Aileron and Elevator Control (or lack thereof?)

[mirage335]

Tried to duplicate a true barrel roll in Falcon 4 BMS, which quickly became confusing. As I understand it, this (and presumably other displacement roll maneuvers) requires independent elevator and aileron control. However, the manual doesn’t seem to say anything on the subject. Additionally, external views only show aileron control, never elevator surfaces, even at supersonic speed.

Can anyone clarify whether it is possible to perform such maneuvers accurately?

EDIT: Found the elevator control keystrokes, although this is a rather slow method.

EDIT2: Still not able to achieve a true barrel roll.

EDIT3: Test for downard thrust with elevators guiding plane up and aileron guiding down was negative. Do I take it this behavior is not simulated in Falcon 4 BMS?

[mvsgas]

Sorry, I don’t follow. Where you able to do a barrel roll? F-16 and all flyby wire aircraft, AFAIK, do not have dependent controls traditionally speaking. You tell the flight computer what you want to do by moving stick and rudder pedals and the computer moves what ever surface it needs to performed the maneuver. Additionally, F-16 do not have aileron nor elevators. It has flaperons and horizontal stabilators (commonly refer to as “stabs”)

[mvsgas]

A true barrel roll is just a roll with pitch. Nothing to do with independent use of flaperon and stabs.

[mirage335]

Notice the true barrel roll maneuver after refueling. Have not been able to duplicate anything like that in Falcon 4 BMS. I do notice that the left stick does have an elevator control knob though.

[mvsgas]

the left stick? you mean the throttle?

[Mav-jp]

Btw the higher speed you fly the lower the surface displacement will be

Do manouvers at low speed you will see your surfaces moving a lot

Finally you dont control any surfaces with your input. You tell the flcs what you want to do and the flcs moves the surfaces for you

The best example is : do barrel rolls at very low speed. Your stick will be full pitch up andthe elevators will be full pitch down… this is due to inertial coupling of the airframe , the flcs commands full pitch down in order to avoid pitch departure while you command full pitch up. Actually the flcs controls the pitch instability of the airframe to make the ac reacts like the pilot wants

Pretty amazing isnt it.

To conclude : it seems you are mixing rudder roll and barrel roll .

yes rudder roll are also possible but difficult to perform because the flcs is cutting the rudder input above a certain AOA because the f16 is subject to roll departure therefore flcs prevents pilot to do bad manoeuvers

barrel rolls are of course easy just pitch and roll

And at the end nzver trust external views because as explained above the “eye” can not understand the instability of the f16

[Dee-Jay]

@mirage335:

Notice the true barrel roll maneuver after refueling. Have not been able to duplicate anything like that in Falcon 4 BMS. I do notice that the left stick does have an elevator control knob though.

This is not a TRUE barrel roll. … a TRUE barrel roll is usualy larger in amplitude (pitch).

EDIT2: Still not able to achieve a true barrel roll.

!!!???!!?!

Barrel roll in BMS with the F-16 shoulnd’t be a problem.

Are you using a joystick? … which model?

EDIT: Like JP said, … especialy if you are trying to do the same than on your AAR video with the AAR door open (AAR gain), try at higher speed with using only pitch and roll inputs: http://en.wikipedia.org/wiki/Barrel_roll

[Mav-jp]

??? There is absolutly no problem to perform the manoeuver seen in this refuel video…even in LG gain and whatever the speed …this is a very basic manoeuver

… you may have a joystick problem ?? Or you just dont know how to do it

[mirage335]

Ok, will retry the maneuver. Dee-Jay, thanks for the video, that is precisely what I am trying to do.

[mirage335]

The elevators and ailerons are both responding to stick inputs now, presumably under FLCS guidance. Last night, the elevators did not appear to be operating.

Currently, the procedure I am using is to pull up slowly to ~30deg, roll slowly right, pull pitch control harder, and continue rolling. However, the aircraft’s yaw does not remain constant. Please see attached ACMI data.

[Mav-jp]

I think you just lack practice . Your inputs shall be extremely smooth to perform a nice barrel roll like in DJ video
If your inputs are too piky you will get adverse movements of the airframe.

[Mav-jp]

@mirage335:

The elevators and ailerons are both responding to stick inputs now, presumably under FLCS guidance. Last night, the elevators did not appear to be operating.

Currently, the procedure I am using is to pull up slowly to ~30deg, roll slowly right, pull pitch control harder, and continue rolling. However, the aircraft’s yaw does not remain constant. Please see attached ACMI data.

FYI yaw can not remain constant , this is normal due to dynamic of the airframe, ARI gets time to catch the adverse yaw

If your induced yawing is too important this is because you have too pitchy inputs which makes the FLCS job harder.

Try to be smooooooth

Of course never touch rudder during the manoeuver as you would prevent the ARI to act correctly

Btw ACMI is shit to show those kind of stuff

[mirage335]

Thanks for the advice. Have had more luck not trying to minimize yaw variation so tightly, still practicing.

[TobiasA]

Getting up with an AI (or human) lead and practicing rolls like dee-jay did in his video is a good practice for that since you have a visual reference for your roll which you don’t have in the plain sky.
At the start of your roll, the other plane is off your nose, same height.
In the middle of your roll, the other plane is on the top of your canopy, but roughly the same angle off.
At the end of your roll, the other plane is on the same angle off, but to the other side.
So, the “fixed point” describes a half circle on your canopy with always the same angle off (for example 30° left, 30° “up” and 30° down). At the end, you need to pull a little harder to prevent dropping too low.
Note dee-jay’s video on 2:37. First he pitches up, then he rolls over to the right, keeping the top of the canopy towards the AI leader until he is maybe 2/3rd around the plane. Roll rate is not always exactly constant in such a roll. On the last part of the roll, you need to roll around a little quicker to prevent the nose from dropping too low.
A barrel roll to switch sides in a close formation is often “flattened out” a little on the top to build up more lateral spacing (the roll is a little wider then it is high), especially when you’re not in fingertip, but need to build up a larger lateral offset. This is called a “canopy roll”.
See here:
http://en.wikipedia.org/wiki/Barrel_roll
and look for “canopy roll”.
The more offset you want, the more “flattened” is the roll.

This one here

will be a more “round” roll with less lateral offset at the end of the roll.

You might be trying to fly a clean barrel roll, but wanting to have a canopy/ displacement roll (which is a barrel roll too, but not flown with constant roll rate). In a canopy roll, you unload the plane for a short moment when inverted to build up a lateral displacement. In a pure barrel roll like in that video, you continue your roll.

Like dee-jay and mav-jp mentioned, you need rather smooth inputs. I did need a lot of practice too… When flying a canopy or displacement roll, don’t focus so much on the roll rate, rather concentrate on keeping the other aircraft’s position on the right spot on the canopy. That helped me a lot. But everyone has its own way to get it working. In doubt, trust dee-jay, he’s a real pilot if i remember correctly

[Stubbies2003]

@mirage335:

The elevators and ailerons are both responding to stick inputs now

I’m going to follow up from mvsgas and pick this nit too. This aircraft does not have anything called an elevator or an aileron. See his post right before your OP.

@mirage335:

presumably under FLCS guidance.

Heh, what other guidance would it be coming from? As others have pointed out the system looks at your inputs then looks at it’s current situation and it deflects the surfaces accordingly to try and do what the pilot wants while also keeping the pilot out of trouble. There are no mechanical links from the cockpit to the flight control surfaces so the system is always under FLCS guidance.

@mirage335:

Last night, the elevators did not appear to be operating.

The system will do it’s best to keep you out of trouble if you try to do something that will induce a spin, etc. Perhaps what you saw as “not operating” was “operating just fine to keep you out of trouble”.

[mirage335]

Barrel rolls definitely take some practice, but I think I have the hang of it now, rolling around AI aircraft. However, close formation flying is extremely challenging still, and I am wondering if the lead AI is actively avoiding a collision.

[Cik]

they do. they are smart enough not to hit you AFAIK, esp. on takeoff and landing where they will give you a very wide berth.

[mirage335]

So, how might I convince the AI to fly straight for formation flying practice?