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Old Apr 07, 2011, 08:52 AM
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Dual Elevator Mini Servos in 40-60 sized 3d?

Has anyone used a dual elevator micro servo setup for their 40-60 sized 30 plane? I have a Fliton Extra 330 with a saito 1.00. It has two standard Hitec's setup for the elevator and it's making the plane very tail heavy. Needs 8oz up front to balance

I figure if I can drop 1oz of weight from the tail by switching to micro servos it would significantly reduce the amount of weight needed in the nose.

Any recommendations?

Thanks
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Old Apr 08, 2011, 06:01 AM
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I'll be updating this thread as it happens.

I suppose I should have researched the servo's I installed before I bought them. They are Hitec HS-645MG. At 1.94oz Each, and 107 torque/oz Each, it's no wonder I'm tail heavy.

Im going to find 2 decent metal gear micro servos and install them which should easily allow me to remove the dead weight in the front.
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Old Apr 08, 2011, 07:39 AM
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I would not try this. Although the micros MAY collectively have enough muscle for the job, I don't think the gear trains on them are up to the task. I had a Hitec 5245MG mini servo (not micro) on the rudder of a 40-size 3D ship and it stripped in mid-air. There were no ground strikes prior to the failure.

Just my thoughts. Good luck with whatever you choose.
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Old Apr 08, 2011, 09:42 AM
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I actually do mean Mini, not micro. I'm not used to small electrics so I apologize for the incorrect use of terms.

I was looking at the Hitec HS-85MG which in theory would have plenty of torque and is nice and light. I do get a little worried about stripping gears mid-air. They also have the HS-225MG, but at 1.1oz its not as light as I would like it to be.

I also am looking at the Futaba S3102's Which is a little slower but possibly more robust based on what other people are saying.

I wish more people had experience with mini servos in larger 3d planes. I'd hate to lose the plane because I'm trying something new.

Thanks for the response though
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Old Apr 08, 2011, 10:30 AM
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Quote:
Originally Posted by jmd87 View Post
I actually do mean Mini, not micro. I'm not used to small electrics so I apologize for the incorrect use of terms.

I was looking at the Hitec HS-85MG which in theory would have plenty of torque and is nice and light. I do get a little worried about stripping gears mid-air. They also have the HS-225MG, but at 1.1oz its not as light as I would like it to be.

I also am looking at the Futaba S3102's Which is a little slower but possibly more robust based on what other people are saying.

I wish more people had experience with mini servos in larger 3d planes. I'd hate to lose the plane because I'm trying something new.

Thanks for the response though

Ahhh, that's a little different. The 5645 I mentioned above is the digital equivalent of the 225, so I'm familiar with it. I honestly think that by the time you factor in additional mounting structure, dual linkages, control horns, mounting hardware and don't forget 12 to 15 inches of additional servo extension, your net weight loss will not be enough to offset the nose weight.

I know you hate to hear this, but maybe you could cut into that beautiful fuse and build a new servo bay several inches forward of the existing one. This is a pic of one of my planes that required the same type of modification. It's much simpler on a profile fuse, but you might be able to pull it off on that pretty Extra.

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Old Apr 08, 2011, 10:47 AM
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I actually have the 2 heavy hitec's already installed 100% in the tail of the plane. So it would be a (semi) direct swap of the old servos & what I would hope to be the new lighter servos.

I really really do not want to make new holes for the elevator servos since I would have to patch the existing 2. I'd also like to keep the control linkage short to keep flex & flutter down. At this point I really would love to just swap the current servos for much lighter ones.

Existing servos= 1.94oz x 2= 3.88oz
Above mentioned servos = .77oz x 2 = 1.54oz

Net difference = 2.34oz which doesn't sound like much but if my assumptions are right the tail servos are about 4x further away from CG than the nose weight. So 2.34 x 4-=9.36oz of nose weight i can REMOVE. Considering I have 8oz up front now, that would mean i could remove it all just by swapping servos. This is something I'm really hoping to succeed in.

Sorry to get all nerdy but this has been going on in my head for a few days now
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Old Apr 08, 2011, 11:02 AM
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Quote:
Originally Posted by jmd87 View Post
I actually have the 2 heavy hitec's already installed 100% in the tail of the plane. So it would be a (semi) direct swap of the old servos & what I would hope to be the new lighter servos.

I really really do not want to make new holes for the elevator servos since I would have to patch the existing 2. I'd also like to keep the control linkage short to keep flex & flutter down. At this point I really would love to just swap the current servos for much lighter ones.

Existing servos= 1.94oz x 2= 3.88oz
Above mentioned servos = .77oz x 2 = 1.54oz

Net difference = 2.34oz which doesn't sound like much but if my assumptions are right the tail servos are about 4x further away from CG than the nose weight. So 2.34 x 4-=9.36oz of nose weight i can REMOVE. Considering I have 8oz up front now, that would mean i could remove it all just by swapping servos. This is something I'm really hoping to succeed in.

Sorry to get all nerdy but this has been going on in my head for a few days now
LOL No need to apologize. I tend to do the same thing when faced with a problem. Good luck and let me know how it turns out. I love to hear a good success story.
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Old Apr 08, 2011, 11:05 AM
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Jeeezz, I have a Fliton 330 in box with the idea of using two Hitec 54??s in the tail and a Saito 100. Keep us posted of how you come out!!
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Old Apr 08, 2011, 11:13 AM
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I had the original pushrod system the kit included with a single Futaba S3003. I didn't notice any problems, even with a <50oz servo. I would imagine 2-54's being okay in theory, but again I'm worrying about stripping gears from shock loads.

I just read a review of a 55" 3d hobby shop which had dual Hitec 225's in the elevator. He also had a single 225 on a pull-pull rudder. If a single 225 can survive the rudder of a 55" 3DHS, I would imagine two 85's would be fine in a dual elevator setup.



Quote:
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Jeeezz, I have a Fliton 330 in box with the idea of using two Hitec 54??s in the tail and a Saito 100. Keep us posted of how you come out!!
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Old Apr 08, 2011, 11:36 AM
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After more research, I'm seeing a few planes 55"+ with either a single or dual Hitec 85mg's. I think I'm going to bite the bullet and get a pair of 85's.


Will update (might be a while the way the weather has been lately)
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Old Apr 10, 2011, 03:04 PM
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HS85 with a Saito 100???!!!! I use those on my 40" profiles.

Can you make the elvator a "one piece" unit and use just one servo to drive it?
If so, put a DS8411 (not SA) and problem solved!
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Old Apr 11, 2011, 08:37 AM
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The plane is only a 59" extra... the Saito 100 is a bit larger than recommended

I originally had a single elevator servo, but wanted to put the dual elevator servo's. They are installed, just moving some things around and putting the plane back together. Will hopefully fly it within a week pending decent weather.




Quote:
Originally Posted by gusgon View Post
HS85 with a Saito 100???!!!! I use those on my 40" profiles.

Can you make the elvator a "one piece" unit and use just one servo to drive it?
If so, put a DS8411 (not SA) and problem solved!
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Old Apr 11, 2011, 08:41 AM
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I hope the thumpin' 4-stroke doesn't destroy the gears on the 85MG. I've used them on throttle right up next to the engine, but never on a control surface. Please remember to report back and let us know how it goes.
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Old Apr 11, 2011, 02:39 PM
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I wouldn't use anything less than a Hitec 5245. I use them in a dual setup in my Phoenix Extra with a Saito 100 with good results. The equivalent 225's are terrible in the centering department.
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Old Apr 11, 2011, 03:17 PM
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Originally Posted by StrangeGager View Post
I wouldn't use anything less than a Hitec 5245. I use them in a dual setup in my Phoenix Extra with a Saito 100 with good results. The equivalent 225's are terrible in the centering department.
After reading this, I realized I mentioned the wrong servo earlier in this thread. I too meant a 5245MG, NOT a 5645. Sorry if that caused any confusion.
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