What are the risks of using 44 oz-in vs. 54 servos
02-18-2010, 02:13 PM
#1
Thread Starter
What are the risks of using 44 oz-in vs. 54 servos
My KIT calls for 50 oz-in servos. However, I’m on a budget, and I can get four 44 oz-in servos for the price of one 54 oz-in. What are risks to the plane from 44 oz-in servos?
02-18-2010, 02:29 PM
#2
RE: What are the risks of using 44 oz-in vs. 54 servos
Depends on the plane and the type of flying your are doing, you MIGHT be able to get by with a lower torque servo. The biggest issue you are going to face will be that the servo won't be able to handle the load put on it. The results of that could range from not being able to move the control surface adequately while flying to the servo actually being damaged or stripped out. Either one of those could easily result in a crashed plane. With high torque servos prices coming down so much lately you can get good higher torque servos for not much money. Personally I wouldn't risk losing a plane over a few dollars in servos.
What servos are you consdering using??
Ken
What servos are you consdering using??
Ken
02-18-2010, 02:38 PM
#4
Thread Starter
RE: What are the risks of using 44 oz-in vs. 54 servos
Top Flite At-6 kit. No aerobatic flying. I would like to use Futaba 3001 servos (4 for about $25), but probably need the Futaba 9001 servos (1 for $35). I agreed it's not worth risking a crash, but I need 7 servos:
arlerons - 2
flaps - 1
elevator - 1
r=udder - 1
retracts - 1
throttle - 1
arlerons - 2
flaps - 1
elevator - 1
r=udder - 1
retracts - 1
throttle - 1
02-18-2010, 02:58 PM
#5
Senior Member
RE: What are the risks of using 44 oz-in vs. 54 servos
If you install boost tabs and be sure to have free hinges, you can easily get by. I've flown some very large planes with the old 32 inch/oz servos with no problems.If you are not familiar with "boost tabs" just
google for information. I believe Allen's Hobbys web site has some good info there on boost tabs.
google for information. I believe Allen's Hobbys web site has some good info there on boost tabs.
02-18-2010, 04:43 PM
#11
Senior Member
RE: What are the risks of using 44 oz-in vs. 54 servos
Just google "boost tabs" loads of info. Got me thinking. I'm about to start on a AMS P-61 and it uses some pricy servos. A little cut and snip and maybe it just might work. I think I'll try them on something more "expendable" first though.
Don
Don
02-18-2010, 06:05 PM
#13
Thread Starter
RE: What are the risks of using 44 oz-in vs. 54 servos
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
02-18-2010, 07:28 PM
#14
My Feedback: (20)
RE: What are the risks of using 44 oz-in vs. 54 servos
Scratchie, if you are worried about the torque, you will be better off reducing the control surface movement mechanically rather than using the low rate electronics on your radio. I just maidened an 81" span Val with OS 1.08 that has standard servos on the ailerons and flaps. It came through the first two flights just fine. Check out one of the on-line servo torque calculators; you'll be surprised how little torque is actually required for realistic flying speeds. here is a link http://www.csd.net/~cgadd/eflight/ca...vo.htm#formula
02-18-2010, 08:17 PM
#15
My Feedback: (-1)
RE: What are the risks of using 44 oz-in vs. 54 servos
Maybe I'm just getting old but it wasn't even 10 years ago that the 48 in.lb. servo was a big one. We started ganging them for giant scale but they still worked well for most any 60 sport plane. How big do you think the servos were in the Pattern Planes in the 70s and 80s. Standard servos are just fine for most any sport plane up to about 60 size.
02-18-2010, 09:23 PM
#16
RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: Gray Beard
Maybe I'm just getting old but it wasn't even 10 years ago that the 48 in.lb. servo was a big one. We started ganging them for giant scale but they still worked well for most any 60 sport plane. How big do you think the servos were in the Pattern Planes in the 70s and 80s. Standard servos are just fine for most any sport plane up to about 60 size.
Maybe I'm just getting old but it wasn't even 10 years ago that the 48 in.lb. servo was a big one. We started ganging them for giant scale but they still worked well for most any 60 sport plane. How big do you think the servos were in the Pattern Planes in the 70s and 80s. Standard servos are just fine for most any sport plane up to about 60 size.
Ken
02-18-2010, 09:24 PM
#17
RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: Scratchie
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
Those additional amps make the servos stronger.
Same battery will last less time in this proportion: 4.8 / 6.0
For same total flight time the capacity (mA-h) of the battery needs to be upgraded in this proportion: 6.0 / 4.8
http://www.radicalrc.com/4or5cellsfaq.htm
Just calculate the torque you need with this on-line calculator:
http://www.geistware.com/rcmodeling/calculators.htm
02-18-2010, 09:45 PM
#18
Senior Member
RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: Scratchie
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
It is common knowledge that digitals require more MAH. They may, but it isn't noticable. Iwas helping a new guy Saturdaywith a problem he was having and I was astounded athow slow his surface movement was.Icould go full up, full down and back to full up on thestick and the servo movement was about a half stick behind.Trying tofind center was also a bit of a chalenge. I would trima surfact to center and then wiggle the sticks,it wouldn't quite center again. trim half that out and wiggle the sticks and the average center would be OK.My vote is digitals on 6.V, followed with analog on 6V. I usually fly digitals on 4.8V though because I have more 4.8 V batteries.
Bottom line, go fly. You will go nuts trying for the "best", or "proper" set. Put some good batteries and good servos and go fly and enjoy it.
Don
It was foggy and cooler today, about 65, but the last week has been as good as you can get. 70 to 80 and near calm winds down the runway.
02-19-2010, 02:29 AM
#19
RE: What are the risks of using 44 oz-in vs. 54 servos
Best bang for the buck:
$15 (CAN) Each!
hitec 485
Carbonite gears & ball bearing
45 gWeight:
66.6 oz-inTorque @ 4.8V
83.3 oz-inTorque @ 6.0V
0.22 sec/60°Speed @ 4.8V
0.18 sec/60°Torque @ 4.8V
When I was flying my kadet Mk2 I remeber using hitec 325, 44oz servos. They worked ok, but I switched them out for hitec 475 (485 replaces the 475) I noticed a BIG differance in flight! Much more responsive. With the 44oz servos the elevator seemed lazy. I would never use anything below a 475-485 other than the 225 mini metal gear.
For a cheap servo on 6 volts they are awsome! and 66oz on 4.8v is pretty good too.
$15 (CAN) Each!
hitec 485
Carbonite gears & ball bearing
45 gWeight:
66.6 oz-inTorque @ 4.8V
83.3 oz-inTorque @ 6.0V
0.22 sec/60°Speed @ 4.8V
0.18 sec/60°Torque @ 4.8V
When I was flying my kadet Mk2 I remeber using hitec 325, 44oz servos. They worked ok, but I switched them out for hitec 475 (485 replaces the 475) I noticed a BIG differance in flight! Much more responsive. With the 44oz servos the elevator seemed lazy. I would never use anything below a 475-485 other than the 225 mini metal gear.
For a cheap servo on 6 volts they are awsome! and 66oz on 4.8v is pretty good too.
02-19-2010, 11:09 AM
#20
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RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: twn
Best bang for the buck:
$15 (CAN) Each!
hitec 485
Karbonite gears & ball bearing
45 gWeight:
66.6 oz-inTorque @ 4.8V
83.3 oz-inTorque @ 6.0V
0.22 sec/60°Speed @ 4.8V
0.18 sec/60°Torque @ 4.8V
When I was flying my kadet Mk2 I remeber using hitec 325, 44oz servos. They worked ok, but I switched them out for hitec 475 (485 replaces the 475) I noticed a BIG differance in flight! Much more responsive. With the 44oz servos the elevator seemed lazy. I would never use anything below a 475-485 other than the 225 mini metal gear.
For a cheap servo on 6 volts they are awsome! and 66oz on 4.8v is pretty good too.
Best bang for the buck:
$15 (CAN) Each!
hitec 485
Karbonite gears & ball bearing
45 gWeight:
66.6 oz-inTorque @ 4.8V
83.3 oz-inTorque @ 6.0V
0.22 sec/60°Speed @ 4.8V
0.18 sec/60°Torque @ 4.8V
When I was flying my kadet Mk2 I remeber using hitec 325, 44oz servos. They worked ok, but I switched them out for hitec 475 (485 replaces the 475) I noticed a BIG differance in flight! Much more responsive. With the 44oz servos the elevator seemed lazy. I would never use anything below a 475-485 other than the 225 mini metal gear.
For a cheap servo on 6 volts they are awsome! and 66oz on 4.8v is pretty good too.
02-19-2010, 12:26 PM
#22
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RE: What are the risks of using 44 oz-in vs. 54 servos
As far as I know, mfg. servo torque is with a 1" arm on the servo. Think leverage here. A long cheater bar works way better than a short one. Use the longest one you can fit in the space you have.
And, yes, most applications do not need as much torque as most folks are led to believe.
And, yes, most applications do not need as much torque as most folks are led to believe.
02-19-2010, 12:48 PM
#23
My Feedback: (-1)
RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: Campgems
Higher voltage means higher amps drawn. Ohm's Law. Given a 4.8V and a 6V battery of the same MAH, the six vold will provide more torque, and faster speed, but shorter flight time. If you are flying low MAH batteries, this can be a problem, but with 2400MAH NiMh batteries, you will tire before the battery does.
It is common knowledge that digitals require more MAH. They may, but it isn't noticable. I was helping a new guy Saturday with a problem he was having and I was astounded at how slow his surface movement was. I could go full up, full down and back to full up on the stick and the servo movement was about a half stick behind. Trying to find center was also a bit of a chalenge. I would trim a surfact to center and then wiggle the sticks, it wouldn't quite center again. trim half that out and wiggle the sticks and the average center would be OK. My vote is digitals on 6.V, followed with analog on 6V. I usually fly digitals on 4.8V though because I have more 4.8 V batteries.
Bottom line, go fly. You will go nuts trying for the ''best'', or ''proper'' set. Put some good batteries and good servos and go fly and enjoy it.
Don
It was foggy and cooler today, about 65, but the last week has been as good as you can get. 70 to 80 and near calm winds down the runway.
ORIGINAL: Scratchie
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
I know hifgher voltage will yield higher torque, but are there negative ramifications of higher voltage?
It is common knowledge that digitals require more MAH. They may, but it isn't noticable. I was helping a new guy Saturday with a problem he was having and I was astounded at how slow his surface movement was. I could go full up, full down and back to full up on the stick and the servo movement was about a half stick behind. Trying to find center was also a bit of a chalenge. I would trim a surfact to center and then wiggle the sticks, it wouldn't quite center again. trim half that out and wiggle the sticks and the average center would be OK. My vote is digitals on 6.V, followed with analog on 6V. I usually fly digitals on 4.8V though because I have more 4.8 V batteries.
Bottom line, go fly. You will go nuts trying for the ''best'', or ''proper'' set. Put some good batteries and good servos and go fly and enjoy it.
Don
It was foggy and cooler today, about 65, but the last week has been as good as you can get. 70 to 80 and near calm winds down the runway.
Today I have a lot of servos, both digital and analog, I don't even worry about mixing them. I have used a lot of standard servos in some very high performance planes. They may not be as fast or hold as well but they are cheap. When I had some deeper pockets I did start buying digitals but I started out using the low end Hitecs then worked my way up. I always go to different sites like Servo City to see what is on sale or close out. Once I scored real heavy on a close out of high end servos.
Over cast with some wind, about 74 today?? That's what they are telling me anyway. This storm is moving in fast and we are supposed to get a lot more rain out of it. Forcast is nasty for about a WEEK!! Just doing R&R on some of my planes. Grounded due to the Pres. You know the guy, the don't go to Vegas and spend your money person!!
Here he is!! Messing up the RC pilots again.
02-19-2010, 12:57 PM
#24
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RE: What are the risks of using 44 oz-in vs. 54 servos
For sport flying consider 1.0 oz. in. of torque for every square inch of control surface. For example, if your rudder area has 35 square inches, you should feel okay with 35 oz. in. of torque. If you can match this, go fly and feel comfortable.
02-19-2010, 01:44 PM
#25
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RE: What are the risks of using 44 oz-in vs. 54 servos
ORIGINAL: twn
I didn't know that hitec went with a single bearing on the 485 I thought they were dual like the 475.
I didn't know that hitec went with a single bearing on the 485 I thought they were dual like the 475.
They list the 485 as "top ball bearing", the 475 used to be listed as "Dual Ball Bearing". Of course, in searching for the 475 on their site, it now says it was top ball bearing also.
From their website: http://www.hitecrcd.com/servos/show?name=HS-485HB
HS-485HB
HS-485HB updates the very popular HS-475HB by adding more torque and greater speed. With a top ball bearing, heavy duty, high impact Karbonite™ gears and high performance circuitry, the HS-485HB offers lots of torque and features excellent centering and resolution.
*See Karbonite guidelines below
Detailed Specifications
Motor Type: 3 Pole
Bearing Type: Top BB
Speed: 0.20 , 0.17 sec @ 60 deg.
English Metric
Torque: 72 / 89 (4.8v / 6.0v)
Detailed Feature Descriptions
Applications: Heli's and Aircraft up to 72” or up to 12lbs when using just one servo per control surface.
Note: Be aware that high vibration gas (not glow) engines combined with large contol surfaces and large thows (3D models) can put undue strain on the gears. Metal geared servos are recommended for these applications even if under 12lbs.
Warning: Do not use thread lockers on Karbonite geared servo as it will cause the output shaft to fail.