Quote Originally Posted by Ron Blum View Post
The original poster (Waldo) posed a question relative to Vx, Vy and clearing a 50’ ground obstacle (regulation). Angle of climb (with respect to the air) is both irrelevant to aircraft performance and the original posters question/statement.

Flying an airspeed of Vy will produce the highest rate of climb (altitude gain per time).
Flying an airspeed of Vx will produce the highest angle of climb (altitude gain per distance travelled)
If you accept that Vy has a lower angle of climb than Vx, then what's the discussion about? Angle of climb (with respect to the air) is what will determine angle of climb over an obstacle on the ground.

The OP said:

"In so doing I found that in all cases Vy yielded a steeper flight path angle than Vx."

This is the incorrect part. Vy, as you know, does NOT yield a steeper flight path angle than Vx. This is what all of us took exception to, and it has nothing to do with distance over the ground, just distance (as defined by TAS per unit time).

Because the OP used inappropriate information to attempt to DERIVE the Vx climb rate (since that information is not in any POH), he then got inaccurate data for climb performance over a 50' obstacle, which was his original goal. Conflating inappropriate data was the problem with his calculations. If he actually tested for Vx and Vy in a particular airplane and then measured the altitude above a 50' obstacle, he'd realize that climbing at Vx would get him higher over an obstacle than Vy would.

And the OP stated, with respect to the POLL:

"Poll is: agree Vy angle > than Vx
disagree, Vy angle not > Vx, Vx is greater than Vy
Other: ?"

As you've clearly articulated, the angle of climb at Vx is ALWAYS higher than the angle of climb at Vy - there can be no other answer. And that's NOT a function of wind, ground, or anything else.