Fuel Clunks
11-07-2007 | 10:59 AM
#27
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From: Kalona,
IA
RE: Fuel Clunks
RTK, that sounds like experience talking 
and I know exactly what you mean! I am absolutely astonished at what i find within some of the more extravagant and very expensive birds when the fuel system is torn down.....yet somehow they get away with it. If it were my stuff, the very next flight would be the last one.
Chad
and I know exactly what you mean! I am absolutely astonished at what i find within some of the more extravagant and very expensive birds when the fuel system is torn down.....yet somehow they get away with it. If it were my stuff, the very next flight would be the last one.Chad
11-07-2007 | 11:00 AM
#28
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From: El Reno, OK
RE: Fuel Clunks
RTK - your comment caused me to consider something I've asked on this forum before, and never received a reply to. Perhaps you'll take a shot, and I'd appreciate it!
WHY do we "believe" that a klunk at the back of the tank will "suck air", believing the theoretical (and physically-impossible) statement that "fuel will slosh to the front of the tank, and the klunk will be exposed" ??
Can someone explain how the fuel mass in a tank forward of the CG will move for a long enough period of time to cause the klunk line (and hence fuel line to the carb) to use up all the fuel in the line?
I would like to understand the physics behind this lore of the hobby....
WHY do we "believe" that a klunk at the back of the tank will "suck air", believing the theoretical (and physically-impossible) statement that "fuel will slosh to the front of the tank, and the klunk will be exposed" ??
Can someone explain how the fuel mass in a tank forward of the CG will move for a long enough period of time to cause the klunk line (and hence fuel line to the carb) to use up all the fuel in the line?
I would like to understand the physics behind this lore of the hobby....
11-07-2007 | 11:29 AM
#29
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From: Left Coast ,
CA
RE: Fuel Clunks
aerobob-- There was a thread here on RCU a long time ago that debated this. Some aerospace guy said that the gas in the tank "tends" to stay in the back on a down line and he had some video to show it. As you mentioned a down line at low throttle setting should not empty the line even if all the fuel went forward.
The example I mentioned happened more than once to me. The knock off tygon went stiff, as in solid, in about 3 months on one of my planes. When the tank was less than half full and you did extended inverted flat spins the engine would die. When I finally decided to look at the tank, the clunk would not move from the back bottom. It would take a while before it died..
The example I mentioned happened more than once to me. The knock off tygon went stiff, as in solid, in about 3 months on one of my planes. When the tank was less than half full and you did extended inverted flat spins the engine would die. When I finally decided to look at the tank, the clunk would not move from the back bottom. It would take a while before it died..
11-07-2007 | 11:40 AM
#30
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From: El Reno, OK
RE: Fuel Clunks
ORIGINAL: RTK
aerobob-- There was a thread here on RCU a long time ago that debated this. Some aerospace guy said that the gas in the tank "tends" to stay in the back on a down line and he had some video to show it. As you mentioned a down line at low throttle setting should not empty the line even if all the fuel went forward.
The example I mentioned happened more than once to me. The knock off tygon went stiff, as in solid, in about 3 months on one of my planes. When the tank was less than half full and you did extended inverted flat spins the engine would die. When I finally decided to look at the tank, the clunk would not move from the back bottom. It would take a while before it died..
aerobob-- There was a thread here on RCU a long time ago that debated this. Some aerospace guy said that the gas in the tank "tends" to stay in the back on a down line and he had some video to show it. As you mentioned a down line at low throttle setting should not empty the line even if all the fuel went forward.
The example I mentioned happened more than once to me. The knock off tygon went stiff, as in solid, in about 3 months on one of my planes. When the tank was less than half full and you did extended inverted flat spins the engine would die. When I finally decided to look at the tank, the clunk would not move from the back bottom. It would take a while before it died..
Thanks again.
11-07-2007 | 11:49 AM
#32
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From: El Reno, OK
RE: Fuel Clunks
Me, too, and your reminder about line flexibility is worth filing away in the memory bank (as long as I can remember where it's filed)
I use a "Tygon" from McMaster Carr that seems to remain flexible, and has "TYGON" plus the spec # printed on it.... seems to have held up properly so far, not getting inflexible.
Do you have a "preferred" source of good Tygon and Neoprene that is 'real' stuff?
I use a "Tygon" from McMaster Carr that seems to remain flexible, and has "TYGON" plus the spec # printed on it.... seems to have held up properly so far, not getting inflexible.
Do you have a "preferred" source of good Tygon and Neoprene that is 'real' stuff?
