dwilmot

Hi Danny or anyone else reading.

I am in the process of trying to select some servos for use in a TRex600N Pro and a World Models Extra 330L (60-90 size, 65"). I have a DX7 and the accompanying 4 x DS821's.

After some failures of the DS821 in certain uses, Spektrum & JR have clarified the use of the servo on their sites-

"The DS821 servo is a powerful, accurate sport digital servo recommended for RC airplane applications up to 1.20-size. For helicopters, the DS821 operates best with 30-size glow models, and up to 50-size electric. Loads and vibration in larger models may cause premature failure of the servo resulting in damage or injury to property and persons.

Important: Do not use liquid thread lock with the DS821 servo"

While I'm probably never going to load the DS821 servos enough to cause failure in the 600N anyhow, I may as well use them in the 330L (as they are more than ok for that application) and buy others for the heli. I went to the JR site and used the servo selector, looking at the "good" option as opposed to "better" and "best". For the 30-50 size heli the recommendation is for the DS821 on throttle, collective, elevator and aileron. On the 60-90 size DS821 is indicated for the throttle and collective. Assuming the Spektrum and JR servos are one in the same (someone told me that the Spektrum DS821 is the same as the JR DS589?), is this an oversight by JR in not changing the selector since the new DS821 use recommendations came out? If so perhaps the selector should be changed to prevent anyone being able to point the finger at JR if they have a failure.

Finally, what is a good (but not necessarily best) choice for JR servos for the 600N. Perhaps something equivalent to the Futaba 9252?

Cheers

David

dsnyder

That is an oversight. The 821 should not be used in 50 size nitro helis or larger, however they will work in 50 size electric helis. Some options would be the 8317 or 8717 for best performance.

dwilmot

Thanks Danny.

I think the 8317 will suffice for my flying ability, just need to find a local supplier now.

I contacted JR directly as well but have not had a reply yet. I'll leave it to you to pass on the required changes to the website.

Cheers

David

lethalivdrip

I got short changed on a Trex 600 kit that came with spectrum ds821 digital servos. I'm missing 2 double arms that were supposed to come with the 3 servos that came in the kit. Any help would be appreciated in hunting down 2 double arms with 30 mm hole spacing for those servos .

dsnyder

Contact our product support department at 877-504-0233 for assistance. Please begin a new thread if you have a question.