[NA-ish] Probably a stupid question, but...

[ArrowFlyer86]

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NEW STUPID QUESTION!!!

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How come some transponders/ADS-B seem to move in 100' increments, while others have different resolution?
I notice this on my own GTX335. If I leave the pressure altitude display up, it'll normally show nearest 100' increment, but occasionally it will show the nearest 10' or 50'. But I can't find a rhyme or reason for why it all the sudden boosts resolution? Seems to just do it on its own? Or is there some external signal interrogating it telling it to deliver more? I have no idea.

Here's an example. Most most targets are showing up on FF with 25' increments, but the red circled one coming out of KDKB is showing 1577'.

 

[Pinecone]

You know, I've heard that quoted many times but not sure how much data is really behind it. I almost put it in the realm of automotive folklore. The fuel pumps that are cooled that way are typically at the bottom of the fuel sump and would be submerged with a gallon or two of fuel in the tank. Many of the fuel pumps don't sit in the fuel at all unless you've got a full tank as the motor itself is the top and uses a pickup tube to draw from the bottom of the tank.

Example of modern fuel pump on F-150:

We did a straw pole on one of the BMW forums a number of years ago.

No one who refueled at 1/4 most times had to replace a fuel pump. NONE. Of those who refueled at the low fuel light, a reasonable percentage (don't remember the number, but it was not trivial) had to replace a fuel pump or two.

It may be the design of the BMW fuel pumps at the time, but the numbers were telling.

 

[AV8R_87]

Hmm, mine had a very accurate fuel gauge. You could go into the diagnostic menu and it would display fuel quantity in 0.1 liter increments. 99% of the time I was way below 1/4 tank whrn refueling, and I pulled into a gas station indicating 0.0 a few times.
The fuel pump was still running at 250k miles when I replaced that car.

In a plane, on the other hand, you'll almost never catch me landing with less than 1/4 tank.

 

[Salty]

It's a conspiracy. They are slowing gas pumps down more and more each year so we don't complain about how long it takes to charge electric cars.

 

[Dana]

1) With many vehicles, it is better to refuel at 1/4 to avoid issues with the in tank fuel pump over heating.

You know, I've heard that quoted many times but not sure how much data is really behind it. I almost put it in the realm of automotive folklore.

Refueling at 1/4 tank is a good way to make sure you don't run out of gas... and it is true that running out of gas can make an electric fuel pump fail from overheating, at least on some cars (including a Fiero I once owned).

You haven't lived until you've dropped and reinstalled the fuel tank on a Fiero on a gravel driveway...

 

[SoonerAviator]

Refueling at 1/4 tank is a good way to make sure you don't run out of gas... and it is true that running out of gas can make an electric fuel pump fail from overheating, at least on some cars (including a Fiero I once owned).

You haven't lived until you've dropped and reinstalled the fuel tank on a Fiero on a gravel driveway...

I understand that running out of fuel repeatedly can be damaging/overheat an in-tank fuel pump. I'm just saying waiting until you've only got a few gallons left (call it 1/8 tank) when the DTE estimate is barking about "30 Miles to E" isn't likely going to cause any harm. I've never run myself out of fuel needing rescue, so I can't speak to needing a mechanism to avoid it. I did come close with an '88 300ZX, but that's because the fuel gauge wasn't accurate and I knew it was on fumes while it died pulling up to the fuel pump, lol.

 

[Racerx]

######################

NEW STUPID QUESTION!!!

#######################

How come some transponders/ADS-B seem to move in 100' increments, while others have different resolution?
I notice this on my own GTX335. If I leave the pressure altitude display up, it'll normally show nearest 100' increment, but occasionally it will show the nearest 10' or 50'. But I can't find a rhyme or reason for why it all the sudden boosts resolution? Seems to just do it on its own? Or is there some external signal interrogating it telling it to deliver more? I have no idea.

Here's an example. Most most targets are showing up on FF with 25' increments, but the red circled one coming out of KDKB is showing 1577'.
View attachment 140709

I got nothing but a new excuse why Im not holding altitude as well as some. Transponder is on the fine setting.

 

[Dana]

I understand that running out of fuel repeatedly can be damaging/overheat an in-tank fuel pump.

Didn't say anything about repeatedly. On some vehicles (like my Fiero) it only takes running dry once.

 

[Pinecone]

Some in tank fuel pumps the pump is at the bottom (BMW), so the pump is normally cooled by fuel flowing through it and the surrounding fuel in the tank. Run near empty and the pump is no long submerged in fuel for the extra cooling.

It seems that some pumps are at the top of the tank, so this would not apply.

 

[Flatiowa]

You haven't lived until you've dropped and reinstalled the fuel tank on a Fiero on a gravel driveway...

I see you and raise one fiero catching on fire. Dry windy iowa fall day with miles of dry corn in every direction and full tank of gas, narrow gravel road and smoke started rolling out all the dash vents. I knew a mile and half ahead was a picked and worked field so I floored it, window down and looking like a dog with my head out the window, I made it and a couple hundred feet into the field when it started having a steady stream of melting/flaming plastic running out of the dash onto the passenger side floor and I bailed. Within minutes it was fully engulfed, ended up melting the wheels and most of the space frame. I do mis that car though, it was sporty.