Van's Air Force
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Dual flop tubes
- Thread starter Straun
- Start date
Russ McCutcheon
Well Known Member
Dual flop tubes, you will never go inverted on the wrong tank, I see no down side!
I have investigated at least one accident where the flop tube got hung up and did not supply fuel to the engine.
I'm not saying that this will happen to you. It's just one data point.
704CH
Well Known Member
I put in a flop tube in the left and a standard pick up in the right. Not for any paticular reason except I wanted to see what a flop tube looked like and how it was mounted. Also down the road if I want inverted oil, I have the flop tube already installed.
Flop tubes are much easier to install if you choose capacitive senders. No relocation of the float type sender is necessary.
I plan on having an andair fuel valve with custom writing indicating Left Tank - Aero ; Right Tank - Norm so I don't have to have any notes on checklist;POH etc.
Also, Flop tubes are Heavier. Also, Flop tubes are only necessary if you plan on sustained inverted flight and have an inverted oil system. Many people do acro with standard pick ups with no problem.
Flop tubes are much easier to install if you choose capacitive senders. No relocation of the float type sender is necessary.
I plan on having an andair fuel valve with custom writing indicating Left Tank - Aero ; Right Tank - Norm so I don't have to have any notes on checklist;POH etc.
Also, Flop tubes are Heavier. Also, Flop tubes are only necessary if you plan on sustained inverted flight and have an inverted oil system. Many people do acro with standard pick ups with no problem.
NeilMcLeod
Active Member
I have dual flop tubes and standard fuel gage senders in the second bay outboard and would do it again. It works fine. I think if one is careful about the installation there shouldn't be any issues with the tubes hanging up.
mototopo
Well Known Member
I have a standard pick up tube in the left tank and a flop tube in the right one. I did so just because I decided for the flop tube once my left tank was already complete... by the way, I think just one aerobatic tank is enough.
Relocating the float fuel sender in the second bay is a no issue.. it took me just 30 minutes of work.
Relocating the float fuel sender in the second bay is a no issue.. it took me just 30 minutes of work.
WillyEyeBall
Well Known Member
dual flop tubes
If you search "flop tube" you'll see there have been several incidents of the tube getting stuck or the fittings coming loose with an AD from Van. I have the typical flop in one tank and the standard in the other tank. I fly out to the acro practice area on the non flop tube tank and switch before acro. Before I start an acro practice session, I mentally go through a check lists while includes switching tanks to the flop tube side. I hate to admit, but at least 4 times in the last two years I've been inverted when the engine sputtered and started rolling down because I was on the wrong tank. The first two times really got my attention, but simply rolling out and the engine comes back, and I switch to the flop tube tank. It's really a non event (at least after the 3rd time). I like the safety factor with a standard tank, and I can't practice acro more than 30 minutes at a time anyway (old man).
Bill McLean
RV-4 Slider
Sky Dancing youtube video
If you search "flop tube" you'll see there have been several incidents of the tube getting stuck or the fittings coming loose with an AD from Van. I have the typical flop in one tank and the standard in the other tank. I fly out to the acro practice area on the non flop tube tank and switch before acro. Before I start an acro practice session, I mentally go through a check lists while includes switching tanks to the flop tube side. I hate to admit, but at least 4 times in the last two years I've been inverted when the engine sputtered and started rolling down because I was on the wrong tank. The first two times really got my attention, but simply rolling out and the engine comes back, and I switch to the flop tube tank. It's really a non event (at least after the 3rd time). I like the safety factor with a standard tank, and I can't practice acro more than 30 minutes at a time anyway (old man).
Bill McLean
RV-4 Slider
Sky Dancing youtube video
BSwayze
Well Known Member
I read at least one documented case where a flop tube had become stiff over time. In other words, it didn't "flop" anymore. If that wasn't bad enough, it had become stiff enough that it didn't flop all the way down in the standard aircraft upright orientation, meaning that the pilot didn't have access to all the fuel in that tank during normal upright flight. That can lead to fuel starvation when you still think you have plenty of fuel. If you install any flop tubes, I would think you would want to check for this on your annual inspection. Maybe someone knows the service life of a flop tube, and how often they need to be replaced. I'm no expert on this. If I can remember where I saw that story, I'll post it here. Maybe someone else can remember seeing it, too. It was a long time ago when I was building my wings and considering this question. I ended up putting two standard pickups in my tanks.
BSwayze
Well Known Member
I found it!
Here's the report I read about a flop tube getting stiff with age and not flopping anymore. Should be an alert to all who have flop tubes. It looks like they should be checked often and replaced every once in a while:
http://www.experimentalaero.com/flop_tube_alert.htm
Here's the report I read about a flop tube getting stiff with age and not flopping anymore. Should be an alert to all who have flop tubes. It looks like they should be checked often and replaced every once in a while:
http://www.experimentalaero.com/flop_tube_alert.htm
