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Most economical cruse speed

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DAquaNut(at)aol.com
Guest

Posted: Sun Feb 04, 2007 8:19 pm Post subject: Most economical cruse speed

Fire- Flyers,

  

   Has anyone done any research or testing or even guessing as to what  RPMs give the most economy and most range with a 66" Ivo and a 447 on the  Firefly?  Best I can tell my range is no more than about 50 to 54 miles on  4.5 gallons.  Any one do any better than that on a 5 gallon tank?  I  could find nothing on the subject in the Archives .

  

        Ed ( in Houston where it is starting  to Dry out a little) 

  [quote][b]

herbgh

Joined: 10 Jan 2006
Posts: 145

Posted: Mon Feb 05, 2007 7:54 am Post subject: Most economical cruse speed

Ed

  

    I fly with a two blade 62 inch ivo with minimum pitch..Have a  points 447--came brand new with the second hand kit.. Never could get the engine  to swing a three blade 66 inch ivo... no matter the pitch.. Std jets...

  

    Flies very satisfactorily on the 62 incher... here are some  log book entries... have hobbs..meter..  62 miles   1.5 hours...  4 take offs and landings..   3.05 gals and 62 miles...   7-3-2006   another....   Home to Glasgow to Hodgenville to  Glasgow to home... 132.4 miles 6.25 gals.  Flew with another Firefly and  likely spent most of our time at 5200 rpms?  I like to run abt 5800  rpms..     8-19-2006..   nuther.... home to  Glasgow to Rough River state park(ky state EAA flyin) to Glasgow to  home...   3.20 hours---8.9 gals  173 miles.. spent abt 10 miles  dodging storm.... 9-9-2006...    lastly  home to No Bob to  Wildwood to Welcome to home... 2 hours... 5.5 gals   106 miles...  10-7-2006..     

  

    Looks as if I burn in the nieghborhood of  2.2 to 2.75  gals an hour..  average  abt 20 mpg..  Herb

  

  

  

  

 On Sun, 4 Feb 2007 23:18:15 EST DAquaNut(at)aol.com (DAquaNut(at)aol.com) writes:

 [quote]     Fire- Flyers,

    

     Has anyone done any research or testing or even guessing as to    what RPMs give the most economy and most range with a 66" Ivo and a 447 on the    Firefly?  Best I can tell my range is no more than about 50 to 54 miles    on 4.5 gallons.  Any one do any better than that on a 5 gallon    tank?  I could find nothing on the subject in the Archives .

    

          Ed ( in Houston where it is starting    to Dry out a little) 

 	  Quote: 	
		  



http://www.matronics.com/Navigator?Kolb-List

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[b]

jimhefner

Joined: 11 Jan 2006
Posts: 91
Location: Tucson, AZ

Posted: Mon Feb 05, 2007 10:03 am Post subject: Re: Most economical cruse speed

Ed, my old Firefly had a 66" IVO with pitch set for 6200 static.  I usually cruised at 5100 - 5300 rpms and based on GPS trip summaries and fuel used, I tended to see 20 mpg avg, which was just under 3 gal/hr cruising 55-60.  Hope that helps.

_________________
Jim Hefner
Tucson, AZ
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Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Mon Feb 05, 2007 1:34 pm Post subject: Most economical cruse speed

DAuquaNut,



I cannot tell you about FireFlys per se but can tell you that for the 

lowest fuel consumption per mile flown in calm winds generally occurs 

fairly close to Vy, best rate of climb speed in most airplanes. The 

least fuel consumption per hour of flight generally occurs at a lower 

speed closer to Vx, best angle of climb speed.  If you know those 

speeds you will be pretty close to what you are looking for if airspeed 

is what you want.



If engine speed is what you want, the older Rotax manuals used to have 

a specific fuel consumption chart for all their engines which indicated 

at what engine speed you could expect to make the most 

horsepower/gallon of fuel used. I've not seen one of these charts in a 

very long time. Since they now show HP charts and fuel consumption 

charts (at full load) you could do some math by dividing the GPH by HP 

to come up with your own version of this specific fuel consumption 

data. But it would not do you much good since that would be valid at 

full load only and would not tell you much about partial load cruising. 

The V speeds will give you closer guestimate for that purpose.



If you have a fuel flow gage, then you could do your own tests.



Thom in Buffalo

Freezing my "do not archive" off

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

planecrazzzy
Guest

Posted: Mon Feb 05, 2007 3:13 pm Post subject: Re: Most economical cruse speed

I have a Fuel Flow meter / Fuel gauge  , I switch over to see the fuel flow alot....I'm suprised how high it can get....When I'm cruising I check to see if I'm pushing it too much....Backing off the throttle "just a little" can really save the fuel.... I don't know how you could tell otherwise....

 Conditions change too much....



  I like that Fuel Flow meter !



                                           Gotta Fly...

                                                           Mike in MN

jim

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

Posted: Mon Feb 05, 2007 5:32 pm Post subject: Most economical cruse speed

So Mike, what are the numbers?

 	  Quote: 	
		  

 I have a Fuel Flow meter / Fuel gauge  , I switch over to see the fuel

 flow alot....I'm suprised how high it can get....When I'm cruising I check

 to see if I'm pushing it too much....Backing off the throttle "just a

 little" can really save the fuel

_________________
Jim
N. Idaho

Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Tue Feb 06, 2007 5:30 am Post subject: Most economical cruse speed

Has anyone considered that as you reduce the rpms on a 447 below 5800 that  you are dropping off the tuned rpm for the exhaust pipe and you may be  increasing wear and adding carbon to the rings?

  

 steve

  [quote][b]

John Hauck

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

Posted: Tue Feb 06, 2007 5:57 am Post subject: Most economical cruse speed

| Has anyone considered that as you reduce the rpms on a 447 below 

5800 that

| you are dropping off the tuned rpm for the exhaust pipe and you may 

be

| increasing wear and adding carbon to the rings?

|

| steve

|



Morning Steve:



I have, but the majority of the Kolb List wants to make JD tractors 

out of them.  Something about wearing them out sooner if you turn more 

rpm, even though the engine was designed to cruise at 5,800 rpm and 

above.  It is a continuous duty engine that does much better at or 

above 5,800 rpm.  Without going back to look it up, the engine is 

capable of 6,500 rpm max continuous.



Lots of folks feel the same way about the 912 series engines that are 

5,500 rpm max continuous.  In my case, if I don't turn at least 5,000 

rpm, I can not keep the engine oil and CHT up to minimum temps.



Wonder if we could put my 1936 JD D engine on a Firestar.  It gets its 

max hp at 900 rpm.



john h

mkIII

25F and sunny

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

ul15rhb(at)juno.com
Guest

Posted: Tue Feb 06, 2007 6:23 am Post subject: Most economical cruse speed

John and others, I am flying my Firestar with a 5100 RPM cruise every 

time I fly. I have over 450 hours on the 447. I'm a believer that 

less RPM's equates to less wear. So far, so good.



Ralph Burlingame

Original Firestar/447

20 years flying it

-- "John Hauck" <jhauck(at)elmore.rr.com> wrote:




| Has anyone considered that as you reduce the rpms on a 447 below 

5800 that

| you are dropping off the tuned rpm for the exhaust pipe and you may 

be

| increasing wear and adding carbon to the rings?

|

| steve

|



Morning Steve:



I have, but the majority of the Kolb List wants to make JD tractors 

out of them.  Something about wearing them out sooner if you turn 

more 

rpm, even though the engine was designed to cruise at 5,800 rpm and 

above.  It is a continuous duty engine that does much better at or 

above 5,800 rpm.  Without going back to look it up, the engine is 

capable of 6,500 rpm max continuous.



Lots of folks feel the same way about the 912 series engines that are 

5,500 rpm max continuous.  In my case, if I don't turn at least 5,000 

rpm, I can not keep the engine oil and CHT up to minimum temps.



Wonder if we could put my 1936 JD D engine on a Firestar.  It gets 

its 

max hp at 900 rpm.



john h

mkIII

25F and sunny 



________________________________________________________________________

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planecrazzzy
Guest

Posted: Tue Feb 06, 2007 3:00 pm Post subject: Re: Most economical cruse speed

Hi Jim,

          Just like a Detroit Diesel, I keep'r scream'n



 Mostly around 5900 - 6000



 I don't really get good GPH .... But sometimes when I see the Fuel flow

at 6 plus GPH , I back it down....Some of that is during climb



 But even at cruise I see 5 gph sometimes



 If I try for 3.5 gph like they say it's suppose to get ,  My RPM's would be way too low....



With a slight headwind I can almost go 100 miles on 8 gals , That's a 2 gal reserve ( doesn't mean 1 gal in each tank - uneven )

.

.



                      Gotta Fly...

                                      Mike & "Jaz" in MN

.

.

.





 	  jim wrote: 	
		  So Mike, what are the numbers?

 	  Quote: 	
		  

 I have a Fuel Flow meter / Fuel gauge  , I switch over to see the fuel

 flow alot....I'm suprised how high it can get....When I'm cruising I check

 to see if I'm pushing it too much....Backing off the throttle "just a

 little" can really save the fuel

icrashrc

Joined: 16 Mar 2006
Posts: 247
Location: Mishawaka, In

Posted: Wed Feb 07, 2007 2:18 am Post subject: Re: Most economical cruse speed

Wonder if we could put my 1936 JD D engine on a Firestar.  It gets 

its 

max hp at 900 rpm.



john h

___________________________________________________________



If you're aiming for economy you should run the JD closer to max torque. I would aim for about 500rpm on the 'D'. Might wanna add a few pounds of air to the Firestars tires as well!

_________________
Scott

www.ill-EagleAviation.com

do not archive

jimhefner

Joined: 11 Jan 2006
Posts: 91
Location: Tucson, AZ

Posted: Wed Feb 07, 2007 8:54 am Post subject: Re: Most economical cruse speed

Has anyone considered that as you reduce the rpms on a 447 below 5800 that you are dropping off the tuned rpm for the exhaust pipe and you may be increasing wear and adding carbon to the rings? 



steve 



Steve, I don't know about your 447 or your setup but I know based on a couple hundred hours of experience that this was not a problem.  As power was reduced on approach I had to avoid the 4200-4400rpm range, where the exhaust tuning is a problem, causing EGT's to go up sharply, but other than that, there was no problem.  The 447 has plenty of power so even though at lower rpm settings it is not up on the high end of the power curve , there is plenty of power for a comfortable cruise speed.  The engine was not laboring a bit... more like purring like a kitten.  I used 100:1 synthetic so there was no carbon build-up and looking at the rings through the exhaust port, they were clean and free.... not a slap mark on either piston after more than 200 hrs.... looked new inside!  A friend once looked into my exhaust ports and couldn't believe how clean and new it looked.  My EGT's were 1050 and CHT was 225.... I don't think there was much wear going on there.    



I know there are always debates on this topic and everyone has a right to their own views and you all can run your engines at 5800 or above at cruise all you want, just sharing my experience with the list for those that might want to try something similar.  I always burned a little under 3 gal/hr using that approach and setup.... a 447 shouldn't be burning much more than 3 gph or something is not right with the setup in my opinion.



Steve, what are your numbers?  (GPH, EGT/CHT, cruise speed, static rpm)

_________________
Jim Hefner
Tucson, AZ
Do Not Archive

ul15rhb(at)juno.com
Guest

Posted: Wed Feb 07, 2007 9:17 am Post subject: Most economical cruse speed

I'm in 100% agreement with Jim on this topic. 5000-5100 RPM is where 

the best economy is for the 447 on the Firestar or Firefly at about 

2.5 to 2.7 gallons per hour.



Ralph Burlingame

Original Firestar w/447

20 years flying it

-- "jimhefner" <hefner_jim(at)msn.com> wrote:




Has anyone considered that as you reduce the rpms on a 447 below 5800 

that you are dropping off the tuned rpm for the exhaust pipe and you 

may be increasing wear and adding carbon to the rings? 



steve 



Steve, I don't know about your 447 or your setup but I know based on 

a couple hundred hours of experience that this was not a problem.  As 

power was reduced on approach I had to avoid the 4200-4400rpm range, 

where the exhaust tuning is a problem, causing EGT's to go up 

sharply, but other than that, there was no problem.  The 447 has 

plenty of power so even though at lower rpm settings it is not up on 

the high end of the power curve , there is plenty of power for a 

comfortable cruise speed.  The engine was not laboring a bit... more 

like purring like a kitten.  I used 100:1 synthetic so there was no 

carbon build-up and looking at the rings through the exhaust port, 

they were clean and free.... not a slap mark on either piston after 

more than 200 hrs.... looked new inside!  A friend once looked into 

my exhaust ports and couldn't believe how clean and new it looked.  

My EGT's were 1050 and CHT was 225.... I don't think there was much 

wear going on there.    



I know there are always debates on this topic and everyone has a 

right to their own views and you all can run your engines at 5800 or 

above at cruise all you want, just sharing my experience with the 

list for those that might want to try something similar.  I always 

burned a little under 3 gal/hr using that approach and setup.... a 

447 shouldn't be burning much more than 3 gph or something is not 

right with the setup in my opinion.



Steve, what are your numbers?  (GPH, EGT/CHT, cruise speed, static 

rpm)



--------

Jim Hefner

Kolbless in Tucson  

Do Not Archive





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http://forums.matronics.com/viewtopic.php?p=93447#93447





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Richard Pike

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

Posted: Wed Feb 07, 2007 11:25 am Post subject: Most economical cruse speed

The Rotax 532 had a noticable "on the  pipe/off the pipe" range that fell in the lower 5000 rpm range, and years ago I  used to fly a Quicksilver MX with a 377 that had a very noticable range where it  was either on or off the pipe. It is easy to tell engines affected in this  manner because they will not hold a constant rpm, but will gain or lose rpm  within certain rpm ranges. The 90 series 582 I am using does not do that that I  have ever noticed, and I understand that the blue head is even better about it.  So being on/falling off the pipe is not a factor. 

 Last annual, rings were clean &  free, top of piston was very lightly carboned, underside of head had a couple  carbon patches about as big as a fingernail, a couple small streaks of carbon  buildup in the exhaust manifold. Left it all alone, put it back  together.

 Using Phillups Injex, normally cruise  around 5100-5300 solo, 5500-5600 with a passenger. Quiet and comfortable at  around 63 mph.

  

 Richard Pike

 MKIII N420P (420ldPoops)

 [quote]   ---

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

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

tkrolfe(at)usadatanet.net
Guest

Posted: Wed Feb 07, 2007 11:29 am Post subject: Most economical cruse speed

Ralph wrote:



 	  Quote: 	
		  



I'm in 100% agreement with Jim on this topic. 5000-5100 RPM is where 

the best economy is for the 447 on the Firestar or Firefly at about 

2.5 to 2.7 gallons per hour.



Ralph Burlingame

Original Firestar w/447

20 years flying it

-- "jimhefner" <hefner_jim(at)msn.com> wrote:




Has anyone considered that as you reduce the rpms on a 447 below 5800 

that you are dropping off the tuned rpm for the exhaust pipe and you 

may be increasing wear and adding carbon to the rings? 



steve 



Steve, I don't know about your 447 or your setup but I know based on 

a couple hundred hours of experience that this was not a problem.  As 

power was reduced on approach I had to avoid the 4200-4400rpm range, 

where the exhaust tuning is a problem, causing EGT's to go up 

sharply, but other than that, there was no problem.  The 447 has 

plenty of power so even though at lower rpm settings it is not up on 

the high end of the power curve , there is plenty of power for a 

comfortable cruise speed.  The engine was not laboring a bit... more 

like purring like a kitten.  I used 100:1 synthetic so there was no 

carbon build-up and looking at the rings through the exhaust port, 

they were clean and free.... not a slap mark on either piston after 

more than 200 hrs.... looked new inside!  A friend once looked into 

my exhaust ports and couldn't believe how clean and new it looked.  

My EGT's were 1050 and CHT was 225.... I don't think there was much 

wear going on there.    



I know there are always debates on this topic and everyone has a 

right to their own views and you all can run your engines at 5800 or 

above at cruise all you want, just sharing my experience with the 

list for those that might want to try something similar.  I always 

burned a little under 3 gal/hr using that approach and setup.... a 

447 shouldn't be burning much more than 3 gph or something is not 

right with the setup in my opinion.



Steve, what are your numbers?  (GPH, EGT/CHT, cruise speed, static 

rpm)



--------

Jim Hefner

Kolbless in Tucson  

Do Not Archive



  




	


Jim, Steve,



I guess that was what I was trying to get across earlier in my reply to 

Ed with his FireFly.  Seems nobody want's to believe 2 or 2.25 gal/hr. 

on a 447.  Flying at 5,000 to 5,200 rpm in front of a Tennessee wood 

prop for 620 hr's.



Terry -  Firefly #95

jimhefner

Joined: 11 Jan 2006
Posts: 91
Location: Tucson, AZ

Posted: Wed Feb 07, 2007 9:59 pm Post subject: Re: Most economical cruse speed

Terry, if you are only burning  2- 2.25 gph, you are doing better than I ever did.  I averaged around 2.75 with the 66" IVO on the FF.  Sounds like you have a good thing going, so don't change anything.  How long is your Tennessee prop?

_________________
Jim Hefner
Tucson, AZ
Do Not Archive

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Thu Feb 08, 2007 5:06 am Post subject: Most economical cruse speed

When I was flying an early Firestar with 377 engine, I typically 

cruised at about 5200 rpm when I was enjoying the scenery, which 

yielded about 45-50 mph, which is the speed I flew at much of the time. 

  When trying to set somewhere, I'd push it up to 5600-5800 rpm for a 

55-60 mph cruise. I kept complete records on total fuel consumption for 

the time I had this airplane and the average fuel consumption over that 

time was 2.8 gph and had no engine problems whatsoever during that 

time.



Thom in Buffalo

do not archive

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

John Hauck

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

Posted: Thu Feb 08, 2007 6:37 am Post subject: Most economical cruse speed

Morning Gang:



I have discovered there are two modes of flight to determine fuel 

consumption.



1-Flying around the patch.



2-Cross country.



Flying around the patch burns about 50 to 75% of the fuel that you 

burn cross country.



If you want a true fuel burn, it is best, in my opinion, to fly some 

cross country.  Most important info is time of flight and maintaining 

"your" cruise rpm, except for take off and landings.  Probably should 

fly, at least, one hour legs to verify fuel burn.  Fuel tank should be 

topped off prior to the flight and topped off again when you complete 

your flight.  You will be surprised how much fuel you burn, if you 

have never done a fuel check before.



Remember, flying and playing around the patch will give you much 

better fuel consumption than flying a true cross country flight.



john h

mkIII

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

tkrolfe(at)usadatanet.net
Guest

Posted: Thu Feb 08, 2007 6:58 am Post subject: Most economical cruse speed

jimhefner wrote:  	  Quote: 	
		      	  Quote: 	
		  --> Kolb-List message posted by: "jimhefner" <hefner_jim(at)msn.com>



Terry, if you are only burning  2- 2.25 gph, you are doing better than I ever did.  I averaged around 2.75 with the 66" IVO on the FF.  Sounds like you have a good thing going, so don't change anything.  How long is your Tennessee prop?



--------

Jim Hefner

Kolbless in Tucson  

Do Not Archive



  	
 	
 

 Jim,

 

 My prop is 66" also.  Even at 2.75 gph, you were doing better than most.  Rpm has a lot to do with gph on a draggy aircraft like the FireFly.  My fuel consumption goes up dramatically when I push the rpm and airspeed to get someplace.   If I were to put a full enclosure on it and streamline struts I think it wouldn't be as big a factor.  Jack Hart is the master at that!

 

 Terry _  FireFly #95

 

 Time to get back into a Kolb!!!!!!    

 

 Do Not Archive

     [quote][b]

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