I'm finishing my BobCat XL and planned to install Airtronix 94141 servos on the elevators. When I powered them up, I was not happy with the holding power, but understand the servos work fine in this application (per Frank T. - any thoughts, Frank?). I've been advised by a trusted friend to install JR 3421 or JR 8417 instead. BVM plans show JR 3301 which are out of production (replacment is JR 3321). Problem: which ones are best for this particular applicaton? 8417's are digital, and have the same physical size as the 8411's but don't have the same torque (also big and heavy for the tail surfaces). 3421's are digital, small (fit into the servo cavity's) but are down on torque (65 oz) and seem to have a reliability problem (as related by others on this forum with rudder/gyro use).

Any thoughts/suggestions/recommendations are appreciated.

Thanks in advance,

Les

Do NOT install the 3421's on the elevators. BV calls for the 3301 which is the digital replacement for the 3321's and they work very well. Problem is that space is limited in the horizontal stab. For the rudders install 9411's, in lieu of the recommended 3421's. I don't know anything about the airtronics servos but I have close to 100 flights on my XL with a P-120 and have had zero problems with the 3301's on the elevators.


David Reid

Sir, JR DS3301 servos are the recommended type. JR 3321 servos have been phased out and replaced by an updated digital version ie 3301. Hope this helps! WHMC

Any particular reason why ?

If I recall correctly, TonyF is running 3421's on his elevators quite happily.

I know you and I have both had problems with the 3421's on rudders, but I'm not aware of the 3421's having problems in a situation where there is no gyro involved. So, why ban them from the elevator too, rather than just the rudders ?

Regs,
Gordon

Gordon,

We have had 4 of them fail. Of the four that failed 3 of them failed on the ground without much gyro activity. It is my opinion.....and my opinion only that they are not a good servo. Besides the 3301 is a wing mount servo and the mounts in the Bobcat stab are setup for this style. For all I know it may be the same guts in both servos but I have yet to hear of a 3301 failing.

My opinion.

David Reid

I've got 370 flights now on the BobCat with 3421's on both the rudders and elevators. However, with what we have seen, I would not recommend using them on the rudders now. I don't plan to change mine, but if I built a new BC I would install 9411's on the rudders. My next BC may very well have a single 8411 on the elevator, just to make it simpler. It's also a bit more precise servo.

Another point, my BC is a standard with a 500, so it may not be seeing the loads of the 120/1000/180 powered BC's out there. Must be some reason why my 3421's just keep ticking.

Originally posted by TonyF
My next BC may very well have a single 8411 on the elevator, just to make it simpler. It's also a bit more precise servo.


So are you planning on making a small fairing to accomodate the servo's extra size ?

Gordon

That's what I would do!

In my Bobcat XL with Ram 1000 set at 22lbs. I've got over 30 flights with two 4721 (tried, true, reliable). Yes, they're a tight fit, but I've yet to have any problems with these coreless analog servos. Being tail heavy wasn't an issue, I just planned accordingly by shifting all on board equipment forward during the construction phase.

Jake Bruckler

Guys, thanks for the information, but one question keeps coming up - some of you are indicating the 3301's are still available and should be used. My supplier says they have been discontinued and are not available (which is why I looked at the ATX 94141 in the first place), so who would know for sure? I'd rather use the 3301's if they're still available, but have other options if they're not. I could shoehorn a larger servo into the stab cavity, but would rather stay with something smaller and digital, if possible.

Thanks again for the input.

Les

Les,

JR DS3301 are in stock at Horizon Hobby.

Go Here:
http://www.horizonhobby.com/products...&pc=JRPSDS3301

Todd

OK guys, 3301's it is!!! Thanks for all the info and sources. I've got two of them on order for the elevator. They should arrive next week - by then I should have everything else installed and waiting on the servos to finish the bird up.

First flight soon after!!!

Thanks for all the input and advice.

Regards, Les