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Kawa rough landing?



 
 
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  #31  
Old September 10th 19, 06:41 PM posted to rec.aviation.soaring
Tango Eight
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Posts: 755
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 1:24:46 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.


https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA


"His last calculation of remaining battery energy was about 20 minutes from DXR,
when he noted about 20% battery life remaining. As he prepared to enter the DXR traffic pattern for landing on runway 26, he noted that the glider's altitude was low. He turned on the electric motor; however, it produced only minimal power and the glider continued to lose altitude until it impacted trees and a house 2.7 miles northeast of DXR."

That one was neither a close call (alas), nor a powerplant failure. Rather an empty battery, due to prior self-launch and cruise, without securing alternatives. Analogous to running out of gasoline. It is not evidence against the claim that FES is inherently more reliable than traditional turbo.. Besides the electric motor starting reliably (as long as one keeps some "fuel in the tank"), there is also no added drag like from the boom of a retractable engine (of any type).


Accident due to (imo) poor procedures, yes. Presuming that the pilot's story is correct on the facts, it also reflects shoddy engineering.

T8
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  #32  
Old September 10th 19, 07:11 PM posted to rec.aviation.soaring
[email protected]
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Posts: 345
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 1:41:04 PM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 1:24:46 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA


"His last calculation of remaining battery energy was about 20 minutes from DXR,
when he noted about 20% battery life remaining. As he prepared to enter the DXR traffic pattern for landing on runway 26, he noted that the glider's altitude was low. He turned on the electric motor; however, it produced only minimal power and the glider continued to lose altitude until it impacted trees and a house 2.7 miles northeast of DXR."

That one was neither a close call (alas), nor a powerplant failure. Rather an empty battery, due to prior self-launch and cruise, without securing alternatives. Analogous to running out of gasoline. It is not evidence against the claim that FES is inherently more reliable than traditional turbo. Besides the electric motor starting reliably (as long as one keeps some "fuel in the tank"), there is also no added drag like from the boom of a retractable engine (of any type).


Accident due to (imo) poor procedures, yes. Presuming that the pilot's story is correct on the facts, it also reflects shoddy engineering.

T8


Presumably the "shoddy engineering" you allude to is the implication that the battery gauge was saying 20% but the electric motor refused to run. The story did not mention whether the motor was run further AFTER the 20% reading, and then shut down, before the restart attempt later. It seems unlikely to me that the motor ran OK up to the moment when it was shut down, and then some minutes later refused to start and produce significant power again, as the battery should not have run itself down in-between.

Anyway, gauging how much charge is left in a battery is notoriously difficult, especially when near-empty. I wouldn't count on a 20% battery reading any more than I would count on a 20% gas tank reading - in both cases I'd look for a safe place to land ASAP. On the first trip in the Cessna I had many years ago I landed (after dark, in scattered thunderstorms weather) with only about 10% fuel left (determined from how much fuel was then pumped into the tanks). I learned the lesson not to do that again!
  #33  
Old September 10th 19, 08:12 PM posted to rec.aviation.soaring
Tango Eight
external usenet poster
 
Posts: 755
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 2:11:36 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 1:41:04 PM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 1:24:46 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

"His last calculation of remaining battery energy was about 20 minutes from DXR,
when he noted about 20% battery life remaining. As he prepared to enter the DXR traffic pattern for landing on runway 26, he noted that the glider's altitude was low. He turned on the electric motor; however, it produced only minimal power and the glider continued to lose altitude until it impacted trees and a house 2.7 miles northeast of DXR."

That one was neither a close call (alas), nor a powerplant failure. Rather an empty battery, due to prior self-launch and cruise, without securing alternatives. Analogous to running out of gasoline. It is not evidence against the claim that FES is inherently more reliable than traditional turbo. Besides the electric motor starting reliably (as long as one keeps some "fuel in the tank"), there is also no added drag like from the boom of a retractable engine (of any type).


Accident due to (imo) poor procedures, yes. Presuming that the pilot's story is correct on the facts, it also reflects shoddy engineering.

T8


Presumably the "shoddy engineering" you allude to is the implication that the battery gauge was saying 20% but the electric motor refused to run. The story did not mention whether the motor was run further AFTER the 20% reading, and then shut down, before the restart attempt later. It seems unlikely to me that the motor ran OK up to the moment when it was shut down, and then some minutes later refused to start and produce significant power again, as the battery should not have run itself down in-between.

Anyway, gauging how much charge is left in a battery is notoriously difficult, especially when near-empty. I wouldn't count on a 20% battery reading any more than I would count on a 20% gas tank reading - in both cases I'd look for a safe place to land ASAP. On the first trip in the Cessna I had many years ago I landed (after dark, in scattered thunderstorms weather) with only about 10% fuel left (determined from how much fuel was then pumped into the tanks). I learned the lesson not to do that again!


The point being made (in answer to Peter's query) is: the extent technology for FES is nowhere near the pretty picture some people got in their head when first discussed, that's all.

T8
  #34  
Old September 10th 19, 09:46 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,149
Default Kawa rough landing?

Tango Eight wrote on 9/10/2019 12:12 PM:
The point being made (in answer to Peter's query) is: the extent technology for FES is nowhere near the pretty picture some people got in their head when first discussed, that's all.


We know about FES failures that lead to accidents, but we don't know about all the
times the motors start without problems. It's plausible that it's starting
reliability can exceed (perhaps by a lot) ICE starting reliability.

--
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
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf
  #35  
Old September 10th 19, 10:10 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 74
Default Kawa rough landing?

Kawa's glider was not a FES system, but a Standard mast/electric motor system.
Dan

On Tuesday, September 10, 2019 at 3:12:59 PM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 2:11:36 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 1:41:04 PM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 1:24:46 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

"His last calculation of remaining battery energy was about 20 minutes from DXR,
when he noted about 20% battery life remaining. As he prepared to enter the DXR traffic pattern for landing on runway 26, he noted that the glider's altitude was low. He turned on the electric motor; however, it produced only minimal power and the glider continued to lose altitude until it impacted trees and a house 2.7 miles northeast of DXR."

That one was neither a close call (alas), nor a powerplant failure. Rather an empty battery, due to prior self-launch and cruise, without securing alternatives. Analogous to running out of gasoline. It is not evidence against the claim that FES is inherently more reliable than traditional turbo. Besides the electric motor starting reliably (as long as one keeps some "fuel in the tank"), there is also no added drag like from the boom of a retractable engine (of any type).

Accident due to (imo) poor procedures, yes. Presuming that the pilot's story is correct on the facts, it also reflects shoddy engineering.

T8


Presumably the "shoddy engineering" you allude to is the implication that the battery gauge was saying 20% but the electric motor refused to run. The story did not mention whether the motor was run further AFTER the 20% reading, and then shut down, before the restart attempt later. It seems unlikely to me that the motor ran OK up to the moment when it was shut down, and then some minutes later refused to start and produce significant power again, as the battery should not have run itself down in-between.

Anyway, gauging how much charge is left in a battery is notoriously difficult, especially when near-empty. I wouldn't count on a 20% battery reading any more than I would count on a 20% gas tank reading - in both cases I'd look for a safe place to land ASAP. On the first trip in the Cessna I had many years ago I landed (after dark, in scattered thunderstorms weather) with only about 10% fuel left (determined from how much fuel was then pumped into the tanks). I learned the lesson not to do that again!


The point being made (in answer to Peter's query) is: the extent technology for FES is nowhere near the pretty picture some people got in their head when first discussed, that's all.

T8


  #36  
Old September 10th 19, 10:36 PM posted to rec.aviation.soaring
Richard DalCanto
external usenet poster
 
Posts: 26
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 9:15:24 AM UTC-6, Tango Eight wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.


https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA


oh, and of course...
http://sustainableskies.org/two-batt...ng-sailplanes/

T8


The two battery fires you linked to were with old style battery packs, and from the information available from FES, the problems have been addressed. So why post this? Are you trying to scare pilots away from potentially safer electric options for some reason?
  #37  
Old September 11th 19, 01:23 AM posted to rec.aviation.soaring
2G
external usenet poster
 
Posts: 614
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 11:11:36 AM UTC-7, wrote:
On Tuesday, September 10, 2019 at 1:41:04 PM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 1:24:46 PM UTC-4, wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

"His last calculation of remaining battery energy was about 20 minutes from DXR,
when he noted about 20% battery life remaining. As he prepared to enter the DXR traffic pattern for landing on runway 26, he noted that the glider's altitude was low. He turned on the electric motor; however, it produced only minimal power and the glider continued to lose altitude until it impacted trees and a house 2.7 miles northeast of DXR."

That one was neither a close call (alas), nor a powerplant failure. Rather an empty battery, due to prior self-launch and cruise, without securing alternatives. Analogous to running out of gasoline. It is not evidence against the claim that FES is inherently more reliable than traditional turbo. Besides the electric motor starting reliably (as long as one keeps some "fuel in the tank"), there is also no added drag like from the boom of a retractable engine (of any type).


Accident due to (imo) poor procedures, yes. Presuming that the pilot's story is correct on the facts, it also reflects shoddy engineering.

T8


Presumably the "shoddy engineering" you allude to is the implication that the battery gauge was saying 20% but the electric motor refused to run. The story did not mention whether the motor was run further AFTER the 20% reading, and then shut down, before the restart attempt later. It seems unlikely to me that the motor ran OK up to the moment when it was shut down, and then some minutes later refused to start and produce significant power again, as the battery should not have run itself down in-between.

Anyway, gauging how much charge is left in a battery is notoriously difficult, especially when near-empty. I wouldn't count on a 20% battery reading any more than I would count on a 20% gas tank reading - in both cases I'd look for a safe place to land ASAP. On the first trip in the Cessna I had many years ago I landed (after dark, in scattered thunderstorms weather) with only about 10% fuel left (determined from how much fuel was then pumped into the tanks). I learned the lesson not to do that again!


It is interesting that the pilot reported "calculating" the energy remaining, but not how the calculation was done. The Electro has a crude bargraph display of energy remaining (it has only 10 bars); why didn't he mention that? Was he assuming he had more energy remaining than the bargraph indicated? The only way to know with any certainty the energy content of a battery is to do a discharge test. This can be done very easily with an FES - you simply operate the motor at full power climb and time the operation to battery depletion. You would also need to do this in a partial thrust situation, as happened in this accident. Compare your actual results with the glider's state of charge display. Then, add a safety margin to this (20% would be reasonable).

He was very lucky to have survived this accident. He penetrated the roof near vertically, but impacted between the rafters. He climbed out of the wreckage on his own and scared the hell out of the home owner:
http://www.kathrynsreport.com/2019/0...ro-n66911.html
His attitude towards the homeowner was indicative of a less than humble person, and not how you handle damage to other people's property.

Tom

  #38  
Old September 11th 19, 02:08 AM posted to rec.aviation.soaring
Tango Eight
external usenet poster
 
Posts: 755
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 5:36:27 PM UTC-4, Richard DalCanto wrote:
On Tuesday, September 10, 2019 at 9:15:24 AM UTC-6, Tango Eight wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA


oh, and of course...
http://sustainableskies.org/two-batt...ng-sailplanes/

T8


The two battery fires you linked to were with old style battery packs, and from the information available from FES, the problems have been addressed.. So why post this? Are you trying to scare pilots away from potentially safer electric options for some reason?


And the manufacturers were saying what, exactly, when those fire starters were offered for sale? Were they saying "oh, we haven't really worked out all the bugs yet and these might catch fire?" No, of course not. They were wrong about their product then. You say they think they've fixed it now. Pardon me for being ever so slightly skeptical.

T8
  #39  
Old September 11th 19, 05:24 AM posted to rec.aviation.soaring
2G
external usenet poster
 
Posts: 614
Default Kawa rough landing?

On Tuesday, September 10, 2019 at 6:08:48 PM UTC-7, Tango Eight wrote:
On Tuesday, September 10, 2019 at 5:36:27 PM UTC-4, Richard DalCanto wrote:
On Tuesday, September 10, 2019 at 9:15:24 AM UTC-6, Tango Eight wrote:
On Tuesday, September 10, 2019 at 11:09:12 AM UTC-4, Tango Eight wrote:
On Tuesday, September 10, 2019 at 7:45:04 AM UTC-4, Peter F wrote:
At 08:05 10 September 2019, krasw wrote:
There has been FES selflauncher accident because powerplant failure and
one
really close call. They aren't any better.


Can you provide links to these incidents?

I would expect them to ba at least 1 order of magnitude better than the
traditional turbo.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

oh, and of course...
http://sustainableskies.org/two-batt...ng-sailplanes/

T8


The two battery fires you linked to were with old style battery packs, and from the information available from FES, the problems have been addressed. So why post this? Are you trying to scare pilots away from potentially safer electric options for some reason?


And the manufacturers were saying what, exactly, when those fire starters were offered for sale? Were they saying "oh, we haven't really worked out all the bugs yet and these might catch fire?" No, of course not. They were wrong about their product then. You say they think they've fixed it now.. Pardon me for being ever so slightly skeptical.

T8


Here is the unvarnished truth: if you buy a newly designed MG you are, in effect, a test pilot. These aircraft have not been thru the testing regime that certificated a/c go thru. If you are worried about this, wait 4-5 years before buying a new model. In particular, battery design is not an art that has withstood the test of time. That said, some manufacturers are more diligent than others at the design and testing process.

Tom
  #40  
Old September 11th 19, 12:01 PM posted to rec.aviation.soaring
Jim White[_3_]
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Posts: 271
Default Kawa rough landing?

At 00:23 11 September 2019, 2G wrote:
? The only way to know with any certainty the energy content of a battery
i=
s to do a discharge test. This can be done very easily with an FES - you


Coulumb counter should do it. Count the coulumbs in and out.

Jim

 




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