Increase brake effectiveness in F/A-18C

Ground roll does not change. Flaring only puts the touchdown point further down the runway but does not change the ground roll distance.

 

I suspect this is where you are making the mistake.

 

The chart presents ground roll distance. The distance from touchdown to full stop.

That’s also the wrong chart, DCS hornet uses the EPEs.

That’s also the wrong chart, DCS hornet uses the EPEs.

The 402 achieves its higher performance mainly due to higher rpms and temps. I severely doubt that idle thrust is significantly higher compared to the 400 engine.

1. If you flare it takes longer to get the weight onto the wheels after touchdown.

Only if you do a flared minimum descent rate landing (A greaser). Short field landing technique in aircraft with WOW systems is a zero float flare with a firm touchdown. The same would apply here.

2. ? The correct procedure is to maintain thrust and attitude to touchdown.

Again, it matters not how you arrive at the touchdown point (assuming touchdown compresses the gear enough to close the prox switches). Ground roll is solely determine by four things. Gross weight at touchdown, speed at touchdown, power to idle after WOW and braking technique.

3. I'm looking forward to the results (with the correct stable thrust & attitude/speed method)

Once I get time I to do some landings I will post my results. I expect they will closely match the charts.

1. Again, it matters not how you arrive at the touchdown point (assuming touchdown compresses the gear enough to close the prox switches).

2. Ground roll is solely determine by four things. Gross weight at touchdown, speed at touchdown, power to idle after WOW and braking technique...

1. Of course it does matter. If you e.g. decrease thrust while still in the air, the total energy at touchdown will be noticable reduced. The ROD will increase and/or the speed will decrease as well.

2. You missed an important fifth one, energy.

With this non-standard method the landing roll will be naturally shorter.

The 402 achieves its higher performance mainly due to higher rpms and temps. I severely doubt that idle thrust is significantly higher compared to the 400 engine.

You doubt and assume but you don't know. Why are you ignoring variables that could effect your results? How can you claim ED is wrong when you don't have the data to back it up?

You doubt and assume but you don't know. Why are you ignoring variables that could effect your results? How can you claim ED is wrong when you don't have the data to back it up?

If you know even approximate idle thrust values for various jet engines it's not exactly difficult to figure out that even a noticeable thrust difference at idle thrust can't be responsible for a 50% longer landing roll. (not even 10%)

And it doesn't explain the antiskid bug either.

I agree with bbrz on anti skid vs no anti skid issue. I mean, if your wheels are locking up in dry conditions even with anti skid on, there's a problem... :(

Looks like this didn't get simulated properly...

Again this 50% you keep mentioning is based on the wrong charts, to begin with, all these variables add up.

Not being in ground idle,

landing at a high gross,

not measuring the ground roll distance right,

not using the speed brake or full aft stick,

locking the wheels,

It all adds up on the ground roll. So at this point it's your word against theirs, because ED has officially stated multiple times that the brakes are accurately represented. It seems like your deliberately ignoring evidence that could contradict your hypothesis.

So at this point it's your word against theirs, because ED has officially stated multiple times that the brakes are accurately represented. It seems like your deliberately ignoring evidence that could contradict your hypothesis.

Thanx for pointing out all the variables but after a few decades of simulated and RW flying (+17000hrs) I know how to read charts and how to fly with high precision.

If you think that it is correct that locked/sliding wheels (how would this be possible with a working antiskid system?) have the same friction as rolling wheels, then I don't honestly don't know what to reply.

But since ED numerous times said everything is fine, this discussion doesn't make any sense and it's only a waste of time.

do we know for sure that runways of variable "slipperiness", for want of a better word, are modelled within DCS and if they aren't, could the standard friction factor be high enough so that the anti-skid system never kicks in?

however, i guess that if that is the case, it would tend to make reports of poor braking performance unlikely.

i just don't recall seeing anything about the attributes of runways changing as a result of the weather for example.

1. Of course it does matter. If you e.g. decrease thrust while still in the air, the total energy at touchdown will be noticable reduced. The ROD will increase and/or the speed will decrease as well.

2. You missed an important fifth one, energy.

 

With this non-standard method the landing roll will be naturally shorter.

The formula above is Kinectic energy. The M is mass or gross weight at touchdown. The V is velocity or airspeed at touchdown.

If you also read carefully, you will see that I state thrust to idle AFTER WOW (Weight On Wheels)

To quote myself:

Ground roll is solely determine by four things. Gross weight at touchdown, speed at touchdown, power to idle after WOW and braking technique.

Since you have determined that you are the only one who can execute the landing technique correctly it would be rather pointless to post my results, wouldn't it?

Thanx for pointing out all the variables but after a few decades of simulated and RW flying (+17000hrs) I know how to read charts and how to fly with high precision.

 

If you think that it is correct that locked/sliding wheels (how would this be possible with a working antiskid system?) have the same friction as rolling wheels, then I don't honestly don't know what to reply.

 

But since ED numerous times said everything is fine, this discussion doesn't make any sense and it's only a waste of time.

I don't care about YOUR experience, I don't care about other jets or how they perform. I only care about the performance of the F/A-18C Lot 20 with the 402s circa 2005. So unless you personally have experience with that particular platform, none of that matters. In fact, it might even bias your expectations negatively because the hornet is very different from most fighters.

This is exactly the way the gun accuracy thread, the take off pitch thread, and JDAM cycle threads went.

The point is, It's ED sim and I'm gonna take their side every time unless you can prove them wrong with proof NOT guesses based on your experience. Because they do have access to the correct charts, and they do have access to SMEs who flew the aircraft from that time, and they have done extensive testing, and are a respected business, not some person from the internet. If they say its right, I'll believe its right. So unless your gonna tell us you know more about the jet then they do, then your right this is a waste of time.

I don't care about YOUR experience, I don't care about other jets or how they perform. I only care about the performance of the F/A-18C Lot 20 with the 402s circa 2005. So unless you personally have experience with that particular platform, none of that matters. In fact, it might even bias your expectations negatively because the hornet is very different from most fighters.

 

This is exactly the way the gun accuracy thread, the take off pitch thread, and JDAM cycle threads went.

 

The point is, It's ED sim and I'm gonna take their side every time unless you can prove them wrong with proof NOT guesses based on your experience. Because they do have access to the correct charts, and they do have access to SMEs who flew the aircraft from that time, and they have done extensive testing, and are a respected business, not some person from the internet. If they say its right, I'll believe its right. So unless your gonna tell us you know more about the jet then they do, then your right this is a waste of time.

I will disagree slightly.

Airplanes are airplanes when it comes to things like maximum performance landing.

I've never flown a real F/A-18 or any other Jet Fighter for that matter but I have flown plenty of jets with similar WOW systems and they all say the same things as the F/A18 manual.

To achieve book numbers, land on your spot at X speed and Y weight firmly so that the WOW system knows it has arrived, and apply maximum braking, using back stick to keep the main wheels in positive contact.

That technique yielded a number that basically matched the book the first time I tried it in the F/A-18. It was off 200 feet long mainly because I delayed max brakes. (Something that happens in real airplanes too. Its hard to jump the brakes on touchdown with plenty of runway out ahead of you)

If you also read carefully, you will see that I state thrust to idle AFTER WOW (Weight On Wheels)

 

Since you have determined that you are the only one who can execute the landing technique correctly it would be rather pointless to post my results, wouldn't it?

I don't get it. First you are stating that my 'mistake' is, to touchdown at constant thrust and at a constant attitude.

Now you are saying, idle after touchdown. Do you reduce power before touchdown or not?

If you do, your energy at touchdown will be lower, if not, where's the difference to the correct 'book' method?

Weird and wrong assumption. I'd say most people here are able to perform the landing correctly. It's you who's still not able to explain how you actually fly the approach and touchdown.

I don't get it. First you are stating that my 'mistake' is, to touchdown at constant thrust and at a constant attitude.

 

Now you are saying, idle after touchdown. Do you reduce power before touchdown or not?

 

If you do, your energy at touchdown will be lower, if not, where's the difference to the correct 'book' method?

 

Weird and wrong assumption. I'd say most people here are able to perform the landing correctly. It's you who's still not able to explain how you actually fly the approach and touchdown.

You primary issue is reading for comprehension here and, most likely, in the manuals.

Here is everything I posted in this thread.

What chart are you using to determine this? Please post it so others can confirm your results.

 

I just flew a quick test.

 

Batumi Standard Day No Wind

 

Weight at Touchdown 36400 lbs

 

Chart says ground roll of 3900 feet. I stopped in 4100 feet. I was a half second late getting full brake pressure on touchdown.

 

I would say there is either a misunderstanding of the chart or the technique involved in duplicating the results.

Ground roll does not change. Flaring only puts the touchdown point further down the runway but does not change the ground roll distance.

 

I suspect this is where you are making the mistake.

 

The chart presents ground roll distance. The distance from touchdown to full stop.

 

Testing at higher weights is more valid for brake effectiveness but I am sure I can replicate my results at any weight.

 

No comment on AS on or off.

Only if you do a flared minimum descent rate landing (A greaser). Short field landing technique in aircraft with WOW systems is a zero float flare with a firm touchdown. The same would apply here.

 

 

 

Again, it matters not how you arrive at the touchdown point (assuming touchdown compresses the gear enough to close the prox switches). Ground roll is solely determine by four things. Gross weight at touchdown, speed at touchdown, power to idle after WOW and braking technique.

 

 

Once I get time I to do some landings I will post my results. I expect they will closely match the charts.

 

The formula above is Kinetic energy. The M is mass or gross weight at touchdown. The V is velocity or airspeed at touchdown.

 

If you also read carefully, you will see that I state thrust to idle AFTER WOW (Weight On Wheels)

 

To quote myself:

 

Gross weight at touchdown, speed at touchdown, power to idle after WOW and braking technique.

 

Since you have determined that you are the only one who can execute the landing technique correctly it would be rather pointless to post my results, wouldn't it?

I never mention you, your technique or any ambiguity as to whether or not I delay idle power until after WOW.

I have done a few more landings at various weights and reproduce book results within 10% which is what I would expect in a real airplane.

I'm convinced the brake effectiveness in the DCS F/A-18 is close enough to be considered accurate.

If you are achieving ground roll distances that differ from the book by 50% consistently there is an error in your technique, chart usage or both.

In an attempt to lighten the mood a little, I've attached a couple of tracks for your consideration and probable amusement. :smilewink:

I saved a track of my first attempt at one of the VFR landing missions that comes with the Hornet. OK, i didn't fly the pattern, but that wasn't the point. The first track i recorded was with anti-skid on and i brought the aircraft to a complete stop, so that i could see where i ended up. I did use the airbrake and stood on both brake pedals as soon as i touched down and i pulled back on the stick at below 100knots.

I then replayed the track and took control just before touchdown, turning off anti-skid and bringing the plane to a halt in the same way as above. This should ensure that the aircraft was in the same state at touchdown as the previous track and the point of touchdown appears to be just about spot on.

The only thing that crossed my mind when taking control, was that i might not have got the position of the throttle levers right, so i replayed the anti-skid track again and took control just before touchdown, with the levers in the same position as the non-antiskid track, ie just above idle. It was the second antiskid track that i have attached.

From the external views, although the non-antiskid rollout did appear to be more difficult to control, the two aircraft don't appear to be too far apart on the runway, when they came to a final halt, with perhaps the non-anti-skid aircraft stopping sooner.

I might not have applied the controls at exactly the same time on both tracks, so please feel free to resume control yourselves or fly the whole thing, if you think you can get the timing of the inputs closer.

Also, if you can provide some constructive advice on my flying, particularly around the transition to on-speed flight, i'd take that gratefully.

anti skid landing.trk

non-anti skid landing.trk

I never mention you, your technique or any ambiguity as to whether or not I delay idle power until after WOW.

Looks like comprehension/terminology seems to be a factor.

I asked if you maintained constant thrust and attitude to touchdown and your response was; "I suspect this is where you are making the mistake"

I never questioned that you use (ground) idle after touchdown. I repeatedly asked if you are reducing thrust before touchdown, not if you reduce thrust to (flight) idle.

In most planes you start a partial thrust reduction before or during the flare, hence my question.