Today's Message Index:
----------------------
1. 02:28 AM - Re: Landing the KIS TR-1 (BlueSkyFlier)
2. 08:58 AM - Prince propellers and rain (Scott Stearns)
3. 03:49 PM - Re: Re: Landing the KIS TR-1 (Graham Brighton)
4. 04:49 PM - Re: Landing the KIS TR-1 (BlueSkyFlier)
5. 07:49 PM - Re: Re: Landing the KIS TR-1 (Mark Kettering)
6. 10:02 PM - Re: Re: Landing the KIS TR-1 (Larry David)
Message 1
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Subject: | Re: Landing the KIS TR-1 |
Of particular interest in the diagram which illustrates changes in lift coefficient
in ground effect [attached to previous message above] is the tendency for
lift to drop away when less than 20% of wingspan away from the ground if the
CL > 2.
With full flaps the TR-1 wing can apparently achieve CL > 2 if the angle of attack
is steep enough. In fact, when holding off with full flaps at high angle of
attack in close proximity to the ground it is likely that this unexpected drop-off
effect could be encountered - not to mention the contribution of adverse
tail plane effects.
It therefore seems important to keep the angle of attack fairly conservative. This
can be done by flying the main gear into touch with a fairly low angle of
attack and comfortable speed (probably > 60 kts) . Once the gear is down the nose
can be pulled up gently to generate maximum drag (the TR-1 will fortunately
not easily lift off again without power).
(The equation from which the lift coefficient chart attached above was created
is attached below for interest. The TR-1 aspect ratio being less than 7 will tend
to exacerbate the unwanted effects.)
-- ** --
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=336265#336265
Attachments:
http://forums.matronics.com//files/ground_effect_lift_equation_211.jpg
Message 2
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Subject: | Prince propellers and rain |
Hello all,
-
I wrote to the Prince propeller guy about the effects of rain on his propel
lers and here is his response.- My propeller is about 2 years old.
-
Scott
Mr. Stearns,
-
As we have been taught in pilot training it is best, even with a metal prop
eller, to reduce rpm to slow erosion of the propeller. The propeller will h
ave paint wear in moderate or greater rain as with any propeller be it meta
l or with leading edge protection. We offer a leading edge tape kit to redu
ce this condition. Your propeller was our older epoxy based material and do
es work well but continued use at high rpm in moderate or greater rain will
shoe wear. Our new material, urethane, is much more durable.
-
www.princeaircraft.com
Lonnie Prince
CEO/President
Prince Aircraft Company
PO Box 2669
6774 Providence Street
Whitehouse, Ohio 43571
Tel. (419)877-5557
Fax (419)877-5564
e-mail lonnie@princeaircraft.com
Message 3
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Subject: | Re: Landing the KIS TR-1 |
Alfred ,
Thx for sharing ur amazing and comprehensive study of the
Laminar Flow lift characteristics that CHANGE at landing as applied to our
TR-1 ..
My head like others is still er..'spinning' ...but ..ur
preposition as i understand it ....which is backed up ur substantial
research is ....that its the lift changes on our Laminar Wing at touch down
that causes the nose to drop and be hard/impossible to hold up after mains
touch down ... ( the wing lift/moment changes causes the Tail to loose
authority to counter the drop) ..
However with careful Speed and Flap selection the 'Nose
Drop' effect can be minimized ..
Great work ...Do i have this rite or .... !?
Graham
TR1 #80
.
----- Original Message -----
From: "BlueSkyFlier" <bleuskyfly@teledynamix.com>
Sent: Wednesday, April 06, 2011 7:27 PM
Subject: KIS-List: Re: Landing the KIS TR-1
> <bleuskyfly@teledynamix.com>
>
> Of particular interest in the diagram which illustrates changes in lift
> coefficient in ground effect [attached to previous message above] is the
> tendency for lift to drop away when less than 20% of wingspan away from
> the ground if the CL > 2.
>
> With full flaps the TR-1 wing can apparently achieve CL > 2 if the angle
> of attack is steep enough. In fact, when holding off with full flaps at
> high angle of attack in close proximity to the ground it is likely that
> this unexpected drop-off effect could be encountered - not to mention the
> contribution of adverse tail plane effects.
>
> It therefore seems important to keep the angle of attack fairly
> conservative. This can be done by flying the main gear into touch with a
> fairly low angle of attack and comfortable speed (probably > 60 kts) .
> Once the gear is down the nose can be pulled up gently to generate maximum
> drag (the TR-1 will fortunately not easily lift off again without power).
>
> (The equation from which the lift coefficient chart attached above was
> created is attached below for interest. The TR-1 aspect ratio being less
> than 7 will tend to exacerbate the unwanted effects.)
> -- ** --
>
> --------
> _________________________________________
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=336265#336265
>
>
> Attachments:
>
> http://forums.matronics.com//files/ground_effect_lift_equation_211.jpg
>
>
>
Message 4
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Subject: | Re: Landing the KIS TR-1 |
Hi Graham,
Unfortunately it is never just one thing. Far too much going on at the same time
to be that simple :o)
The wing effects, flaps effects and changed airflow on the tail section all play
their part. The upwash effects on tail plane could vary dramatically with speed,
flap setting, angle of attack, and height above ground.
Most people (myself included) were told in training that ground effect always increase
lift. As the references illustrate that statement should be qualified
with the provision that the angle of attack needs to be small enough.
With low wing aircraft in particular, the proximity of the trailing edge of the
flaps to the ground can work in one's favour if the lift coefficient is small
enough, but could just as well have exactly the opposite effect if one is not
careful with angle of attack.
The bottom line is that unless these adverse factors are avoided, any or all of
them can contribute to the craft and/or nose gear coming down faster than one
would want or expect. Each pilot will naturally develop their own way of dealing
with these effects, but understanding of the various parameters at play can
only be beneficial.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=336321#336321
Message 5
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Subject: | Re: Landing the KIS TR-1 |
I may be wrong but it seems to me that this is looking for a complex reason for
a very simply issue. As designed the main gear is too far aft. I think most
if not all of the problem is once the mains touch down they impart a huge nose
down moment due to their placement too far aft of the CG. I do not think anyone
has had a real issue holding the nose up when flying even in low ground effect.
I think the issue is only after the mains contact.
I also very much suspect the diagram and equation. I would really like to see
the theory, math and experimental data behind it. To me it looks like a suspect
empirical equation that seem to be way too popular in some aircraft design
textbooks and in many papers. Not that empirical equations are not useful. They
are! But you really need to be careful when applying them especially at one
end or the other as in this case.
But even if the equation is correct I very much doubt the KIS achieves much more
than 1.8 Cl even in the flapped area so this should still not be an issue.
Again, I could be wrong. And I am sorry if I am stepping on any toes but just
wanted to express a counterpoint.
Mark
-----Original Message-----
>From: BlueSkyFlier <bleuskyfly@teledynamix.com>
>Sent: Apr 6, 2011 5:27 AM
>To: kis-list@matronics.com
>Subject: KIS-List: Re: Landing the KIS TR-1
>
>
>Of particular interest in the diagram which illustrates changes in lift coefficient
in ground effect [attached to previous message above] is the tendency for
lift to drop away when less than 20% of wingspan away from the ground if the
CL > 2.
>
>With full flaps the TR-1 wing can apparently achieve CL > 2 if the angle of attack
is steep enough. In fact, when holding off with full flaps at high angle
of attack in close proximity to the ground it is likely that this unexpected drop-off
effect could be encountered - not to mention the contribution of adverse
tail plane effects.
>
>It therefore seems important to keep the angle of attack fairly conservative.
This can be done by flying the main gear into touch with a fairly low angle of
attack and comfortable speed (probably > 60 kts) . Once the gear is down the
nose can be pulled up gently to generate maximum drag (the TR-1 will fortunately
not easily lift off again without power).
>
>(The equation from which the lift coefficient chart attached above was created
is attached below for interest. The TR-1 aspect ratio being less than 7 will
tend to exacerbate the unwanted effects.)
>-- ** --
>
>--------
>_________________________________________
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=336265#336265
>
>
>Attachments:
>
>http://forums.matronics.com//files/ground_effect_lift_equation_211.jpg
>
>
Message 6
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Subject: | Re: Landing the KIS TR-1 |
Several years ago, Julian Bone did a rather complete study of the
airflow effect of the KIS wing fairing. It appears from a book by
Stinton, page171, that if the wing fairing needs about an 8 inch radius
instead of the ~3 in radius it has. With the ~8 inch radius, the
airflow over the tail will not be turbulent and the nose will not drop
unexpectedly. Julian modified his plane accordingly and it solved the
problem. I found the Stinton book very interesting. (I think the title
was "The design of an Airplane." I loaned my copy to another builder so
have to trust my memory on the title so I may not be right.). Hope this
sheds some more light on the issue. Larry
On 4/6/2011 4:48 PM, BlueSkyFlier wrote:
> --> KIS-List message posted by: "BlueSkyFlier"<bleuskyfly@teledynamix.com>
>
> Hi Graham,
>
> Unfortunately it is never just one thing. Far too much going on at the same time
to be that simple :o)
>
> The wing effects, flaps effects and changed airflow on the tail section all play
their part. The upwash effects on tail plane could vary dramatically with
speed, flap setting, angle of attack, and height above ground.
>
> Most people (myself included) were told in training that ground effect always
increase lift. As the references illustrate that statement should be qualified
with the provision that the angle of attack needs to be small enough.
>
> With low wing aircraft in particular, the proximity of the trailing edge of the
flaps to the ground can work in one's favour if the lift coefficient is small
enough, but could just as well have exactly the opposite effect if one is not
careful with angle of attack.
>
> The bottom line is that unless these adverse factors are avoided, any or all
of them can contribute to the craft and/or nose gear coming down faster than one
would want or expect. Each pilot will naturally develop their own way of dealing
with these effects, but understanding of the various parameters at play
can only be beneficial.
>
> Regards,
> Alfred
>
> --------
> _________________________________________
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=336321#336321
>
>
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