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nuckolls.bob(at)aeroelect
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 Posted: Mon Sep 01, 2014 10:16 am Post subject: Engine restart while airborne . . . |
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At 10:15 AM 9/1/2014, you wrote:
Hi Bob,
I read your book through and I think have understood the basics. It gave me a super know how boost, thanks. Right now I am on the electric schema for a Zenith STOL 750 with Rotax 912 ULS 2.
One thing I do not understand: In no Z-Drawing is the Ignition Switch / Start Button connected to the endurance bus? In case of a failure of the master relay or master switch it is not possible to restart the engine in this configuration as far as I understood the different drawings. Although it might rarely occur that at the same time in flight you need to restart the engine and the main bus is not available (would mean there is a kind of a big problem). But it would surely help to have the security to be able to turn the engine; or may the windmill effect make my need redundant?
Does the 912 engine windmill on a STOL750? I don't know
but the people who are building and flying these airplanes
SHOULD know . . . and this information is best acquired from
the factory.
So is there any reason not to connect the ignition/engine start switch to the endurance bus?
If the main bus is down, this means the battery master contactor is open. So being able to put power on the starter contactor is not very useful whene there is no power for the contactor to control. Sorry for the question you probably already answered many times but I could not access the FAQ Part on your page.
No problem. I'll look into that FAQ link. But in any case, the legacy failure mode effects analysis for light aircraft does not stack multiple failures. The vast majority of engines stop because of fuel starvation. Your pondering of "Plan-B" alternatives would do well to consider all the ways that mechanical failure in the fuel delivery system can be managed . . . the kit folks have probably done this already but you need to understand it. In other words, the elegant answer to your question is: "Minimize or eliminate the reasons that your engine might quit in flight so that you don't find yourself short on the Main Bus power as well!
Bob . . .
Bob . . . [quote][b]
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Mon Sep 01, 2014 4:37 pm Post subject: Engine restart while airborne . . . |
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Bob, Nope, a Rotax is a geared engine and when the engine stops so does the prop. Even the two strokes with relatively low compression compared to the 10.5 to 1 of the 912S series engines bring the prop to a stop PDQ when the engine stops running. Learned this the hard way when the engine on my Kolb quit on a downwind departure. Fortunately I was able to glide back to the runway and miss the idiot in the Baron who was taking off downwind so it ended well. Some new Hanes and a fuel filter and I was good as new.
Rick Girard
On Mon, Sep 1, 2014 at 1:15 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 10:15 AM 9/1/2014, you wrote:
Hi Bob,
Â
I read your book through and I think have understood the basics. It gave me a super know how boost, thanks. Right now I am on the electric schema for a Zenith STOL 750 with Rotax 912 ULS 2.
Â
One thing I do not understand: In no Z-Drawing is the Ignition Switch / Start Button connected to the endurance bus? In case of a failure of the master relay or master switch it is not possible to restart the engine in this configuration as far as I understood the different drawings. Although it might rarely occur that at the same time in flight you need to restart the engine and the main bus is not available (would mean there is a kind of a big problem). But it would surely help to have the security to be able to turn the engine; or may the windmill effect make my need redundant?
Does the 912 engine windmill on a STOL750? I don't know
but the people who are building and flying these airplanes
SHOULD know . . . and this information is best acquired from
the factory.
Â
So is there any reason not to connect the ignition/engine start switch to the endurance bus?
If the main bus is down, this means the battery master contactor is open. So being able to put power on the starter contactor is not very useful whene there is no power for the contactor to control. Â Sorry for the question you probably already answered many times but I could not access the FAQ Part on your page.
 No problem. I'll look into that FAQ link. But in any case, the legacy failure mode effects analysis for light aircraft does not stack multiple failures. The vast majority of engines stop because of fuel starvation. Your pondering of "Plan-B" alternatives would do well to consider all the ways that mechanical failure in the fuel delivery system can be managed . . . the kit folks have probably done this already but you need to understand it. In other words, the elegant answer to your question is: "Minimize or eliminate the reasons that your engine might quit in flight so that you don't find yourself short on the Main Bus power as well!
Bob . . .
 Bob . . . | Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
 - Groucho Marx
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Tue Sep 02, 2014 4:22 am Post subject: Engine restart while airborne . . . |
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At 07:36 PM 9/1/2014, you wrote:
| Quote: | Bob, Nope, a Rotax is a geared engine and when
the engine stops so does the prop. Even the two
strokes with relatively low compression compared
to the 10.5 to 1 of the 912S series engines
bring the prop to a stop PDQ when the engine stops running.Â
Learned this the hard way when the engine on my
Kolb quit on a downwind departure. Fortunately I
was able to glide back to the runway and miss
the idiot in the Baron who was taking off
downwind so it ended well. Some new Hanes and a
fuel filter and I was good as new.
Rick Girard
|
Shucks . . . I knew that. Thanks for the
refresher course!
Bob . . .
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