B777 Min Vr SPD Calculation
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B777 Min Vr SPD Calculation
Referring to the FPPM B777 300ER, The table gives a read out of V1MCG & Vr min.
The variables involved are TEMP(OAT) VERSUS PRESSURE ALT to give above speeds.
If I takeoff at SL at 30 degrees OAT with a/c weight 220T
my Min VR shows 130kts. And at 350T under the same conditions Min VR also shows 130kts (I am not referring to actual VR which is going to obviously much higher compared to 220T takeoff)
My confusions are,
why is the airplane weight not considered in calculating VR min?
Is my assumption correct when I say that Min VR is calculated for tail clearance purposes?
Any info or corrections are welcome.
The variables involved are TEMP(OAT) VERSUS PRESSURE ALT to give above speeds.
If I takeoff at SL at 30 degrees OAT with a/c weight 220T
my Min VR shows 130kts. And at 350T under the same conditions Min VR also shows 130kts (I am not referring to actual VR which is going to obviously much higher compared to 220T takeoff)
My confusions are,
why is the airplane weight not considered in calculating VR min?
Is my assumption correct when I say that Min VR is calculated for tail clearance purposes?
Any info or corrections are welcome.
Join Date: Aug 2009
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MinVR is determined by controllability first and foremost, so VMCG and VMCA. Thus the density altitude is the only factor - technically also the moment arm of the tail...