End of the runway

[ENO]

I'm not sure if it's that people are "afraid" of using them as much as it is that they don't work very well... so they're certainly not something that can be used reliably.

 

I was interested in the demo showing the benefit of not using the anti skid- at least as it was demonstrated earlier in this thread.

 

So... did we ever decide if anti skid turned off would result in more realistic function of the wheel brakes?

[BlueRidgeDx]

Yes, I tested it thoroughly last week and it is confirmed that anti-skid is the culprit.

 

Executing a Minimum Run landing with immediate maximum performance braking results in a stopping distance that is longer than a normal landing followed by three seconds of coasting followed by braking that doesn't invoke anti-skid. An extensive bug report has been filed. Viper also made a similar report, errrr, a while ago...

 

I did not attempt any landings with the anti-skid off, since I was careful not to brake hard enough to activate the anti-skid feature.

 

Nonetheless, I keep hearing people say that they can't stop on runway and the only explanation is that they're just not using the proper (real) technique. Despite the fact that the landing distances are nearly double what they should be, they're still short enough to land on any hard-surface runway on the map. You just can't come smoking in, land at midfield, and then aerobrake until you run out of runway.

 

Fly the approach with the speedbrakes at 40%. Get in on the ground in the first 1,000ft of runway. Get the nose wheel down and the speedbrakes to 100% without delay. At 100 knots, start gentle braking.

 

Using that technique there isn't a "real" runway you can't stop on, regardless of weight. I purposely exclude the "X" runways near batumi, and the crop-duster field near Kutaisi...

[Echo38]

Fly the approach with the speedbrakes at 40%. Get in on the ground in the first 1,000ft of runway. Get the nose wheel down and the speedbrakes to 100% without delay.

At 100 knots, start gentle braking. Using that technique there isn't a "real" runway you can't stop on, regardless of weight.

 

Blue, can you do that if you have the throttles at idle for the entire approach? Or does stopping without wheelbrakes require the power & airbrake combination while flaring? (Excepting a "carrier landing"--as I mentioned in one of my posts, I can stop without using wheelbrakes, but only if I bring her down very hard like an F/A-18.)

[159th_Viper]

Nonetheless, I keep hearing people say that they can't stop on runway...

 

Echo mentioned that he cannot coast to a stop without the use of wheelbrakes and I share that sentiment. Yes, the plane will stop with a minor tap or two of the brakes, but if left to coast then there's no way it's stopping if I fly a green doughnut till touchdown, even with one engine dead. No doubt a wonky technique, but I cannot see how to get it to stop - advice would be appreciated :)

 

1.2.0: Kutaisi coast.trk

[Echo38]

For clarification, when I'm talking about being unable to "stop" without wheelbrake, I really mean that I'm unable* to slow down enough to safely turn off onto the taxiway at the end of the runway. Since I can't even do that, a full stop on the runway is the farthest thing from my mind. ; )

 

As for why I'm slamming my head against this no-wheelbrakes thing, well, it's actually a sort of self-challenge which I started back when Lefty Gardner was still alive, when I read that he never used brakes on White Lightnin' except for holding her for the run-up. I know, I know, an A-10's no P-38 ...

 

*Again, barring carrier-style landings.

Edited September 13, 2012 by Echo38

[159th_Viper]

For clarification, when I'm talking about being unable to "stop" without wheelbrake, I really mean that I'm unable* to slow down enough to safely turn off onto the taxiway at the end of the runway. Since I can't even do that, a full stop on the runway is the farthest thing from my mind.......

 

Ooohhh.......OK then - apologies for the misunderstanding. I thought you meant coasting to a dead-stop on the runway :)

 

Could you post a track for us to analyse?

[Echo38]

Okay, here we go. No wheelbrake at all was used at any point in the track. I touched down with surely no more than 10% of the runway wasted, and immediately deployed airbrakes and got the nosewheel down. But I still nearly blew a tire (and almost dragged a wing) when I turned off onto the taxiway, because I was going about three times as fast as I'd like to be at that point.

 

I'm aware I could be cutting a few hundred feet off by coming in under power with airbrakes out, but I don't want to do this for several reasons. Beyond doing that, I can't think of anything else I could be doing significantly better (regarding the slowing-down-without-wheelbrake). Sure, with a lot more practice, I'll maybe eventually be able to come down a few more yards closer to the beginning of the runway. But, aside from that, I'm stumped.

Dead-Sticking & Bad Taxi.zip

[BlueRidgeDx]

Cant watch the track at the moment, but no, if you're able to fly the whole approach at idle, then you're flying too steep of an approach. The approach should be flown with power, and with the speedbrakes at 40%. The runway threshold should be right between the 0 and -5 degree pitch ladder bars, and the TVV should be placed right on the beginning of the pavement.

 

As you descend through 30 feet, you should smoothly fly the TVV up to the far end of the runway while bringing the power to idle. The approach speed depends on weight - 130 knots plus 2 knots for every 1,000lb over 30,000lb. Landing speed is 10 knots slower than approach speed. You should lose those 10 knots during the flare.

 

At no point should you make a navy-style carrier landing.

 

There actually is a case where you do make a navy-style landing, but it's not relevant here and I don't want to muddy the waters any more than they already are.

[159th_Viper]

Okay, here we go. No wheelbrake at all was used at any point in the track. I touched down with surely no more than 10% of the runway wasted, and immediately deployed airbrakes and got the nosewheel down. But I still nearly blew a tire (and almost dragged a wing) when I turned off onto the taxiway, because I was going about three times as fast as I'd like to be at that point.

 

I'm aware I could be cutting a few hundred feet off by coming in under power with airbrakes out, but I don't want to do this for several reasons. Beyond doing that, I can't think of anything else I could be doing significantly better (regarding the slowing-down-without-wheelbrake). Sure, with a lot more practice, I'll maybe eventually be able to come down a few more yards closer to the beginning of the runway. But, aside from that, I'm stumped.

 

No, apart from choosing one of the shortest runways in Georgia (Kobuleti, Senaki being another one) and the supremely unorthodox approach, you're doing everything pretty much spot-on.......There's just no way the A-10 is gonna stop sufficiently under it's own steam to safely depart the RW - Some use of wheelbrake is essential for what you propose. Be glad you're not attempting that at Gelendzhik where you have a mere 5800 feet to work with :megalol:

Edited September 13, 2012 by 159th_Viper

[Corrigan]

While the approach was one of the strangest things I've ever seen, the final and touchdown look OK to me. As you say, you really needed wheel brakes.

 

EDIT: as above.

[Yskonyn]

Cant watch the track at the moment, but no, if you're able to fly the whole approach at idle, then you're flying too steep of an approach. The approach should be flown with power, and with the speedbrakes at 40%. The runway threshold should be right between the 0 and -5 degree pitch ladder bars, and the TVV should be placed right on the beginning of the pavement.

 

As you descend through 30 feet, you should smoothly fly the TVV up to the far end of the runway while bringing the power to idle. The approach speed depends on weight - 130 knots plus 2 knots for every 1,000lb over 30,000lb. Landing speed is 10 knots slower than approach speed. You should lose those 10 knots during the flare.

 

At no point should you make a navy-style carrier landing.

 

There actually is a case where you do make a navy-style landing, but it's not relevant here and I don't want to muddy the waters any more than they already are.

 

+1

If you are used to prop sims, then it might be a tip to point out that you should not close the throttle before the flare.

You should also be gentle with throttle movement and not slam it shut.

When flaring, close the throttle gently and pull op the nose gently to decrease the vertical speed.

Jets are 'flown' to the deck more than props. :joystick: But gentle touchdowns are more than possible while even getting it to stop in time in-sim. ;)

:pilotfly:

[159th_Viper]

Was curious and came up with the following:

 

To touch down, coast and reach a decent taxi-speed without utilizing wheel brakes, in the configuration you tested (90% Fuel, no ordinance, GW of approx 36500 pounds on landing), you need the following distances:

 

*30 Knots - 9 720 feet of runway

 

20 knots - 11 540 feet of runway

 

10 knots - 12 760 feet of runway

 

*(Assuming of course that the F2 info bar readout is in knots)

 

Dead-Stick.trk

[GGTharos]

But this is probably not a very realistic configuration. I would expect a landing weight of 30000-32000 lbs.

[159th_Viper]

But this is probably not a very realistic configuration. I would expect a landing weight of 30000-32000 lbs.

 

Yeah, quite so. At those numbers (31 000lbs), as follows:

 

 

30 Knots - 7 900 feet of runway

 

20 knots - 9 720 feet of runway

 

10 knots - 10 200 feet of runway

[GGTharos]

I don't have a -1 handy ... any idea on how that meshes with the -1 landing roll data? :D

[159th_Viper]

No idea :)

 

The -1 accounts for braking in the roll-out distances, no? That being the case, cannot then compare to the above as no brakes are utilized in my numbers.

 

As an aside, what is the standard of braking to be employed when comparing to the -1 data? Foot through the floorboards? :D

[BIGNEWY]

You guys all have OCD

 

Just put the damn wheel breaks on !!

 

:)

[BlueRidgeDx]

As I explained in the other thread regarding landings, you need to stop aerobraking; it doesn't work in the A-10. Get the nose on the ground and with full speedbrakes, the airplane will coast to a stop without wheel brakes on an 8,000 ft runway.

 

Okay, so this is statement is false. That s what I get for pulling a number out of my ass and trying to prove an unnecessary point.

 

My intent was to debunk the oft cited notion that it was not possible to stop the aircraft on the runway using normal techniques.

 

I ruined the entire premise by myself suggesting an abnormal technique; to coast to a stop on the runway without using the brakes. This is never done in the real world. As airspeed decreases, the effectivenes of aerodynamic surfaces decreases. Thus the speedbrakes are most effective early in the rollout. Decelerating through 80-100 knots, only light braking is required to reach taxi speed very quickly.

 

I just flew two approaches at Kutaisi, and went off the end at 29 knots. 20 knots is taxi speed. So if I can very nearly reach taxi speed on a 7,600ft runway without brakes, then clearly there should be no reason to go off the end if you're using anything close to the proper techniqe.

 

What I should have said is "practically", as in, "Get the nose on the ground and with full speedbrakes, the airplane will practically coast to a stop without wheel brakes on an 8,000 ft runway."

 

My apologies for being imprecise.

[Tailgate]

Bottom line ... Brakes are good, they are there for a purpose. :)

[Echo38]

Lesson learned--time to start applying wheelbrake. Hey, how to best go easy on them? Leave 'em alone until speed's low, then smoothly apply half brake? Or apply lighter pressure while speed's high, and increase as speed drops? I don't want to be learning a bad habit which would, in a real aircraft, be excessively wearing on the brakes.

[GGTharos]

The real answer is that it depends. If you have the time and inclination, wait for your speed to drop to 50kt or less before applying, then there's almost no way to overheat'em enough to blow up the tyres (single application) - IIRC.

[ENO]

8 pages on brakes- but it seems to be shifting from "whether to use wheel brakes" versus "whether to use wheel brakes with the anti-skid disengaged."

 

My understanding from what I've read is a combination of all of these things- but that the anti-skid features seems to be the element of the sim that is contributing to the "wet surface" runway effect.

[PeterP]

Brakes of the A-10 have been discussed to death already before in this thread:

Landing rollout

And you can read between the lines of some comments that the modelling can use some fine-tuning and that the developers are aware of it.

[ENO]

A thread in march and one in January isn't exactly beating it to death but I get your drift.

[Yskonyn]

Okay, so this is statement is false. That s what I get for pulling a number out of my ass and trying to prove an unnecessary point.

 

My intent was to debunk the oft cited notion that it was not possible to stop the aircraft on the runway using normal techniques.

 

I ruined the entire premise by myself suggesting an abnormal technique; to coast to a stop on the runway without using the brakes. This is never done in the real world. As airspeed decreases, the effectivenes of aerodynamic surfaces decreases. Thus the speedbrakes are most effective early in the rollout. Decelerating through 80-100 knots, only light braking is required to reach taxi speed very quickly.

 

I just flew two approaches at Kutaisi, and went off the end at 29 knots. 20 knots is taxi speed. So if I can very nearly reach taxi speed on a 7,600ft runway without brakes, then clearly there should be no reason to go off the end if you're using anything close to the proper techniqe.

 

What I should have said is "practically", as in, "Get the nose on the ground and with full speedbrakes, the airplane will practically coast to a stop without wheel brakes on an 8,000 ft runway."

 

My apologies for being imprecise.

 

I would even dare say the Speedbrakes have limited effect on braking distance at all.

They are called speedbrakes for their aerodynamic function in flight. But, as pointed out above, they do nothing much with only a small airflow.

They function more as lift-dumpers, to safeguard weight on wheels to aid proper braking.

 

Regarding braking technique, there is nothing prescribed in the -1.

Funny detail, however, is that contrary to belief in the thread above, aerodynamic braking is mentioned as a viable means of braking when runway length isn't a factor. (2-21, AFTER LANDING).

There is also a paragraph dedicated to minimum run landings.

Edited September 15, 2012 by Yskonyn