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  #101  
Old 04-22-2021, 02:52 PM
NinerBikes NinerBikes is online now
 
Join Date: Dec 2018
Location: Granada Hills
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Quote:
Originally Posted by Piper J3 View Post
Job is continuing... Today I wrapped right carb fuel line and output line from mechanical pump. Everything FWF is going to have two wraps of foil-backed fiberglass insulation including return line to tank and fuel pressure hose. I may even insulate side of oil tank nearest the right carburetor. For now, mechanical pump will remain uninsulated – pump is near cowling front air inlet.

First photo shows single wrap of insulation and second photo shows completion with both wraps applied.
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It will be interesting to note your results...

I assume you've retained some prime winter grade Mogas purchased from the local Costco sometime during the winter months?
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  #102  
Old 04-22-2021, 05:20 PM
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greghughespdx greghughespdx is offline
 
Join Date: Nov 2011
Location: Aurora, OR
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Originally Posted by NinerBikes View Post
It will be interesting to note your results...

I assume you've retained some prime winter grade Mogas purchased from the local Costco sometime during the winter months?
(I'm gonna sound a little preachy here...)

Don't. At least not for flying. Using that fuel - even with the added insulation in the photos - would be a big, big mistake in warmer/hot weather. Wintertime auto fuel that is blended for cold winter air has a vapor pressure high enough to cause it to boil/gas off even in higher ambient temperatures, potentially such as when sitting in a gas tank on a hot day exposed to the sun, etc. The solution for high vapor pressure fuels that boil/vapor lock when hot is to change to a fuel that is safe in the environment in which you are operating.

Use fuel intended for the current climate. If your fuel is not appropriate to the environment, drain it and replace it. Put it in your lawn mower and burn it there. Don't ever (read: EVER) use fuel blended for cold weather in hot ambient environments in an airplane. You're just playing with/tempting fate if you do. It's basic physics.

Also, opening the oil door upon shut down helps to limit heat soaking of the engine.

And, I'll point out that the following cautions and warnings appear in the RV-12 POH:

NOTE
To prevent vapor building in the carburetor after shutdown on hot days, the oil door should be left open to let heat out of the cowl. Leaving the canopy in the open position latched with the F-1231G Canopy Catch, will reduce the risk of vapor-lock. (pg. 4-15)

and

CAUTION
Use of poor quality fuel or winter blend fuels in hot conditions may result in vapor lock. (pg. 8-3)

and

WARNING
During high ambient temperature conditions, run the fuel pump for 5 mins to flush the fuel lines and minimize the potential for vapor lock (pg. 4-2)


Stay safe. We publish these items because they are important operational parameters to follow to help ensure the safe operation of the aircraft.
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Van's web site | Instagram | Facebook
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Building RV-8A since Sept 2014
Dual AFS 5600, Avidyne IFD 440, Whirlwind 74RV, Superior XP IO-360
VAF build thread - Flickr photo album - Project Facebook page
Aurora, OR (EAA Chapter 105)

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  #103  
Old 04-22-2021, 06:00 PM
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Piper J3 Piper J3 is offline
 
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I’m going to sound a little anal here… My intention is to reduce the chance of Vapor Lock regardless of fuel used or ambient conditions. I will insulate fuel components FWF to reduce risk of heat soak. I will also monitor Fuel Pressure and Fuel Flow during take-off phase of flight going forward. I am adding temp sensing for under-cowl and fuel line where it T’s to both carburetors. Also installing the higher pressure (4.5-6 psig) FAC-40135 Facet Fuel Pump per Van’s Notification 18-07-12. Regardless of flying season, ground ops will be minimized. No more repeated landings to full stop with taxi back. Instead, landings will be practiced with touch/go to maintain cooling. Oil door has been, and will continue to be, opened with engine stop. I may add a cooling fan at the open oil door to extract heat.

I had a problem with Vapor Lock that I don’t want to experience again. I am not 100% certain that using the “correct” selection of fuel blend will guarantee no Vapor Lock under the severe conditions that aircraft engines are asked to perform.
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 650

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #104  
Old 04-22-2021, 06:14 PM
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greghughespdx greghughespdx is offline
 
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Location: Aurora, OR
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Quote:
Originally Posted by Piper J3 View Post
I’m going to sound a little anal here… My intention is to reduce the chance of Vapor Lock regardless of fuel used or ambient conditions. I will insulate fuel components FWF to reduce risk of heat soak. I will also monitor Fuel Pressure and Fuel Flow during take-off phase of flight going forward. I am adding temp sensing for under-cowl and fuel line where it T’s to both carburetors. Also installing the higher pressure (4.5-6 psig) FAC-40135 Facet Fuel Pump per Van’s Notification 18-07-12. Regardless of flying season, ground ops will be minimized. No more repeated landings to full stop with taxi back. Instead, landings will be practiced with touch/go to maintain cooling. Oil door has been, and will continue to be, opened with engine stop. I may add a cooling fan at the open oil door to extract heat.

I had a problem with Vapor Lock that I don’t want to experience again. I am not 100% certain that using the “correct” selection of fuel blend will guarantee no Vapor Lock under the severe conditions that aircraft engines are asked to perform.
I hear ya, and understand your approach to further mitigate. My reaction was specifically to the idea of retaining/using cold weather fuel, even for test purposes, in a hot weather environment (or, more specifically in any environment other than the cold weather). That sort of testing should be reserved for a safe and open (read: not an airport ... more open and safe than that) test location and executed by someone with enough experience to handle expected and unexpected emergencies.
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Greg Hughes - Van's Aircraft - Director - Community, Media, Marketing, Support
Van's web site | Instagram | Facebook
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Building RV-8A since Sept 2014
Dual AFS 5600, Avidyne IFD 440, Whirlwind 74RV, Superior XP IO-360
VAF build thread - Flickr photo album - Project Facebook page
Aurora, OR (EAA Chapter 105)


Last edited by greghughespdx : 04-22-2021 at 10:06 PM.
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  #105  
Old 04-22-2021, 08:27 PM
rv9builder rv9builder is offline
 
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A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!
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  #106  
Old 04-22-2021, 08:32 PM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
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Originally Posted by rv9builder View Post
A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!
Much less likely to experience vapor lock because the fuel pressure is so much higher.
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  #107  
Old 04-23-2021, 09:30 AM
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rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: North Brunswick, NJ
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Quote:
Originally Posted by rv9builder View Post
A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!
As John said, higher fuel pressure helps prevent vaporization.. and the fuel is constantly circulated from the tank, through the pumps, to the engine.. and whatever is not used by the engine (which is most of it), is returned back to the tank.
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  #108  
Old 04-23-2021, 12:05 PM
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greghughespdx greghughespdx is offline
 
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Originally Posted by rcarsey View Post
As John said, higher fuel pressure helps prevent vaporization.. and the fuel is constantly circulated from the tank, through the pumps, to the engine.. and whatever is not used by the engine (which is most of it), is returned back to the tank.
Unless and until the fuel is boiling/vaporizing before it has a chance to reach and be pressurized at the pump, of course. Very cold weather fuel in a hot fuel tank could also be a problem before the pump gets involved. Just pointing out the multiple parts of the system to think about here.
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Greg Hughes - Van's Aircraft - Director - Community, Media, Marketing, Support
Van's web site | Instagram | Facebook
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Building RV-8A since Sept 2014
Dual AFS 5600, Avidyne IFD 440, Whirlwind 74RV, Superior XP IO-360
VAF build thread - Flickr photo album - Project Facebook page
Aurora, OR (EAA Chapter 105)

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  #109  
Old 04-23-2021, 12:28 PM
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Piper J3 Piper J3 is offline
 
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I finished installing foil-backed fiberglass insulation on fuel lines. Each line has two wraps. I decided to hold up on return-to-tank and fuel pressure lines for now.

I will flight test and start recording data over the weekend...
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 650

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #110  
Old 04-23-2021, 12:35 PM
seagull seagull is offline
 
Join Date: Dec 2019
Location: San Bernardino
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Quote:
Originally Posted by greghughespdx View Post
Unless and until the fuel is boiling/vaporizing before it has a chance to reach and be pressurized at the pump, of course.
The only point the fuel is not under pressure is in the tank. The head pressure in the tank pressurizes it the short distance to the electric pump which pressurizes it to the mechanical pump. Am I missing something?
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