VMCA and V1

[chiplight2005]

Can anyone tell me what the relationship is between VMCA and V1?

Cheers!! :ok:

[expedite08]

VMCA- Minimum control speed on the ground. It Drecreases with increased pressure alt.

V1- A take off safety speed. At a point before V1 if the critical engine fails the take off should be aborted, if at or above V1 the aircraft should continue the take off on one engine (After this point there will not be enough runway left to bring the aircraft to a halt safely, hence the take off must be contuinued). Just as a note all multi aircraft perf calcs are based on one engine out.

[Hour Builder]

Mate your definitions are wrong

VMCA- Minimum Control Speed in the AIR

V1 is descision speed, not take off safety speed. The latter is V2.

HB

[littco]

V1 must equal or exceed VMCG .. Thats the relationship


And to be precise:

VMCA is the minimum airspeed at which the airplane may be controlled in roll along the longitudinal axis with the critical engine failed, full thrust on the operating engines, and a maximum 5 degree bank toward the operating engines

[Alex Whittingham]

There is no relationship, but, for Class A...

V1 must be ≥ VMCG
VR must be ≥ 1.05 VMCA and
VR must be ≥ V1

If you think about it, none of these imply a relationship between V1 and VMCA unless you can also imply a relationship between VMCA and VMCG. Several threads on Tech Log suggest you can't. There are some dodgy JAA performance questions which imply you can.

[Nathan Parker]

which the airplane may be controlled in roll along the longitudinal axis

That isn't the FAA definition:

25.149 VMCis the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane with that engine still inoperative and maintain straight flight with an angle of bank of not more than 5 degrees.

[transfer jack]

Here is an Illustration showing the V speeds of the take off and other stuff:
http://www.pilotsreference.com/Data/Download/PilotsReference_Checklist_V3_1.pdf