Use of wheel brakes after touchdown

[bluepilot76]

Have seen RL footage where the A10s opened full airbrake just prior to touchdown, maybe just at the initiation of the flare, I think the "AI" does it in DCS as well.

[Timmay]

@JCook

 

Take a look at this thread:

 

http://forums.eagle.ru/showthread.php?t=67912&highlight=Saitek+combat+rudder+problem

[FreeFall]

Yes. JCook, Invert the axis.

[Eddie]

....PS: if i understood it Airbrakes fully open only after touchdown, no wheelbrakes, no NWS until i arrived at the end of runway.

 

Engage NWS as soon as you start to loose rudder authority, but other than that, you're spot on.

 

Once you get your landing speeds right, you can easily find yourself at taxi speed and needing to apply power not much beyond the halfway point of the runway on longer runways. Especially when you are landing at a low gross weight.

 

I quite often find myself at 90 knots or less before the nose wheel hits the tarmac, even when not trying to hold the nose up.

[Panthir]

The correct braking technick varies. As far as I know, this subject is not covered in DCS manual.

Moreover, braking efficiency is related to the touch down speed.

The whole story starts when you are in final approach. There you will have to define at first which is the right approach speed, taking in account current weight and wind. A good way to define the approach speed is to configure your A/C (gear, flaps) and maintain level flight (flight path marker on the horizon) slowing down up to the speed that the Angle of Atack indicator shows the Green Circle. This is the speed that you will have to memorize and maintain when you start your final glide path. Of course there are other parameters, such as crosswind and turbulence, that you will have to take in account in order to avoid any inconvenience (stall).

Unfortunately, the DCS manual doesn't cover this subject. A nice and safe rule is the following.

Add to the ideal speed, provided by the green AoA symbol, the half of longitudinal (head)wind component and the turbulence strenght.

1st example: 20knots headwind and 123knots ideal final approach speed. The final approach speed should be 10+123=133knots

2nd example: 20-30knots headwind and 123knots ideal final approach speed. The final approach speed should be 10+10+123=143knots

2nd example: 20-25 knots from 30deg from right or left, 115knots ideal final approach speed. The final approach speed should be (cos30°*20)/2+5+115=(0,866*20)/2+120=128.66knots.

So, if you keep a final approach of 2.5-3° and you maintain the right speed then the only you will have to do is to aim for a white line touch down and then you will have to brake aerodynamically (nose high attitude) up to the speed of 80knots. Don't forget to engage Nosewheel steering and you will find out that you will need thrust to taxi up to the nearest cross section. Moreover the use of airbrakes is very effective.

 

Try it guys.

Edited January 25, 2012 by Panthir

[Inseckt]

I quite often find myself at 90 knots or less before the nose wheel hits the tarmac, even when not trying to hold the nose up.

 

Veering a bit OT here, but; I feel my NW touchdowns isn't as smooth is I would like. What is your strategy? There are several scenarios I have been applying:

 

- After main gear touchdowns (hereafter "TD"), I try to "fly" the NW down by forward stick pressure. This is usually crude and uncontrollable and the NW often slams a bit hard to the tarmac..

- After TD, I apply some backwards stick pressure and let it naturally fall to the ground by itself. This is what I normally do today, but it can still be a bit rough, especially if the AOA is in the high end on TD.

- Same as the above, but as the NW vertical speed component increases, I increase backwards stick pressure to slow it's descent. But this is hard to do and often leads to me overcompensating and taking the nose back up, often resulting in an even more rough NWTD...

 

I bet I'm just being too sensitive about it, after all, it's not like the NW is made of cardboard, I guess it's just a finesse thing...

[Panthir]

Inseckt,

 

Usually, forward stick pressure is to ensure that the nose wheel/s grabs the runway and the don't slip. In this way the NW speed generator gives to your Anti-skid system the correct speed to calculate and apply the right braking efficiency.

I assess that this subject is not simulated in DCS A-10C. If yes, then it's is essential in a slipery / wet runway.

[Frostiken]

Lol, I could image that! So you got to see them refuel? It's funny how easy they make it seem, at least thats how they made it seem everytime I have seen an a2a refuel.

 

I bet you guys had a fun time with that jet that crashed huh?

 

I'll say, 304 wasn't even that bad of a jet :(

 

Should've been 135, TBH.

[Phuz]

anti-skid off for shorter braking distances.

[effte]

anti-skid off for shorter braking distances.

 

IRL, no with an emphasis. The A/S systems of today are very good indeed. You will not be able to out-perform them. Check the -1 for A/S inop operations, IIRC it has some enlightening reading on the subject.

[Sierra99]

You would be surprised how much the brakes heat up just in normal braking. One of the first items we have to check when recovering a jet is for hot brakes.

 

ACFT tires are made so the should (key word being should) deflate themselves if they overheat but that doesn't always happen. If an A-10 main or nose tire blows and your not directly in front or rear of the tire there is a good chance you won't be alive after.

 

Ok so here's my question... Heavies have fuseable plugs that fail and deflated tires above a certain temperature if we get hot brakes... Do fighter not have these or does the size of the tire and how fast they heat up that negates their use? Or possibly the size of the brakes?

 

Just curious.

 

(Next time you're talking to a zipper suited sun gawd... Ask him when they initiate the after landing checklist. I know in the BIGGER -10, we were not to do anything until clear of the runway... A habit I tend to follow in DCS.)