Originally Posted by CRJ2
Hello CRJ-pilots,
1.) Why is V2GA on the CRJ7 different to the V2 for climb? (on the CRJ2 they are the same)
As alluded to by some replies already, the fundamental reason is that one relates to takeoff and one to landing. This causes somewhat different requirements to be applicable to the two speeds, which drives differences between them.
If you compare the CRJ100/200 AFM Performance section with the CRJ700 AFM equivalent, you'll note that the CRJ700 presentation is rather more complex. This is because the limiting criteria for determining speeds for the CRJ100/200 are quite simple - usually, all that matters is stall speed, and everything else pretty much falls out from that. While we could chose the apply higher speeds of course, the actual constraints are simple. Therefore the presentation is also fairly simple and there isn't much variation between the landing and takeoff limitations.
The CRJ700 AFM is rather more complex, and this is because other limitations - arising from minimum control speed and minimum unstaick speed requirements - intrude upon the simple stall speed ratio concerns. The V2GA chart, for example, has the various deviations from the 'normal' 'speed varies with weight' expectation due to VMCL limitations. VMCL is a specific speed applicable only to the landing/go-around case, and may differ from VMCA (which would impact takeoff speeds) depending on the circumstances. To avoid having to define a single V2/V2GA which would necessarily have to conservatively apply all the limitations for both flight phases, it makes more sense to split V2 and V2GA and apply the specific limitations applicable to each case.
That's the 'mechanical' explanation as to why the charts differ. The fundamental aerodynamic explanation almost certainly lies in the differing wing design approaches. The CRJ700 has a slatted wing, and therefore relatively low stall speeds compared to the CRJ100/200 with it's 'unslatted' wing. Therefore it's more likely that the CRJ700 speeds would be affected by concerns other than stall speed, simply because the stall speeds are relatively better.