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Fuel Flow at Cruise
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jim

Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho

Posted: Thu Jan 25, 2007 11:36 am Post subject: Fuel Flow at Cruise

What sort of cruise fuel flows do you get?  I haven't flown my Firefly long enough or far enough to know.  I was looking at the Rotax data sheets and they indicate 4.5 to 5.5 gph for a 447 or 503 in cruise.  I though folks got more like 2gph???



What are your cruise fuel flows (preferably with associated airspeed)?

_________________
Jim
N. Idaho

David.Lehman

Joined: 10 Jan 2006
Posts: 265
Location: "Lovely" Fresno CA

Posted: Thu Jan 25, 2007 12:03 pm Post subject: Fuel Flow at Cruise

Original dirty Firestar...

  

 3-3.5+/- GPH, single carb. 503, indicate 67(at)SL ([email]67(at)SL[/email])...

  

 4-4.5+/- GPH, dual carb. 503, indicate 67(at)SL ([email]67(at)SL[/email])...

  

 DVD



 

 On 1/25/07, jim <jim(at)tru-cast.com (jim(at)tru-cast.com)> wrote: [quote]--> Kolb-List message posted by: "jim" <jim(at)tru-cast.com  (jim(at)tru-cast.com)>



What sort of cruise fuel flows do you get?  I haven't flown my Firefly long enough or far enough to know.  I was looking at the Rotax data sheets and they indicate 4.5 to 5.5 gph for a 447 or 503 in cruise.  I though folks got more like 2gph??? 



What are your cruise fuel flows (preferably with associated airspeed)?



--------

Jim

N. Idaho

[b]

_________________
Ã´Â¿Ã´

"Both optimists and pessimists contribute to the society. The optimist invents the aeroplane, the pessimist the parachute."

--- George Bernard Shaw

tkrolfe(at)usadatanet.net
Guest

Posted: Thu Jan 25, 2007 12:29 pm Post subject: Fuel Flow at Cruise

jim wrote:



 	  Quote: 	
		  



What sort of cruise fuel flows do you get?  I haven't flown my Firefly long enough or far enough to know.  I was looking at the Rotax data sheets and they indicate 4.5 to 5.5 gph for a 447 or 503 in cruise.  I though folks got more like 2gph???



What are your cruise fuel flows (preferably with associated airspeed)?



--------

Jim

N. Idaho



  




	


Jim, 



I get about 2 gph on my FireFly.  I swing a 66" Tennessee Prop and can 

go about 120 miles before having to set down for more fuel depending on 

the air density and my flying maneuvers.  Great mileage now, but cold!!!!!



Enjoy your FireFly!!!



Terry - FireFly #95

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Thu Jan 25, 2007 1:18 pm Post subject: Fuel Flow at Cruise

MKIII Rotax 582, B box 2.58:1 Ivo 2 blade, 68"

About 3.5 gph at 65 mph at 5200 rpm



FSII Rotax 582, E box 2.62:1 Ivo 2 blade 68"

About 3 gph at 65 mph at 4800 rpm



Fuel flow is a function of rpm & load.

Streamline the airframe, and rpm's drop for a given speed.

As rpm's drop, fuel flow goes down.

A big engine loafing is preferable to a little one screaming, it's quieter 

and doesn't use any more fuel, sometimes it uses less fuel.



Richard Pike

MKIII N420P (420ldpoops)

---

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

jim

Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho

Posted: Thu Jan 25, 2007 2:14 pm Post subject: Fuel Flow at Cruise

I don't know how Rotax took their measurements, but their 447 graphs shows

no change in fuel flow (5.3gph) from 5500 rpm (35HP) to 7000 rpm (40HP).



My Firefly has a 503 DCDI.  Rotax fuel flow figures for this engine make

more sense in that they follow RPM/HP to max RPM.  But it still shows fuel

flow at 4.8gph (at) 4500 rpm (27HP) to 5.8gph (at) 6500 rpm (50HP).  Even with

short flights it seems my fuel flow is not more than 3 gph at 60 mph.

 	  Quote: 	
		   Fuel flow is a function of rpm & load.

 Streamline the airframe, and rpm's drop for a given speed.

 As rpm's drop, fuel flow goes down.

 A big engine loafing is preferable to a little one screaming, it's quieter

 and doesn't use any more fuel, sometimes it uses less fuel.



 Richard Pike

 MKIII N420P (420ldpoops)

_________________
Jim
N. Idaho

knowvne(at)aol.com
Guest

Posted: Thu Jan 25, 2007 2:58 pm Post subject: Fuel Flow at Cruise

Hey  Richard

With the 503 DC on the Firefly are you still 103 legal or did you bust 

the weight limits?

All I've ever read about on a Fireflyis the smaller 447...



Thanks



Mark Vaughn



--

jim

Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho

Posted: Thu Jan 25, 2007 3:37 pm Post subject: Fuel Flow at Cruise

The Firefly is over 254# with the 503.  Even with the 447 you can only

have 1 carb, a 2-bladed wood prop, 4" wheels, no brakes, no oil injection,

no electrical, no or minimal instruments, and minimal paint.  I think you

may also have to cover the wings with toilet paper instead of Polyfiber.



If I had built it I would have put on a 447.  The guy I bought it from had

a new 503 already so he bought the Firefly and put his engine on it.



[quote] 



 Hey  Richard

 With the 503 DC on the Firefly are you still 103 legal or did you bust

 the weight limits?

 All I've ever read about on a Fireflyis the smaller 447...



 Thanks



 Mark Vaughn



 --

_________________
Jim
N. Idaho

ElleryWeld(at)aol.com
Guest

Posted: Thu Jan 25, 2007 6:36 pm Post subject: Fuel Flow at Cruise

I get 2.5 an hour  not pushing it with my 447 Rotax on a Firestar and that is using a NAVMAN Fuel flow meter 

 

 Ellery

 do not archive  [quote][b]

DAquaNut(at)aol.com
Guest

Posted: Thu Jan 25, 2007 7:11 pm Post subject: Fuel Flow at Cruise

In a message dated 1/25/2007 2:31:01 P.M. Central Standard Time,  tkrolfe(at)usadatanet.net writes:

  	  Quote: 	
		  

I    get about 2 gph on my FireFly.  I swing a 66" Tennessee Prop and can    

go about 120 miles before having to set down for more fuel depending on    

the air density and my flying maneuvers.  Great mileage now, but    cold!!!!!



Enjoy your FireFly!!!



Terry - FireFly    #95



	


 

                         Terry,

  

                What speed are you cruising to get 2 gph?  I burn  3.5- 3.45 gph at  60-65 mph

  

                Ed (In Houston  FF#62)  Where we had A sunny day for the first time in  2 weeks!

  [quote][b]

Earl Zimmerman

Joined: 13 Jan 2006
Posts: 35
Location: Elizabethtown, PA

Posted: Thu Jan 25, 2007 7:39 pm Post subject: Fuel Flow at Cruise

Jim Dunn wrote:



 	  Quote: 	
		   My Firefly has a 503 DCDI. 

  Wow! That ought to be a wild ride! Wish I had one.     ~ Earl

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Jan 25, 2007 7:54 pm Post subject: Fuel Flow at Cruise

| > My Firefly has a 503 DCDI. 

|  Wow! That ought to be a wild ride! Wish I had one.     ~ Earl

 



Earl:



I get a rush flying a 447 FF.  The 503 would blow my mind.



john h

mkIII



DO NOT ARCHIVE

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

tkrolfe(at)usadatanet.net
Guest

Posted: Fri Jan 26, 2007 6:37 am Post subject: Fuel Flow at Cruise

DAquaNut(at)aol.com (DAquaNut(at)aol.com) wrote:  	  Quote: 	
		                 In a message dated 1/25/2007 2:31:01 P.M. Central Standard Time, tkrolfe(at)usadatanet.net (tkrolfe(at)usadatanet.net) writes:

    	  Quote: 	
		  

 I get about 2 gph on my FireFly.  I swing a 66" Tennessee Prop and can 

 go about 120 miles before having to set down for more fuel depending on     

 the air density and my flying maneuvers.  Great mileage now, but cold!!!!!

     

 Enjoy your FireFly!!!

     

 Terry - FireFly #95

     

     	
   

                          Terry,

    

                 What speed are you cruising to get 2 gph?  I burn  3.5- 3.45 gph at 60-65 mph

    

                 Ed (In Houston  FF#62)  Where we had A sunny day for the first time in 2 weeks!

       	  Quote: 	
		  

	
 	
 

 Ed,

 

 What's your hurry?  I like to fly slow and gawk, that's why I built a FireFly ultralight.  I normally cruise at 5,000 to 5,200 rpm which translates into 50 mph to 52 mph.   Sometimes at 4,800 rpm if interested in a particular place and want to enjoy.  I can go faster, but don't need to.  Flying for pleasure, not to get somewhere.  This is with an open cockpit, probably could do a little better with a full enclosure.  Also, the number of takeoff's really increases the fuel burn rate.

 

 Fuel consumption goes up in mid summer with the loss of air density.

 

 Terry -  FireFly #95

     [quote][b]

jim

Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho

Posted: Fri Jan 26, 2007 8:50 am Post subject: Fuel Flow at Cruise

It performs pretty well with the 503 but I haven't flown a FF with a 447

to compare it with.  The previous owner cut a new IVO 3-bladed prop down

to 54" diameter.  Performance would probably be better with a new 62"

3-bladed Ivo, but I'm not sure it would be worth $550+ to find out.  I

have a used Ivo Left hand prop in great condition (3 blades only) if

someone wants to trade with me I can find out.  This Spring I will do more

flying, testing, and tweeking to try to determine its performance.  There

is also another Firefly owner about 90 miles N of me.  Maybe we could get

together for a race to 5000'.  I have seen his plane fly (with 2-bladed

Tenessee prop) and I think he would win.



BTW, I really like the oil injection.  It saves a lot of mess and now if I

don't use my UL fuel fast enough, I can dump it in my car.  I can also buy

Avgas on a XC without the mess and worry of mixing correctly.

 	  Quote: 	
		    | > My Firefly has a 503 DCDI.

 |  Wow! That ought to be a wild ride! Wish I had one.     ~ Earl

 Earl:



 I get a rush flying a 447 FF.  The 503 would blow my mind.



 john h

 mkIII



 DO NOT ARCHIVE

_________________
Jim
N. Idaho

Earl Zimmerman

Joined: 13 Jan 2006
Posts: 35
Location: Elizabethtown, PA

Posted: Fri Jan 26, 2007 11:42 am Post subject: Fuel Flow at Cruise

Jim Dunn wrote:

 	  Quote: 	
		   

 

 It performs pretty well with the 503 but I haven't flown a FF with a 447

 to compare it with.  The previous owner cut a new IVO 3-bladed prop down

 to 54" diameter.  Performance would probably be better with a new 62"

 3-bladed Ivo, but I'm not sure it would be worth $550+ to find out. 


	


Put a two blade 66" or 68" prop. on and it would be a pocket rocket!

I fly with a guy who has FF with 447 two blade IVO 62" or 64", and the 

older larger cord ailerons and I believe his climb rate is well over 

1000 fpm.     ~ Earl

1planeguy(at)kilocharlie.
Guest

Posted: Fri Jan 26, 2007 12:44 pm Post subject: Fuel Flow at Cruise

So your telling me that same plane, same engine, same airspeed got 1 GPH better fuel consumption with a single carb instead of 2?    

   

Jeremy  

   

--

jim

Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho

Posted: Fri Jan 26, 2007 12:51 pm Post subject: Re: Fuel Flow at Cruise

I don't think a 66 or 68" 2-bladed prop will fit in the enclosed trailer that came with the Firefly.  After I get everything the way I want it and the weather warms up, I'll make some quantitative tests.  If it doesn't do at least 1000fpm ROC with the existing prop, I will probably go to the longest 3-bladed prop that will fit in the trailer (I'm hoping 62").  



From what I've heard, 3 bladed props give better climb and 2-bladed better cruise.  With the FF climb performance is not a problem so I'd rather have a 2-bladed prop to reduce weight and increase cruise.  Unfortunately, if need to go to a new one I think space requirements will dictate a 3-bladed prop.



Thanks,

Jim

_________________
Jim
N. Idaho

David.Lehman

Joined: 10 Jan 2006
Posts: 265
Location: "Lovely" Fresno CA

Posted: Fri Jan 26, 2007 1:01 pm Post subject: Fuel Flow at Cruise

That's correct...

  

 Big difference is in takeoff roll and initial ROC...  Same 66X34 Tennessee woody gives me 6800 RPM with two carbs., 6400 RPM with one...

  

 DVD



 

 On 1/26/07, Jeremy Casey <1planeguy(at)kilocharlie.us (1planeguy(at)kilocharlie.us)> wrote: [quote]   

So your telling me that same plane, same engine, same airspeed got 1 GPH better fuel consumption with a single carb instead of 2?    

  

Jeremy 

 



[b]

_________________
Ã´Â¿Ã´

"Both optimists and pessimists contribute to the society. The optimist invents the aeroplane, the pessimist the parachute."

--- George Bernard Shaw

d-m-hague(at)comcast.net
Guest

Posted: Fri Jan 26, 2007 2:19 pm Post subject: Fuel Flow at Cruise

At 03:51 PM 1/26/2007, jim wrote:



 	  Quote: 	
		  I don't think a 66 or 68" 2-bladed prop will fit in the enclosed trailer 

that came with the Firefly...


	


How can you fold the wings with a 3-blade prop?



 	  Quote: 	
		   From what I've heard, 3 bladed props give better climb and 2-bladed 

 better cruise...


	


That sorta makes sense.  All other things being equal, a 2-blade prop is 

more efficient (a 1 blade is even better, but obviously raises other 

issues).  However, if you're limited by diameter for how much power the 

prop can absorb, adding a blade will give better full throttle 

performance.  At reduced cruise power settings, the efficiency gain of the 

2-blade is more important.



                                 -Dana

--

--

People in cars cause accidents. Accidents in cars cause people.

mdnanwelch7(at)hotmail.co
Guest

Posted: Fri Jan 26, 2007 4:16 pm Post subject: Fuel Flow at Cruise

Ah ha Jim!

   There's your problem....you have to wait for the weather to warm up!!!   

HeHe

             Mike in Utah (60 degrees today, I actually started sweating 

while doing tractor work)

 	  Quote: 	
		  From: "jim" <jim(at)tru-cast.com>

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

To: kolb-list(at)matronics.com

Subject: Re: Fuel Flow at Cruise

Date: Fri, 26 Jan 2007 12:51:40 -0800






I don't think a 66 or 68" 2-bladed prop will fit in the enclosed trailer 

that came with the Firefly.  After I get everything the way I want it and 

the weather warms up, I'll make some quantitative tests.  If it doesn't do 

at least 1000fpm ROC with the existing prop, I will probably go to the 

longest 3-bladed prop that will fit in the trailer (I'm hoping 62").



 >From what I've heard, 3 bladed props give better climb and 2-bladed 

better cruise.  With the FF climb performance is not a problem so I'd 

rather have a 2-bladed prop to reduce weight and increase cruise.  

Unfortunately, if need to go to a new one I think space requirements will 

dictate a 3-bladed prop.



Thanks,

Jim



--------

Jim

N. Idaho





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=90680#90680






	


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DAquaNut(at)aol.com
Guest

Posted: Fri Jan 26, 2007 4:54 pm Post subject: Fuel Flow at Cruise

In a message dated 1/26/2007 8:38:35 A.M. Central Standard Time,  tkrolfe(at)usadatanet.net writes:

  	  Quote: 	
		  

Ed,



What's your hurry?  I like to fly slow and gawk,    that's why I built a FireFly ultralight.  I normally cruise at 5,000 to    5,200 rpm which translates into 50 mph to 52 mph.   Sometimes at    4,800 rpm if interested in a particular place and want to enjoy.  I can    go faster, but don't need to.  Flying for pleasure, not to get    somewhere.  This is with an open cockpit, probably could do a little    better with a full enclosure.  Also, the number of takeoff's really    increases the fuel burn rate.



Fuel consumption goes up in mid summer    with the loss of air density.



Terry -  FireFly #95

 	  Quote: 	
		         Terry, 	
	
      When you said you could go 120 miles before  refueling, I assumed you were flying to get somewhere. So you figure if I held  my RPMS to 5200 I should be able to go 100 miles on a tank? I havent tried going  that slow when going cross country!

 	  Quote: 	
		  

           Ed (Firefly #62)            	
 

     

  [quote][b]

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