Servos for Hawk Pro?

[JustPlaneChris]

Okay guys, I need some help. I'm (re)building a used Hawk Pro and have already purchased servos for it. I have a JR ST126MG for collective, and was planning on using JR/Spektrum DS821 for throttle, ail and elev. However, I've been reading horror stories here and elsewhere about the DS821s. I have them in my Swift also (30+ flights so far) but now I feel like I'm flying on borrowed time. :(

What would be a comparable servo that has a better reputation than the DS821, yet won't cost me an arm and a leg? :confused:

[Finless]

Chris there are 2 problems that I am aware of.
1) on larger helis (50 sized or larger) the forces involved can cause the servo output shaft to shear off. Especially if it is a servo direct to swash setup. Some people "say" this can be solved by getting a longer screw to hold the servo wheel on thus giving some extra support to the output shaft. Your swift will be fine with these trust me but to add safety put on longer screws for the wheels.

2) For nitros on top of the above it is a vibration issue as these servos are not really designed for nitro helis. The constant hammering can, as I understand it, cause wires inside the servo or the potentiometer to fail.

There you have it :)

Bob

[JustPlaneChris]

Thanks Bob! I think I'll order up some Futaba 3152's for the Hawk, and install some longer screws in the output shafts of the DS821's on the Swift just to make my stupid "little voice" feel better. :)

[Coolice]

Hey Chris,

Dont forget to look at the HiTec range of servo's as they have some good quality servo's for sensible prices.

With the 821's as Finless has mantioned I think the main problem with them is their tolerance to vibration, which on an IC machine is unavoidable.

In the UK may, including myself have suffered with failures of 811's (similar spec to 821's I think) in IC machines. Mine did however last about 1.5 years of hard 3D in a Century Falcon 46SE so I wasn't complaining to much when the aileron one packed up.

A friend is using 3 on the eCCPM controls of his Swict without problem and I think this is due to 2 reasons :

1. The flight loads are shared between 3 servo's, meaning all are less stressed and
2. Electric heli's do not have the vibration levels of their IC counterparts.

I had Futaba 3050's on my Swift and one failed, I now fly HiTec 6965's on this model and they are performing very well indeed.
.

[JustPlaneChris]

Thanks, Ian! I hadn't seen the Hitec 6965's. Those things have monstor torque AND speed! Of course, that comes at a price I see. :)

[Raptorman37]

I have DS821's in my Raptor 30 V2. i have over 50 flights on them and a hard crash that totaled another heli, and they are fine. not the fastest, or most powerful servo, but at $24 per servo the price is kinda tough to beat on a 30 machine. JR Recommends NOT using these on a 50 as the plastic gears cant take the loads, and alot of the failure reports are from people who used threadlock on the servo horn screws. The threadlocker ate at the plastic, weakening it, thus causing flight failures.

[redneckteddy103]

i have the ds821's in my nitro hawk pro .30 for about a year now . havent had any problems out of them , only problem i have is my dumb thumbs . but as stated above if your going to be upgradge the hawk to a 50 i would change them .

[theLane]

Yup... 1.5 years on my Hawk Pro with the same DS821's. 2 severe crashes and a couple minor crashes and I am still using the same DS-821's. They are awesome servo's, for the Hawk anyway.

[Raptorman37]

if you really wanna hve some fun get the new BLS451's from Futaba, .13 for 60 degrees @4.8 with 111 tq, or at 6v its .10 sec transit and 149 oz tq. $100 a piece, and they dont suck the life out of your flight pack.

[theLane]

Are the DS821's heavy on the requirements?

[Raptorman37]

heavy on requirements? what do you mean? they dont have too much power and they aren't the fastest.

[theLane]

Yup, that's what I meant. "Do they suck the electricity". I am not sure, but I think they are good on power.
Either way, they have done VERY well in my Hawk - not a single issue.

[Raptorman37]

they do use a fair bit of power, i meant they arent the strongest servo's.
hey for $29 what do want, you get what you pay for