Kelly Rohrbach

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Hey fellas
Just curious if anyone has much experience with the leading edge flap on this model and if so any notice either way in performance.
Thanks in advance

FalconWings

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subscibed. (if only I could find the subscription button!)

Flynstuff

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Kelly, What do you want to know... I'v tested a couple with good success. I also have an extra set if your looking..

Kelly Rohrbach

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Hey Jeff
Just being a scale guy it looks cool but just wanted to see if it really made any difference or not in the landing pattern so to speak. I realize with the extra weight of servos it may be a wash.

Flynstuff

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Kelly..

The slats work well. Make sure you use metal arms 8711 or equivalent servos and carbon rods. You only need about 1/4" movement to see a difference. They do help a little with the high alpha and landings, And they look cool.....

I have a new set all white gelcoat that i'm not going to use if interested. Make you a great deal on them....

FenderBean

from what I understand the real f-16 only uses the leading edge flaps on take-off.

Doug Cronkhite

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That would be incorrect. They're controlled by the flight computer and used throughout all flight profiles. They droop in High G situation, and actually raise up at high speeds to reduce drag.

Kelly Rohrbach

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That would correct Doug, any inflight video shows them moving often. Thanks for the offer Jeff, but I'm just in the planning stage so right now I would have nothing to attach them too, but thanks for the offer and the information.

Gerald Rutten

That's correct! The flight computers can do all sort of things to them which is clasified but in general they are indeed extended at high alfa, slow speed and jerking the elevator quickly for a high G turn. It looks very cool on a model as well! I use them only on landing and high alfa which makes the model just I bit more stable.
Here some very nice pic's NOT in landing config in contrairy of FenderBean's comment. Actually, they must be retracted on take-off roll otherwise rotation is difficult. Just after lift-off they are extended to full deflection.

Best regards,
Gerald

FalconWings

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This is where the magic happens. These two guys (one on each side) move as AOA changes. Each port moves independently from the other, and each has a slit that lets air in and tends to stay aligned with the forward movement vector. The rotation of each port and the forward speed is fed to the air data computer and a signal is set to the flight control computer, which then moves the LE Flaps as required. During takeoff an landing, the LE Flaps are also controlled by an FCC boolean that "knows" you are in takeoff or landing mode.

Gerald Rutten

interesting info, makes sense.

Here's a very nice clip of the former dutch demo team where you can see the LE's working. Right after rotation (1:28min) they move to full extend. Also interesting to see the elevators pumping after brake release, the flight computers trying to catch up ha ha ha!
Right after touch down they go to full up (+2 degrees) to dump the lift. Would be interesting to accomodate that on a model. Below a short clip of my set-up to make it very easy on controls.

Rgds,
Gerald

http://www.youtube.com/watch?v=Ha2qzwtKZig http://www.youtube.com/watch?v=b6UlRfWg_kM&list=UUez__McmYuGvSUES8bGXfoQ

FalconWings

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I wish there was a video of the F16 stalling at high alpha, then you could see what the FCC is really capable of doing. Don't look anywhere else, this is the best fighter ever. (sorry dad, the P-47 was great too!)

John Redman

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All correct as Falcon Wings states. and the flaps do not come into operation until the nose wheel has left the ground. Their activation for movement is controlled thru the nose weight on wheels switch.
So running down the runway they reside in the 2 degree up position until rotation of the nose wheel. Upon touchdown they remain active until the nose wheel touches down. So the point here is they are not down at all when running down the runway.

AndyAndrews

John,

Get with David Ribbe. I think he has some not so good experience with the slats on the SM F16. It was either him or Dustin. I remember hearing a story about them at JWM.

Andy

Kelly Rohrbach

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Thanks for all the info guys

AndyAndrews

LOL, don't know why I addressed that to John, sorry. I meant Kelly.

Peter Coers

On 3.47 you can see the LEF going up when the mains touch the ground, not the nose wheel!

Conversely they will be scheduled at -2 degrees during take off until weight is removed from either main landing gear WOW switch at which point they drive to +15 until airspeed increases. For the LEF to have a deflection of 20 or 30 degrees, the airplane must be subsonic at a relatively high AoA, say 20 or 22 degrees The speed must be subsonic since the LEF is always at -2 deg when supersonic.

http://www.youtube.com/watch?v=lmlQMiIZtUg&feature=player_embedded

yeahbaby

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BOOOOOOOOOO David .......Boooooooooo

LOL gotta love that little lawn dart....tasty meal for a ham fisted-big chief paper and crayon writing knuckle dragger like someone I used to know. LMAO....Ok Ok Big John perhaps in a knife fight.....long range???? well.....a kills a kill right? cheers

Andy I think it was Jeff Tolomeo you were thinking of with the SM F16 LEF dilemma.

SJN

Try this one

John Redman

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Thanks Peter and SJN. Never knew they came up on wheel spin up at landing. Makes total sense. I remember all of the ops checks we did on those and always had to have the nose scissors disconnected for them to work on the ground. Flight control computers are awesome pieces of equipment.

Spencer K

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As depicted in the diagram, the LE flaps retract to -2 degrees upon wheel spin up to act much like ground lift dumpers (Inboard spoilers) do in our airliners. This prevents bouncing and wind gusts lifting the airplane after initial touchdown!

ozief16

My Feedback: (13)

Guys,
yea, they kick up as soon as you touch down and thank God they do b/c that plane keeps flying all the way down to 90 Kts or so!! No kidding, you're flying it, especially in a x wind until 90 or so despite landing at 150ish. If they stayed locked down it would be worse yet! They don't deflect with G, but with alpha, or AOA. Falconwings mentioned the two AOA probes and that's most of it, but there's a third AOA source as well. Computer throws out the outlier, averages the other two and give you flt control inputs.

On the ground they're always kicked up two degrees. It looks like a misaligned wing

Dave

FalconWings

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Of course lest not forget the work of the award winning, Collier prize standard setter........The FCC: the heart of fly by wire, coupled to the magnificent Air Data Computer.

As close to perfection as there is, and the reason the Viper flies like a Viper.

Hornet pilots need not comment. :-) hahaha

Chris Nicastro

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http://youtu.be/c-UHWJf0Gk0

Check out this F-16 and Mig 29 duel at an air show. Nice tight slow speed display looks to me like either the Viper driver is a better pilot or the Mig can't keep up!