Elevator Sensitivity

I find that with most all of my aircraft in my hangar, jet and piston powered, when I reach VR and pull back on my Yoke, some of my aircraft react instantly launching into the air and others react very slowly and smoothly, with the same amount of movement on the Yoke. I would like to know what section and what parameters in the aircraft or air file folders control this differing sensitivity, or is it a combination of factors?

 

Thanks

I'd start by playing with the [flight_tuning] section in the aircraft.cfg, but I'd check a LOT more than just how it works at rotation, being sure that the elevator still is sufficiently effective to keep the nose up in the flare and for all other flight regimes, as well. I'd also (very, very carefully) check out the [weight_and_balance] section and the [contact_points] section. And by all means, save a copy of the original file before starting to mess with things.

 

Do one thing at a time, then test it thoroughly before proceeding, keeping in mind that sometimes one thing affects more than it's labeled for, or at least interacts with other things in ways you may not expect. Flight tuning (beyond minor adjustments in the [flight_tuning] section) is something usually needing a lot of experimentation and trial and error, usually quite time consuming.

 

The other place you might find something to change (be very careful) is the 1101 section of the .air file for the aircraft, using AirEd.

 

It also occurs to me that your phrase "pull back on my Yoke" may indicate something more than just adding back pressure and waiting for the aircraft to lift off -- if so, being a touch ham-fisted can be a problem in its own right, since smooth operation of controls makes a difference.

Edited January 10, 2021 by lnuss

It will also depend on the aircraft, be it default or 3rd party addon. Most, if not all, TDS aircraft will require a good amount of elevator trim to be able to takeoff. I have heard stories about TDS aircraft going down the runway at 250 knots and still won't get airborne!

Thanks Inuss and Mr. Zippy for your input. As an example referencing my post, I find that the default A321 lifts off at VR with a tail strike in mind. It doesn't strike but comes awfully close. As opposed to a Project Airbus A320 (yes it is a bit shorter in length and weighs a bit less than the A321) which lifts off very smoothly with a nice flare. Obviously some huge differences in the flight dynamics between the aircrafts. I am going to start by swapping the flight tuning sections from the PA to the default understanding that weight and balance are not the same between the aircrafts. It should be an interesting experiment.

G'day miatamariner, The best way to make control sensitivity changes is to install Pete Dowson's FSUIPC4 software for FSX. This will allow customizing controls for every different aircraft in your hanger and it remembers your settings for each aircraft! It provides many other additional capabilities re control assignments for specific aircraft, far better than default MSFSX - it's been a game changer for me. Check it out! Best wishes, Max

I am going to start by swapping the flight tuning sections from the PA to the default

As you may have discovered by now, that could cause as many (or more) problems as you had to start with, so extreme care is needed, and save a copy of the original.

 

I find that the default A321 lifts off at VR with a tail strike in mind

 

Just a suggestion: VR as an abbreviation has several meanings, so when you mean rotation speed, using Vr instead (V_r even better) would make it instantly clear which meaning you were abbreviating. Thanks...

As you may have discovered by now, that could cause as many (or more) problems as you had to start with, so extreme care is needed, and save a copy of the original.

 

I made a change to "pitch_stability" from 1.0 to 1.5 and it seemed to have a positive effect at liftoff, not making the radical notchy nose up movement that I experienced at the 1.0 setting. Now, I am a complete novice as to flight dynamics and understand that I could be all wet with my observation, but to keep the scenario as neutral as possible, I made a mark on the shaft of my Yoke as a reference point not to be exceeded at liftoff. This is a complete learning experience for me so set me straight on whether the change from 1.0 to 1.5 would have either a positive, negative or no effect on what I had initially observed.

 

 

 

Just a suggestion: VR as an abbreviation has several meanings, so when you mean rotation speed, using Vr instead (V_r even better) would make it instantly clear which meaning you were abbreviating. Thanks...

 

OK, my reference to Vr would by V as you described. It is the speed that Rob Barengredt's VSpeed4 gauge is listed as Vr on the gauge.

 

Thanks

I don't think I had ever even come close to a tail strike with the default A-321. Sounds like you are yanking on that yoke a bit too hard!

 

(yoke yanker)?? Smooth and gentle yanking will get you off much easier! :p :eek: Where's my mind roaming to these days??

A suggestion:

 

Smooth and gentle yanking will get you off much easier! Where's my mind roaming to these days??

I would prefer:

 

Smooth and gentle pressure will get you off much easier! Where's my mind roaming to these days??

 

as being more accurate in expressing what's needed.

A suggestion:

 

 

I would prefer:

 

 

 

as being more accurate in expressing what's needed.

 

Sounds good to me! ;) Maybe a rusty yoke?? A little lubricant?

I don't think I had ever even come close to a tail strike with the default A-321. Sounds like you are yanking on that yoke a bit too hard!

 

(yoke yanker)?? Smooth and gentle yanking will get you off much easier! :p :eek: Where's my mind roaming to these days??

 

I should probably be true to form and use my Saitek Avi8tor joystick seeing that it is an Airbus product.

Hi Chris,

 

Euhhh ... long time ago we had contact .....LoL

 

I think the problem MIGHT be (and has nothing to do with elevator sensitivity), is that you are trying to rotate too early in the takeoff run.

I.e. that the Vspeeds (V1, Vr) you rely on, don't match the actual aircraft flightmodels.

 

Best, Rob

I was thinking something similar. If the rotation reaction to pulling the yoke is too strong you may simply be rotating at too high speed.

 

In your other thread you mentioned a Vspeeds gauge. (you posted an image of a gauge and were looking for the creator of it.)

Those gauges are almost always made for one specific plane. (Very specific. So for example only the default fsx 737-800 and not other 737's)

 

So try rotating at some lower speed.

 

Also dont forget setting full flaps for takoff. Taking off without full flaps would be at higher speed and would be more erratic at rotation. You dont want either of those things.

 

By taking off with full flaps (and enough trim) every time you will quickly find the sweet spot for rotation in that plane.

 

Flying all sort of different aircraft every flight will prvent building consistency. All aircraft behave differently. Even different 737 addons. Stick to one aircraft untill you know it inside out.

(Same as with real aircraft really. Very few pilots are qualified to fly more then on airliner type. Almost all fly one type only. And transitioning to another type requires a lot of trsining and numerous supervised qualification flights under supervision of a training pilot.)

Edited January 12, 2021 by il88pp

I was thinking something similar. If the rotation reaction to pulling the yoke is too strong you may simply be rotating at too high speed.

 

In your other thread you mentioned a Vspeeds gauge. (you posted an image of a gauge and were looking for the creator of it.)

Those gauges are almost always made for one specific plane. (Very specific. So for example only the default fsx 737-800 and not other 737's)

 

So try rotating at some lower speed.

 

Also dont forget setting full flaps for takoff. Taking off without full flaps would be at higher speed and would be more erratic at rotation. You dont want either of those things.

 

By taking off with full flaps (and enough trim) every time you will quickly find the sweet spot for rotation in that plane.

 

Flying all sort of different aircraft every flight will prvent building consistency. All aircraft behave differently. Even different 737 addons. Stick to one aircraft untill you know it inside out.

(Same as with real aircraft really. Very few pilots are qualified to fly more then on airliner type. Almost all fly one type only. And transitioning to another type requires a lot of trsining and numerous supervised qualification flights under supervision of a training pilot.)

 

Your comment about full flaps for take off is very interesting. I was never under this impression that full flaps are/were required for a takeoff. I am not a pilot and only base my comment on what I have garnered over the years from YT videos of real flight operations and what knowledge I have gained on this site. I generally select 10-15 degrees flap for a takeoff based on the weights and balance section of each aircrafts cfg file. I've been under the impression that higher take off weights would require more flap extension to get airborne before you run out of runway. Am I correct in this assumption? And thanks for your input.

Regarding flaps. The more flaps the more wing surface, and more wing sueface means more lift.

Meaning with more flap you will already have enough lift to take off at a lower speed.

 

Keeping speed low has many advantages. Easier to abort on case off emergency for one.

 

Some think full flaps mean you need more runway to get to takeoff speed but that is wrong. Flaps add a lot of drag making it harder to accellerate.

With less flaps you accellerate faster, but, as you need to accellerate to higer speed for Vr the distance required for accelerating to Vr is still the same as when using full flaps.

 

Imagine the result. In both flap situations the takeoff happens at nearly the same point down the runway. With the same amount remaining. With full flaps however you will be going at much lower speed. Easyer to stop if needed, easier to control, and much less stress in the cocpit as things aren't happening so fast.

(btw, in fsx the drag effect of flaps on the ground is not modeled well and is lower then it should be, so there's no reason not to extend them and grab some extra lift.)

 

Reading online about the real world 737. (boeing's own website, takeoff guidance, flaps) I read that flap setting for takeoff should always be either 35 or 40. Never less then 35.

 

I don't warch fsx facebk videos but flaps 10 on a 737 seems madness. Not tried it, at least not recently, but looking at max flap speeds and such I'd say you'd need to be going around 200kt+ (360 kmh) before you have enough lift to get to rotating. With full flaps that would have been a much safer 135kt (243 kmh).

 

Regarding weight.

My observation with more weight on board is: accelleration needs to be done gradually and carefully, is slower and takes longer/more distance. (duh, large weight is harder to shift).

More trim is also needed.

I would also takeoff with full flaps for sure to have as much lift as possible to lift that weight. (but i do that always anyway, even without full fuel an aircraft is heavy).

And as acelleration takes longer/more distance I would make sure to get assigned the longest runway. (by first taxiing to a spot near that runway's start position and only then contacting atc ).

 

Imagine running a race with a heavy bakpack on your back. It takes longer to accellerate. And takes more distance. By the time you are finally at speed all the other runners (without backpacks) will be far ahead of you.

 

One more thing regardin flaps.

Setting more/full flaps means the "point of lift" moves backwards. (as flaps extend far behind the wing).

That means the point of lift moves closer yo the "centre of mass".

Same effect as when you for example want to lift a heavy beam off the ground. To do that you want to grab it in the middle, where the centre of mass is. If you pick it up closer to one end the other end will keep resting on the ground. (...tailstrike...:D)

Edited January 12, 2021 by il88pp

Your comment about full flaps for take off is very interesting. I was never under this impression that full flaps are/were required for a takeoff.

Real world aircraft don't usually use full flaps for takeoff, partly because they add so much drag. Typically the 10º-20º range, or so, is what's mostly used, though under certain conditions a few aircraft (Super Cub comes to mind) might use full flaps, but even that's not usual.

 

Flight characteristics in the sim often don't match the real world, and lots of folks have picked out work-arounds for problems they encounter, even though those techniques might not be good in real aircraft.

 

higher take off weights would require more flap extension to get airborne before you run out of runway. Am I correct in this assumption?

Not to my knowledge. That mostly adds drag, which doesn't help. Heavier weights require longer runways. In the sim all bets are off because, as I mentioned above, sim aircraft so often have odd characteristics.

To add to what Larry wrote, not all aircraft require flaps for takeoffs. Cessna 152s, Cessna 172s, and Piper PA-28s do not require flaps in regular takeoffs. Some GA aircraft do not have any flaps!

 

In addition, different airliners have different flap settings. For an Airbus A321, there are 4 flap notches and you use the 2nd notch. For an Embraer E170, there are 6 and you use the 4th. The E170 more approaches "full flaps" than the A321 even though the A321 is bigger. So look at the simulated or, failing that, real aircraft's documentation to see which flap setting is best for the aircraft you are simulating.

 

For takeoff speed for normal takeoff, follow the checklist and correct flap setting for that aircraft. It will get you to Vr the soonest. When you rotate make sure the nose is at an appropriate pitch and trim as needed to maintain it during the climb. The correct pitch will gain altitude most effectively and also prevent the aircraft from speeding up too much too soon. Airliners usually have power reduced once the gears and flaps are back up as not to exceed 250 KIAS below 10,000 feet - at least in the States.

Thanks il88pp, Inuss and TextRich for Flaps 101. Great insight and info here. With the default 737-800, I have always used 10-15 degree flaps and with default weight and balance brings me to around 145-150 knots Vr. Good point about shorter runways, lower speeds and liftoff point.

For the 737-800, I have never used more than 5 degrees of flaps on a "normal" length runway. (major airports). Now testing at my test airport (LO8) 5,000 foot runway and with a full fuel load, I would increase to 10 degrees flaps and never used the full amount of runway for takeoff. Heck, even flying the 747 out of LO8, maybe 20 degrees flaps and would be airborne before the end of the runway! ;)

For the 737-800, I have never used more than 5 degrees of flaps on a "normal" length runway. (major airports). Now testing at my test airport (LO8) 5,000 foot runway and with a full fuel load, I would increase to 10 degrees flaps and never used the full amount of runway for takeoff. Heck, even flying the 747 out of LO8, maybe 20 degrees flaps and would be airborne before the end of the runway! ;)

 

Yeah, I'm still trying to wrap my head around "full flaps". Guess it is dependent on runway length, weigh and balance of the aircraft. Going to see if I can get airborne at Lukla with the 737-800 using full flaps. If you never hear from me again, you probably will be able to find me at the bottom of the valley! :)

Edited January 12, 2021 by miatamariner