Question for 'airplane gearheads'......

[Phu Cat]

....regarding fuel pickup.

I'm guessing the fuel pickup in any fuel tank in an airplane is at the bottom. However, when a plane goes inverted, what was now the bottom of the fuel tank becomes the top and the fuel naturally drains away from the pickup. How do the designers keep the engines supplied with fuel while they're upside down?

PC

[rhino 2]

....regarding fuel pickup.

I'm guessing the fuel pickup in any fuel tank in an airplane is at the bottom. However, when a plane goes inverted, what was now the bottom of the fuel tank becomes the top and the fuel naturally drains away from the pickup. How do the designers keep the engines supplied with fuel while they're upside down?

PC

They use a flop hose (pickup hose with a Weight on the end ) in the tank ..

[cScjhb]

A thought provoking question and answer. I looked up what fighter jets do to maintain fuel flow during their maneuvers. Quite an elaborate system of check valves, booster pumps and pressurized stuff. I have been inside dozens and dozens of jet fuel tanks (737s & 747s) but never gave a thought about fuel delivery systems. Interesting..... Jim

[Sully]

The Tanks Are Under constant Pressure Forcing the Fuel To Flow..........

[vwbug72501]

A thought provoking question and answer. I looked up what fighter jets do to maintain fuel flow during their maneuvers. Quite an elaborate system of check valves, booster pumps and pressurized stuff. I have been inside dozens and dozens of jet fuel tanks (737s & 747s) but never gave a thought about fuel delivery systems. Interesting..... Jim

Raises an interesting question: Why and how often would one want to fly a 737 or 747 inverted???

[Phu Cat]

Well VW, in thinking about my original question, guess I should have mentioned I was referring to fighters. My mistake.

PC

[cScjhb]

Raises an interesting question: Why and how often would one want to fly a 737 or 747 inverted???

It's been done. Well, not on purpose EXCEPT Tex Johnston, Boeing test pilot, did 2 barrel rolls in a 707 prototype over Lake Washington during Seattle's annual Seafair celebration. It was in the mid-1950s. I was there to see it..... Jim

[Phu Cat]

I have been inside dozens and dozens of jet fuel tanks



Really interesting statement cScjhb. Are those tanks big enough to stand up in? What was the purpose of going inside? How are they ventilated and dried before you were allowed to get inside?

I used to work for a chemical company (2010) that had a STRICT rule about entering enclosed spaces and ventilating them while you're inside. But I'll bet your experience came before these types of rules were in place.

PC

[cScjhb]

I have been inside dozens and dozens of jet fuel tanks



Really interesting statement cScjhb. Are those tanks big enough to stand up in? What was the purpose of going inside? How are they ventilated and dried before you were allowed to get inside?

I used to work for a chemical company (2010) that had a STRICT rule about entering enclosed spaces and ventilating them while you're inside. But I'll bet your experience came before these types of rules were in place.

PC

I worked for Boeing for a few years as a Quality Control Inspector. One of my assignments was on the wing line for the first 737s. Crawled all over inside the wing tanks inspecting stuff. These were new wings being manufactured. There were thick foam rubber pads in the tanks to crawl on once the skins were attached to the spars. We just had fans blowing air into the tanks for ventilation.

One of my very best assignments was when I was on graveyard shift. There was one crew of 6 or 8 guys and their supervisor. I was assigned to inspect their work. They would do a specific "job", then I would do the required inspection before they could proceed to the next phase and so on. Sometimes there could be an hour or two between inspections. I just let the crew know which wing I was in, and I crawled up inside and....zzzzzzzz'd out. Fun job!

Next time you're flying in an early model 737 think about a sleepy headed 19 or 20 year old who was one of the people to make sure the wings were put together correctly..... Jim

[Rmitchell55]

I see the MV-22 Osprey's flying over my house all the time. Most of the time the engines are vertical or just a few degrees forward. I have seen they fly with the engines horizontal. The same question not with fuel this time but oil pressure.

[easybiker2u]

....regarding fuel pickup.

I'm guessing the fuel pickup in any fuel tank in an airplane is at the bottom. However, when a plane goes inverted, what was now the bottom of the fuel tank becomes the top and the fuel naturally drains away from the pickup. How do the designers keep the engines supplied with fuel while they're upside down?

PC

Aircraft that are certified for aerobatic flight have fuel pumps and check valves for inverted flight. Non aerobatic aircraft do not. You can roll any aircraft and maintain power as long as you keep positive G's on the aircraft, but you cannot maintain inverted flight for an extended period unless it is certified aerobatic.

[Phu Cat]

Thanks Easybiker, that clears things up.

PC

[wehrme]

I wonder if my trike has inverted fuel pickups? I'd hate to be upside down and have the engine quit from fuel starvation.

[rhino 2]

I wonder if my trike has inverted fuel pickups? I'd hate to be upside down and have the engine quit from fuel starvation.

Not to worry...The Tip-Over Switch will turn off the engine before that happens....