Brakes on landing

[kylania]

I've been kinda pumping the breaks while I land, seems to work OK.

[ZaltysZ]

If you don't use axis for brakes, you have to tap the brake button or else you will be applying full brakes. If you use axis for brakes, you can and need to apply brakes by small amount. Most runways have more than enough length, so there is no reason for aggressive braking.

[Frederf]

I also cant get brakes. Under setup the wheelbrake line on/off is blank but the next line is "W" for brakes. no way to select the other line.

 

The two lines are slightly different, showing "On" and "On/Off." It must be something about how the command interacts with joystick buttons vs. keyboard keys that means they have to be separate commands. They do the same thing. I think one turns the brake behavior cycle on when keyboard key is pressed and turns the brake behavior cycle off when the keyboard key is released (thus On/Off) while the DX joystick button only has "button present" and "button absent" instead of press and release (thus present=On).

 

Interesting. I just went flying again.

 

After braking for a bit... L-HYD PRES starts blinking on the caution panel and braking force is much reduced....

 

If you don't use axis for brakes, you have to tap the brake button or else you will be applying full brakes. If you use axis for brakes, you can and need to apply brakes by small amount. Most runways have more than enough length, so there is no reason for aggressive braking.

 

Really there are two bugs going on here. The first one is that ANY of the 7 brake commands beyond 0% activation will result in maximum braking application despite the RCtrl-Enter indication. This includes both keyboard and axial commands. "Tapping W" simply applies full pressure so briefly that the physical system is unable to keep up and skidding or anti-skid activation is averted. The exact same behavior would be seen by tapping the axial commands.

 

The second "bug" is related to anti-skid. Whenever the A/S system kicks in to prevent skidding there is a related drop in the appropriate hydraulic system. This may or may not be normal behavior for the real lift A/S system. The binary on/off braking simply compounds this behavior since the A/S system has to work overtime whenever braking is applied thus the unusual dropping of the appropriate hydraulic system pressure. Without A/S system armed the hydraulic system does not suffer excessive pressure drop.

[sobek]

Without A/S system armed the hydraulic system does not suffer excessive pressure drop.

 

True, but you might pop a wheel. :(

[nomdeplume]

The binary on/off braking simply compounds this behavior since the A/S system has to work overtime whenever braking is applied thus the unusual dropping of the appropriate hydraulic system pressure.

 

I have found that when landing I can apply partial brakes and the hydraulic pressure does not drop. If I apply full brakes then it does drop and eventually the warning light starts flashing and I have to ease off to let the pressure build.

 

While I do think the brakes are too aggressive with not enough variance between slight pressure and full pressure, I also think different amounts on the brake axis does actually result in different behaviour in the sim - it's not strictly "on or off". OTOH, drain on the hydraulics may be modeled independently to the stopping force exerted by the brakes.

[Frederf]

The hydraulic pressure drop is related to the brake controller input (i.e. the triangles on RCtrl-Enter). So yes, you can limit the hydraulic pressure loss by applying partial control input.

 

However when it comes to actual brake application there is only none and full. The switchover happens at exactly 15% of the controller input. That is absolutely strictly on/off. I've tuned by controller down to exact saturation and I get no braking at 15 and full braking at 16 saturation percent.

[bfeld]

Frederf, there were also other threads related to this problem. But there was no explanation or solution. If I remember correctly, there were people stating they do not have any problems (but maybe they are referring to the RCtrl-Enter ouput). Hence, since I experience this behaviour, too, my question:

Is this your observation or a confirmed bug?

[Frederf]

I'm guessing that A/S activation is programmed to be a dip in the hydraulic pressure. However on harder brake pressures the dip keeps occurring over and over very fast without a chance for the pressure to recover which drives the pressure down down down.

 

As a temporary fix I set my saturation on my toe brake axes to 20% so at the most I'm using 20% pressure (so, full lockup pressure since it's over 15%) and I'll only get hydraulic system pressure dipping associated with up to 20% pedal application.

[JeffC]

Is not the on/off a momentary, either on or off? and the wheelbrake (line that on mine is not editable) is for pushing as long as you need it?

[Frederf]

Nope, they behave exactly the same. Once pressed they build according to a time constant.

[Tango]

A/S should actually result in an increased, though pulsing, hydraulic pressure. After the initial surge, the hyd pump should maintain the pressure along with the accumulator so there shouldn't be much reduction even under heavy braking and anti-skid operation if everything is working correctly.

 

At the moment it appears the A/S operation is bypassing the accumulator.

 

Best regards,

Tango.

[JeffC]

Well mine doesn't work

[Steel Jaw]

You can also "aerobrake" like I do by keeping the nose up and letting the body of the jet hit the slipstream at an oblique angle that has high air resistence. Been doing that in Falcon for years. Don't be in a hurry to plant the nose wheel on the runway: let it fall down on its own while holding back preasure.

[hassata]

Is there a difference between the 'Brake On' command assigned to W, and the 'Brake On/Off' command which you can assign to a DX button?

[Teej]

I'll say this much...I'm not sure about the super short runways but you have no excuse for overrunning at Kutaisi.

 

Just to test, I took off at 111% MTOW (loaded with Mk84, CBU and fuel) went out a couple of miles, turned around and landed. Did what I could with aerobraking and dirtying up the a/c....didn't touch the brakes until I was down to about 75 knots and stopped w/o low hyd pressure.

[Frederf]

Is there a difference between the 'Brake On' command assigned to W, and the 'Brake On/Off' command which you can assign to a DX button?

 

Only that you can't assign one to a keyboard and one to a DX button. They behave the same functionally.

[JeffC]

Ok, finally got brakes. Had to use a key on joystick, but hey they work. "W" key still does not work.

The brakes do not seem to be aggressive enough.

[Frederf]

Try it without anti-skid on. They are plenty aggressive as you'll leave black streaks everywhere!

[Mike Busutil]

Brakes Suck???

 

When I land, I press the W key to brake. the problem I am having is it takes nearly the whole runway to stop.... I am using full flaps on the approach and touch down speed is around 120ish if I remember correctly. But even if I land on the numbers, sometimes I will be in the grass on the other side of the runway because the brakes just don't stop her. My hydraulic pressure is good, it just feels like there are no pads left. Any ideas?

[copen]

I *believe* you need nose wheel steering (NWS) on to engage the wheel brake. One time I forgot to turn on NWS, and the brake never seemed to engage. I could tell, b/c I was only taxiing at slow speed, so the brake effect should have been obvious. Turned on NWS, and the brake functioned properly after that.

[Frederf]

NWS and brakes are independent.

 

If you press and hold W (confirm triangles fill with RCtrl-Enter) then one of two things will happen: With anti-skid off the tires will lock up and skid for miles. With anti-skid on the hydraulic pressure will plummet on anti-skid activation.

[Mike Busutil]

Same issue here....

[alphie]

Yep, Ive come close to turning off anti-skid, blowing all three tires then shooting the tower the bird.

 

Brakes are very soft in this version of beta.

 

Does the A10 not have a reverse thrust? That would help a lot with these wimpy brakes.

[MTFDarkEagle]

Don't hold the brakes guys! Keep an eye on the L-hyd pressure --> with a/s on, and you stamp and hold the brakes, the pressure drops a lot, and you have very little braking power. Adjust your braking to your hyd pressure, and you should be fine.

 

And no, the A-10 does not have reverse thrust --> weight, and what for?

[Joe Lighty]

Don't EVER try to land with a tailwind. In the airliner I fly, we can land in 3200 ft usually, but with a 10 knot tailwind it would take something along the lines of 11000 ft. Careful there. No wet runways until you work out this brake problem as well would be my advice.

 

What? Sorry, you've confused me. What "airliner" do you fly that can land in 3200 feet but the landing distance will increase to 11000 with a 10 knot tailwind? Are you talking ALD or LFL?

 

Hope you can clear it up for me!

 

Joe

Edited November 30, 2010 by Joe Lighty