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Jason Omelchuck
Joined: 07 May 2009
Posts: 120
Location: Portland Oregon
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 Posted: Tue Apr 24, 2012 11:25 am Post subject: 912ULS starts missing at cruise power |
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I though I might throw this out for the group to ponder. I was out flying yesterday and I had just leveled off at 8500 feet when the engine started to miss. I reduced power (to 5000) and the miss went away. Increase power again and it was back. I pulled the power back and went the long safe way around the mountains instead of over as I had intended. When I got closer to home, I could run the engine at extended high power and no miss. The miss is just like when I discovered some water in the float bowls. My theory is that when I climbed to 8500ft, the temperature was a full 40 degrees less than when I took off and that caused water to condense out of the fuel. When I got close to home, the temperature was 80 degrees and the water went back in solution and the problem went away. I am using premium mo gas with 10 percent ethanol.
Jason
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Tue Apr 24, 2012 1:22 pm Post subject: 912ULS starts missing at cruise power |
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Jason:
Am I to assume that 80F was on the ground and 40 deg colder was at 8500'?
If so that is a 40 Deg change in HOW MANY FEET?
A standard Adiabatic Lapse Rate is 3.5Deg F (2 C) per 1000'.
SO.... a 40 deg F change would have put you at 11,428' and that is starting from sea level.
Did you really see a 40 Deg change?
If you did you could have been at a Pressure Altitude above the ceiling of your engine setup.
How does the Ratax adjust for altitude?
If you were RICH on the ground then without mixture adjustment or insufficient mixture adjustment you were Way Rich at altitude.
Lowering the RPM would reduce the HP and reduce the required accuracy of the Air:Fuel Ratio.
Barry
On Tue, Apr 24, 2012 at 3:25 PM, Jason Omelchuck <jason(at)trek-tech.com (jason(at)trek-tech.com)> wrote:
[quote]--> RotaxEngines-List message posted by: "Jason Omelchuck" <jason(at)trek-tech.com (jason(at)trek-tech.com)>
I though I might throw this out for the group to ponder. I was out flying yesterday and I had just leveled off at 8500 feet when the engine started to miss. I reduced power (to 5000) and the miss went away. Increase power again and it was back. I pulled the power back and went the long safe way around the mountains instead of over as I had intended. When I got closer to home, I could run the engine at extended high power and no miss. The miss is just like when I discovered some water in the float bowls. My theory is that when I climbed to 8500ft, the temperature was a full 40 degrees less than when I took off and that caused water to condense out of the fuel. When I got close to home, the temperature was 80 degrees and the water went back in solution and the problem went away. I am using premium mo gas with 10 percent ethanol.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371723#371723
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ptag.dev(at)talktalk.net
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| Posted: Tue Apr 24, 2012 1:54 pm Post subject: 912ULS starts missing at cruise power |
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Barry /Jason
Pleased Barry has put his submission in because I was going to raise the vaporisation issue at that altitude on Mogas . Probably quite likely since the fuel source in the tank would be at ground ambient before take off so IMHO you were well into Mogas vaporisation range. Then return to lower level it would disappear ! I think 5,000ft at max ambient of 22deg is the understood limit. Perhaps someone of more authoritive knowledge on vaporisation would like to comment further.
Regards
Bob Harrison G-PTAG but with Turbo !
From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of FLYaDIVE
Sent: 24 April 2012 22:22
To: rotaxengines-list(at)matronics.com
Subject: Re: 912ULS starts missing at cruise power
Jason:
Am I to assume that 80F was on the ground and 40 deg colder was at 8500'?
If so that is a 40 Deg change in HOW MANY FEET?
A standard Adiabatic Lapse Rate is 3.5Deg F (2 C) per 1000'.
SO.... a 40 deg F change would have put you at 11,428' and that is starting from sea level.
Did you really see a 40 Deg change?
If you did you could have been at a Pressure Altitude above the ceiling of your engine setup.
How does the Ratax adjust for altitude?
If you were RICH on the ground then without mixture adjustment or insufficient mixture adjustment you were Way Rich at altitude.
Lowering the RPM would reduce the HP and reduce the required accuracy of the Air:Fuel Ratio.
Barry
On Tue, Apr 24, 2012 at 3:25 PM, Jason Omelchuck <jason(at)trek-tech.com (jason(at)trek-tech.com)> wrote:
--> RotaxEngines-List message posted by: "Jason Omelchuck" <jason(at)trek-tech.com (jason(at)trek-tech.com)>
I though I might throw this out for the group to ponder. I was out flying yesterday and I had just leveled off at 8500 feet when the engine started to miss. I reduced power (to 5000) and the miss went away. Increase power again and it was back. I pulled the power back and went the long safe way around the mountains instead of over as I had intended. When I got closer to home, I could run the engine at extended high power and no miss. The miss is just like when I discovered some water in the float bowls. My theory is that when I climbed to 8500ft, the temperature was a full 40 degrees less than when I took off and that caused water to condense out of the fuel. When I got close to home, the temperature was 80 degrees and the water went back in solution and the problem went away. I am using premium mo gas with 10 percent ethanol.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371723#371723
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="_blank">http://www.matronics.com/contribution
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| Quote: | | http://www.matronics.com/Navigator?RotaxEngines-List |
01234567
[quote][b]
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Tue Apr 24, 2012 2:10 pm Post subject: 912ULS starts missing at cruise power |
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Bob:
I doubt if vaporization was the cause. Reasons being:
1 - Temperature of 40F is cold enough to prevent vaporization.
2 - From personal experience - I have taken my plane to 13,500' on MoGas and never experienced any problems.
No, I did not have oxygen. Not required... 
I would be concerned about engine instillation and mixture control.
But what is the posted Max Alt for the engine?
Barry
On Tue, Apr 24, 2012 at 5:53 PM, Bob Harrison <ptag.dev(at)talktalk.net (ptag.dev(at)talktalk.net)> wrote:
[quote]
Barry /Jason
Pleased Barry has put his submission in because I was going to raise the vaporisation issue at that altitude on Mogas . Probably quite likely since the fuel source in the tank would be at ground ambient before take off so IMHO you were well into Mogas vaporisation range. Then return to lower level it would disappear ! I think 5,000ft at max ambient of 22deg is the understood limit. Perhaps someone of more authoritive knowledge on vaporisation would like to comment further.
Regards
Bob Harrison G-PTAG but with Turbo !
From: owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com) [mailto:owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com)] On Behalf Of FLYaDIVE
Sent: 24 April 2012 22:22
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: Re: 912ULS starts missing at cruise power
Jason:
Am I to assume that 80F was on the ground and 40 deg colder was at 8500'?
If so that is a 40 Deg change in HOW MANY FEET?
A standard Adiabatic Lapse Rate is 3.5Deg F (2 C) per 1000'.
SO.... a 40 deg F change would have put you at 11,428' and that is starting from sea level.
Did you really see a 40 Deg change?
If you did you could have been at a Pressure Altitude above the ceiling of your engine setup.
How does the Ratax adjust for altitude?
If you were RICH on the ground then without mixture adjustment or insufficient mixture adjustment you were Way Rich at altitude.
Lowering the RPM would reduce the HP and reduce the required accuracy of the Air:Fuel Ratio.
Barry
On Tue, Apr 24, 2012 at 3:25 PM, Jason Omelchuck <jason(at)trek-tech.com (jason(at)trek-tech.com)> wrote:
--> RotaxEngines-List message posted by: "Jason Omelchuck" <jason(at)trek-tech.com (jason(at)trek-tech.com)>
I though I might throw this out for the group to ponder. I was out flying yesterday and I had just leveled off at 8500 feet when the engine started to miss. I reduced power (to 5000) and the miss went away. Increase power again and it was back. I pulled the power back and went the long safe way around the mountains instead of over as I had intended. When I got closer to home, I could run the engine at extended high power and no miss. The miss is just like when I discovered some water in the float bowls. My theory is that when I climbed to 8500ft, the temperature was a full 40 degrees less than when I took off and that caused water to condense out of the fuel. When I got close to home, the temperature was 80 degrees and the water went back in solution and the problem went away. I am using premium mo gas with 10 percent ethanol.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371723#371723
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le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
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Jason Omelchuck
Joined: 07 May 2009
Posts: 120
Location: Portland Oregon
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| Posted: Tue Apr 24, 2012 2:13 pm Post subject: Re: 912ULS starts missing at cruise power |
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Hello,
Yes, I know it was not a standard lapse rate day, we had record heat here in Portland and there must been some cold air flowing over the top. I have flow at 9500 feet on mo gas on some warm days and never had a problem. But it could be vapor pressure issues. Why would that change with throttle setting? Rotax engines have no mixture control. I am going to check the float bows for water as the symptoms were exactly last time I found water droplets in them. I appreciate the feedback.
Jason
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max8992
Joined: 28 Jul 2011
Posts: 142
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| Posted: Tue Apr 24, 2012 11:51 pm Post subject: 912ULS starts missing at cruise power |
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Hi There All,
MoGas with 10% ethanol... I won't use that type of fuel because of chemical impact on gaskets and filters and plastics and (I heard) vapor condensation possibility which to me looks like the problem you had. And at the end of the day the difference in price with non ethanol MoGas is about 0.05€ per liter or 1€ per hour of flight.
Cheers,
Max Cointe
Europa F-PMLH TriGear Kit #560
912ULS Airmaster 420 hours
mcointe(at)free.fr
-----Message d'origine-----
De : owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] De la part de Jason Omelchuck
Envoyé : mercredi 25 avril 2012 00:14
À : rotaxengines-list(at)matronics.com
Objet : Re: 912ULS starts missing at cruise power
Hello,
Yes, I know it was not a standard lapse rate day, we had record heat here in Portland and there must been some cold air flowing over the top. I have flow at 9500 feet on mo gas on some warm days and never had a problem. But it could be vapor pressure issues. Why would that change with throttle setting? Rotax engines have no mixture control. I am going to check the float bows for water as the symptoms were exactly last time I found water droplets in them. I appreciate the feedback.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371733#371733
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Max8992
Europa XS #560 F-PMLH |
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Wed Apr 25, 2012 3:37 am Post subject: Re: 912ULS starts missing at cruise power |
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It might have been carb ice.
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Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
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KeysFox
Joined: 05 Jan 2009
Posts: 137
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| Posted: Wed Apr 25, 2012 6:42 am Post subject: 912ULS starts missing at cruise power |
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Someone with technical expertise might offer comments on the risk of phase
seperation of ethanol and water from mo gas with a big decrease in temp at
altitude.
When I have experienced phase seperation, the full ten percent (roughly)
of the fuel that is ethanol & water settled to the bottom of the tanks and
the engines would not run on the settleout. So the idea of a little bit of
settleout does not fit my experience.
Love to hear from someone in the fuel science industry.
My prevetive measure is to use ethanol free auto gas from marina's and by
checking puregas.com when traveling to find gas stations with ethanol free
gas.
BJ
Kitfox IV 912
old fiberglass tanks so can not use gasahol
>
| Quote: | <jason(at)trek-tech.com>
I though I might throw this out for the group to ponder. I was out flying
yesterday and I had just leveled off at 8500 feet when the engine started
to miss. I reduced power (to 5000) and the miss went away. Increase
power again and it was back. I pulled the power back and went the long
safe way around the mountains instead of over as I had intended. When I
got closer to home, I could run the engine at extended high power and no
miss. The miss is just like when I discovered some water in the float
bowls. My theory is that when I climbed to 8500ft, the temperature was a
full 40 degrees less than when I took off and that caused water to
condense out of the fuel. When I got close to home, the temperature was
80 degrees and the water went back in solution and the problem went away.
I am using premium mo gas with 10 percent ethanol.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371723#371723
|
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
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_________________
B Jones
N154K
443-480-1023 |
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phactor9
Joined: 16 Jun 2011
Posts: 78
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| Posted: Thu Apr 26, 2012 12:40 pm Post subject: 912ULS starts missing at cruise power |
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You can test for ethanol laden gas (if you should ever doubt the source you bought from) by adding 10% water to a small, tall, thin container of gas, shaking, and watching to see if the 10% mark increases.
If the level of the water (at the bottom) stays the same, you have ethanol-free gas. If it increases to, say, roughly 15%, that means you have 10% alcohol in the gas - I read that in a test like this, only half the ethanol will "disolved down into the water; the other 5% will stay suspended in the gas.
Phil H
FF11-4-00076; still building
CRE mz201 626cc
maiden voyage hopefully the first week of May.
--- On Wed, 4/25/12, bjones(at)dmv.com <bjones(at)dmv.com> wrote:
| Quote: |
From: bjones(at)dmv.com <bjones(at)dmv.com>
Subject: Re: 912ULS starts missing at cruise power
To: rotaxengines-list(at)matronics.com
Date: Wednesday, April 25, 2012, 10:42 AM
--> RotaxEngines-List message posted by: [url=/mc/compose?to=bjones(at)dmv.com]bjones(at)dmv.com[/url]
Someone with technical expertise might offer comments on the risk of phase
seperation of ethanol and water from mo gas with a big decrease in temp at
altitude.
When I have experienced phase seperation, the full ten percent (roughly)
of the fuel that is ethanol & water settled to the bottom of the tanks and
the engines would not run on the settleout. So the idea of a little bit of
settleout does not fit my experience.
Love to hear from someone in the fuel science industry.
My prevetive measure is to use ethanol free auto gas from marina's and by
checking puregas.com when traveling to find gas stations with ethanol free
gas.
BJ
Kitfox IV 912
old fiberglass tanks so can not use gasahol
> --> RotaxEngines-List message posted by: "Jason Omelchuck"
| Quote: | <[url=/mc/compose?to=jason(at)trek-tech.com]jason(at)trek-tech.com[/url]>
I though I might throw this out for the group to ponder. I was out flying
yesterday and I had just leveled off at 8500 feet when the engine started
to miss. I reduced power (to 5000) and the miss went away. Increase
power again and it was back. I pulled the power back and went the long
safe way around the mountains instead of over as I had intended. When I
got closer to home, I could run the engine at extended high power and no
miss. The miss is just like when I discovered some water in the float
bowls. My theory is that when I climbed to 8500ft, the temperature was a
full 40 degrees less than when I took off and that caused water to
condense out of the fuel. When I got close to home, the temperature was
80 degrees and the water went back in solution and the problem went away.
I am using premium mo gas with 10 percent ethanol.
Jason
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371723#371723
http://www.matronics.com/Navigator?RotaxEngines-Lis --> http://www.matronics.c===================
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capedavis(at)yahoo.com
Guest
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| Posted: Thu Apr 26, 2012 1:44 pm Post subject: 912ULS starts missing at cruise power |
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Phil Your building is going well if you are going to fly the first week of may! Good luck hope that 201 is a smooth strong runner
Chris Davis
KXP 503 492 hrs
Glider Pilot
Disabled from crash building Firefly
From: Phil <phactor9(at)yahoo.com>
To: rotaxengines-list(at)matronics.com
Sent: Thursday, April 26, 2012 4:37 PM
Subject: Re: RotaxEngines-List: 912ULS starts missing at cruise power
You can test for ethanol laden gas (if you should ever doubt the source you bought from) by adding 10% water to a small, tall, thin container of gas, shaking, and watching to see if the 10% mark increases.
If the level of the water (at the bottom) stays the same, you have ethanol-free gas. If it increases to, say, roughly 15%, that means you have 10% alcohol in the gas - I read that in a test like this, only half the ethanol will "disolved down into the water; the other 5% will stay suspended in the gas.
Phil H
FF11-4-00076; still building
CRE mz201 626cc
maiden voyage hopefully the first week of May.
--- On Wed, 4/25/12, bjones(at)dmv.com <bjones(at)dmv.com> wrote:
| Quote: |
From: bjones(at)dmv.com <bjones(at)dmv.com>
Subject: Re: 912ULS starts missing at cruise power
To: rotaxengines-list(at)matronics.com
Date: Wednesday, April 25, 2012, 10:42 AM
--> RotaxEngines-List message posted by: puregas.com when traveling to find gas stations with ethanol freegas.BJKitfox IV 912old fiberglass tanks so can not use gasahol> --> RotaxEngines-List message posted by: "Jason Omelchuck"> <jason(at)trek-tech.com>>> I though I might throw this out for the group to ponder. I was out flying> yesterday and I had just leveled off at 8500 feet when the engine started> to miss. I reduced power (to 5000) and the miss went away. Increase> power again and it was back. I pulled the power back and went the long> safe way around the mountains instead of over as I had intended. When I> got closer to home, I could run the engine at extended high power and no> miss. The miss is just like when I discovered some water in the float> bowls. My theory is that when I climbed to 8500ft, the temperature was a> full 40 degrees less than when I took off and that caused water to> condense out of the fuel. When I got close to home, the temperature was> 80 degrees and the water went back in solution and the problem went away.> I am using premium mo gas with 10 percent ethanol.>> Jason>>>>> Read this topic online here:>> http://forums.matronics.com/viewtopic.php?p=371723#371723>>>>>>> http://www.matronics.com/Navigator?RotaxEngines-Lis --> http://www.matronics.c===================
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