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Fuel Consumption

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EAFerguson(at)AOL.COM
Guest

Posted: Tue Sep 18, 2007 9:59 pm Post subject: Fuel Consumption

In response to Buz's comments on fuel consumption.

  

 I did work on fuel consumption for the record trip - quite a bit. With  Nick's help, we played with the jetting for max economy. Here are some results.  

  

 I have a fuel flow device installed. Calibration is somewhat laborious, but  it's now fairly accurate. 

  

 Like Buz, I set power for fuel burn rather than RPM because there is  somewhat less variability. Most legs were close to 4 hours, and with the 20 Gal  in the Lightning, I needed to be under 4.5 GPH. Setting 4.8. on the fuel flow  gave me about that burn rate, T.O. to chocks. I did one leg at 4.2 GPH. 

  

 That power setting gave me about 108K TAS. RPM varied, generally about  2700. The Light Sport version considerably slower than the non-LSA version  with the gear clean up. I also had an extreme cruise prop (borrowed from the  prototype). Flat out I only pulled about 3100 RPM so these numbers may not be  too typical.

  

 I've flown formation with some of the non-LSA Lightning's at SYI and the  speed differential is significant. I had difficulty keeping up with Buz on a  couple of break in flights, even in climb.

  

 We can talk about these numbers this weekend.

 . 

  

 Earl Ferguson

 N17EF



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N1BZRich(at)aol.com
Guest

Posted: Wed Sep 19, 2007 4:05 am Post subject: Fuel Consumption

Earl,

     I am looking forward to your presentation this  weekend.  I am sure you have a lot of good information and data to share  that should be very beneficial for our everyday flight operations.   The time an effort that went into your record flight planning and testing was  probably "many fold" greater than the flight time it took to actually make the  flight.  One of the things I would be really interested in is what you  learned about fuel consumption at various altitudes and power settings.   Based on some of the fuel flow data that I came up with during the initial  40 hour test program and what I am seeing on long cross countries, I really  am beginning to think that the Bing (a great carb) really does not lean as  effectively at the higher altitudes (10,000 and above) as it does down lower  (say below 6 or 8 thousand).     

 Blue Skies,

 Buz



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flying(at)qdea.com
Guest

Posted: Wed Sep 19, 2007 7:42 am Post subject: Fuel Consumption

The Bing carburetor tends to run rich at altitudes above 10,00 feet.



It's also used on Rotax 912's, and the Titan list I also subscribe to 

has discussed this a lot.



In fact, one person sets the needle in the carb one notch leaner 

because she routinely runs at altitudes above 6000 feet.



I guess whoever designed the leaning mechanism decided to err on the 

rich side, which will keep the engine running. Too lean and your 

engine dies.



I have personal experience at 11,500 feet - I concluded that the 

engine was running richer than needed, because I wasn't getting the 

same endurance that I would have expected for the fuel flow rate.



Hugh Sontag



 	  Quote: 	
		  Earl,

     I am looking forward to your presentation this weekend.  I am 

sure you have a lot of good information and data to share that 

should be very beneficial for our everyday flight operations.  The 

time an effort that went into your record flight planning and 

testing was probably "many fold" greater than the flight time it 

took to actually make the flight.  One of the things I would be 

really interested in is what you learned about fuel consumption at 

various altitudes and power settings.  Based on some of the fuel 

flow data that I came up with during the initial 40 hour test 

program and what I am seeing on long cross countries, I really am 

beginning to think that the Bing (a great carb) really does not lean 

as effectively at the higher altitudes (10,000 and above) as it does 

down lower (say below 6 or 8 thousand).   

Blue Skies,

Buz

dashvii(at)hotmail.com
Guest

Posted: Wed Sep 19, 2007 7:56 am Post subject: Fuel Consumption

When I was flying an Esqual during the time that Buz was flying the time off 

of his plane I took it up to about 12,000+ feet.  The whole airplane began 

shaking and I wondered if the prop had hit a bird or something and became 

unbalanced.  I slowed down, checked all my control surfaces and then started 

a descent for a precautionary landing at Shelbyville.  As I passed through 

about 4-5k feet the plane seemed to react much better.  Now keep in mind 

that I still didn't know if it was an airframe or engine issue.  So I went 

ahead and cut in front of Buz who was entereing the pattern the right/safe 

way and made my call for landing.  By the time that I got on the ground I 

couldn't replicate the problem.  Nick did a runup and nothing.  I believe 

that we eventually determined that the pressure compensating mechanism had 

broken on that carb and it went to full rich (which it's supposed to do as I 

understand) and the engine was running so rich that it was shaking the whole 

plane at that altitude!  I'm glad that the engine stayed running, but from 

that altitude I probably could have flown to Nashville and back.  A good way 

to see if the engine is running too rich is to clean the belly of the plane, 

fly for a while and then look at the area just aft of the exhaust and see if 

it's smooty.  Just like every different engine wanted to run at a different 

idle speed to keep it happy, you gotta set up the needle in the carb right.  

Some run a little more lean than other engines.  It's no big deal, but 

something that you want to do in the first 40 to get the best performance 

out of the plane.  Brian W.

From: Hugh Sontag <flying(at)qdea.com>

Reply-To: lightning-list(at)matronics.com

To: lightning-list(at)matronics.com

Subject: Re: Fuel Consumption

Date: Wed, 19 Sep 2007 10:04:09 -0500






The Bing carburetor tends to run rich at altitudes above 10,00 feet.



It's also used on Rotax 912's, and the Titan list I also subscribe to has 

discussed this a lot.



In fact, one person sets the needle in the carb one notch leaner because she 

routinely runs at altitudes above 6000 feet.



I guess whoever designed the leaning mechanism decided to err on the rich 

side, which will keep the engine running. Too lean and your engine dies.



I have personal experience at 11,500 feet - I concluded that the engine was 

running richer than needed, because I wasn't getting the same endurance that 

I would have expected for the fuel flow rate.



Hugh Sontag



 	  Quote: 	
		  Earl,

     I am looking forward to your presentation this weekend.  I am sure you 

have a lot of good information and data to share that should be very 

beneficial for our everyday flight operations.  The time an effort that 

went into your record flight planning and testing was probably "many fold" 

greater than the flight time it took to actually make the flight.  One of 

the things I would be really interested in is what you learned about fuel 

consumption at various altitudes and power settings.  Based on some of the 

fuel flow data that I came up with during the initial 40 hour test program 

and what I am seeing on long cross countries, I really am beginning to 

think that the Bing (a great carb) really does not lean as effectively at 

the higher altitudes (10,000 and above) as it does down lower (say below 6 

or 8 thousand).   Blue Skies,

Buz


	




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N1BZRich(at)aol.com
Guest

Posted: Wed Sep 19, 2007 5:49 pm Post subject: Fuel Consumption

Hugh and all,

     Good info,and it seems to confirm what my data is  showing as to the Bing's leaning at high altitude.  I now have 360 hours on  my 3300 in the past 20 months, and other than the standard oil and filter  changes, head torques, valve adjustments, (new plugs, and new caps and rotors at  250 hours), it has been absolutely trouble tree.  I love the engine, but  would like to have it lean a little more efficiently when at the higher  altitudes.  Heck, I have had it to 16,000 during the 40 hour test program  and it was still climbing at about 400 feet a minute.  (Remember N31BZ has  the longer wings - heck it is almost like a motor glider.)   My feet  were so cold that I decided that was high enough and declared that the service  ceiling was 18,000.  No problems with the engine running smooth up there,  but I had already changed the jetting several times.   

     I have had the Demo Lightning to 14,500 feet just  for grins (it was still climbing almost 400 fpm) and the fact that a current  builder (Dick) lives in Boulder, Colorado, and will need to operate at the  higher elevation airports.  

     One other thought, when you are trying to climb to  the higher altitudes, remember that the higher you go, Vx and Vy get closer  together.  They basically meet at the service ceiling.  Another  thought, if your airplane tells you true airspeed, use that instead of indicated  when climbing at the higher altitudes.  

 Blue Skies,

 Buz



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  [quote][b]

N1BZRich(at)AOL.COM
Guest

Posted: Wed Sep 19, 2007 5:51 pm Post subject: Fuel Consumption

In a message dated 9/19/2007 11:57:20 A.M. Eastern Daylight Time,  dashvii(at)hotmail.com writes:

  	  Quote: 	
		  A good    way to see if the engine is running too rich is to clean the belly of the    plane, 

fly for a while and then look at the area just aft of the exhaust    and see if it's smooty. 	


 

 Good suggestion  from Brian if the exhaust pipe is short and does not  get the exhaust residue away from the fuselage bottom.  For a longer  exhaust pipe just run your finger inside the pipe and if you get black soot,  then you are running too rich.  You really need to check for your  particular airplane.  Just because someone else's Lightning with a certain  carb jet set up is working right, yours might still need a different set  up.  All factors that have to do with how hard the engine is working will  have an effect - which prop you are using and how many drag reduction  efforts you have incorporated into your "bird" will make a difference.   Bottom line, it's part science and part magic.  

 Blue Skies,

 Buz

  

 Attached is a photo I made today of the Prototype Lightning with the latest  drag reduction efforts. 



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N1BZRich(at)aol.com
Guest

Posted: Wed Sep 19, 2007 6:02 pm Post subject: Fuel Consumption

In a message dated 9/19/2007 9:51:36 P.M. Eastern Daylight Time,  N1BZRich(at)aol.com writes:

  	  Quote: 	
		  I now    have 360 hours on my 3300 in the past 20 months, and other than the standard    oil and filter changes, head torques, valve adjustments, (new plugs, and new    caps and rotors at 250 hours), it has been absolutely trouble tree.     	


 

 Just noticed I put the "(" in the wrong place in the above sentence.   Actually I change spark plugs at every 100 hours, and I changed the caps and  rotors at 250 hours.  As to spark plugs, at their price, why clean  them.

 Buz



See what's new atblank">Make AOL Your Homepage.

  [quote][b]

pequeajim

Joined: 03 Sep 2006
Posts: 708
Location: New Holland, PA

Posted: Wed Sep 19, 2007 6:04 pm Post subject: Fuel Consumption

Buz:  

   

You’re such a  tease….  

         

  

From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of N1BZRich(at)aol.com

 Sent: Wednesday, September 19, 2007 9:51 PM

 To: lightning-list(at)matronics.com

 Subject: Re: Fuel Consumption  

  

       

In a message dated 9/19/2007 11:57:20 A.M. Eastern Daylight Time, dashvii(at)hotmail.com writes:  

   	  Quote: 	
		    

A good way to see if the engine is running too rich is to clean the belly of the plane, 

 fly for a while and then look at the area just aft of the exhaust and see if it's smooty.  	
  

    

Good suggestion  from Brian if the exhaust pipe is short and does not get the exhaust residue away from the fuselage bottom.  For a longer exhaust pipe just run your finger inside the pipe and if you get black soot, then you are running too rich.  You really need to check for your particular airplane.  Just because someone else's Lightning with a certain carb jet set up is working right, yours might still need a different set up.  All factors that have to do with how hard the engine is working will have an effect - which prop you are using and how many drag reduction efforts you have incorporated into your "bird" will make a difference.  Bottom line, it's part science and part magic.    

    

Blue Skies,  

    

Buz  

    

   

    

Attached is a photo I made today of the Prototype Lightning with the latest drag reduction efforts.   

  



 

         

  

Make AOL Your Homepage.  

  

       [quote][b]

malannx(at)bigpond.com
Guest

Posted: Thu Sep 20, 2007 5:54 am Post subject: Fuel Consumption

Brian,

  

 If the whole plane was shaking,especially the  wings, you may have had rudder flutter.

  

 A trick some  Rotax drivers use at  altitude is to introduce an air bleed into the induction system. It goes without  saying that you must have EGT on all cyls. The rotax engine has a balance pipe  between the 2 manifolds. Bleed air is introduced there via a needle valve. No  reason why you could not do it to a Jab.

 Requires the same management  the Lycoming  drivers do on every flight.

  

 Malcolm Ferguson

   [quote][b]

dashvii(at)hotmail.com
Guest

Posted: Thu Sep 20, 2007 7:26 am Post subject: Fuel Consumption

"If the whole plane was shaking,especially the wings, you may have had 

rudder flutter."



This turned out not to be the case, but just a rough running engine.  

Waaaayyyyyy too rich at the carb for that altitude.  Flutter was my initial 

concern, so I changed everything, speed, power, attittude, etc.  You can see 

every control surface except for the rudder in the Lightning.  Even then, 

you would feel some feedback from the pedals.  I never experienced flutter 

in any of the planes that I flew there, Jabiru, Esqual, or Lightning.  The 

last two I took out to around 200mph on each airframe.  I did lots of 

different speed/power combinations at different altitudes.  I would be much 

more worried about flutter if you added something to the control surfaces 

themselves, such as your own trim tab.



As far as the engine, that was a rare occassion.  If you read the manual and 

treat the Jabiru as it is supposed to be treated it is a very smooth running 

and reliable engine.  I've never flown a Rotax yet, but this engine is 

smoother than a small Lycoming or Continental, such as the O-200.  As Buz 

said, set the autopilot, try not to fall asleep!  Brian W.

From: "Malcolm Ferguson" <malannx(at)bigpond.com>

Reply-To: lightning-list(at)matronics.com

To: <lightning-list(at)matronics.com>

Subject: Re: Fuel Consumption

Date: Thu, 20 Sep 2007 23:53:05 +1000



Brian,



If the whole plane was shaking,especially the wings, you may have had rudder 

flutter.



A trick some  Rotax drivers use at altitude is to introduce an air bleed 

into the induction system. It goes without saying that you must have EGT on 

all cyls. The rotax engine has a balance pipe between the 2 manifolds. Bleed 

air is introduced there via a needle valve. No reason why you could not do 

it to a Jab.

Requires the same management  the Lycoming drivers do on every flight.



Malcolm Ferguson



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