Wheel breaks F18

[Cpt Cuckoo]

Is there a known problem with the Wheel Breaks on the F-18  since the last update? They just don't work as good as they used to. They don't have that grab anymore. Taxiing on the carrier deck is dicey!

[AstonMartinDBS]

I observed no problems so far. Did you check the position of your ANTI SKID switch?

[Kang]

Wait, are you saying they work even less than they always do?

[Skysurfer]

According to some SME's the brakes are like this in real life. Just land on speed and you should be fine. I do think that the ground friction at higher speeds might be a bit too low.

Edited April 8, 2021 by Skysurfer

[Stearmandriver]

I've wondered about this too; a little 44,000lb jet should not take a mile to stop lol.  I get the sense that it's a ground friction issue in DCS in general though.  Anti-skid or not, stomping on the brakes on dry concrete should equal a violent stop, not a gradually decelerating slide like you're on ice...

[Swift.]

1 hour ago, Stearmandriver said:

I've wondered about this too; a little 44,000lb jet should not take a mile to stop lol.  I get the sense that it's a ground friction issue in DCS in general though.  Anti-skid or not, stomping on the brakes on dry concrete should equal a violent stop, not a gradually decelerating slide like you're on ice...

44,000 lbs is wayyyy over the max landing weight. And the performance charts show stopping distances as near enough to a mile when at max weight (39,000lbs). I have done some stopping tests in the past and found DCS to stop within about 200ft of the real numbers.

 

And FYI you are right, a hornet at 44,000lbs wouldnt take a mile to stop. It would probably take a fair amount more 

[Stearmandriver]

I just meant that weight of jet in general.  I've flown several jets in that weight range with similar approach speeds and all of them could be stopped in a much shorter distance... and I would expect that a plane with larger wheels like the Hornet would stop better.  

 

It's ridiculous to apply max braking on a dry runway and have the plane just sort of skate along, slowly decelerating.  That should be a violent, hanging in the harnesses kind of stop, with the anti-skid modulating as necessary to prevent a locked wheel.  What would a high-speed abort look like with that kind of anemic braking? 

 

As it stands, I can stop a 157,000lb plane in reality with normal braking, better than I can stop the little one in the sim while literally standing on the brakes.  That doesn't seem right...

 

It doesn't much matter to me as I hardly ever fly the Hornet off a runway lol... but yeah, DCS (like most other sims) has a strange ground friction model.  Even taxiing the Hornet on deck, if you stomp on the brakes there's a little slide before the plane actually stops.  On a dry anti-skid deck, at taxi speed?  That's... weird. 

Edited April 9, 2021 by Stearmandriver

[Rainmaker]

1 hour ago, Stearmandriver said:

5 hours ago, Stearmandriver said:

I've wondered about this too; a little 44,000lb jet should not take a mile to stop lol.  I get the sense that it's a ground friction issue in DCS in general though.  Anti-skid or not, stomping on the brakes on dry concrete should equal a violent stop, not a gradually decelerating slide like you're on ice...

You havent spent a whole lot of time around real fighters have you?  
 

[Tholozor]

There are gross weight restrictions in place for landings (NATOPS section 4.1.7 on Weight Limitations). Maximum allowable GW for a field landing is 39,000 lbs.

[Stearmandriver]

1 hour ago, Rainmaker said:

You havent spent a whole lot of time around real fighters have you?  
 

Around them? Yes, quite a bit.  In them, no... but a landing rollout isn't exactly a tactical maneuver.  It's a small, light jet with an average approach speed... so why would it have such an exaggerated landing rollout?  And why wouldn't it just stop immediately, when you stomp the brakes to the floor at taxi speed?  If much heavier jets do that, why not the little one? 

[Furiz]

First check Anti Skid, it should be off on the carrier and on on the runway,

second have you advanced the throttle and pulled it back once you have weight on wheels?

when you land you have to throttle up and then down again to put the engines on idle, cause they will stay at 70% if you don't do that you'll have enough thrust for to slide off the runway.

[Dunx]

Why don't you try a formation landing with an AI F/A-18C at Batumi, see if you can match their turn-off

[norman99]

 

6 hours ago, Stearmandriver said:

As it stands, I can stop a 157,000lb plane in reality with normal braking, better than I can stop the little one in the sim while literally standing on the brakes.  That doesn't seem right...

 

I'm guessing landing performance simply wasn't a concerning factor in the F/A-18s design, as it would either be operating from the carrier, or on shore from 5-10,000ft+ runways. NAS Lemore,the home base for all pacific fleet navy squadrons has 2 x 13,500ft runways, basically just for hornets.

 

Also remember, civilian aircraft have wing spoilers to immediately dump the remaining lift from the wings, significantly increasing the weight on wheels and breaking effectiveness. Not to mention thrust reverse. The hornet obviously has neither, so it's braking performance is understandably average.

 

P.S. Out of curiosity, which civil aircraft are you talking about (A320, B737)?

[Furiz]

2 hours ago, Dunx said:

Why don't you try a formation landing with an AI F/A-18C at Batumi, see if you can match their turn-off

 

AI model doesn't use same physics as player models, after they land they stop in like 100 feet, that is really unrealistic, follow an AI, I noticed they don't even use engine to move when on the ground since those nozzles don't move at all (at least with F-16AI, not sure about others), they just move like a car would.

[TimRobertsen]

10 minutes ago, Furiz said:

 

AI model doesn't use same physics as player models, after they land they stop in like 100 feet, that is really unrealistic, follow an AI, I noticed they don't even use engine to move when on the ground since those nozzles don't move at all (at least with F-16AI, not sure about others), they just move like a car would.

The AI has rear-wheel-drive, and uses a beryllium core quantum flux drive to change the aircrafts speed and direction 

[Dragon1-1]

It's counterintuitive, but the F-15 has a similar landing run to C-5 Galaxy (both just over 1km), despite the latter being much heavier. This is down to differences in design, such as thrust reversers and spoilers on the C-5, which most fighters lack. Generally, fighters land fast and don't want to get slow even in landing configuration. As such, they need to keep the nose up during the rollout (or use a braking parachute, like the Russians do). Also, DCS doesn't simulate that, but IRL you don't want to use the brakes at too high speed, because they'll overheat and become useless. They're pretty much used after you're almost stopped. 

 

If you can't stop in a short distance from taxi speed, you're rolling too fast. Larger planes have bigger gear, with more wheels, which generally improves braking performance. The Hornet only has a single wheel on each main gear, so it doesn't have much to brake with in first place.

Edited April 9, 2021 by Dragon1-1

[Stearmandriver]

5 hours ago, Furiz said:

when you land you have to throttle up and then down again to put the engines on idle, cause they will stay at 70% if you don't do that you'll have enough thrust for to slide off the runway

That I did not know; thanks for pointing it out.  If the engines don't automatically reduce to ground idle, that could definitely account for some of it. 

 

I was comparing it to similar-weight business jets, but yeah, even a 737 can stop much more aggressively than the DCS Hornet. 

 

... Like I said though, I don't think it's airplane-specific.  Even in the WWII taildraggers, the ground is far too slippery.  They'll actually slide sideways on a dry runway.  In reality, those big soft tires bite into dry pavement with no give; which is why groundloop behavior is so much more aggressively nasty on pavement than grass.  

 

Again though, pointing this out isn't intended to ridicule DCS or anything; I've yet to see any sim - even the certified level D boxes - get ground friction correct (their ground roll distances must be correct for certification, but their sideload and taxi / stopping behavior is always a little funny).

Edited April 9, 2021 by Stearmandriver

[norman99]

This might be a slight tangent, but are military aircraft, and fighters in particular, required to meet similar balanced field performance requirements as civil aircraft when getting certified? (ie the ability to both continue airborne, and stop on the remaining runway, with an engine failure at V1)

[Ahmed]

Why not, instead of everybody pitching in as an expert here, don't you guys check the landing distances in-game vs the -200 (-210 if you are lucky enough)? If they are reasonably close, I guess there is no bug. Otherwise, then there may be something to unquestionably report as a bug.

[TimRobertsen]

59 minutes ago, Ahmed said:

Why not, instead of everybody pitching in as an expert here, don't you guys check the landing distances in-game vs the -200 (-210 if you are lucky enough)? If they are reasonably close, I guess there is no bug. Otherwise, then there may be something to unquestionably report as a bug.

Discussions are fun and, it's friday 

[oldcrusty]

2 hours ago, norman99 said:

This might be a slight tangent, but are military aircraft, and fighters in particular, required to meet similar balanced field performance requirements as civil aircraft when getting certified? (ie the ability to both continue airborne, and stop on the remaining runway, with an engine failure at V1)

 

Don't know but most of them (fighters) have the tail hooks... no matter how flimsy, they can pitch that departure end cable or there might be a net hooked up to anchor chains in the overrun. It would be cool to have barriers in DCS... on some airfields of course 

[Rainmaker]

9 hours ago, Stearmandriver said:

Around them? Yes, quite a bit.  In them, no... but a landing rollout isn't exactly a tactical maneuver.  It's a small, light jet with an average approach speed... so why would it have such an exaggerated landing rollout?  And why wouldn't it just stop immediately, when you stomp the brakes to the floor at taxi speed?  If much heavier jets do that, why not the little one? 

If you are trying to compare heavy/passenger jets to fighters in terms of stopping power, you are far off the mark. Smaller brake stacks, a lot less of them, only two main tires...there’s not even a slight comparison there.  Fighters aren’t made to use up the brakes, they are very prone to generating a ton of heat, etc, etc and that’s with light landing weights. Anti-skid systems meter the brake pressure, so in a lot of cases, you get less pressure than you would with the system turned off. The system is designed around control, not max stopping power. 

[Stearmandriver]

It would seem to me that any braking system is designed around "max stopping power"... that is, after all, their sole job in most aircraft. 

 

Certainly there are limits imposed by the size and design of wheel and brake systems, but if you look at something like a CL601 (comparable landing weight) with its tiny tires (and brakes), and find that it can perform a max effort stop in a couple thousand feet... it makes ya wonder ;).

 

It appears this was discussed before, and the thread was marked "correct as is" with no explanation of the obvious disparity.  There seemed to be some confusion between normal landing length and a max effort stop; in videos you can find of Hornet landings, the pilot is not usually standing on the brakes.  It appears the Hornet perf data shows a max effort stop IS possible in a distance comparable to the Challenger in my example, but clearly in DCS it's impossible to stop in 2500ft.  This would be with anti-skid on, just standing on max brake deflection. 

 

 

[oldcrusty]

3 hours ago, Stearmandriver said:

It would seem to me that any braking system is designed around "max stopping power"... that is, after all, their sole job in most aircraft. 

 

Certainly there are limits imposed by the size and design of wheel and brake systems, but if you look at something like a CL601 (comparable landing weight) with its tiny tires (and brakes), and find that it can perform a max effort stop in a couple thousand feet... it makes ya wonder ;).

 

It appears this was discussed before, and the thread was marked "correct as is" with no explanation of the obvious disparity.  There seemed to be some confusion between normal landing length and a max effort stop; in videos you can find of Hornet landings, the pilot is not usually standing on the brakes.  It appears the Hornet perf data shows a max effort stop IS possible in a distance comparable to the Challenger in my example, but clearly in DCS it's impossible to stop in 2500ft.  This would be with anti-skid on, just standing on max brake deflection. 

 

 

I've just tested the brakes on a 3000' (roughly) runway at Haifa. 31k lbs. total weight to see if anything changed after the last update. (OP noticed some difference) I didn't notice any change between now and 3 months ago. I made a vid. at that time showing an impromptu overhead break to a full stop at Haifa. 

Right after touch down I 'double smacked' the throttles to make sure I was at ground idle, stood up on wheel brakes and extended the speedbrake. (I don't think possibility of directional control problem with speedbrakes is modeled yet). Aerobraking Hornets is not possible in current build.  No wind condition. Dry runway.

I was able to stop in little less then 3k ft.  I'll try it again w/o any loadout and just 2k lbs. of gas.

 

31k lbs.:

https://youtu.be/WzG700H0ZLs

 

Edited April 9, 2021 by Gripes323

[nighthawk2174]

I have the NFM-200 performance manual for the F18C not quite for our lot but I doubt that the braking distances would be any different.   For Full Flaps landing at 8.1° AOA at 32Klbs you should see an approach speed of just a hair under 135 knots.  For a no flare, standard atmosphere,  -4° glide slope landing there is a ground roll (full wheel brakes) of ~4500ft with a 700ft safety margin.  In DCS I am getting as stopping distance in the 4400-4600 ft region.