Anti-skid proper behaviour?

[raelias]

Thing is you keep stating things that are not beeing disputed... I just posted some testing on the center focus on the thread that seems to confirm that antiskid is not currently working in the hornet

[Bond 42]

Anti-skid proper behaviour?

 

Raelias,

 

I just got done testing it myself. I ended up with the same stopping distance with antiskid on and off. Only difference I noted was it was harder to keep it in a straight line. Skid marks looked exactly the same also. So I think you’re on to something... I’m using the latest Beta.

[raelias]

Here is tacview chart speed/time:

 

Dark blue is with anti skid on, and light blue is with anti skid off. It's almost identical.

 

This is great, so def still not implemented, pitty

[mvsgas]

Is this part of your testing;

 

 

CAUTION

ANTI SKID caution does not reappear

and brakes may not be available for

13-1/2 seconds after cycling anti-skid

switch inflight or 9-1/2 seconds during

landing rollout, until BIT is completed.

 

 

7.3.6 Braking Technique. Above 40 knots, use

heavy to moderate braking after rollout consistent with

runway length/conditions. For maximum braking with

anti-skid above 40 knots, full brake pedal pressure

(approximately 125 pounds) should be used. Longitudinal

pulsing can probably be felt as the anti-skid cycles. As

aircraft decelerates below 40 knots, heavy brake

pressure should be relaxed to prevent wheels

from locking. Below approximately 35 knots,

anti-skid is inoperative and brakes must be judiciously

applied to prevent tire skids. When using

brakes below 35 knots, apply firm, steady brake

pedal pressures. Avoid light brake applications

or directional control by differential braking.

Edited March 1, 2019 by mvsgas

[CBStu]

A couple of thoughts and a Q. 1- Anti skid is better than a human because it can work on any wheel individually. Human can only control brakes of all wheels the same. So, if human feels one wheel locking up, the only way to stop it locking is to reduce the braking effort of all wheels to the level that one wheel (with the least traction) can support. 2- In a car w/ a bit of experience it isn't too difficult to feel a wheel locking and react. In a 33,000# plane w/ the wheels behind you I think it would be quite difficult to sense. Q- I have spent the last hour going through the FA-18 manual, Chuck's guide, forum search w/ no luck. I know I have seen a small window that can be overlaid on the screen while flying that shows control positions. Does this include throttle so I can see if we are at flight idle or ground idle? And how do I get it to display. Thanks for an interesting discussion.

[raelias]

A couple of thoughts and a Q. 1- Anti skid is better than a human because it can work on any wheel individually. Human can only control brakes of all wheels the same. So, if human feels one wheel locking up, the only way to stop it locking is to reduce the braking effort of all wheels to the level that one wheel (with the least traction) can support. 2- In a car w/ a bit of experience it isn't too difficult to feel a wheel locking and react. In a 33,000# plane w/ the wheels behind you I think it would be quite difficult to sense. Q- I have spent the last hour going through the FA-18 manual, Chuck's guide, forum search w/ no luck. I know I have seen a small window that can be overlaid on the screen while flying that shows control positions. Does this include throttle so I can see if we are at flight idle or ground idle? And how do I get it to display. Thanks for an interesting discussion.

 

You can notice the higher fuel flow when on flight idle, around 1000lbh

[mvsgas]

I know I have seen a small window that can be overlaid on the screen while flying that shows control positions. Does this include throttle so I can see if we are at flight idle or ground idle? And how do I get it to display. Thanks for an interesting discussion.

 

Right control and enter. I should show all control inputs.

[Tom Kazansky]

Does antiskid work on a rejected take off, too?

 

If so, I always have the problem of 1 mile long skid marks. With AS on or off. Is this like the real thing or is it not?

Edited March 1, 2019 by Tom Kazansky

[Eagle7907]

Anti-skid proper behaviour?

 

A couple of thoughts and a Q. 1- Anti skid is better than a human because it can work on any wheel individually. Human can only control brakes of all wheels the same. So, if human feels one wheel locking up, the only way to stop it locking is to reduce the braking effort of all wheels to the level that one wheel (with the least traction) can support. 2- In a car w/ a bit of experience it isn't too difficult to feel a wheel locking and react. In a 33,000# plane w/ the wheels behind you I think it would be quite difficult to sense. Q- I have spent the last hour going through the FA-18 manual, Chuck's guide, forum search w/ no luck. I know I have seen a small window that can be overlaid on the screen while flying that shows control positions. Does this include throttle so I can see if we are at flight idle or ground idle? And how do I get it to display. Thanks for an interesting discussion.

 

 

 

Like what raelias said, fuel flow, even the engines spooled a bit higher than usual when on the ground. There isn’t really a physical throttle position for flight idle and ground idle. It will be the same. The different idling power is determined by if the jet knows it is on the ground or not, then the engines will utilize the proper idle rpm. That’s what I was saying is sometimes the jet won’t go into ground idle immediately at touchdown. Just be aware, and if you think it isn’t, just nudge the throttles up a bit then back to idle to get them to ground idle.

 

On a different note, I’m surprised that the engine anti-ice being left on doesn’t affect the idle speeds. Hmmm....

 

Sent from my iPhone using Tapatalk Pro

Edited March 1, 2019 by Eagle7907

[raelias]

So given the data on our findings should this be moved to bug report or something? I would like a dev to comment on the matter

[Flamin_Squirrel]

There isn’t really a physical throttle position for flight idle and ground idle.

 

Bizarrely for a relatively modern jet, there is!

 

A retractable inflight IDLE stop extends with weight off the wheels and provides a higher IDLE rpm and reduced acceleration time to MIL.

 

[Weta43]

It makes very little difference in the dry because the brakes don't cause skids on a surfaces with good traction. If they don't skid anyway, anti-skid makes no difference.

 

Try landing heavy in the wet and sitting on full brakes all the way down the runway.

 

Without antiskid the aircraft will start to skid as it slows and spin out, with antiskid it will maintain directional control.

Antiskid.trk

No_Antiskid.trk

No_Antiskid_2.trk

Edited March 2, 2019 by Weta43

[raelias]

It makes very little difference in the dry because the brakes don't cause skids on a surfaces with good traction. If they don't skid anyway, anti-skid makes no difference.

 

Try landing heavy in the wet and sitting on full brakes all the way down the runway.

 

Without antiskid the aircraft will start to skid as it slows and spin out, with antiskid it will maintain directional control.

 

Thats just so wrong, you can most def lock up your wheels in any surface there is WAY more then enough brake pressure for that

[Weta43]

I have no idea what expertise you have to say that.

Are you an F-18 pilot in real life ?

 

My guess is that probably depends very much on the weight of the aircraft and the surface you're braking on.

 

The maximum torque the brakes can exert on the wheel to stop it is fixed, but the amount of friction the tyres create - & so the torque exerted to keep the wheel spinning - is proportional to the weight of the aircraft, so more weight, harder to stop but less likelihood of a skid.

Wet runways drastically reduce the coefficient of friction...

 

Either way, in game anti-skid does stop skids from happening in the wet.

 

Edit - I only tried in the wet.

 

Someone had already made a video of the F-18 skidding in DCS in the dry with the anti-skid off.

jw1Da0LKN9s

Edited March 2, 2019 by Weta43

[Rainmaker]

Tried yesterday. No issue with skid with anti-skid enabled until slower speeds, which would be perfectly normal given system limitations.

[DirtySanchez]

What I like about simmers is how they "think", "guess", "suspect", and are "sure" of things they've never experienced, and their willingness to tell actual pilots how they must be wrong because the answer doesnt fit their limited academic understanding of a topic.

 

I could show you dozens of cases across dozens of aircraft types which prove that your average anti-skid braking system has PLENTY of power to lock the mains even on a dry, grooved, porous friction overlayed runway. From fighters to 747s. But unless someone is an F-18 pilot (and sometimes even if he is), the answer isn't good enough. Amazing.

 

This is not a debate. No human being can max-perform the braking system as well as the anti-skid does, hence with an operative anti-skid system all the pilot has to do is literally stand on the brakes until reaching taxi speed and he will have achieved the shortest landing distance possible...regardless of runway condition. With anti-skid inoperative, that technique will result in locked wheels, loss of directional control, blown tires, outrageous stopping distance, and probably a runway excursion.

 

The takeaway is obvious: while anti-skid doesn't change physics, a human pilot lacks tactile feedback regarding wheel speed and MUST use more conservative braking to prevent locking wheels, resulting in longer stopping distance compared to using anti-skid to threshold brake.

 

This is just fundamental knowledge possessed by anyone who operates airplanes with these types of systems. One look at the performance charts for any jet will depict separate "actual landing distance" penalties for wet/contaminated runways and for anti-skid inoperative.

[Bond 42]

What I like about simmers is how they "think", "guess", "suspect", and are "sure" of things they've never experienced, and their willingness to tell actual pilots how they must be wrong because the answer doesnt fit their limited academic understanding of a topic.

 

I could show you dozens of cases across dozens of aircraft types which prove that your average anti-skid braking system has PLENTY of power to lock the mains even on a dry, grooved, porous friction overlayed runway. From fighters to 747s. But unless someone is an F-18 pilot (and sometimes even if he is), the answer isn't good enough. Amazing.

 

This is not a debate. No human being can max-perform the braking system as well as the anti-skid does, hence with an operative anti-skid system all the pilot has to do is literally stand on the brakes until reaching taxi speed and he will have achieved the shortest landing distance possible...regardless of runway condition. With anti-skid inoperative, that technique will result in locked wheels, loss of directional control, blown tires, outrageous stopping distance, and probably a runway excursion.

 

The takeaway is obvious: while anti-skid doesn't change physics, a human pilot lacks tactile feedback regarding wheel speed and MUST use more conservative braking to prevent locking wheels, resulting in longer stopping distance compared to using anti-skid to threshold brake.

 

This is just fundamental knowledge possessed by anyone who operates airplanes with these types of systems. One look at the performance charts for any jet will depict separate "actual landing distance" penalties for wet/contaminated runways and for anti-skid inoperative.

 

 

 

Well said...You nailed it.

As someone posted earlier at this being a measuring contest.. that wasn’t my point for the back and forth. That’s the last thing I care about. I was simply trying to help people understand what is right vs wrong. We are all here for the same reason.. enjoy the sim. Keep an open mind, even professional pilots like myself and others learn something new.

[Bond 42]

So given the data on our findings should this be moved to bug report or something? I would like a dev to comment on the matter

 

 

 

I was going to mention this myself.. I think it that would be a good idea.

[Bond 42]

What I like about pilots is how they think that because they operate some vehicle, they automatically know everything about it than actual engineers designed that vehicle. The famous saying goes: “The more you know, the more you know you don't know.”. Pilots changed it to:

"The more I know, I know everything.”

 

They are better meteorologists than actual meteorologists; better lawyers than actual lawyers; they will teach Boeing engineer that designed some system about that system... and in fact, it's their knowledge that's quite superficial.

 

 

 

Lol you’re wild.

[Bond 42]

Unsettled ego?

 

 

 

If you actually knew me you’d know I have no inflated ego. You’re just an @ss. Simple.

[Flamin_Squirrel]

If you actually knew me you’d know I have no inflated ego.

 

You behaviour in this thread indicates otherwise. You've refused to listen to anything anyone else has said from the get-go.

 

And I've seen 747 captains misunderstand some basic principles, so in that regard Nikola is correct.

Edited March 2, 2019 by Flamin_Squirrel

[Kazius]

I have no idea what expertise you have to say that.

Are you an F-18 pilot in real life ?

 

My guess is that probably depends very much on the weight of the aircraft and the surface you're braking on.

 

The maximum torque the brakes can exert on the wheel to stop it is fixed, but the amount of friction the tyres create - & so the torque exerted to keep the wheel spinning - is proportional to the weight of the aircraft, so more weight, harder to stop but less likelihood of a skid.

Wet runways drastically reduce the coefficient of friction...

 

Either way, in game anti-skid does stop skids from happening in the wet.

 

Edit - I only tried in the wet.

 

Someone had already made a video of the F-18 skidding in DCS in the dry with the anti-skid off.

jw1Da0LKN9s

 

terrible video to use as an example. The guy wasn't trimmed properly, was jerking the stick all over the place, was about 150+ knots at the threshold. The way he landed he probably would still have skidded sideways even with anti-skid on.

[Bond 42]

You behaviour in this thread indicates otherwise. You've refused to listen to anything anyone else has said from the get-go.

 

And I've seen 747 captains misunderstand some basic principles, so in that regard Nikola is correct.

 

 

 

You’re just as crazy as Nikola. Read the whole thread. This isn’t about me not listening. I’ve never blocked anyone, but you and Nikola are the first. Take care.

[CBStu]

...No human being can max-perform the braking system as well as the anti-skid does, hence with an operative anti-skid system all the pilot has to do is literally stand on the brakes until reaching taxi speed and he will have achieved the shortest landing distance possible...regardless of runway condition...

Exactly. When ABS first appeared in cars there was often a struggle to get people to understand how to use it. In those days the hydraulics cycling was quite noticeable. A lot of people hit the pedal, got the ABS going, felt and heard the cycling, and thought something was wrong. So they released brake pressure. Now the cycling is much less noticeable. I think the hardware, and certainly the computing power, are much better so it's higher frequency, lower amplitude cycling. In any car w/ ABS the technique is hit the pedal as hard as you can and hold it. Steer if you need to. As an aside, many of the cars have graduated to also include stability control. One facet of that is the opposite of ABS- it is the ability to apply the brake. It is amazing to feel what applying one brake can do to help a car straighten out if it gets squirrely.

[Eagle7907]

Anti-skid proper behaviour?

 

Bizarrely for a relatively modern jet, there is!

 

 

 

That’s odd. So then answer his question. Where is the flight idle position and how does he get it? Because Id love to see how that is even possible in the sim. I haven’t seen a difference.

 

 

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