What's your favorite youtube speedpass?

On 1/23/2014 7:18 AM, kirk.stant wrote (w. some snippage):


http://www.youtube.com/watch?v=2S7T81LbvIs

Nice pass!

A question for all you aero majors out the when pulling up at high
speed, should you lead with the flaps, or follow with them?

In this vid, pilot pulls, then lowers flaps after speed has dropped. My
understanding is that it is more efficient to lower flaps (from cruise to
zero, then positive as you slow) during the pull, and my experience
somewhat bears that out (higher alt gain with a good pull and simultaneous
flaps).


Neither lead nor follow?

Here's an attempt at one of those potentially worthless - in the sense that
for all practical purposes it can be neither effectively measured nor
implemented in real time - responses that might just shed some theoretical
light upon one's flying techniques...

If we - for the purposes of a pullup - define "efficiency" as "least
aerodynamic drag possible per time instant" (since both drag and gravity
oppose the ship's ability to trade kinetic energy for height) then the answer
to the question obviously (!) is the flaps should be placed in whatever
position minimizes aerodynamic drag for that instant's speed...think polar.

Complicating factors almost certainly include time and flap position, since
for any given (ever-increasing) amount of flap deflection (below the
separation angle of attack) the wing section can generate greater total lift,
which for a fixed-weight condition will be proportional to "wing developable
G." So, will a shorter time at high G (and drag) - meaning a shorter time to
change pitch angle from (say) "descending through pitched up" - result in
greater speed at the start of the ascent than a "theoretically most
aerodynamically efficient (longer-in-time) configuration" through the same
angular change?

I don't know, but my suspicion is aerodynamic efficiency would trump. In any
event, if we take "the rapid pitch-up" scenario to an extreme, various
fighters can demonstrate that a rapid pitch-up is a great way to bleed energy
and speed (think "the cobra maneuver").

As foe Joe Glider Pilot, this is a great example of one (ideally, many)
test(s) being worth ten thousand considered opinions! Kids, don't do this test
in the pattern...

Bob - it's still winter... - W.

On Thursday, January 23, 2014 8:18:36 AM UTC-6, kirk.stant wrote:
A question for all you aero majors out the when pulling up at high speed, should you lead with the flaps, or follow with them?

Flaps are to follow lift coefficient. As lift coefficient goes up, flaps go down. For absolute lowest drag, flaps should go down as you pull, then go back up once you are on the climbing path. A bit more negative than they would be at the current speed, as you are at less than 1 g. As you round off on the top, flaps go to the 1 g position for your current airspeed. Similarly, as you push over to leave, flaps should go negative, as you are lower lift coefficient. Set them to match speed as you reach your desired cruise.

Watch Champions of the Wave. I think it is cockpit video of Uli Schwenk in his 22. Watch his hand and the flaps as he pushes and pulls.

As to lead or follow, it has been shown that you can control pitch with flaps. But, it is also known that the elevator is a much better way to control pitch. I say, use the elevator, follow as close as you like with the flaps. For me, I don't pull hard enough to warrant pulling the flaps down in a pull. My hand is on the handle, and as I slow down, the flaps move from full negative to where I want them when I round out on top.

Steve
ZS

My second favorite: http://www.youtube.com/watch?v=RZIYmHnK_r8

MY FAVORITE: https://vimeo.com/31524242

:-)

On 23/01/14 13:08, Andrew Brayer wrote:
here's mine:

http://www.youtube.com/watch?v=2S7T81LbvIs


http://www.youtube.com/watch?v=qqlGip0ff7s

On Thursday, January 23, 2014 9:52:53 AM UTC-5, Tom Gardner wrote:
On 23/01/14 13:08, Andrew Brayer wrote:

here's mine:



http://www.youtube.com/watch?v=2S7T81LbvIs





http://www.youtube.com/watch?v=qqlGip0ff7s

yeahhhhhh. that one is pretty good... like really good.

nice long low one.

http://www.youtube.com/watch?v=N1sta1GMQxM

Me in my Genesis 2 - Water Dump
http://youtu.be/ZQWhEjwRIMk

http://www.youtube.com/watch?v=SIdX6...C403FD6B13DC13

^ if you don't watch any of the others, you have to catch this one.

not on YouTube but my favorite low level gliding clips are pretty much all contained in the short film "Dawn Flight"

Gary says:

http://www.youtube.com/watch?v=CKhnU-6GEgg