Fuel starvation in a slip

flyinga · #1 09-09-2012, 12:24 PM

I've searched the forums and haven't been able to find an answer to my question: What is the minimum tank fuel you can have during a hard slip that will not cause possible fuel starvation? Have any of you done this scientifically or am I going to have to do it myself?

I was in a hard base to final slip with 5-10 gallons remaining in the low wing and got a "low fuel" warning on the Dynon and the gage for that tank showed 1 gallon ramaning. I stopped the slip so it was a non-issue.

Thanks,

airguy · #2 09-09-2012, 12:28 PM

That's going to depend greatly on exactly how the pickup tube is placed in the wing and how the holes are cut in the dip tube, so the answer really is "it depends". Even flop tubes may not land in exactly the same place each time.

flyinga · #3 09-09-2012, 01:06 PM

Greg, You are of course correct about aifcraft variations. I guess I was just looking for the easy way out. Guess I'll have to do some experimenting.
Thanks,

Andy Hill · #4 09-09-2012, 01:06 PM

Quote:

I've searched the forums and haven't been able to find an answer to my question: What is the minimum tank fuel you can have during a hard slip that will not cause possible fuel starvation? Have any of you done this scientifically or am I going to have to do it myself?

Why do something of such questionable benefit / airmanship?

Just select the "high" tank frst

PS And I speak from experience having learnt that lesson the hard way, as did those below treated to a few nice backfires

gasman · #5 09-09-2012, 01:55 PM

I would complete my standard rate turn base to final before I started my slip. Then if a slip is needed, and you have a carb, just go for it. You won't be in the slip more that a few seconds, and your throttle is closed at this time = low fuel burn, and you did turn on the fuel pump before entering downwind. Remember, you are only a few hundred feet above the ground with more altitude than you need to make the runway.

Test it. Go to 3-4K agl with 3 gallons in the lower tank. Slow down to approach speed, flaps, fuel pump on and throttle closed. Slip it for a thousand feet, see how long it takes and see if the fuel supply fails.

flyinga · #6 09-09-2012, 01:58 PM

A matter of curiosity. With fuel tanks equal at some point it may be nice to know that a slip (an airmanship tool in my opinion) is ill advised.

WAM120RV · #7 09-09-2012, 02:02 PM

One of our group members did something like this a couple of weeks ago.

Slipped to the left on a low left tank, then did not understand why the engine would pick up when he applied more throttle. Then when he came out of the slip the engine picked up. He had decided he had enough height and speed to glide in then (so obviously he did not need the extra powere when he called for it)ank

So, the next thing he did was killed the engine rather than just pulling back the throttle........ so he left himself with no options at all..... he was now a glider.

Thankfully he pulled off the landing, then restarted the engine and taxied in.

Now!!! all of this could have been avoided by a bit of good airmanship. Simply by selecting the wing high tank before slipping and there is no problem..... so why deliberately try to cause one?

Our man now understands the need to select the higher fuel tank, but does not seem to comprehend the potential problem he caused by killing the engine rather than just closing the throttle????

airguy · #8 09-09-2012, 02:30 PM

Another good reason to have electric fuel pumps in each wing root, rather than the engine-driven fuel pump. Simply turn on both pumps and this situation can't happen.

gasman · #9 09-09-2012, 02:41 PM

Quote:

Originally Posted by airguy

Another good reason to have electric fuel pumps in each wing root, rather than the engine-driven fuel pump. Simply turn on both pumps and this situation can't happen.

You still need to switch tanks.

With stock configuration, it takes less than 2 seconds for engine to fire when valve is switched.

gasman · #10 09-09-2012, 03:02 PM

Quote:

Originally Posted by WAM120RV

One of our group members did something like this a couple of weeks ago.

Slipped to the left on a low left tank, then did not understand why the engine would not pick up when he applied more throttle. Then when he came out of the slip the engine picked up. He had decided he had enough height and speed to glide in then (so obviously he did not need the extra power when he called for it)ank

So, the next thing he did was killed the engine rather than just pulling back the throttle........ so he left himself with no options at all..... he was now a glider.

Thankfully he pulled off the landing, then restarted the engine and taxied in.

Now!!! all of this could have been avoided by a bit of good airmanship. Simply by selecting the wing high tank before slipping and there is no problem..... so why deliberately try to cause one?

Our man now understands the need to select the higher fuel tank, but does not seem to comprehend the potential problem he caused by killing the engine rather than just closing the throttle????

1. Why would you add power in a slip?
2. Killing the engine????....

only if it was not controllable.
3. Good airmenship needed.
4. Any time you are downwind, you should consider yourself a glider.
5. A distraction like selecting fuel tanks at this point might be frowned upon by your cfi.

Remember, during an engine out emergency landing, the slip will get you to your chosen landing spot. Not the engine.