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Compass Knight 50 > jr 821's for knight
 
 
whatwasithinkin
Heliman
Location: Ponca City OK

Are JR 821 servos enough for the Knight 50? If not what would you suggest for a good budget minded servo?
02-09-2007 Over year old.
 
 
houstonrevo
Senior Heliman
Location: Houston, TX

I used 821 before and have them fail on me on ccpm. I still have one on throttle but I wouldn't dare using them on cyclic again.

Dave at the kyosho forum have good luck with the older version DS811 for 50 size CCPM.

I know Chirs @ RCHELIWORKS.NET still have them in stock. I just got done talking to him. I will use them before the 821.

There are also several post talking about 821 failure here at RR. Just do a search and you will find them.
02-09-2007 Over year old.
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

I'm running DS 8231's on my Knight, seem to work quite well.
A mate of mine had some 8417's on his Knight which gave it rather rapid collective and cyclic response!

Am I still in control?......................OH!
02-09-2007 Over year old.
 
 
beavis1
Veteran
Location: New York state

also had a 821 fail

I also had a 821 fail on me. It was on just the third flight so it sure did not wear itself out !

If you are going to 3D tic toc ect I would think about it.

I lost all faith in them myself.

Holo foil power !!! Magnum fuel Century Rep
02-10-2007 Over year old.
HOMEPAGE  
 
 
whatwasithinkin
Heliman
Location: Ponca City OK

I had one fail on about the 6th flight on my JR Venture 50. I thought I had a radio issue until I tried to use the servo again and saw that it was completely dead. I was in hopes this was just a strange luck ordeal but it looks like there are many out there with the same ds821 issues. Thanks for the input guys. I'm going to get some futaba 9451's what do you think of them?
02-10-2007 Over year old.
 
 
raptor50luvver
Veteran
Location: southampton UK

I have seen 2 output shafts fail on 821`s just by pulling the servo horn off,,they are very brittle

I WOULD NOT use an 821 on anything other than throttle or rudder on a plane im afraid
02-10-2007 Over year old.
 
 
eric_b
Key Veteran
Location: Denver, CO, USA

I wouldn't use the 821's on anything, given the failure reports that I've read.

However, I'm using 811's on my Knight, and they work very well.
02-10-2007 Over year old.
HOMEPAGE  
 
 
houstonrevo
Senior Heliman
Location: Houston, TX

I am usually fairly happy with JR product and customer service. However, with this whole JR ordeal, it was the exception. When I told them about my 821 failure and the multiple failures that I've seen at RR, they told me that they have never heard of it and they are using 821 to fly heli and never have any problems reported.

I am sure they hang out at RR and are aware of the problem. I would be happy that they shipped me some old 811 to replace my 821 for warranty. But they keep sending the 821 back. At least if it fails on throttle, I can still auto and land.
02-10-2007 Over year old.
 
 
whatwasithinkin
Heliman
Location: Ponca City OK

what if it fails wide open in the throttle position. You couldn't autodown then could you?
02-10-2007 Over year old.
 
 
houstonrevo
Senior Heliman
Location: Houston, TX

No, but at least I still have power, just have to be easier on the collective to land...hopefully!

May be I should get another servo too:-)

I have 3 ds821 sitting around...I pay $retail for them and now I have to look for another servo:-(
02-10-2007 Over year old.
 
 
raptor50luvver
Veteran
Location: southampton UK

thats my thinking,on throttle if the output arm snaps the engine will probably vibrate barrel to full throttle but if this happened to me i would just keep engine loaded until tank was empty then auto down
02-10-2007 Over year old.
 
 
ez2bgman
Elite Veteran
Location: N'awlins, LA

2 weekends ago the output shaft on an 821 broke while trying to remove the servo horn on one of our club member's R50. I would never use these cr@ppy a$$ servos in any of my helis. The 811's are much better. I would use Futaba 3151's before putting an 821 anywhere near my heli.

Gary
RJX of USA
Magnum Fuels
SwitchGlo
>Hot Girlz in da gallery<
02-10-2007 Over year old.
HOMEPAGE  
 
 
eric_b
Key Veteran
Location: Denver, CO, USA

Quote 
what if it fails wide open in the throttle position. You couldn't autodown then could you?

Why would you put questionable equipment on your helicopter? If you think something could fail, then it shouldn't be put in the air.
02-10-2007 Over year old.
HOMEPAGE  
 
 
whatwasithinkin
Heliman
Location: Ponca City OK

I bought 9451's for my Knight today. The guy at the hobby shop said he was flying them in some 50's with no problem but I'm not about to rebuild another heli over a cheap servo. I don't like the idea of spending 80 bucks a piece for servos but crashed heli parts get expensive quick. Its a shame too it seems like it would be just the ticket but I say fly at your own risk. What really sucks is when my heli crashed it was headed for the pits at one point. Someone could have been seriously injured.
02-11-2007 Over year old.
 
 
raptor50luvver
Veteran
Location: southampton UK

eric

Because i trust them on a no real load application like throttle but not on a load application like cyclic..

Im saying the output shafts can be a bit weak,i dont doubt their integrity otherwise,the ones i have on throttle are working fine
02-11-2007 Over year old.
 
 
whatwasithinkin
Heliman
Location: Ponca City OK

The 821 that failed on my Venture simply just quit working bad pot most likely. It was just overworked I assume. The output shaft was not the issue. I think they are just not built with top of the line components like a more expensive servo. All I know is I'm ticked my heli is trash.
02-11-2007 Over year old.
 
 
beavis1
Veteran
Location: New York state

Amp Board

My return stated it was the amp board on the servo that failed.

They had little concern over my heli damage due to thier servo failing. The 811 servo for years has had a good rep. This servo has better specs and you would assume it was better but the number of reported problems speaks for itself.

Holo foil power !!! Magnum fuel Century Rep
02-12-2007 Over year old.
HOMEPAGE  
 
 
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Compass Knight 50 > jr 821's for knight
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