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Date: Sun, 18 Jul 2010 20:45:46 -0400
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Subject: Re: [LML] 320/360 CG and Pitch Sensitivity
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Scott -

I wasn't suggesting that you were hung up on CG as percent MAC.  Your reve=
lation that the POH expresses allowable CG range this way caught me by sur=
prise.  I'm still building and the builders manual expresses CG as inches=
 aft of datum.  So I don't really read the POH yet.  (My bad.)  Plus, in=
 my work I'm used to CG being expressed as a Station Number (also inches=
 aft of datum).  But if the POH uses %MAC then that's how we should talk=
 about it, I suppose.

What's truly amazing, however, is that there are two different limits in=
 the same handbook!  I'll take your word on this because my POH is in the=
 hangar.  I am aware that there were two forward limits established for th=
e 320 series.  As I understand it, the forward CG was revised to "allow"=
 a more forward CG after Orin Riddell turbocharged his 360 and had a CG we=
ll forward of the previous limit.  When it turned out that it was just fin=
e, the factory revised the forward limit to match.  I don't know if that=
 farther forward CG is limited to large tails only -- that would make sens=
e if it were.  I think I have the factory newsletter that addresses this.=
  I'll look for it.

Per your flight test comment, yes, I agree that we should verify the aft=
 limit of our individual airplanes as part of our initial flight testing.=
  The factory limit may not be comfortable for all of us, and the time to=
 find this out is in a controlled VFR flight test -- not flying home in ha=
rd IFR with a passenger.  (I have flown a sailplane at the aft limit and=
 I was NOT a happy camper.  It was controllable but it took considerable=
 pilot compensation.  All future flights were ballasted for a less aft CG.=
)

- Rob Wolf


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<font color=3D'black' size=3D'2' face=3D'arial'>
<div>Scott -</div>


<div>&nbsp;</div>


<div>I wasn't suggesting that you were hung up on CG as percent MAC.&nbsp;=
 Your revelation that the POH expresses allowable CG range this way caught=
 me by surprise.&nbsp; I'm still building and the builders manual expresse=
s CG as inches aft of datum.&nbsp; So I don't really read the POH yet.&nbs=
p; (My bad.)&nbsp;&nbsp;Plus,&nbsp;in my work&nbsp;I'm used to CG being ex=
pressed as a Station Number (also inches aft of datum).&nbsp; But if the=
 POH uses %MAC then that's how we should talk about it, I suppose.</div>


<div>&nbsp;</div>


<div>What's truly amazing, however, is that there are two different limits=
 in the same handbook!&nbsp; I'll take your word on this because my POH is=
 in the hangar.&nbsp; I am aware that there were two forward limits establ=
ished for the 320 series.&nbsp; As I understand it, the forward CG was rev=
ised to "allow" a more forward CG after Orin Riddell turbocharged his 360=
 and had a CG well forward of the previous limit.&nbsp; When it turned out=
 that it was just fine, the factory revised the forward limit to match.&nb=
sp; I don't know if that farther forward CG is limited to large tails only=
 -- that would make sense if it were.&nbsp; I think I have the factory new=
sletter that addresses this.&nbsp; I'll look for it.</div>


<div>&nbsp;</div>


<div>Per your flight test comment, yes, I agree that we should verify the=
 aft limit of our individual airplanes as part of our initial flight testi=
ng.&nbsp; The factory limit may not be comfortable for all of us, and the=
 time to find this out is in a controlled VFR flight test -- not flying ho=
me in hard IFR with a passenger.&nbsp; (I have flown a sailplane at the af=
t limit and I was NOT a happy camper.&nbsp; It was controllable but it too=
k considerable pilot compensation.&nbsp; All future flights were ballasted=
 for a less aft CG.)<br>
</div>


<div>- Rob Wolf<br>
</div>


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

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