maximum V1
 

cannot find information about : maximum V1, what is it. Thanks

Hi,

To the best of my knowledge, if you have a indefinite runway length, the maximum V1 will be VMBE (Max tyre braking speed). Should the runway length be definite and limting, Max V1 will be calculated based on the stopping distance available.

Hope that helps,

Cheers

It seems that lion-g beat me by a micro second, in Singapore we are early risers!

A few thoughts -

.1. V1 must not exceed Vr, but may be equal to it (the B727-200 is a good example),

.2. The maximum V1 used must (of course) allow for Accelerate-Stop within the available ASDA, and allow for continued acceleration to Vr and climb to 35' within the available TODA, both of these considerations being embodied within the 'total package' of Takeoff Performance requirements,

.3. The maximum V1 must consider Brake Energy Limits in the event of a rejected Takeoff (Vmbe),

.4. The Maximum V1 must consider tyre (tire for the Yanks) limit speed, although this will in the majority of cases be governed by Vr (Remembering that V1 may equal Vr).

There's plenty of other considerations for the LOWER limit of V1, not addressed here.

Regards,

Old Smokey

And.... there is also a minimum V1. Some computerized performance programs give you both values, loved it.:)

Min V1 is not some fancy computer-calculated number, but mostly dependant on VMCG.

V1 has to be equal or higher than VMCG and equal or smaller than VR.

Vmcg <= V1 <= Vr <= Vmbe / Vmo?

10:25 local - best you take an afternoon nap to recover! :p

Oversimplication Alert!!!!!!!!

V1min may be considerably higher than Vmcg in some cases.

No. Partially correct.

V1 must be higher than Vmcg (actually must be higher than V1mcg, but the simpler statement is true too).

V1 must be lower than Vr, true.

V1 must also be lower than Vmbe, true.

Not sure what Vmo is doing in there, but sure, Vr must be lower than Vmo, I'll grant you that, though any aircraft where that is a consideration scheduling Vr is a strange beast indeed.

But there's no required relationship between Vr and Vmbe. If V1 were set equal to Vmbe, then Vr could easily be above Vmbe.

So I'd rewrite your relationships as:

Vmcg <= V1 <= Vr [ <= Vmo ]
and
V1 <= Vmbe

but really the Vmo bit is a red herring

lazy typing alert : add a bunch of "or equal to" statements to the text above. mea culpa

Are we not playing with Vef today? Is he on the naughty step?

Vmcg<= Vef

V1= Vef + x where x is a time period defined by the certification standard.

And V1 must not be less than the minimum speed at which we can recognize a critical engine failure, decide to go, and complete the take-off safely, with the critical engine inoperative, reaching V2 and screen height within the remaining TODA.

With a high take-off mass and a short TODA, this requirement may limit V1min, before it becomes low enough for V1<=VMCG to become the problem.