Landing: To airbrake or to not to airbrake?

[ekg]

What is the general convention for airbrakes during landing? As of late I've been using them more and using more thrust to compensate for the drag. I find that it gives be a bit more control over speed. However I'm not sure if that's the "correct" way to do it. Any definitive guide for this?

[Sryan]

would help if you specified what planes you flew. On the MiG21 landing with brakes can quickly get suicidal, that delta just gotta fast. The A10 is a lot easier to land with brakes, you can keep it under control even when very slow. On something like the su25 it feels like it hardly even matters, it seems they are more intended as divebrakes when doing an attack and don't do much at landing speeds.

 

If you do a proper approach and follow the glidescope you shouldn't really need the brakes on any plane.

[Apache600]

I would say yes, keep doing it.

In real life, say on an airliner, the "brakes" that are deployed after landings are actually "spoilers" (the speed brakes also deploy, on the inner most side of the wing closest to the fuselage, but are 1/3 of the surface area compared to the spoilers). Their purpose is to destroy the lift created on the wing, and help transfer the weight of the aircraft onto its wheels. Thus making the wheel braking far more effective. The air brakes on fighters are a little different, they don't have "spoilers" but they still acts in much the same way after landing. They create a huge amount of drag, which helps to overcome what lift may have still been on the wing, and transfers the weight to the wheels.

After landing, you can also try and keep the nose up in the air (make sure the main wheels are firmly planted on the ground first) This will act as aerodynamic braking as well.

[ekg]

would help if you specified what planes you flew. On the MiG21 landing with brakes can quickly get suicidal, that delta just gotta fast. The A10 is a lot easier to land with brakes, you can keep it under control even when very slow. On something like the su25 it feels like it hardly even matters, it seems they are more intended as divebrakes when doing an attack and don't do much at landing speeds.

 

If you do a proper approach and follow the glidescope you shouldn't really need the brakes on any plane.

 

Right now I fly the Su-25 and Su-27. I follow the proper glidescope as indicated on the instruments. However I find the airbrake and increased thrust (75-85 % RPM) gives the plane a bit more "stability" in terms of glideslope and speed. The moment I touch down I set the thrust to 0 and deploy the parachute. When I land my vertical velocity is 3m/s or less.

[Apache600]

oh, during the landing phase you mean. Having the proper flaps, airspeed, and glidepath should negate the need of the airbrake.

[Retu81]

Another point for using airbrakes on landing: you can close the brakes faster than the engine(s) can spool up. So if you need to abort, just close the brakes.

[Ironhand]

What is the general convention for airbrakes during landing? As of late I've been using them more and using more thrust to compensate for the drag. I find that it gives be a bit more control over speed. However I'm not sure if that's the "correct" way to do it. Any definitive guide for this?

Haven't been in the Su-25 in quite a long time. So I'm only going to address the Su-27. There is nothing in the Su-27 pilot's manual (or the part of it that I have access to, anyway) that recommends the use of the speed brake as part of the landing procedure. It addresses the proper timing and use of flaps, extension of landing gear, etc. but the speed brake is never mentioned. As a matter of practice, I normally don't use it myself as a part of the landing procedure unless I'm carrying excess speed that I need to drop. As soon as I've adjusted my speed, I pull it in and adjust power to maintain a gradually diminishing airspeed until I cross the threshold at about 260-270 k/hr depending on weight.

 

According to the manual, you should be crossing the outer marker between 310-320 k/hr at an altitude of 200 m and slowly reducing speed to cross the inner marker between 290-300 at a height of roughly 60 m.

Edited November 5, 2015 by Ironhand

[Rongor]

Look up the desired landing speed. Always aim for that landing speed in your landing attempts. Use the speed brake only if you notice your speed being too high and if you think the use of the speed brake will slow you down enough to be able to maintain your approach with the correct landing speed.

In all other cases- especially if your speed is fine - don't use the speed brake.

In case of an emergency, failed approach, anything, you wanna accelerate real quick for a go around, to assure enough speed to climb up into safety with a safe climb speed. You don't want to have to pay attention to the need of retracting the speed brakes first. So the standard setting should be speed brakes off.

After touch down and your decision that no go around will take place, you of course can use the speed brake to support decreasing of velocity.

[Exorcet]

In case of an emergency, failed approach, anything, you wanna accelerate real quick for a go around, to assure enough speed to climb up into safety with a safe climb speed. You don't want to have to pay attention to the need of retracting the speed brakes first. So the standard setting should be speed brakes off.

After touch down and your decision that no go around will take place, you of course can use the speed brake to support decreasing of velocity.

 

Depending on how fast your engines spool, brakes out might be the faster way out of trouble

 

For the Su-27, it probably doesn't really matter, though I don't know definitively what is the most authentic way to land. I've seen F-15's both use the brake and keep it retracted. I'd assume the Su-27 is similarly flexible.

[ShuRugal]

Ordinarily, I would say land without speedbrake: do what Rongor said and look up the correct approach profile for your chosen bird, and fly it.

 

However, I just made a landing which required the use of my brakes: Over the final-turn point at 13km altitude, diving down into the glideslope at ~60 degrees. kept throttle on idle and used speedbrake the whole way. Final touchdown speed (SU-27) was ~280 kph, sink rate <1m/s.

 

However, this was a severely non-standard approach and would probably get your wings taken away if attempted IRL outside the environment of a planned demo at an airshow. My speed over the inner marker was 500 kph, and i didn't extend gear and flaps until i crossed the beacon because i was too hot (i know damage is not modeled yet, but i don't want to form bad habits for when it is).

 

For standard landing approaches? don't fool with the brakes, just fly your approach with enough precision and forethought that you don't need them.

[ekg]

Seems like the general consensus is to not use airbrakes. Do you deploy them on touch down?

[Shmick]

I was chatting to AussieGhost recently about this (when attempting a carrier landing in an F-15C :-P) and he made what I thought was the good point that on the F-15 and the Su-27 for example, the speedbrake's also going to exert a downward force, opposing your flaps to some degree.

 

That'll mean that for an on-slope approach, if you're trying to maintain a given AoA, you'll need to have relatively higher speed to maintain it with the speedbrakes out.

Edited November 5, 2015 by Shmick

[boomerang10]

Whether or not you have them out depends on everything from platform right down to pilot preference.

 

The idea behind landing with them out is that the extra drag requires you to fly the approach at a higher power setting and keep the engine spooled up away from the idle stops. Thus, if you do have to execute a go around there is less spool-up time required for the engine to develop full power.

 

Personally, I fly the approach with them out with the F-15 and A-10, for example, but not the MiG-21. It should be noted that some aircraft, like the A-10, require weight on wheels to achieve full extension of the speedbrakes.

[leadlag]

Landing with air brakes extended is a generally a safer option especially in strong winds as the wind gradient can be very severe and you have more control of the decent with them extended and engines throttled up. In fact a steeper approach needs to be flown in certain conditions.

 

Conditions dictate but generally land with is better.

[Nealius]

I copy what I see in videos. For F-16 that's airbrakes out. A-10 it's airbrakes partially out, then out all the way once the wheels touch the pavement.

[gospadin]

I copy what I see in videos. For F-16 that's airbrakes out. A-10 it's airbrakes partially out, then out all the way once the wheels touch the pavement.

 

Yup. ~30% airbrakes on the A-10, since it's much faster to retract than bring the engines up from idle.

[Frostie]

Airbrake out for more control and shorter landings, ideal for short runways.

[ekg]

Looking at Su27 landing videos it's about 50/50 for airbrakes. I wish they were a bit better since it's hard to tell if they just apply airbrake right before touchdown or if it's on during the glide down to the runway.

[OnlyforDCS]

I use them with the Su27, and F15C. Like many others have stated, they provide more control on final and help get my speed down to manageable levels before deploying gear/flaps.

[112th_Rossi]

I use airbrakes to bring my speed down for the approach then apply as appropriate. They are tool to use just like anything else.

[BSS_Sniper]

A lot of you are saying to use it if you feel like it...

 

The only answer is, it depends. It depends if that particular aircraft procedures says you should use it. Some will say don't use below a certain altitude, some will say to use, such as the A10 and F86 because it takes time to spool up the engine and using the brakes keeps the engines spooled up.

 

You need to look up the procedure for each specific aircraft and follow it. That's the only real answer to this.

[Pineapple Pete]

The F-86 and the F-15 are the only jets I fly in DCS. Only in the F-86 is having the air brakes deployed for landing a standard procedure. This is because the engine in the F-86 is slow to spool up to go around thrust should you need it. As some have said in response to you it is quicker and therefore safer, to have higher thrust on approach (to maintain propped approach speed) and then just retract the airbrakes while increasing thrust if you need to go around.

I am not studied up on the vintage Migs so I cannot speak about them.

[Bushmanni]

The "correct" procedure also depends on the operator. For example, JASDF F-15 pilots have airbrake usually open during landing while USAF has it closed.

[Nedum]

The F-86 and the F-15 are the only jets I fly in DCS. Only in the F-86 is having the air brakes deployed for landing a standard procedure. This is because the engine in the F-86 is slow to spool up to go around thrust should you need it. As some have said in response to you it is quicker and therefore safer, to have higher thrust on approach (to maintain propped approach speed) and then just retract the airbrakes while increasing thrust if you need to go around.

I am not studied up on the vintage Migs so I cannot speak about them.

 

And before 1.5 this was the reason for me to use the air brake during landing with the Su27. The spool up time was really bad and the reaction on the throttle work was more like "on and off".

But I think these extra "speed" you can hold back with the use of the air brake isn't that bad at all if you need to touch and go. ;)

[Luzifer]

Another thing is it's not just that with brakes you don't have to spool up the engines from (near) idle in case of a go-around, for the same reason the engines are also much more responsive on approach when you need them to adjust your glide path.

 

As has been said, it really depends on the plane's design, what is normal for one isn't for another. For example, don't think that airliners don't use air braking since most leave the spoilers in until touch down — the flaps are extended beyond the point where they increase lift and decrease stall speed and instead only generate massive amounts of additional drag.