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XyZspineZyX
08-12-2003, 12:24 PM
Note: I posted this in the general discussion forum, but it remained unnoticed. So, I've posted here, because it's about FM, and I think it can be of interest.


This is something I read about I-16's fighting in the Spanish Civil War:

It seems that, due to the reduced length of the plane and inherent unstability, diving controls tended to get inverted at high diving speeds, many learning pilots losing their lives when trying to recover from a steep dive. They simply pulled the stick back and back, when it was surprisingly necessary to push it forward.

I think it's true, for it was stated by some acclaimed soviet and spanish aces of I-16 during that bloody conflict.

Is this implemented in Il-2 FB I-16 flight model? I have not experienced it. If not, I think that it would be interesting to take a look on it.

You can read about it in Cpt. Lacalle's SCW memoir book, but it could be difficult to find.

Thank you.



- Dux Corvan -

"It doesn't matter how good you are: In a crowded dogfight even the most experienced ace can be downed by a rookie; so, surviving an air war is just a matter of luck. However, an agressive attitude is the only one that gives you a chance to live, for runners are generally chased to death."
(Captain Lacalle, ace of the Republican Air Force during the Spanish Civil War.)

- Dux Corvan -

"It doesn't matter how good you are: In a crowded dogfight even the most experienced ace can be downed by a rookie; so, surviving an air war is just a matter of luck. However, an agressive attitude is the only one that gives you a chance to live, for runners are generally chased to death."
(Captain Lacalle, ace of the Republican Air Force during the Spanish Civil War.)

XyZspineZyX
08-12-2003, 12:24 PM
Note: I posted this in the general discussion forum, but it remained unnoticed. So, I've posted here, because it's about FM, and I think it can be of interest.


This is something I read about I-16's fighting in the Spanish Civil War:

It seems that, due to the reduced length of the plane and inherent unstability, diving controls tended to get inverted at high diving speeds, many learning pilots losing their lives when trying to recover from a steep dive. They simply pulled the stick back and back, when it was surprisingly necessary to push it forward.

I think it's true, for it was stated by some acclaimed soviet and spanish aces of I-16 during that bloody conflict.

Is this implemented in Il-2 FB I-16 flight model? I have not experienced it. If not, I think that it would be interesting to take a look on it.

You can read about it in Cpt. Lacalle's SCW memoir book, but it could be difficult to find.

Thank you.



- Dux Corvan -

"It doesn't matter how good you are: In a crowded dogfight even the most experienced ace can be downed by a rookie; so, surviving an air war is just a matter of luck. However, an agressive attitude is the only one that gives you a chance to live, for runners are generally chased to death."
(Captain Lacalle, ace of the Republican Air Force during the Spanish Civil War.)

- Dux Corvan -

"It doesn't matter how good you are: In a crowded dogfight even the most experienced ace can be downed by a rookie; so, surviving an air war is just a matter of luck. However, an agressive attitude is the only one that gives you a chance to live, for runners are generally chased to death."
(Captain Lacalle, ace of the Republican Air Force during the Spanish Civil War.)

XyZspineZyX
08-21-2003, 09:58 AM
bump

- Dux Corvan -

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XyZspineZyX
08-21-2003, 03:11 PM
I've never seen this or heard about it, I'll check into it.

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XyZspineZyX
08-21-2003, 07:38 PM
Diving controls? you mean the elevator?


Getting it inverted would be pretty impossible. Something should bes seriously wrecked by that.

Technically impossible I think. ALtough I'm not familliar with the I-16's elevator. (never heard of diving controls)

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2 For with what judgment ye judge, ye
shall be judged: and with what
measure ye mete, it shall be
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XyZspineZyX
08-21-2003, 08:09 PM
No, I don't mean physically inverted. You know, the surfaces reacted the same: stick forward, elevator down, and viceversa. But the effect on flying was the contrary way. It seems that the I-16 fuselage was so short that with high surface pressures, elevators acted like in a canard plane, raising up the nose when the elevator surface was down.

- Dux Corvan -

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XyZspineZyX
08-21-2003, 08:11 PM
Ah, you can find diving controls... in a sub! /i/smilies/16x16_smiley-happy.gif

Sorry for the mistake. I'm not a born-English-speaker. /i/smilies/16x16_smiley-wink.gif

- Dux Corvan -

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XyZspineZyX
08-21-2003, 08:13 PM
yep thats correct/i/smilies/16x16_smiley-happy.gif

XyZspineZyX
08-21-2003, 08:42 PM
This sort of thing could happen to a lot of aircraft when they started approaching the speed of sound.

While the cause for it may vary from aircraft to aircraft, control reversals are fairly well documented throughout history.

For a more modern example, the reason many jets and airliners have spoilers on the wings has more to do with turning than simply wanting to come down quickly (they also help a lot with landing, so you don't have to throttle back, but that's a different topic).

At high speeds, the long, thin wings of an airliner will tend to flex and bend when the ailerons are used. If enough deflection is input at high enough speeds, the aileron will cause a twisting action in the wing itself, so that the entire wing then acts like a control surface moving in the opposite direction of the ailerons.

So while the aileron may be inputting a left roll, the wings twist enough to overpower it and create a net right roll effect.

To help prevent this many jets will use spoilers (or a combination of spoilers and ailerons) to turn at high speeds instead.

The idea behind this is that ailerons will increase the lift on the wing, causing one to rise and one to "rise down" (go down). This extra lift turns the plane but also causes the warping. However, if you come at the same concept from the other direction you can overcome the problem.

With spoilers for turning, instead of increasing the lift on the wing you want to raise, you use spoilers to kill some of the lift on the wing you want to lower.

As a result you get the turn you want, tend to produce "proverse" rather than adverse yaw, and don't have to worry about the control reversal issues.

In any case, I'm not sure if this sort of thing is modeled in FB, but I have noticed compressibility effects in the form of unresponsive/fluttering controls. If that's an accurate result of compressibility in the I-16 it would be nice to see it in there, if it's possible to do.

I liked the surprise of the BI-1 when it suddenly nosed over and started heading for the ground the first time I ever took it too fast. Fortunately it still had plenty of roll authority though, so going inverted so it pushed itself into a climb untill the speed bled off wasn't a problem. Really caught me off guard the first time it happened though. /i/smilies/16x16_smiley-happy.gif

XyZspineZyX
08-21-2003, 08:50 PM
Thank you, BinaryFalcon. A comprehensive explanation.

I'd like to see it in I-16 FM. Just to feel the surprise. /i/smilies/16x16_smiley-happy.gif

- Dux Corvan -

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XyZspineZyX
08-22-2003, 01:18 AM
transonic flight and compressibility in an I16 ???


sure you guys are not thinking of the F16 ???

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XyZspineZyX
08-22-2003, 03:32 AM
WTE_Galway wrote:
- transonic flight and compressibility in an I16 ???
-
-
- sure you guys are not thinking of the F16 ???
-
It may not need going this fast for it to happen. IF the vertical stablizers are not strong enough, the elevators act as trim tabs actually, then what described above happens. So I guess it's the I16's inferior structural strngth.

Someone's posted before that NASA is doing experimants on an F-18. They give it more flexible wings and use opposite aileron to roll. I'll post if I find that info again.

XyZspineZyX
08-22-2003, 03:49 AM
Found that info!

http://www1.nasa.gov/news/highlights/aeroelastic_wing.html

http://www.dfrc.nasa.gov/Gallery/Photo/AAW/HTML/EC03-0039-14.html

XyZspineZyX
08-22-2003, 04:04 PM
DuxCorvan wrote:
- No, I don't mean physically inverted. You know, the
- surfaces reacted the same: stick forward, elevator
- down, and viceversa. But the effect on flying was
- the contrary way. It seems that the I-16 fuselage
- was so short that with high surface pressures,
- elevators acted like in a canard plane, raising up
- the nose when the elevator surface was down.
-
-- Dux Corvan -
-
Ow, glad to hear that http://ubbxforums.ubi.com/infopop/emoticons/icon_razz.gif It might be something like this: when you push the stick, everyone expects the plane to go down. By going down, you gain some airspeed and the airspeed generates more lift, wich causes the airplane to go up.

It just might be like this but, I don't know.

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2 For with what judgment ye judge, ye
shall be judged: and with what
measure ye mete, it shall be
measured to you again.

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XyZspineZyX
08-22-2003, 05:29 PM
Platypus_1.JaVA wrote:
-
It might be something like
- this: when you push the stick, everyone expects the
- plane to go down. By going down, you gain some
- airspeed and the airspeed generates more lift, wich
- causes the airplane to go up.

No, it's not that, because when you pull the stick, everyone expects the plane to recover, but it goes down even more. Just reversed. As if you inverted the Y axis in your joystick./i/smilies/16x16_smiley-surprised.gif


- Dux Corvan -

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XyZspineZyX
08-23-2003, 09:58 PM
Yeah, and it works the other way around. By pulling your stick, you loose airspeed and you'll loose lift. Anyways, that's my explanation.

DuxCorvan wrote:
- Platypus_1.JaVA wrote:
--
- It might be something like
-
-- this: when you push the stick, everyone expects the
-- plane to go down. By going down, you gain some
-- airspeed and the airspeed generates more lift, wich
-- causes the airplane to go up.
-
- No, it's not that, because when you pull the stick,
- everyone expects the plane to recover, but it goes
- down even more. Just reversed. As if you inverted
- the Y axis in your joystick./i/smilies/16x16_smiley-surprised.gif
-
-
-
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2 For with what judgment ye judge, ye
shall be judged: and with what
measure ye mete, it shall be
measured to you again.

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XyZspineZyX
08-23-2003, 10:55 PM
Compressability effects set in on different aircraft at different speeds. The Zero, for example, begane experiencing compressability at only around 300 mph IAS, while the P-47 took around 500mph to start having problems.

Anyways, the effects of compression and high sub mach flight are not modelled in Il-2 to my knowledge. The heavying up control survaces are just from standard increasing of aerodynamic pressure.

Harry Voyager

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XyZspineZyX
08-24-2003, 01:54 PM
Platypus_1.JaVA wrote:
- Yeah, and it works the other way around. By pulling
- your stick, you loose airspeed and you'll loose
- lift. Anyways, that's my explanation.
-

Noooooo.....! (sigh) /i/smilies/16x16_smiley-happy.gif

You never lose speed. By pulling the stick, the nose NEVER rises, the nose DOWNS... and you gain more and more speed... and lift... but you are heading the ground. The fact is that the controls acted the contrary way... that simple. /i/smilies/16x16_smiley-very-happy.gif

- Dux Corvan -

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XyZspineZyX
08-24-2003, 03:11 PM
DuxCorvan wrote:

- Noooooo.....! (sigh) /i/smilies/16x16_smiley-happy.gif
-
- You never lose speed. By pulling the stick, the nose
- NEVER rises, the nose DOWNS... and you gain more and
- more speed... and lift... but you are heading the
- ground. The fact is that the controls acted the
- contrary way... that simple.
Nooooooo.....!

You never gain more lift. By pulling that stick and pitching downwards, you gain negative lift, not more lift.

XyZspineZyX
08-24-2003, 03:31 PM
Yeeees! You are right! (Now you could see me slapping my head) /i/smilies/16x16_smiley-surprised.gif

What I tried to say is that the dive is not resulting from a loss of speed, and that speed just makes the trouble bigger. /i/smilies/16x16_smiley-happy.gif

- Dux Corvan -

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XyZspineZyX
08-24-2003, 07:09 PM
Control reversal has a few faces, and the one that usually impacts piston aircraft is at low speed high angle of attack flight attitudes. This would not affect the elevator however. What happens is that the aircraft is just a few knots above stall speed (usually in the landing configuration) and the pilot uses a little too much aileron, or does not lead with the rudder enough to make attitude adjustments (as many vintage taildraggers require), such as after a wing dips due to turbulence. In order to lift the dropping wing the aileron must deflect downwards, which increases lift, but also increases drag and will cause a deceleration of that wing and under the right circumstances will cause the already dropping wing to stall, and drop further, in effect the ailerons have the opposite effect on aircraft attitude that they should.
I have an acquaintance who flies a GeeBee, given that he is the only person flying this type of aircraft he was in effect a test pilot, and he discovered that this aircraft had a fairly aggressive aileron reversal when landing nose high (as in a 3 point landing) and now he lands using wheel landings only!





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Message Edited on 08/24/0310:14AM by TX-EcoDragon

XyZspineZyX
08-24-2003, 08:06 PM
The BI-1 does this in the game. Dive from a decent altitude or even a long shallow dive at full throttle will cause this effect. Speed is high though.

Try it

/i/smilies/16x16_smiley-happy.gif

It's only funny til someone loses an eye....then it's hilarious

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XyZspineZyX
08-24-2003, 08:43 PM
Well, I'll tell the story. Captain Lacalle was the commander of the I-15 Fighter Groups in the FARE (Spanish Republican Air Force). He accompanied a bunch of rookie pilots to the USSR, where they were to learn fighter tactics and flying in an I-16. While he was there he witnessed a common accident. One Russian instructor and a novice Spanish pilot were flying in a two-seat conversion I-16, and the instructor let the rookie fly on his own.

Suddenly, the rookie started a dive, and he was so nervous that he didn't left the stick, so that his instructor could take control. The plane went down faster and faster and finally hit the ground. Both killed.

Another instructor told Lacalle that it was a common accident for rookies, and explained him the issue that I've told in the first post.

Lacalle wanted to test it himself, and, although he was more acquainted to biplanes, he took for a ride, and tried steep diving with the plane. Fortunately, he had been prevented and reacted the right way when the elevator controls got reversed.

Anyway, the Russian political comissaires accused the Spanish pilots of having killed an instructor, and the ambient got so bittered that Lacalle asked permission for him and his pupils to come back Spain.

That's the story, and it's quite believable, for I've read Lacalle's memoirs and he was a modest man, far from being a liar. In fact, he tries to destroy the myth of the fighter pilot as a man above the others. And he got more that 30 kills flying Ni.62, Hawker Furies and I-15s, most of them against technically superior aircraft!

I hope you've found it interesting. /i/smilies/16x16_smiley-happy.gif

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XyZspineZyX
08-24-2003, 09:36 PM
Compressability effects are not standard control problems such as what you described with the Gee-Bee.

From what I understand, when one is aproching the speed of sound air begins to behaves as if it were a liquid*, rather than a gas. More specifically, it reaches the limit to which it can be compressed. This causes large problems for conventional control surfaces, as they depend heavily on compressing, and decompressing airflows, in order to change an aircraft's patch of travel. Once they can no longer compress airflow, they begin to do very strange things.

Supersonic jets do not use elevators; their entire tailplane moves in order to pitch the aircraft. In fact, many supersonic jets no longer use ailerons for supersonic roll control either; they use the the tailplane to roll the aircraft, when super sonic.

I also understand that transonic and super sonic airfoils are inverted. They are flat on the top, and curved on the bottom. I do not know why, just that they are. Several modern Jet fighters use leading edge slats, now just called leading edge flaps to configure the wing for different flight envelopes. In subsonic flight, they tilt down. In supersonic flight, they tilt *up*. Again, I do not know why. All I know is that air behaves differently when you are travelling faster than the speed of sound.

Harry Voyager

*I know someone is going to ask, well then, why aren't super sonic jets shaped like boats? Well, in their own way, they already are. However, they are designed to fly through a fluid of radically different viscosity and density. At least, that is my understanding of it.

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XyZspineZyX
08-25-2003, 03:48 AM
"Comrad, if you pull on stick and nose goes up, keep pulling, if you want to go up. If you push on stick and nose goes down, keep pushing if you want to go down.

If you pull on stick and nose goes down, stop pulling and start pushing if you want to go up, not down. If you want to go down keep pulling and don't start pushing. But not if you want to go up. Then you must push.

And if you push on stick and nose goes up, stop pushing and start pulling if you want to go down, not up. If you want to go up keep pushing and don't start pulling. But not if you want to go down. Then you must pull."

Says the appropriate section of the VVS I-16 manual, used during the training of the newb Soviet I-16 fighter jocks at the Eastern front during WWII.

No, really!

Oh, and it also says: "After emergency landing less than 500 Miles away from homebase, don't call for help, just keep pushing also.."

*Disclaimer: since this is total nonsense anyway, no feelings of any Ex-VVS fighter jocks were hurt during the making of this short mockery.. not intentionally, anyway*

/i/smilies/16x16_smiley-wink.gif