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Old May 06, 2012, 08:17 PM
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United States, CO, Arvada
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Telemaster 40 CG help

I picked up a telemaster 40 that was built in '85, it was never flown after it was expertly built. I have changed to a tail dragger and swapped out the K&B 40 for my Enya 60 4 stroke. I need to know exactly where the CG is, the manual says look on the plans but I can't find any on line. I find one source that says 4 3/8", another says 5 3/4", I'm sorry but that's just too much of a variable. So please help me out guys, what is the correct CG?
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Old May 07, 2012, 05:40 AM
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Joined Mar 2004
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I've GOT that unbuilt Telly-40 kit only meters away from me here at home...

Dear Cherokeenut:

The PIPE Here, early on a Monday morning...it's my VERY LAST week of business college coursework, with one online course completed (retailing principles) and one online course to do the final exam on sometime between Wednesday & Friday (personal finance) later this week...there's ONLY the final exam for that online course to complete (all but one of my classes HAVE been online only!) and then I'll be GRADUATING on June 1st with my associate's degree in business administration.

I've been unemployed for just over 3-1/2 YEARS now, and a new college degree should get things going properly to be working full-time once again, the sooner the better!

Well, since I DO have that unbuilt Telemaster 40 kit, I went over to it, pulled out the rolled-up fuselage plan and carefully measured the CG "target" distance behind the wing's leading edge...

...it's got just about a 4-7/16ths inch (112.7 mm) distance from the leading edge of the wing to the CG "target" marked on the plans.

I'm simply hoping that THAT is what you were looking for...

...hope it helps!

Yours Sincerely,

The PIPE....!!
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Old May 07, 2012, 08:54 AM
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It is thanks! That's strange as a youtube vid of a telemaster Sr. shows the CG right on the main spar, wonder why the 40 is different.
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Old May 07, 2012, 09:07 AM
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A lot of people, me included get lazy and just balance planes on the spar for the first flight. If you keep the CG to about 25-30% of the chord you will pretty much always get a stable plane.
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Old May 07, 2012, 11:37 AM
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Thats what I always do, but reading about the Telemaster and it's unusual elevator I understand that if you balance on the main spar then it will be very nose heavy. I've not run into this before. Every other plane I have balances on the spar, and like I say the telemaster Sr plans appear to be that way too. Pipe do you know why the Sr. and the 40 would be different?
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Old May 07, 2012, 12:28 PM
Fueled by Arabica Beans
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Quote:
Originally Posted by cherokeenut View Post
Thats what I always do, but reading about the Telemaster and it's unusual elevator I understand that if you balance on the main spar then it will be very nose heavy. I've not run into this before. Every other plane I have balances on the spar, and like I say the telemaster Sr plans appear to be that way too. Pipe do you know why the Sr. and the 40 would be different?
True, it does have that lifting tail doesn't it? With a lifting surface in the back rather than just a neutral stabilizer, it will tend to act a little more like a tandem wing where you would just balance between the two surfaces.
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Old May 10, 2012, 12:58 PM
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In my plans for the Tele 40,it states the cg on the spar. I built mine in 1998.

You can't mess up too much on that plane anyway. I fly mine a bit tail heavy,but it doesn't make much difference,just a little floatier on landing.
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Old May 10, 2012, 02:42 PM
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Originally Posted by ant1 View Post
In my plans for the Tele 40,it states the cg on the spar. I built mine in 1998.

You can't mess up too much on that plane anyway. I fly mine a bit tail heavy,but it doesn't make much difference,just a little floatier on landing.
See and that's just what I've been finding. The CG specs for these things seem to be all over the board. Well I balanced it according to Pipe's recomendation so we'll see it it's too tail heavy. I had read as much as 5 3/8" from the spar on one forum, that seems extreme to me. So what you are saying is that if it's tail heavy it should still fly ok enough to land safely? Because the ways it's balanced now if I put the CG on the spar she becomes VERY tail heavy.
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Old May 15, 2012, 09:40 AM
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Quote:
Originally Posted by cherokeenut View Post
I picked up a telemaster 40 that was built in '85, it was never flown after it was expertly built. I have changed to a tail dragger and swapped out the K&B 40 for my Enya 60 4 stroke. I need to know exactly where the CG is, the manual says look on the plans but I can't find any on line. I find one source that says 4 3/8", another says 5 3/4", I'm sorry but that's just too much of a variable. So please help me out guys, what is the correct CG?
Cherokeenut,

I have a Telemaster 70 Arf which is 40 size Tele built in the late 80s early 90s, I to was confused about the different opinions about the proper cg, The pipe also helped me with this as well Jason from Hobby lobby, with the teles lifting tail design I used the 40% formula and it worked just right, I would never put it that far back on my own. Below is a link to the original inquire to Hobby lobby about this, my wing was a little smaller in width than the standard kit size.

http://www.rcgroups.com/forums/showthread.php?t=1514406

Good luck with your tele they are wonderful flying planes.

Brent
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Old May 15, 2012, 12:03 PM
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I did find a set of original plans and the build manual on Ebay, I have the manual so comparing them I am certain I am getting the correct plans. I can't see very well from the Ebay pic but it does look like the CG is on the spar for this plane....AAAAAUUUUGGGG! So we'll see what happend when the original plans get here, I'll post a pic when it arrives.
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Old May 16, 2012, 04:04 PM
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Ok.... I just got my original Hobby Lobby Telemaster 40 plans and the CG is (drumroll...) 4 1/8"! I can't believe there is so much of a difference on this plane, it's like they changed their minds at whim. These plans do not have a date but were designed by Joe Bridi so I know this is the original design.
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Old Feb 25, 2013, 01:43 PM
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i have a telemaster 40 i got from someone with no instructions did that CG work for you?
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Old Feb 25, 2013, 07:57 PM
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Yes it did, I bought a set of Bridi plans off Ebay. The CG on the Bridi Tele was no where near the main spar. I sold the Tele last fall along with the plans so I can't tell you where it ended up.
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