V2 vs V2GA on the CRJ7

[CRJ2]

Hello CRJ-pilots,

1.) Why is V2GA on the CRJ7 different to the V2 for climb? (on the CRJ2 they are the same)

2.) What bankangle are you allowed to fly at V2GA with adequate (15°) overbank-protection?

I'm in the opinion that you may fly turns with max. 15° bank (like at V2) but some people in our company are in the opinion that you can fly 25° bank with 15° overbank-protection.
Who is right now?

We have to fly some missed approach turns with 25° bank due to mountainous terrain. So I would fly them with V2GA + 10!?


What speed would you set on the speed-bug at V2 when you have to fly 25° bank for missed approach or contingency-procedures? V2 (V2GA) or V2 +10 (V2GA + 10)?

Thank's for the help!

Best regards.

[issi noho]

Dont fly your machine and I've never heard of V2GA but I think the speed you're looking for is referred to as approach climb speed. V2 is a calculated TO safety speed so effectively once you have passed it on TO it nolonger exists however since pilots are happy with the name and what it implies and it is conveniently printed in speed books etc and there is a box for it on the EFIS it is convenient to continue to refer to it during GA particularly during flap retract scedule OEI. Perf on most regional jets during GA OEI is such that to fly V2 would not meet the obstacle clearance criteria so speed is reduced to App Clmb spd to improve the gradient (is yr V2GA less than V2?) prior to level segment. If this is the case then it is a reduced bank spd. 25 degs plus 15 overbank generally refer to flap manoevre speeds.

[CRJ2]

The difference between V2 and V2GA depends on the weight. At high weight (near max landing) V2GA it is about 5 to 8 kts higher than V2 and on very low weight V2GA is up to 10 kts lower than V2.

[mutt]

issi nono

You are correct, V2GA is commonly known as Approach Climb limit speed, the CRJ700 AFM lists it as:

Approach Climb Speed. Target climb speed to be attained during a go-around with one engine inoperative.

1.) Why is V2GA on the CRJ7 different to the V2 for climb?

As one is for takeoff and the other is for landing, you will find that the required gradients, configurations and thrust are different.

Mutt

[Old Smokey]

Not familiar with your aircraft, but V2(min) may be as low as 1.2 X Vs (or less), whereas Approach Climb Speed is 1.3 X Vs.

"Why is V2GA on the CRJ7 different to the V2 for climb? (on the CRJ2 they are the same)" - Perhaps because the Performance Engineering people for the CRJ2 opted for higher than V2 min (common practice to improve obstacle performance), whereas perhaps they opted for the lower speed option on the CRJ7 (common practice to improve Field performance).

Regards,

Old Smokey

[Mad (Flt) Scientist]

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.