@nadler.com wrote:
On 3/19/2021 8:26 PM, Brian wrote:
Excuse me while I turn the short "Always release on Wing Drop" into a long discussion. I least my discussion is long. But like the "Impossible Turn" for power aircraft I suspect the real answer is when you really start to analyze it we find "it Depends" or "when in doubt release" but help me educate myself and others about what is really going on here.

I have been hearing the release immediately on wing drop for over 30 years.
Yet Winch launching almost always becomes part of the conversation almost immediately during the conversations, but I have I don't recall any conversations on Winch vs Aero Tow, or Grass vs Paved launches or even Towplane type (high power vs low power) with respect wing drop on launch, does any of this make a difference? It would seem to me wing wheels vs skids would be a factor as well.
I have watched numerous aerotows off of pavement where the wing hits the pavement drags maybe 10 feet at most, and the glider maybe changes heading 10 degrees at most and then the wing comes back up and the glider repositions behind the glider and proceeds on its way. This is usually attributed to the glider hitting the propwash of the towplane. Having nearly a 1000 hours in a glider with wimpy ailerons I have had my share of wing drops under this scenario and never felt it was an issue or any worse than a no wing runner take off. In fact I recall only one glider releasing when the wing dropped under this scenario which then resulted in the wing tip continuing to drag and turn the glider off the runway into a runway light resulting in some leading edge damage to the wing. IMO if he had flown the glider for another second or two it would have been an uneventful launch. But that is just my opinion, he was PIC.

I understand Winch launches happen a lot faster with a lot more energy than most (if not all) aerotows and releasing immediately makes sense for Winch Launches.

I can also see that when launching off of Non-paved surfaces that releasing immediately on wing ground contact probably makes sense unless perhaps the plane has large wing wheels or it is a very smooth surface. But I have never heard any discussion about that, and It might be a good discussion for those of us that normally aerotow off of paved runways.

I also agree that anytime the heading change of the glider exceeds about 10 degrees one should release immediately regardless if the wing touches the ground or not. On narrow runways this should be pretty obvious because anything more than that you are probably going off the runway anyway. but even launching off wide tarmacs or runways one should still release.

But in the kind of Launch I do the most, Aerotow off of a paved runway. These are much lower energy than a Winch launch and as a result a wing drop is more likely. if there is very little heading change with the wing drop, Should we really be releasing immediately or should we wait a second or two for the controls to become effective which they nearly always do.

Adding more risk factors to consider is it pretty much a given that CG hooks are a higher Risk of Loss of control.
Do High power vs Lower power towplanes affect the risk? Which is better or worse?
Does holding the tail down (back elevator) during the early part of the takeoff roll change vs raising it early help? Pro. tailwheel will help resist turning tendency, Con, may delay aileron effectiveness.

If one is considering not releasing immediately we/they should develop a risk assessment for doing so.

What Have I not considered here?
Brian, there are a lot of factors, including at least:
- tip wheels/skids
- surface drag
- water ballast
- tug acceleration
- hook location (no, a nose hook will not save your ass, despite proponents)
- wind direction and strength
- glider type
- spoiler and flap setting
- dumb luck

So... Do you feel lucky???

So back to my risk assessment...IMO..

- tip wheels/skids - Skids and shorter = increased Risk
- surface drag = More Drag = Increased risk
- water ballast = Heaver wings = Increased Risk
- tug acceleration = I don't know. Once the wing drops, things will happen slower with a low power tug, a high power tug seems like it has more prop wash to cause the wing to drop in the 1st place and the energy in t he system is building faster, so I think I am leaning toward a High Power tug = maybe an increased risk
- hook location (no, a nose hook will not save your ass, despite proponents) CG hook = Increased risk.
- wind direction and strength = cross winds = increased risk, less headwind = increased risk.
- glider type = a consideration for sure but takes some experience to know if higher or lower risk.
- spoiler and flap setting = again likely glider dependent but I know a lot of people start with spoilers extended to prevent wing drop. would think less flap would be better. takes some experience to know.
- dumb luck - The whole point of taking a hard look at the details., How many increased risked factor might apply.

here's a couple more
Rope Length = I would think a shorter rope would = increased risk, more propwash to cause drop
Brake Capacity = poor braking capacity = increased Risk
obstructions to the side of launch area = present = increased Risk