Cessna aerodynamics and VOR

[Panther91]

Hi, I'm new to this forum. Just started flying in this simulation. I've been flying in Falcon 4 Allied Force but flying in an airplane like Cessna 172 which doesn't have a FCC or similar things is something new to me. In this airplane the pilot is completely controling the aircraft by it's own. I have two questions right now which Rod didn't explain in FS2004.

1. If I'm in a straight and level flight and I suddenly change my pitch the aircraft will start returning in the other direction so I have to trimm it to stay in that attitude. But in F-16s, if I change the pitch of the airplane he will stay pitched like I set it. I don't have to trimm. Is this because the F-16s computer is controling the trimm so I don't have to or the reason is something else? I don't know how familiar to F-16s but if someone knows please answer me. By the way, I'm not talking about FS2004 F-16 add-on. The F-16 add-on for FS2004 is not realistic. I'm talking about real F-16s and F4AF F-16s which is realistic.

2. There are two VOR instruments in the Cessna and they seem a bit different. Whats the differents and when do I use VOR 1 and when VOR 2?

[Sean_TK]

Welcome to the world of civilian flight sims, and to Simviation.

Question 1:
Modern combat aircraft and light training aircraft are designed to have different types of stability depending on what they are designed to do. In circumstances like the Cessna, it can make the aircraft easier and more forgiving while in flight. The Cessna you are flying in FS has what I believe is called "Positive Static Stability" or simply Positive Stability. This means that the aircraft is designed to precess to the orientation that it was previously at, after certain lateral and longitudinal movements.
The F-16 has Negative Stability, which I believe means that it basically points where you tell it to, and is not designed to be very forgiving. (Helps with manueverability I believe. Neither of these stability concepts directly involve computerized trimming of the aircraft.

I could of course by off base on some of this stuff, so someone please correct me if I am wrong!!

Question 2:

The big differences in the two VOR gauges in a standard 172 are simply that #1 has both lateral and vertical guidance and number 2 simply has lateral guidance when inbound on an ILS beam. We're talking about localizer and glideslope signals here.
For general en-route navigation, the glideslope indication on number 1 is of no use, and so you basically just have two VOR direction indicator gauges. With this setup enroute, you can more easily do things such as triangulation to figure out your position with a few VORS, or you can simply use it as a backup or something.

[beaky]

Hi, I'm new to this forum. Just started flying in this simulation. I've been flying in Falcon 4 Allied Force but flying in an airplane like Cessna 172 which doesn't have a FCC or similar things is something new to me. In this airplane the pilot is completely controling the aircraft by it's own. I have two questions right now which Rod didn't explain in FS2004.

1. If I'm in a straight and level flight and I suddenly change my pitch the aircraft will start returning in the other direction so I have to trimm it to stay in that attitude. But in F-16s, if I change the pitch of the airplane he will stay pitched like I set it. I don't have to trimm. Is this because the F-16s computer is controling the trimm so I don't have to or the reason is something else? I don't know how familiar to F-16s but if someone knows please answer me. By the way, I'm not talking about FS2004 F-16 add-on. The F-16 add-on for FS2004 is not realistic. I'm talking about real F-16s and F4AF F-16s which is realistic.

2. There are two VOR instruments in the Cessna and they seem a bit different. Whats the differents and when do I use VOR 1 and when VOR 2?

I can't tell you much about the F16, but it's very likely self-trimming to some extent.

As for the two VOR receivers, one has an ILS (the one with the horizontal needle) and the other does not.

[chrism7262]

welcome to simV!!  ;D

i know a bit about the F-16 myself, and i own Falcon Allied Force, and  the game is very realistic. the F-16 like stated above, is more or less a turn and burn, sort of aircraft. meaning that slight joystick movements and pitch changes whip the aircraft around in a sharp manner. whereas the cessna doesnt have as responsive flight controls. speed also plays a dramatic effect on this. the design of the cessna is to bank and turn when the aircraft is rotated, but the F-16 stays on a solid course if banked, but turns when you pull up on the joystick. this is mostly any fighter jet design. the cessnas aerodynamics are similar to airliners, the F-16s are typical of military aircraft. its just a matter of how you control the plane. i sometimes have the tendeny to control a cessna like im a fighter pilot  :D

hope this helps!!  ;)

[Splinter562]

The Cessna you are flying in FS has what I believe is called "Positive Static Stability" or simply Positive Stability. This means that the aircraft is designed to precess to the orientation that it was previously at, after certain lateral and longitudinal movements.
The F-16 has Negative Stability, which I believe means that it basically points where you tell it to, and is not designed to be very forgiving. (Helps with manueverability I believe. Neither of these stability concepts directly involve computerized trimming of the aircraft.

You are correct about positive static stability. Though neutral static stability is where the aircraft "stays where you put it". And negative static stability means that it will diverge, requiring constant input to keep the airplane flying straight. The reason unstable aircraft usually have an FLCS is that the pilot would otherwise have to devote all his attention to keeping the aircraft pointed forward or not be able to react quick enough to fly the airplane at all.


To answer Question 1:

The FLCS on the F-16 does not automatically trim the airplane, but instead moves the entire control surface. Unlike a Cessna 172, the F-16 pilot has no direct connection to the control surfaces at all. Instead, the pilot is basically commanding a pitch or roll rate using the stick. The FLCS responds to that command by moving the control surfaces.

The difference can be demonstrated by flying the same simple maneuver in the 172 and the F-16.
First the 172:
1) Accelerate to a good cruise speed and trim for level flight.
2) Once stable, reduce the power to idle and try to maintain a constant altitude.
3) You'll find that as the aircraft decelerates you will need to pull back on the stick (adding more up elevator) to maintain level flight.
4) Eventually you will stall and no longer be able to maintain altitude with any amount of up elevator.

Now the same maneuver in the F-16 (I don't know how well Falcon 4 simulates the control surfaces. If you don't see this in the sim, trust me that the real aircraft does it)
1) Accelerate to a good cruise speed and pitch the aircraft for level flight.
2) Once stable, reduce the power to idle and don't touch the control stick.
3) As the aircraft decelerates the FLCS will command the tail surface to move elevator up, like the Cessna, to maintain level flight. But it does so with no input from the pilot.
4) As you approach stall the FLCS will reverse and start reducing the up elevator to drop the nose and prevent the stall. (Note: I don't know the particulars of the F-16, but it might have too much idle thrust to stall when clean at low altitudes. You can try dropping the gear or performing the maneuver at a higher altitude if you can't get the airspeed low enough.)

[Panther91]

the design of the cessna is to bank and turn when the aircraft is rotated

Yes, except when you enter a steep turn. Then, there must be a little pressure on the joystick to mantain level flight.

Now the same maneuver in the F-16 (I don't know how well Falcon 4 simulates the control surfaces. If you don't see this in the sim, trust me that the real aircraft does it)
1) Accelerate to a good cruise speed and pitch the aircraft for level flight.
2) Once stable, reduce the power to idle and don't touch the control stick.
3) As the aircraft decelerates the FLCS will command the tail surface to move elevator up, like the Cessna, to maintain level flight. But it does so with no input from the pilot.

Well, the F-16 doesn't act like this in F4AF. If I reduce the power to idle at level flight the aircraft will stay pitched like I set it to but it will start descending due to increase of the AoA. For example if my AoA was 5

[Splinter562]

[quote]
Well, the F-16 doesn't act like this in F4AF. If I reduce the power to idle at level flight the aircraft will stay pitched like I set it to but it will start descending due to increase of the AoA. For example if my AoA was 5

[Panther91]

Is it realistic that all planes in FS2004 act like a Cessna when talking about attitude and trimming? Even the Extra 300S which is a sport aircraft. It's really hard to manuver in this aircraft with high G forces. I think it's really hard for pilots to fly and do acrobatics in this plane.

[pepper_airborne]

True, the default X300 requires a really subtle control, try making a knife edge, you will notice the plane will drop down, and if you try to rudder her back she wont respond. This is deu to the modelling of the flight dynamics in 2004. It does not recognize the rudder as a vertical steering surface when flying on a 90 degree bank angle.

If you practice enough with her your going to be doing all sorts of manoeuvres in no-time, just ease up on the landing, she doesnt handle well if you smack here down.