On Mon, 06 Mar 2017 16:07:36 -0800, Jim wrote:

On Monday, March 6, 2017 at 10:16:37 AM UTC-8, Dan Marotta wrote:
Crab to stay over the runway until you have enough altitude to clear
obstacles, e.g., wind sock should the tug drift downwind. The tug
should also crab so you'll both be flying clean, as Tom said. After
you've got sufficient altitude, say 50-100 feet, slide back behind the
tug.

On 3/6/2017 11:05 AM, wrote:
On Monday, March 6, 2017 at 9:48:13 AM UTC-8,
wrote:
However, doesn't crabbing the glider add a lot more drag to the
towplane/glider combo?
No, a slip creates drag. A crab is clean.

--
Dan, 5J

This is likely just a consequence of poor flying technique but I seem
unable to sustain a crab behind the tow plane without holding a fair
amount of up-wind rudder. The pull of the tow plane seems to pull the
glider's nose out of the crab otherwise.

Seems reasonable to me: if you're on track, i.e. your CG's velocity
vector is pointed at the tow-plane's CG, your nose hook is upwind of that
track and the towplane's tail hook is downwind of it. IOW the tension in
the rope is trying to rotate you round your CG so you point at the
towplane's tail. If the rope tension wins you'll be way out of position,
so it follows that you need to hold sufficient upwind rudder to prevent
the rope pulling you round and to keep your velocity vector aimed at the
towplane CG.

The amount of rudder deflection needed depends on what type of glider
you're flying.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |