Blunt Trailing Edges

[......... :-\)\)]

Hi All,

Many modern aerobatic aircraft have blunt trailing edges on the wing and
ailerons. Can someone tell me:

1. Why it this done - what are the benefits and side effects. There is a lot
of contradictory information on the web and I simply cannot get to the
bottom of it.

2. What is theory behind it (a technical explanation please - I am an aero
engineer and understand aerodynamics and stability and control etc).

3. Who was the first to do it.

I have looked in all kinds of text books on stability and control and none
of them address the issue. This type of trailing edge appears to be unique
to aerobatic aircraft.

Thanks,

Steve

[djpacro]

Go to the NACA report server and search for airfoil trailing edge.
http://naca.larc.nasa.gov/
Different airfoil sections but you should see the origins of claims for
improved lift curve slope, control effectiveness and changes to hinge
moments.

[[email protected]]

here is what I have read somewhere.

Blunted trailing edges on the wings such as are found on the Extra
series of aircraft where I believe this practice was first undertaken
cause a delay in the stall. Something to do with the turblence and the
associated vacuum causing a delay in separation. To the best of my
knowledge the idea was explored in Germany during the 40's(?). Having
looked at these aircraft up close these blunted trailing edges are 1/4
thick at most and I gather their effect is significant or I suspect Mr.
Extra would have done something else.

Cheers



.......... :-)) wrote:
> Hi All,
>
> Many modern aerobatic aircraft have blunt trailing edges on the wing and
> ailerons. Can someone tell me:
>
> 1. Why it this done - what are the benefits and side effects. There is a lot
> of contradictory information on the web and I simply cannot get to the
> bottom of it.
>
> 2. What is theory behind it (a technical explanation please - I am an aero
> engineer and understand aerodynamics and stability and control etc).
>
> 3. Who was the first to do it.
>
> I have looked in all kinds of text books on stability and control and none
> of them address the issue. This type of trailing edge appears to be unique
> to aerobatic aircraft.
>
> Thanks,
>
> Steve
>
>
>

[Markus Feyerabend]

Thanks for the update!

Last summer I had the chance to have a look at the SP-55 up close and the
trailing edges of all flying surfaces where extremely thick. From 1/4 inch
on the wingtip (or elevator/rudder) to more than 1 inch on the wing root. I
was wondering what this is for and the russian engieneer I asked couldn´t
answer...

Cheers

> schrieb im Newsbeitrag
.. .
> here is what I have read somewhere.
>
> Blunted trailing edges on the wings such as are found on the Extra series
> of aircraft where I believe this practice was first undertaken cause a
> delay in the stall. Something to do with the turblence and the associated
> vacuum causing a delay in separation. To the best of my knowledge the idea
> was explored in Germany during the 40's(?). Having looked at these
> aircraft up close these blunted trailing edges are 1/4 thick at most and I
> gather their effect is significant or I suspect Mr. Extra would have done
> something else.
>
> Cheers

[Scott Rodriguez]

I believe this helps with rapid centering of the control, minimizes control
surface overshoot, and allows the pilot to "feel" the center better.

> wrote in message
.. .
> here is what I have read somewhere.
>
> Blunted trailing edges on the wings such as are found on the Extra
> series of aircraft where I believe this practice was first undertaken
> cause a delay in the stall. Something to do with the turblence and the
> associated vacuum causing a delay in separation. To the best of my
> knowledge the idea was explored in Germany during the 40's(?). Having
> looked at these aircraft up close these blunted trailing edges are 1/4
> thick at most and I gather their effect is significant or I suspect Mr.
> Extra would have done something else.
>
> Cheers
>
>
>
> ......... :-)) wrote:
> > Hi All,
> >
> > Many modern aerobatic aircraft have blunt trailing edges on the wing and
> > ailerons. Can someone tell me:
> >
> > 1. Why it this done - what are the benefits and side effects. There is a
lot
> > of contradictory information on the web and I simply cannot get to the
> > bottom of it.
> >
> > 2. What is theory behind it (a technical explanation please - I am an
aero
> > engineer and understand aerodynamics and stability and control etc).
> >
> > 3. Who was the first to do it.
> >
> > I have looked in all kinds of text books on stability and control and
none
> > of them address the issue. This type of trailing edge appears to be
unique
> > to aerobatic aircraft.
> >
> > Thanks,
> >
> > Steve
> >
> >
> >