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What servos do I need

Old 01-19-2008, 11:16 PM
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cwhipple
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Default What servos do I need

I recently traded my way into a 86" QuiQue Yak and it is time to purchase servos. I am not going to fly 3-d with this plane and will be using a 45cc motor. What servos should I use with this application? Has anyone tried TowerPro servos or HXT12K's? They are high-torque at a low cost but are they reliable? Any help would be appreciated. I would also be interested in purchasing 5 servos if anyone has a good deal on servos that fit this application.
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Old 01-19-2008, 11:55 PM
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XJet
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Default RE: What servos do I need

None of the TowerPro (rebadged as HX servos) I've looked at are really of sufficient quality to be a sensible choice for a 50cc plane.

They have plenty of torque but the gearsets wear really quickly, the pots wear even faster and they have a number of other deficiencies.

The TowerPro MG995 is probably the worst -- just do a search and you'll see all the problems.

The replacement servo (the TowardPro [sic] MG996R) doesn't have quite the same overshoot problems but is very heavy and still suffers from the same gearset and pots.

You've got a nice plane there -- don't penny-pinch on cheap servos of dubious reliability and performance.

If you want to save money, check out the metal-geared SV servos from HobbyCity/United Hobbies -- they're a much better option than the TowerPro/Towardpro/HXT units.
Old 01-20-2008, 01:55 AM
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cwhipple
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Default RE: What servos do I need

What torque would you recommend for this plane? Is 100 oz/in good enough for a 50cc plane flying non - 3d?
Old 01-20-2008, 02:17 AM
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XJet
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Default RE: What servos do I need

Even though you won't be flying 3D, the Yak does have 3D-sized control surfaces so you'll still need a good strong servo so as to avoid flutter.

I'd say you're best advised to go for at least 120oz/in and preferably 140oz/in or better. They must also be metal geared -- nylon or other plastic gears will strip at the first sign of flutter or even as a result of hangar rash.
Old 01-20-2008, 08:53 AM
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Default RE: What servos do I need

QQ recommends 180oz or better,,, and I agree....

I put 5955's in mine so I could use the servos again... If I did it over I would use Futaba s9156's

Plenty of torque and a servo I can use in a bigger plane
Old 01-20-2008, 12:02 PM
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Default RE: What servos do I need

Here's one that ought to do the trick if they've got any left...

http://www.servocity.com/html/hs-5985mg_servo.html

They're digital, MG, coreless, 172 oz with a 0.13 transit time on 6 volts, and they are programmable for $63.00 a piece right now. I've got 'em on my 28% WildHare Extra and 4 of them on the ailerons of my 33% Edge, and they're working great.

Best price I've seen on them.
Old 01-20-2008, 12:15 PM
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cwhipple
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Default RE: What servos do I need

I agree that those would be great servos; however, I am not up to spending 60 bucks a servo at this time. How would HItec HS-645MG's work for this application?

Chris
Old 01-20-2008, 03:09 PM
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XJet
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Default RE: What servos do I need

645s would work fine -- but I'd advise a 5-cell/6V flight pack because they're a little slow on 4.8V.
Old 01-20-2008, 03:21 PM
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cwhipple
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Default RE: What servos do I need

I do run 6 volt battery packs. The 645's are a little more in my price range! Anyone have one of these QQ 86" Yaks? How do they fly?
Old 01-20-2008, 03:24 PM
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Default RE: What servos do I need


ORIGINAL: cwhipple

I agree that those would be great servos; however, I am not up to spending 60 bucks a servo at this time. How would HItec HS-645MG's work for this application?

Chris
Then save up until you are....

Do not take a great plane down with sub standard servos.... You will hate the plane if you scrimp on servos...
Personally I think the 645's are some of the worst centering servos I have ever seen.....
But that is just me....
Old 01-20-2008, 03:32 PM
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cwhipple
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Default RE: What servos do I need

Not a bad idea. Any of you have some good servos sitting around that you would like to move?
Old 01-21-2008, 10:23 AM
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Default RE: What servos do I need

I don't want to appear as being callous or not understanding of your financial situation, but it looks like you're in the process of biting off more than you can chew...

While there are ways to save a few bucks on some of this stuff, it's one thing to not be able to afford MG digital servos, it's quite another if you can't afford even upgrading to suitable MG analog servos. I used the 645 Hitecs in my first gasser because I got the model used and after checking the specs, they seemed to suitable for that model, so I flew it with them. They do have some centering problems as noted and I did have to change an aileron servo out for excessive gear slop on that model, it was smaller with much smaller ailerons than the QQ. IMHO, it is not a suitable servo for this model.

This leads me to surmise that should you actually get this thing put together on the cheap, you'll have something that isn't going to last long and when one of these size birds go down it isn't pretty in most cases. Now if all that happened is you lost your model, then that might be acceptable. But what if you lose it and someone gets in the way as it's going down?

While it is possible to put one of these size models together in the $1700.00 range with all new components, it's far more likely to be in or above the $2000.00 range with a nice model like the QQ and say a DA/3W/ZDZ type engine.

Please re-consider your project until you can put together something that is at least safe to operate?????
Old 01-21-2008, 11:47 AM
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cwhipple
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Default RE: What servos do I need

I have decided to the model on the shelf until I can purchase good servos. I would rather do it right when the $$ is there than do it on the cheap and end up crashing the plane!
Old 01-21-2008, 02:01 PM
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cwhipple
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Default RE: What servos do I need

How do you guys feel about these servos? A little more than I want to spend but I don't want to buy another Yak for $650!!!

http://www.servocity.com/html/hs-5955tg.html

Thanks for all the advice.

Chris
Old 01-21-2008, 03:02 PM
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XJet
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Default RE: What servos do I need

I would wait for the "soon to be released" HS7955TG servos instead -- for two reasons.

The 7955TG has *twice* the resolution of the 5955TG and the 5955TGs will almost certainly under go some heavy discounting when the new model hits the market.

I've got 5955TGs in my 90" 50cc Extra 330L and they work fine -- but I have to admit that the resolution isn't all it could be so I do have a little buyer's remorse now that I hear a better servo will be available for the same money -- but that's the RC game :-)
Old 01-21-2008, 03:08 PM
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cwhipple
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Default RE: What servos do I need

Interested in selling your 5955TG's?
Old 01-21-2008, 03:55 PM
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Default RE: What servos do I need


ORIGINAL: cwhipple

Interested in selling your 5955TG's?
Not yet :-)

The current "street price" is about US$89 by the way -- not the $115 that many sites list them at.
Old 01-21-2008, 07:56 PM
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Default RE: What servos do I need

http://www3.towerhobbies.com/cgi-bin...&I=LXPHD6&P=SM

If you are in their club, you can get 5 for ~430 if bought before the end of the month. Same servo as the 5955tg without programming, which you wont need.
Old 01-21-2008, 08:05 PM
  #19  
cwhipple
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Default RE: What servos do I need

What do you guys think of this for an initial setup keeping in mind I don't 3-d?

Elevators: 2 - S3305 Futaba - 123oz

Rudder: 1 - HS5645MG Hitec - 168oz

Ailerons: 2 - HS645MG Hitec - 133oz
Old 01-21-2008, 08:15 PM
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Default RE: What servos do I need

the 5955's would be excellent...

I'm more of a Futaba guy and love my 9156's but I do have an 85" Yak and it has 5955's all around and I am very happy with the setup.......

great choice
Old 01-22-2008, 12:09 PM
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Default RE: What servos do I need

ORIGINAL: exeter_acres

the 5955's would be excellent...

I'm more of a Futaba guy and love my 9156's but I do have an 85" Yak and it has 5955's all around and I am very happy with the setup.......

great choice
This response is in reference to post #19 as the 5955's all around would be great and allow you to use them in something else/bigger down the road shoud you choose to do so.

The 3305 is not an air servo. Futaba only recommends them for surface applications as they have a wider deadband and more gear slop. I will say that I put some of them on a Funtana 90 a few years ago and they seem to be holding up, but there is gear slop in them.

I think if I were you, I'd use the 5985's or the 5645's on everything but the rudder and go for a 5955 there.

As was pointed out, the street price on the 5955's is $90 a pop from various vendors, outside of that link I gave you earlier the 5985's are about $75 a piece if you look around a bit.

I've got something similar to your Yak with that servo combination and it works great on that size model. As for the difference in the new 7955's with the higher resolution and overload protection, that is strictly a money issue I think as the changes while nice are not something I think you'd feel. The other part is that the 7XXX servos are not due out until March, and the manufacturers tend to be optimistic on release dates so I suspect it may be later in the year before they show up. I think they'll also be in the $120 range when they hit the market as the Hitec support forum guys have indicated the 7XXX's will be "similarly priced" which I'm sure refers to MSRP and the 5955's are going for a chunk under that price right now.

Whatever you choose, please keep in mind that you'll need suitable servo arms and linkages, HD servo extensions and HD switches. Those items can add a chunk of change to the price tag for servos...[]
Old 01-22-2008, 07:34 PM
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Default RE: What servos do I need

Good idea!!! A lot of money can be wasted trying to cut corner's on radio gear!! I have the 5955's they are a great servo, and can be used for a larger application like previously mentioned

3DAP

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