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XyZspineZyX
07-28-2003, 04:36 PM
Well... seeming you all have appeared to run out of new items to moan about, i thought i would point out a propeller under power when it clips or hits the ground WILL bend Forward not backwards as modelled in game....... Speaking from real experience of this over 25 years, it allows you to determine if the engine was under power when it hit, if it is at idle and not producing thrust it will bend rearwards but if under power the blades at the tips are straining to go forward and upon impact bend the blades in that direction. /i/smilies/16x16_smiley-wink.gif



Message Edited on 07/28/0303:39PM by Taylortony

XyZspineZyX
07-28-2003, 04:36 PM
Well... seeming you all have appeared to run out of new items to moan about, i thought i would point out a propeller under power when it clips or hits the ground WILL bend Forward not backwards as modelled in game....... Speaking from real experience of this over 25 years, it allows you to determine if the engine was under power when it hit, if it is at idle and not producing thrust it will bend rearwards but if under power the blades at the tips are straining to go forward and upon impact bend the blades in that direction. /i/smilies/16x16_smiley-wink.gif



Message Edited on 07/28/0303:39PM by Taylortony

XyZspineZyX
07-28-2003, 04:44 PM
isn´t it a little too demanding for a "game"?...I suppose that if you really want EVERY detail modelled, go for a 1.000.000$ pro sim, cauze for the price you paid for FB, it´s more than correct! /i/smilies/16x16_smiley-surprised.gif

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XyZspineZyX
07-28-2003, 04:44 PM
uhhh...no, sorry. That's not true. /i/smilies/16x16_smiley-wink.gif

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XyZspineZyX
07-28-2003, 05:03 PM
how's the fishing today tony?
or in the off chance that you are not joking (little winkey face) what alternate universe do you live in?

XyZspineZyX
07-28-2003, 05:11 PM
As a current Forensic Scientist, and somewhat familiar with a few airplane/liner crash scenes, the props under power will bend backwards. What is a great aid in determining power condition of the props are non-symetric bending of the total prop blades, and the appearance of "divots" in the ground when the plane just touches the earth.

For example, in some of the old WWII pictures of downed planes, a eaqually bent set of prop blades indicates a powered plane upon impact/landing. However, if one or two blades were bent, that would indicate a feathered on on powered prop when theat part of the plane contacted earth.

Bullet4N6

"You don't have to be good if you're lucky!!"

XyZspineZyX
07-28-2003, 05:11 PM
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XyZspineZyX
07-28-2003, 05:13 PM
Fishings fine, but the baits real /i/smilies/16x16_smiley-happy.gif but it is correct btw a prop under power will bend forward, if you think of it as it pulls through the air the blades are forming a cone forward with the bending motion on them, rather like a helicopter rotor does upwards,(same principal) when it srikes that bending motion in hand with the vertical movement makes the blades bend forwards

XyZspineZyX
07-28-2003, 05:14 PM
Uh huh huh hu.. he said universe.. uh huh huh hu..

XyZspineZyX
07-28-2003, 05:33 PM
Gambler and Commie,
Thanks!, Consider that this fish has "thrown the hook", and is wiser for it!

Bullet4N6

"You don't have to be good if you're lucky!!"

XyZspineZyX
07-28-2003, 05:34 PM
Bullet i'd er re examine your principals as they go forward initially then if power is pulled off they will naturally loop under themselves and fold backwards the tips will still be forward, if power is left on they will deform forward, want some proof? see

http://www.sumpthis.com/ntsbpetition/report/MIA00LA238.htm


Postcrash examination of the engine was performed by an FAA inspector and a representative from Lycoming Engines. The aircraft and engine fuel lines were found unobstructed. The propeller blades were bent forward, consistent with the engine running at the time of ground impact.

XyZspineZyX
07-28-2003, 05:40 PM
Don't have any experience of prop bending when plane impacts TREES. I can see that this may be truer in this case. BTW, I was commenting on the total bending of prop blades and not tips.

Bullet4N6

"You don't have to be good if you're lucky!!"

XyZspineZyX
07-28-2003, 05:44 PM
check out patsy cline aircraft wreck that is a classic with power on.

http://www.patsified.com/tragedy/airplane3.htm

XyZspineZyX
07-28-2003, 07:56 PM
Taylortony,
I have to admit I am rather perplexed for the following reason: there are many power-on crashes a year and yet neither Bullet2n6 (?) who appears to have experience, nor I (10 yrs ppl) nor the "patsy cline" page author (a piper owner) has seen this "forward bending" of the prop as result of power-on crash.

This is corroborated by my "common-sense" understanding that no matter that the prop under power might flex forward slightly (like rotor tips of helo "pick up") that force would surely be weaker than the force of the impact of the ground on the blades during the crash.

So I guess the question underlying my skepticism is this- if this "forward prop bending" occurs with power on crashes why is it a rare occurence?

perhaps it occurs occasionally because of the circumstances of the crash (ie: not crashing in a "straight line" but at an angle which catches the tip of the already forward bending blade and then accentuates it. (I'm thinking a nose high stall position, as an example)-

Anyhoo- always good to have one's assumptions challenged /i/smilies/16x16_smiley-happy.gif
What are your views as to rarity of occurence/ majority of crashes involving props bent backwards?

Cheers,
Cg

XyZspineZyX
07-28-2003, 07:58 PM
Why do you care for realism, if to you it is just a game?

This is your quote, and now it applies to you:

"Sigh... I feel sorry for you having such a big chip on your shoulder, Its a Game, thats all a Game, nothing more nothing less, you seem to have lost the plot over that with all this historical blurb."

Boy, that foot must seem awful big in your mouth.

XyZspineZyX
07-28-2003, 08:05 PM
Yea, since its a game, why have damage models at all. Just have the planes disappear when they get shot or crash. hedus, you worry way to much about stuff that does't matter, like skins you'll never see or at least never have to see if you don't want to. a damage model is something that is common to all planes and player. Not to mention that watching a plane take damage is one of the real highlights of the "game".

XyZspineZyX
07-28-2003, 08:07 PM
if you read the first post it was done as tongue in cheek post as the things for people to complain about seemed to be drying up, but the information posted was correct and people queried it so i answered it as far as possible, u intending to go through all my posts now your chip is growing into a hump lol ?, if you want i can copy the links to em and email them over to you, then you can enjoy yourself whiling away a few hours /i/smilies/16x16_smiley-happy.gif

XyZspineZyX
07-28-2003, 09:07 PM
Taylortony wrote:
- Well... seeming you all have appeared to run out of
- new items to moan about, i thought i would point out
- a propeller under power when it clips or hits the
- ground WILL bend Forward not backwards as modelled
- in game....... Speaking from real experience of this
- over 25 years, it allows you to determine if the
- engine was under power when it hit, if it is at idle
- and not producing thrust it will bend rearwards but
- if under power the blades at the tips are straining
- to go forward and upon impact bend the blades in
- that direction. /i/smilies/16x16_smiley-wink.gif
-
-
Get "Black Cross Red Star" Vol.II and look at the picture of crash landed soviet fighter on page 43. That must answer all of the questions... At least for me.


Regards,
sambar

XyZspineZyX
07-28-2003, 09:08 PM
This just doesnt make sense to me.... The plane is going forewards.. the prop impacts the ground, and the plan is STILL going foreward. Now, for a split second, that prop is IN the ground, with dirt infront of it. The plane is still going forewards, thus for that second that the prop is in the ground, the foreward motion of the plane causes it to bend backwards because of the resistance of the dirt on the prop.

http://www.geocities.com/bs87cr/Wurger2.txt

XyZspineZyX
07-28-2003, 09:20 PM
I dunno.... I have dozens of pics with planes that crashed and their props are bent back...just like in this sim...

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XyZspineZyX
07-28-2003, 09:29 PM
ok look at it this way the prop is in a cone facing forward so when weight is applied it bends forward initialy , now to bend back it has to in effect lift the plane to go overcentre before bending back, realise this aint always the case, but an indication of a prop being under power is the blades bend forward, they might then go back as it looses power but they do tend to go forward first

A bit like Q tips on a prop but i wont go down that route

XyZspineZyX
07-29-2003, 02:31 AM
Yeah, I know, I'm feeding the trolls. Sorry.
Props producing thrust at the time of impact will bend forward. Windmilling props will bend backward (all blades.) Feathered props will bend backward (bottom blades only.) The reason most crash photos have blades bent backward is because most controlled crashes (which leave an intact aicraft, as opposed to high speed, out of control impacts which leave a yard sale of tiny pieces) involve engine failure.
Think about it this way. Under power, the blades are at a positive angle of attack as they move through the air. The air is stationary relative to the ground (any difference is called wind, and is usually small compared to the aircraft's velocity through the air.) When the prop first encounters the ground, the prop is striking the ground at the same positive angle of attack as it had slicing through the air. Dirt is much more dense than air obviously, and when the prop hits it, it produces gobs more "lift" or thrust, even at partial power settings. This thrust is local to the blade tip, which quickly bends it forward. As the aircraft decends, more blade gets fed into the really dense air called dirt, and the blade curls forward.
For the cynical farmers in the crowd, you can experiment by setting your plows to an angle simulating the prop blade's angle of attack. Now raise the plow and get the tractor up to about 100 mph. Now drop the plow. The plow blade didn't bend in the airflow at 100 mph, but it sure will when it hits the dirt.
As far as replicating this in the game, get a life. Aren't the metal/wood prop variations correctly modeled for each aircraft type, enough for you?

Blotto

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"Look, do you want the jets, or would you rather I slap the props back on?" - W. Messerschmitt

XyZspineZyX
07-29-2003, 02:52 AM
Correct...

Props under power do bend forward.
It seems there are many fish here jumping into the boat - even when he offered you no bait!

XyZspineZyX
07-29-2003, 03:34 AM
It's not exactly as simple as you state, both cases of props bending forward and rearwards with power applied have existed and I'm not saying it's random, but it has some dependence on phase of flight during the accident. A crash during a full rated power, high alpha and low airspeed situation which occurs on takeoff probably will cause prop blades to be bent forward as the aircraft is travelling much slower relative to the theoretical pitch of the propeller. This is the most common phase of flight for accidents.

A crash at cruising speed is a bit harder to say exactly, but you are likely to see appearances of rearward bending in this situation and it's more probable under partial power.


In high speed crashes near or over Vne (Never Exceed speed, airframe damage imminent), rearward bending is more likely or almost expected, the prop is sometimes not even connected anymore as such crashes are so violent. In such cases, an inspector can tell if power was applied by looking at how far the blades have been deflected laterally.


Some here are implying some aerodynamic effect or prop coning, but these are incoherent suggestions. The factor here is how the pitch of the propeller causes it to literally deflect forwards as if trying to propel itself, given that there is enough power applied and that the aircraft is flying slower than the prop's theoretical pitch rating.

Message Edited on 07/28/0310:59PM by Flightvector

XyZspineZyX
07-29-2003, 03:55 AM
Interesting......and to add to that...I was flying in a P-40 and I looked out at it and lo and behold as I applied thrust...the blades looked like they were moving forward!!!! Very interesting.....

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XyZspineZyX
07-29-2003, 05:01 AM
- For the cynical farmers in the crowd, you can
- experiment by setting your plows to an angle
- simulating the prop blade's angle of attack. Now
- raise the plow and get the tractor up to about 100
- mph. Now drop the plow. The plow blade didn't bend
- in the airflow at 100 mph, but it sure will when it
- hits the dirt.



Excellent advice for a real world demonstration Blottdog, but lemme tell ya what, I'll NEVER try that again in my life I tell ya what, that tractor was like to shake apart by the time I got it to 100mph, and the plow, K-Riste I was hammerin and wrappin chicken wire around that thing fer 2 days gettin it back inta shape. K-Riste.

XyZspineZyX
07-29-2003, 01:17 PM
I have personal experience of breaking a/c propellors. It was a wooden one and it shattered, so I guess it does not add much to this argument!

I'd never join a club that would have ME as a member!!.

Tully__
07-29-2003, 01:25 PM
Cold_Gambler wrote:
- Taylortony,
-
- So I guess the question underlying my skepticism is
- this- if this "forward prop bending" occurs with
- power on crashes why is it a rare occurence?

I suspect it depends on the consistency of the surface. Water and soft (marshy) surfaces are (at a guess) more likely to end in this result than hard, resistant surfaces.

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XyZspineZyX
07-29-2003, 01:56 PM
Darned if I understood.

This prop, obviously bent forward, was damaged with the engine on idle after the pilot *REALLY* wanted to land instead of abort and go around. There wasn't anywhere near enough runway to stop. I think the speed of the aircraft was still quite high at the prop strike, but I was standing some 400m away at the time, so I can't be absolutely sure. It hit a grassy dirt pile, not much bigger than an anthill.

http://infoworx.se/torget\rfk\bilder.nsf/vyImages/1199-3/$File/Visning.jpg?OpenElement
_
/Bjorn.

XyZspineZyX
07-29-2003, 05:32 PM
Wow- what I thought was kind of an inane topic turned out to be pretty interesting!! (and funny- lol at lignite! hope you're tractor's ok bud /i/smilies/16x16_smiley-wink.gif


In the end Blottog and Flight vector's comments made most sense to me:

"Some here are implying some aerodynamic effect or prop coning, but these are incoherent suggestions. The factor here is how the pitch of the propeller causes it to literally deflect forwards as if trying to propel itself, given that there is enough power applied and that the aircraft is flying slower than the prop's theoretical pitch rating."

combined with swingman's picture: in that pic you can clearly see how the fixed Aoattack of the prop, combined with power, deflected and bent the prop in an exagerration of the blade's Angle of Attack, rather than biting into the soil and being bent backwards by the aircrafts forward inertia...

pretty cool! another mystery of the universe solved! /i/smilies/16x16_smiley-very-happy.gif

Cold_gambler



Message Edited on 07/29/0304:54PM by Cold_Gambler

XyZspineZyX
07-29-2003, 07:26 PM
I knew this little film of mine on my Site would come in handy some day...

Perhaps it Is hard to say if the engine is under power or windmilling, but I sure do think this is a great Pat on the Back for the realism of IL2:FB


This is a link to the page/movie on my Site; IF you desire to see more of the Site, I strongly recommend that you do NOT "back into" the Site from this page, but rather that you follow the Link in my Sig Block below to Enter the Site through the "Front Door", otherwise you'll get lost:

http://people.ee.ethz.ch/~chapman/flightsims/oberstguncam/Frameset/comparisonmoviesone.htm



This is a link to stream just the little movie:

http://people.ee.ethz.ch/~chapman/flightsims/oberstguncam/Frameset/../Movies/P47bellyGlenn.WMV

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XyZspineZyX
07-29-2003, 10:01 PM
Cold_Gambler wrote:

Taylortony,

So I guess the question underlying my skepticism is
this- if this "forward prop bending" occurs with
power on crashes why is it a rare occurence?

Dont forget unless the pilot is a total idiot upon the intial sound of metal against mother earth the instinct is to close the throttle, bit like you changing down to first gear in a car at 100 mph, the redlining and the sound of the engine reving its nuts off soon instills the desire to rapidly change up or put the clutch in.

Similar in a plane, I had a real bad carb fire on the ground once and had flames licking up around the windscreen and i have to admit the temptation to run away rather than sit there cranking the starter to death was overpowering, suppose the thought of all the repairs i would have to do made me stick with it along with giving the other 2 people in the Aircraft a chance to get clear.

XyZspineZyX
07-29-2003, 10:20 PM
- Dont forget unless the pilot is a total idiot upon
- the intial sound of metal against mother earth the
- instinct is to close the throttle, bit like you
- changing down to first gear in a car at 100 mph, the
- redlining and the sound of the engine reving its
- nuts off soon instills the desire to rapidly change
- up or put the clutch in.

Yeah, Blottog also made the point that many crashes occur because of engine failure. Which leaves situations like controlled flight into ground, or sudden pilot incapacitation (heart attack, for example)- which are statistically rare enough to explain the rarity of these occurences.

- Similar in a plane, I had a real bad carb fire on
- the ground once and had flames licking up around the
- windscreen and i have to admit the temptation to run
- away rather than sit there cranking the starter to
- death was overpowering, suppose the thought of all
- the repairs i would have to do made me stick with it
- along with giving the other 2 people in the Aircraft
- a chance to get clear.

Sounds prettty hairy. Worst I ever had was an alternator failure fortunately I was doing touch and go's and noticed the ammeter quickly enough to request a full stop and land before the battery was drained. Not very exciting, perhaps, but it was exciting enough for me- I spent the next few flights giving that gauge a glance every minute or so lol.

Wiley,

I love the way you follow up the real footage with FB footage- it almost looks like a replay!!
Kudos to Oleg... I'm going to try to prop strike under power tonight and see if Oleg hasn't, in fact, modelled this!! ;D