Stall spin during aero tow? Std cirrus

On Monday, August 6, 2018 at 11:20:51 AM UTC-4, JS wrote:
On Monday, August 6, 2018 at 8:00:52 AM UTC-7, Dan Daly wrote:
On Sunday, August 5, 2018 at 10:49:48 PM UTC-4, wrote:
Have there been stall spins during an aero tow?

Today, I had a very scary aero retrieve. From being towed to fast to-to slow. Anyways the scaries part was when, the tow plane started to climb and to slow. The indicated speed on the glider was 50 knots and decreasing. The glider kept slowing down and sinking under the tow plane into the wake.. By this time the glider felt extremely sloopy and it felt like it was ready to drop into stall. Fortunately as I felt the wing wanting to drop, the tug leveld some and got back to a decent speed.

Yes I did radio the pilot askig for 20 indicated more. And I was attempting to release when I hit the wake, but the release on the standard cirrus is far, and my extention had moved from my legs.

I had to release a couple of times last year; put the first down to new tow pilot. Second... hmmm. When the Pawnee did its annual, transponder (actually encoder) failed, and leak in pitot/static system and a subtly bent pitot tube were found to be responsible. The towplane speed looked good, mine, not so much in a Std class glider with the stick on the back stop, still sinking. When in doubt, release and debrief; multiple times, find what the problem is (I had checked my pitot/static system for leaks too). One problem inexperienced tow pilots cause without thinking is pulling up in lift to use the energy - while the glider is still in the sink surrounding...

A simple improvement, if not a fix:
If it feels sloppy on tow, put in another notch of positive flaps.
Jim

Std Cirrus has no flaps. My Std Class glider has no flaps. Agree flaps work - if you have them.

On Monday, August 6, 2018 at 11:37:11 AM UTC-4, Dan Daly wrote:
On Monday, August 6, 2018 at 11:20:51 AM UTC-4, JS wrote:
On Monday, August 6, 2018 at 8:00:52 AM UTC-7, Dan Daly wrote:
On Sunday, August 5, 2018 at 10:49:48 PM UTC-4, wrote:
Have there been stall spins during an aero tow?

Today, I had a very scary aero retrieve. From being towed to fast to-to slow. Anyways the scaries part was when, the tow plane started to climb and to slow. The indicated speed on the glider was 50 knots and decreasing. The glider kept slowing down and sinking under the tow plane into the wake. By this time the glider felt extremely sloopy and it felt like it was ready to drop into stall. Fortunately as I felt the wing wanting to drop, the tug leveld some and got back to a decent speed.

Yes I did radio the pilot askig for 20 indicated more. And I was attempting to release when I hit the wake, but the release on the standard cirrus is far, and my extention had moved from my legs.

I had to release a couple of times last year; put the first down to new tow pilot. Second... hmmm. When the Pawnee did its annual, transponder (actually encoder) failed, and leak in pitot/static system and a subtly bent pitot tube were found to be responsible. The towplane speed looked good, mine, not so much in a Std class glider with the stick on the back stop, still sinking. When in doubt, release and debrief; multiple times, find what the problem is (I had checked my pitot/static system for leaks too). One problem inexperienced tow pilots cause without thinking is pulling up in lift to use the energy - while the glider is still in the sink surrounding...

A simple improvement, if not a fix:
If it feels sloppy on tow, put in another notch of positive flaps.
Jim

Std Cirrus has no flaps. My Std Class glider has no flaps. Agree flaps work - if you have them.

That was the joke...

Pitch a little slower Jim... we want to be sporting, after all :-).

T8

I agree with Ramy, a fully laden ASG 29 is very intolerant of low tow speeds. As these wonderful gliders begin to fall into the hands les experienced, pilots it needs to become common knowledge that a heavy ASG 29 requires an extra 10 knots of airspeed from the tow plane. I have , and have seen two highly experienced friends struggle with control on takeoff in their 29’s.
We all had thermaling flaps deployed. This is especially true at high density altitudes. 80 knots works nicely. The tow pilot needs to be coached to hold the tow plane in ground effect until that speed is achieved. That can be unsettling to them, especially on hot days at high altitude, so the communication needs to be explicit. As others have said, some Pawnees have inaccurate pneumatics which can lead to pushback from the tow pilot. Any Standard class ship,when heavy, needs that same consideration.
Dale Bush

On Monday, August 6, 2018 at 1:48:53 PM UTC-4, wrote:
I agree with Ramy, a fully laden ASG 29 is very intolerant of low tow speeds. As these wonderful gliders begin to fall into the hands les experienced, pilots it needs to become common knowledge that a heavy ASG 29 requires an extra 10 knots of airspeed from the tow plane. I have , and have seen two highly experienced friends struggle with control on takeoff in their 29’s.
We all had thermaling flaps deployed. This is especially true at high density altitudes. 80 knots works nicely. The tow pilot needs to be coached to hold the tow plane in ground effect until that speed is achieved. That can be unsettling to them, especially on hot days at high altitude, so the communication needs to be explicit. As others have said, some Pawnees have inaccurate pneumatics which can lead to pushback from the tow pilot. Any Standard class ship,when heavy, needs that same consideration.
Dale Bush

Yes, this was exactly my experience in the 29. I almost stalled on tow. The same year I bought a self-launcher and I never had that problem again.

So, your empty hand can mark the map spot where you are.........since it isn't needed for flaps.....;-)

No, not relevant in this thread.
Funny, in my eyes, slow tow sucks in anything.

Yes, I fly a wide range of sailplanes.

Sorry. At least it was after references to ASW20 and ASG29. The trick works in both.
Often laugh at myself for trying to grab the flap handle in a Duo. Doesn't work any better than it would in a Cirrus, except to get a second person laughing.
Jim

That was the joke...
Pitch a little slower Jim... we want to be sporting, after all :-).
T8

A simple improvement, if not a fix:
If it feels sloppy on tow, put in another notch of positive flaps.
Jim

I think the worst I have had was in a contest (upstate NY), ASW-20, maybe 3/4 load of water, summer, weak Citabria towplane.
I felt like I was just barely hanging on. Yes, I radioed the tug but IIRC he had a radio issue that was fine on the ground.

On Sunday, August 5, 2018 at 10:49:48 PM UTC-4, wrote:
Have there been stall spins during an aero tow?

Yes, and fatalities.
Safety brief from minute 14 of this video:
https://www.youtube.com/watch?v=WIZW...TSR0IGIvNSG84Q

I think I forgot in this brief:
If the tow-plane starts to kite up as you are still rolling or just off,
RELEASE IMMEDIATELY.

Be safe out there,
Best Regards, Dave

At 02:49 06 August 2018, wrote:
Have there been stall spins during an aero tow?


An internet search for JA21KAJA2376 should find a Japan Transport
Safety Board report of a 2012 accident where an SF25C was towing a
Discus and the combination ditched into the river next to the airfield.
The report concludes that the Discus stalled on tow.

On Tuesday, August 7, 2018 at 1:45:11 PM UTC-4, Iain Baker wrote:
At 02:49 06 August 2018, wrote:
Have there been stall spins during an aero tow?


An internet search for JA21KAJA2376 should find a Japan Transport
Safety Board report of a 2012 accident where an SF25C was towing a
Discus and the combination ditched into the river next to the airfield.
The report concludes that the Discus stalled on tow.

Interesting report - here is the direct link:
http://www.mlit.go.jp/jtsb/eng-air_r...21KAJA2376.pdf

Uli
'AS'