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Servo Selection Help Please

Old 10-21-2011, 02:16 PM
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Default Servo Selection Help Please

I'm looking at getting the Hanger 9 P-51 Mustang 40 Sport ARF reviewed here in RCU. For servos, the reviewer used the suggested JR DS-821 servos. Digital and high torque. Are these necessary?

Here's why I ask. I've been building and flying since the mid 1970s and have always pretty much used the servos that came with the radios. I currently fly a few larger planes and have never seen the need to use the higher torque servos. I fly an old Areomaster Special that's about 20 years old (remember when we actually built these things?) with a Super Tigre 60 and all Airtronice 94102 servos. I also fly a Goldberg Tiger 60 with a Super Tigre 75 and also all Airtronics 94102 servos. My last really "larger" (and newest) plane is a Hanger 9 Toledo Special with an Evolution 46 and Hitec HS-322HD servos in the body and HS-425BB servos on the ailerons. I can add that all of my flight pack batteries are 700 to 800 mAh pack by Hangtime (NoBS Batteries) Hobbies (do higher torque servos require larger flight batteries?).

So here's the question. Have I just been very lucky so far with these lower torque servos on my larger planes (I have yet to have a servo fail in all the years I've been building/flying) or are they fine to use so long as you're not either flying 3D and/or large gas powered planes? I guess that it would also help to add that being a "seasoned citizen" I tend to fly my planes at a slower pace, as I've got all day to do it and no particular place to be at any specific time.

My initial thought for servos for the P-51 Mustang was to go with the HS-425BB if lower torque is sufficient, or the HS-485HB if the recommendation is for higher torque units. Any other suggestion from those of you with servo knowledge/experience would be welcome.
Old 10-21-2011, 02:38 PM
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Default RE: Servo Selection Help Please

For sport flying on 40 / 46 size models Ihave always had good luck with Hitec 422 or 425bb servos. I do not know why you would need a high torque servo.

You do not say what type battery or cell qty you have but 800 mah see very low to me.Igenerally use 1200 mah nicads. Since Iwent to 2.4I have started to convert to 1200mah 5 cell , 6vdc packs

Good luck!
Old 10-21-2011, 06:50 PM
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Default RE: Servo Selection Help Please

[8D]I see no reason for the reviewers recommended JR servos.

However, for about $4 more, per servo, I would go with the Hitec 485's vs. the 425's.
Last, but not least, you can't go wrong with Hitec servos.
Old 10-22-2011, 04:14 AM
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Default RE: Servo Selection Help Please

Any standard 40 oz $10 servo will work just fine. For extra zip, run 6 volts, You will use about 50 mil amp per flight to guide you to battery size.
Old 10-22-2011, 05:44 AM
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Default RE: Servo Selection Help Please

My brother and I fly 40 and 60 size sport planes. Nothing radical or super fast. We have/had 40 and 60 size trainers and big stiks, astro hogs, super sportster 60, corsair 40, AT-6, uproar 60s, hog bipe, etc.

We use 72mhz ppm receivers, 4.8 volt 700 mah nicads, and 4 or 5 HS-425BBs (or the servos that came with the radios) in everything.

We usually charge overnight, fly as much as we want, and rarely need to use the field charger. Sometimes a flying opportunity comes unexpectedly and we use the field charger for everything.
Old 10-22-2011, 11:41 AM
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Default RE: Servo Selection Help Please

You do not need higher torque servos. But digital servos will give you more precise control due to the smaller deadband. You might like it better.
Old 10-24-2011, 11:38 PM
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Default RE: Servo Selection Help Please

The DS 821 is a standard size digital "sport" servo with plastic gears. Other servos are as good or better for the price.
I just used them because they were specified in a couple of ARFs. If I had to build the ARFs again, I'd likely use Hitec BBMG servos or later JR/Spectrum

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