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Subject: Re: Small tail, MK II tail, CG range
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<<I still recommend adhering to the published CG limits, but when push com=
es to shove there is more wiggle room at the aft end of the range with the=
 larger tail.  Even with that cushion, some have pushed too far.>>

Chris is correct.  The forward CG is generally limited by the ability to=
 flare on landing, i.e., having sufficient "control power" to lift the nos=
e at low speed.  That's a pretty objective measure.  The aft CG is general=
ly limited by handling qualities.  The handling qualities get worse as the=
 CG moves aft.  In this context, "worse" means things like stick-force-per=
-G and short period damping.  Whatever the specific aircraft parameters ar=
e to an aerospace engineer, to a pilot it just gets "squirrely" as the CG=
 approaches the aft limit.

Where the aft limit is, well, that's purely subjective.  What's acceptable=
 to you may not be acceptable to me.  What's acceptable in smooth air may=
 not be acceptable on an ILS to minimums.  It can also be mission-dependen=
t.  What's acceptable for an acrobatic airplane may not be acceptable for=
 a trainer airplane.

In general, the handling qualities are improved as CG moves forward or as=
 tail size increases (although the precise mechanisms are different and it=
's rather an academic discussion anyway).  The main reason we're having th=
is small tail vs big tail discussion is because we all have different thre=
sholds of "good enough". =20

- Rob Wolf
Large tail and proud of it...
Also not flying yet and kinda embarrassed by it...



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<font color=3D'black' size=3D'2' face=3D'arial'>
<div>&lt;&lt;I still recommend adhering to the published CG limits, but wh=
en push comes to shove there is more wiggle room at the aft end of the ran=
ge with the&nbsp;larger tail.&nbsp; Even with that cushion, some have push=
ed too far.&gt;&gt;</div>


<div>&nbsp;</div>


<div>Chris is correct.&nbsp; The forward CG is generally limited by the ab=
ility to flare on landing, i.e., having sufficient "control power" to lift=
 the nose at low speed.&nbsp; That's a pretty objective measure.&nbsp; The=
 aft CG is generally limited by handling qualities.&nbsp; The handling qua=
lities get worse as the CG moves aft.&nbsp; In this context, "worse" means=
 things like stick-force-per-G&nbsp;and short period damping.&nbsp; Whatev=
er the specific aircraft parameters are to an aerospace engineer, to a pil=
ot it just gets "squirrely" as the CG approaches the aft limit.</div>


<div>&nbsp;</div>


<div>Where the aft limit is, well, that's purely subjective.&nbsp; What's=
 acceptable to you may not be acceptable to me.&nbsp; What's acceptable in=
 smooth air may not be acceptable on an ILS to minimums.&nbsp; It can also=
 be mission-dependent.&nbsp; What's acceptable for an acrobatic airplane=
 may not be acceptable for a trainer airplane.</div>


<div>&nbsp;</div>


<div>In general, the handling qualities are improved as CG moves forward=
 or as tail size increases (although the precise mechanisms are different=
 and it's rather an academic discussion anyway).&nbsp; The main reason we'=
re having this small tail vs big tail discussion is because we all have di=
fferent thresholds of "good enough".&nbsp; </div>


<div>&nbsp;</div>


<div>- Rob Wolf</div>


<div>Large tail and proud of it...</div>


<div>Also not flying yet and kinda embarrassed by it...<br>
</div>


<div style=3D"CLEAR: both"></div>
</font>

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