wdn Vy and Vx are certification speeds (test pilot territory) not really applicable in day to day flying. They were speeds born of some certification requirement and have, like so many things in aviation, taken on a life of their own.
Think about it. A 50' obstacle
exactly at the end of the TODA.
Think also about how
low 50' is.
You'll be above 50' before the gear is up.
And yet we see pilot after pilot climbing away at Vy to some truly stupid altitudes...500'-1000' or even cruise altitude as often as not...cruise climb seems to be a mystery to many pilots.
It is, in my view, negatively reinforced by the diagrams you see depicting Vy/Vx in sundry publications. Usually a picture of a cessna standing on it's tail climbing over a tree....the scale errors of the diagram make it look like the tree is actually several hundred feet high and that, I suspect, is the psycological factor which starts pilots climbing at Vy to such completely stupid altitudes.
In my Bonanza Vy is 93 kts. Glide speed in the landing config is 90kts and glide speed clean is 110kts. At 93 kts the nose is hauled up so high that the view ahead is severely compromised. If you lose an engine in that attitude you'll be below 90ts in a heart beat and have to lower the nose
dramatically in an attempt to get it back let alone 110kts. At an altitude of say 100' you will merely develope a
very high rate of descent without the time to recover speed and its attendant manouever capability. You will then be faced with the ground arriving to smite thee in the face at some horrifying rate and a almost guaranteed
very heavy
arrival.
In a twin many of the same considerations apply but for slightly modified reasons. If you are climbing away in a typical piston twin at Vy in an effort to get lots of altitude 'quickly' in case of engine failure and you actually lose an engine you will need
LOTS of rudder to control the yaw and need to lower the attitude
dramatically to;
1/. stop further speed decay,
2/. regain a speed which will allow you to climb/maintain height while you sort !!!! out.
Given the
extremely high
oh !!!!!!! factor in typical
real engine failures this is beyond the capabilities of many pilots and, in my view, is exactly how Vmca loss of control accidents happen.
In my Bonanza I get airborne, gear up, gently climb/accelerate to 110Kt asap. If I lose the engine at
any point I need only to lower the nose slightly to maintain speed and look for something soft to hit. Once I actually have 110Kts the aeroplane is truly manoueverable and can look at turning left or right slightly for better opportunities if they exist. At 110kts my wing really comes alive and I get initial climb rates of 1000'/min at 110-120kts...with nice cool CHTs as well
The same applied when I used to fly Barons etc. Accelerate in a gentle climb looking for that cruise climb 'sweet spot' and if you lose an engine you have a nice buffer
above Vyse (and that may
not be the blue radial painted on the ASI. Control initial yaw with rudder (you'll need a lot less at the higher IAS) gently lower the nose a small amount to maintain speed and carryout the recall items- mixture/pitch/power up, wheel ups/flaps up/ identify, verify, feather, fuel.
I have yet to see an airport/airstrip in my career that
required Vy/Vx
Editted for spooling...again.