Servo Torque

[Doug Ashby]

Ok, so how much tork is enough to turn an 1/8th scale?

I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

 

[SayMikey]

Ok, so how much tork is enough to turn an 1/8th scale? I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

I run a hitec 645mg think about it thou you send all that time building and now you want to skimp on radio gear.Id use Futuba minis and a airtronics 8611 if i do it again.

 

[FloridaScaleBoater]

For rudder I use Futaba 3305, and some of my boats are heavy

Futaba mini's or Hitec HS85's have done me right also

Rick

 

[tampa1330]

Ok, so how much tork is enough to turn an 1/8th scale? I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

On one of my recent projects (sport 40) I upgraded to all standard sized High torque digital servos (90oz) with metal gears and man the difference is night and day. Digital servos are so smooth and responsive it's amazing. No chattering, even when under a load. The main thing I look for in a throttle/3rd channel servo is speed and as long as you have a standard/mini sized servo but not a micro servo you should be okay on torque. As far as steering, I would look for something in the 150-200oz ballpark.

Travis

 

[tampa1330]

Ok, so how much tork is enough to turn an 1/8th scale? I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

On one of my recent projects (sport 40) I upgraded to all standard sized High torque digital servos (90oz) with metal gears and man the difference is night and day. Digital servos are so smooth and responsive it's amazing. No chattering, even when under a load. The main thing I look for in a throttle/3rd channel servo is speed and as long as you have a standard/mini sized servo but not a micro servo you should be okay on torque. As far as steering, I would look for something in the 150-200oz ballpark.

Travis

Also one thing I like to keep in mind is that the harder the servos have to work the faster the battery dies. I use li-po for Rx batt and I've noticed that my setups that are straining to function kill the batteries much faster and the ones that don't strain at all the Rx batt last strong through out a full day.

Travis

 

[FloridaScaleBoater]

delete

 

[Mike Cathey]

Ok, so how much tork is enough to turn an 1/8th scale? I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

Hi Doug,

The Futaba 9350 is a great rudder servo and it is a $100 unfortunatly. They are a digital, coreless, dual ball bearing, metal gear water resistent unit that also has metal heat sink plates in it and heavy gauge wiring. It has 111 oz. of torque at 4.8 volts and 130 oz. of torque at 6.0 volts. It has all the speed you need. If you have a gonzo sized turn fin you may have to even slow it down with the TX set up to keep the boat from coming around too fast and making 90 degree turns. It also comes in s standard size case. I've never had one blow up on me yet.

I agree with Mike that the radio gear is not the place to scrimp. I send all of my stuff (tx, Rx and servos) back to Hobby Services every year. It usually costs me a $60-$100 but the piece of mind is worth it. I also replace my RX switch in every boat every season with a new one. You can't see if there is any corrosion inside the switch housing or contacts and if it goes bad on the water, your failsafes won't work and there goes your baby into the beach at 60mph.

Are you going to make it out this year for a race? I know you've been working on some new stuff.

Let me know if I can help.

 

[Bill Brandt]

I use a Futaba S148 for my rudder servo. Only problem is, every time I go to turn I hit the beach. Some people go through a glow plug every run, I go through a boat... :lol: :lol: :lol:

Seriously JR 8411, 8611 or 8711 are in my opinion the best. As you see there is much advice. The one important thing is don't rely on cheap radio gear in a scale hydro.

 

[Mike Cathey]

I use a Futaba S148 for my rudder servo. Only problem is, every time I go to turn I hit the beach. Some people go through a glow plug every run, I go through a boat... :lol: :lol: :lol:
Seriously JR 8411, 8611 or 8711 are in my opinion the best. As you see there is much advice. The one important thing is don't rely on cheap radio gear in a scale hydro.

Hi Bill,

My first boat was Ron Erickson's old Speedy and it had a pair of 148's working in tandem. I guess that's what they had to do in the "old days" to get enough servo power. Even then it was woefully inadequet considering the boat weighed 22 pounds! The U 3 I'm working on now is just under 13 lbs with all the gear in it, less the paint.

 

[Don Ferrette]

Tried & true Futaba 9405. 100oz @ 6 volts, $64.99 @ Tower. B)

http://www3.towerhobbies.com/cgi-bin/wti00...LXBXA8&P=SM

 

[Mike McKnight]

I've got this one in every scale boat I have without a single failure. Hi-Tec HS-5985MG High Torque Metal Gear Digital.....Torque: 144.42oz (10.4kg) @ 4.8V 172oz (12.4kg) @ 6.0V

$84.99. I have 4 winged boats and a shovelnose that range from 14-17lbs. I think I even have them or one similar in my riggers...

 

[Doug Ashby]

Ok, so how much tork is enough to turn an 1/8th scale? I don't want to spend $100.00 on a servo if I don't have to.

I guess the same question would apply to the speed of the servo as well.

Also, how small (low tork) can you go for the throttle and 3rd channel servos?

Hi Doug,

The Futaba 9350 is a great rudder servo and it is a $100 unfortunatly. They are a digital, coreless, dual ball bearing, metal gear water resistent unit that also has metal heat sink plates in it and heavy gauge wiring. It has 111 oz. of torque at 4.8 volts and 130 oz. of torque at 6.0 volts. It has all the speed you need. If you have a gonzo sized turn fin you may have to even slow it down with the TX set up to keep the boat from coming around too fast and making 90 degree turns. It also comes in s standard size case. I've never had one blow up on me yet.

I agree with Mike that the radio gear is not the place to scrimp. I send all of my stuff (tx, Rx and servos) back to Hobby Services every year. It usually costs me a $60-$100 but the piece of mind is worth it. I also replace my RX switch in every boat every season with a new one. You can't see if there is any corrosion inside the switch housing or contacts and if it goes bad on the water, your failsafes won't work and there goes your baby into the beach at 60mph.

Are you going to make it out this year for a race? I know you've been working on some new stuff.

Let me know if I can help.

Hello Mike. I'll be at Chehalis. I was out at Ellensburg last weekend, but I hit a fish at the start of the first heat. I can fix it before the next race...

 

[larcor69]

there's NO question about radio gear, I see so many I call Good Ol' guy's with 1000'S in there boat's running radio gear that date's back to the 80's.??? wow, with all the good stuff out now, why even think about running such dated radio system's in your new 1/8th boat you spent building for a year with love and devotion, to controll it with old dated radio eqpt.??, servo torq. for a rudder on a 1/8th scale boat should be at least, 200+ oz.in's !!! and they make 400+ in a standard size now aday's too!!!, JR 9100T 430 ozin. at 6v!!!

 

[Don Ferrette]

servo torq. for a rudder on a 1/8th scale boat should be at least, 200+ oz.in's !!!

The one thing some of you are overlooking is the mah rating of your battery pack. While there are some digital servos with very high torque ratings they are absolutely brutal at sucking the life out of even large mah packs. 100oz of torque in a high quality metal gear servo is plenty for a properly set up 1/8 scale. B)

 

[Mike McKnight]

Agreed. In days gone by I used to use 200+ oz servos. But if your boat is set up correctly you shouldn't need to put that much stress on the runner and linkage. If the rudder and turn fin are working anywhere near optimum efficiency you shouldn't need 200oz.

 

[glenng]

servo torq. for a rudder on a 1/8th scale boat should be at least, 200+ oz.in's !!!

The one thing some of you are overlooking is the mah rating of your battery pack. While there are some digital servos with very high torque ratings they are absolutely brutal at sucking the life out of even large mah packs. 100oz of torque in a high quality metal gear servo is plenty for a properly set up 1/8 scale. B)

O.K. Don, Now you got me worried. I'm just finishing a new boat and used a airtronics 200 oz servo with a 1100 or 1200 mah 6v nicad pack. Should I swap out the servo or give it a try? It's not a heavy boat and has pleanty of rudder and skid fin in the water. Thanks', Glenn

 

[AndyBrown]

We use 100 to 130 oz. Airtronics or Futaba in our twins and never have need for any more power. Beware of low cost servos that claim to have torque in that same range. In our experiance they do not and won't hold a big boat in a straight line.

 

[Don Ferrette]

servo torq. for a rudder on a 1/8th scale boat should be at least, 200+ oz.in's !!!

The one thing some of you are overlooking is the mah rating of your battery pack. While there are some digital servos with very high torque ratings they are absolutely brutal at sucking the life out of even large mah packs. 100oz of torque in a high quality metal gear servo is plenty for a properly set up 1/8 scale. B)

O.K. Don, Now you got me worried. I'm just finishing a new boat and used a airtronics 200 oz servo with a 1100 or 1200 mah 6v nicad pack. Should I swap out the servo or give it a try? It's not a heavy boat and has pleanty of rudder and skid fin in the water. Thanks', Glenn

Well all I can tell you is in my 1/8 scales I use the Futaba 9405 with a 6 volt 2150 mah NiMH pack and that gets me through a 3 day event just fine. Personally I think 1100 mah is a not enough for for even a non digital servo like the 9405 unless you charge it after each day and if it is a digital I would be concerned. Another thing is if you use 2.4 radios & you go below the reset threshold of the RX the time to reacquire is much greater than FM or PCM. I would try to get at least 1800mah in there.

 

[glenng]

servo torq. for a rudder on a 1/8th scale boat should be at least, 200+ oz.in's !!!

The one thing some of you are overlooking is the mah rating of your battery pack. While there are some digital servos with very high torque ratings they are absolutely brutal at sucking the life out of even large mah packs. 100oz of torque in a high quality metal gear servo is plenty for a properly set up 1/8 scale. B)

O.K. Don, Now you got me worried. I'm just finishing a new boat and used a airtronics 200 oz servo with a 1100 or 1200 mah 6v nicad pack. Should I swap out the servo or give it a try? It's not a heavy boat and has pleanty of rudder and skid fin in the water. Thanks', Glenn

Well all I can tell you is in my 1/8 scales I use the Futaba 9405 with a 6 volt 2150 mah NiMH pack and that gets me through a 3 day event just fine. Personally I think 1100 mah is a not enough for for even a non digital servo like the 9405 unless you charge it after each day and if it is a digital I would be concerned. Another thing is if you use 2.4 radios & you go below the reset threshold of the RX the time to reacquire is much greater than FM or PCM. I would try to get at least 1800mah in there.

Thanks' for the info Don, I do have 3 1800 mah nicad packs I can use. Also forgot to mention boat has a fail safe that will close the throttle if battery voltage drops too low. And as of today there are no one, two or three day events in Northern Utah. Thanks', Glenn

 

[K.R.Joye]

Unless your boats a pig all you'll ever need is a HS645MG. When Scales are in `float mode' at 60plus doesn't take much to turn them.