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Servos Selecting An Aftermarket Servo

BCJ

Member
I have an FMS plane that blew out one of its aileron servos.
It's an FMS 091; see photo

The problem is that this servo is evidently no longer available.
How do I select a replacement servo that is compatible? (Spektrum TX and RX)
 

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D.O.G.

Well-Known Member
Goblin 380 Supporter
Have you tried HobbyKing "USA", Flight test and AMain Hobbies. They have decent servos for cheap.
 

Admiral

Well-Known Member
If its one of a pair I would replace both so that you have the same speed and strength, then you need to get one the same dimensions so that it will fit in the same location.
The brand will depend on how much you want to spend, it's basically a standard 9g analogue servo, probably better to buy a digital replacement.
 

Tony

Administrator
Staff member
I am with Admiral on this one. Definitely replace the servos as a pair. Since they are aileron servos, I would honestly stick with plastic gear just to keep the weight down, but I would definitely go digital. There is just so much more resolution to them and they are faster than analog (this is the correct way to spell analog, Aussie's have it all wrong hahaha :poke: )
 

BCJ

Member
I am with Admiral on this one. Definitely replace the servos as a pair. Since they are aileron servos, I would honestly stick with plastic gear just to keep the weight down, but I would definitely go digital. There is just so much more resolution to them and they are faster than analog (this is the correct way to spell analog, Aussie's have it all wrong hahaha :poke: )
Thanks, guys.
I'll definitely replace both. It makes total sense that the two aileron servos are the same.
Now I just need to find servos of the same size and specs. BTW, how important is it that the specs are exactly the same as the four sets of numbers shown on the servo label (some of which, frankly, I do not fully understand).
 

Tony

Administrator
Staff member
Other than physical size, the specs can (and should) differ. You want faster, you want stronger, and it's nice to find one that can handle more voltage, although you are likely not going with a high voltage setup for them on this plane.

I know I stated to stick with plastic gear, however the best servo I have found that is cheap is the EMAX ES08MD. They have come out with the ES08MDII, however I do not see any updates to speed or anything. I have used these on "Budget Builds" and they work great, and center quite well for their price. You can also get them in a 6 pack if you plan on using more. And in a plane, you will likely never break one of these servos.

Emax ES08MDII Metal Digital Micro Servo for RC Models RC Parts from Toys Hobbies and Robot on banggood.com <-- this is the USA Warehouse, not the China warehouse
 
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BCJ

Member
First, a note to the Admiral: I'm tri-lingual and one of my languages is Strine, so go ahead and talk in your native language; i'll translate for Tony if necessary ! LOL

Tony, that servo looks good and it's inexpensive ($7 each in the two pack). Just to be sure about the Emax ES08MDII Servo . . .

Size: 23mmx11.5mmx24mm -- the old is 22mm instead of 24 but that shouldn't be a problem (??)

Speed: 0.12sec/60° at 4.8V; 0.1sec/60° at 6V -- the old one is a touch faster: 0.11/0.09. Issue?

Torque : 1.6 kgf.cm-4.8V,2.0 kgf.cm-6.0V -- the old one has less torque: 1.2 / 1.5. Issue?

Weight: 12g -- the old one is 9g, so this would add a total of 6 grams. Problem?

Designed for : All 450 Class Helicopters -- but is it still ok for fixed wing?
 

Tony

Administrator
Staff member
size, shouldn't be an issue, may need to do some trimming to make it fit. This is just the length of the case I believe.

speed, I don't think you will notice a difference in speed. The strength more than makes up for it.

torque, more is better.

weight, these are known as 9g servos because when they first came out, they were 9g. Since the emax is a little larger and has metal gears, it is going to weigh a little more. 3g*2 is not going to make much if any difference and is a great upgrade to metal gears.

they say for helicopters because that is the stock size for helicopters 450 (325mm blades) or smaller. It will work just fine for an airplane.

As for speaking multiple languages, I speak 2... English and Bad English. I'm fluent in the latter. :chuckles:
 
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BCJ

Member
size, shouldn't be an issue, may need to do some trimming to make it fit. This is just the length of the case I believe.

speed, I don't think you will notice a difference in speed. The strength more than makes up for it.

torque, more is better.

weight, these are known as 9g servos because when they first came out, they were 9g. Since the emax is a little larger and has metal gears, it is going to weigh a little more. 3g*2 is not going to make much if any difference and is a great upgrade to metal gears.

they say for helicopters because that is the stock size for helicopters 450 (325mm blades) or smaller. It will work just fine for an airplane.

As for speaking multiple languages, I speak 2... English and Bad English. I'm fluent in the latter. :chuckles:

Thanks man!
You're amazingly helpful.
And congrats on being bi-lingual!
 

Tony

Administrator
Staff member
It's my pleasure bro! Let us know if there is anything further that we can help out with. And we will need video of that plane in the air with the new servos. lol
 
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Admiral

Well-Known Member
First, a note to the Admiral: I'm tri-lingual and one of my languages is Strine, so go ahead and talk in your native language; i'll translate for Tony if necessary ! LOL

Thanks Cobber, some of those tin tanks do get confused with our brand of English. LOL
 
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BCJ

Member
It's my pleasure bro! Let us know if there is anything further that we can help out with. And we will need video of that plane in the air with the new servos. lol
OK . . . will try. Photographing flight is tough. I tried once (with the wife as photog) and it was -- uh uh -- not so successful!

BTW Tony, may I ask what part of the country you call home?
 

Admiral

Well-Known Member
A quick question from your friendly linguist:
Is there a difference in meaning / usage between "cobber" and "mate" ?

No same meaning, different generation probably, I only use Cobber when I'm trying to sound Oka, I notice the younger generation are starting to use BRO which has been introduced in the last 20 years by he KIWIs & Islanders that have moved here.
 

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