General Question Can't fly with joystick or keyboard

[Mipada]

The first time I used a flight simulator, I pitched up to the angle I wanted, let go of the joystick to do some keyboard operation (like raise the landing gear), and nosedived into the ground.
It seems like you don't have to map the joystick input directly to the ships angle. The same with keyboard input. I have to tap the key I want every 0.5 seconds – not any more, not any less – to hold steady. And, I don’t even think about trying to perform some other keyboard operation with the same hand.
Is it possible to make another control mode? If you move the joystick a little bit, you get a little angling of the elevator, aileron, rudder. If you pull back a lot on the joystick, you get a large angling. When you go back to close to no angle, it snaps to no angle. If you set it back to the center, then you can let go and have the pitch, yaw, roll stay the same.

 

[Hielor]

You should look into using the trim controls, since that will do what you want--allow you to keep the ship at a given angle (more or less) and take your hands off the joystick.

If you want more explanation of how it works, maybe start with this video (random explanation I found):

I don't know offhand what the trim controls in Orbiter are; check the manual.

 

[Face]

It seems like you don't have to map the joystick input directly to the ships angle. The same with keyboard input. I have to tap the key I want every 0.5 seconds – not any more, not any less – to hold steady. And, I don’t even think about trying to perform some other keyboard operation with the same hand.
Is it possible to make another control mode? If you move the joystick a little bit, you get a little angling of the elevator, aileron, rudder. If you pull back a lot on the joystick, you get a large angling. When you go back to close to no angle, it snaps to no angle. If you set it back to the center, then you can let go and have the pitch, yaw, roll stay the same.

If I understand that right, you think that Orbiter maps the joystick/keyboard deflection directly to ship angle? And propose that it should instead map it directly to controlling surface angle?

If so, you must know that it already is that way. It is just that a given controlling surface angle with a given airspeed will produce a given rotation moment around the controlled axis (ship pitch for elevator, ship roll for aileron, ship yaw for rudder). Real aircrafts do it the same way. If you keep your stick deflection constant, you will continue to roll. In principle you would even accelerate your roll constantly, but the air resistance (and changing air flow angle) practically makes it a constant roll velocity.

What Hielor said above is right: you can release the needed pressure on the stick by means of using the trim controls. In principle these produce a momentum to rotate the control surfaces, which themselves produce a momentum to rotate the ship.

 

[zerofay32]

What you describe is how aerodynamic control surfaces are supposed to work and while the aero modeling in Orbiter isn't perfect it does a good job for a simulator that focuses on Space flight.

Orbiter 2010 manual says trim is [Insert] and [Delete] keys and it should be Insert for nose down trim and Delete for Nose Up trim. Your trim setting is displayed on the glass cockpit HUD next to your RCS indicators. Only a few addons have a trim indicator in the VC (maybe the DG).

To use trim, lets say you pitch up to begin a climb. To keep the angle you have to keep back pressure on the joystick. In a real aircraft (or if you have force feedback) if you add Nose Up trim, the pressure on the joystick will reduce as the aircraft is trimmed. With a non-force feedback joystick you will have to reduce your back pressure as you add trim otherwise the added trim will cause the nose to pitch up further than the intended pitch angle. Once the joystick in centered and the aircraft remands at the commanded pitch the aircraft is trimmed and should fly 'hands off'.

Airplane aerodynamic surfaces are designed to be streamlined to the non-movable parts at a specific attitude/airspeed combination (usually normal, un-accelerated flight at a normal weight and loading). Any departure from this balanced condition will require a control surface to be held out of its streamlined position by continuous control input. Use of the trim relieves that requirement by changing the shape of the control surface. Any change in weight or thrust or drag or lift will require an attitude change/trim change. For pitch trim a good rule is the plane will be trimmed for the airspeed that you are flying. Any change in airspeed, desired or otherwise, will require a pitch change and Trim change.

Hope that makes any sense... didn't plan on writing a book. :lol:

EDIT: Or just watch the video Hielor posted. That's a pretty good explanation... :goodposting:

 

[Mipada]

First of all, thanks for your replies.
Hielor, I checked with my brother who is a pilot to confirm what I thought – the trim tabs are really to balance the plane (front to back/left to right) do to the weight differentiation of the load (passengers/cargo) so that the plane flies straight and level without constant adjustments to the flight control surfaces. It does help though to fly the DGIV at a nice pitch. But, also, if you let go of the stick, a real plane will level off over a couple seconds but, the DGIV goes completely out of control. I just want something that doesn’t go into a spin that you can’t get out of.

OK, do this. Start KCS to ISS and look at the back of the DGIV. Press the 2 key and watch the elevator go up about 40 degrees. It’s the same for all the control surfaces. They overreact to the key press.

What I’d like, is to be able to have the elevator angle over a second from 0 to 40 degrees. After 20 degrees you can stop pressing the key or pulling on the joystick, and the elevator will hold that angle. That should keep your nose up until you reach orbit. (Though, in real flying, you can get your angle and then flatten out the control surfaces.) If you want to level off, press the other key and the elevator will move back to 0 degrees.
Ah, I realized that I would like the control surfaces to work like the trim (whether by joystick or keyboard)!

The other problem I have, is what someone else wrote in another post – you can use the joystick to angle the ailerons to put the DGIV in a 45 degree bank, but the plane doesn’t turn. It just rolls 45 degrees and keeps going in the same direction. I watched one of the tutorials ‘Stunts’ and the pilot was able to fly around, find the airport and land again on the runway. I still need practice to be able to do that, but I don’t think it should be that hard. It is not relaxing fighting every pitch and roll. (I’ll look into getting another, maybe better, joystick.)

Zerofay32, you said that there is a limitation in flight sims... sadly, this is so. But, I think it is easy to solve.

Is there a ‘hook’ for the flight controls? (A place where you can drop in a flight control module. I can write my own.)

 

[Hielor]

Hielor, I checked with my brother who is a pilot to confirm what I thought – the trim tabs are really to balance the plane (front to back/left to right) do to the weight differentiation of the load (passengers/cargo) so that the plane flies straight and level without constant adjustments to the flight control surfaces.

Uh...no. That's not what trim tabs are for. At all. If that's actually what your brother believes, he's a terrible pilot and I hope he's not a professional. If he is, please let me know who he works for so I can never, ever, ever use that service.

Maybe if you're at a given speed and throttle setting, you could use trim tabs for that purpose, but if you change speeds and/or throttle settings, you should be using trim for something rather more important.

The root problem that trim tabs solve is this: control surfaces become more effective at higher speeds. So, the "neutral" position of the elevator might have you flying straight and level at a given speed, but at a higher speed, the horizontal stabilizer will be generating more (downward) lift due to the higher speed, and the airplane will pitch up. This is the main reason an airplane will naturally pitch up when you increase throttle. To offset this, you must either apply forward pressure on the control stick (thereby causing the elevator to provide enough upwards lift to counteract the increased downward lift from the horizontal stabilizer) or provide additional nose-down trim.

More simply: You're flying straight and level. You increase the throttle. The airplane will pitch up and start to climb. If you want to maintain altitude but increase speed, you need to counteract that pitching force, and you do that by trimming the airplane nose-down.

The opposite happens when decreasing throttle. The airplane will pitch down, and if you want to maintain altitude but decrease speed, you need to counteract that pitching force by trimming the airplane nose-up.

It does help though to fly the DGIV at a nice pitch. But, also, if you let go of the stick, a real plane will level off over a couple seconds but, the DGIV goes completely out of control. I just want something that doesn’t go into a spin that you can’t get out of.

Depends on the airplane, and if it was already trimmed to fly straight and level. As I mentioned above, if you increase or decrease throttle in an aircraft, it'll change pitch angle. If you're just taking off and accelerating, you're definitely going to need to use trim if you want to level off and let go of the stick--it won't just do it automagically. Both in real life and in the sim.

Ah, I realized that I would like the control surfaces to work like the trim (whether by joystick or keyboard)!

That's not how control surfaces work in real life, and I don't think the game should be changed to fit your fantasy world. If you want to fly that way, just fly using the trim keys instead of the normal control surface keys.

The other problem I have, is what someone else wrote in another post – you can use the joystick to angle the ailerons to put the DGIV in a 45 degree bank, but the plane doesn’t turn. It just rolls 45 degrees and keeps going in the same direction. I watched one of the tutorials ‘Stunts’ and the pilot was able to fly around, find the airport and land again on the runway. I still need practice to be able to do that, but I don’t think it should be that hard. It is not relaxing fighting every pitch and roll. (I’ll look into getting another, maybe better, joystick.)

That's because you actually need to pull back on the stick after banking in order to make the plane turn.

Is there a ‘hook’ for the flight controls? (A place where you can drop in a flight control module. I can write my own.)

You can write an addon to do whatever you want it to do.

 

[Mipada]

Well that explains his non-committal attitude when I asked him about trim. He didn't elaborate. You can see why he's my least favorite brother. He only flew for himself and he doesn't even do that anymore.
I was thinking of the flaps when a plane come in for a landing. They move a lever that sets the proper flat angle/shape. But, you're right. it's not how real planes work. I have trouble with simulators. When you can't feel the movement, you can't respond well to it. A slower turning or more lumbering ship would help make it easier to fly. I'll just have to practice more.
And, thanks for the input.

 

[jedidia]

if you let go of the stick, a real plane will level off over a couple seconds but, the DGIV goes completely out of control. I just want something that doesn’t go into a spin that you can’t get out of.

The DG isn't a plane... it's an overpowered rocket with wings on it. Of course it flies differently

 

[Mipada]

OK. Thanks.

 

[zerofay32]

The DG isn't a plane... it's an overpowered rocket with wings on it. Of course it flies differently

That and I wouldn't be surprised if the lift vector doesn't act correctly when you bank the DG. IIRC the DG (and DGIV) lift characteristics are handwavium anyways. Most of the 'lift' you get is from the overpowered rockets.

Real/accurately simed airplanes turn while banked because you're causing the lift component to act in a lateral direction (in reference to the ground). Normally the only nose up pressure is to make up for the less vertical lift that acts against gravity. The DGs are more like high power fighter aircraft (similar thrust to weight characteristics), its engines are so powerful that it doesn't rely on any lift generated my the wings. Just pure thrust like a conventional rocket, which makes is less realistic but easier to fly into orbit which was the intention of both DG and DGIV.

EDIT: Also talking about trim, I believe that trim in the DG and DGIV also trim the thrust vectoring on the engines. Another example of both ships' use of pure thrust vs. realistic aerodynamics (which of course is not their purpose).

 

[n122vu]

When you can't feel the movement, you can't respond well to it.

Unless you have a full-motion simulator, this is definitely a limitation that one must overcome. However, in doing so, you are actually benefiting yourself. It causes you to train yourself to rely on what is outside the cockpit window, and more importantly on your instruments. "I can't feel what the aircraft is doing, but what are the gauges telling me is going on? Does it match what I'm seeing outside the window?" Learning to reconcile those two things, along with suspension of disbelief regarding the DGIV's performance, will go a long way in helping you enjoy the sim even more.

 

[Ripley]

That, and the fact that real astronauts too (once in orbit) don't feel the movement, so...

 

[martins]

Not having come closer to a real-life cockpit than on my way past it to find my seat in the cabin, I can't speak with much authority on this topic, but here are a few physics-based observations:

Real/accurately simed airplanes turn while banked because you're causing the lift component to act in a lateral direction (in reference to the ground).

This is in fact how the DG works as well. In fact, the DG does turn when banking. However, since the thrust/lift ratio is so high, as noted above, the lateral lift component is small compared to the longitudinal thrust component, making the turn radius very large. You could go to a more conventional aircraft characteristic by reducing thrust and trimming for a low-speed equilibrium state. If you bank then, the lateral lift vector contribution will be larger, and the turn radius smaller.

Or, as Hielor mentioned, you pull back on the stick while banking. This will increase the angle of attack, and thus the lift. If you do that at high speed, you need to keep an eye on the wing load, if you want to avoid your wings taking off on their own.

Note that the DG has to work across a wider velocity range than most aircraft, which means that its lift characteristics are a compromise for a wide airspeed range. At low speeds, the control surfaces at a neutral position won't produce enough lift for level flight, while at hypersonic speeds excessive lift becomes a problem, unless you have climbed out of the atmosphere by then. So if you want to fly a hands-off-stick ascent, you may have to adjust the trim constantly as your speed increases.

Another personal observation: if the aircraft is not at equilibrium when you try to trim it, you may find yourself chasing the attitude with your trimwheel through an oscillation cycle (applying pitch down trim while the nose is pitching up, then pitch up trim when it starts pitching down), leading to a forced oscillation with actually increasing amplitude. The DG's eigenfrequency in pitch is quite low, mainly because it's designed fairly unstable (to allow high AOA), so this could easily happen. The technique to apply trim while at the same time relaxing the stick to keep the aircraft at its equilibrium state is therefore very useful.

EDIT: Also talking about trim, I believe that trim in the DG and DGIV also trim the thrust vectoring on the engines. Another example of both ships' use of pure thrust vs. realistic aerodynamics (which of course is not their purpose).

Not quite. Thrust vectoring is not linked to trim, but you can link it to your pitch, bank and yaw commands. In fact, you can disable the aero control surfaces altogether and control attitude with thrust vectoring only. This may be a good strategy at hypersonic speeds where even small control surface deflections might produce excessive wing loads.

 

[zerofay32]

Thanks Martin.

 

[Mipada]

Success!

SUCCESS! I made it into orbit on fly-by-wire mode (without auto-pilot). I used the Level Horizon AP to control the rolling. Ok, I guess I did use some AP. I put the hover engines on full, yawed right to 42 degrees, put main engines on full, after a few seconds, turned off the hover and then put on the Level Horizon AP and tried to keep a 40 degree incline.

I was also able to work out an Ascent Profile that worked. Tex’s Video Tutorial: DG4 to ISS (https://vimeo.com/4718661) is awesome but he skips that part and so leaves many with a hole in their knowledge about how to achieve orbit. (And if he re-redoes his video – remember to open the nose cone! – when you open the retro doors.)

I watched the DGIV Ascent tutorial (and had to keep the ship from rolling) and noticed that while the setting was at 40 degrees, the vector indicator was not anywhere close to that. And, it started dropping as it usually does but, the angle was sufficient to get it into orbit.

Alt (k) Setting (d) Actual (d)
000 65 65
020 65 65
040 55 65
060 40 60
080 40 50
100 40 40
120 40 30
140 40 20
160 40 10
180 40 05
200 20 05
220 10 00
240 00 00

http://lotrolordsofbrotherhood.webs.com/photos/Random-Pics/Ascent Profile.bmp
I hope the link to a picture of the spreadsheet works.

As you can see, only at about 200K was I able to level off. The vector indicator was over 0 degrees so, I wasn’t concerned about loosing orbit. This, actually, was my best orbit entry ever!

Note that the DG has to work across a wider velocity range than most aircraft, which means that its lift characteristics are a compromise for a wide airspeed range. At low speeds, the control surfaces at a neutral position won't produce enough lift for level flight, while at hypersonic speeds excessive lift becomes a problem, unless you have climbed out of the atmosphere by then. So if you want to fly a hands-off-stick ascent, you may have to adjust the trim constantly as your speed increases.

Real/accurately simed airplanes turn while banked because you're causing the lift component to act in a lateral direction (in reference to the ground). Normally the only nose up pressure is to make up for the less vertical lift that acts against gravity. The DGs are more like high power fighter aircraft (similar thrust to weight characteristics), its engines are so powerful that it doesn't rely on any lift generated my the wings. Just pure thrust like a conventional rocket, which makes is less realistic but easier to fly into orbit which was the intention of both DG and DGIV.

It’s a simulator – it can be made to do what ever you want it to do. The DGIV has airfoils and an atmospheric flight mode – they may as well add more of an up-vector while yawing.

Thanks for your input. A lot of people have been asking for numbers and I have not seen them anywhere. I hope this becomes sticky-ed or something.

---------- Post added at 05:43 AM ---------- Previous post was at 05:07 AM ----------

Alt (k) Setting (d) Actual (d)
000 ________65 _____65
020 ________65 _____65
040 ________55 _____65
060 ________40 _____60
080 ________40 _____50
100 ________40 _____40
120 ________40 _____30
140 ________40 _____20
160 ________40 _____10
180 ________40 _____05
200 ________20 _____05
220 ________10 _____00
240 ________00 _____00

 

[Hielor]

It’s a simulator – it can be made to do what ever you want it to do. The DGIV has airfoils and an atmospheric flight mode – they may as well add more of an up-vector while yawing.

The point was that if they did add more of an up-vector while banking (yaw is something different), the plane would be uncontrollable at high speeds due to too much lift.