You  guys with the high gross weights better be
real careful with turbulent air penetration speeds 

Joe, Et Al,

 

Some interesting numbers:

 

Suppose a L-IV G load limit is +4.4 to -2.2 with a Gross Wt of 3550, a stall speed of 65 Kts and a calculated Va of 138 Kts.

 

Suppose further that you increase the Gross Wt to 4550 (1000 #s) or a 28% increase.  This would lower the G load limits to +3.2G and -1.6G (72% of the original). 

 

At such a Gross Wt, the stall speed (Vs) is increased to 74 Kts as calculated by the (SQRT(New Gross divided by the Old Gross)) times Old Vs. 

 

The maneuvering Speed (Va) can be computed as the (SQRT(G limit)) times Vs so that the new Va is reduced to 132 Kts.

 

Landing Loads:

 

The landing load varies with the square of the rate of descent.  A higher gross weight requires a higher approach speed and, if the same glide slope is used, a higher rate of descent and a higher touchdown speed.  There is a calculation for the landing load factor, but it relies knowing the effective stroke of the struts - non-existant on a IV-P, but very useful on a II-P equipped with Ong's Debongers.

 

Anbody change their colored airspeed indicator marks when they change the Gross Weight?  And, the collorary query - Anybody fly their Lancair in the Green arc outside the traffic pattern? Huh?

 

All computations are from "Aerodynamics for Naval Aviators" Which leads to the last question - How can someone mess with their aircraft and not own such a reference?

 

 

PS My diet has succeeded in reducing my aircraft landing weight by two bowling balls, one more to go.  Climb performance is better, too.