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Please Help. Need Senior Telemaster CG

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Please Help. Need Senior Telemaster CG

Old 12-26-2004, 02:04 AM
  #1  
dirtypool
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Default Please Help. Need Senior Telemaster CG

I bought a used Senior Tele and there is no instruction book. I dont know where the cg should be?

Does anyone out there have one? It is the 8' version (or so). Possibly the ARF version. The covering is adhesive backed yellow in color with HobbyLobby decals and Senior telemaster decals.

Thank you,

Rob
Old 12-26-2004, 06:31 AM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Hi,

You have the ARF version. Due to the lifting tail, the CG is between 5.5 inches and 6 inches from the leading edge. I would start at 5.5 inches and move the cg back after I fly it a few times. With a lifting tail, the CG also depends on the total load the airplane is lifting.

Elson
Old 12-26-2004, 10:17 AM
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Rodney
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Default RE: Please Help. Need Senior Telemaster CG

rcbugman, even on the Telemaster, that lifting tail lifts DOWN. The airfoiled tail does have one advantage though as it takes less downthrust on the engine to compensate for increased speeds at high throttle, the DOWN lift is decreased as speed increases which minimized the climbing characteristic so often obtained with the ClarkY wing airfoil. That is somewhat immaterial though to the original question "Where is the CG?". A good starting point is "right on the main spar" and then change it as required to get the flight characteristics you want. One of the nicer things about the Telemaster is that there is a wide range of where the CG can be and still have controllable flight.
Old 12-26-2004, 11:11 AM
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bentgear
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Default RE: Please Help. Need Senior Telemaster CG

Rob, sounds like you may have the ARF version. If the fuse behind the wing section to the tail is light ply with lightning holes instead of sticks it is the ARF, and I think is the better of the the two planes. Mine is at about 5 3/4".

Elson, good to see you back, have not seen any of your posts lately. Hope the "bugs" didn't get you down.

Rodney, on the main spar issue, would you use the front main spar or the rear for CG.? The front is at 4 1/8 and the rear at 7 3/8 on the ARF? Both well out of the suggested CG range.

Ed M.
Old 12-26-2004, 02:39 PM
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dirtypool
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Default RE: Please Help. Need Senior Telemaster CG

Thanks for the quick replies.

I'll mark the wing with the fore and aft ranges now, so I won't run into this again.

Rob
Old 12-26-2004, 10:04 PM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Rodney,

From your post, it appears that you don't have much experience with the Sr. Telemaster. This airplane has been the center of my aerial research project for nearly 10 years. My current highly modified version has a takeoff wt of 36 lbs but uses the same lifting tail and wing incidence as the original ARF I started with 10 years ago when the planes were weighing a mere 15-18 lbs.

The CG on the Sr. telemaster is between 39 and 40% of chord (according to the book). The book also states that the CG is between 5.5" and 6" behind the leading edge.

I prefer a 6" cg but the pilots who fly for my research efforts prefer a 5.5" cg and the improved tracking. It makes for less tiring flight during the long 35 min sampling flights.

If you flew a Sr. telemaster for any length of time, you would first notice that the lifting tail lifts off the ground early in the takeoff run and settles very late after touchdown. If you have incorrect incidence in the tail or the cg is too far back or the plane is too heavy, the tail does not lift during acceleration before breaking ground. Once airborne and the fuse comes level, then the lifting tail provides down force to lift the nose.

You are at a disadvantage when discussing this air frame. I have several hundred hours on this air frame using it for many air sampling tasks.

Cheers Elson
Old 12-27-2004, 01:45 PM
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Rodney
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Default RE: Please Help. Need Senior Telemaster CG

Dirtybird, just to be sure I just dug out the plans for the Sr. Telemaster. The recommended CG is exactly under the main spar, exactly 5 inches aft of the leading edge. There is only one main spar on the original Telemaster. I'm sorry Bugman does not understand the physics of flight. The main lift vector on the wing is aft of the CG, therefore the lifting tail must lift DOWN for stability. The reason that the airfoil used on the SR. Telemaster works is because the tail is set at a negative incidence relative to the wing so very inefficiently lifts DOWN. Sure the tail lift early on takeoff, just as any other taildragger does, however that does not mean that the tail is lifting UP during flight, quite the converse is true. The advantage of that setup lets you increase power to increase speed without having to make radical elevator trim changes as forward speed increases As said above, this is irelative to your question on CG, just an interesting fact that you can verify with your local aeronautical engineer.
Old 12-27-2004, 04:37 PM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Tsk, Tsk Rodney,

We are on our 10th variant of the Sr. Telemaster. The current fleet is 12 identical planes along with 6 split tail mdels of the Telemaster. If you look at the picture beside my name, that is a Sr. Telemaster ARF powered by a 3W-24 towing an 18" insect net. I think we understand the plane.

If you read carefully my post, you will see that I don't disagree with you on the downforce, just when the downforce takes place.

Have you flown a Sr. telemaster? The tail lifts much quicker than any other tail dragger.

The ARF also has 2 spars where the kit as one spar. The 2 spar wing is far superior in strength.

While the plane will fly at 5" cg, it will require up elevator to trim. It is better to fly a nose heavy plane than a tail heavy plane.

If you remove the dihedral from the main wing, the plane flies much better. If the plane is marginally powered, the adverse yaw built into the plane requires coordinated turns. Differential aileron really helps the adverse yaw problem with the airframe.

Cheers Elson
Old 12-27-2004, 05:01 PM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Rodney,

Your challenges are welcome and have brushed away a few cobwebs since we have experimented with this airframe for more than 10 years.

If you build a Sr. Telemaster with the same incidence as the wing as we did a few years ago, you would find that the plane flies identical to the Sr. telemaster ARF or the kit built plan (we have had both types). In this case, the lifting tail is not applying down force.

The reason for the neg incidence in the Sr. Telemaster horz stab is for a gentle dive recovery. Without the neg incidence in the horizonal stab, the plane is much more pitch unstable and has a very nasty dive which becomes worse as speed increases and the dive recovery is not very pleasant. Add a 1.5 degree neg incidence to the horizonal stab (the difference between the wing and stab incidence on the plans) and the plane has pitch stability and recovers from the dive by itself since the neg incidence stab lifts the nose.

Cheers Elson
Old 12-27-2004, 08:44 PM
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dirtypool
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Default RE: Please Help. Need Senior Telemaster CG

Thank youfor all of the input.

I did not intend to start an argument (heated discussion) but it is comforting to see all of the knowledgeable forum members.

Thanks again.

Rob
Old 12-27-2004, 09:03 PM
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bentgear
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Default RE: Please Help. Need Senior Telemaster CG

Heck Rob, that ain't no argument, thats just two guys having fun. You'll know when the arguing starts.


You never did confirm if you had the ARF or not.

Ed M.
Old 12-27-2004, 09:18 PM
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dirtypool
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Default RE: Please Help. Need Senior Telemaster CG

Yeah, I have seen arguments over in the servo forums. Pages and pages of electrical engineer regurgitation with historical facts of servo history.

I do have the ARF as it has the yellow shelf paper with Hobby Lobby's logo and lightened ply fuse top. 2-piece wing has wood joiner.

Rob
Old 12-27-2004, 10:18 PM
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bentgear
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Default RE: Please Help. Need Senior Telemaster CG

Rob, if you need a .pdf of the arf manual send me an email address via PM.

If you go to tighten the covering use a heat gun. Big PITA. As you heat the PVC it will fist get soft and sort of bag out of shape and then as you work it it pops up tight. Also smells just like you were burning a PVC pipe so you will need vetilation.

Using a OS 91 FX on mine. Well overpowered for anything I need. It does help when I am taking pictures and have to take off in a short area. Landings can be a problem tho.

A larger rudder would help. The ailerons have way too much leverage on the stock rudder to get a good high angle slip going.

Ed M.
Old 12-28-2004, 10:30 AM
  #14  
Rodney
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Default RE: Please Help. Need Senior Telemaster CG

I think that I and Bugman agree on more than we dissagree on; one fact seems to be that we think all versions of the Telemaster have been quite pleasant flyers. I've had two of the originals, two of the 40 sized and am currently flying the Mini Telemaster with an outboard electric motor (redeisigned wing however with no dihedral and ailerons). All have been exceptionally good flyers and have given lots of enjoyment. I think we both agree also on the fact that they fly better with no dihedral, at least if you want some degree of stuntability. I respect Mr. Bugmans comments and appreciate them.
Old 01-02-2005, 06:29 PM
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dirtypool
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Default RE: Please Help. Need Senior Telemaster CG

Ok, got my first flights in on it today.

Super Tigre 61 still breaking in, but got it to run pretty consistently. It was a bear to keep running during the first 2 tanks on the break-in. Part of the problem was the glow plug that came with the motor.

Rudder is pretty useless on that plane especially at low speed. Ailerons need more throw as they are not very effective, especially at low speed.

On about my fourth flight I took off and got up to altitude and started making some turns when she banked over and wouldnt stop turning. Aileron servo went out - it was an FMA 350, about 4 years old, never used before. So I had to keep full right aileron to counter the left aileron being stuck in the "up" angle. So, what I had was full right aileron, while trying to bring it in on rudder with both ailerons turned into full throw spoilerons. A bit tricky considering I have only flown once in the last few years. That seemed to rattle the cobwebs out of the noggin. Brought it down to a perfect landing.

So, I had a couple of good flights, a deadstick and a servo failure all on the same day.

Now, I am going to pull out the FMA servos and put in some Hitecs or maybe a couple of Futabas I have laying around. Maybe I will also put a larger rudder on as suggested.

This thing is a huge sluggish beast.

Thanks for all your help in getting me set up on this plane.

Rob
Old 01-02-2005, 07:18 PM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Hi,

Glad you got the plane down with no problem. You need at least a 90 glow 2 stroke or a OS 108 is great.

If possible, make some straight spars and remove the dihedral from the wing. Also, set up your ailerons with mechanial differential.

Then the plane will fly a lot better.

Elson
Old 01-02-2005, 08:18 PM
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Default RE: Please Help. Need Senior Telemaster CG

Thanks.

The spars are glued into one of the wing halves. I'll have to investigate the amount of work on that one.

When you say aileron differential, should it be giving more up or more down? I know how to do it mechanically and my radio will also do it. I have never done it before though and dont know if you give it more up or more down.

Rob
Old 01-03-2005, 06:11 AM
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rc bugman
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Default RE: Please Help. Need Senior Telemaster CG

Rob,

On high wing planes, you want to use more up aileron than down on the differental. This reduces the adverse yaw tendency of the telemaster. I usually position the arms at 2 oclock and 10 oclock rather than the center which is 3 oclock and 9 oclock.

Elson
Old 04-03-2005, 12:09 AM
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Default RE: Please Help. Need Senior Telemaster CG

This might help?
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Old 04-03-2005, 12:15 AM
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Default RE: Please Help. Need Senior Telemaster CG

Guess the CG on this telemaster [:-]
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Old 05-15-2005, 10:51 PM
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Default RE: Please Help. Need Senior Telemaster CG

I've got a Senior Telemaster ARF that I haven't built yet. I plan on using a OS Max H-80 for power. Maybe you guys can give me a few pointers on how to attach the wing without using rubber bands and how much I should enlarge the rudder. I removed the yellow shelf paper covering, it was too far gone. I've read that the kit version wing will warp if you use a Super Coverite type of fabric covering material. Have any of you used fabric on the ARF version?

Thanks
Old 05-15-2007, 03:03 AM
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Default RE: Please Help. Need Senior Telemaster CG

i have the telemaster kit. 94 inch wing. tower hobbie .61 engine. the plane weight is around 12 lb. i have only flown it about 10 flights but find it is unstable in the air. i have trouble getting it to fly level at all times. i have installed a jvc camcorder shooting out the bottom at about a 40 degree angle. i need to fly slow in order for the picture to be clear and some times it will not do that. maybe what i need is more flight time with it. any suggestions will help. thanks
raptoro1
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Old 05-17-2007, 10:18 PM
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dirtypool
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Default RE: Please Help. Need Senior Telemaster CG

That motor is a bit small if you are hauling a camcorder (even a small one). Make sure that the balance point is correct with and without the camcorder.

Mine really got pushed around in the wind. Great calm day trainer, but the rudder and ailerons seemed inadequate for my taste.

Being pushed around by the wind is one thing, but unstable leads me to believe it is not balanced properly.

Also, for a camcorder electric power may be a better choice. Every gas or glow plane I used with a camera had poor video quality. Or, you need to have a good isolation mount.

Good luck.

Rob

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