Guys,

Forgive me I am still learning!

Right,

The model I'm building a BVM T-33 with Super Bandit landing gear has two servos linked by a JR Matchbox to control rudder and Nosewheel.

When take off finally happens and the gear is raised, the BVM nosegear steering arm ( fork like assembly that latches onto the oleo) automatically releases from what I see, thus the nose geer cannot be steered whilst retracting into the well. I am assuming that once flying both servos (rudder and nosewheel) will still move, but as the mechanical mechanism has released, the servo has no effective load.

The gyro has been reccomended for ground running as the T-33 has a narrow track, so I guess a mix to the gyro most useful to either turn it off once the wheel retracts or reduce the gain, so that whilst airborned the rudder is only controlled by the pilot (allegedly!). When I am ready to test, I will need some advice of how to set that up with a JR PCM 10X!

However,

Hypothetically if taking a cross wind landing, loads of larger rudder movements etc , and then hit the gear switch, it is possible for the nosegear to come down, and the fork to miss the relatching on the oleo preventing turning and possibly worse, forcing a particular turn.

Like I say I am learning so I am not sure if this actually possible to do and I am worrying about something uneccesarily, or if it can happen, what can you do to reduce the risks?

As I said before the really dumb question is the one not asked, so I don't mind asking some questions that are stupid!!

Gazzer

G'day Gaz,

I know that some people use a mix to ensure that they only drive the NG steering servo once the gear has been selected as "gear down". I guess that in theory it would seem that this approach fails to take account of the fact that the mix comes into effect immediately gear-down is selected, while the gear itself takes a greater amount of time to extend, but in practice it seems to work well enough.

Personally I don't use any such mixing, and that works fine for me. YMMV, of course.

Gordon

Yea, the KingCat has the same type of system. We noticed this as a problem when we set our failsafe to full right rudder and gear down (a safety requirement for flying these planes that belong to NASA - I don't have my planes setup that way). When we tested the failsafe, the rudder would go to full deflection while the gear was in transit, and the nose gear steering would disconnect as you have seen. Then when you tried to retract the gear a second time, the nose gear would get turned 90 degrees and you'd have a real mess. We fixed this by changing the failsafe to rudder straight, but right aileron to give us the required spiral on failsafe.

The point of the above paragraph is that you can in fact make the situation you noticed happen if you try. However, that being said, we run gyros on the nose gear of the KingCats too, and we have NEVER had a problem with the nose gear steering becoming disengaged in normal flying. Remember, most jet guys drop the gear on low-speed a downwind pass that is either followed by an official "gear pass" upwind to verify that the gear is down, or the real upwind landing approach. During the downwind pass where the gear cycles, you're typically not using the rudder and the gyro's authority, coupled with the plane's normal stability, means that the gyro-induced rudder movements are small enough that the steering yoke will engage OK.

We also have a BVM T-33 set up this way and it works fine too. Set it up as per the BVM directions and go fly it. You'll be OK

Also, BV does not turn off the gyro on his airplanes in flight, but leaves it on. In flight, the gyro reduces the wag of the tail and the resulting dutch roll noticably - especially when its windy. The gyro makes the plane track much straighter in those conditions and thus makes it fly more realistically. A trick that many scale guys use...

Gotcha guys,

Many thanks.

So downwind hands off the left stick in my case!!!!!

And just after take off too!!!

RH,

What Gyro do you use in your T-33 and out of interest what engine have you got in there?

Thanks,

Gazzer

The T-33 belongs to the NASA group too. They use JR gyros in all of their stuff. I think that one is a 500T, or it might be a 410T. They've got an AMT 180 engine in there. Its airstart, but they have a big trailer to haul around all the stuff it takes to start it. Its a nice little engine and the spoolup time is very quick. That airplane is one of my favorite of the NASA planes to fly - although it does take practice to land well...

Bob