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STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

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Old 09-15-2008, 05:51 PM
  #1
airbusdrvr
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Default STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Are there any major issues using a standard servo in place of a retract servo if the torque requirements of the system are met? For a 60 size airplane with retracts I am considering using a higher torque standard servo. The reasoning is that travel adjustement is available with a standard servo. The retract servos turn 180 degrees from up to down. With a standard servo this amount can be adjusted with the transmitter. I am concerned about perhaps unknowingly setting up a standard servo that might have a load on it after reaching the up or down position. Could this cause a constant amp draw that could reduce battery life during the several flights between receiver battery charging? I would think if set up properly and no excessive load on the servo in the up or down position, then the standard servo should draw little if any power. I need other more experienced ideas.
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Old 09-15-2008, 06:52 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Standard servos are designed to move 60 degrees. I know that you can increase the ATV up to 150%, on an XP9393 Tx, but I do not know how much more travel that gives you. 60+30=90 I supposes, but I set up my big birds to 150% and I do not remember them traveling out to 90 deg. That would be unusable for normal pushrod use.
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Old 09-15-2008, 07:24 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Standard servos can be set to travel enough for 60 size retracts. I have done it with no problems that I was aware of. I was hoping to hear from others that might have used them to see if they, too, had no problems. Sometimes it is a pain to find just the right distance out on a retract servo control wheel to drill the hole to get just the right amount of travel. Whereas, with a standard servo, travel can be transmitter adjusted to the right amount of up and down travel. I guess I would have to do a retract setup and then check amp draw after the standard servo was fully up or down and see if there was more than normal amp useage at rest.
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Old 09-15-2008, 07:41 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

I have a H9 P47-150 that came with Mechanical Retracts, but one servo is installed in each Retract Mechanism. It was just a matter of picking the right length of Servo Arm. I needed the JR 791 Retract Servo, because the RT88 did not have enough torque and also easily stripped a gear.

Back in the 80's, I used to use Mechanical Retracts, with one Retract Servo and two Pushrods. Once again, it was just a matter of the diameter of the Servo Arm. Just like Throttle Adjustment, before Endpoints came along, the process of Mechanical Adjustments is somewhat tedious and frustrating, at times.

I will be switching to Robart Air Retracts, for this plane, in the future. My other planes, that use Retracts, all use Air Retracts. There were no Air Retract alternatives when I first bought the H( P47-150.
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Old 09-15-2008, 08:44 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Two + 1 reasons to use retract servo in lieu of a standard servo:
1. On/Off 180 degree strong operation - less chance of overload failure than with a standard servo on EPA out to max.
2. Most retract servos have a very low profile to better fit into wing.
+1. A Hitec digital servo can be programmed with a HFP-10 or HFP-20 to act as a retract servo.
Hitec GS-75BB Retract Servo Specifications
Hitec HS-5645MG Sport Digital Specifications
Refer also sub section "Retract Undercarriage, Flaps and payload release" at
Alan's Hobby, Model & RC FAQ Web Links
Regards
Alan T.
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Old 09-15-2008, 08:46 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

which warbird do you have?
On my H9 60 P-51 the servo must travel far enough of lock the gear up or down. A stardard servo will not travel enough to lock the gear.
Granted that that is on hanger9, i am not to fimiler with other brands and how they retract.

My 2 cents.
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Old 09-15-2008, 08:52 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

That is the way my H9 P47-150 Retracts work, as well. I forgot about that.
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Old 09-16-2008, 03:50 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

A retract servo moves 180 degrees and shuts off so you don't stall it and suck the battery down.

Measure the throw of the retract mechanisim pushrod.

Use that measurment to drill two holes, 180 degrees apart across the center of a servo wheel (a blank wheel is much stiffer than a horn with arms, and a blank one lets you drill holes so the measurement is exact, which is what you want)

Thats all you need and then you won't get any stalling and the gear will be locked full up and down.
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Old 10-28-2008, 09:35 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????


Quote:
ORIGINAL: A.T.

Two + 1 reasons to use retract servo in lieu of a standard servo:
1. On/Off 180 degree strong operation - less chance of overload failure than with a standard servo on EPA out to max.
2. Most retract servos have a very low profile to better fit into wing.
+1. A Hitec digital servo can be programmed with a HFP-10 or HFP-20 to act as a retract servo.
Hitec GS-75BB Retract Servo Specifications
Hitec HS-5645MG Sport Digital Specifications
Refer also sub section "Retract Undercarriage, Flaps and payload release" at
Alan's Hobby, Model & RC FAQ Web Links
Regards
Alan T.
will the programmer allow you to slow down the servo to make the retract act slower
?
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Old 10-28-2008, 09:53 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Hitec Digital Servo Programmer xontrols =

Servo Tester Features: Check Any Brand of Servo with a Manual Test and Auto Scan. Plus Check the Pulse Width and Voltage.

Here is the comparison chart between the programmers and Hitec digital servos.
Servo Test & Programmable functions of old HFP-10:
Manual and Automatic testing procedures, Transmitter Pulse width measurement, Receiver Voltage measurement,
Direction of Rotation, Speed of Rotation, Fail Safe On-Off, End Point, Neutral Point, Fail Safe Point Preset
Servo Test & Programmable functions of New HFP-20:
Basically Same as old HFP-10, and "Overload protection Setting" and "Servo Resolution mode Setting" Function added.


Programmer........Function...................Conve ntional........HS-50xx..........HS-7xxx
.................................................. ..........HS-5/6xxx.........Digital Micro.....Digital
.................................................. ..........Digital Servos......Servos............Servos
HFP-10 & 20......Servo Test...............................Yes..........Ye s.................Yes
.........................RX Pulse & Voltage Measure....Yes..........Yes..................Yes
.........................Reset.................... ..................Yes..........Yes................ Yes
.........................Dead Band Setting...................Yes..........Yes........ ........Yes
.........................Servo Speed............................Yes..........Yes. ..............Yes
.........................Change Rotation (CW/CCW).....Yes..........Yes......... ......Yes
.........................Fail Safe On/Off.......................Yes...........Yes....... ........Yes
.........................EPA/Fail Safe Position.............Yes...........Yes............ .....Yes
.........HFP-20
........................Overload Protection...................No.............Yes... ...........Yes
........................Resolution Mode Setting............No..............No............. ..Yes

G2 The Second Generation Premium Digital Servos (HS-7XXX series)
*Overload protection : This function is to protect the servo(HS-50XX servos & HS-7XXX servos) from the overload condition. Once the servo is forced with overload condition for certain time, the motor output will be decreased to the setting level set by user. Please note that this function is deactivated (off) in factory setting.(factory default : overload protection off)
*Resolution mode setting : There are two resolution modes(High and Normal) in HS-7XXX servos. Factory default is set at "High" resolution, and servo travel will be 120 degree. If user needs to widen the servo travel, user may select ë°ˇormal?resolution so that the servo travel can be widened to maximum of 180 degrees.
(Factory default : Resolution mode High)
"NOTE" : These new functions (Overload protection Setting & Resolution Mode Setting) can be programmed by new Hitec servo programmer, HFP-20.

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
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Old 10-28-2008, 11:50 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

I slow my JR791 Retract servos with my JR XP9303 Tx
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Old 10-29-2008, 06:00 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Alan, as always, a wealth of good info.
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Old 10-29-2008, 10:17 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????


Quote:
ORIGINAL: BuschBarber

I slow my JR791 Retract servos with my JR XP9303 Tx
I was all set to do that with my scale sailplane only to find out to my dismay that the servo slow down feature isn't available in the sail plane menus [sm=confused.gif]
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Old 10-29-2008, 11:11 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

I don't understand how you can do that, the JR791's are non proportional, am I missing something here[:-]
Pete
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Old 10-29-2008, 01:01 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

All I know is that it works. Perhaps it is just adding a Delay so that one gear goes up After the other. My Retract servos are on separate channels and mixed to accommodate this effect.
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Old 06-04-2013, 09:44 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Buying a tucano 60 with mechanical retracts installed.needs 2 low profile retract servos .setting my futaba super8fg.need to decide on torque onces and a brand.plane weighes 7 to 9 pounds?thanks
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Old 06-04-2013, 10:58 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????


Quote:
ORIGINAL: pilotpete2

I don't understand how you can do that, the JR791's are non proportional, am I missing something here[:-]
Pete
It is the Delay feature that allows one gear to go up before the other.
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Old 06-04-2013, 05:00 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

WOW, almost 5 years for that comeback Rich
You're right of course
Pete
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Old 06-04-2013, 06:00 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????


Quote:
ORIGINAL: pilotpete2

WOW, almost 5 years for that comeback Rich
You're right of course
Pete
I like to be Timely!

Actually, I read the latest reply to this thread and saw what I had written before, so I corrected it.

Thanks!
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Old 06-05-2013, 07:21 AM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

Servo city has a device that will make any standard servo into a 180 degree servo
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Old 06-07-2013, 08:15 PM
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Default RE: STANDARD SERVO FOR MECHANICAL RETRACT-GOOD OR BAD IDEA????????

OR.....you could modify a standard servo to travel 180 degrees by adding two resistors into the feedback pot circuit. Here's an article I wrote many years ago about modifying a Futaba 148 to operate the retracts in an old Ultra Sport 40 ARF. 180 servos also work great for flaps.

http://mypage.yhti.net/~dmcdnld/s148retract.htm

I used the same technique to modify some TowerPro 995 servos to run the retracts in a 60 size H9 Hellcat and 60 size H9 P-51. The TowerPro 995 is a digital metal gear servo that only cost about $10. I don't care for them on control surfaces, but they work great as retract and flap servos.
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