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Help with servos - 3/24/2008 11:47:50 AM   
goirish



Posts: 1388
Joined: 12/7/2005
From: Litchfield, MI, USA
Status: offline 		I put this post on the beginners forum but no responses. Maybe someone here can help.

I am building a ACE SeaMaster 120 and putting a Magnum 180 4s on it. I would like to do Pull-Pull on the rudder and elevator. Probably use 4 servos for the ailerons. Anyone have any thoughts on putting flaps on this. What kind and size servos would you all recommend.

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RE: Help with servos - 3/24/2008 4:52:00 PM   
jrf


 

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quote:

I put this post on the beginners forum but no responses. Maybe someone here can help.


Are you a beginner? Do you have previous experience with large scale RC models, large glow engines and RC seaplane flying?

You sound like you may be a little over your head on this one.

Jim

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RE: Help with servos - 3/24/2008 5:25:37 PM   
goirish



Posts: 1388
Joined: 12/7/2005
From: Litchfield, MI, USA
Status: offline 		I fly a sea dancer with a magnum 91 4 stroke. I am not a 3D pilot. I just putter around. I also have a dehavilland Beaver on floats 75 ASP. So that is my extent on larger engines. I do a lot of scratch building. Mostly in the 46 to 52 range. Have been using HiTec 322 servos on most of them. I have some Planes that have the pull-pull system. Just not sure the servos that I have been using may be enought. Thanks for the concern. My Dehavilland Beaver has flaps and that is why I was wondering about putting flaps on this one. Does not show it in the plans.

The Dehavilland Beaver is the one shown on the left of this message.

< Message edited by goirish -- 3/24/2008 5:26:35 PM >

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RE: Help with servos - 3/24/2008 5:42:33 PM   
jrf


 

Posts: 2389
Joined: 12/30/2001
From: Burbank, CA, USA
Status: offline 		Ok, first of all I would recommend that you do a search here and on any other RC forum you can find for the SeaMaster 120. With few exceptions, it was considered a very poor flyer. The kit was discontinued after the first production run. If you decide to go ahead with the build, there are some fixes out there that you should definitely use.

If you still want to proceed, you will probably need 70 ounce servos (HS635) on the ailerons. One for each aileron will be sufficient, you do not want to get into buying matchboxes to balance two servos on each aileron. Using a single servo each for the elevator and the rudder, you should consider something in the 100 oz range (HS645).

A high landing speed was not one of the SM 120s problems, but weight was, so I would say that flaps would probably be a bad idea. Still, if you want to install them, use HS 475s.

And finally, treat that 180 four stroke with the upmost respect. A 91 can cut you badly. A 180 can amputate.

Jim

< Message edited by jrf -- 3/24/2008 5:55:55 PM >

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RE: Help with servos - 3/24/2008 5:49:29 PM   
goirish



Posts: 1388
Joined: 12/7/2005
From: Litchfield, MI, USA
Status: offline 		Thanks for the info. The plane is in the Bones now. Just finishing up the Pod. Have not installed any electronics yet. Still thinking about the pull-pull system on the rudder and elevator. I will scrap the flaps. It is heavy because it is all ply-wood. The kit plans show a OS 120. So I would think the Mag. 180 4s would be about the same. Maybe I will fly it off the snow like I do some of the other ones on floats. SeaDancer handles the snow great.

< Message edited by goirish -- 3/24/2008 5:50:12 PM >

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RE: Help with servos - 3/24/2008 6:29:08 PM   
goirish



Posts: 1388
Joined: 12/7/2005
From: Litchfield, MI, USA
Status: offline 		After I set the rudder and elevator on, I don't think I will be doing pull-pull. Just do what the plans call for. That's what I need to do. Quit fooling around trying to do something that probably won't work anyways. If there is a easy way and a hard way I look a long time at the hard way. Would the 180 4 stroke be somewhat the same as a 120 2 stroke? Don't want to under power this puppy.

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RE: Help with servos - 3/24/2008 7:08:21 PM   
jrf


 

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Status: offline 		The 180 should fly it OK. It seems that most of the ones that flew used small gas engines, but that certainly didn't help the weight problem.

The best advice I can give you is to add triple vertical fins similar to some Beavers, but larger, more like a Lockheed Constellation airliner. The only one I ever saw that flew consistently, had that modification.

Jim

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RE: Help with servos - 3/24/2008 7:34:37 PM   
goirish



Posts: 1388
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From: Litchfield, MI, USA
Status: offline 		Thanks Jim

I will try that and let you know if the birdy flys OK

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RE: Help with servos - 3/25/2008 2:20:46 PM   
goirish



Posts: 1388
Joined: 12/7/2005
From: Litchfield, MI, USA
Status: offline 		Jim

Is this kinda what you had in mind. Putting three of these across the stab.
Thanks
Gene

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< Message edited by goirish -- 3/25/2008 2:22:07 PM >

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RE: Help with servos - 3/25/2008 4:11:18 PM   
jrf


 

Posts: 2389
Joined: 12/30/2001
From: Burbank, CA, USA
Status: offline 		Yes, that is it. I would make one that follows the shape of the kit fin for the center. You can put the outer ones above or below the stab, or centered, whichever you think looks better and make them any shape that pleases you, just as long as the area is sufficient. (With three that size, I would think it is.)

Jim

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