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Kawa rough landing?



 
 
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  #121  
Old September 22nd 19, 03:18 PM posted to rec.aviation.soaring
[email protected]
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Default Kawa rough landing?

" I ran that thru the translator....blah blah blah"
That was a good one Jonathan, I'm still chuckling.
  #122  
Old September 22nd 19, 08:14 PM posted to rec.aviation.soaring
2G
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Default Kawa rough landing?

On Saturday, September 21, 2019 at 1:49:44 PM UTC-7, Richard DalCanto wrote:
On Saturday, September 21, 2019 at 2:43:24 PM UTC-6, 2G wrote:
On Saturday, September 21, 2019 at 1:24:28 PM UTC-7, Richard DalCanto wrote:
On Saturday, September 21, 2019 at 12:32:23 PM UTC-6, 2G wrote:
On Thursday, September 19, 2019 at 8:27:43 PM UTC-7, Andy Blackburn wrote:
Tom,

I think you misread my post. No one ever practices spins at pattern height and I'd never recommend it. My point was that practicing spins and spin entry and recovery at altitude might save your life should a moment of distraction in the pattern lead to a departure. Never practicing spins at all leads you to trying to figure everything out for the first time at low altitude should the worst happen. Early recognition is half the battle.

Andy

On Thursday, September 19, 2019 at 12:59:47 AM UTC-5, 2G wrote:
Andy,

When you are down low (in the pattern) practice COORDINATED flight - that is what will save your ass, not a low-altitude spin recovery. This is just plain, simple common sense. Pilots, lots of them, who don't do this are getting killed, this is fact. Can you produce a SINGLE pilot who has done such a low altitude save?

Tom

Andy,

I didn't misread your post, but I am certain you misread mine:

"We are all saying the same things, the ONLY difference is the emphasis on priorities. We all say that glider pilots should fly coordinated and be taught spin recognition and recovery. I am only pointing out that this isn't totally working because pilots are still killing themselves with low altitude stall-spins. Personally, this happened to a friend of mine, and I witnessed a second friend very nearly kill himself doing exactly this."

To repeat, spin recognition and recovery training should be taught (and practiced). But I think you would agree that it is far better not to enter the spin in the first place, especially at low altitude. As they say, an ounce of prevention is worth a pound of cure. Here is an attempted spin recovery that didn't work:
https://app.ntsb.gov/pdfgenerator/Re...Final&IType=LA

Tom

I agree that it is better to not spin in the first place. But I would not post that is a spin recovery that didn't work. Based on the report, it doesn't look like the pilot tried to recover correctly (or at all before turning into a spiral dive). I was amazed when I did spin training in Arizona how quickly a glider recovers as soon as you push the stick forward. This guy was flying in a competition with other gliders and had Marijuana, and Valium in his system. Luckily he didn't kill anybody else with his f*ing drug use. You don't want to know what I really think about dirt bags that fly or drive while impaired.


The NTSB stated that a blood sample was unavailable, so whether or not he was impaired could not be determined. If the NTSB couldn't determine that, I know you can't!



Tom


It said that the NTSB did not have blood samples to determine the exact drug levels, but they were definitely in his system. Not the kind of person I want to share airspace with.


The bottom line is the NTSB found that they could not determine impairment - to say he was w/o evidence is uncalled for. Marijuana can be detected in your body a month after last use. Stick to the facts.

BTW, we all know pilots that we would not want to share airspace with.
  #123  
Old September 22nd 19, 09:43 PM posted to rec.aviation.soaring
2G
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Default Kawa rough landing?

On Saturday, September 21, 2019 at 6:27:31 PM UTC-7, BobW wrote:
On 9/21/2019 2:30 PM, 2G wrote:
On Saturday, September 21, 2019 at 6:06:18 AM UTC-7,
wrote:
The main reason motorgliders like the Arcus see such a large decrease in
performance with the mast up is that the engine bay doors remain open,
and they are about six feet long. That's a huge amount of drag. When we
installed jet engines in the Tst-14 and four Arcuses, we had the main
doors close over the engine bay and two small "sub-doors" open around the
engine mount. With the engine extended, we measured the L/D of the Arcus
J (jet) at 38:1. The Arcus M gets 13:1 with engine extended.


The principal source of drag is the prop; the engine bay doors are aligned
with the slipstream, and doesn't matter how long they are, the frontal area
remains the same (very small)...

Because I've long been fascinated with aerodynamic drag, this particular topic
fascinates me, and the above exchange reminds me of a factoid my brain thinks
it has retained which - if retained accurately (too lazy to look it up just
now) - may surprise many a RASident. But first...

If the expression "there's devils in the details" applies anywhere,
aerodynamics fits the bill. And for the Truly Anal (or simply Seriously
Interested), I recommend the late Sighard F. Hoerner's masterpiece book,
"Fluid Dynamic Drag" which can be used to actually do a great job of assigning
numerical relative estimates of the drag contributions being discussed above.

I don't expect to actually make such an attempt, but I'm also not gonna bet
the retirement slush fund on "prop drag uber alles" in this instance, while I
*would* be willing to bet some actual money *against* the broad-brush
statement following the semi-colon of the shorter excerpt above being correct,
especially the "...doesn't matter how long they are..." bit.

Shape matters...a *lot* when it comes to aerodynamic drag. In drag-reduction
terms, whether it's more useful to (say) streamline the front of a
motorcycle/rider combo, or fair the rear may surprise many people. Consider a
theoretical, round, 1"-dia lift strut (think 2-33) vs. a faired version of the
same strut, both operating normal to the airflow, at pattern speeds. How many
RASidents would guess the drag coefficient of the former shape vs. the faired
shape is ... wait for it ...

... == 8X == HIGHER?!? And - like hands in lowball poker, where you only
get worse - it (drag) all adds up!

If I ever get an Arcus M and the POH tells me it has an attention-getting sink
rate with the mast extended and inop engine at pattern speeds, I'm definitely
gonna incorporate some personal testing of that configuration early-on, with
gobs of altitude, in my getting-to-know-the-ship phase...and, in the purely
nut-behind-the-stick sense of things, I don't care *where* the drag sources
may actually be located!!! :-)

YMMV.
Bob W.

---
This email has been checked for viruses by AVG.
https://www.avg.com


Your "analysis" boils down to "I've read a book on aerodynamics so my gut feeling is better than yours." It would actually have been helpful to do actual calculations. 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.

Here are some actual Cd figures for various shapes:
https://www.grc.nasa.gov/www/k-12/airplane/shaped.html
Notice that the flat plate (prop) has a Cd over four times that of a bullet (engine bay door) - at the SAME cross sectional area. A prop is going to have MANY TIMES the frontal area of a set of engine bay doors. Conclusion: your "analysis" is wrong.

Tom

  #124  
Old September 23rd 19, 01:12 AM posted to rec.aviation.soaring
Ben Coleman
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Default Kawa rough landing?

That's interesting and good to know Dan. I had guessed there might be some bad behaviour in landing trim from the comments in the pilot handbook for my 6b, but had not tested it.
Cheers Ben
  #125  
Old September 23rd 19, 04:15 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Default Kawa rough landing?

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
  #126  
Old September 23rd 19, 05:21 AM posted to rec.aviation.soaring
2G
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Default 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
  #127  
Old September 23rd 19, 01:27 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Default Kawa rough landing?

On Saturday, August 31, 2019 at 12:31:32 PM UTC-7, Jonathan St. Cloud wrote:
Not sure how accurate FB translate is, but it appear as if Mr. Kawa had some sort of incident with an electric motor not working and a rough uphill landing. Gas, electric or jet be careful guys!


Have we not leant anything from Bill and Kennth, define "plummet". A MD500 in a 180 degree auto will peg the -3K VSI hard against the stop. But it is not consider "plummeting " just sporting. It is a known and we practice. Same in a glider, know your bird.
  #128  
Old September 23rd 19, 06:57 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Default Kawa rough landing?

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
  #129  
Old September 23rd 19, 07:03 PM posted to rec.aviation.soaring
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Default Kawa rough landing?

So the moral of all this is that motor equiped sailolane fliers should get some 1-26 xc time?
LOL
  #130  
Old September 23rd 19, 07:14 PM posted to rec.aviation.soaring
kirk.stant
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Default Kawa rough landing?

On Sunday, September 22, 2019 at 7:12:50 PM UTC-5, Ben Coleman wrote:
That's interesting and good to know Dan. I had guessed there might be some bad behaviour in landing trim from the comments in the pilot handbook for my 6b, but had not tested it.
Cheers Ben


Well, it's hardly "bad behavior". In landing configuration (gear down, landing flaps), my LS6-b has a bit of a g-break at the stall, but it's not violent or particularly bothersome, and you really have to ham-fist it to get any sort of departure. It's actually kind of fun to play with; it's the only way I can get any sort of incipient spin entry out of my '6. In normal thermalling config (5 or 10 flaps), stall is a non-event due to lack of elevator power. (my CG is around 30% forward of aft limit, I think).

Kirk
2000hrs in my LS6-b without any spin issues.
 




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