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HelicopterMain Discussion › Actual Servo Speed Under Load
09-10-2007 10:48 PM  10 years agoPost 1
RockohaulicrrElite Veteran - Canyon Country, CA,​USA, 3rd Rock from​the Sun - My Posts: All  Forum  Topic

Hey guys, here is some interesting info about servo speed under load. What we need is to find out is what is the actual load on our cyclic servos.

The formula for servo speed under load = S/(1-L/T), where

S = Rated Speed at Zero Load
T = Rated Servo Torque
L = Assumed Actual Load

As you can see from the chart, a slower, higher torque servo can be faster than a high speed servo at certain loads.

Again, the problem is I don't know what the actual load is, so if anyone has ever come close to determining this, let me know. It would be interesting to determine once and for all which servos are best for our cyclic application.

I calculated the servo speed for 3 different loads in this chart...

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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09-10-2007 11:04 PM  10 years agoPost 2
Al Austria

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Gainesville, FL

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NICE WORK! Very cool to see these numbers.

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09-10-2007 11:07 PM  10 years agoPost 3
eyeflyhelis

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charlotte nc

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mount the servo on a small scale have it press down read the weight and you can calculate the load from that

only you have the power to make no difference!

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09-10-2007 11:09 PM  10 years agoPost 4
Al Austria

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Gainesville, FL

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I think he means actual IN FLIGHT loads.

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09-10-2007 11:14 PM  10 years agoPost 5
Rockohaulic

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Canyon Country, CA,​USA, 3rd Rock from​the Sun

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mount the servo on a small scale have it press down read the weight and you can calculate the load from that
No, the question isn't how much load can the servo handle, we know that from the specs, the question is, how much load does our helicopter actually place on the servo during flight.

For example, if my 50 size heli with CCPM is only placing a max load of 50oz-in during a flight, then I know that I can get the max response out of my heli with Hitec 6965 servos.

However, if my heli is actually placing a max load of 70 oz-in during a flight, then I can get the max response with Futaba 9351s.

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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09-10-2007 11:15 PM  10 years agoPost 6
Rockohaulic

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Canyon Country, CA,​USA, 3rd Rock from​the Sun

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I think he means actual IN FLIGHT loads.
You type faster than me.....................

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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09-10-2007 11:25 PM  10 years agoPost 7
eyeflyhelis

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charlotte nc

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i think i heard of an inline analyzer but i'd have to look for it. it would tell you the response times and loads but if i remember correctly it was very costly

only you have the power to make no difference!

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09-11-2007 12:38 AM  10 years agoPost 8
HugeOne

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Quebec, Canada

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Those guys have tested over 164 servo and built a big database within this software.
Website:
http://www.teaser.fr/~osegouin/aeromode/servos.phtml
Software:
http://osegouin.free.fr/servo/servo...22_mai_2007.zip

-Hugo

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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09-11-2007 02:39 AM  10 years agoPost 9
tchavei

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Portugal

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Glad I have the 9351 after all

Tony


--------------------
"Perfection and patience usually walk side by side..."

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09-11-2007 04:52 AM  10 years agoPost 10
ShaneAllen

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Irving, TX

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I second the 9351. I was worried I had enough torque, but not enough speed with my 9351s, but now I see I probably have both......
No wimpy servos allowed.....

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09-11-2007 05:08 AM  10 years agoPost 11
Nick Jones

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anderson

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I bet the jr 8717 are insane

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09-11-2007 06:07 AM  10 years agoPost 12
RjX of USA

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IL

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8717

I bet they are a very good felling servo in the air, but my 9351's are to for a lot less.

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09-11-2007 06:37 AM  10 years agoPost 13
QuantumPSI

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Atlanta, GA

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My only question is, where did that formula come from? Not that I doubt it, just curious...

As for in flight loads, I've been wondering this for quite sometime now. The interesting thing is that it would different for different helis because of different dimensions in the head. Knowing this information could add a whole new dimension in defining the performance of our machines...

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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09-11-2007 07:00 AM  10 years agoPost 14
Anthony.L

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Seattle, WA

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There has always been a rumor that top Futaba pilots choose the 9351 over the 9451 because under load the 9351 was actually faster. Interesting to finally see some data to support this, and glad I bought 9351's!

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09-11-2007 07:17 AM  10 years agoPost 15
JAGNZ

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Auckland, New​Zealand

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Loving the 9351's here too...


Jason Greenwood

www.3dheli.co.nz

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09-11-2007 07:50 AM  10 years agoPost 16
THX1138

rrElite Veteran

Camp Bondsteel,​Kosovo

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Very well done bro. Good info to have.

Lou

Just give me five dudes and two flashbangs...

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09-11-2007 09:15 AM  10 years agoPost 17
no1pylon

rrApprentice

Chorley, UK

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Could you put a datalogger on and detect how many amps they are pullling in flight and then compare it to placing weights on the servo arms?
Not sure if this is possible just an idea

Check my Gallery

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09-11-2007 02:01 PM  10 years agoPost 18
SSN Pru

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Taxachusetts

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Could you put a datalogger on and detect how many amps they are pullling in flight and then compare it to placing weights on the servo arms?
Agreed. A good way to experimentally derive the loads during flight.

I bet the load on the servo could be calculated after taking some in flight current readings on one cyclic servo. It would take some math and experimenting but I think it could be done.

Stupidity can be cured. Ignorance is for life!

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09-11-2007 02:30 PM  10 years agoPost 19
JKos

rrProfessor

Redondo Beach, CA

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Maybe something like this: http://www.dimensionengineering.com/ServoSensePlus.htm

Or the next step up like this:
http://www.eagletreesystems.com/MicroPower/micro.htm

- John

RR rules!

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09-11-2007 02:34 PM  10 years agoPost 20
gullie667

rrVeteran

Brooklyn, NY

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Couldn't you just stick an amp draw meter on a servo and record that during a flight, then use the scale method to reproduce the amp draw?

Helicopters - 1000 parts flying in formation.

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HelicopterMain Discussion › Actual Servo Speed Under Load
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