Crosswind Landings / "Impossible Landing" TE / Crosswind landing advice
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This seems to be unique to the f16. Are there any other aircraft that right themselves while landing in crosswind? In BMS just now, landing in a 15 knot crosswind from left to right, the aircraft yawed itself to the right, while the rudder went hard left to try to arrest the yaw.
I’m just wondering what in the design makes it different.
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This seems to be unique to the f16. Are there any other aircraft that right themselves while landing in crosswind? In BMS just now, landing in a 15 knot crosswind from left to right, the aircraft yawed itself to the right, while the rudder went hard left to try to arrest the yaw.
I’m just wondering what in the design makes it different.
Juts my opinion, the landing gear. The way they landing gear compress, etc. Part of it. Aerodynamics and other things come into play.
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Wish I knew about this when looking for a project in my stability and control class. heh.
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This seems to be unique to the f16. Are there any other aircraft that right themselves while landing in crosswind? In BMS just now, landing in a 15 knot crosswind from left to right, the aircraft yawed itself to the right, while the rudder went hard left to try to arrest the yaw.
I’m just wondering what in the design makes it different.
not really unique… you get a similar reaction from an evektor sportstar LSA. of course, you will also likely pull tyres off too, and it wont be as violent…
the main gear are aft of the CoG. they also have a fair amount of friction - loads more if they are not aligned with the direction of travel.
the momentum is forwards, and that will want to drag the gear as the point of contact behind the CoG relative to the direction of movement…
the rudder part is due to the FLCS, but the rapid yaw right is more than I would expect to see if both gear touch down simultaneously.
I dunno. I started out thinking it wasnt a massive difference, but now that I reflect, it is a fairly violent maneuver (in BMS).
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This seems to be unique to the f16.
Absolutely not. Same on Mirage2000, Rafael, certainty on F22, Typhoon etc … And (IIRC) on
(not 100% sure)EDIT:
For A380:
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Absolutely not. Same on Mirage2000, Rafael, certainty on F22, Typhoon etc … And (IIRC) on
(not 100% sure)EDIT:
For A380:
And the space shuttle it’s pretty much standard landing for every FlyByWire aircraft…
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For Duck Hawk:
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Can someone tell me what the chime is @ 20 sec?
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This seems to be unique to the f16. Are there any other aircraft that right themselves while landing in crosswind? In BMS just now, landing in a 15 knot crosswind from left to right, the aircraft yawed itself to the right, while the rudder went hard left to try to arrest the yaw.
I’m just wondering what in the design makes it different.
I already answered to that argument.
Flcs has nothing to do with this. This is just basic physics, the friction on gear and the fact wheel can only rotate around 1axis forces the AC to align on its velocity vector. The torque generated is a function of tire friction which is dependant on tire rubber / runway/ weight on wheel, tire pressure.
All AC in the world have this, of course a A380 is less sensitive because yaw inertia is too much important.
I can’t say if the BMS behavior is too much or not as so many parameters enter in the game here. I would need to land a f16 myself to judge
However it has nothing to do with FLCS, the rudder effect is just a consequence of the physical effect not the cause
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yay I was right
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the main gear are aft of the CoG. they also have a fair amount of friction - loads more if they are not aligned with the direction of travel.
That makes sense, but there is more than just tire friction acting on an aircraft during a crosswind landing. The moment that the main gear provides is countered by the weathervane effect of the aircraft. You still need some rudder to keep the plane from turning into the wind.
I dunno. I started out thinking it wasnt a massive difference, but now that I reflect, it is a fairly violent maneuver (in BMS).
It might be exaggerated a bit. Maybe its not, since the plane is pretty small, heavy, and has a fairly high landing speed. Its not like I could say tho, the planes I’ve flown have a hard time cruising at its touchdown speed. The f16 video posted above does show a strong correction at touchdown, which looks similar to what we see in BMS.
Quote Originally Posted by starbird View Post
This seems to be unique to the f16.
Absolutely not. Same on Mirage2000, Rafael, certainty on F22, Typhoon etc … And (IIRC) on A380 (not 100% sure)The difference between what I see in BMS and that 380 landing is that the 380 needs a lot of rudder to decrab, where the BMS f16 needs no rudder at all (not just input, no rudder movement). But I do agree that the effect is correct.
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hmm. with you on the difference between their VSO and our VNE!!!
I havent thought of it as need rudder for this, I think of it as keep it on the centerline. but yeah, they weathercock. hmm. I still dont think my friction Idea is that far off though. in BMS, you have a heavy plane, so it is less affected by weathercocking.
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I expect the same answer but I got different answer from the pilot, he flies 1350 hours F-16A/B and said decrab was needed just before touchdown and the secondary effect of rudder (roll) was still small.
But maybe it’s because he flies the block 15. I don’t know about block 50. Just fyi…
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@Duck:
But maybe it’s because he flies the block 15. I don’t know about block 50. Just fyi…
IMO, no big differences (or even no differences at all) between blk15 and 52 … but ?
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**EDIT
Asked again … here is the right answer.**
@Duck:
But maybe it’s because he flies the block 15. I don’t know about block 50. Just fyi…
Welll … finaly … maybe!?..
I just have an answer from a MLU pilot … unfortunately … I’ve closed the Skype windows before having the time to note exactly what was the sequence of his response … but IIRC …
AAR: No.
Flight: No, not recommanded, forbidden sometimes (see -1)
Landing: no, no, no -
Just to give in some input here, i have read this on F-16.net, it is forbidden but some pilots do it. Here is the story:
"Gums you got it but I am tally, visual, supporting if required.
But wanted to comment on the wing low thing. Had to land in 25 knot cross wind on an early BFM ride in B-course. Had Jose Oberly (SP?) in my pit so I was intimidated, as he was a legend and I admit the BFM had not gone well. Went OK as you mentioned so had confidence from then on. Only problem with crab to touch down is that often crosswind decreases close to the ground and you wind up with too much crab and jet tends to tip into the crab at touchdown because your mains are at an angle to your flight path. Not usually a big deal but a lot of roll control opposite the tip could make the trailing edge of a big slab hit the ground. Never happened to me but did to others.
Kids do not try this at home but after I had several K hours in the jet I used to kick out some of the crab while I was in the flare, rudder in rudder out, so there was not enough time for drift to build up but aligned the fuselage more with the runway and i found that far preferable. But as I said that was after several thousand landings when I could tell the right time. It was not a wing low method and the rudder was neutral when I touched down. Never taught anyone or advocated to anyone to do it…just did it myself.
But the Jose story I wanted to relate because I used it later to teach IPs about additive stick input in a family model. As I said, Jose was a god. He was CC of the 72nd, had done the stuff at Nellis that nobody would talk about, and could walk on water as far as the other IPs, and by example us studs, at Macdill were concerned. This was my first DBFM ride and my first ride with him. Seems I was always clueless and out of sync with what he was thinking and obviously wasn’t doing too well in his mind. When I was thinking break, he was saying “extend”, and vice versa. Finally as the training aid IP was getting close at high angle off I was thinking he was still too far away and too few angles so I chose extend. Jose thought it was time to force an overshoot. He said “hook 'im” twice but JB was already unloading to extend. On the third “Hook 'im” he decided to help me by grabbing the stick in the back and “hooked him”. My extension to that point had recovered enough airspeed that there was a fair amount of G available and, looking back over the seat and unprepared for the onset, my head went down between the ACES II pitot tube and the canopy and stuck there. The “AAAUUUGGGGHHHH” sound I made scared the crap out of him and he eased off the stick (I know what it sounded like because of the tape review). I slowly pried my head free of the tight place and regained my composure. He decided we needed to go home and we did through some really bad weather that I had a hard time staying on the wing. The only good thing in my grade book for that ride was the landing in a 25 knot Xwind. I don’t think I ever flew with Jose again and guess I never redeemed myself with him. But I learned a lot from that and he was always good to me after that. Used that story to teach new IPs that you cannot “help” a student by getting on the stick as he had no idea you were helping and the results could be very counterproductive. Also made it clear never paddle off in the flare because you got neutral slabs for a second (go around is throttle up) and rudder out of a too-close formation situation vice trying to help on the stick. Make sure the stud knew you were doing it.
Workin hard on some motor stories to get TEG and crowd fired up but currently can only remember the first motor I saw going through academics. Looking into the burner can of this engine in the shop we could see thousands of little pieces of burnt white cloth hanging on the spray rings like burnt laundry. Turns out a crew chief, seeing some fluid on the nose strut of a running jet, wanted to wipe it off to make sure there was no persistent leak. Only thing that came to hand was the sleeve of her white bunny suit (which thankfully she was no longer wearing). As the large white garment rapidly disappeared from her hand into the intake I guess she figured out it was not a good idea. Better it than her. I hadn’t even flown the jet yet and it gave me a healthy respect for the F100-PW200 intake. You can’t script them like that and I credit our academic instructor for taking us to the engine shop to see it vice sitting around in a classroom looking at slides. Tried to use that same technique years later as an instructor myself. Engine shop guys were surprised at first by my requests to bring a class out but it became routine thereafter. I learned a lot from those trips. JB"
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the dash one mentions a lot of things, but I dont recall seeing rudder as being one of the prohibited things…
had a read through the HAF one you can find online, and searched for every time that the word rudder appears in it.
apparently I am not supposed to command maximum roll rate rolls consecutively, but other than that its mostly common sense.
I havent really had a problem with crosswind landings in the BMS F-16. I just use the FPM instead of visual cues. problem solved.
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Lets wait comments from a (funny :nosep: ) guy here that accidentally; had a full pedal press 100ft AGL at night while on auto TF…
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the dash one mentions a lot of things, but I dont recall seeing rudder as being one of the prohibited things…
PROHIBITED MANEUVERS
The following maneuvers are prohibited:…
1. Intentional departures and spins with any of
the following:
Symmetric category I loading with suspension
equipment or missiles at station 3, 4, 6, or 7.
Asymmetric category I loading.
Category III loading.
Altitude below 30,000 feet AGL.
CG aft of aft limit for the configuration being
flown.
Lateral fuel (internal and external) imbalance
greater than 200 pounds.
2. Repeated m aximu m rudder reversals.
3. Consecutive 360degree maximum command
rolls.
4. Maximum c ommand r olling m aneuver s above
1.8 mach and either above 3g or below 35,000
feet MSL.
5. Rudder rolls or rudderassisted rolls of more
than 9 0 degree s of bank angle change w it h any
store on station 3, 4, 6, or 7.
6. With LG and/or TEF’s down:
Flight above 15 degrees AOA with stores at
station 3, 4, 6, or 7.
Maximum command rolls of more than 90
degrees of bank angle change.
7. Abrupt roll reversals above 550 knots and
below 20,000 feet MSL with the STORES
CONFIG s witch in CAT I.
8. PX III With CFT’s installed, abrupt roll
reversals above 500 knots with the STORES
CONFIG s witch in CAT I.
9. LESS b6n Rapid rudder release or reversal
above 300 knots/0.6 m ach.
10. LESS b6n PX III F ligh t w ith CFT’s installed and
CAT III configurationspossibly the prohibition is a sqn standard rather than a manufacturer standard?