arw9fmw

My Feedback: (4)

I really hate to start this thread again. I have **60** pages printed from the other threads on the subject. When I read through all of them I become more confused. (I confuse easily) This concerns the rudder servos (JR3421 & JR9411) and JR gyros (450 and 460T). It seems the general concensus concerning the servos was if you were going to change them put in the JR 9411 (which I have done). I think BVM recommended this change. Seems like the two gyros in question were the JR 450 & JR460T. At the time people were switching back to the JR 450. I had a hobby dealer try and find a JR450 gyro. He could not find any in the US or overseas. So what is being used besides the 450? If it is the JR 460T how are people handling the change in centering when switching from low to high gain. I know there will be different methods of wiring the rudder servos, gyro and nose wheel steering servo. What are most people doing?

Forgive me bringing this up again. I hope there will be a general agreement on the subject.

Harley Condra

My Feedback: (4)

Many pages have been devoted to this subject. Some have contributed their ideas, while others have contributed their experiences with the BobCat and the various servo and gyro choices.
Speaking from my own experience, ( 94 flights on my BobCat XL, powered with a RAM 1000R), I have had my share of rudder servo problems.
I cured the melted DS3421 with a pair of DS9411's on the rudders, and put another pair on the elevators. The 3421's will be used for other applications, specifically non-gyro applications.

JR now recommends the 3421 to be resricted to non-gyro useage.
BV did recommend the installation of the DS9411's recently, and I would heed his advice. I feel that he's on the money again. Some folks, such as Tony Frackowiak, have flown many flights (300+) with the DS3421's without any trouble. Who knows why? Tony is the Master of the control set-up, so I would expect him to have logged more flights than most without problems. I hope he gets another 300+ without trouble.

Mine went away during post flight taxi back to the pits, after about 40 flights (I think). In-flight failures such as I experienced (on the ground) are usually airplane killers. I was lucky. I figured that my luck was used up, so I switched.

I'm using the 450 gyro, as the 460 was not released when I started flying my XL. I have no problems with centering, and do not use dual rates on any of the surfaces.
There is no difference in centering going from low to high gain in mine. I was not aware that the 460 had this problem, and frankly would not expect it to.
I know of several 460's out there in BobCats, and none have had any problems that I am aware of. I would not recommend any other gyros, as I am not experienced with any other than JR.
Futaba has a good reputation; do they have a good airplane gyro?

I am using all ten channels, and here is how it is mapped out:

1. THROTTLE
2. RIGHT AILERON
3. RIGHT ELEVATOR
4. RUDDERS (Y)
5. RETRACTS
6. LEFT AIERON
7. LEFT ELEVATOR
8. BRAKES
9. NOSEWHEEL
10. GYRO GAIN

A neat part of this set-up, is that the nosewheel can be centered electrically, while taxi-testing. You don't need to adjust the linkage. You can also "sub-trim" all of the surfaces independantly, except the rudders.
A flight mode adds a small amount of "down elevator" when the gear goes down. It is trimmable when in the flight mode, independant of the gear up elevator trim.

The gyro gain can be easily changed as well.

This is just one way of doing it, and I must admit that this program and set-up was developed by Tony Frackowiak, and loaded into my airplane, and trimmed out by him one windy afternoon in his garage.

You can read about his set-up in the BVM website.

Duplicate it, and you will have a groovy flying airplane.

Harley Condra
BVM REP
RAM REP
AMA 2045 Leader Member, CD......

Doug Cronkhite

My Feedback: (34)

One thing I'd like to add to this..

NONE of the gyros out there tolerate low voltage very well, so it's very important you ensure you have no binding in your setups. If a servo binds or stalls, your current draw goes way up, which lowers the voltage. The effects of low voltage are unpredictable at best.

The only time I've ever had a gyro change neutral on me was when I didn't give it time to stabilize following power-on of the radio system. You should leave the aircraft stationary for at least 3-5 seconds after turning on the radio before you move anything.

Doug Cronkhite
Team JR

DavidR

My Feedback: (1)

I have had a few problems with both the servos (3421's) and the gyros. I had a 450 gyro go south on me in the air. I noticed the airplane rolling to the right and when I dropped the gear it did it more severely, and the airplane yawed to the right. Upon landing I discovered the rudders kicked 3/4" to the right. I changed to a 460T gyro and did a few simple tests on it. Leave the airplane turned on for 20 minutes on the bench, notice if there is any change. There was none. Next I heated the gyro gently with a hair dryer, there was no shift with temperature. I put around 20 flights on the airplane at Winamac and it went south as well. I had the good fortune up there to have John Adams (R&D man at Horizon) at the event so he and I put the airplane through the same tests there. Let it sit in the shade for 20 minutes, and then out in the sun with the canopy on. Airplane tested ok, so I flew again, on final approach the ariplane was rolling slightly but was yawing to the right. After landing I found the rudders deflected again. I replaced the gyro with another 460T and have about 30 flights on it now with no problems. I also altered my setup slightly, I have about 10% gyro gain with the ger up, and 55% with the gear down. The gyro gain is on the aux 5 knob on my 10X and I can turn the gain all the way off. I changed to the 9411 servos about 50 flights ago and they work fine.


David Reid

jbsmith

My Feedback: (1)

Hey Fellas.

I too am in the same boat. I'm seriously considdering using a Futaba GY 501 out of my heli. It has been working great with the JR reciever and Fut. servo for about a year.
It is just my feeling that the Futaba gyros are superior to JR's.
I have seen few heli pilots flying JR gyros, but I have seen several flying JR with Futaba gyros.
I'm not bashing I'm just offering my opinion and my experiences.
Anyone out there using Futaba gyros with JR in jets???


Thanks
Jeremy

DavidR

My Feedback: (1)

It is not that the gyros quit working it is that they have a shift in centering. In a helicopter this can be masked by the fact that when the gyro shifts it makes the tail rotor shift as well, this in turn causes the gyro too react and cancel the inpput out by trying to maintain the tail in the same position. So it is not as noticeable in a helicopter.

DR