Stall spin during aero tow? Std cirrus

Thanks for all the comments and personal stories guys. it really helped. The safety video from a competition that was posted here was very helpful it explained a lot!

At 00:42 08 August 2018, Dave Nadler wrote:
On Tuesday, August 7, 2018 at 7:01:38 PM UTC-4, Tom BravoMike wrote:
How come nobody mentions positive faps in this discussion?
Am I missing sth? Are they useless in situations when the tug is too
slow?
If so, why? Please illuminate me.

Flaps add a lot of drag. The first time I had a stall on tow,
I pulled down landing flaps, which recovered the stall and
almost put the towplane in the trees. I eased off the flap
and somehow he sped up without hitting anything.

Bear in mind that the tug pilot also has a release and if you do something
that endangers him he's perfectly entitled to use it.

The simple facts are that heavily loaded modern gliders need a ****load more speed than older light wingloading gliders.
Some tug pilots seem to not know the difference.
When I am in the tug I reckon I can feel when the glider needs speed but after many tows from the glider end I can see that not all tug pilots can see this.
Brief your tuggie or potentially die! I have lost one friend and seen some crappy launches at comps.
The JS1C at max weight needs a pawnee to fly at 75kts for the glider to feel good, my ASG29 needs at least 70kts, club tuggies might be more used to
Blaniks or the like that will climb OK at 55-60. Use the flaps as instructed by the flight manual.

On Tuesday, August 7, 2018 at 10:45:24 AM UTC-4, Steve Koerner wrote:
This subject comes up every few years on RAS and that's a very good thing.. Long ago there was a death on tow with a heavily watered ship that I'm pretty sure was caused by this.

I have already posted a couple times in the past about my own near death experiences I have had dangling from a slow towplane at a remarkably low stalled tow position while slamming the stick back and forth against the stops in Ventus 1 and in ASW27. When this is happening at a very low altitude (as it was), then releasing is not an option.

Several have pointed up the necessity of communicating with the tow pilot.. I think it preferable to communicate in writing. Except at contests, I always make sure that the tow pilot has been handed my written towing instruction when I have water ballast. Here's a link to my little towing instruction sheet: https://goo.gl/PwVu71

Steve, you should not assume the tow planes airspeed indicator is calibrated or accurate. You might consider modifying your note to say "minimum" or "at least" and once safely on tow ask to slow down if need be.

My breifing usually includes " Have you towed ballasted ships before" IF SO, please tow me the same as (insert here a comparable speed and weighted ship here), the tow pilot will understand that relationship alot better than just a speed as every tow plane I have towed behind or flown is alittle different.

CH

Make sure when your briefing the tuggie that you speaking the same language ie. KNOTS or MPH. There a fair difference between 60 mph and 60 knots. If the tuggie isnt on the same page with you, you might end up in the sagebrush at the end of the runway.

On Wednesday, August 8, 2018 at 1:18:26 PM UTC+1, PGS wrote:
On Tuesday, August 7, 2018 at 10:45:24 AM UTC-4, Steve Koerner wrote:
This subject comes up every few years on RAS and that's a very good thing. Long ago there was a death on tow with a heavily watered ship that I'm pretty sure was caused by this.

I have already posted a couple times in the past about my own near death experiences I have had dangling from a slow towplane at a remarkably low stalled tow position while slamming the stick back and forth against the stops in Ventus 1 and in ASW27. When this is happening at a very low altitude (as it was), then releasing is not an option.

Several have pointed up the necessity of communicating with the tow pilot. I think it preferable to communicate in writing. Except at contests, I always make sure that the tow pilot has been handed my written towing instruction when I have water ballast. Here's a link to my little towing instruction sheet: https://goo.gl/PwVu71

Steve, you should not assume the tow planes airspeed indicator is calibrated or accurate. You might consider modifying your note to say "minimum" or "at least" and once safely on tow ask to slow down if need be.

Even if the tug ASI is properly calibrated by ground testing it may not read accurately in flight because of very poor static inputs or the use of cockpit static. As an ex JS1c 21m owner I got into the habit of not only telling tow pilots the speed I wanted (absolute minimum of 70 knots as read by the glider ASI) but also exchanging ASI readings with them on tow. Every Pawnees I was towed by had an ASI that over-read by 5-7 knots compared to my reading. The same was found using other types of glider behind Pawnees. The Eurofox tugs that are getting popular in the UK has similar errors.

I think that this may be a significant safety issue.

Although perhaps not widely used in the US, Chipmunks and Robins seemed to me to have much more accurate ASI systems.

I tell our newer towpilots that with the big gliders and gliders with water, it is almost impossible to tow them too fast and way better to be on the fast side than the slow side.

This of course is the opposite from towing slow speed trainers which are much happier slower than faster. These are what our towpilots usually tow, so when the Nimbus 3 full of water is pulled out to the line, they need to shift from a slow bias to a fast bias.

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'

A very comprehensive report, and a fair conclusion.