jester1

Hi there,

Am new here so hi to everyone.

My first question that I hope you can help me with is regarding the new JR servo - the metal geared JR579. Spec show 8.3kg at 4.8v and 9.5kg at 6v - they are only £22.50 - which is about $40!!!

How suited would they be for, say a composite Bobcat? Or may be one of the new Flashes from Composite-ARF? I think they recommend a minimum of 8kg for servo power so these should be ok. Do I NEED to pay 3 times as much for a similar powered digital servo? Is it just the preceision of a digital servo that is better. Someone told me they hold their position better but how is that? Isn't that just the Kg rating that makes it hold its position?

Thanks for any advice

Shok

My Feedback: (28)

not sure about that one


has anyone tried the
DS821 Sport Hi-Torque Digital Servo

$29.99!!

Dave Wilshere

Jester

No!

I wouldn't use one on the main controls.

It does not have the holding power required for the sort of models you mention, the resolution is average and it's not assembled in JR's #1 factory.
Why buy an expensive model and risk it for a few hundred pounds...which any damage to model or turbine will swollow in seconds!

I have used a 579 on the nose wheel steering of my new Flash.
Other controls are all 8411, 8321 and 8231 servos

Dave Wilshere

Jack28

My Feedback: (19)

Dave , How is that new Flash?. I have one on order. What were your servo choices for the flash? Thanks Jack.

FalconWings

My Feedback: (57)

Well you know what they say about guys with large trucks? Same thing with big digital servos. I still don't get the use of 8611's on any kind of jet.
On a Rudder on a 35% Extra, sure. On a tiny aileron (even at 200mph) that moves 1/8' or less, please provide me with the wind tunnel data to justify it. Oh I'm sorry, the airframe directive indicates it my bad!

Dude forget the $120 digital, if a servo fails it fails. At least it doesn't give me any piece of mind to use any larger, more precise, current sucking digital over a good reliable analog servo. Besides my fingers and my eyes are not fast enough to tell the performance of one over the other.

Make your own clonclusion.


David

trioval00

My Feedback: (17)

For me. I use the stronger $120 digital servos. With Jets, you can't cheat yourself, because you will be the one that will loose. I use 8611's on the elevators and 8411's on rudder. I choose them more for the holding power over the strength and power to move the control surface. If you have ever had it, flutter is ugly and very costly. but then again it's your jet, if you feel comfortable with a cheap 25 dollar analog, use it... and Yes I agree, if a servo fails it fails. again this is another reason to use the stronger servos, why over work the smaller analog, when you have the stronger digital servos to choose from.
as always just my 2 cents

Mark

Ragz

I recently bought a few JR579's and have installed them in the flaps of a few jets. They havent flown yet, but I guess flaps should be ok????

amjflyer

I think the earlier point is why spend US$10000+ on a jet then save $50 on a servo, it doesnt really make sense from a 'risk' point of view. Its only another $200 or so to equip the whole aircraft with top spec servos, on many jets thats a mere 2% or so of the total cost! I wouldnt risk it, if that one cheap servo fails or in some otherway is instrumental in writing off the jet it will be something youd live to regret...(at least i would)

I cant afford to buy cheap servos...

avicom

My Feedback: (14)

I'm using Futabas 3305 in rudder and flaps in my Boomerang XL with no problem. They cost only $33.ea and proved to be good for the job. Few many guys use this one in other jets also. For the elev. and ail. controls I have stronger digital servos. If you want to try the new JR it's up to you. They have same torque than FT3305. You have here different opinions but the decission is only yours.

Rgds

roo

My grandad use to say " the cheapest thing is the dearest in the long run". Its not original I know but it still holds true. Listen to wisdom when you hear it (Dave W,s words) in this case. Cheap servos of ANY make are for 40 powered trainers etc. imho. Paul.

Doug Cronkhite

My Feedback: (34)

Never EVER go bargain hunting in the servos. These are the items that actually control your aircraft. Trying to save money here is one of the most unsafe things you can do building a jet.

lov2flyrc

My Feedback: (24)

Put me on the sticks of two identical aircraft, set up exactly the same with the exception of analog vs digital and I could easily identify the plane loaded with digi's. Cant imagine anyone not "feeling" the difference?
Some jets just dont need the digital performance but most do... No comments on the 579, havent had the chance to play with one yet.

Todd

FalconWings

My Feedback: (57)

That's cause your proabbly good Todd.

lov2flyrc

My Feedback: (24)

No! Digi's just make that much of a difference!! Try it on a sport plane your real familiar with, you will be real surprised how much you can feel....

John Redman

My Feedback: (8)

First off, as Todd stated, just about anyone can tell the difference between a digital and an analog servo. If you can't, then I guess you couldn't tell the difference between driving a Yugo or a Vette. The difference is that large.

As for using the 579 servo, do so if you choose. Using a cheaper servo on a turbine powered aicraft that pushes the 200 mph speed envelope (saying this as you mentioned two specific aircraft in your first post) is not the best decision in my book. You have a large investment on the runway preparing to takeoff, and the manufacturer has recommended a specific servo and you didn't use it, what happens when it fails? A number of manufacturers out there test their product before it is released and make recommendations for the consumer. Believe me they all want you to be successfull. Not one of them wants you to fail. They recommend servos for reasons that may not be specific to yourself or anyone else out here in the cyber world. If the cheaper servo fails, and you can't prove it chances are the blame might be laid on the design, when in fact hte servo couldn't dothe job. Now the manufacturer has lost a customer, you might walk away from jets, etc, the domino effect has begun. Heard this too many times here.

The 579 servo was not intended for any type of jet flying in its design. It was built for the average sport modeler. If you want to say that turbine modeling is for the average sport modeler we will need to define that. I would be more incline to say that turbine modeling is for the mroe professional modeler.

Use the better high quality servos, you won't be dissapointed, but if you use a cheaper one and it fails, what level of dissapointment will there be?

Don't sacrafice quality on the main actuator of the flight controls of your new bird, it just isn't worth it in any language, country, or life.

When it coems time to test fly that new jet, some people look for help and the best pilot they can find to get them airborn. I think we will all agree here. But if you figured you didn't need the best servos, then why look for the best pilot, get the newcomer to test fly for you, I am sure he will pull it off. Kinda of the same thing don't you think. No reason to skimp here.