Mailing List lml@lancaironline.net Message #52709
From: Rod Pharis <rpharis@teamimc.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Strength vs. stiffness
Date: Thu, 20 Aug 2009 09:28:32 -0400
To: <lml@lancaironline.net>
Lynn,
 
Could you sketch on a photo or illustration of the Legacy approximately where you added the "Reno Race Mod," how many layers and wheather BID or Uni?  I am planning to at least stiffen the roof above the baggage compartment, and the fuselage between the luggage bulkhead and the vertical stabilizer with diagonal Uni to increase torsional stiffness.
 
Rod
----- Original Message -----
From: farnsworth
Sent: Wednesday, August 19, 2009 5:34 PM
Subject: [LML] Re: Strength vs. stiffness

The aft fuselage reinforcement that was done on my Legacy was done on the recommendation of Greg Cole (One of the designers of the Legacy). He directed where and how much to strengthen the aircraft. He said with that modification the aircraft is good up to .6 Mach. I have had mine to .56 Mach at FL230. It has been done on several Super Legacys. I think you can order the “Reno Race Mod” through Lancair if you tell them at the time you order a Legacy kit. They will incorporate the mod in the kit when it is manufactured.

 

Our planes are good, but they do have areas that can be improved and Greg has improved the Legacy. Even if you don’t want to race, I have confidence that Greg Cole knows what he is doing and my Legacy is stronger (safer) because of the race mod.

 

Lynn Farnsworth

Super Legacy

TSIO-550 Powered

Race #44  

 


From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Steve Colwell
Sent: Wednesday, August 19, 2009 6:03 PM
To: lml@lancaironline.net
Subject: [LML] Strength vs. stiffness

 

I don’t pretend to know anything about flutter, strength or stiffness other than you can get in trouble “improving” the strength of an airframe.  From what I have read over the years, unless a proven problem exists you might create one by making changes.  One example is a 6’ tapered fishing rod that will support say 25 lbs..  If you clamp it to a table with one foot hanging over the edge, it will break with a 10 lb. load.   Even I can understand that example.  All the factors that affect flutter are way beyond me.

 

Tail shake is occurring every time a Legacy applies full power for takeoff.  If you want to see for yourself, watch the tail of a Legacy (or probably most highly powered prop planes) when the brakes are set and full power is applied.  The tail is moving around A LOT.  Apparently it’s not a problem since the high time airframes seem to be doing just fine.  After thousands of hours maybe our composite airframes will have structural problems (like the Cessna 210

 I understand).

 

Steve Colwell  Legacy

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