AAR under wake turbulence

Thanks TacKen! That does help quite a bit.. so most of the actual turbulence emanates outward along the wingtips then?

From you are saying, it seems what I've seen in wake turb during refueling may be a touch too much. A small burble with some minor jetwash. Is that a good summary?

Actually, wake turbulence can trail pretty far behind an aircraft and give some medium chop along with rolling and pitching moments when you hit it. Occasionally in congested airspace, you would hit some wake turbies in clear air on a sunny day. You would hit it, feel jostling along with some thunderous buffeting sounds. Not enough to kick off the autopilot, but enough to jostle and cause some roll or pitching. You would look around and there would not be a plane in sight. Wake turbulence falls at about 500 feet per minute. It all depends on the type aircraft and how heavy it is.

 

 

 

In typical fashion, min separation timing is 3 minutes when departing behind a heavy type aircraft. After the heavy departs, the following aircraft is held for 3 minutes before allowed to depart from the same runway. Even when landing or following a heavy aircraft at same altitude or less than a 1000ft, there is spacing. For a heavy following another heavy, it's a 4 mile separation. For a light aircraft following a heavy, its a 6 mile separation. This goes to show that wake turbulence trails at a long distance and has tremendous effect. I flew heavies for a long time. This is the reason that "heavy" is attached to the call sign of heavy type aircraft, reminds everyone of the wake turbulence rules for that aircraft.

 

 

 

Once during a formation departure in a KC10, we departed Al Udeid following another KC10 just to get formation beans knocked out since our departure times were so close. I departed 30 minutes early to get it done. It was night and we were at the non standard mile in trail. He was in the clouds so I lost him in the turn as I was at 350kts trying to rejoin. We had him on TCAS and was using the weather radar to skin paint him. While trying to move upwind of his turn and cut him off, I passed through his wake in the clouds at a mile. The jet snapped to 60 degrees left and it was all I could input with right yoke to stop the roll and get her rolling to the right. It caught me off guard because based on the winds on my nav display, I should have been upwind.

 

 

Since the wake turbulence falls so slow, you are never in it during refueling(heavy perspective). You approach the tanker at the bottom of the block a thousand feet below. Once the tanker and your ready light lines up, you start the reverse ILS up to the tanker and you are out of it. You do get the down wash from the wing and fuselage and there is a burble that you power through initially to reach the contact position. You will also feel the tanker's engines push you towards center if you got out there far enough. The 135 has a small envelope, so its easy to get pushed by their engines when off center versus the wide area on a 10.

 

 

As for the wing drogue pods, the turbulence funnel at the wing tips are narrow and stretched out at refueling speeds. Wake turbulence is a big factor when a plane is heavy, low and slow. A receiver should be able to descend from the wing position and drift back behind the drogue and approach without issue. I may have, a few times joined the boom to watch drogue refueling from our wing pods. I never seen a fighter bothered by our wake during position changes and refueling. When you think about it, the drogue is inside of and below the wake turbulence. That's why its stable when deployed. In the KC10, there was a warning about extending the slats with a wing pod drogue deployed. The turbulence from the slats would cause the drogue to violently spin and possibly make contact with the wing/slats(it happened before). If a wing pod drogue was stuck out and you could not jettison the hose, you had to do a no slats with flaps landing.

Amazing stuff. This is so packed with detailed and interesting information from a practical experience.

That excerpt from your flight experience makes for a great read.

So I guess I have to correct my assumption on effect of wake turbulence from a far distance.

I am curious, does the wind direction and speed data on the aircraft change to indicate this upsetting turbulence?

It is safe to assume the wind measuring instruments would reflect the sudden change and can be use as a warning that an aircraft is entering the wake turbulence zone of a leading aircraft.

Thanks TacKen! That does help quite a bit.. so most of the actual turbulence emanates outward along the wingtips then?

From you are saying, it seems what I've seen in wake turb during refueling may be a touch too much. A small burble with some minor jetwash. Is that a good summary?

Yes, It spreads outward and can be 900ft below the aircraft 5 miles behind.That's why when you are close in and beneath the tanker, you tend to be out of it. It's more pronounced aft of the aircraft. It's like dragging tornadoes from your wingtips.

Not having a fighter's perspective and only seeing Navy fighters refuel on the my wing pods, that would be my guess. Even large aircraft, C-5/747 behind the tanker are not in our wake turbulence. But you do notice the down wash onto your aircraft. It comes in the form of having to add nose up trim as you close in from the pre-contact position. The plane tends to want to descend as you get close and forward movement slows. When I flew C-141s, we had to add nose down trim because the down wash pushed on the T-tail raising the nose as you closed in. The burble manifested itself as sound changes and audible air on your air-frame and the tendency of your forward movement being slowed or stopped. As you entered it, you added a little power, but had to take it out as you pierced the burble. The amazing thing is showing a new guy how you can move forward or aft of the tanker without touching the throttles while on the boom. You need to move forward, you climb a little in the envelope streamlining the formation and the jet starts to move forward. You in a little tight and need to move aft, you move down a little in the envelope dirtying the formation and the jet starts to move aft. Go back to the center as you reach your desired position. This was good for confidence building for new guys who jockeyed the throttles alot on the boom.

Much appreciation for this Tacken.

Amazing stuff. This is so packed with detailed and interesting information from a practical experience.

 

That excerpt from your flight experience makes for a great read.

 

So I guess I have to correct my assumption on effect of wake turbulence from a far distance.

 

I am curious, does the wind direction and speed data on the aircraft change to indicate this upsetting turbulence?

It is safe to assume the wind measuring instruments would reflect the sudden change and can be use as a warning that an aircraft is entering the wake turbulence zone of a leading aircraft.

That would be awesome and would give you the ability to detect all kinds of turbulence to include that pesky clear air turbulence. Unfortunately, this is driven by the way the aircraft detects wind direction and speed. The system collects aircraft track and ground speed data from the internal inertia systems(INS/IRS). It compares this data with the aircraft's current heading and true airspeed(TAS). The difference between the collected data allows the system to give wind direction and speed. The information displayed is the wind that is acting on the aircraft at this moment. What we do in formation is as long as you have the proceeding aircraft in sight or some reference like TCAS or weather RADAR skin paint, you can judge by its position to where it's wake should be with the winds you are seeing. Another good wag to put wake in perspective is your mach number. Mach .4 is close to 4 miles a minute. If you are 4 miles behind and same altitude of the proceeding aircraft, the wake is roughly 500 feet beneath you.

When I flew C-141Bs, we did formation and airdrop all the time. We did 10 second minimal interval takeoffs in formation. 2 would break left after lift off and 3 would go right. If you were number 4 or more, you were in wake turbulence the whole time and flight. You routinely would request fluid trail so you could climb 500ft high or offset. The SKE(station keeping equipment) system allowed same altitude and close proximity flying in the weather. The system ensured you turned at the same geographical point as the proceeding aircraft. You could put in an offset to get out of the wake for a while. But, coming across the drop zone, every trailing aircraft was in wake turbulence and it was interesting to see the wings flapping and ailerons working as the jet in front of you worked to stay precisely on target across the drop zone. You would see the aircraft rolling and dropping a couple hundred feet. It was bad enough being at 300 to 800agl getting beat up by thermals, but wake sucked. Being number 7 was the worst. 1 to 3 was prime real estate

... Mach .4 is close to 4 miles a minute. If you are 4 miles behind and same altitude of the proceeding aircraft, the wake is roughly 500 feet beneath you...

All right, that rule sounds simple enough for my cranium to retain:book:

I just hope that the devs are basing their work on detailed info like this...

TBH, so far after few more instances of crossing paths with DCS version of wake turbulence I find it "sort" of consistent with some of that.

There might be some issues with "attachment" points for the vortices as described by one of the Hornet pilots earlier... it would be nice to make these vortices visible (for testing purposes) and I'm sure the devs use some sort of visualization method... eh, perhaps not, it's a sim/game.

I find it absolutely manageable gassing up from S3 (carrier ops freak here:D). I also experienced flying though the wake of a Hornet and some other jets (in single player) at some distance and it was a mild wobble and it was "cool". So, even at this stage of WIP... I'm keeping this feature ON.

The effect is greatly exaggerated at least in some situations in its current form. I am sure it is still being worked on. Somebody else can explain the science but a hornet should not be experiencing extreme turbulence/ 90 deg roll while approaching the drogue on any big wing tanker. Assuming fair weather of course. Behind small aircraft the effect seems very realistic however and is a great touch! Great work and keep the updates coming!

uhh? vortices can be extremely powerful and absolutely capable of flipping you over

Somebody else can explain the science but a hornet should not be experiencing extreme turbulence/ 90 deg roll while approaching the drogue on any big wing tanker.

The web is full of video of the roll effect due to wake turbulence.

But they're surely at work.

I bet not too many around here remember the C-141 Star Lizard....er Star Lifter

Wake turbulence extends many miles back and descends usually at about 2000fpm. I have hit turbulence from other aircraft miles up the road.

I believe I have encountered the effect in the DCS Su-33 while refueling, unless it was my imagination. But the effect seemed rather minor.

Just a light yaw or roll. Annoyance really.

... it would be nice to make these vortices visible (for testing purposes) and I'm sure the devs use some sort of visualization method...

I should've tried it before opening my mouth. At slow speed the vortices were perfectly visible on KC135. Haven't tried faster a/s. I finally tried KC135MPRS and it wasn't bad at all... approaching at proper altitude. I think I was probable imagining the downwash and slight buffet at times;)

https://youtu.be/kTNxDmWLkQQ

It seems to be nice tuned.

uhh? vortices can be extremely powerful and absolutely capable of flipping you over

I’m sure they could. Just saying it’s never happened to me while behind a tanker big or small ;). Still cool they are trying to model this stuff.

This option should be enabled by default. Of course after the corrections have been made.

Yeah, will give a more realistic and immersive flight environment to have it as default.

I have learnt a lot from the experiences posted by expert on this thread.

I hope ED get the wake turbulence refined to allow for a close to real situation.

ED is doing a great job.

guys i cand find "wake turbolence" option, is this removed? was so fun and realistic... (btw my options are in russian language). thanks!

guys i cand find "wake turbolence" option, is this removed? was so fun and realistic... (btw my options are in russian language). thanks!

In English version it's still there: Options ->Gameplay -> at the bottom.

Found it, thanks!