Today's Message Index:
----------------------
1. 12:27 PM - 912ULS starts missing at cruise power (Jason Omelchuck)
2. 02:22 PM - Re: 912ULS starts missing at cruise power (FLYaDIVE)
3. 02:54 PM - Re: 912ULS starts missing at cruise power (Bob Harrison)
4. 03:10 PM - Re: 912ULS starts missing at cruise power (FLYaDIVE)
5. 03:14 PM - Re: 912ULS starts missing at cruise power (Jason Omelchuck)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | 912ULS starts missing at cruise power |
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
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@trek-tech.com>wrote:
> jason@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
>
>
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | 912ULS starts missing at cruise power |
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@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
Sent: 24 April 2012 22:22
Subject: Re: RotaxEngines-List: 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@trek-tech.com>
wrote:
<jason@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
==========
-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
==========
http://forums.matronics.com
==========
le, List Admin.
="_blank">http://www.matronics.com/contribution
==========
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 912ULS starts missing at cruise power |
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@talktalk.net> wrote:
> 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@matronics.com [mailto:
> owner-rotaxengines-list-server@matronics.com] *On Behalf Of *FLYaDIVE
> *Sent:* 24 April 2012 22:22
> *To:* rotaxengines-list@matronics.com
> *Subject:* Re: RotaxEngines-List: 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@trek-tech.com>
> wrote:****
>
> jason@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
>
>
> ==========
> -List" target="_blank">
> http://www.matronics.com/Navigator?RotaxEngines-List
> ==========
> http://forums.matronics.com
> ==========
> le, List Admin.
> ="_blank">http://www.matronics.com/contribution
> ==========
>
>
> ****
>
> ** **
>
> * *
>
> * *
>
> **
>
> **
>
> **
>
> **
>
> **
>
> *http://www.matronics.com/Navigator?RotaxEngines-List*
>
> **
>
> **
>
> *http://forums.matronics.com*
>
> **
>
> **
>
> **
>
> **
>
> *http://www.matronics.com/contribution*
>
> **
>
> * *
>
> *
>
> *
>
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | 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
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|