Mailing List lml@lancaironline.net Message #49062
From: <Sky2high@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Small tail vs. large tail
Date: Wed, 01 Oct 2008 22:54:53 -0400
To: <lml@lancaironline.net>
Mark,
 
Please try Lorn's resolution, no more than 25 degrees of flaps - see if that gives you all the elevator authority you need.
 
Grayhawk
 
PS  Getting grayer eachday................
 
In a message dated 10/1/2008 3:27:14 P.M. Central Daylight Time, mjrav@comcast.net writes:
Hi Scott,
I can't put my hands on the numbers but from memory, they match yours closely.
My heavier motor matches your harmonic gizmo.
And, that's why there is a less than perfect landing if I get sloppy and put all 8 gallons remaining fuel in the header.
 
I almost always use full flaps but the throttle works great for improving elevator authority.
 
Mark
----- Original Message -----
Sent: Tuesday, September 30, 2008 10:47 AM
Subject: [LML] Re: Small tail vs. large tail

Mark,
 
Even more interrrrresting........
 
What is your empty weight CG?  Mine is 20.8"  Also, with a 150# pilot and 8 gal in the header my CG would be out of the forward envelope at 23.4"" (12% MAC).  BTW, I have a 12# harmonic damper on the flywheel along with the heaviest Hartzell prop. 
 
What is your flap setting for these landings?  Moving the flaps up somewhat can change the pitch authority and I wonder if you have tried using the flaps to assist in elevator authority.
 
Scott
 
In a message dated 9/29/2008 12:14:46 P.M. Central Daylight Time, mjrav@comcast.net writes:
I suppose I qualify at 150 lbs.
Std 360, battery in the footwell, Hartzel CS prop.
 
Generally, I make a point to NOT have all fuel in the header on a lightweight landing.  Having it 1/4 to 1/2 full is safe enough.
What happens is that I run out of aft stick travel in the flare and will have a hard landing if I'm not very close to wheels down.
The further foreward the CG, the faster the landing speed must be.  Mostly, it's just hard on the tires.
 
The problem was aggravated by the Hartzel AD requiring a beefed up prop hub.  The prop shop claimed only a 1/2 lb increase but it felt like more to me.  I think the new hub puts the prop a little further forward as well.
 
Also, check that you actually get full elevator travel according to the build manual.  Those last few degrees of up elevator are critical here.
 
An obvious solution might be to move the battery aft but the aft CG range has other problematic issues as well.  This way gives me the widest utility.
 
Once again, the higher performance Lancair design is a wonderful thing but requires a pilot to do more planning than flying that spam can where you can be more careless about loading.
.
 
Mark Ravinski
360    1447 hrs   1077 of it mine.
 
 
 
 
PS - Is there a really skinny flier out there that was aloft with a heavy prop, no baggage and header fuel only?  How was the landing?  Has everyone calculated the minimum pilot weight to stay within the forward CG?




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