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Rab03
02-06-2007, 09:02 AM
To start with thanks for Oleg & Team and community for developing currently the best sim ever and sustaining unparalleled effort of constant upgrade and improvement of their product.

However, I have several personal observations not based on actual flight data (have this on mind) but on understanding for physics and aerodynamics (have M.Sc. in ME, also have in mind).
Main issues I have with this beautiful sim, which start to bother me more and more with time are:
1. Loss of altitude when banking an aircraft.
2. Use of rudder when turning.
3. LOss of speed AND altitude when reducing throttle.
4. Low speed flight at high angles of attack.

Explanation:
1. When you bank an aircraft, you are actually reducing vertical component of lift vector, which counters Earth's gravity. Having this in mind, when this component falls below gravity vector value, you end up with downward acceleration. Consequently, if you bank an aircraft 90 deegres (and don't use rudder in opposite direction) aircraft actually falls like a brick (losing altitude with downward acceleration of approx. 9,81 m per square second). The overall feel in game simply differs from this.
2. Having previous reason in mind, shouldn't the proper procedure for turning include banking and rudder in opposite direction for compensating altitude loss. Should AI almost always apply rudder in the same direction of the banking? Is this right? Many years ago, while I was a kid, I read in some flying school's manuals about just the opposite (yes, I know WWII fighters are different than todays sport aircraft, but the physics is the same).
3. Having read Pierre Closterman's The Grand Circus (which is a selection of texts from his war diary) one detail he described caught my attention. He stated that they flew Spitfires over channel at a very low level - several meters above water and that during approach to France they had to switch tanks with a valve in cockpit. If, he said, there was a bubble somewhere in the valve or in pipes, he would have experienced caughing of an engine, instant loss of airspeed and height and would in almost split second crash to the sea. Currently, loss of airspeed and height when you lose an engine feels insignificant, ie. you can even climb and later crash land any given airplane in the sim, although instructions given to Luftwaffe pilots for Fw-190 (if I recall correctly) explicitly state that if you lose an engine (in terms of power), you should not try to crash land, but bail out (!), while there are many evidence showing that Bf-109 could actually belly land with little trouble.
4. I feel that when flying at high angles of attack and low speed you should also lose altitude more significantly. To differently put it, when you dive to an airport at low speed and suddenly pull up nose above horizon, you shouldn't start climbing, but level up or continue to drop (depending on the aircraft type, speed and how much you pull your stick) and lose airspeed, which can result in realy nice landing, or crash if you miscalculated speed and height. Are this elements of the sim modelled right? Is flight at high angles of attack limited to speeds below 150kmph?

That's it from me. Cause I'm a little low on free time, please don't shoot back questions at me and expect me to answer promptly. I posted this in hope some constructive thinking would come out from it and that further (and final) refinements of Il-2 series will follow.

Clear skies to all!

Rab03
02-06-2007, 09:02 AM
To start with thanks for Oleg & Team and community for developing currently the best sim ever and sustaining unparalleled effort of constant upgrade and improvement of their product.

However, I have several personal observations not based on actual flight data (have this on mind) but on understanding for physics and aerodynamics (have M.Sc. in ME, also have in mind).
Main issues I have with this beautiful sim, which start to bother me more and more with time are:
1. Loss of altitude when banking an aircraft.
2. Use of rudder when turning.
3. LOss of speed AND altitude when reducing throttle.
4. Low speed flight at high angles of attack.

Explanation:
1. When you bank an aircraft, you are actually reducing vertical component of lift vector, which counters Earth's gravity. Having this in mind, when this component falls below gravity vector value, you end up with downward acceleration. Consequently, if you bank an aircraft 90 deegres (and don't use rudder in opposite direction) aircraft actually falls like a brick (losing altitude with downward acceleration of approx. 9,81 m per square second). The overall feel in game simply differs from this.
2. Having previous reason in mind, shouldn't the proper procedure for turning include banking and rudder in opposite direction for compensating altitude loss. Should AI almost always apply rudder in the same direction of the banking? Is this right? Many years ago, while I was a kid, I read in some flying school's manuals about just the opposite (yes, I know WWII fighters are different than todays sport aircraft, but the physics is the same).
3. Having read Pierre Closterman's The Grand Circus (which is a selection of texts from his war diary) one detail he described caught my attention. He stated that they flew Spitfires over channel at a very low level - several meters above water and that during approach to France they had to switch tanks with a valve in cockpit. If, he said, there was a bubble somewhere in the valve or in pipes, he would have experienced caughing of an engine, instant loss of airspeed and height and would in almost split second crash to the sea. Currently, loss of airspeed and height when you lose an engine feels insignificant, ie. you can even climb and later crash land any given airplane in the sim, although instructions given to Luftwaffe pilots for Fw-190 (if I recall correctly) explicitly state that if you lose an engine (in terms of power), you should not try to crash land, but bail out (!), while there are many evidence showing that Bf-109 could actually belly land with little trouble.
4. I feel that when flying at high angles of attack and low speed you should also lose altitude more significantly. To differently put it, when you dive to an airport at low speed and suddenly pull up nose above horizon, you shouldn't start climbing, but level up or continue to drop (depending on the aircraft type, speed and how much you pull your stick) and lose airspeed, which can result in realy nice landing, or crash if you miscalculated speed and height. Are this elements of the sim modelled right? Is flight at high angles of attack limited to speeds below 150kmph?

That's it from me. Cause I'm a little low on free time, please don't shoot back questions at me and expect me to answer promptly. I posted this in hope some constructive thinking would come out from it and that further (and final) refinements of Il-2 series will follow.

Clear skies to all!

Rab03
02-06-2007, 09:14 AM
One more thing I've forgotten to mention.

Many times I have noticed a bit interesting bug in Fw-190 damage model: when you get shot in the wings (and nowhere else), there is a message which says you lost your machinegun (!) and really, one of the machingeguns stops working (they are in front of cockpit, not in the wings, right?). Vice versa, when I was once shot in the engine cowl, message says cannon damaged, and cannon stops working. How? In Fw-190, two machineguns and their ammo are in the engine cowl, while cannons and their ammo are in the wings. This should be addressed and corrected.

BTW, since I haven't purchased 1946 yet, so I am not aware if this has been corrected.

EDCF_Rama
02-06-2007, 10:35 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rab03:
1. When you bank an aircraft, you are actually reducing vertical component of lift vector, which counters Earth's gravity. Having this in mind, when this component falls below gravity vector value, you end up with downward acceleration. Consequently, if you bank an aircraft 90 deegres (and don't use rudder in opposite direction) aircraft actually falls like a brick (losing altitude with downward acceleration of approx. 9,81 m per square second). The overall feel in game simply differs from this. </div></BLOCKQUOTE>

Simply because The case were no part of your plane don't produce lift doesn't exist.
The plane body and the tail generate some lift (for example a French Alphajet can fly level on side flying at 380 knts without lossing altitude).
Moreoever, for WWII planes, the wings angle makes it impossible to have both wing at 90?... so you have allways at least one wing giving a little lift.
With this in mind, you allways have a speed at which the lift generated is sufficient to stay level.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">2. Having previous reason in mind, shouldn't the proper procedure for turning include banking and rudder in opposite direction for compensating altitude loss. Should AI almost always apply rudder in the same direction of the banking? Is this right? Many years ago, while I was a kid, I read in some flying school's manuals about just the opposite (yes, I know WWII fighters are different than todays sport aircraft, but the physics is the same). </div></BLOCKQUOTE>

Your first reason is wrong, and you probably don't remember well what you did read in the flying school's manual.
When you turn, you need to give some foot inside the turn, to correct the induced yaw (the external wing going faster produce more lift and more drag, who tend to twist the plane nose toward the outside of the turn).
In order to keep level during turn, you use the elvator, not the rudder.
This is only if you try a prolonged turn near 90? that you need some ruder to fly level (as you would do if you fly on the side in a straight fly)... but then you should be very carefull with possible stall.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">3. Having read Pierre Closterman's The Grand Circus (which is a selection of texts from his war diary) one detail he described caught my attention. He stated that they flew Spitfires over channel at a very low level - several meters above water and that during approach to France they had to switch tanks with a valve in cockpit. If, he said, there was a bubble somewhere in the valve or in pipes, he would have experienced caughing of an engine, instant loss of airspeed and height and would in almost split second crash to the sea. Currently, loss of airspeed and height when you lose an engine feels insignificant, ie. you can even climb and later crash land any given airplane in the sim, although instructions given to Luftwaffe pilots for Fw-190 (if I recall correctly) explicitly state that if you lose an engine (in terms of power), you should not try to crash land, but bail out (!), while there are many evidence showing that Bf-109 could actually belly land with little trouble. </div></BLOCKQUOTE>

have you heard about inertia?
As long you get some, you can climb or fly level (increasing the angle of attack progressively when the speed drop)
When your accumulated energy (inertia) is consumed, the only thing you can do is to glide, while maintening the minimum gliding speed if you don't want to stall.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">4. I feel that when flying at high angles of attack and low speed you should also lose altitude more significantly. To differently put it, when you dive to an airport at low speed and suddenly pull up nose above horizon, you shouldn't start climbing, but level up or continue to drop (depending on the aircraft type, speed and how much you pull your stick) and lose airspeed, which can result in realy nice landing, or crash if you miscalculated speed and height. Are this elements of the sim modelled right? Is flight at high angles of attack limited to speeds below 150kmph? </div></BLOCKQUOTE>

Only depends how much you pull the stick!!!

you need to pull gradually to compensate the loss of speed... but if you pull more, you will climb.
... ask the young pilot students when they experiment landing the first times... often they pull too much and start to climb instead of staying level for the infamous (and difficult to achieve in the begining) "landing 1m above the ground".

All these elements are modelled right in the sim.. at least for most of the planes.

(BTW... I'm a private pilot)

XyZspineZyX
02-06-2007, 11:11 AM
Wow. May I suggest the book "Mechanics of Flight" by A.C. Kermode.

Much of what you describe is utterly wrong. Its not how aerodynamics work. Most notably the loss of an engine bla bla...

A better explanation:

1. If you give it enough relative wind, anything will fly. Yes, when you bank the aircraft you are reducing the lift vector of the wings. However, you have a large mass with alot of surface area (the fuselage) still travelling through the air, at a decent speed. This is enough to counter some of the effect of gravity. So, you are sort of right, but only in a universe that has no fluids.

2. No. Rudder should be used to help the turn. To counter the effect of altitude loss, as explained above, use elevator.

3. When your engine cuts out, your airplane is still moving forward. As long as you can keep the airplane at a reasonable speed, it will glide for some time.Regarding the instructions to the Luftwaffe pilots, its most likely that the german aircraft, much like the Spitfire were a little risky to crash land. Seeing the Luftwaffe was a little short on pilots I can see why they told them to bail out to save their skins rather than risk hurting or killing themselves in a crash landing.

4. Inertia again. Look at how you describe it. If you are diving towards a runway, you are gaining some energy, or forward motion. When you pull on the stick you change the direction of flight and thus where that accumulated energy is going. So, you will climb if you pull too hard. Not only will you climb though, you will also all of a sudden lose your airspeed and plop down on the runway. <pre class="ip-ubbcode-code-pre"> </pre> <pre class="ip-ubbcode-code-pre"> </pre>

WWMaxGunz
02-06-2007, 02:56 PM
Rab, how long does it take a brick to fall just under 5 meters?

How about 1 full second to fall 16 feet?
Half-second falls only 4 feet?

If the pilot is busy with something then maybe he dies. If he is watching and on the stick then he pulls back and doesn't.

Way up in the sky you don't get close positional cues, try turning on wingtip smoke and keep your flight coordinated. As soon as you start to lose alt, your lift increases don't forget. And watch for the slip-roll coupling when you do bank up to 90 degrees without the nose wavering too much, mind the ball and make a track if you want to collect data. You can view your smoke trail when you play back and you can log instruments through UDPSpeed or like.

EDIT:
Don't forget that losing some speed does not mean losing all lift either. Kill your engine flying fast, fully trimmed and level and see how it falls hands-off. Watch the speed fall.

ivankuturkokoff
02-06-2007, 04:02 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">1. When you bank an aircraft, you are actually reducing vertical component of lift vector, which counters Earth's gravity. Having this in mind, when this component falls below gravity vector value, you end up with downward acceleration. Consequently, if you bank an aircraft 90 deegres (and don't use rudder in opposite direction) aircraft actually falls like a brick (losing altitude with downward acceleration of approx. 9,81 m per square second). The overall feel in game simply differs from this. </div></BLOCKQUOTE>

Err no.

As you bank your vertical component of lift reduces the amount varying directly as a function of bank angle. As a consequence a rate of descent will start. The pilot counters this by small increasing backstick inputs thus increasing Angle of attack and thefore lift. This increase in lift now compensates for the reduction in the vertical component caused by the bank.

In a 60 deg angle of bank level turn (2G) you will need to double the amount of lift to compensate for the loss in vertical component. In a 72degree angle of bank turn (3G) you will need to triple the amount of lift.

Of course this Angle Of Attack increase also increases drag so to hold your airspeed you need to increase power. This whole thing goes on as bank increases. eventually you arrive at a bank angle and Angle Of attack (G) combination whrere at max power at that bank angle you can just maintain level. This is your Thrust limited boundary or sustained turn limit.
For most FB fighters at sea level it occurrs at 3.5G or around 73.4 degrees angle of Bank.

In fact the essence of all Manoeuvering flight is the pilot controling the Lift vector both its magnitude and direction. The stick being the pilots Lift Vector control device. You roll to point your Lift vector, You pitch to both point and control the magnitude of your lift vector.

Hope that helps your understanding.

FritzGryphon
02-06-2007, 06:45 PM
And even at pure 90 degree bank, you can still maintain altitude via rudder and fuselage lifting. Can do this indefinitely on some high power aerobatic planes, and Ta-183 in-game http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

Tbag_13
02-06-2007, 06:54 PM
The guys at eastern skies did me a great favor when they told me about this link:

http://www.av8n.com/how/

Even if you don't have the time, take the time to read it. I was not new to aerodynamics at all when I read it first but to be honest - I think there are many pitfalls when you try to apply theory to real problems.

Rab03
02-07-2007, 08:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by EDCF_Rama:
The plane body and the tail generate some lift (for example a French Alphajet can fly level on side flying at 380 knts without lossing altitude).
Moreoever, for WWII planes, the wings angle makes it impossible to have both wing at 90?... so you have allways at least one wing giving a little lift.
</div></BLOCKQUOTE>

I sure don't believe that Alphajet can fly on side without rudder input or some other control surface, no matter what. You have symmetrical surfaces, right (upper/lower components ignored here)? As much lift you produce on the upper (ie. lateral, in this case), insignificantly different or the same quantity you produce on the lower side. The only way you can do it is if you apply rudder or you apply ruder, tilt nose of an aircraft upwards, thus changing the lateral (in this case vertical) AOA and the aerodynamic shape of sides of the fuselage produces extra lift on one side.
Similarly, wings are symmetrical. As much you gain from one, you loose with other (speaking of 90 degree case and straight path)!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by EDCF_Rama:
Your first reason is wrong, and you probably don't remember well what you did read in the flying school's manual.
When you turn, you need to give some foot inside the turn, to correct the induced yaw (the external wing going faster produce more lift and more drag, who tend to twist the plane nose toward the outside of the turn).
In order to keep level during turn, you use the elvator, not the rudder.
This is only if you try a prolonged turn near 90? that you need some ruder to fly level (as you would do if you fly on the side in a straight fly)... but then you should be very carefull with possible stall.
</div></BLOCKQUOTE>

Something known, something not. Notion taken. As I've said I had read it many years ago.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by EDCF_Rama:
have you heard about inertia?
As long you get some, you can climb or fly level (increasing the angle of attack progressively when the speed drop)
When your accumulated energy (inertia) is consumed, the only thing you can do is to glide, while maintening the minimum gliding speed if you don't want to stall.
</div></BLOCKQUOTE>

I have heard about inertia, and use it frequently. Consider this:
1. Closterman flew Spitfire, let's say, 500kmph several meters above surface of the water.
2. Plane's speed andf trim are set for level flight.
3. Engine loses power.
4. How much time would you think he would have had to react, and more importantly, what would have happened afterwards?

My opinion concerning this is very little. Entire problem is about aerodynamics in a sense of drag produced by a plane and speed loss in such situation (which, with other parameters maintaned the same, means instant start of losing altitude).

As for the glide, do you know who is the passanger plane glide record holder? Two French pilots who lost all their fuel and glided passanger plane from a height of approx. 10km to a military base in Azores travelling more than 100km in distance, landing a plane in a first attempt safely, with speed in excess of 300kmph. Their airspeed while gliding was much above 300kmph. Is modern passanger jet more aerodynamic than a WWII fighter or bomber?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by EDCF_Rama:
Only depends how much you pull the stick!!!

you need to pull gradually to compensate the loss of speed... but if you pull more, you will climb.
... ask the young pilot students when they experiment landing the first times... often they pull too much and start to climb instead of staying level for the infamous (and difficult to achieve in the begining) "landing 1m above the ground".

All these elements are modelled right in the sim.. at least for most of the planes.
(BTW... I'm a private pilot) </div></BLOCKQUOTE>

Great. As you could have guessed, I'm not. What do you fly with? What do those students fly with? I'm asking because I've seen a show in which they showed an amateur given the controls of an airplane (multi seat single-engine, resembles Piper Saratoga). He did everything nicely, but instructor reacted swiftly during landing because he saw that a guy didn't pull stick hard enough. Needless to say, plane pitched nose upwards remained level for a second and landed like a charm. If the instructor had pulled his stick all the way back, I doubt that that specific plane would have climbed more than a couple of meters and then plummet to runway.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Skunk241981:
Much of what you describe is utterly wrong. Its not how aerodynamics work. Most notably the loss of an engine bla bla...

A better explanation:
1. If you give it enough relative wind, anything will fly. Yes, when you bank the aircraft you are reducing the lift vector of the wings. However, you have a large mass with alot of surface area (the fuselage) still travelling through the air, at a decent speed. This is enough to counter some of the effect of gravity. So, you are sort of right, but only in a universe that has no fluids. </div></BLOCKQUOTE>

I always have fluids in my mind. I never said that you lose all of your lift when you lose engine power. I just questioned amount of speed loss and consequential loss of altitude in a specific situation.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Skunk241981:
2. No. Rudder should be used to help the turn. To counter the effect of altitude loss, as explained above, use elevator. </div></BLOCKQUOTE>

Notion taken.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Skunk241981:
4. Inertia again. Look at how you describe it. If you are diving towards a runway, you are gaining some energy, or forward motion. When you pull on the stick you change the direction of flight and thus where that accumulated energy is going. So, you will climb if you pull too hard. Not only will you climb though, you will also all of a sudden lose your airspeed and plop down on the runway. </div></BLOCKQUOTE>

OK, my description was wrong, but let me put it this way. I dive toward runway at a constant speed, which is something you can do using many methods available, right? And it also depends of the aircraft type, etc, etc. When you pull stick hard, especially with large and heavy aircraft, the plane continues to travel for a bit more in direction of previous path (amount of which depends on many, many factors), and that same path starts to change some little time after you applied the pull. As said earlier, amount of that climb, and distance travelled are in question.

How high would you end up in a typical, slow descent approach procedure with civilian airplane when you pull up hard, without increasing throttle, and before you stall or just drop on the runway? Would you have travelled to the opposite end of runway? I don't think so.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Rab, how long does it take a brick to fall just under 5 meters?

How about 1 full second to fall 16 feet?
Half-second falls only 4 feet?

If the pilot is busy with something then maybe he dies. If he is watching and on the stick then he pulls back and doesn't. </div></BLOCKQUOTE>

Nice, but you forget that the fastest reflex reaction of a man takes about 0.2 second. If you are expecting such a thing, maybe you will even react. Or would you be confused of what is happening and what to do for less than 0.8 second? My question also concerned what would have happened next in terms of how much high he would have climbed and how far he would get? Or, to put it differently is ingame ratio of drag/speed loss (and consequent loss of altitude) and inertia correct?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Way up in the sky you don't get close positional cues, try turning on wingtip smoke and keep your flight coordinated. As soon as you start to lose alt, your lift increases don't forget. And watch for the slip-roll coupling when you do bank up to 90 degrees without the nose wavering too much, mind the ball and make a track if you want to collect data. You can view your smoke trail when you play back and you can log instruments through UDPSpeed or like. </div></BLOCKQUOTE>

As I've said, I didn't want to go super scientific, because I don't have the time. And it's not way up, it's low level flight, very low level.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ivankuturkokoff:
Err no.

As you bank your vertical component of lift reduces the amount varying directly as a function of bank angle. As a consequence a rate of descent will start. The pilot counters this by small increasing backstick inputs thus increasing Angle of attack and thefore lift. This increase in lift now compensates for the reduction in the vertical component caused by the bank.

In a 60 deg angle of bank level turn (2G) you will need to double the amount of lift to compensate for the loss in vertical component. In a 72degree angle of bank turn (3G) you will need to triple the amount of lift.

Of course this Angle Of Attack increase also increases drag so to hold your airspeed you need to increase power. This whole thing goes on as bank increases. eventually you arrive at a bank angle and Angle Of attack (G) combination whrere at max power at that bank angle you can just maintain level. This is your Thrust limited boundary or sustained turn limit.
For most FB fighters at sea level it occurrs at 3.5G or around 73.4 degrees angle of Bank.

In fact the essence of all Manoeuvering flight is the pilot controling the Lift vector both its magnitude and direction. The stick being the pilots Lift Vector control device. You roll to point your Lift vector, You pitch to both point and control the magnitude of your lift vector.

Hope that helps your understanding. </div></BLOCKQUOTE>

It didn't help my understanding due to simple reason that I already know all this. As said in original post, I haven't got the time to explain everything, so I've put it in the simplest way possible.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FritzGryphon:
And even at pure 90 degree bank, you can still maintain altitude via rudder and fuselage lifting. Can do this indefinitely on some high power aerobatic planes, and Ta-183 in-game </div></BLOCKQUOTE>

Yes, as I've stated earlier, already know that, the question was about no rudder input situation.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tbag_13:
The guys at eastern skies did me a great favor when they told me about this link:

http://www.av8n.com/how/

Even if you don't have the time, take the time to read it. I was not new to aerodynamics at all when I read it first but to be honest - I think there are many pitfalls when you try to apply theory to real problems. </div></BLOCKQUOTE>

Great stuff, thx. I was not trying to apply only theory, but a practical hang of it also, and only on specific issues.

High AOA straight level flight? What speeds? Three-wheel landing? High AOA approach/loss of altitude?


Nobody said nothing about Fw-190 bug? Is there or it isn't there?

XyZspineZyX
02-07-2007, 09:43 AM
Regarding your point number 3...watch this video:
http://www.youtube.com/watch?v=TUVWHUR5OEI


Regarding this:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">As for the glide, do you know who is the passanger plane glide record holder? Two French pilots who lost all their fuel and glided passanger plane from a height of approx. 10km to a military base in Azores travelling more than 100km in distance, landing a plane in a first attempt safely, with speed in excess of 300kmph. Their airspeed while gliding was much above 300kmph. Is modern passanger jet more aerodynamic than a WWII fighter or bomber? </div></BLOCKQUOTE>

Actually they were Canadian pilots, to answer the "modern passenger jet more aerodynamic than a WWII fighter" the answer is yes. Advances in aerodynamics has produced some of the most efficient wings in the last 20 years.

Also regarding your point #4: If you increase the AOA of a wing at any speed you will increase lift. I suggest playing around with radio controlled airplanes to get a feel for it. Also, you may want to sit in the seat of an airplane with an experienced pilot and have him explain a few things to you.

Regarding the no rudder input situation, as stated, it depends on speed of relative wind.

Oleg is himself an aero engineer, so I'm pretty sure he got most of it right http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Rab03
02-07-2007, 11:12 AM
Wrong about pilots, sorry.

Nice movie, great flying. It shows that the airplane used has good gliding characteristics (gotta get me one of these). Very sleek lines.

But,there were, and maybe still are, two engine aircraft which cannot (this I say based on actual test data) not only climb, but remain level with only one engine. They simply lose altitude til they crash, usually killing the crew. Two engines out, fall like a brick.

Initial speed in the video was high. What was his starting altitude? There's nothing wrong with diving and looping with some aircraft, but that was not what I asked about.

Yes, I am aware that if you increase the AOA, you gain lift. And if you don't have power, you'll end up stalling or just droping down.
No rudder, 90 degrees bank, perfectly straight, and it doesn't at all depend on airspeed.

Is Oleg an aero engineer? As far as I remember, he worked in many military and aviation bureaus and factories, but don't recall that fact. And again, even if he is, he himself had said that it would take supercomputer to 100% realisticaly portray flight model of a real aircraft.

With nothing wrongful intended neither to Oleg or you, you must remember that many of flight model thingies were slowly introduced to FB over years (including more significant speed loss induced by power loss and tail sway to mention a couple). Oleg himself admitted that La5fn and Bf109g6as flight models were incorrect in original Il-2. Not that I'm saying that everything is wrong and bad, or that something is completely bad. I am only saying is that I feel it should be improved, based on my knowledge and perception.

Bug in Fw-190 damage model? Anything?

XyZspineZyX
02-07-2007, 01:44 PM
Oh there is nothing wrong with asking questions mate.

I just dont understand why you keep coming back with that "2 engines = falling like a brick" thing. Yes, without power you lose forward speed. We're still on your point #3 here...

Ok, you're at 500 km/h(I'm using the figures you mention) over the water, only a few meters. Lets say 10m above water. So your engine cuts out. Now what? You believe you should automatically crash in the water? Your deceleration should be instantaneous? Wouldnt instantaneous deceleration kill the pilot? I mean you have kinetic energy, at the point where your engine stops you are at 500 km/h. Depending on a lot of things, namely drag coefficient of the airplane, or air density that day for example, it would mean that you would lose speed at a certain, small rate. Which means with this built up energy you can climb and manoeuver quite a bit until that energy runs out. Every thing is just a matter of time.

Another example, you are in a twin engine plane, 200 km/h, 3000m up. Both engines quit. If you keep your plane on a steady course and try to keep the same altitude the airspeed diminishes very rapidly. At 3000m altitude you have quite alot of potential energy that can be converted into kinetic energy. Also, as long as there is enough wind going over your wings you will be able to stay aloft for quite some time.

Talk to glider pilots. Talk to pilots. They'll give you the simple explanation of how it works. Then talk to an aero engineer. He'll gladly complicate things for you.

Also:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">But,there were, and maybe still are, two engine aircraft which cannot (this I say based on actual test data) not only climb, but remain level with only one engine. They simply lose altitude til they crash, usually killing the crew. Two engines out, fall like a brick. </div></BLOCKQUOTE>

I think any aero engineer who were to design such an aircraft would be out of a job quite quickly.

Unfortunately, I dont recall anything I did in my high school physics classes or my fluids classes from college(atleast not enough to give a lengthy scientific answer)...

EDCF_Rama
02-07-2007, 06:24 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rab03:
I sure don't believe that Alphajet can fly on side without rudder input or some other control surface, no matter what. You have symmetrical surfaces, right (upper/lower components ignored here)? As much lift you produce on the upper (ie. lateral, in this case), insignificantly different or the same quantity you produce on the lower side. The only way you can do it is if you apply rudder or you apply ruder, tilt nose of an aircraft upwards, thus changing the lateral (in this case vertical) AOA and the aerodynamic shape of sides of the fuselage produces extra lift on one side. </div></BLOCKQUOTE>
Did I say you can fly level on a side without rudder input? No, I was just saying that with some planes, at certain speed, you can fly level with almost no lift generated by the wings (but of course, you need some rudder input).
It's exactly the same in the game. Try for example in game to fly on the side level above an airstrip (I tried with both FW190 and P39/P63 familly). With some training, with enough speed, with appropriate rudder input, you can fly level around half of a strip (around 1000m), until the drag generated by the assymetric flying will slow you down enough so you can't fly level anymore. Without rudder input, you will hit the ground very quickly.
All this seems to me correct (ingame)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Similarly, wings are symmetrical. As much you gain from one, you loose with other (speaking of 90 degree case and straight path)! </div></BLOCKQUOTE>
This is wrong. If one of the wing is perfectly vertical (and thus generate no lift), the other, because of dyedral angle wil not be vertical, and will generate (a little) lift if the speed is enought. If the inclination is exactly 90?, both wing will not be vertical, and will both generate a little lift. With a drawing you will see this easilly.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I have heard about inertia, and use it frequently. Consider this:
1. Closterman flew Spitfire, let's say, 500kmph several meters above surface of the water.
2. Plane's speed andf trim are set for level flight.
3. Engine loses power.
4. How much time would you think he would have had to react, and more importantly, what would have happened afterwards? </div></BLOCKQUOTE>
AT 500 Km/h, he has probably enough energy to climb up to a safe altitude to bailout, and has at least a few minutes to react (for climbing and bailing, or prepare to ditch... wich is a bit risky especially if the sea isn't totally waveless).
Something equivalent happen often in Reno air races. One warbird breake engine... and guided by the race director (who's flying over the race), he climb, and is guided to the best place to land (or to crashland)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">My opinion concerning this is very little. Entire problem is about aerodynamics in a sense of drag produced by a plane and speed loss in such situation (which, with other parameters maintaned the same, means instant start of losing altitude). </div></BLOCKQUOTE>
You just forget that there's nothing like "with other parameters maintaned the same", since the pilot is... piloting... and thus modifying the parameters.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">As for the glide, do you know who is the passanger plane glide record holder? Two French pilots who lost all their fuel and glided passanger plane from a height of approx. 10km to a military base in Azores travelling more than 100km in distance, landing a plane in a first attempt safely, with speed in excess of 300kmph. Their airspeed while gliding was much above 300kmph. Is modern passanger jet more aerodynamic than a WWII fighter or bomber? </div></BLOCKQUOTE>
This means that the jet has a gliding ratio of 10... and that his best gliding speed is "much above 300kmph".
You can expect for a warbird a best gliding speed (the speed to achieve the best gliding ratio)less than the jet best gliding speed (between 180 and 300 Km/h depending on plane).
Don't forget also that the best gliding speed is allways higher than the minimum gliding speed.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Great. As you could have guessed, I'm not. What do you fly with? What do those students fly with? I'm asking because I've seen a show in which they showed an amateur given the controls of an airplane (multi seat single-engine, resembles Piper Saratoga). He did everything nicely, but instructor reacted swiftly during landing because he saw that a guy didn't pull stick hard enough. Needless to say, plane pitched nose upwards remained level for a second and landed like a charm. If the instructor had pulled his stick all the way back, I doubt that that specific plane would have climbed more than a couple of meters and then plummet to runway. </div></BLOCKQUOTE>

I fly mostly DR400 (Robin).
What you describe is the instructor taking command just before touch down. At this moment the plane is near stalling speed, and yes, you need to pull a good amount to touch down nose up (and avoiding to break nose wheel).
For a DR400, touching speed is around 55kts, and final is around 65 kts. you can often see a student with a 10 kts margin (75kts), pulling a bit too much at the round out, throttle idle, and climbing at 10/15m over the runway instead of rouding out at 1m over... with still plenty of speed...
If the runway is long enough, if can go down for another round out and a landing... if not, he better apply full throttle and abort.

Rab03
02-07-2007, 08:33 PM
Skunk241981, 2 engine plane I mentioned realy existed and had been in production after the WWII. Designers were not fired,because in those days it was quite normal that planes perform differently. Given example was intended to illustrate that gliding characteristics of planes differ greatly, and stall flight, altitude drops, skidding, yawing, etc. also.

EDCF_Rama, DR400 is a beautiful little bird. In my country we mostly have Cessnas 152 and 172 and domestic older design quite similar to DR400 (except it's all metal, a tad heavier and with 180hp engine; from what I've seen believe performs a bit worse than DR400). As things are developing you'll make me getting a pilot license.
You puzzled me with wings producing lift a bit. Air doesn't care if you are flying level, upside down or at 90 degrees inclinitaion - the only thing that does matter is the gravity. If your explanation for 90 degrees inclinitaion is correct, that would mean that in level flight the plane would move sideways. Wing symmetry provides you with balanced, resultant lift directed upwards in relation to wings. When you fly at 90 degrees you have resultant lift generated by wings directed, in this case, to the side of upper wing surface, and not verticaly.

The point of my original questions was in quantities simulated in game.

Fw-190 damage model bug? Anyone?

EDCF_Rama
02-08-2007, 05:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rab03:
If your explanation for 90 degrees inclinitaion is correct, that would mean that in level flight the plane would move sideways. </div></BLOCKQUOTE>
Correct

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Wing symmetry provides you with balanced, resultant lift directed upwards in relation to wings. When you fly at 90 degrees you have resultant lift generated by wings directed, in this case, to the side of upper wing surface, and not verticaly. </div></BLOCKQUOTE>
Ok.. I used "lift" to qualify only the vertical component of the aérodynamic force créated by the airflow. I should have used "vertical component of lift" instead of lift.

Now, as someone else said, lift depend only on incidence angle and speed. lift provided by both wings is different in many case if wing speed (or speed of the center of pressure) is different).

a lot depend on Wing design.
A plane with no diedral angle (or with negative one), will have while entering turn the external (to the turn) wing flying faster, and thus producing more lift than the internal wing... until the 90? inclination (with no lift). This lift difference will have the tendancy to accelerate roll rate.
That's the reason of the diedral angle. When a plane enter a turn, the external wing has more inclination than the internal... and this compensate for the extra speed (more inclination means more lift.
At the extreme, a DR400 with a 2-angle wing, will loose a lot of lift on the external wing AND gain lift on the internal wing... thus creating a strong roll momentum to regain horizontal flight... that's the reason of her high lateral stability.

Philipscdrw
02-08-2007, 07:11 AM
The Robin aircraft are absolutely wonderful - very ingenious design of the wing, very high attention to low-drag fairings around things like, i.e., the nosewheel strut...

Regarding symmetrical objects getting lift, they CAN give lift when there's a positive angle of attack. So the Alphajet (which is symmetric sideways) can roll 90? and point its nose up above the horizon and make enough lift to fly.

WWMaxGunz
02-08-2007, 06:34 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rab03:
I am only saying is that I feel it should be improved, based on my knowledge and perception. </div></BLOCKQUOTE>

But you don't have time to get scientific.
You fail to include slip-roll coupling in what happens when you roll a plane.
You seem to have missed the day when Reynolds numbers were explained and how a jumbojet can
be extremely efficient even to the glide with empty tanks and stopped engines.
How much of what you don't know is part of your perception?
Yes a pilot can be holding the stick forward with trim set a bit back because when you are
holding the real stick, forward and back are relative to where it doesn't pull or push on
your hand anyway -- so you trim a tiny bit back and hold on to that. If the plane slows
down you will feel the stick pull harder and it won't be some huge amount right away. Your
hand should react by pulling harder before you know it and no, not enough to send you up
into a stall. Have you ever fought or done anything quick and also coordinated?

How long does the brick take to fall into the sea at the height you think they flew?
It's going to take the plane longer to fall that far even if the engine stutters and stops.
What happens after that if the engine fails is not about the FM at all is it?

You also write about banking 90 degrees which I don't think that was about flying just a
few _meters_ over water but seemed to be part of your list of not feel it is working right
and I can help items. So I did suggest attributing slip-roll coupling which is basic and
real into your ideas and viewing wingtip smoke from external to see your path rather than
go by feel... in a sim... and you don't want to get scientific?

Are you for real? And you want to take that up with Maddox Games?

Hey, there's a guy you should hook with here tout-suite, his forum name is Josf.

Rab03
02-12-2007, 06:35 PM
What's wrong with you, Max?

What's this got to do right now with roll-slip coupling?
Why do you think I don't know Jumbos are very aerodynamicaly effective?
I was listening to Reynolds number lecture (dozens of them), and use it on almost every day basis professionaly.
And no, you cannot react faster than .15-.2 seconds.

And if you don't trust proven fighter ace, it's your problem. I guess you've flown real Spitfire, Mustang or Bf-109? He said that they flew very, very low level (3-5 meters). He said he would have been dead. You doubt it, take the argument with him, not me.
BTW, can you determine the time/speed lost to carburetor engine stutter when going negative g? This issue will be very important when BoB is released, right?

What if I had asked this question before Maddox increased drag induced deceleration a year or so ago? What would have you said about it?
Call me a whiner? You think all the improvements made to this sim are needless? You believe this sim is 100% correct? Better find Oleg's posts and find that this sim is not 100% correct, but it's correct as it can be based on modern computer power and time/effort/money of developers.

I believe previous posts clarified aim of original post. And it certainly wasn't getting insulted by you.

And no, I don't have enough time to discuss these issues in detailed theory and practice.

BTW, nobody said nothing about FW-190 bug?
OK, track goes to Maddox.

VW-IceFire
02-12-2007, 08:10 PM
RE: Pierre Closterman...love his book and his writing style but it should not be used for arguments regarding aerodynamics. He likes to embellish a fair bit (most good writers do) and when he says "drops like a brick" you should take that to mean something like "eventually that plane will hit the water" (given the context).

WWMaxGunz
02-12-2007, 08:59 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rab03:
And no, you cannot react faster than .15-.2 seconds. </div></BLOCKQUOTE>

Let's try this again. Engine power loss, the plane is going to lose speed how quickly?
So it's not going to fall like a brick due to loss of power. But trim will change and the
plane may tip a bit nose down with the sudden drag right there. The plane at speed *could*
dive 10-20 feet in a second maybe less. Very possible. It did happen and more often during
close approach and landings have engine hiccups caused wrecks.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">And if you don't trust proven fighter ace, it's your problem. </div></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What if I had asked this question before Maddox increased drag induced deceleration a year or so ago? </div></BLOCKQUOTE>

You can prove that he specially did so? About a year ago was 4.0. A lot of things changed
and rudder becomes more real important. People who didn't handle the new modelling so well
were coming up with all kinds of BS which funny enough they still do.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What would have you said about it? </div></BLOCKQUOTE>

I'd say let's have the tracks and the method.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Call me a whiner? </div></BLOCKQUOTE>

Not yet. I'm not sure you are really what you say either.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> You think all the improvements made to this sim are needless? You believe this sim is 100% correct? Better find Oleg's posts and find that this sim is not 100% correct, but it's correct as it can be based on modern computer power and time/effort/money of developers. </div></BLOCKQUOTE>

Oh geez. 100%? To reality? Everything, FM/DM/view/control/etc.... no way even 50%.
And I have been computing since the 70's, it was my main work 80's-90's, yes I have some
idea of the limits of desktop PC's. No there is no way to get it all even in just FM with
no other machine usage than just that so hey a combat flight sim with so much else --yes--
I know there are shortcuts.
But things so simple as what you seem to suggest? Not when smaller things are also well
done.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I believe previous posts clarified aim of original post. And it certainly wasn't getting insulted by you.

And no, I don't have enough time to discuss these issues in detailed theory and practice.

BTW, nobody said nothing about FW-190 bug?
OK, track goes to Maddox. </div></BLOCKQUOTE>

Good the track gets sent.

This is about slip-roll coupling. You roll right and the nose wants to go left. That puts
you on your high bank turn with nose high unless you correct with rudder into the turn.
If you roll perfectly on axis 90 degrees then you will fall as an arrow. Go fire 200+mph
arrows and see how far they go before they mostly just fall. OTOH you can run the wingtip
smoke, do a perfect 90 deg bank while making a track and see for yourself from external
POV some kind of perspective view. Remember while falling to keep the nose level.

You have fun with Oleg. If you fly it wrong then he sees that and you get nowhere. If you
fly it wrong and don't know then what will you be left thinking? Oh, Oleg then must be wrong!