Bash me if you want, but hanging the horizontal, farther back from the
Center of Gravity, creates a longer " lever ", and I personally see no
reason to enlarge it. As Larry would say, your results may vary. John
Shaffer
-----------------------------------------From: "Phillip Matheson via
KRnet"
To: "MS", "KRnet"
Cc: "Phillip Matheson"
Sent: Thursday March 2 2023 4:03:32PM
Subject: Re: KRnet> Horizontal stabilizer kr-2
Mike I totally agree with a standard kr My KR2Ss is longer and wider,
so a larger tail area, as per Mark Langford is a must. The next most
important area is empty CoG. Try and build with the empty CoG on for
even FWD of the plan forward limit. My first kR2 needed min 75 kg
pilot with empty plan to get it into CoG range My new KR2SS empty was
about mid range, so I bit the bullet and made new engine mount and
extended the cowls 3 inches forward. Now I can full load within the
limits Phil Matheson.
Sent from my iPhone
On 3 Mar 2023, at 06:12, MS wrote:
Just noticed the subject of this post is "Horizontal stabilizer
KR-2". My response has been as if the subject was "Vertical Stabilizer
& Rudder". Sorry.
Mike Stirewalt KSEE
On Wednesday, March 1, 2023 at 06:12:56 PM PST, colin hales via
KRnet wrote:
Hi Jamie,
With regards to solid proven advice, I can solidly say, I didn't
extend the fin forward. I don't have any stability issues so my advice
is that there is no need to extend the fin. But if you want to extend
forward the fin an inch or two, I can't see any harm.
But I am blue in the face because I say this until I am blue in the
face, stability is all to do with centre of gravity. The standard KR2
might be pitch sensitive to those who fly jumbo's but there are no yaw
issues with the plane.
Far more of an issue is engine torque. Depending on how much power
you will have will depend on how much corrective rudder you need to
counteract engine torque, adding to the fin isn't going to help that
one bit. Since there is no offset built into the fin, as there is on
many other aircraft, size is not really an issue.
For clarification, some aircraft have the fin offset to counteract
permanently engine torque, so you don't need a rudder trim tab or to
keep so much rudder in when taking off or climbing with full power.
The KR2 fin is set in line with the fuselage centre line for
simplicity. Also, VW engines you need to offset the fin to the right,
Continetal or lycoming, off to the left, because they rotate in
opposite directions. So to save confusion, on such a plane where
engine choice is open, the fin is set down the middle with no offset.
I came across a Midget Mustang where the owner cursed it because he
could never keep it straight on take off. I was asked to look into it
and quickly discovered that the original builder of many previous
owners had put the fin offset bracket on the wrong way. Swapping it
around made the pilot a lot happier.
So my personal advice is to build it light and keep a forward C of G
and keep to the plans. One less issue for your inspector to study.
Where I live, that type of deviation from the plans would require lots
of paperwork.
I know this hasn't answered your question perfectly, but the advice
is sound.
CH. --
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