Servos?

[Mike S]

As the title says I am intrested in the brand and model of servos that you all use in your aircraft.

I am trying to decide on the servos to buy for the P47. I normally use either Futaba S148's,3001's or 3003's. These have done me well in my old Wot trainer and I have some in my Pawnee 40. They fine for the these aircraft that potter around the sky but wonder if there up to the job for the P47.

[simonh]

I'm using S148's in the Sbach342  - for the Ailerons and elevator. I'm using an S3010 for the rudder as it uses pull - pull cables so a ball raced higher torque servo seemed a good idea. Its a highly aerobatic 3D plane and I think the S148's will do the job. Will let you know for sure after the maiden

[Gareth]

Mike,

If you look at the age of th plan it was designed for 148's or equivalent. I know some of these models have been built using hs-81's or similar. These have the same pull, slightly faster and much lighter then the 148's. Just some thing else to throw in the pot. If you are still to build the servo bays this would be q very simple upgrade.

[Mike S]

Gareth.

Was looking in to the Hs-81 servos. It seems the Hs-82 both resin and metal gear have replaced the Hs-81's.

The Hs-82's are the same dimensons as the Hs-81 and the Hs-82mg are £12.40 each.

Hs-82mg specs

Operating Speed (4.8V): 0.12sec/60° at no load
Operating Speed (6.0V): 0.10sec/60° at no load
Stall Torque (4.8V): 38.80 oz/in. (2.8kg.cm)
Stall Torque (6.0V): 47.12 oz/in. (3.4kg.cm)
Ball Raced: No
Weight (grams): 0.67oz (19g)
Dimensions (mm): 12.0 x 29.6 x 29.8

These should work ok with the P47. Think about what we talked about this morning to do with vibration from the engine this servo should be ok for the Laser 100?

[andyb]

It's got a noise-maker up-front, so there'll be lots of vibration. Under those circumstances, I think you probably need some... Blood and sand! I've just looked at the price of servos!

...I think you'd probably be best with some ball-raced standard (i.e. S148-sized) servos with robust gear-trains, I think Futaba S3001s will be fine, won't break the bank and will last a long time. If you're paranoid, use a better servo for the elevator (not the rudder - you can do without a rudder...)

[Mike S]

Andy.

I have some s148s, 3001 and 3003 servos which I can use for the throttle but are plastic gears. I do have a ds620 metal gear digital servo which was designed for helicopter use so should handle vibration and gear wear very well but is a bit of an overkill.

My current plan is to use separate servos on the following, elevator, flaps and ailerons. Using the Hs-82's will reduce weight and allow me to fit all the servos in with out a weight penalty.

All all I need 9 servos:

9x standard size servos @ 48g = 440g's
8x midi servos @ 19g + 1 standard size servo 48g = 200g

At the moment I have I considering all options so I am open minded about any suggestions.

[andyb]

OK, if you want to use HS-82s on most surfaces you'll be fine (nylon-geared servos are fine for something with an undercarriage), but I implore you not to use one on the elevator - if that goes, you're scr*wed. Pick a relatively new standard-sized, ballrace servo (that's had a bit of burn-in) from a reputable manufacturer and retailer.

[Gareth]

Mike,

I know i said yesterday that most Gas engines require metal gear servos, this is more at the petrol models. I would have thought that a standard servo on a 4st would be ok as the vibrations should be smoothed out.

Gareth

[Mike S]

OK, if you want to use HS-82s on most surfaces you'll be fine (nylon-geared servos are fine for something with an undercarriage), but I implore you not to use one on the elevator - if that goes, you're scr*wed. Pick a relatively new standard-sized, ballrace servo (that's had a bit of burn-in) from a reputable manufacturer and retailer.

Andy.

I was planning on using the HS-82 metal gear version all round apart from the throttle and I was am also planning on using two hs-82's on the elevators rather than one servo.

I open to ideas. Andy which servos would you suggest as I am interested in which ones everyone have found to be reliable. I am a fan of the 148's etc but wanted to know what others where using.

[Mike71]

Hi Mike ,

I use futaba S3152 for most things . They are the entry futaba digital servo, 6 odd kg at 6v. I never had a problem with them even doing high speed flick manoeuvres on my larger Extra.

I think it's important to remember that a fast model needs a powerful servo more than a slow highly manoeuvrable model, and that it's pointless attaching a powerful servo to a control run with a load of slop in it. I'm sure 148s would do your P47.

Mike

[andyb]

Actually, I think Mike has a couple of good points. If it was me, I'd go for 148s all round with a ballraced version on the elevator. Personally, I used JR DS 811s and the equivalent Spektrum DS 821s, they're very, very good but they're now far too expensive.

Also, couple of other things;
1. Two servos are not twice as reliable as one  .
2. One big set of gears is much more robust than two smaller sets.
3. Metal geared servos are usually a waste of money on something like the P-47, and they'll have more slop than nylon gears.
4. It's not necessarily the case that a smaller servo will have a lower power consumption than a larger, standard-sized servo. All that performance has to come from somewhere...