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  #1  
Old 04-17-2012, 09:19 AM
Dvalcik's Avatar
Dvalcik Dvalcik is offline
 
Join Date: Jul 2011
Location: Royersford, PA
Posts: 883
Default External Alternator for the Rotax

Adding the External Alternator has been an interesting modification for my RV12 - EAB. With all of the avionics I needed the extra power. After inspecting where the alternator would go, it was identified modifications to the mounting bracket, hose placement, cowling, and cooling shroud would need to be done. Basically the alternator sits on the pilot side and conflicts with the left intake for the scat hose to the cooling shroud .

Started the mods over the last few weekends,
1. Design a modification for the existing alternator bracket. Allowing for clearance with the upper cowl. The bracket is being finalized; we worked by tacking first for placement. I hope to every all install this weekend
2. Prop extension for the 3 blade Sensenich
3. The cowl is approximately ? in longer
4. Modify the cooling Shroud - Relocated the 90 degree intake off the shroud to the left side.
5. Modify the Cowl - Intake mod, cut off the inter lip on the lower cowl and moved it to the left intake.

These pictures are a few days old and are of the ruff fiberglass work. The nice thing is the left side intake will help keep the alternator cool.

I will post more pictures of the finished project once done. I need to thank the guys at KPTW; Al, Ned, Mark, Scott, Dick for their suggestions / help and Bill for fabricating of the mounting brackets



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David
EAA 1250 KPTW
Royersford, PA
david@rv12pilot.com
2021 VAF Supporter


RV12 #568 EAB
* Started 9/30/2011
* 1st flight 8/30/12


http://www.rv12pilot.com
https://www.youtube.com/user/dvalcik
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  #2  
Old 04-17-2012, 12:20 PM
Andy J Andy J is offline
 
Join Date: Mar 2007
Location: Minden, NV
Posts: 145
Default

Hi David,
Interesting.

I'm good with mine the way it is(No ext Alt), but have heard others desire for more juice.

Do you have a prediction for the effect on W&B?
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RV-12: Oshkosh 2012 "Outstanding Workmanship"
RV-6: Bought Flying - "She's a good ole bird"
-PAID 2014-
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  #3  
Old 04-17-2012, 12:41 PM
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Dvalcik Dvalcik is offline
 
Join Date: Jul 2011
Location: Royersford, PA
Posts: 883
Default Andy

Not sure on the W&B, I hope to have her on the scales in about 45 days after paint. Sensenich states the 3 blade wt is less then the 2 blade, but the small increase in weight for the alternator will have an effect, just how much???

I need the power for my panel design

2 GRT's Garmin 796, sl30, 327 and a Navworx ADS-b

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David
EAA 1250 KPTW
Royersford, PA
david@rv12pilot.com
2021 VAF Supporter


RV12 #568 EAB
* Started 9/30/2011
* 1st flight 8/30/12


http://www.rv12pilot.com
https://www.youtube.com/user/dvalcik
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  #4  
Old 04-17-2012, 04:09 PM
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Bill_H Bill_H is offline
 
Join Date: Aug 2010
Location: Marshall TX (KASL)
Posts: 1,793
Default

This is going to be a great thread!

Did you consider an external alternator driven from the accessory pad on the back of the gearbox? Like this 20amp $700 example?
http://www.aircraftspruce.com/catalo...alternator.php
(I have NO IDEA if it would actually "fit" given the other stuff on the top of the engine.)


++++++++++++++++
For reference purposes:
Regarding the new Rotax fuel-injected engine electrical system - this is from the ROTAX manual on it.

QUOTE
Two alternators are built into the stator.
Alternator A is only used for electronic engine components (ignition, injection, and sensors).
Alternator B is used primarily to start the engine and charge the aircraft battery.

While the engine is running, Alternator B can be used for the on-board instruments.
Alternator A 14V/16A (220 watts nominal)
Alternator B 14V/30A (420 watts nominal)
If Alternator A fails, Alternator B takes over its functions. This means that the bettery will no longer be charged and no voltage will be available for the on-board instruments.
UNQUOTE

Besides these an optional external alternator is also available:
"600 watts DC at 6000 rpm"
"14.2 V to 14.8 V"
"6.61 lbs"
It appears to be about 40 amps at 4000 engine rpm.

Note that the engine has TWO electric-driven fuel pumps.
These are listed as "optional" and are listed as 10 amps each (in one place) but 10 amps total (in another place). Confusing.
And, they supply at 65 psi. This optional assembly is recommended to be installed under the fuel tank, with an upstream filter and water trap.
+++++++++++++++++++
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  #5  
Old 04-17-2012, 04:50 PM
Dvalcik's Avatar
Dvalcik Dvalcik is offline
 
Join Date: Jul 2011
Location: Royersford, PA
Posts: 883
Default Bill

I already had the Rotax 912 and removed it from my old SportHornet ELSA. The Rotax has 135 hours and had the external Alternator. I did look into the one you asked about, but more investment and the one I have is turning out to be a good solution with the mods.

We are talking to Rotax regarding which direction to hook up the two alternators. The original setup had both charging with switch circuit breakers on each. Still researching!

Open for suggestions?
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David
EAA 1250 KPTW
Royersford, PA
david@rv12pilot.com
2021 VAF Supporter


RV12 #568 EAB
* Started 9/30/2011
* 1st flight 8/30/12


http://www.rv12pilot.com
https://www.youtube.com/user/dvalcik
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  #6  
Old 04-17-2012, 10:13 PM
splitty splitty is offline
 
Join Date: Dec 2007
Location: Hervey Bay Queensland Australia
Posts: 205
Wink spare Alternator

[quote=Bill_H;650880]This is going to be a great thread!

Did you consider an external alternator driven from the accessory pad on the back of the gearbox? Like this 20amp $700 example?
http://www.aircraftspruce.com/catalo...alternator.php
(I have NO IDEA if it would actually "fit" given the other stuff on the top of the engine.)


++++++++++++++++
For reference purposes:
Regarding the new Rotax fuel-injected engine electrical system - this is from the ROTAX manual on it.

QUOTE
Two alternators are built into the stator.
Alternator A is only used for electronic engine components (ignition, injection, and sensors).
Alternator B is used primarily to start the engine and charge the aircraft battery.

While the engine is running, Alternator B can be used for the on-board instruments.
Alternator A 14V/16A (220 watts nominal)
Alternator B 14V/30A (420 watts nominal)
If Alternator A fails, Alternator B takes over its functions. This means that the bettery will no longer be charged and no voltage will be available for the on-board instruments.
UNQUOTE

Besides these an optional external alternator is also available:
"600 watts DC at 6000 rpm"
"14.2 V to 14.8 V"
"6.61 lbs"
It appears to be about 40 amps at 4000 engine rpm.

Note that the engine has TWO electric-driven fuel pumps.
These are listed as "optional" and are listed as 10 amps each (in one place) but 10 amps total (in another place). Confusing.
And, they supply at 65 psi. This optional assembly is recommended to be installed under the fuel tank, with an upstream filter and water trap.
+++++++++++++++++++[/QUOTE
Somewhere in this forum on MUCH earlier postings there is a picture of a Rotax 912 with an Alternator fitted to the accessory pad .... do a search to find it!
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  #7  
Old 04-23-2012, 09:18 AM
Dvalcik's Avatar
Dvalcik Dvalcik is offline
 
Join Date: Jul 2011
Location: Royersford, PA
Posts: 883
Default Update on the progress

A few new pictures from this weekend. Tried the bracket for fit and final welding.


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David
EAA 1250 KPTW
Royersford, PA
david@rv12pilot.com
2021 VAF Supporter


RV12 #568 EAB
* Started 9/30/2011
* 1st flight 8/30/12


http://www.rv12pilot.com
https://www.youtube.com/user/dvalcik
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  #8  
Old 02-16-2013, 11:26 PM
Cirrus Man Cirrus Man is offline
 
Join Date: Feb 2013
Location: Carlsbad, CA
Posts: 30
Smile Additional Power for Electroincs & Lighting

Any recent updates on how to get more power to run additional electronics, and lighting.
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  #9  
Old 02-17-2013, 09:34 AM
bhassel's Avatar
bhassel bhassel is offline
 
Join Date: Jan 2005
Posts: 979
Default

[quote=splitty;651010]
Quote:
Originally Posted by Bill_H View Post
This is going to be a great thread!

Did you consider an external alternator driven from the accessory pad on the back of the gearbox? Like this 20amp $700 example?
http://www.aircraftspruce.com/catalo...alternator.php
(I have NO IDEA if it would actually "fit" given the other stuff on the top of the engine.)
...

Somewhere in this forum on MUCH earlier postings there is a picture of a Rotax 912 with an Alternator fitted to the accessory pad .... do a search to find it!
I've able to find two threads on this and not much detail. I'd love it if there was something else I'm missing...

http://www.vansairforce.com/communit...ad.php?t=80077
http://www.vansairforce.com/communit...ight=altenator

Bob
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  #10  
Old 02-17-2013, 12:33 PM
E. D. Eliot E. D. Eliot is offline
 
Join Date: Dec 2005
Location: San Pedro
Posts: 1,017
Default Looks Good

David - looks good to me - should eliminate any concern about 'brown outs', etc. I'll be following your work on this and hope that it is all that you hope for. Will you isolate the power from this alt. or will you tie it directly into the main power buss? Please continue to post on this most interesting modification. Do you know how many hp this alternator will use?
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