Vick wrote:

hotrod150 wrote:I guess I'm not sure exactly what is meant by "behind the power curve". If lift/drag max is best glide speed, I'm definitely slower than (left of?) that in the scenario I described. "In order to slow down you have to add power" sounds to me like below power-off stall speed.

How about a (better) definition of "behind the power curve"?

Think about it this way, to the right of L/D max pitch sets your A/S and power controls rate of descent (ROD)- just as you said. If you want to fly a slower approach you pitch to capture your desired speed and then adjust throttle to maintain your desired ROD. This will work, in theory, down to L/D max. Once you go to the left of L/D max (also known as "behind the curve" or the region of reverse command) the drag generated by the AOA needed to maintain your desired speed increases dramatically in proportion to the generated lift. So to capture an even slower speed you would have to ADD power to supplement the lift generated by the wing - without additional power you wouldn't be able to maintain your desired airspeed without incurring an undesirably high, or possibly even fatal if you were deep enough in the stall, ROD.

So, again in theory, if you were to determine that you needed to fly an approach at speed X in order to stop on the available landing surface, and speed X is below your L/D max, you would have to fly a behind the curve approach to attain speed X which means you would have to carry power to overcome the drag induced at the necessary AOA. Clear as mud?

This is well precedented in carrier aviation - for example the A-6 and EA-6 flew behind the curve approaches intentionally. In their case it wasn't to get sufficiently slow, it was to keep the engines throttled up sufficiently such that they could maintain the precise glide slope required and ensure they had quick throttle response if they had to wave off. Those old turbo motors had abysmal spool up time from idle.

WSH wrote:Just thinking out loud.

Wouldn't we have to include, overlay, the POWER CURVE as well.

We all operate safely left of the drag curve all the time, Vx for example.

The real danger, at least for MOST piston aircraft, is running out of available POWER to recover.
Or, operating behind the POWER CURVE, not so much the drag curve.

What do you think?

motoadve wrote:once over the landing spot at 3ft high or so,cut all power and raise flaps and we stopped .

Grassstrippilot wrote:Great thread. Gump is right on and summed up well what I remember reading from Sparky. However, I don't think I had heard the idea of adding power in ground effect. Makes perfect sense! Can't wait to go try it out. Thanks for the tip!!

Vick wrote:..... Remember that in level, unaccelerated flight lift equals weight and thrust equals drag.......

Trimtab wrote:182 that comes with a power on approach and uses more power to slow the descent, flare, power off, and squat in the grass.

GumpAir wrote:

Trimtab wrote:182 that comes with a power on approach and uses more power to slow the descent, flare, power off, and squat in the grass.

Squatting is exactly how it feels when it all comes together. The airplane just squats down, and quits moving. It's gentle, easy on the gear (and pax), and you use minimal landing area. Now all you gotta do is figure out how to get out of where you just landed.

Gump