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MB_Avro_UK
06-05-2008, 11:48 AM
Hi all,

Any aerodynamics experts here? http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

In il2, if for instance an aircraft looses it's tail section, the aircraft tumbles 'head over heels', i.e. rotating around the wing axis.

IMHO, the aircraft with this type of damage would fall vertically due to the centre of gravity moving substantially towards the nose.

The aircraft would then either reach terminal velocity or perhaps break up before hitting the ground.

Also, would an aircraft that has lost one wing continue to rotate around the fuselage axis until it hit the ground?

I realise that work on il2 has finished apart from the the next patch but this aspect relates to the future SoW release.

I have posted a similar thread on the 1C forum but I'm interested to hear your views.


Best Regards,
MB_Avro.

Jambock_Dolfo
06-05-2008, 11:58 AM
I don't know if it varies from plane to plane...

But there is a real example on this video:
http://www.metacafe.com/watch/237800/aero_gp_malta_2006...r_vargas_last_stunt/ (http://www.metacafe.com/watch/237800/aero_gp_malta_2006_gabor_vargas_last_stunt/)

*note: someone actually died on this accident. so if you do not wish to see it, do not click the link.


-dolfo

MB_Avro_UK
06-05-2008, 12:09 PM
Originally posted by Jambock_Dolfo:
I don't know if it varies from plane to plane...

But there is a real example on this video:
http://www.metacafe.com/watch/237800/aero_gp_malta_2006...r_vargas_last_stunt/ (http://www.metacafe.com/watch/237800/aero_gp_malta_2006_gabor_vargas_last_stunt/)


*note: someone actually died on this accident. so if you do not wish to see it, do not click the link.


-dolfo


Thanks for posting. And yes,a tragic loss of life.

The aircraft that lost it's tail appeared to dive vertically?

Best Regards,
MB_Avro.

Jambock_Dolfo
06-05-2008, 12:24 PM
Originally posted by MB_Avro_UK:


The aircraft that lost it's tail appeared to dive vertically?

MB_Avro.

Yes, after tumbling and stabilizing I would say vertical nose-down on this one. There are other videos of this accident around if you care to look for them.

-dolfo

Airmail109
06-05-2008, 12:27 PM
Jeeze thats a seriously low and quick bail out.

That second pilot was so unbelievably lucky

SaQSoN
06-05-2008, 12:58 PM
Do not forget, that aircraft is moving in the air and besides gravity, there are also certain aerodynamical forces being applied to it.

The aerodynamical focus (summ of all aerodynamical forces, applied to the wing) of the plane's wing is situated infront of the plane's CG. Which, obviously produces nose-lifting momentum.

To compensate it, they, occasionally, invented the horisontal stabilizer. :-) So, when it is lost - the aircraft will turn over the tail...

Jambock_Dolfo
06-05-2008, 01:09 PM
Originally posted by SaQSoN:
Do not forget, that aircraft is moving in the air and besides gravity, there are also certain aerodynamical forces being applied to it.

The aerodynamical focus (summ of all aerodynamical forces, applied to the wing) of the plane's wing is situated infront of the plane's CG. Which, obviously produces nose-lifting momentum.

To compensate it, they, occasionally, invented the horisontal stabilizer. :-) So, when it is lost - the aircraft will turn over the tail...

Actually on conventional stable airplanes the horizontal stabilizer forces the tail down, and the nose up... without it's force the natural tendency of the nose would be to go down. That is why when you stall a stable conventional-tail airplane the nose drops allowing the speed to increase, and flight to be recovered.

Standard conventional tail stable airplane with horizontal stabilizer missing = nose down.

-dolfo

SaQSoN
06-05-2008, 02:32 PM
When you stall a stable conventional-tail airplane, the wing STOPS TO PRODUCE LIFT. That is why aircraft drops nose down.

Both wing AND horisontal stab produce LIFT, i.e., aerodinamical force, pointed UPWARDS.

There is a certain kind of aerodynamical scheme, called "Utka" (Duck) in Russian (don't know the correct term for it in English), where horisontal stabilizer produces force, pointed down. But, in this case the H-stab is positioned infront of the wing.
This scheme proved to be unsuccessful, since in certain flight situations the H-stab would start producing lift, which led to complete loss of stbility.

Jambock_Dolfo
06-05-2008, 03:30 PM
Originally posted by SaQSoN:
When you stall a stable conventional-tail airplane, the wing STOPS TO PRODUCE LIFT. That is why aircraft drops nose down.

Both wing AND horisontal stab produce LIFT, i.e., aerodinamical force, pointed UPWARDS.

There is a certain kind of aerodynamical scheme, called "Utka" (Duck) in Russian (don't know the correct term for it in English), where horisontal stabilizer produces force, pointed down. But, in this case the H-stab is positioned infront of the wing.
This scheme proved to be unsuccessful, since in certain flight situations the H-stab would start producing lift, which led to complete loss of stbility.


Mixing things up my friend...
The "duck" thing, or canard, french for duck, is a different matter.
A stable canard design has the forward plane producing UPforce. And is designed in a way it will stall before the main wing. So if you stall the canard the nose drops and the plane resumes normal flight. You can find this behaviour on canard-cozy, long-ez planes and the likes.
An UNstable canard design has the canard producing downforce, as you described. This makes for a very unstable (if you stall the canard the departure is irrecoverable) design, but very maneuverable. Like Su3x, eurofighter typhoon, saab grypen.

For a STABLE conventional tail plane the horizontal stabilizer produces downforce. The wing momentum is nose-down, and the down force from the tail is required to stabilize the plane. The UNstable conventional tail has the stabilizer producing a. upforce. F-16 and similar planes.
Thing is, unstable planes have to be flown by computers, the fly-by-wire thingy. Because they depart controlled flight very quickly.


I don't like to speak out of memory. I went through basic flight theory in the flight school 16 years ago, and in the UNI 12 years ago. So memory fades sometime. But the above is correct. If I can find any good book around here I will try and post something more concrete than just recollections.

-dolfo