Launch with a crosswind

This is an excellent discussion of “how to” launch from a field where there is a strong crosswind, and there isn’t a person to serve as wing runner during the launch.

Posted to the hgcgroup@yahoogroups.com

Mon, Jul 15, 2013 at 7:04 PM, Ramy wrote:

After calling for a retrieve while still in the air, I realized the wind was very cross and relatively strong, with occasional tumble weeds blowing across the runways.So instead of landing Harris ranch with its narrow runway, I opted for the desolated new Coalinga with wider runway. Landing was not too much of a challenge, but after landing I realized the wind was mostly 90 degrees 20 knots, gusting maybe 25. And I then feared that my adventure wasn’t offered, as I never launched before in such strong cross wind. It was reassuring to have Charlie towing me, with his calm instructions on how to take off in such conditions, which worked perfectly, so here are the steps we took, which may work for nose hook but perhaps not for CG hook:

1 – We positioned the glider on the downwind (left) side of the runway, with the nose slightly pointing up wind (which surprised me, but Charlie assured me it is better).
2 – Up wind right wing on the ground (that’s where wings wheels come very handy)
3 – Tow plane took slack completely, while I ensure up wind wing remained on the ground).
4 – Full opposite rudder (left rudder) which I think is the most essential to prevent the glider from weather vaning at the beginning of the role).
5 – Stick full backward at the begging (new to me) to keep the tail on the ground for the first few seconds to prevent weathervane.
6 – Full trust at take off for max acceleration and prop trust.
7 – Keep the upwind wing low but lift a little to prevent hitting runway lights.
8- Keep left (downwind) rudder until the glider actually tries to go left. This is going to take a while and by then you probably in full control and can proceed with a normal tow , still keeping right wing slightly low to track the runway.

Following the above, it ended up to be one of my better cross wind takeoffs, if not the best.
Thanks Charlie for the lesson and confidence.

Ramy

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Here is a posting by Charlie H. in response to the above posting by Ramy:

Tue Jul 16, 2013 12:55 pm (PDT)

Thanks for sharing your experience, Ramy. Your cross country exploits are legend in our region and beyond. Landout experience is a hallmark of the complete pilot.

Some may be wondering the why of pointing the glider nose slightly upwind. First TG (the ID of the glider) was offset about 3 or 4 feet downwind of the center line. Traditional practice calls for glider nose slightly downwind, and this is effective for CG or nearly CG towhooks, as the towrope has no or little directional effect as to weathervaning. But with a nose or nearly nose hook the towrope imparts a strong directional vector, and that momentum is increased with a rapid acceleration. If the glider nose is pointed slightly DOWNwind the towrope would actually accelerate the weathervaning momentum with a nosehook, but the opposite is accomplished if the nose is pointed slightly UPwind. With this positioning of the glider nose, the towpilot brings the rope to a taut condition, applies wheel brakes, increases rpm to 1800 or so and goes to full throttle after brake release. Now an opposing vector to the weathervaning effect exists for a second or two. Full glider downwind rudder is a must initially. Glider stick full back for at least 3 seconds gives a directional stability mitigating the weathervaning effect as the tail wheel is forced down on the pavement until the rudder becomes fully effective.

The slight nose upwind also allows a little better aileron control to keep the upwind wing down before the ground roll starts. The xwind component was actually 70 degrees + or – 5, so with the angle we had roughly 30 degrees of headwind component available for pre-acceleration aileron control. We did not have a wing runner. That is an advantage in this particular situation as an inexperienced runner, or one that does not understand the dynamics can be a hindrance to a safe launch. I find that quite often most runners will hang on to the wing for a moment before releasing, imparting a weathervaning vector to the initial roll in a crosswind. Not having a runner, if the wing would not stay down we would have repositioned to the crosswind runway.

I assessed the safety of this particular launch based on my experience, Ramy’s experience and understanding of the dynamics (he had to rationally agree with my suggestions), the gliders tailwheel type (large pneumatic), wingtip wheel type (low friction, free wheeling), towhook position, and a wide hard surfaced runway.

Each individual aerotow retrieve has multiple factors to consider. Most are inadvisable with a considerable crosswind. The facility at New Coalinga is exceptional.

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