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Hi,
I've been looking through some aviation dictionaries on the net and there are several definitions for V2. From what I understand, V1 is the maximum speed at which it is possible to stop safely on the runway. VR is the speed at which it is safe to take off but I am unsure of V2.
Can anyone clarify this for me pleaase?
Cheers
from what I though V1 was the minimum takeoff safety speed. VR is the rotation speed. And I think V2 is the takeoff target speed.
I think v2 is target takeoff speed, because if i am in a lesson with rod at FS he said you rotated at v2 witch is good
Ok thanks 
That is good information, but what is the math behind it? How is V2 calculated? I know that I can calculate the proper approach speed for a given AC by multiplying 1.4 times the Vso.
I have no clue how V2 is calculated. I find it out by using aircraft charts and the POH.
Guest
V2, the takeoff safety speed, is that which accounts for obstacle clearance and terrain avoidance. At takeoff thrust, or a computed lower thrust when required for noise abatement, a certain maximum rate of climb is available, and is dependent on airspeed.
It's easy to imagine that at a higher airspeed, a higher rate of climb is available. V2 is the minimum speed at which the takeoff procedure can be safely executed. Most procedures dictate flying at V2 + some margin, 10-15 knots, for increased safety and performance.
V1 is the speed at which you won't be able to abort your take-off. If you pass V1, you HAVE to take off, no matter what happens.
Vr is the speed at which you rotate. You can usually take off at Vr, but it's not advisable.
V2 is the speed at which you will continue your take-off and climb, even if you lose an engine. Most aviation manuals dictate a V2+5 knots take off (correct me if I'm wrong here).
As for the math behind it all, I don't have it at hand, but they take into consideration:
a) The weight of the plane.
b) The conditions (for example icing V speeds are very different than sunny speeds).
c) something else I don't remember.
Could someone tell me how to calculate v speeds and APP speeds becouse I usauly have a FMC to calculate or just use flight notes
It depends on which aircraft you're looking for tables for.
This is the table I use for flying 777s:
http://www.jersey-va.co.uk/Aircraft-specs/boeing_777.htm
But I do think that this should give you everything else you need:
http://www.jersey-va.co.uk/Aircraft-specs/aircraft_spec_page.htm
Simply look up your grossweight and this will giveyou all the reference speeds you need (as well as some other tips on flying).
In a nutshell these V speeds are based on aircraft weight, airfield altitude, temperature and runway length/slope.
Remember V1 as decision speed. Up to V1 you will keep your hand on the throttles and if you have an emergency the throttles can be quickly closed, reverse selected if appropriate etc. At and above V1 there is not enough runway to stop safely using all appropriate "stopping devices"! Therefore you must go....unless you have double engine failure in a twin! At V1 your hand moves off the throttles and both are on the control column, this stops you from closing the throttles if you get a warning of some sort...if your hand was on the throttle it would be second nature to try and stop and at this point you can't!
VR is rotate speed, try rotating before this and you will scrape the tail in most cases. Too late and you may run out of tarmac.
V2 is TO safety speed which is what you can use to climb at initially until acceleration altitude. At this speed even with an engine out you should be safe.
Remember this is in a nutshell!
PH wrote:
In a nutshell these V speeds are based on aircraft weight, airfield altitude, temperature and runway length/slope.
Remember V1 as decision speed. Up to V1 you will keep your hand on the throttles and if you have an emergency the throttles can be quickly closed, reverse selected if appropriate etc. At and above V1 there is not enough runway to stop safely using all appropriate "stopping devices"! Therefore you must go....unless you have double engine failure in a twin! At V1 your hand moves off the throttles and both are on the control column, this stops you from closing the throttles if you get a warning of some sort...if your hand was on the throttle it would be second nature to try and stop and at this point you can't!
VR is rotate speed, try rotating before this and you will scrape the tail in most cases. Too late and you may run out of tarmac.
V2 is TO safety speed which is what you can use to climb at initially until acceleration altitude. At this speed even with an engine out you should be safe.
Remember this is in a nutshell!
Aah thank you
