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Author Topic: Fuel measurement  (Read 2184 times)

Offline Brett Buck

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Fuel measurement
« on: May 29, 2017, 01:28:05 PM »
   Just a note about fueling. When you want to run a fixed amount of fuel, always *fill the tank completely*, then suck out a measured amount. That way, you don't have any question about how much fuel is actually in the tank. If you try to meter in a fixed amount, you never know for sure how much was left after the last flight.

   Brett

« Last Edit: May 30, 2017, 01:35:16 PM by RandySmith »
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Offline Tim Wescott

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Re: Fuel measurement
« Reply #1 on: May 29, 2017, 01:31:15 PM »
Quote from: Brett Buck on May 29, 2017, 01:28:05 PM
   Just a note about fueling. When you want to run a fixed amount of fuel, always *fill the tank completely*, then suck out a measured amount. That way, you don't have any question about how much fuel is actually in the tank. If you try to meter in a fixed amount, you never know for sure how much was left after the last flight.

Based on something this weekend?

I'm not sure who pointed that technique out to me, but it was here, and it's how I do it.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Brett Buck

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Re: Fuel measurement
« Reply #2 on: May 30, 2017, 01:05:19 PM »
Quote from: Motorman on May 30, 2017, 11:15:58 AM
Or you can just empty the tank first.



     Correct, but that's unnecessary if you fill and then suck out, and you still have the problem with getting all of the fuel out of the tank for sure.

    Brett
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Offline Brett Buck

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Re: Fuel measurement
« Reply #3 on: May 30, 2017, 01:06:33 PM »
Quote from: Tim Wescott on May 29, 2017, 01:31:15 PM
Based on something this weekend?


     Yes, but not because of any specific incident.

     Brett
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Offline RandySmith

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Re: Fuel measurement
« Reply #4 on: May 30, 2017, 01:35:33 PM »
Quote from: Brett Buck on May 29, 2017, 01:28:05 PM
  Just a note about fueling. When you want to run a fixed amount of fuel, always *fill the tank completely*, then suck out a measured amount. That way, you don't have any question about how much fuel is actually in the tank. If you try to meter in a fixed amount, you never know for sure how much was left after the last flight.

   Brett





Not nearly as exciting  that way !
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Offline Lauri Malila

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Re: Fuel measurement
« Reply #5 on: May 30, 2017, 02:00:40 PM »
What kind of tank has fuel in it after engine has stopped? Not mine. A Clunk tank?
I only do as Brett suggests when I use my radio cut-off but if I let it run empty, it goes empty.
I fill with a syringe because my tank is so small, but there is a bigger risk of getting all kinds of crap into fuel system.

L
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Offline Paul Smith

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Re: Fuel measurement
« Reply #6 on: May 30, 2017, 03:46:34 PM »
I went through this today.

I flew one flight and it went 8 minutes.

Then I measured in 90 cc and it went 6 minutes.

The amount of unusable fuel after both flights was the same.  So measuring-in worked OK. 

Second issue:  The engine run at the start was not the same as with a full tank.

So the proper fix is to downsize the tank, not start with a partial fuel lead.

If you GO ELECTRIC with a computer controller you will have a BIG advantage over those of us who still need to measure fuel.  One more GOOD reason to never mix electric motors with REAL engines.
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Offline Mark Scarborough

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Re: Fuel measurement
« Reply #7 on: May 30, 2017, 06:19:59 PM »
Quote from: Paul Smith on May 30, 2017, 03:46:34 PM
I went through this today.

I flew one flight and it went 8 minutes.

Then I measured in 90 cc and it went 6 minutes.

The amount of unusable fuel after both flights was the same.  So measuring-in worked OK. 

Second issue:  The engine run at the start was not the same as with a full tank.

So the proper fix is to downsize the tank, not start with a partial fuel lead.

If you GO ELECTRIC with a computer controller you will have a BIG advantage over those of us who still need to measure fuel.  One more GOOD reason to never mix electric motors with REAL engines.
great idea, so a Nats champ makes a practical suggestion, and you blow it off, you dont get the logic then,, and a smaller tank wont always work, what happens when conditions change, and you need a little extra fuel
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Offline Tim Wescott

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Re: Fuel measurement
« Reply #8 on: May 30, 2017, 07:02:19 PM »
Quote from: Mark Scarborough on May 30, 2017, 06:19:59 PM
great idea, so a Nats champ makes a practical suggestion, and you blow it off, you dont get the logic then,, and a smaller tank wont always work, what happens when conditions change, and you need a little extra fuel

Then his motor runs will be consistent, and he won't get to complain about electrics and their "unfair advantages".  So, not an unmitigated win.

Aside from my own stupidity on Saturday, and the electric guy with his "unfair advantage" whose plane pooped out in the outside round loops in Expert, did anyone have an over- or under-run at the Regionals?
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Mark Scarborough

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Re: Fuel measurement
« Reply #9 on: May 30, 2017, 07:22:26 PM »
Quote from: Tim Wescott on May 30, 2017, 07:02:19 PM
Then his motor runs will be consistent, and he won't get to complain about electrics and their "unfair advantages".  So, not an unmitigated win.

Aside from my own stupidity on Saturday, and the electric guy with his "unfair advantage" whose plane pooped out in the outside round loops in Expert, did anyone have an over- or under-run at the Regionals?
did you miss what happened on my second flight of expert in the clover? sheesh dude,, really? I lost a cell in my pack, it went into voltage drop out limp mode as i entered the last loop of the clover,, thats why I pulled through the center instead of over the top
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Offline Tim Wescott

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Re: Fuel measurement
« Reply #10 on: May 30, 2017, 07:41:14 PM »
Quote from: Mark Scarborough on May 30, 2017, 07:22:26 PM
did you miss what happened on my second flight of expert in the clover? sheesh dude,, really? I lost a cell in my pack, it went into voltage drop out limp mode as i entered the last loop of the clover,, thats why I pulled through the center instead of over the top

Did you do the maneuver itself well?  Once you make it past the solid lines in the rule book I'm looking at my score sheet and thinking up a number, then saying "Dragon Lady!!", then writing down something lower.
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AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline RknRusty

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Re: Fuel measurement
« Reply #11 on: May 30, 2017, 07:44:55 PM »
Quote from: Mark Scarborough on May 30, 2017, 06:19:59 PM
great idea, so a Nats champ makes a practical suggestion, and you blow it off, you don't get the logic then,, and a smaller tank won't always work, what happens when conditions change, and you need a little extra fuel
No doubt about it, you have to have enough overhead to allow for conditions. Last weekend at Triple Tree the temp was 25F hotter for second round than it was at 9:30 that morning. I had fueled up with 4 ounces in my 5 oz.tank(using the fill and draw-down method) right after the first round. After lunch, I de-fueled a half ounce when the temp had risen from 65 to 90. Then I leaned the needle an 8th of a turn, because the wind had picked up enough to need more punch. Both flights had 10 laps after the Clover. You have to have wiggle room in both directions. Believe it or not, that's part of what I love about flying IC engines. I love engines and that's just part of the challenge. Just like every other aspect of flying competitively, it makes me feel good when I get it right.
Rusty
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Offline Brett Buck

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Re: Fuel measurement
« Reply #12 on: May 31, 2017, 08:31:34 AM »
Quote from: RandySmith on May 30, 2017, 01:35:33 PM


Not nearly as exciting  that way !


   True enough. Since stunt has become so easy for some of us, we need a new challenge, and random engine run time just puts a bit of excitement back into it.

     Brett

   
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Offline Brett Buck

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Re: Fuel measurement
« Reply #13 on: May 31, 2017, 08:37:38 AM »
Quote from: Paul Smith on May 30, 2017, 03:46:34 PM
I went through this today.

I flew one flight and it went 8 minutes.

Then I measured in 90 cc and it went 6 minutes.

The amount of unusable fuel after both flights was the same.  So measuring-in worked OK.  

Second issue:  The engine run at the start was not the same as with a full tank.

So the proper fix is to downsize the tank, not start with a partial fuel lead.

If you GO ELECTRIC with a computer controller you will have a BIG advantage over those of us who still need to measure fuel.  One more GOOD reason to never mix electric motors with REAL engines.

  Geez, give it a rest already.

   You not knowing how to operate a glow engine reliably doesn't mean that electric should be banned. And what is stopping you from putting in a timer or a 2.4 Ghz RC gadget and cutting it off with the same certainty as an electric - oh, that's right, nothing, and even with the electronics, battery, and rat-trap shutoff, it's still probably lighter than electric. Nobody does it because it's unnecessary if you follow very simple techniques.

     Brett
« Last Edit: May 31, 2017, 09:56:55 AM by Brett Buck »
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Offline Brett Buck

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Re: Fuel measurement
« Reply #14 on: May 31, 2017, 08:51:34 AM »
Quote from: Lauri Malila on May 30, 2017, 02:00:40 PM
What kind of tank has fuel in it after engine has stopped? Not mine. A Clunk tank?
I only do as Brett suggests when I use my radio cut-off but if I let it run empty, it goes empty.
I fill with a syringe because my tank is so small, but there is a bigger risk of getting all kinds of crap into fuel system.


    Even a proper tank can have slightly different amounts of fuel in it depending on how you cut it off (cutoff loop, overheard circling, or letting it run out in level flight), and *many* tanks, particular the ones that are not tapered, leave substantial fuel behind in some conditions. The whole purpose of the cutoff loop, and the way it works, is to cut the engine of when there is still some fuel left. And then there are clunk tanks, which tend to leave some fuel behind AND frequently cannot be cut off consistently.

    A clunk tank is what prompted me to mention the topic, but it's just as true with other types. BTW, since you can see the fuel level in a profile with a clunk, you can just make a mark on the side and use that to determine how much fuel to use.

    BTW, watching profile (and helping a few people with their airplanes) illustrated the fact that people still have a lot of problems getting engines to run properly on profiles, and it's a good thing that someone invented AAC and ABC piston/cylinder assemblies. Because if the profile field at the NWR had been using iron-liner engines, 75% them would have seized up!  One sagging "dead fish" run after another. I started with assisting a couple of guys, but then I started paying attention to the rest of the field, and wow.

     If you are going to put a .305 venturi on a weak-moderate 40, you darn well better have a durable piston and liner!

     Brett
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