Today's Message Index:
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1. 07:49 AM - Re: Re: Longtudinal Stability of KIS TR-1 (Mark Kettering)
2. 08:45 AM - Re: Longtudinal Stability of KIS TR-1 (BlueSkyFlier)
3. 08:54 AM - Re: alfred (BlueSkyFlier)
4. 06:00 PM - Re: Re: alfred (Richard Trickel)
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Subject: | Re: Longtudinal Stability of KIS TR-1 |
I did geometry based stability calculations for both the TR1 and TR4 and they had
good margins (except LP in pitch) in all axis when operated in the CG range
specified in the manual. In fact after both my calculations and those done by
Vance it was determined that the allowable aft CG limit could be slightly expanded.
A student at calpoly that I advised for their senior project made a computer
model of the TR4 and used Nastran and the stability module to evaluate
stability on the TR4 and again had good margins (except LP in pitch) in all axis.
The only issue was the X plot and this just showed a problem with the main
gear placement. Keep in mind that all of this was geometry and calculation
based and not based on experimental data. Of course many pilots including a
few test pilots have flown the TR aircraft. I do not know of any issues with
stability but no real stability flight test data has ever been taken that I know
of.
LP is long period and many aircraft at or near their aft CG are not stable in LP
with the stick free and some are not even with the stick fixed. Even a Cessna
150 is not with stick free. Maybe this is what the PFA/LAA means by not stable
longitudinally.
But there is an issue with stick force both in terms of balance and in terms of
just stick force per G. This lack of stick force also can effect longitudinal
stability free stick. Using a spring pitch trim system is also not good for
longitudinal stability free stick. I would stick with a trim tab.
Mark
-----Original Message-----
From: Richard Trickel
Sent: Apr 18, 2011 3:06 PM
Subject: Re: KIS-List: Re: Longtudinal Stability of KIS TR-1
The longitude stability on the plane is pretty good. It was tested out by many
pilots and satisfied FAA requirements in test by Dave Morse. (Test Pilot) Actual
technical information I don`t know. That was a long time ago. I always though
the netural point of mac was the most aft CG location some where around
31%. But rember I am not an engineer. Scott/Mark some help here. The LAA (PFA)
made a statement that the plane was not stable based on what results. This
is the same outfit that would not license a Cruiser which has 4 seats. It
was only licensed as a two seater. These are the experts there. I paid a lot
of money for extra documentation for them for nothing.
--- On Sun, 4/17/11, Scott Stearns <sstearns2@yahoo.com> wrote:
From: Scott Stearns <sstearns2@yahoo.com>
Subject: Re: KIS-List: Re: Longtudinal Stability of KIS TR-1
Martin Hollmann did the basic structural sizing. Vance did some engineering and
wrote the manuals. Some of the metal parts were copied from the first generation
lancairs as I remember.
My impression is that the aerodynamic design was basically doing what looked right,
which can be surprisingly effective with a conventional airplane like we
have.
Scott
--- On Sat, 4/16/11, Larry David <lgdavid@roadrunner.com> wrote:
From: Larry David <lgdavid@roadrunner.com>
Subject: Re: KIS-List: Re: Longtudinal Stability of KIS TR-1
I believe Vance Jaqua was involved. Unfortunately, he passed away a
couple of years ago. I can guarantee that if he were still alive, he
would have loved being involved in these discussions. Larry
On 4/16/2011 2:08 PM, BlueSkyFlier wrote:
> --> KIS-List message posted by: "BlueSkyFlier"<bleuskyfly@teledynamix.com>
>
> Does anyone know who originally did the aerodynamic design of the KIS airframe?
>
> And how to get hold of him of course :o)
>
> Thanks,
> Alfred
>
>
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Message 2
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Subject: | Re: Longtudinal Stability of KIS TR-1 |
Thanks for the information above Mark. Good to hear that the aft CoG margin is
not too critical/sensitive. The LAA opinion about 'marginal' longitudinal stability
is indeed with regard to long period, but I was taught that the pilot is
supposed to control that anyway.
I know of one instance where a TR-1 autopilot installation got out of sync with
the LP and caused a few anxious moments, but it ended well and the owner subsequently
installed a OFF switch for the autopilot on the stick.
On the TR-1 I bought the LAA imposed a requirement on the builder to install a
'down spring' on the elevator - this was a bungee chord which pulled the elevator
down. I did not like that and 'rendered it ineffective' after which it felt
much better on the stick and I could fly it at various speeds without messing
around with the trim all the time.
With the 20 to 25 landings I did in the TR-1 it always behaved well even if I didn't
(by dropping it steeply and then pulling it up strong and short). As Scott
and Mark pointed out the only apparent weakness is that the gear position generates
a pitching moment if the touchdown is somewhat less than gentle. That
can be fixed with relative ease.
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Thanks Rich.
You confirm what I suspected - that the Pulsar operation has never built a Tr-1
wing. I have now pulled the plug on the idea of getting a new wing from them.
I'm going to buy another plane - have my eye on a CT2K if I'm lucky enough to get
it. It has the range, useful load and speed I'm looking for.
Regards,
Alfred
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Alfred
Don`t give up the ship untill you=B4ve sand bag tested the wing to limit lo
ad.- This wing is really built overly strong and I think that you may be
loosing out by not testing it.- And it is so cheap to do.
Even if you do buy another plane testing the wing would be an excelent expe
rience.- LAA may be surprised.-
DOWN SPRING on the elevator Makes a lot o stupid sense.- Let go of the st
ick and she dives.- PFA???????
rich
--- On Tue, 4/19/11, BlueSkyFlier <bleuskyfly@teledynamix.com> wrote:
From: BlueSkyFlier <bleuskyfly@teledynamix.com>
Subject: KIS-List: Re: alfred
Thanks Rich.
You confirm what I suspected - that the Pulsar operation has never built a
Tr-1 wing.- I have now pulled the plug on the idea of getting a new wing
from them.
I'm going to buy another plane - have my eye on a CT2K if I'm lucky enough
to get it. It has the range, useful load and speed I'm looking for.
Regards,
- - - - - - Alfred
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