Brakes are worse than in Korean era jets

I did a few braking tests in which I set up the aircraft to weight about 6 tons, accelerated to 150 km/h (80 knots) and hit the brakes. The results are quite puzzling:

F-86 Sabre stops in 230 meters.

MiG-15 stops in 370 meters.

L-39ZA stops in 380 meters.

F-5E can't stop below 400 meters mark. I made several attempts and it's usually around 430-450 meters. Tried to smash the brakes, pump them, tried threshold braking, does not matter. It's also the only aircraft that leaves black rubber marks on the runway as soon as you move the brakes axis past 30%, even though, to my knowledge, only L-39 has antiskid brakes.

Something is seriously wrong. Especially considering that 6 tons for the other aircraft is near or above MTOW, while fully loaded F-5 could weight 11 tons. :huh:

EDIT: look below for comparison with real world tables: https://forums.eagle.ru/showpost.php?p=3218618&postcount=4

That's why the F-5 is equipped with a drag chute.

Yes brakes on F-5 are weak and they have no anti-skid, it was discussed a lot of times. That's exactly why there is a chute and you should use it, it's there for a reason.

I live near a base where Mig29s are stationed, they can for sure brake and come to stop using only brakes after they land because runway is pretty long, yet they always use the chute. One reason is that it is easier to repack the chute than it is to replace the worn out brake pads.

Use the chute.

:doh: Guys, instead of going into full denial mode, read what I wrote and think a bit:

1. You have four aircraft, all at the same weight of six tons. Two subsonic fighters designed in the 40's. One trainer jet that is heavily overwheight at 6 tons and was not designed for such payload. And one supersonic jet designed 15 years later that could weight up to 11 tons at takeoff. F-5 brakes could be weak, but not THAT weak.

2. F-5 is the only aircraft that actually skids on the runway in DCS. Even though MiG-15 and F-86 don't have antiskid system, you can hit the brakes to 100% and they will nicely slow down without skidding, and at much shorter distance. Maybe the F-5 is fine and the other airplanes have overperforming brakes, but clearly this is a huge inconsistency.

3. The chute is not mandatory for landing in the F-5, read the real manual. You have tables for landing with and without chute. The difference in ground roll, while considerable, is not as we have now in DCS.

I did another tests in DCS to compare brake performance with the tables from the manual here: http://www.avialogs.com/index.php/en/aircraft/usa/northrop/f-5tigerii/t-o-1f-5e-1-f-5e-flight-manual.html

I loaded the aircraft to 15'000 lbs, accelerated to 150 knots, which is the touchdown speed at that weight according to the table A7-6 and measured the braking distance with and without chute. I needed 5000 feet to stop without chute and only 2000 feet to stop with brake chute. According to the tables on pages A7-7 and A7-8 of that manual, the ground roll distance for that weight at 20 degrees and 1000 ft pressure altitude (I tested at Mineralnye Vody) should be roughly 4400 ft without chute and 3000 ft with chute. And that I guess is the total ground roll distance from touchdown point to the stop, not from brake/parachute activation, which happens only after the front wheel is on the ground. So you need to add a couple hundred feet to my results to compare them with the manual.

Either way, it clearly shows, that the wheelbrakes in the F-5 are underperforming, while the parachute is overperforming compared to real data. And the F-5 brakes in DCS are PITA to use, you move the brake axis to 30% and start skidding.

:doh: Guys, instead of going into full denial mode, read what I wrote and think a bit:

Well, you might not believe how many threads are beeing created on these forums all the time where people complain that something is unrealistic, just because it's not like they want it to be ;)

1. You have four aircraft, all at the same weight of six tons. Two subsonic fighters designed in the 40's. One trainer jet that is heavily overwheight at 6 tons and was not designed for such payload. And one supersonic jet designed 15 years later that could weight up to 11 tons at takeoff. F-5 brakes could be weak, but not THAT weak.

Why not? It has a chute, so it doesn't need such strong brakes.

2. F-5 is the only aircraft that actually skids on the runway in DCS. Even though MiG-15 and F-86 don't have antiskid system, you can hit the brakes to 100% and they will nicely slow down without skidding, and at much shorter distance. Maybe the F-5 is fine and the other airplanes have overperforming brakes, but clearly this is a huge inconsistency.

I agree here. It seems indeed inconsistent.

3. The chute is not mandatory for landing in the F-5, read the real manual. You have tables for landing with and without chute. The difference in ground roll, while considerable, is not as we have now in DCS.

Well, the chute not mandatory to land in DCS as well. The runways are long enough to land by just using the brakes without a chute.

I did another tests in DCS to compare brake performance with the tables from the manual here: http://www.avialogs.com/index.php/en/aircraft/usa/northrop/f-5tigerii/t-o-1f-5e-1-f-5e-flight-manual.html

 

I loaded the aircraft to 15'000 lbs, accelerated to 150 knots, which is the touchdown speed at that weight according to the table A7-6 and measured the braking distance with and without chute. I needed 5000 feet to stop without chute and only 2000 feet to stop with brake chute. According to the tables on pages A7-7 and A7-8 of that manual, the ground roll distance for that weight at 20 degrees and 1000 ft pressure altitude (I tested at Mineralnye Vody) should be roughly 4400 ft without chute and 3000 ft with chute. And that I guess is the total ground roll distance from touchdown point to the stop, not from brake/parachute activation, which happens only after the front wheel is on the ground. So you need to add a couple hundred feet to my results to compare them with the manual.

 

Either way, it clearly shows, that the wheelbrakes in the F-5 are underperforming, while the parachute is overperforming compared to real data. And the F-5 brakes in DCS are PITA to use, you move the brake axis to 30% and start skidding.

Now we are talking. What was missing so far were some real data to make actual comparisons and draw conclusions from. ;)

I have not tested it myself, but judging from your test results compared to the tables the brake performance (with and without chute) seems indeed to be off by quite a bit.

I agree the brakes\wheels seems overly susceptible to skid on a dry runway. AFAIK the brakes should be effective and safe to use below 120 kt and incorrect use, result in overheating and excessive wear, not wheel skids.

My braking technique in DCS at correct weight/touchdown speed is

• Nose wheel DOWN
  
• Air brakes OUT
  
• Stick FORWARD
  
• Rapid taps on Wheel brake (as I don't have floor space for pedals)
  

Aerodynamic braking is weak and contact friction low in DCS but seem to be a general issue rather than module specific.

The M-2000C handles the issue (perhaps increasing rolling friction ?) but it's idle taxi roll requires more power than described by pilots. The L-39 takes the middle ground, so might be a better ref. for a BST compromise.

@some1: Do you use a key or an axis for braking?

Why not? It has a chute, so it doesn't need such strong brakes.

There's 100% difference in the stopping distance between F-5 and F-86 in DCS. Hard to belive it's realistic.

The aircraft still has to stop in a reasonably safe way in case of chute malfunction, even during takeoff at heavy weight. You have charts for that in the real manual too. (A2-25).

Besides, parachutes are not a magic devices, they don't give you much stopping power at lower speeds. You still need powerful brakes for that.

@some1: Don you use a key or an axis for braking?

Axis.

There's 100% difference in the stopping distance between F-5 and F-86 in DCS. Hard to belive it's realistic.

 

The aircraft still has to stop in a reasonably safe way in case of chute malfunction, even during takeoff at heavy weight. You have charts for that in the real manual too. (A2-25).

Besides, parachutes are not a magic devices, they don't give you much stopping power at lower speeds. You still need powerful brakes for that.

The F-86 is not equipped with a brake chute, so I don't see why it shouldn't be realistic just because of that. But then you posted those charts that convinced me that the brake performance is indeed not quiet realistic.

Axis.

Alright, I was just curious. :)

Solution: speed brakes, chute as soon as the nosewheel touches, full aft stick after touch-down, and gentle, steady pressure on the wheel brakes. You'll make the first turn-off at most fields 99% of the time.

The issue is, we don't want a gameplay solution for airquake, we want the aircraft to function in game as close to the real thing as possible. ;)

It seems like the brakes are not functioning realistically.

It seems like the brakes are not functioning realistically.

Yep, SEEMS, with the only thing missing being actual evidence of their underperformance :music_whistling:

I'm not saying they can't be at fault, mind you. But in order to get stuff changed in DCS, one has to present tangible evidence supporting the change.

Yep, SEEMS, with the only thing missing being actual evidence of their underperformance :music_whistling:

 

I'm not saying they can't be at fault, mind you. But in order to get stuff changed in DCS, one has to present tangible evidence supporting the change.

some1 did present evidence on the previous page, or not?

some1 did present evidence on the previous page, or not?

Hmmm... seems I missed that the first time around. My apologies. Well, let's see what the devs say about it.

I''m not a fan of the brakes either. The skidding feels like scripted, not modelled.

does this pass the integrity check?

Doesn't feel 'scripted' to me and I've solved this problem by reducing the brake strenght on each wheel to 35%.

That way I can apply full brakes and the F-5 wheels don't lock up.

 

dcs>mods>aircraft>f-5E>FM>config.lua

 

Change the left & right wheel_brake_moment_max from 5500 to 2000.

You've solved the problem of brakes taking too long to stop the aircraft by reducing the brake pressure...?

You've solved the problem of brakes taking too long to stop the aircraft by reducing the brake pressure...?

If that prevents the wheels from locking up it's logical isn't it?

Are the brakes able to hold the aircraft at engine spool up before takeoff now?