Mailing List lml@lancaironline.net Message #51401
From: jkezele@juno.com <jkezele@juno.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] gross weight for LNC2
Date: Sat, 09 May 2009 17:18:52 -0400
To: <lml@lancaironline.net>

I look at this subject a little different.  First, I must state that I am not an aeronautical engineer ( but I do keep Daniel Raymer's test "Aircraft Design: A Conceptual Approach" as part of my just for fun books).  I recall that Lancair had a picture of a static load test to 9G.  The loads with respect to fight dynamics and static are not the same.  So if the designed GW was 1685 lbs then any GW about the designed GW would be a fraction of the the original designed load factor.  For example  1685 X 9G = 15,165 lbs, solve for 1916 lbs and you would get about 7.9 G static.

The published Flight load limitation data for 1685 lbs and calculations similar to above for 1916 lbs is as follows.

 

1685 Lbs

1916 Lbs

Flaps Up

+4.5g

-2.3g

+3.96g

-2.02g

Flaps Down

+2.5g

-2.0g

+2.2g

-1.76g

at 1350 lbs published load limitations:

 

1350 Lbs

Flaps Up

+6.0g

-3.0g

I don't see it as simple as if IT will take off then I am good to go!  I see it as, if I choose to fly over the designed GW then I am decreasing my structural margin of safety (factor of safety).  Now these are approximates and I have not taken the time to crunch the numbers with respect to wing loading and increased GW with respect to climb and glide ratios, maximum ceiling, Takeoff and landing distances, braking coefficients, inertia loads, gust factors and others.  Perhaps someday I will sit down and build a good V-n diagram, for now this will have to do.  Have fun building and flying.

Respectfully,

John Kezele

LNC2 (who knows)



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