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Which sustainer system would you chose for your sailplane?



 
 
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  #91  
Old January 15th 16, 01:36 PM posted to rec.aviation.soaring
krasw
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Default Which sustainer system would you chose for your sailplane?

On Friday, 15 January 2016 01:16:21 UTC+2, Jonathan St. Cloud wrote:
Was wondering how the Arcus E's (electric motor from Lange) are selling compared to the gas engine model?


Since Lange and Schempp are not in best terms (to put it mildly), Quintus and Arcus E are pretty much buried. Arcus E is a nice glider but propulsion system is not free of maintenance or problems.
  #92  
Old January 15th 16, 09:38 PM posted to rec.aviation.soaring
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Default Which sustainer system would you chose for your sailplane?

On Thursday, January 14, 2016 at 11:06:50 PM UTC, kirk.stant wrote:
On Thursday, January 14, 2016 at 4:19:13 PM UTC-6, J. Nieuwenhuize wrote:
IMHO, this plus a small 4-stroke generator of 10-20 hp is the perfect system:
https://www.facebook.com/gpgliders/v...5333550523888/

No noticeable drag if it fails to start, electric reliability and extreme range due to the generator.


Looks nice, but could the drag caused by all those doors (even closed) not equal the drag of a closed FES prop?

Speaking of FES, why not have a single blade? Counterweight in the spinner (it's been around for a long time), fold the prop into a recess under the nose of the plane, cover with a door if you want to be really Gucci...

Kirk
66


There would have to be something far wrong with the fit of aft fuselage engine doors before they caused the same drag as a FES prop. The flight test of the Lak FES that has from time to time been cited as showing minimal drag actually shows around 4-8 kph difference for the same glide angle with the vents open (as would be normal during most gliding) - about one generation of design difference. Diagram on page 7:

http://www.front-electric-sustainer....A%20FES_en.pdf
  #93  
Old February 19th 16, 08:51 PM posted to rec.aviation.soaring
JCK
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Default Which sustainer system would you chose for your sailplane?

On Sunday, September 23, 2012 at 6:55:26 AM UTC+1, Luka Žnidaršič wrote:
Dear gliderpilots!

Manufacturers are not completely sure which is the way to go. So here you can vote for your favorite sustainer system:

http://www.front-electric-sustainer.com/voting.php

Thank you,

Luka


It's interesting to see all your perspectives.
Personally, instant action without trim change wins every time....
Having witnessed a number of near misses, waiting for pylon extraction/engine firing - not to mention how the added pressure to pilot workload affects judgement. Sorry, for me it's a no-brainer.
The only real issue (for me), is the matter of span/vs weight sufficient that 13.5m span is enough?

Thanks

John

  #94  
Old February 25th 16, 07:15 AM posted to rec.aviation.soaring
2G
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Default Which sustainer system would you chose for your sailplane?

The FES has an apparent advantage in higher reliability and, perhaps, lower cost, as well as less maintenance. An engine powered sustainer has a potentially longer self-retrieve distance. Jet powered sustainers have an uncertain reliability. These motors must be spun up to a very high RPM for starting. The motors themselves are not certified for aircraft use. I know of one pilot who landed out in a very bad area when his jet failed to start after 3 attempts (miraculously neither the glider or pilot suffered any damage).
I personally won't have a sustainer. I fly a lot in Utah and Nevada, and the sustainer probably won't get me over the mountain ranges I have to cross, or even get me to a landable field that may be 50+ miles away. But most pilots don't fly in this challenging environment.

Tom
  #95  
Old February 25th 16, 11:26 AM posted to rec.aviation.soaring
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Default Which sustainer system would you chose for your sailplane?

About jet sustainers, it is not true to say that they are not cerified for aircraft use, the M+D (JS1) and PSR (Ventus) jets are EASA certified. As regards the need to be spun to high rpm to start - what is the issue there? Given that the turbines run at 75,000 to 100,000 rpm they have got to get up there somehow. The M+D jet is only spooled up to 8,000 rpm by the electric motor before the fuel system takes over (in two stages). 8000 rpm is nothing remarkable for an electric motor.

Lastly, we can't meaningfully judge the reliability of jets based on the experiences of pre-certification installations during the development stage - which includes all the JS1 installations prior to November 2015. My jet was installed under South African experimental type certificate. I think that the turbine and firmware are at or very close to the certification spec and so far I have had no failed starts out of 44 attempts.

In general I think that failures of all types of sustainer generally arise from ancillary components ( e.g. fuel pump, spark plugs, carburettor diaphragm etc) and electrical issues (e.g. relays, connections etc) and electric glider motors certainly have potential reliabilty vulnerabilities.
  #96  
Old February 25th 16, 12:38 PM posted to rec.aviation.soaring
Casey[_2_]
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Default Which sustainer system would you chose for your sailplane?


In general I think that failures of all types of sustainer generally arise from ancillary components ( e.g. fuel pump, spark plugs, carburettor diaphragm etc) and electrical issues (e.g. relays, connections etc) and electric glider motors certainly have potential reliabilty vulnerabilities.


I think the reliability of a FES would be more reliable than conventional motors due to less parts. However, over the long term a concern I would have about FES would be water/dirt/debrie in the motor and electrical components, assuming that not all are shielded and even then the deterioration over time. I would think that all gliders and motors that are 20-30 yrs old have had wiring, rubber tubing, and other non corrosive components replaced. A solid aluminum/metal engine can be rebuilt and wiring/tubbing replaced. But what about FES? I know the batteries are not an issue due to life expectancy and replacement. But what is the life expectancy of FES motor? How about the build up of dirt and debris from aero tow? Can the FES be air blown off or washed with water?

I really like and think the FES is great and the future but long term maintenance is key to resale ability and market.
  #97  
Old February 25th 16, 02:08 PM posted to rec.aviation.soaring
Surge
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Default Which sustainer system would you chose for your sailplane?

On Thursday, 25 February 2016 13:38:56 UTC+2, Casey wrote:
I think the reliability of a FES would be more reliable than conventional motors due to less parts. However, over the long term a concern I would have about FES would be water/dirt/debrie in the motor and electrical components, assuming that not all are shielded and even then the deterioration over time.


It all depends on the design and materials but people are happy to drive EV's (like one's from Tesla) through mud, water and other harsh environments for years on end without trouble.
Or gliders see a bit of dust for a few seconds once or twice per weekend so I'd hardly worry about it.
I've seen brushless motors run for years in extremely harsh environments without any maintenance and servicing. If the design is right, a brushless electric motor should outlast a combustion engine many times over even with zero maintenance.
  #98  
Old February 25th 16, 02:11 PM posted to rec.aviation.soaring
Surge
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Default Which sustainer system would you chose for your sailplane?

On Thursday, 25 February 2016 13:38:56 UTC+2, Casey wrote:
I think the reliability of a FES would be more reliable than conventional motors due to less parts. However, over the long term a concern I would have about FES would be water/dirt/debrie in the motor and electrical components, assuming that not all are shielded and even then the deterioration over time.


It all depends on the design and materials but people are happy to drive EV's (like one's from Tesla) through mud, water and other harsh environments for years on end without trouble.
Our gliders see a bit of dust for a few seconds once or twice per weekend so I'd hardly worry about it.
I've seen brushless motors run for years in extremely harsh environments without any maintenance and servicing. If the design is right, a brushless electric motor should outlast a combustion engine many times over even with zero maintenance.
  #99  
Old February 25th 16, 02:53 PM posted to rec.aviation.soaring
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Default Which sustainer system would you chose for your sailplane?

On Thursday, February 25, 2016 at 1:11:48 PM UTC, Surge wrote:
If the design is right, a brushless electric motor should outlast a combustion engine many times over even with zero maintenance.

"should" - but I know of a case where that is not so, which is why I suggest caution before accepting very optimistic claims about electric glider reliability.
  #100  
Old February 25th 16, 05:55 PM posted to rec.aviation.soaring
Renny[_2_]
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Default Which sustainer system would you chose for your sailplane?

On Thursday, February 25, 2016 at 6:53:37 AM UTC-7, wrote:
On Thursday, February 25, 2016 at 1:11:48 PM UTC, Surge wrote:
If the design is right, a brushless electric motor should outlast a combustion engine many times over even with zero maintenance.

"should" - but I know of a case where that is not so, which is why I suggest caution before accepting very optimistic claims about electric glider reliability.


Well, let's see..Nothing really is 100% reliable in this world especially in the world of sustainers and self-launchers. At home if I flip a light switch I cannot be 100% sure that the light will come on...Now, it probably will and it is probably 99.99% reliable, but there is no real guarantee and things can go wrong....

I brought the first FES on a LAK-17b into the US over 4 years ago. I have started it many dozens of time (I always start it on the ground before flight as a pre-flight check). It has never failed me, but I also know that the next time it might not start. What I also know is that if does not start I am still a "pure" glider and there is no additional drag penalty to worry about, so I can just proceed and hope for a thermal or if not, simply make a normal landing.

We all know there are no guarantees, but when it comes to reliability and simplicity IMHO I continue to strongly favor the FES over any other sort of sustainer system. Now, tomorrow someone may develop a better mousetrap, but for me and for now, the FES is the "answer."

Finally, on the maintenance question, there essentially is no maintenance for the FES. I fly in New Mexico and have not seen any dirt or dust issues. I realize 4 years is not too long a period for an evaluation, but I will report back in the coming years if any maintenance issues surface.

Thanks - Renny
 




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