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View Full Version : may the force be with you, or "questions about stick forces!"



XyZspineZyX
06-16-2003, 01:26 PM
lately the (in game) FW190 elevator problem was often compared to the ME109 "stick forces" in a dive. Then I found a remark that one of the more important improvements of the L5FN was the reducement of stick forces.

this made me curious and I have some questions

1. someone knows the values for the planes in FB?

2. how change higher stick forces the stearing of a plane in real?
-slower movement of the stick?
-speedlimits for dive?
-how long could a well trained pilot pull high g's?

I've read stick forces could also work the other way round, some airplanes where not able to do high speed dives because the pilot was not able to push the stick enough to keep the nose down.

3. what planes had this "problem"?

4. how work stick forces in FB?
what I (think I) know:
-less elevator deflection
-no complete lock
-no pilot fatigue

from my personal impression the very early airplanes like 109E, I-16 ... and even the bombers behave very well in high speed dives, some even better than late war fighters.

maybe this "high speed effects" could/should be modelled with more deep in a future sim?

quiet_man

sorry for the title, couldn't resist /i/smilies/16x16_smiley-wink.gif

XyZspineZyX
06-16-2003, 01:26 PM
lately the (in game) FW190 elevator problem was often compared to the ME109 "stick forces" in a dive. Then I found a remark that one of the more important improvements of the L5FN was the reducement of stick forces.

this made me curious and I have some questions

1. someone knows the values for the planes in FB?

2. how change higher stick forces the stearing of a plane in real?
-slower movement of the stick?
-speedlimits for dive?
-how long could a well trained pilot pull high g's?

I've read stick forces could also work the other way round, some airplanes where not able to do high speed dives because the pilot was not able to push the stick enough to keep the nose down.

3. what planes had this "problem"?

4. how work stick forces in FB?
what I (think I) know:
-less elevator deflection
-no complete lock
-no pilot fatigue

from my personal impression the very early airplanes like 109E, I-16 ... and even the bombers behave very well in high speed dives, some even better than late war fighters.

maybe this "high speed effects" could/should be modelled with more deep in a future sim?

quiet_man

sorry for the title, couldn't resist /i/smilies/16x16_smiley-wink.gif

XyZspineZyX
06-16-2003, 01:40 PM
In actual aircraft the issue of control surface forces is subjective: it depends on which aircraft

for example: the Zero had a huge amount of aileron on the wing. Great for low speed maneuverability. As speed increased, that huge aileron got harder and harder to use.

In other aircraft, high speed dives could lead to fatal, non-recoverable situations were the usual control inputs would get reversed, or even fail to influence the aircraft's attitude at all

Gs have less to do with training, and more to do with human endurance. the net result of high G was loss of vision, and then loss of consciousness. Training would not counteract the loss of blood from the head and it's collection in the legs. Similarly, under negative G the blood rushes to the head...the solution was anti-G suits, which inflated air bladders that pressed against the body, restricting the flow of blood to either extreme in principle. The proper use of the anti-G suit would take some training.

P-47s had a type of control surface problems from a dive, called "mush", where it would sort of wallow out of a dive, losing more altitude than seems regular, and like the P-38, could also experience "compressibility" were a dive might be unrecoverable. This could involve the nose of the aircraft going past the vertical, 'tucked in', and that could make even bailing out of the plane impossible- high pressure air spilling back into the cockpit might hold you in. Sort of like when you see a convertible drive by, and the driver's hair is blowing forwards. You'd expect it to be blowing back, right? But the air spills over the windscreen, and goes to low pressure, which is the passenger compartment of the car, or the cockpit of an airplane, which means the air rushes forward.

XyZspineZyX
06-17-2003, 12:03 PM
BBB462cid wrote:
- In actual aircraft the issue of control surface
- forces is subjective: it depends on which aircraft
-
- for example: the Zero had a huge amount of aileron
- on the wing. Great for low speed maneuverability. As
- speed increased, that huge aileron got harder and
- harder to use.
-
- In other aircraft, high speed dives could lead to
- fatal, non-recoverable situations were the usual
- control inputs would get reversed, or even fail to
- influence the aircraft's attitude at all


is such a thing modelled in IL2?


-
- Gs have less to do with training, and more to do
- with human endurance. the net result of high G was
- loss of vision, and then loss of consciousness.
- Training would not counteract the loss of blood from
- the head and it's collection in the legs. Similarly,
- under negative G the blood rushes to the head...the
- solution was anti-G suits, which inflated air
- bladders that pressed against the body, restricting
- the flow of blood to either extreme in principle.
- The proper use of the anti-G suit would take some
- training.


oh, I didn't thought of this effects. I found a quote from an russian ace flying the Lagg3
he was able to outturn the 109 by "pulling on the stick with full strenght, like we had trained" nothing about blackout.

how long can a pilot pull the stick with full strength?
I heard from an professional fighting trainer that untrained people can hold full strength for about 30 seconds, while trained people can hold it for about 3 minutes.

maybe that's why WWII eastern airfights lasted only about 5 minutes? if the Lagg3 got into firing position in the first few minutes he won, if not ...


-
- P-47s had a type of control surface problems from a
- dive, called "mush", where it would sort of wallow
- out of a dive, losing more altitude than seems
- regular, and like the P-38, could also experience
- "compressibility" were a dive might be
- unrecoverable. This could involve the nose of the
- aircraft going past the vertical, 'tucked in', and
- that could make even bailing out of the plane
- impossible- high pressure air spilling back into the
- cockpit might hold you in. Sort of like when you see
- a convertible drive by, and the driver's hair is
- blowing forwards. You'd expect it to be blowing
- back, right? But the air spills over the windscreen,
- and goes to low pressure, which is the passenger
- compartment of the car, or the cockpit of an
- airplane, which means the air rushes forward.
-
-


this sounds like an very important factor.
Maybe more important than blackout for early planes .

quiet_man

XyZspineZyX
06-17-2003, 12:34 PM
Some way or another the effect of stick stiffening is there in IL-2, and IL-2:FB. Some planes aren't that much affected (Yaks for example) while others become very sluggish in their response at high speed (LaGGs for example.) Presumably this is because you're not "string enough" to make full control surface deflection at that speed.
_
/Bjorn.

XyZspineZyX
06-17-2003, 12:43 PM
you should bring this to GD

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter


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XyZspineZyX
06-17-2003, 02:59 PM
I don't know the values for the stickforces, but you can cancel out any stickforces by simply applying (elevator) trim to counter the stickforces.

When you do that, the stickforces are reduced to zero, regardless of the speed you're flying the plane. That was so in IL2, that is so in FB.


/i/smilies/16x16_smiley-happy.gif

XyZspineZyX
06-18-2003, 03:32 AM
Perhaps LaGG pilots were trained to pull hard in preparation for the eventual blackout because they were trained to expect it?? I'd say that any pilot with the pluck of a weevil in a biscuit would know to yank the stick hard to tighten his turn...heck, I knew that much in 'Aces over the pacific:" http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

XyZspineZyX
06-18-2003, 01:46 PM
quiet_man wrote:

- 4. how work stick forces in FB?
- what I (think I) know:
--less elevator deflection
--no complete lock
--no pilot fatigue

Same as in IL2.

When you pull on your joystick the amount of pull is taken as how much strength the pilot is using to pull on the model of the stick in the model of the plane. It is not 1 for 1 except when on the ground stopped depending on your settings.

Settings:
There is a stick sensitivity settings as part of the hardware settings. You choose one axis (pitch up and down, roll left and right, rudder left and right) and then there is sliders from 0 to 100 in 10's. Imagine that if all sliders are at 100, all the way up, that the 10% position will get a full 10% of the pilots strength when you pull your computer stick back 10% of the way. And so it goes for all the sliders with the far right slider giving pilot strength response to your full stick move... if you set that slider at 90 then he only uses 90% of his power.

The default slider positions are set much less near to center to make for a delicate strength used for sensitive aiming. But that also means that trim changes equal a good bit of the weak strength of near center stick moves, you have to move the stick farther to equal one step of trim when your sliders are low at the center than when they are high. It pays to write down what you have and then experiment with other settings -- they may not match the stick and computer you have anyway.

How it works in flying:
As you speed increases, there is forces on the model so forces on the model stick. You do not move the model stick directly. You apply strength to the model stick by moving your computer stick. How much depends on those settings. As you go faster and faster the pilot has not the strength to move the stick so far. If your settings are too low then you will feel the plane has not enough response and if they are too high then you may have a hard time keeping stable.
No matter how high you make the settings, there will still be a point where you cannot get the model stick to go as far as you want at very high speeds. This happens quicker in some planes than other, this is as history shows and the Bf109 is a very famous example as are others. The FW should have good control for a plane of its time but again, if you have those sliders set low then you are limiting what your pilot can do and it is not the flight model or plane model that is making the limit. Low sliders in the left to high sliders at the right... your main strength response will come quickly all at the end of your pull so slow down as you get the stick near to full. I ran my pitch/elevator sliders at all 100's and got a better overall control on my system, it it good to experiment! (Thank you DNMY!)


Neal