my G-38 Telemaster, along with a picture and it's gone! I did a search of all my posts and it's no where to be found.......where'd it go? ....... lets try again!

My tug is a Senior Telemaster that has been heavily reinforced with 1/32 plywood fuselage sides installed over the existing balsa fuselage, and the wing has a balsa D-tube with cap strips. It rolls on 6" super light wheels with a custom aluminum landing gear. The rudder and tail wheel are driven by a single servo located on the bottom of the airframe at the tail. The elevators are split with a servo on each side of the tail. It is equipped with a 32-ounce tank and two 1800 mAh battery packs with a Jomar EMS battery backer system. All of my scale planes use the battery backer; it is a cheap $50 insurance policy against catastrophic demise of an airframe. Up front is a Zenoah G-38 swinging an APC 18x11 prop that works quite well. Two years ago, it was used to tow up a 28 pound 1/3rd scale ASH-26. You need to remember that two very skilled pilots were at each end of the tow, and the climb angle was shallow to say the least, but it did the job! In the real world, it is more suited to towing 1/4 scale stuff with an all up weight of under 18 pounds.
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Old Nov 08, 2004, 06:43 PM
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USA, NY, Chestnut Ridge
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Kevin- The current trend in aerotow is elevator launches. This is where you climb as fast as you can so that the tow plane can get back to the ground quickly and give the next guy in line a tow. It's not scale, but it can be a lot of fun. I prefer a more sedate pace that looks more realistic.

If all you're looking to do is get a 1/4 scale in the air the G38 will do fine. If you're going to host an aerotow you'll want more.

-Ben
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Old Nov 08, 2004, 07:17 PM
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We are working on a brand new design based upon our existing tail and wing planforms from our 1-26B and E model Schweizers. It is the SA 1-30 Schweizer which was their attempt to enter the light plane market and resulted in a single copy of a quite beautiful little aircraft that they later put into service as a towplane.

This little motor glider will be available soon (we are awaiting research from the Schweizer plant on fuselage construction of the original) in 1:5, 1:4 and 1:3 scales starting with the 1:4. We are planning to use an available SA 270 initially for power.

Nice color scheme too. We have redrawn all of the 3 views from photos of the actual airframe and though Sig and Berkeley and Doc Mathews at Model Aviation had plans or kits out, ours will be the first that is accurate scale.

We hope to have laser cut kits in just a few months.

Tom
tmrcsailplanes.com
"Home of the Schweizers"
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Old Nov 09, 2004, 06:32 PM
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In PA near Elmira NY
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Well lots of great observations here.
I think I have been doing this too long, I have flown most of the tugs mentioned and with as many kinds of motors. We started with Telemasters in 1995.

Relativly scale tows can be achieved with a Telemaster using a two stoke glow 1.08 to an OS BGX1 30cc type glow motor on 4 meter sailplanes. Remember your power to weight ratio, while big gassers can be bolted to a beefed up Telemaster, they weight penalty might hurt you. The lighter glow motors worked well. There are many to choose from these days.
Back in 1995 all we had were telemasters for the most part. We successfully towed 15 pound 6 meter Nimbuses with the 1.08 powered Telemaster, it was pretty ugly, but doable. The set up with a BGX1 type motor was ideal for 10-12 pound sailplanes towed in a scale like manner. If your tow plane weighs 16 pounds, 16 pounds of static thrust is a good if not imperfect benchmark.

What happened next were two issues. We kept getting larger sailplanes to fly, and when we hosted the first Elmira Aerotows, guys kept showing up with huge and heavy sailplanes. Faced with towing larger sailplanes in an event environment, we had to expand our tow plane capabilities. My Friend Robin Lehman was always on the look out for the perfect tug, his search went in many directions from 1/3 scale aerobatic planes to 1/3 scale SIG spacewalkers, to 1/3 scale wilgas. He prefered the scale towplanes from an aesthetic standpoint. What we discovered for event towing and stressfull landing and take off cycles, was that with our average piloting skills, scale tugs took a beating.

Today, at events like the JR Aerotow, skilled tow pilots with scale towplanes do a great job. Times have changed and we all have more experience.

Our first attempt at looking for a non scale tug that was dependable,rugged, relativly inexpensive, and easy to fly was the Dave Reid 8 Ball special. We reinforced the landing gear, put big balloon wheels on it and logged over 2000 tows with this formidable little brute powered by a Brison 3.2 gas motor. I towed a 35 pound German Habicht in a 20 mile per hour wind at the 1997 Elmira event. This was more or less a vertical tow, not going up at a high angle of attack, but kind of hovering to altitude. The 8 Ball would normally be great for sailplanes up to 30 pounds with this kind of power. Its good points were: semisymetrical airfoil, rugged construction, and it was easy to fly.The 8 Ball was the next logical step and proved quite capable.


Another reason for getting away from Telemasters was that although they were easy to fly, they were almost too stable and too susceptable to windy weather. With generous amounts of Dihedral and the flat bottom wing they were terrible in the wind. If your flying on windy days, having a semisemetrical airfoil and small amount of dihedral is a benefit.

That said, we got to the point where we were custom building our Telemasters with plywood fuselages, one piece reienforced wings, shortened tail span (by one bay), heavy firewalls, functional struts, strong landing gear etc, but when all said and done they were still Telemasters. Great flying airplanes, but eventually a very limited towing platform for larger sailplanes. They are not a bad place to start to hone your skills and have fun towing.

Here is a reference article on towing, somewhat dated but good basic information.

http://www.scalesoaring.net/tow.html

JD
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Old Nov 14, 2004, 07:19 AM
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In PA near Elmira NY
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In case there is any interest, I found some old photos of one of th our original "bashed" Telemaster tugs and of the first 8-ball Special built for tow duty.
The Telemaster was built by Jim Blum circa 1996, and as you can see is heavily modified with a flat center wing and bent tips, I think Jim may have made this fuse himself from fiberglass but I am not sure. The motor is an OS BGX 30cc glow motor. We often took out all the dihedral and used barn door ailerons instead of strip ailerons and shortened the tail span by one bay. Notice servos inthe rear for elevator and rudder.

The Eight Ball Was built for Elmira aerotow duty in 1997. The only mods were added sprung gear components and more tail bracing. Power is a Brison 3.2 gas motor. This relativly small tug 84" span, could tow 30 pound sailplanes. The only problem being visibility at extreme altitudes. The 8 Ball normally has a cowl and wheel pants, but were ommited for tow duty.
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Old Nov 14, 2004, 11:52 AM
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Here is a photo from Schweizer of the SA 1-30 towing an SGS 2-22 at Elmyra back in the early days.

Tom
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