Kawa rough landing?

On Sunday, September 22, 2019 at 8:15:41 PM UTC-7, Eric Greenwell wrote:
2G wrote on 9/22/2019 1:43 PM:

The bottom line is that the total drag of the 26e prop+mast+radiator+engine bay doors drops the glide from 50:1 to 17:1. At best, what you are arguing about is the relative contribution of these elements - my bet is on the prop being the largest. But the only thing that matters is the total drag..

Don't forget the massive landing gear that puts the wheel and tire almost entirely
outside the fuselage (and it has doors with a frontal section nearly as big as the
engine doors)!

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

That 17:1 figure was with the gear retracted.

Tom

2G wrote on 9/22/2019 9:21 PM:
On Sunday, September 22, 2019 at 8:15:41 PM UTC-7, Eric Greenwell wrote:
2G wrote on 9/22/2019 1:43 PM:

The bottom line is that the total drag of the 26e prop+mast+radiator+engine bay doors drops the glide from 50:1 to 17:1. At best, what you are arguing about is the relative contribution of these elements - my bet is on the prop being the largest. But the only thing that matters is the total drag..

Don't forget the massive landing gear that puts the wheel and tire almost entirely
outside the fuselage (and it has doors with a frontal section nearly as big as the
engine doors)!

I'll have to redo my measurements of years ago. I recall getting about 20:1 in
landing configuration, but I can't find my notes. Who did the 17:1 measurement?

Another data point: In 2008, Dr Jack had the belt break on his 26E, stopped the
engine, but was unable to stop the freely spinning propeller. He wrote "From my
GPS trace the glide ratio during the straight portion of my descent, at around 55
kts in flap 3 with prop spinning, as 18.5"

So, gear up, but prop spinning, he was able to glide about 7 NM to an airport,
then encountered some lift and thermalled up, and briefly considered thermalling
the 11 NM to his home airfield, but decided it was smarter to land. Hardly sounds
like a glider in "plummet mode"?


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

So the moral of all this is that motor equiped sailolane fliers should get some 1-26 xc time?
LOL

On Monday, September 23, 2019 at 1:57:40 PM UTC-4, Eric Greenwell wrote:
2G wrote on 9/22/2019 9:21 PM:
On Sunday, September 22, 2019 at 8:15:41 PM UTC-7, Eric Greenwell wrote:
2G wrote on 9/22/2019 1:43 PM:

The bottom line is that the total drag of the 26e prop+mast+radiator+engine bay doors drops the glide from 50:1 to 17:1. At best, what you are arguing about is the relative contribution of these elements - my bet is on the prop being the largest. But the only thing that matters is the total drag..

Don't forget the massive landing gear that puts the wheel and tire almost entirely
outside the fuselage (and it has doors with a frontal section nearly as big as the
engine doors)!

I'll have to redo my measurements of years ago. I recall getting about 20:1 in
landing configuration, but I can't find my notes. Who did the 17:1 measurement?

Another data point: In 2008, Dr Jack had the belt break on his 26E, stopped the
engine, but was unable to stop the freely spinning propeller. He wrote "From my
GPS trace the glide ratio during the straight portion of my descent, at around 55
kts in flap 3 with prop spinning, as 18.5"

So, gear up, but prop spinning, he was able to glide about 7 NM to an airport,
then encountered some lift and thermalled up, and briefly considered thermalling
the 11 NM to his home airfield, but decided it was smarter to land. Hardly sounds
like a glider in "plummet mode"?


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

I had a non start(pilot induced) the other day in my ASG-29E. I was positioned on down wind for my selected field. Rather than mess with the engine(and associated distraction)I put the gear down and landed normally. Since I usually fly a fairly steep approach, I did not sense any meaningful affect on my landing.
FWIW
UH

wrote on 9/23/2019 12:24 PM:
I had a non start(pilot induced) the other day in my ASG-29E. I was positioned on down wind for my selected field. Rather than mess with the engine(and associated distraction)I put the gear down and landed normally. Since I usually fly a fairly steep approach, I did not sense any meaningful affect on my landing.
FWIW

In my Guide (and here!), I recommend you put the gear down when you are in the
pattern planning a restart. One less thing to forget if the engine doesn't start.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Monday, September 23, 2019 at 10:57:40 AM UTC-7, Eric Greenwell wrote:
I'll have to redo my measurements of years ago. I recall getting about 20:1 in
landing configuration, but I can't find my notes. Who did the 17:1 measurement?

When I had my '26E, I once flew several self launches to pattern altitude, shut down the engine and landed with the prop extended. It was a complete non-event and felt the same as a pattern and landing in an ASK-21. I like to fly a high and steep final so maybe that's why. I probably used less spoiler in the '26E to maintain the same approach angle. I also applied landing flaps sometime between base and final.

When making a "straight in" type final glide with just a couple hundred feet arrival when some distance out, I'd pick a (or already have one in mind) a few miles out if it still looked marginal. I'd then start the engine, make a few orbits over the safety field to gain altitude, then motor home. Once home, I'd retract the engine part way to cool it and make a landing.

I once joined a ASW-20B in an extremely weak thermal, shut down the motor and again lowered it to the slightly extended cooling position. We were pretty much even in climb and even while gliding to another thermal a mile or two away. So my takeaway there is that at speeds around 60 knots, the open engine doors and partly extended engine produce negligible drag.

IMHO, the dire warnings about poor LD on the POH are there to avoid any liability if someone decides to sue after an engine extended mishap. Or to be a bit kinder, like what we tell new glider pilots about thermalling low - stop trying to stay up and just land once at XXXX above ground.

5Z
Now flying ASW-27b

5Z wrote on 9/26/2019 12:21 PM:
lowered it to the slightly extended cooling position.

The "slightly extended cooling position" is about 30 degrees from the fuselage.
There is still all the stuff hanging in the breeze: the propeller, the radiator,
almost the entire mast, and the doors are fully open. It looks dreadfully draggy
to a pilot circling in the same thermal with you, but it's just like Tom says: the
drag is so small, you don't know it's there.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Thursday, September 26, 2019 at 1:13:07 PM UTC-7, Eric Greenwell wrote:
5Z wrote on 9/26/2019 12:21 PM:
lowered it to the slightly extended cooling position.

The "slightly extended cooling position" is about 30 degrees from the fuselage.
There is still all the stuff hanging in the breeze: the propeller, the radiator,
almost the entire mast, and the doors are fully open. It looks dreadfully draggy
to a pilot circling in the same thermal with you, but it's just like Tom says: the
drag is so small, you don't know it's there.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1


Got so concerned with staying under the LAS Class B once, didn't completely put away the ASH26E mast until after a cruise to the second thermal. A bit noisy but no big deal.
Once climbed in the 26 together with a Discus 2. I still had the mast in cooling position, the D2 was "P7". Impressed!

Enjoying Fred Drift this time, Seems like Kawa was being condemned for nothing.
Jim

On Thursday, September 26, 2019 at 1:13:07 PM UTC-7, Eric Greenwell wrote:
5Z wrote on 9/26/2019 12:21 PM:
lowered it to the slightly extended cooling position.

The "slightly extended cooling position" is about 30 degrees from the fuselage.
There is still all the stuff hanging in the breeze: the propeller, the radiator,
almost the entire mast, and the doors are fully open. It looks dreadfully draggy
to a pilot circling in the same thermal with you, but it's just like Tom says: the
drag is so small, you don't know it's there.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Right - here is a flight where I forgot to complete the cool-down process and flew for 3 hours with the prop in that position:
https://www.onlinecontest.org/olc-3....l?dsId=7393456
It is really hard to determine the glide degradation with the prop out, but I am sure there is some.

Tom

On Thursday, September 26, 2019 at 3:21:49 PM UTC-4, 5Z wrote:
IMHO, the dire warnings about poor LD on the POH are there to avoid any
liability if someone decides to sue after an engine extended mishap.

Eric and 5Z - Please don't ASSUME that all gliders are as benign as 26
with motor out and stopped. They are not. You are doing the community a
great disservice by ASSUMING that its not a big problem for some gliders.
Including types with many in service.

Please be safe out there,
Best Regards, Dave