The aerodynamics of a towplane in a kiting glider situation

On Monday, May 18, 2020 at 11:05:00 AM UTC-4, Tom BravoMike wrote:
On Monday, May 18, 2020 at 2:40:26 AM UTC-5, Marton KSz wrote:
I found this diagram last week:

https://photos.app.goo.gl/nLpWwLHFmgwE5dEM9

Here's my interpretation:

The system of the connected towplane + glider has a center of gravity, somewhere along the towrope, closer the towplane.

When the kiting begins, the system of the two connected masses start rotating around this CG (just like groundlooping a tailwheel aircraft).

However, since the glider is lighter, it rotates faster, which makes the impression that the towplane slingshots it.

Also, the glider has wings, and faster airspeed on the wings means more lift - the glider wants to go even higher.

All the energy for the extra lift + speed has to come from somewhe the supply is the kinetic energy of the towplane. As the kiting aggravates, the towplane drastically slows down. First it runs out of elevator control, then stalls.

That's quite an interesting picture, helping to understand the process and the discussion about the (initially) small angles.
The 800 ft minimum for the towplane to recover from a dive seems a lot. Could speak for using eg. touring motorgliders as tugs in hope they could recover faster.

In my low kiting incident I don't believe it started any more than 350 feet AGL. The 800 ft minimum appears to be if you are at 90 degrees nose down and stalled. I can't say exactly what angle I was at but It was beyond 60 I am sure, I recall no horizon in the wind screen. When the rope broke (which sounded like a mass of sheet metal hitting the ground) I realized I needed proper airspeed before I could fly and I didn't quite have it. I slowly eased out of the dive using what altitude I had and came in with power (which for some reason as I remember seemed a bit hesitant, I'm told maybe the G force on the float in the carb) and recovered slightly below the trees being visible in my peripheral vision off to the left. IF I was over the stand of trees, If it wasn't clear below me I would not have made it. At one point I thought I was going into the trees. That feeling sucks big time.

Walt Connelly
Former Tow PIlot
Now Happy Helicopter Pilot