Hey

Can anyone tell me what size servos I need for my 80' Extra, it will have an SC 180ar 2 stroke on it, and will weight just over 14lbs - I am currentyl using Hitec HS 475HB servos on 6v which gives 76oz/in - I have was hoping to have these on all sufaces, except forthe rudder which i will get something bigger on?
Will these do the trick?

ANy help would be great!

cheers

RJ

I don't claim to be a servo expert but last night I was going through the servo threads and saw lots of post about the hb gears not holding up to hard flying
I'm not saying there no good but most people leaned toward metal gears for the bigger birds
I'm putting a 80 big boy together and will be using hs645mg 133 oz@6v for all the surfaces I know there not coreless digitals but at my level of flying I'm not sure I'd notice the
differance but maybe they would turn me into a better flyer then I am but for now I'll stick with the 30 dollar ones. I might try better ones when I get around to building a more percision plane

Thanks for the reply.

My flying is not to hard out, so i am really hoping these servos will cope! Any idea if there is a metal upgrade pack I can buy for my Hitecs?
Anyone else out there have an opinion?

RJ

Yes, I have an idea, but you won't like it. You really need to look at the load you will be putting on the gear train and the servo itself. If you are determined to use these servos, then at least use two on each aileron, and one for each elevator half. The rudder will require a stronger servo, so yu have already decided to do that. I would reccomend going with a better servo than the 475's. After all, you can use them again, and with servo's there is no such thing as too good. You are spending a good amount of money on this model, so why cut corners at this stage? Go ahead, break your budget, and get the good stuff.

Bill, AMA 4720

I would go with metal gear servos. As far as I know, there is no metal gear upgrade for the servos you list. I would shelf those karbonite servos you have (or sell them on ebay) and pick up hitec 625/645MG or digital 5625/5645MG's. They are going to be the most economical route as far as quality metal gear servos, and as long as your aren't doing alot of 3D the 645mg's would work fine and are really inexpensive. If cost doesn't matter as much, then get the 5925/5945's. I would put a hitec 5955TG on the rudder. Yes, its big bucks, but then again so is the rest of your plane and engine.

All I can say from first hand observation of many different applications is that karbonite gears are crap.

Hey all,

Just I as had decided to suck it up and go and buy 5 new Hitec 645MG's - I saw some Towerpro MG995 for sale - I have had a quick look on some forums and there are mixed reviews - I am 95% going to stick with the Hitec's - although if someone out there had some in a large scale Aerobatic plane and rated them highly - then just maybe.... I might change my mind????

Anybody got any feedback on them???

RJ