Nose wheel steering

Operating an F-16 on the ground or in the air - from the engine start sequence, over replacing a wing, to aerial refueling procedures
  • Author
  • Message
Offline

jeroen

Enthusiast

Enthusiast

  • Posts: 24
  • Joined: 09 Jun 2004, 18:41
  • Location: The Netherlands

Unread post09 Sep 2004, 14:31

When a F-16 takes off, the pilots deselects the nose wheel steering when the airspeed is 70 knots. After landing, he reengages them at 80 knots. I wonder how this is done? I have looked around in the viper's office and all I found was the missile step swich which controls front and rear cockpit nose wheel steering command. Is this the switch that engages the nose wheel steering, even in a single?

How does the pilot steer the aircraft on the ground? Does he use the side stick controller or the rudder pedals? If he uses his feet to changes direction, there seems to be no need to engage the nose wheel because the rudder will always move in the right direction... If the SSC does the job, what is the fonction of the rudder pedals?

I hope that anyone can answer my questions

Jeroen
Offline

FlightTestJim

Active Member

Active Member

  • Posts: 157
  • Joined: 05 Apr 2004, 19:29
  • Location: NH

Unread post09 Sep 2004, 15:24

Nose wheel steering is engaged, and disengaged using a momentary push-button switch on the side-stick controller (upper right side). By the way, it?s the exact same switch used inflight to disconnect the boom during air refueling.

The F-16, like most other small aircraft, steer on the ground using the rudder pedals to move the nose wheel (the rudder will also move). The rudder only becomes effective when there?s enough air going over it (aka airspeed). On the ground, the nose wheel is the only way to steer (unless it's really icy, and you can drag the nose wheel sideways).

Larger aircraft (747s, C-130s, KC-135s, etc) use the rudder pedals for small deflections of the nose wheel side to side, but use a large ?tiller wheel? on the pilot?s left side, near his knee, to steer the nose wheel beyond certain limits.

The F-16 side-stick controller only takes care of pitch and roll of the aircraft. The rudder and nose-wheel steering control yaw movements.
Offline

FlightTestJim

Active Member

Active Member

  • Posts: 157
  • Joined: 05 Apr 2004, 19:29
  • Location: NH

Unread post09 Sep 2004, 15:44

Here's a photo of the side-stick controller, though the nose-wheel steering switch isn't quite visible. It would be used by the pilot's index finger, on the outboard, upper most corner of the stick.
Attachments
NWS Switch location.JPG
Offline

Gus

Enthusiast

Enthusiast

  • Posts: 98
  • Joined: 18 Aug 2004, 03:38

Unread post09 Sep 2004, 21:17

As an aside, the button also has a missile step function which allows the pilot to select another like missile on another station. For example, I have AIM-120s on stations 1, 2, 8, and 9. The missile on sta 9 has failed, and I can hit the button to step the SMS to select another AMRAAM on a different station...sorry for the digression.

Gus
Offline

Grunt

Enthusiast

Enthusiast

  • Posts: 53
  • Joined: 08 Sep 2003, 21:00

Unread post09 Sep 2004, 21:56

Gus wrote:As an aside, the button also has a missile step function which allows the pilot to select another like missile on another station. For example, I have AIM-120s on stations 1, 2, 8, and 9. The missile on sta 9 has failed, and I can hit the button to step the SMS to select another AMRAAM on a different station...sorry for the digression.


So how's that button know which function it's supposed to do?

In the book Modern Military Aircraft F-15 Eagle, it shows a diagram of the F-15's joystick and all its button's functions. By the pilot's pinky finger there's a paddle switch called "Autopilot/nose steering release switch." Does this mean the pilot can steer on the ground with just the stick?
LET'S ROLL!
SPIRIT OF 9-11-01
Offline

FlightTestJim

Active Member

Active Member

  • Posts: 157
  • Joined: 05 Apr 2004, 19:29
  • Location: NH

Unread post09 Sep 2004, 22:40

The aircraft knows what function to perform, based on the aircraft?s actual flight condition. On the ground, there's no need for air refueling, or missile stepping, so with weight-on-wheels (WOW), the switch activates or disengages the nose wheel steering (NWS) system. Inflight, with the air refueling door open, the same switch will operate as the ?air refueling disconnect switch? and kick the air refueling boom out of the receptacle when depressed. Inflight, with the air refueling door closed, and missiles selected, it will step through each missile.

I don?t know much about the F-15, but on the FB-111, the pinky paddle switch on the stick, is the ?auto-pilot override.? You can?t steer the nose wheel with the stick at all, but can disengage the auto-pilot and NWS with that switch.
Offline

Gus

Enthusiast

Enthusiast

  • Posts: 98
  • Joined: 18 Aug 2004, 03:38

Unread post09 Sep 2004, 22:54

For the NWS, there is a weight on wheels (WOW) switch. If the gear is down, and the WOW switch is activated, the button activates the NWS. If the AR door is open and no WOW, the button becomes the AR disconnect, and absent of those, with a air-air weapons mode called up, it will step the missiles.

If the WOW switch fails, the NWS light (green and on the right side of the HUD) will alternately be on as the button is depressed, and the AR rdy light (blue) will not illuminate.

Normally, the AR rdy light illuminates when the AR door is open and the receptacle is ready for the boom. After disconnecting the boom, the AR disconnect light (orange) illuminates momenatrily, then the AR rdy light comes on.

This certainly could be a thread on its own...multi-functions of switches on the throttle and stick. As jets can do more, there are only so many places to put buttons and switches on the throttle and stick. Since HOTAS is the way to go, the designers have to make them multi-functional to do all that's required. The manual range/uncage knob on the throttle is another good example.

As for the F15, they steer on the ground just like most fighters and trainers. With the rudder pedals. On the T37/T38, the NWS buton was on the stick and had to be held continuously for NWS. The F-16 has the button which push it once and it's on, push it again and it's off. Much nicer!! Having not flown the F15, I can't speak to how that system works, but by the sounds of it, the paddle switch may have to be continuously depressed to enagage the NWS.

Bottom line: Using NWS is like steering a sled with your feet.

Gus
Offline

Gus

Enthusiast

Enthusiast

  • Posts: 98
  • Joined: 18 Aug 2004, 03:38

Unread post09 Sep 2004, 22:55

Sorry FTJ!

Stepped on your transmission!

Gus
Offline

Grunt

Enthusiast

Enthusiast

  • Posts: 53
  • Joined: 08 Sep 2003, 21:00

Unread post10 Sep 2004, 01:45

Thanks Guys :D
LET'S ROLL!
SPIRIT OF 9-11-01
Offline

IDCrewDawg

Forum Veteran

Forum Veteran

  • Posts: 857
  • Joined: 22 Apr 2004, 16:54
  • Location: Florida

Unread post10 Sep 2004, 04:29

The WOW switch that activates the NWS (nose wheel steering) is located on the back side of the nose shock strut. When the shock strut is fully extended the NWS is disengaged. So if the airplane is very light because of fuel load and configuration, the F-16 can be on the ground and the NWS not work due to a fully extended shock strut. Pilots will know this is the case if the NWS seems to be intermitent during taxi.
Offline

STBYGAIN

Active Member

Active Member

  • Posts: 188
  • Joined: 13 Jun 2003, 03:46
  • Location: RJSM -- Japan

Unread post10 Sep 2004, 23:12

After landing, he reengages them at 80 knots.


That would be a little dicey. That's a fast way to go off-roading in a Viper, especially with a little crosswind control.

Like Crewdawg said, the NWS will often turn off on taxi-back when the gas is pretty low. It's a little scary because you have no indication that it happened (other than the tiny light among 100 other tiny lights) until you try to make a turn and keep going.

You can also steer with the brakes pretty well, but it's not recommended due to abnormal wear.

As a missile step switch, it will also step between different air-ground munitions, which can be handy if you have different settings selected for like munitions, such as JDAM.
Offline

IDCrewDawg

Forum Veteran

Forum Veteran

  • Posts: 857
  • Joined: 22 Apr 2004, 16:54
  • Location: Florida

Unread post11 Sep 2004, 01:16

The NWS doesn't reengage untill a lower ground speed reading. I believe 25 knts, but it could be as high as 35 knts. Prevents the pilot from engaging the NWS prematurely.
Offline
User avatar

Gums

Elite 2K

Elite 2K

  • Posts: 2583
  • Joined: 16 Dec 2003, 17:26

Unread post11 Sep 2004, 02:31

yo Ho!

Crew dawg and StandbyGains( ask about stbygains one day) has it really well.

The jet has such an aft C.G. that it is possible to have the switch in the nose gear disable nosewheel steering.

Back when the earth was still cooling and we were collecting roadkill from the T-rex troops, we used to use the manual fuel transfer doofer in order to move the C.G. forward. This procedure was supposed to help we dweebs from getting into a deep stall.

In any case, we would then have to move the switch to transfer fuel back to the rearmost tank. As we were dweebs, many of us would forget and by the time we landed most of the internal fuel was waaaaaaayyyyy back. Were it not for the FLCS, we would have departed at the break over the numbers.

We knew we had screwed up when the nose was really high turning off the runway and the NWS didn't work.

I think I related this a long time ago on this forum. One day I had so much fuel in the aft tank that when I stepped off the ladder the jet rested back on the tail!!!!!

No biggie, and the crew chief and I pulled her back down and held her until we got fuel loaded.

out,
Gums
Viper pilot '79
"God in your guts, good men at your back, wings that stay on - and Tally Ho!"
Offline

EriktheF16462

Forum Veteran

Forum Veteran

  • Posts: 540
  • Joined: 19 Mar 2004, 18:24

Unread post13 Sep 2004, 14:12

That WOW switch can get you in other ways too. If on the ground you apply -60 and the switch is depressed then you get probe heat. Then you melt covers and the pointy heads hate you. Years ago I put in a suggestion to include inspecting the switch in the 10jg safe for maintencance but was shot down. Now it is in there. Some other shmuck got the cash and when I put it in I was told, "Oh, that never happens." whe it happened to me and no one believed me. They all tried to say I did not inpsect the cockpit switches which was untrue. I cover my butt and look at the cockpit.
F16 462 AD USAF. Crew dog for 3 and Even a pointy head for a few months.
Offline

jeroen

Enthusiast

Enthusiast

  • Posts: 24
  • Joined: 09 Jun 2004, 18:41
  • Location: The Netherlands

Unread post14 Sep 2004, 08:43

Hey

Thanks for all the information!

IDCrewDawg wrote:The NWS doesn't reengage untill a lower ground speed reading. I believe 25 knts, but it could be as high as 35 knts. Prevents the pilot from engaging the NWS prematurely.

IDCrewDawg, do you mean this during landing? The block 52 checklist says that the pilot must engage the NWS as soon as (s)he has slown down to 80 knots, do you mean to say that the NWS is temporarily shut off when the viper is slowing down on the runway?

STBYGAIN wrote:That would be a little dicey. That's a fast way to go off-roading in a Viper, especially with a little crosswind control.

STBYGAIN, why would a viper go off-roading when the pilots engages the NWS at 80 knots? He kneed to be able to steer during landig doesn't he?

Why does the pilot has to disengage the NWS during take-off when it could be done automatically (the WOW switch feels the stut is fully extended)...

I really hope I am not annoying you...

Jeroen
Next

Return to F-16 Procedures

Who is online

Users browsing this forum: No registered users and 1 guest