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View Full Version : FM-Is it right that a LA5FN is "unable" to stall??



Abbuzze
07-24-2006, 07:06 AM
A thread in the GF let me ask this.

I discovered this some time ago. Turning as hard as possible, elevator trim max. up Stick pulled to the bitter end no stall.

Did the LA5FN had not enough elevator movement to stall this plane at in a 90-80 degree bank at 2.3g and a 170m turning radius at 225km/h TAS?


But charts say more than 1000 words so here the result of the log.

Any source that this behavior is real?


http://img228.imageshack.us/img228/4488/la5fn405turnbj2.th.jpg (http://img228.imageshack.us/my.php?image=la5fn405turnbj2.jpg)

Abbuzze
07-24-2006, 07:06 AM
A thread in the GF let me ask this.

I discovered this some time ago. Turning as hard as possible, elevator trim max. up Stick pulled to the bitter end no stall.

Did the LA5FN had not enough elevator movement to stall this plane at in a 90-80 degree bank at 2.3g and a 170m turning radius at 225km/h TAS?


But charts say more than 1000 words so here the result of the log.

Any source that this behavior is real?


http://img228.imageshack.us/img228/4488/la5fn405turnbj2.th.jpg (http://img228.imageshack.us/my.php?image=la5fn405turnbj2.jpg)

IIJG69_Kartofe
07-24-2006, 07:48 AM
http://forums.ubi.com/images/smilies/blink.gif

I've already seen La5FM stall...

But it depend of what you call stall.

Stall has different definitions, the most correct is IMHO "when the plane simply stop flying and fall like a brick", the other is "when a wing of the plane drop", but this can happen on some plane @ high speed if you apply too rude stick movement.

BBB_Hyperion
07-24-2006, 07:54 AM
I doubt but got track ?

Abbuzze
07-24-2006, 08:20 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BBB_Hyperion:
I doubt but got track ? </div></BLOCKQUOTE>

I can reproduce them everytime. Just made one with 8 full turns. At 230km/h I reached my sticklimit - at the 6th turn I started to talk to my girlfriend next to me so I crashed at the 9th turn. Sorry it´s possible to do this longer, but it is boring http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Of course you can stall a FN, but not under the circumstances I described. At the chart you can see a small stall at 3g (peak downwards), but once reached low speed no chance to to this again, you can even climb when using the rudder.

Track:
http://mitglied.lycos.de/p1234/zip/LA5.zip

BBB_Hyperion
07-24-2006, 08:28 AM
Sie versuchen, auf eine Datei zuzugreifen, die auf einer privaten Mitgliederseite auf Tripod kostenlos gehostet wird:
http://mitglied.lycos.de/p1234/zip/LA5.zip

Um auf diese Datei zuzugreifen, müssen Sie in den Account über die Startseite der Mitgliderseite einsteigen:
http://mitglied.lycos.de/p1234
(Weiterleitung in 5 Sekunden)

Try rapidshare.de .)

Abbuzze
07-24-2006, 08:34 AM
should work with rightclick "save as" but here is the rapidsharelink:

http://rapidshare.de/files/26841450/LA5.zip.html

BBB_Hyperion
07-24-2006, 09:29 AM
http://rapidshare.de/files/26845832/la5fn.xls.pdf.html

Short Analysis of the Track.

First Chart rollpositiondistribution in complete track file.

Second one shows rollposition vs actual speed in ias.
You can see that the most part of the speed margin the plane is about 75 degrees banked.

3rd shows climbratedistribution . Plane goes up and down like a yoyo .

What we see here is that brute force of the engine can keep the plane from falling it shifts up and down on the y axis to counter too low liftforce.

We can see that the plane is at absolute limit of the stallspeed at around 200 IAS.

How about reducing engine power at this point shouldnt it stall then ?

Abbuzze
07-24-2006, 09:41 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BBB_Hyperion:


We can see that the plane is at absolute limit of the stallspeed at around 200 IAS.

How about reducing engine power at this point shouldnt it stall then ? </div></BLOCKQUOTE>

Yes I think so, no doubt about this, but If the FM of the plane is absolutly correct till 100% enginepower and wrong above, the complete FM is worthless because the way we are used to fly in this game. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

So the simple question is, was the real engine strong enough to create this effect?

EDIT: The yoyo effect is not real a necessarty but created by my unabilty/uninterest to be a perfect testpilot, so nevertheless If I´m able to fly this way, then all others are also able to do this.

BBB_Hyperion
07-24-2006, 11:00 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Abbuzze:

So the simple question is, was the real engine strong enough to create this effect?

EDIT: The yoyo effect is not real a necessarty but created by my unabilty/uninterest to be a perfect testpilot, so nevertheless If I´m able to fly this way, then all others are also able to do this. </div></BLOCKQUOTE>


I doubt that i think they missed some weight on the la5fn http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

The yoyo effect is actualy important like riding the stall so stall effect gets never in effect cause plane glides down by the lack of lift which prevents stall.

Aileron deflection (degrees) up18 down18
Tail plane deflection (degrees) up30 down16.5
Rudder deflection (degrees left and right)25 25


Slat deflection (degrees)@ 210km/h (IAS) 11.75 11.75

Sustained turn time (360 degrees low altitude) 19 sec's

There is some contradiction with first hand Czech pilot accounts of flying the La5FN during May 1944. These quite clearly state that augmented power derived from revving over 2400rpm to 2500 rpm was only available from take off and only sustainable for a period of upto 2 minutes immediately after take off.

Later these same accounts referred to the need to watch cylinder head temperatures to safe guard form over heating. Further speculation would offer that the improved cowl design and rerouting of the exhaust pipes on the La7 over the La5FN allowed for better engine cooling.

We know that the La5FN was under continuous development and would have benefited where possible from advances made in the La7. I would speculate therefore that earlier1943 and early 1944 La5FN models did not have a useful level of augmented power beyond take off (and any extreme measures undertaken by the pilot) but that this capacity would have been improved upon in later models upto November 1944 when the La5FN ceased production.

Augmented power duration per flight

2 mins

Sea level 2500 rpm (Augmented) 1850hp
Sea level 2400 rpm (Normal max.) 1650hp

Propellor VISh -105V

Weight (with pilot) fully laden 3360kg
Wing area 17.59m

sudoku1941
07-24-2006, 11:43 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Abbuzze:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BBB_Hyperion:


We can see that the plane is at absolute limit of the stallspeed at around 200 IAS.

How about reducing engine power at this point shouldnt it stall then ? </div></BLOCKQUOTE>

Yes I think so, no doubt about this, but If the FM of the plane is absolutly correct till 100% enginepower and wrong above, the complete FM is worthless because the way we are used to fly in this game. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

So the simple question is, was the real engine strong enough to create this effect?

EDIT: The yoyo effect is not real a necessarty but created by my unabilty/uninterest to be a perfect testpilot, so nevertheless If I´m able to fly this way, then all others are also able to do this. </div></BLOCKQUOTE>

No engine of this era is powerful enough to prevent a stall indefinitely if you're doing energy-burning maneuvers like this.

Look to the usual energy bleed problems of the basic flight model, or perhaps some data errors for the culprit.

SkyChimp
07-24-2006, 05:42 PM
I once took a head-shot while flying the La5FN. The friggin plane looped and looped never crashing. I kept on and on until I got tired of watching it and stopped the game. It's a "special" plane, no doubt.