Hi almost finished the bobcat
A couple of questions for the guys already finished theirs
First. I noticed that the steering servo is reversed compaired to the rudder servos
Second.What gyro are most everyone using?
Third.I think this gyro is going to handle 3 servos, steering and 2 rudder servos.Can
the gyro handle this load
Fourth. If I slave the steering servo to the rudder servos that means using 2 channels,so how does the gyro then work
Thanks Rcpete

RCpete,
Yes the steering servo is mounted backwards compared to the rudder servos.

bob violett recommended the JR 450 remote gain gyro, since they don't make that anymore you can get the 460T (which I am using) and it works really well.

Yes the Gyro can handle all three servos. Just make sure they are all working correctly compared to the stick movements and the Gyro corrections.


Just use another Y cable. Y cable the rudders together and then y cable the rudders to the steering then plug the second Y cable into your receiver.

Patrick.

Hi ,then how do we reverse the steering servo
Thanks Rcpete

Pete,
I don't know which radio you are using, but if it is a JR10 channel, here's one good way to do it. I got this from Tony F.
Channel 1 Throttle
Channel 2 Right aileron
Channel 3 Right elevator
Channel 4 Rudders (Y harness)
Channel 5 Retracts
Channel 6 Left Aileron
Channel 7 Left elevator
Channel 8 Brakes
Channel 9 Nosewheel servo
Channel 10 Gyro gain
Use the JR mixing programs (51 through 58) to create mixers tying the elevators together, and to mix the nosewheel to the rudders. Reverse the servos as required in code 11 to get the proper throw direction.
You can even mix down elevator to aux 3 to have the brakes work with down elevator application when the gear is down, and still use aux 3 as a parking brake.
See Tony Frackowiak's great BobCat trimming article on the BVM Jets website. You'll find it very helpful, as he knows more about trimming than most people do. His BobCat is the best flying one around. www.bvmjets.com
I'm using a JR G450, but the new 455 is the replacement. I had the 450 working the rudders and the nosewheel, but now I'm using Tony's setup, and the gyro is unneccessary on the nosewheel. I flew mine for 49 flights before switching to Tony's trimming methods. It flew great, and I'll report back when I get more time on the new set-up.


Harley Condra
BVM REP
RAM REP
Buy American!!!!!!

Hi, yes I hae a 10x and thanks for the info.
Thanks Rcpete

Harley,
Your instructions make sense but I think having the nosewheel connected to the gyro helps a little in ground handling during take off.

Patrick,

The Bobcat tracks so well it does not need the gyro on the nose wheel. The other thing to consider is that you should be setting it up where the gyro has more gain with the gear down. This might be too much gain for the nosewheel. If you set the gyro up for the nosewheel then you might not have enough gain for the gear in the down position in the air.

David Reid

David,
You make a good point. I think I will have to rethink my installation. I have not noticed any steering problems with mine after 4 flights but I don't have my gyro dialed in all the way yet. So I think I will take the gyro off the nosewheel and see how she tracks without it, but with it, she is as straight as an arrow.

Patrick.

p.s. The new bobcat is flying like a dream. I will have to post some pics.

Patrick,
You can adjust the centering of the nosewheel independent of the rudders, by using the aux 4 channel. You can also reverse the servo as/if required too.
Use code 15 to set the center, or just turn the aux 4 knob as required to find center. Once the servo has been adjusted to track straight down the runway, only a crosswind will affect the take-off roll. Only a minor correction is required. Once you get the set-up dialed in, you won't have any problems.
David is correct!
Harley Condra
BVM REP
RAM REP
Buy American!!!!!!

Harley,
thanks for the explanation of how to do it, I really did appreciate it, but I fly Futaba and what you wrote is kind of greek to me. I have already made the adjustments to separate the nosewheel from the rudders and set the center where it was before. Unfortunately I will not be able to test it tomorrow as I have a bent strut and was sent the wrong one to replace it. It will have to wait until next week to get tested.

Patrick.

Patrick,
Sorry about the Greek.
Regardless of the radio brand, you won't have any trouble without the gyro on the nosewheel.
Harley Condra

Hi Guys, Just a little tip. For those that do not have a reversed servo, I took a short piece of yellow nyrod and cable, moved the hole for the pushrod over a little and just put the servo arm on the other side. Works like a champ. The nose steering is very positive and works just as well as the wire rod. Bill Harris

Just another thought. I just finished wiring up my F-15, using a JR Matchbox, rather than the Y-connector on the nosegear/rudders.

Really works neat since you can individually reverse a servo, adjust ATV, and set center, all with the Matchbox, which is very tiny. Any gyro command goes out to both servos, or an individual servo, depending on whether you hook the gyro upstream or downstream of the Matchbox.

I now have just one lead coming out of the Matchbox going to the rudder channel on the 950S, and two leads coming into it, one from the nosegear servo and one from the rudder servos which are Y'd together, although you can control up to 4 servos on one channel, so you could hook up each rudder servo individually on a twin rudder airplane. I now use only one channel and no mixes.

It has a very fine adjustment capability (it adjusts in 1 msec pulse width increments) so you can easily dial in exact centering and travel.
It also gives you the option of hooking in a separate battery supply to those servos controlled by the matchbox, thereby taking the load off the receiver/battery. Not as important in jets as in giant scale where one of my planes has 4-8411's on the rudder and 4 on the split-elevator

Tom

Good reply Tom, that has always been the worst part of rigging for me....trying to get the mixes just right. I forgot about the new matchbox and the Bobcat has several Y cable connections. A few may be eliminated by the matchbox...........