I had alot of fun taxiing my jet around the driveway yesterday

It did bring up a few questions:

1) My steering settings currently alow me to turn the plane withing a very tight radius, Probably 10 feet or so. I would imagine this would be overkill on a takeoff run or rollout.

2) I have the steering servo slowed. Im assuming this will help with the fluidity of the steering process at high speed and may reduce tire wear.

3) I don't think my nosewheel should be operating while retracted during rudder input.

What do you think?

Thanks! Pete

I'm concerned about using servo slow for and directional control. I suspect this will make your takeoffs harder. Here is what works for me (all learned here on this forum)

- I use a different channel on the same rudder stick such as the steering is completely different from the rudder
- I use 80% of expo on the steering and about 30 degrees each side
- If the plane is still unstable during the takeoff roll, I use a cheap gyro with about 50% gain. That works very well
- Optionally, setup a mix to disable the steering once the gear is retracted. You can also force the steering to be straight before the retraction occurs.
- One last other optional great thing is to setup a mix to give as much throw as available when full left or full right is given. So the throw is still exponential with about 30 degree each way but once the stick reaches its maximum position, all the available throw is used in one big step. This is great for tight maneuvers and doesn't cause any problem during takeoffs and landings.

Arnaud

My opinion-
10ft diameter circle is tight but it will suit some models, in general the jets do like a more responsive steering than prop planes. They get no benefit from rudder steering in the prop wash and the noswheel can easily get light or have little contact with the ground as it bounces while speed picks up, so powerful nose steering is important. If you want to get fancy, apply dual rates or expo to the steering servo switched by the high and low throttle setting.

Servo slow is not a good idea, it will delay the response to your input making you apply even more steering than is needed, which the servo will eventually catch up with and over steer, so you back off but the servo delays it and........ so on and on. You need rapid response during the take off run.

I program my radio to switch off the steering servo when I select wheels up but apart from saving a few mAh of battery capacity I am not sure if it really does anything useful!
Harry

Pete -
set up the servo with standard speed and LOTS of expo on the nose wheel, that way,
it will be very smooth on takeoff and landings, and you can still turn tight and fast when
taxing and if the need arises!

Tor

I use dual rates, one for taxi (hi) and one for take off (low). I leave the low rate on all flight since i rarely use rudder in flight. I'll kick on high rate when taxiing back to pits if needed for turns. Doug

Thanks for the ideas guys. Im sure I'll be able to work something out now!

Pete

I use dual rates, 100% for taxi out and turn into the wind. Click to low rate, typically 25-30% travel and away we go.
V..

If you have a JR radio, at least in mine, the dual rate for rudder,
has 3 positions, so I adjusted it for 3 types of steering. High, mid, and low
for take-off.

Hector

Pete - if you're steering is pull-pull like many are, the cables go slack when nose wheel is retracted, and thus you don't have to worry about the nose wheel turning
while flying.

Bob

I used to do alot of fancy dual rate stuff on my jets, but I found that adding a gyro really helps on take off and landing. It reduces the work load on both landing and take off.

The gyro only works on the steering servo, there is no mixing to turn anything off and if I forget to hit the dual rate switch, the consequences are minimized.

And it doesn't matter if the steering servo is moving with the gear up. Try it on the ground and you will see.

Anything to help with my mental workload, I'll take!!

Raf

Pete, you have a lot of answers here, but here's the one that works the best and was stated above.

Two things you can do to assure very stright problem free take off:

1) put a $50.00 gyro on the nose wheel steering servo. (all of my jets have this).
2) put the expo on nose wheel steering to 70% or more

The increased expo allows you to use all of the travel of the servo if it is necessary, yet softens the middle so much that you can steer very accurately. If you put rates on a switch and you are in a tough crosswind, and you need more steering, you will be totally screwed. I have done that before I learned the above, and damaged an airplane badly. I have roughly 1500 flights as per the above two recommendations and have never had a botched takeoff due to steering.

I set up a separate servo for the nosewheel, and make one of the rotary knobs on the 14mz the primary control for the nosewheel servo.

Then set up two PMIXes from rudder to nosewheel, one is on all the time, and maybe 30-40% travel, the other one turns on below 1/3 throttle and is 60-70% travel.

Now you have full nosewheel authority for tight turns while taxiing, and much less twitchiness while taking off. And the knob provides a nice way to rapidly adjust center on the nosewheel. On this TX you can push in the rotary knobs so they don't protrude and get bumped if you want to.

The "lots of expo" idea also sounds very good, and has the advantage of extreme simplicity :-)

I don't worry about disabling the nosewheel servo in flight because of the slack cables, as mentioned above, though it would be quite simple to set up...

Dave

Dave ,

Great idea , but what about the roll out after landing ? Might be a little sensitive . Maybe another mix to speedbrakes or landing flap ? Logic on the 14MZ could be put to good use !

Marc

Hey, that's interesting, I never thought about that Marc! You are absolutely right about the principle .. but I can say it does not seem to be a problem in practice (but my jets all land pretty slow... R54 and F15), and yes, it would be perfect for use of logic to set the sensitivity down with the flaps or the crow...

thanks for the thought...

Dave

Well, Marc, very good thinking ... I've not had the problem you mentioned with my warbirds (who stay with the tail flying till they are very slow) or with my R54 jet (very wide main gear) .. but .. my Yellow F-15 is a bit touchy on the ground, even with very low rates ... due to the very narrow track of the main gear. And, Ihad just the problem you described with twitchy steering on a landing rollout .. so Iput in a logic mix as you suggested. Took all of 5 mins at the field.

Simple: two mixes from rudder to nosewheel (separate servo for nose steering, of course). One mix ison all the time, mixes a very small percentage(about 20% is good) from rudder to nosewheel. Good for high speed such as T/O and landing rollout. Second mix, on when throttle below 25% AND flaps are up. This is for taxiing, adds another 60-70% mix to the first.

So, when landing, rollout at high speed is with minimal travel, at end of rollout, raise flaps, now have full steering for taxi. When taking off, minimal throw to soften steering for takeoff.

I just KNEW those logic mixes would come in handy :-) Thanks for the suggestion.

Dave

hey pete i was using 30 to 40 expo on all my jets but have gone to 10% with about 50-60 rate take off i felt like the expo was making me a little late on corrections ,i have never tried a gyro but alot of guysusethem,i think the thing that gets me into trouble the most is letting slop get in the steering just my 2cents

plug your nosewheel servo into the rudder port on your receiver and mix the rudder to it if you have an extra channel. You can use the dual rate rudder switch then if you wantand not affect the rudder. It makes trim on your steering easy also as it's now on your rudder trim. I read this in a Jim Hiller article once and it works great.</p>