Anti-skid proper behaviour?

[raelias]

Hello,

 

I was wondering about the anti-skid, is it suppose to leave all those long skid marks on the runway? Thats now how it works on commercial aircraft but I'm unsure about the hornet, I would think not. Also i feel like because of this behaviour the brakes are pretty unefficient, can anyone confirm or deny this hipotesis?

[Rennes]

I'm not certain, but I believe the anti-skid just keeps the wheels from locking up during breaking.

I think what you are talking about is were the wheels are spun up prior to touchdown?

[Scofflaw]

I haven't tried comparing heavy vs light, but I often take most of the runway trying to bring the 18 to a halt.

 

I remember reading the 18 has better brakes than the 16, so I don't think I'll be able to stop the 16 before running out of runway unless I correct whatever I'm doing wrong.

[AKarhu]

I haven't tried comparing heavy vs light, but I often take most of the runway trying to bring the 18 to a halt.

 

I remember reading the 18 has better brakes than the 16, so I don't think I'll be able to stop the 16 before running out of runway unless I correct whatever I'm doing wrong.

At heavy weights, the F-18 is somewhat prone to end up with hot brakes even if its landing speeds are fairly slow. I doubt, on the other hand, that the stopping distance would be any worse than other comparable aircraft of similar weights.

[mvsgas]

Hello,

 

I was wondering about the anti-skid, is it suppose to leave all those long skid marks on the runway? Thats now how it works on commercial aircraft but I'm unsure about the hornet, I would think not. Also i feel like because of this behaviour the brakes are pretty unefficient, can anyone confirm or deny this hipotesis?

 

What is your point of reference here? What make you believe its wrong? How do you think it should behave? Do you have a comparison a document or is it all base on you perception?

 

Tire marks on runway and taxi way are common. Why? Because aircraft tires are relatively soft rubber compounds. Look at most airbases and you will see tire marks on many taxiways and parking spots. Look at Nellis in google maps. While car tires last years, and it take to lock the brakes to leave tire marks, I seen aircraft leave tire skid marks just by turning and tires only last a few months at best.

 

Anti skid helps prevent (not eliminate) tire failure and improves control under braking condition. Could you stop faster without it? Probably, if you don't manage to blow the tires and loose control in the process. If you can't stop during landing on any aircraft, you are going to fast, are to heavy, the runway is not long enough or a combination of all three.

Edited February 27, 2019 by mvsgas
spelling

[Rainmaker]

As referenced above, belive you are talking about initial touchdown, which has nothing to do with anti-skid.

 

Skid detection on pretty mich every mil aircraft out there requires wheels to be spinning at a minimum speed (speeds vary between aircraft) as they use speed detectors in the hubs themselves to measure spin differential between wheels. As such, anti skid is inoperable at slow taxi speeds anyway, so locking the brakes up is easily done and not an indication of the system not working properly.

[Eldur]

All I noticed is that besides leaving tyre marks even with anti skid on with just enough braking power the controllability gets quite spongy and I even can hear the tyres screeching a little bit, as if the plane's just sliding on locked wheels. If this is correct, I can't say.

[Rennes]

I believe I recall one of the former hornet pilots on here (or maybe Jello) saying that when breaking without anti-skid it was a very fine line between no breaks and blowing a tire.

[=Panther=]

[..] so I don't think I'll be able to stop the 16 before running out of runway unless I correct whatever I'm doing wrong.

 

If landing at correct speed, the viper is aero-braked on touch down. Keep the nose at 10° up until below 100kts and let it slowly come down. If done correctly, you will have plenty of runway remaining.

[Eagle7907]

Hey fellas,

 

Not sure if this is correct or not but you may want to check to see if your engines go to ground idle. I’ve noticed multiple times that they don’t after landing and hinders your braking efforts. To check I always quickly come up off idle then back to make sure the engines are spoiled back.

 

 

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[Scofflaw]

Hey fellas,

 

Not sure if this is correct or not but you may want to check to see if your engines go to ground idle. I’ve noticed multiple times that they don’t after landing and hinders your braking efforts. To check I always quickly come up off idle then back to make sure the engines are spoiled back.

 

Good point - this has happened to me many times and makes a big difference.

[Eagle7907]

Again I’m not sure, but I’ve noticed this happens mainly if you flare the landing. I haven’t fully tested this because I read where Mover or Lex stayed that if you flare a switch won’t fully compress. Not sure if it’s related? Anyways, just a thought from the notion about landing roll.

 

 

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[Tholozor]

According to the NATOPS regarding landings, using a flared landing may not properly engage the WOW sensor immediately to switch the engine from flight idle to ground idle. Aero braking is not recommended.

 

 

[raelias]

As referenced above, belive you are talking about initial touchdown, which has nothing to do with anti-skid.

 

I'm not talking about touchdown, I'm talking about the landing roll while on breakes if you hold it it will leave skid marks on the runways all the way behind you until almost the point where you stopped, doesn't seem like something that should happen because the anti-skid is suppose to prevent the wheels from locking therefore it should leave no skidmarks during the braking phase even if you apply maximum manual brake.

 

What is your point of reference here? What make you believe its wrong? How do you think it should behave? Do you have a comparison a document or is it all base on you perception?

 

It's all based on the perception of every aircraft i even flew with an anti-skid that doesn't behave like that, those are of course civilian jets so that's why I'm asking if anyone (i.e a hornet or another former fighter pilot) can confirm this behaviour, you don't have to be rude about it I'm just asking a question based of real world anti-skid behaviour on civilian aircraft since I'm not a fighter pilot.

[Eagle7907]

According to the NATOPS regarding landings, using a flared landing may not properly engage the WOW sensor immediately to switch the engine from flight idle to ground idle. Aero braking is not recommended.

 

 

 

 

 

 

 

 

 

Ah! Thank you Tholozor.

 

So this could be the problem? Just something to pay attention to when you use up lots of runway to stop.

 

 

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[Bond 42]

What is your point of reference here? What make you believe its wrong? How do you think it should behave? Do you have a comparison a document or is it all base on you perception?

 

Tire marks on runway and taxi way are common. Why? Because aircraft tires are relatively soft rubber compounds. Look at most airbases and you will see tire marks on many taxiways and parking spots. Look at Nellis in google maps. While car tires last years, and it take to lock the brakes to leave tire marks, I seen aircraft leave tire skid marks just by turning and tires only last a few months at best.

 

Anti skid helps prevent (not eliminate) tire failure and improves control under braking condition. Could you stop faster without it? Probably, if you don't manage to blow the tires and loose control in the process. If you can't stop during landing on any aircraft, you are going to fast, are to heavy, the runway is not long enough or a combination of all three.

 

 

 

You won’t stop faster with anti-skid off. You’d take a big penalty and be prone to popping tires.

 

I think what OP is getting at is the constant skid marks you’ll get when on the brakes? Which in real life won’t be correct with anti-skid on. I’ve noticed it myself..

[raelias]

I think what OP is getting at is the constant skid marks you’ll get when on the brakes? Which in real life won’t be correct with anti-skid on. I’ve noticed it myself..

 

Thats exactally what I'm saying

[mvsgas]

You won’t stop faster with anti-skid off. You’d take a big penalty and be prone to popping tires.

 

I think what OP is getting at is the constant skid marks you’ll get when on the brakes? Which in real life won’t be correct with anti-skid on. I’ve noticed it myself..

 

Thats exactally what I'm saying

 

The problem is the correlation your guys are making. Skid marks does not mean tire lock up.

[Svend_Dellepude]

If landing at correct speed, the viper is aero-braked on touch down. Keep the nose at 10° up until below 100kts and let it slowly come down. If done correctly, you will have plenty of runway remaining.

 

AFAIK it's 13° AoA for the shortest run. If I'm not mistaken, 13° is also marked on the AoA indicator. Do not exceed 15°.

If you are still talking about the Viper, that is.

[Kazius]

I haven't tried comparing heavy vs light, but I often take most of the runway trying to bring the 18 to a halt.

 

I remember reading the 18 has better brakes than the 16, so I don't think I'll be able to stop the 16 before running out of runway unless I correct whatever I'm doing wrong.

 

Make sure as soon as you touch down you apply full airbrake and then pull back on the stick to add additional drag from the stabilizers defecting air. Also if your landing on a runway you are allowed to flare which also bleeds a bit of speed before the wheels touch. Only thing you can't really do in the F-18 is aerobrake. Not sure if real life F-18's can do it, never see them aerobrake in videos either though.

 

At Nellis, landing on the target point, I can usually reduce speed to 20-30 knots well before the first taxi turn.

 

I should have continued reading the post, just noticed someone posted the manual info :)

Edited February 28, 2019 by Kazius

[Deano87]

As pointed out double checking that the engines go back to ground idle makes a huge difference in landing distance.

[raelias]

As pointed out double checking that the engines go back to ground idle makes a huge difference in landing distance.

 

Seriously?

[raelias]

The problem is the correlation your guys are making. Skid marks does not mean tire lock up.

 

Nor should they be produced by a tire not spinning significantly slower they your ground speed, which is the anti-skid job to prevent

[Bond 42]

Anti-skid proper behaviour?

 

The problem is the correlation your guys are making. Skid marks does not mean tire lock up.

 

 

 

Not to stir the pot.. but would would that exactly mean then? Lol you will not have “skid marks” in real life without tire lockup of some sort.

 

That being said, it seems like every aircraft does the same thing on here. So maybe it’s just a DCS thing when apply brakes? Doesn’t mean it’s “locked up” in dcs standards but just a graphic?

Edited February 28, 2019 by Bond 42

[Flamin_Squirrel]

Not to stir the pot.. but would would that exactly mean then? Lol you will not have “skid marks” in real life without tire lockup of some sort.

 

Rubbish. Lock up means 0 wheel rotation. Optimum braking is often achieved with a certain amount of wheel slip, around the 10% mark (i.e. wheels rotating 10% less than ground speed). So no, leaving rubber behind does NOT mean a lockup occured.