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Landing AOA...


Donut
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In the manual, it's states that we should trim to an angle of attack of 11 degrees; however, in the landing video tutorial from Wags, he never trims it. Are we to actually use the trim on the stick to get at 11 degrees AOA like what is done in the Hornet?

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No, you don't trim it to AoA.

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No, you don’t need to trim the F-16. In the video Wags made pretty bad approach IMO, with a too high AoA that could result in hard landing and a tail strike.

 

Keep it at 9-10 degrees and go to 11 as you flare. Use your pitch to control your flight path and you engine to control the AoA, kinda like the opposite of what you do in the hornet.

The F-16 is an “always-on” FBW airplane, unlike the Hornet where in landing mode (PA Mode) the fbw acts to simulate a conventional aircraft.

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Landing and takeoff gains are based on attitude (not AOA like Hornet). You should trim for the stabilized approach but changes in power or speed will result in different hands off AOA for the same pitch trim. Generally the airplane is not flown with the trim switch directly but trim is added so that stick forces can be relaxed without a change of input.

 

Two normal approach procedures are 11 degree and 13 degree approach (top and middle of bracket). During the transition to touchdown you want 13 AOA regardless of approach and minimal sink. I recommend using the 11 degree approach first as it allows a later and more simple transition to touchdown.

 

13 AOA approach requires a brief power addition and/or a more gradual transition to avoid exceeding 13 AOA. It's slightly more advanced and I think should be attempted when already comfortable with the 11 AOA approach.

 

The approach is improved by:

1. Flying a 2.5 degree glide path.

2. Put the "--- ---" symbols in line with the very beginning of the runway surface and not the desired touchdown point. The transition to touchdown will take care of shifting impact 500' down the runway.

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Hey guys,

 

I am quite confused now so for example I am straight approaching the runway:

 

In the hornet I would trim to AOA and move the flightpath vector via throttle input.

 

In the viper I would put the flightpath vector to the treshold with stick inputs and then reduce the throttle. When approaching the AOA 11 marker I would increase the throttle a bit to keep it there. Simultaneously adjusting the flightpath marker with the joystic input

 

Is that the correct way to do it?

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Hey guys,

 

I am quite confused now so for example I am straight approaching the runway:

 

In the hornet I would trim to AOA and move the flightpath vector via throttle input.

 

In the viper I would put the flightpath vector to the treshold with stick inputs and then reduce the throttle. When approaching the AOA 11 marker I would increase the throttle a bit to keep it there. Simultaneously adjusting the flightpath marker with the joystic input

 

Is that the correct way to do it?

 

Yup, totally opposite to the F-18. :)

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  • 1 year later...

Is the AOA on the hud offset in the F 16? 

 

After one off the last updates, the tail keep hitting the runway when the huds AOA shows an angel of 11 or 12..

AoA Display-F-16C-D-Flight-Manual.gif

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On 10/5/2019 at 3:43 PM, Donut said:

In the manual, it's states that we should trim to an angle of attack of 11 degrees; however, in the landing video tutorial from Wags, he never trims it. Are we to actually use the trim on the stick to get at 11 degrees AOA like what is done in the Hornet?

I haven't bothered reading this discussion but you're supposed to fly your glideslope at 3 degrees with 11 degrees AOA, you will of course trim your aircraft for that AOA. There isn't any rule for this, but it's just so that you don't need to be holding pressure. 100% personal preference. The flaring is the difficult part of the F-16 landing.

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In -1 section 6 Flight Characteristics, Landing Configuration, there're two described techniques that you can use to land a Viper.

 

One is the 11 deg technique: stick for attitude and throttle for AOA. The reasoning behind is that the FLCS Take-off & Landing Gains is a pitch-rate command system until 10 deg AOA, which means your stick is commanding pitch-rate, instead of G or AOA. A zero stick input will translate to a zero pitch-rate, regardless whether your aircraft is inverted, decelerating or accelerating. This technique allows better pitch control.

 

Another technique is to trim for 13 deg AOA: stick for AOA and throttle for glidepath. When flying above 10 deg AOA, the FLCS starts to add nose-down command to your stick input, a negative pitch-rate command proportional to (AOA - 10). It's called a blended pitch-rate and AOA command system. 

 

When you manually trimmed to 13 deg AOA, you're essentially commanding a positive pitch-rate, while at the same time the FLCS is commanding negative pitch-rate proportional to (AOA - 10). What's happening is that the aircraft will now tend to hold the trimmed AOA. Adjusting the throttle will now pitch the nose up and down. This type of approach primarily allows better control of touchdown point and more efficient energy dissipation, but less stable in gusty wind conditions.

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I just do it by hand/feel. I've never scraped a tail or trimmed for an approach. I put the FPM in the bracket and adjust throttle as needed to keep it there between 150-160 knots. On approach it put the FPM at the beginning of the runway, and is get close I move it to the end. Then right before touchdown go to idle throttle, and let her glide down. Aero brake till about 100-110 knots, and that's all there's to it.

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Ya ever since i heard i think it was fighter pilot podcast with the Viper pilot, saying every landing is different and f16 is hardest thing to land i just go off feel myself as well  and do quite well with it.  Sure check some numbers but more of a feel thing for me anyways.

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17 hours ago, Enduro14 said:

Ya ever since i heard i think it was fighter pilot podcast with the Viper pilot, saying every landing is different and f16 is hardest thing to land i just go off feel myself as well  and do quite well with it.  Sure check some numbers but more of a feel thing for me anyways.

I found it quite easy to land actually, also Viper's landing style is also quite elegant comparing to other jets like the Hornet. I love doing the gentle touchdown and aerobrake on the Viper. 

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  • 3 weeks later...
On 9/13/2021 at 5:37 AM, LJQCN101 said:

In -1 section 6 Flight Characteristics, Landing Configuration, there're two described techniques that you can use to land a Viper.

 

One is the 11 deg technique: stick for attitude and throttle for AOA. The reasoning behind is that the FLCS Take-off & Landing Gains is a pitch-rate command system until 10 deg AOA, which means your stick is commanding pitch-rate, instead of G or AOA. A zero stick input will translate to a zero pitch-rate, regardless whether your aircraft is inverted, decelerating or accelerating. This technique allows better pitch control.

 

Another technique is to trim for 13 deg AOA: stick for AOA and throttle for glidepath. When flying above 10 deg AOA, the FLCS starts to add nose-down command to your stick input, a negative pitch-rate command proportional to (AOA - 10). It's called a blended pitch-rate and AOA command system. 

 

When you manually trimmed to 13 deg AOA, you're essentially commanding a positive pitch-rate, while at the same time the FLCS is commanding negative pitch-rate proportional to (AOA - 10). What's happening is that the aircraft will now tend to hold the trimmed AOA. Adjusting the throttle will now pitch the nose up and down. This type of approach primarily allows better control of touchdown point and more efficient energy dissipation, but less stable in gusty wind conditions.

Maybe I am struggling to understand what this means in terms of the aircraft's characteristics....

But, shouldn't the nose stay parked where we put it with L/G gains and AoA < 10 ?

 

I am further confused by the reports that with weight on wheels this 0-pitchrate behavior still applies,
AKA when I am on takeoff roll and i park my nose 9 degrees high it should stay there, correct?

same with landing rolls?

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  • 2 weeks later...
On 9/14/2021 at 12:46 AM, Dannyvandelft said:

I just do it by hand/feel. I've never scraped a tail or trimmed for an approach. I put the FPM in the bracket and adjust throttle as needed to keep it there between 150-160 knots. On approach it put the FPM at the beginning of the runway, and is get close I move it to the end. Then right before touchdown go to idle throttle, and let her glide down. Aero brake till about 100-110 knots, and that's all there's to it.

Sent from my SM-G960U using Tapatalk
 


Quite the same for me. Trimming and power to get AoA just messes it up for me, esp with the Hornet. The basics I find that that help me in the Viper are (a) to first get it right at the approach, by coming in well below 1000ft and with a slow speed (160-170 knots for me) before the threshold (b) slightly oscillate the throttle near idle but not idle (unless fast) before touchdown, I find oscillating it helps me avoid stalling (c) watch aero brake at close to 15deg pitch for max effect without tail strike (d) pull back a little on stick as front wheel drops to avoid bounce. I only get the AoA centered (13deg) just before touchdown. It feels more natural at 11deg AoA or less during approach. I don't always have the patience for procedures. Sometime I just drop out of the sky, jink to lose speed and declare emergency to land using these basics.          


Edited by GrEaSeLiTeNiN
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And if the approach is steep or really steep for some reason, start the flare at 150 - 100 feet AGL.   If you also have high speed, the flare slower so as not to porpoise.
In general, ideal landings are 1 kt above stall speed, so no chance of bounce and shortest rollout.

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18 hours ago, ACME_WIdgets said:

And if the approach is steep or really steep for some reason, start the flare at 150 - 100 feet AGL.   If you also have high speed, the flare slower so as not to porpoise.
In general, ideal landings are 1 kt above stall speed, so no chance of bounce and shortest rollout.

What is the stall speed of an F-16?  🤔

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What is the stall speed of an F-16? 
That depends on weight. She's so small, loadout and fuel plays a huge part. Landing almost clean with 1000 lbs of fuel she touches down like a feather, but with 4000 lbs she'll clunk on the tarmac if you're not super careful. Not to mention if you're bringing back most of your stores.

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16 hours ago, Dannyvandelft said:

That depends on weight. She's so small, loadout and fuel plays a huge part. Landing almost clean with 1000 lbs of fuel she touches down like a feather, but with 4000 lbs she'll clunk on the tarmac if you're not super careful. Not to mention if you're bringing back most of your stores.

Sent from my SM-G960U using Tapatalk
 

 

Are you sure?

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Are you sure?
Of course not, I can only comment on how it feels in the game, and in the game it feels like it matters. I have a harder time keeping the aerobrake going with a heavier fuel load and/or stores than when she's light. So I would assume landing speeds change depending on how heavy she is.

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Just now, Dannyvandelft said:

Of course not, I can only comment on how it feels in the game, and in the game it feels like it matters. I have a harder time keeping the aerobrake going with a heavier fuel load and/or stores than when she's light. So I would assume landing speeds change depending on how heavy she is.

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You are correct that the speeds correlating with the appropriate landing AOA change based on fuel and stores weight.

 

My question was more of this notion of "stall speed" with regard to the F-16, and how/why anyone would want to be "1 knot above it" for landing.  

 

It's an academic discussion more than anything on how the FLCS works, methods for flying the pattern in a fighter, etc.  The F-16 is not a Cessna.

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You are correct that the speeds correlating with the appropriate landing AOA change based on fuel and stores weight.
 
My question was more of this notion of "stall speed" with regard to the F-16, and how/why anyone would want to be "1 knot above it" for landing.  
 
It's an academic discussion more than anything on how the FLCS works, methods for flying the pattern in a fighter, etc.  The F-16 is not a Cessna.
Yeah I didn't make that "1 knot above stall" comment lol. I just assumed that if landing speeds change on weight, so do stall speeds.

P.S. fan of the channel.

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