I have to order servos for a Carl Goldberg Ultimate biplane. I have a Futaba 7C 2.4GHz radio. If I plan on flying it aggressively eventually, what type servos should I order?
Are [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHKB0&P=ML]digitals[/link] overkill for a setup like this? Any disadvantages to the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&W=001615334&I=LXVW07&P=K]standard[/link] servos?

I also don't know how many servos I need. I bought the plane used and it has aileron servos already inside the wings. I need all the rest of the servos. I'm thinking three - one for throttle, one for rudder/tail wheel and one for stabilizer, right?

Also, is there any alternative to using a Futaba receiver that's less expensive?

Sorry if these are stupid questions but I really don't know and could use some advice.

Thanks in advance.

I have the 60 size Goldberg Ultimate....It takes 5 servos: 2 ailerons (with a pushrod from the bottom ailerons to the top ailerons), 1 rudder, 1 elevator (with 1 pushrod that splits and goes to both elevators), 1 throttle. I'm pretty sure I'm using standard servos...You can use different receivers but they must be compatable with Futaba....just ask whoever you get your gear from....I think I'm using Hitech...sorry I can't remember but my Ultimate will be 2 years old this Christmas.....
What engine do you have or are planning to use?...I put a .75AX on mine turning a 15X6...Just an outstanding prop sound with this combo

A guy in our club has one and he uses futaba 3004 standard servos and powers it with a super tigre G90. He's only been flying for about 45 years so what would he know about anything? lol

I'm sure others will tell you to go with the digital high torque....you know, the ones that run your batteries down a lot faster.

I'd go with the 3004's personally and use a 6v receiver battery that will up the torque from 42 ozs. using a 4.8 battery to 57 ozs. using a 6v.

Thats plenty for that plane.

good luck

No, I need to save money so that's exactly the answer I'm looking for. Just want to make sure standard servos are fine. And thanks for reminding me about batteries, I forgot I need those too. Are 6v receiver batteries - will this work? http://www.all-battery.com/index.asp...ROD&ProdID=495
It says it has a hitec connector which I'm told will work with Futaba, correct?
Thanks.

This is the bipe I have
http://www3.towerhobbies.com/cgi-bin...?&I=LXDJB7&P=7

I bought a used OS Max FS-120 Surpass four stroke for $120 for it. I'll be testing it on the bench tomorrow to make sure it runs okay.

How much can I save if I can use the Hitech receiver and will it work with 2.4 GHz?

Thanks.

Unless your a great pilot doing hard manuevers and 3D stuff,the standard futaba 3004 servos should be fine if your running 2 aileron servos instead of a single like some bipes are setup for.

I will say that motor is likely going to be a bit of overkill for that plane,but will work if your careful. It might be hard to slow down if youv got a short runway like my field has and may make it want to nose over while taxing.

The only servo I would upgrade from a standard [ say 3004 ] would be the rudder. if you plan to try knife edge flight a 3004 is not man enough even on 6 volts.

So it's okay to mix and match servo types in the same plane, right? I'll order a digital servo for the rudder if so. Thanks.

I wouldn't go digital on the rudder servo. If you're going to use a high torque on the rudder I'd use this servo and save $10 over the digital.

http://www3.towerhobbies.com/cgi-bin...&I=LXDTB3&P=ML

As far as the 6v battery pack I'm not familiar with that brand you suggested.

Me, I'd use this one.....you could fly all day on it!

http://www3.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML

Man, I've got so much to learn! It never stops I didn't know there was a difference between hi torque and digital - I thought they were one in the same.

Thanks.

The standard high torque servo..... futaba S3010 $24.99
Speed: .20 sec/60° @ 4.8V and .16 sec/60° @ 6.0V
Torque: 72 oz-in @ 4.8V and 90 oz-in @ 6V

The standard high torque "digital" servo.....futaba S3152 $34.99
Speed: .22 sec/60° @ 4.8V, .18 sec/60° @ 6V
Torque: 69 oz-in @ 4.8V, 87 oz-in @ 6V

The digital servo will move the servo horn .02 of a second FASTER at 60 degrees than the non digital servo and will suck more juice from your receiver battery than the non digital servo.

For $10 less I'll wait for my non digital servo to get to 60 degrees when it feels like it rather than Pay $10 extra to get to that 60 degree point .02 hundreths of a sec. faster!

There is one other CRITICAL DIFFERENCE.

A digital servo will attempt to drive to and stay at the commanded position with full torque.

An analogue servo is less likely to maintain a commanded position under load and will be significantly slower to get there UNDER LOAD.

Some flyers will not notice the difference but many will. Digitals feel "crisper" in flight. [ Esp. on ailerons ]

yes you can mix and match servos in an airplane....I would not mix a digital servo with an analog servo though.....A servo will be more powerful and quicker on 6 volt than 4.8.....
Hitech makes a 2.4 receiver I'm sure...I think it's called an extreme or something similiar to that.....have you thought about getting that pitts style muffler instead of that flex tube you were gonna use?

No, I can't use a pitts muffler as my club frowns on them for some reason. Our field is located next to a residential area and we have a sound committee in the club due to a couple noise complaints they are out at the field with sound meters measuring sound and for some reason whenever they hear 'pitts' they whip out the meter and check. So I want to stay away from them even though I'm sure they aren't really offensive especially on a four stroke.

"How much can I save if I can use the Hitech receiver and will it work with 2.4 GHz? "

I may be wrong, but at the moment you can only use a Futaba receivers, R606FS, R607FS, R617FS with the new 2.4Ghz. systems. You can use Hitec FM receivers with Futaba FM transmitters.

At the moment, Hitec does not sell 2.4 Ghz equipment, so you cannot use a Hitec receiver with a 2.4 Ghz since they are not operating on the same frequencies.

I bet some people would tell you not to use those Tenergy batteries because of their low-price, but I've been using those exact same batteries in 2 of my planes with hundreds of flights total (for both of the planes) and they work fine.

I have heard local bad stories about the use of NiMH batteries and them not being able to handle the load of multiple servos and losing a plane. I will be getting a 6v NiCd for my extra since I am using standard servos. I know that NiCd actually offer more punch, that's why they were more popular with electric race cars than the new NiMH. NiMH is a little more user friendly because they don't have memory issues.

On servos, what do you mean by aggressive? That plane is capable of very precise flight as well as very high stress aerobatics, such as full throttle blenders and KE-snap-to-KE. Are digitals overkill? No, not if you want it to fly precisely. Disadvantage to standard servos…. May not have enough torque and precision is easily surpassed by most decent coreless analogs and digitals. Will a standard servo work in the CG Ultimate, sure. Will it hold up to everything the plane is capable of, probably not. My advice, buy the best servos you can afford in the ~60-80oz range for that plane.

NiCds do NOT have “memory” issues.

IMO, NiMH are less friendly batteries because their delta peak is softer and harder to detect, which can lead to overcharging and damage. NiMH cells also have higher internal impedance, which increases their voltage drop under load. The only real advantage to NiMH vs. NiCd are that NiMH batterys have a higher energy density per weight and they are not quite as toxic to the environment as NiCd.

Not sure what Jetmech meant about not mixing servos. Why couldn’t you mix digitals and analogs? I mix digital and analog servos on planes all the time. I.E., analog on flaps, digital on all other surfaces; or analog on throttle, digital on surfaces, etc.

Okay, from all the answers here and from Ed at my club who recommended servos with at least 50 oz-in of torque, I decided on the following.

For the throttle I'm going with a standard servo.
For the other two channels I have to buy servos for, the rudder and elevator, I'm going with hi-torque servos as the Tower web page for the Ultimate
http://www3.towerhobbies.com/cgi-bin...?&I=LXDJB7&P=7
says to use servos with at least 77 oz-in of torque - the Futaba S3305 hi-torque servos I plan on getting have 124 oz-in with the 6 volt pack I ordered.

I'm going to check with the fella I bought the plane from on what servos he has in the wing for the aileron. If they aren't hi-torque I don't think I'm going to sweat it!

You servo choice will work, but food for thought; I’d suggest getting a more precise servo, such as the Futaba S9001. Same cost, less torque (still enough at 6V), but a more precise servo. The plane will trim better and respond better to inputs. Don’t discount the need for a good servo on ailerons and the plane will hold aileron trim much better with a more precise servo.

I have these servos in my Venus and like them; they are digital and hi-torque:
http://www.horizonhobby.com/Products...ProdID=JRPS821

I am using 4.8V battery, so that should be fine for you too.

Also, you CANNOT use any brand receiver with a Futaba FASST Tx. Rx mixing only works for FM radios.

For what its worth I use 2 4.8 2300 mah batteries from all-battery. I havent had any problems with them. I actually just bought some 6v packs from there too.