Fuel consumption.

This forum has been developed to discuss Bush Flying & Specialty Air Service topics.

Moderators: ahramin, sky's the limit, sepia, Sulako, North Shore, Rudder Bug

Message
Author
cbrn
Rank 0
Rank 0
Posts: 4
Joined: Wed Dec 03, 2008 11:41 am

Fuel consumption.

#1 Post by cbrn » Mon Mar 26, 2012 5:09 pm

Hi,

I need some info here.
What is the fuel consumption you get on the DHC-2 and on the C-206 on floats?

If you have the figures also for the take off run, climb and taxi will be greatly appreciated.

Thx!

cbrn
---------- ADS -----------

Slats
Rank 6
Rank 6
Posts: 457
Joined: Sun Feb 04, 2007 7:35 pm

Re: Fuel consumption.

#2 Post by Slats » Mon Mar 26, 2012 7:17 pm

Same as on wheels really.
206 with a 520: 15 gph
206 with a 550: 17 gph
DHC-2: around 20 gph if I recall correctly
---------- ADS -----------

User avatar
Cat Driver
Top Poster
Top Poster
Posts: 18818
Joined: Sun Feb 15, 2004 8:31 pm

Re: Fuel consumption.

#3 Post by Cat Driver » Mon Mar 26, 2012 7:26 pm

Why would you need to know the fuel burn on the take off run? :rolleyes:
---------- ADS -----------

User avatar
Colonel Sanders
Top Poster
Top Poster
Posts: 7529
Joined: Sun Jun 14, 2009 5:17 pm
Location: Over Macho Grande

Re: Fuel consumption.

#4 Post by Colonel Sanders » Mon Mar 26, 2012 8:00 pm

Every CPL should know this rule of thumb:

To estimate your fuel burn at WOT at takeoff, drop a zero off your horsepower.

Seriously. 200hp, 20 gph at WOT. 300hp, 30 gph at WOT.

You probably cruise at 65% power. Without leaning very well,
take 2/3 of the above WOT fuel burn.

For example, 300hp takeoff burn is 30 gph, cruise 20 gph.

Obviously if you pull the throttle (and the mixture) back, you can
do better. But the above rule of thumb gets you in the ballpark.

See BSFC if you care to learn more.
---------- ADS -----------

rapid602
Rank 4
Rank 4
Posts: 203
Joined: Wed Dec 01, 2010 5:28 pm

Re: Fuel consumption.

#5 Post by rapid602 » Mon Mar 26, 2012 8:07 pm

Thanks for that Colonel. GREAT STUFF !!!

I have been away from flying for a while, and most of my flying was turbines.

But

Thanks .... great to know.
---------- ADS -----------

User avatar
Colonel Sanders
Top Poster
Top Poster
Posts: 7529
Joined: Sun Jun 14, 2009 5:17 pm
Location: Over Macho Grande

Re: Fuel consumption.

#6 Post by Colonel Sanders » Mon Mar 26, 2012 8:15 pm

You're welcome!

As an example, sometimes I fly a Beech 18, which has 450hp
R-985's on each side.

So, as a rule of thumb, 45 gph per side (90 gph total) on takeoff,
and 2/3 of 90 (65% power) is 60 gph in cruise, at say 30 inches
and 20 turns. Call it a gallon a minute in cruise. You can tell I'm
not buying the 100LL!

I fly so many different types of aircraft, these sorts of calculations
come in handy.
---------- ADS -----------

wang dang doodle
Rank 0
Rank 0
Posts: 13
Joined: Fri Jul 30, 2010 11:28 am

Re: Fuel consumption.

#7 Post by wang dang doodle » Mon Mar 26, 2012 8:24 pm

in a 206 try thinking a liter per minute....makes it simple....a 40 min flight= 40 liters.


in a beaver 20-22 gal per hour.. for simplicity call it 90 liters an hour =1.5 liters per min...so a 30 min.flight...you need 45 liters since most fuel tanks read in liters. And don't forget that little extra bit for your kids that are waiting for you to come home..
---------- ADS -----------

User avatar
Cat Driver
Top Poster
Top Poster
Posts: 18818
Joined: Sun Feb 15, 2004 8:31 pm

Re: Fuel consumption.

#8 Post by Cat Driver » Mon Mar 26, 2012 8:31 pm

That is a pretty safe method to use colonel, for sure it is ball park.

Over the thousands of hours I flew long interconental ferry flights with the P&W R1830's I could take it to the bank my average fuel burn would be 72 GPH for the trip.

The longest trip I ever did non stop was 19 hours and ten minutes.......

We were real serious about our fuel burn on that one and got a lower over all fuel burn.
---------- ADS -----------

User avatar
Cat Driver
Top Poster
Top Poster
Posts: 18818
Joined: Sun Feb 15, 2004 8:31 pm

Re: Fuel consumption.

#9 Post by Cat Driver » Mon Mar 26, 2012 8:38 pm

Aaaaaaahhhhh, the what measurement should we use when planning any flight conversation.......be careful....real careful when converting from one measurement to another....it can be a real gotcha.

For instance coming back to the Socialist Republic of Canada I have to be careful thinking of take off and landing visilibities......I'm so used to meters your miles and feet confuse me.
---------- ADS -----------

User avatar
Lost Lake
Rank (9)
Rank (9)
Posts: 1114
Joined: Wed Mar 19, 2008 5:11 am
Location: On top

Re: Fuel consumption.

#10 Post by Lost Lake » Tue Mar 27, 2012 8:26 am

Colonel Sanders wrote:You're welcome!

As an example, sometimes I fly a Beech 18, which has 450hp
R-985's on each side.

So, as a rule of thumb, 45 gph per side (90 gph total) on takeoff,
and 2/3 of 90 (65% power) is 60 gph in cruise, at say 30 inches
and 20 turns. Call it a gallon a minute in cruise. You can tell I'm
not buying the 100LL!

I fly so many different types of aircraft, these sorts of calculations
come in handy.
Are you saying that the beach burns 50% more fuel per side than a beaver? What is the reason for that?
---------- ADS -----------

User avatar
Colonel Sanders
Top Poster
Top Poster
Posts: 7529
Joined: Sun Jun 14, 2009 5:17 pm
Location: Over Macho Grande

Re: Fuel consumption.

#11 Post by Colonel Sanders » Tue Mar 27, 2012 11:57 am

the beach burns 50% more fuel per side than a beaver? What is the reason for that?
How the guy in the left seat positions the levers in the engine control quadrant!

The Beaver burning 20 gph is not running 30/20.
---------- ADS -----------

flyinthebug
Rank (9)
Rank (9)
Posts: 1674
Joined: Wed Feb 18, 2004 8:36 am
Location: CYPA

Re: Fuel consumption.

#12 Post by flyinthebug » Tue Mar 27, 2012 12:36 pm

Colonel Sanders wrote:
the beach burns 50% more fuel per side than a beaver? What is the reason for that?
How the guy in the left seat positions the levers in the engine control quadrant!

The Beaver burning 20 gph is not running 30/20.
I gotta agree with you Colonel. I used to plan around 28 GPH on the DHC2. We ran 31/20, and rarely leaned below 4000'.
---------- ADS -----------

User avatar
Colonel Sanders
Top Poster
Top Poster
Posts: 7529
Joined: Sun Jun 14, 2009 5:17 pm
Location: Over Macho Grande

Re: Fuel consumption.

#13 Post by Colonel Sanders » Tue Mar 27, 2012 12:49 pm

Fuel burn is determined by horsepower produced (power setting) and mixture setting - BSFC.

For comparison, I also fly a Stearman with an R-985, 450hp. I NEVER cruise at high power settings because with all that junk hung out in the breeze, all you're doing is shuffling air around.

In the Stearman I like 25 inches - no more - and 18 or even 17 turns.

The lowest possible RPM without exceeding your max allowable BMEP will yield the lowest gph for the same horsepower.
---------- ADS -----------

User avatar
Lost Lake
Rank (9)
Rank (9)
Posts: 1114
Joined: Wed Mar 19, 2008 5:11 am
Location: On top

Re: Fuel consumption.

#14 Post by Lost Lake » Tue Mar 27, 2012 4:22 pm

flyinthebug wrote:
Colonel Sanders wrote:
the beach burns 50% more fuel per side than a beaver? What is the reason for that?
How the guy in the left seat positions the levers in the engine control quadrant!

The Beaver burning 20 gph is not running 30/20.
I gotta agree with you Colonel. I used to plan around 28 GPH on the DHC2. We ran 31/20, and rarely leaned below 4000'.

Wow, those are high setting IMHO. I used to run 28/18 in Northern Ont, 29/19 in the arctic. Why would you use those settings uless you are at high altitude, which would require leaning? In the arctic, 29/19 yeilded a legit 20 gph. We also leaned , even though at sea level. Company SOP. Fuel cost was a definite factor.
---------- ADS -----------

rigpiggy
Rank 10
Rank 10
Posts: 2171
Joined: Sun Jan 16, 2005 7:17 pm
Location: west to east and west again

Re: Fuel consumption.

#15 Post by rigpiggy » Wed Mar 28, 2012 4:31 am

wang dang doodle wrote:in a 206 try thinking a liter per minute....makes it simple....a 40 min flight= 40 liters.

.you need 45 liters since most fuel tanks read in liters.


Maybe as a check when buying the fuel. I don't think I have ever flown an aircraft that had litres on the guages. Pounds, imp Gals, or Gals
---------- ADS -----------

zeppelin
Rank 2
Rank 2
Posts: 52
Joined: Sun Dec 23, 2007 10:10 pm

Re: Fuel consumption.

#16 Post by zeppelin » Wed Mar 28, 2012 7:08 am

of course the guages aren't in liters,Cessna's are built in the States where they can't even spell "leetur."I don't trust the guages anyway,and for all my 206 time they were actually taped with electric tape over them.And since all the fuel tanks/pumps in Canada are in "leeturs",why not think in liters...still 30 liters =30 min.You don't have to do a conversion,and better yet,the brand new CPL dock guy does'nt have to do a conversion when he fuels you...Simple...just trying to help...Or you could goto the fuel guy and say..I need a half hour fuel...let's see that's 15 gall per hour divided by 2 = 7.5 gall,but the pump is in liters so let's see 7.5 gall times about 4.5=30. so I need 30 liters please....I'm not trying to be a smart ass here but .. DUHH....And it took me years to figure what a liter was,cause I'm of the Gallons age....I'd better add make sure you have your reserve before I get pounced on for not mentioning it..
---------- ADS -----------

User avatar
Lost Lake
Rank (9)
Rank (9)
Posts: 1114
Joined: Wed Mar 19, 2008 5:11 am
Location: On top

Re: Fuel consumption.

#17 Post by Lost Lake » Wed Mar 28, 2012 8:58 am

Turbines are simpler, but you could use the same formula. Simply multiply the # of pounds required X 6 = leetours required.
Pt27 -6 burns 300 lb/hr= 180 leetours/hr. Of course that's at 1 gal= 7 lb.
---------- ADS -----------

rapid602
Rank 4
Rank 4
Posts: 203
Joined: Wed Dec 01, 2010 5:28 pm

Re: Fuel consumption.

#18 Post by rapid602 » Wed Mar 28, 2012 12:11 pm

Lost Lake Question for you !!!

Those fuel burn numbers are they for a specific cruise altitude. say below 10,000 ft.

Reason I flew a Turbine usually around 210, 220, 230, and we used 600 pph hour #1, 400 pph hours #2,3,4 example long Xcountry's
---------- ADS -----------

User avatar
Lost Lake
Rank (9)
Rank (9)
Posts: 1114
Joined: Wed Mar 19, 2008 5:11 am
Location: On top

Re: Fuel consumption.

#19 Post by Lost Lake » Wed Mar 28, 2012 8:27 pm

Sea level
---------- ADS -----------

Slats
Rank 6
Rank 6
Posts: 457
Joined: Sun Feb 04, 2007 7:35 pm

Re: Fuel consumption.

#20 Post by Slats » Wed Mar 28, 2012 10:43 pm

Sadly, it has been a couple years since my last trip in a piston beaver and so I don't recall the exact tank capacities, but it seems to me that some wildly high numbers are being tossed around here. I do recall ballparking that I could count on full bellies for around 4 hours of endurance depending on how horrific the combination of load+canoe+OAT+highest mountain ridge was on that particular day, even with deploying standard Beaver tricks of cracking some cruise flap and running 29/19 or 30/20. I DO know for sure though that if I had been burning 8 gph (20 vs 28!?!?) more than I had planned I surely would have ingloriously run out of fuel more than once. I also do recall quite confidently that leaning a Cessna 185 or 206 by the book will certainly not yield 20 gph in cruise, even with the 550 as opposed to the 520. Your average altitude of 3-5000' will get you roughly 15 gph and 17 gph for the 520 and 550 respectively, and you can do considerably better than even those numbers if the circumstances warrant going up high. Oh, and for what it is worth: never once experienced ANY issues or problems related to engine mismanagement-no cracked jugs, no nothing-ever. It's something I still take great pride in.

Or maybe all my memories of my first few thousand hours are all askew.
---------- ADS -----------

buck82
Rank 4
Rank 4
Posts: 234
Joined: Tue May 03, 2005 7:29 pm

Re: Fuel consumption.

#21 Post by buck82 » Wed Mar 28, 2012 11:07 pm

Keep in mind most Beavers, and the POH, indicate fuel burn in imperial gallons. 20 Imp is not 90 litres/hr. If you are burning significantly over 20 Imp an hour while using 28/18 or 29/19 you should mention it to your mechanic. Very likely there is something else not right with the engine and carb set up, for example a bad float in the carb, mixture too rich, worn supercharger, bad cylinders/dead cylinders, mag timing off.. one or both. When tuned and leaned properly, the 985 on a beaver with floats should be giving you an honest 20 Imps/hr. Any time it wasn't there was something else wrong with it... or the tanks were leaking.
---------- ADS -----------

User avatar
Colonel Sanders
Top Poster
Top Poster
Posts: 7529
Joined: Sun Jun 14, 2009 5:17 pm
Location: Over Macho Grande

Re: Fuel consumption.

#22 Post by Colonel Sanders » Thu Mar 29, 2012 5:01 am

All my numbers are in US gallons, which is what my fuel totalizers indicate.
---------- ADS -----------

wang dang doodle
Rank 0
Rank 0
Posts: 13
Joined: Fri Jul 30, 2010 11:28 am

Re: Fuel consumption.

#23 Post by wang dang doodle » Thu Mar 29, 2012 5:38 am

I stand corrected Buck 82. you are right..20 imp actually is 90.92 liters not 90.........How friggin silly of me...It's really really easy thinking like this... 1.5 liters per min. 10 min =15 L 18 min=27L and so on..... but I will admit,in a beaver ,I usually ask for front and 10 or front and 20...just because of the gauge set up... you can just read the gauge for when it reads 10 or whatever...but in a Cessna...I'm in the 1 liter a min. thought..You DON"T have to agree with me but it's never failed me...Have a good season...
---------- ADS -----------

trey kule
Rank 11
Rank 11
Posts: 4214
Joined: Fri Aug 19, 2005 7:09 pm

Re: Fuel consumption.

#24 Post by trey kule » Thu Mar 29, 2012 6:07 am

Slats, I am in 100% agreeement with your numbers on the Beaver. Never met a pilot who actually flew one who figured out the fuel burn based on a formula. or worried to much about how much fuel a takeoff would use, unless they were doing multiple short hops on a tank...a simple number that depended on how long you had to warm up the engine on the start was usually enough.
I knew lots and lots of pilots who never had a fuel issue and could tell you to the minute how much fuel they had on board.
So much for common sense and experience. BTW...Barrels of fuel put on with a hand pump are not calibrated at all...You fill the tanks as needed... and anyone who thinks "gramma" fuel has no weight has never really worked a beaver very much. A typical beaver pilot will calculate their fuel something like this.....gotta fly to fish smell pond......strong headwind...lets see...45 mins there, 30 back...front and center tanks should do it (reserve included). Ask them how many liters they burn per hours and they will look at you with the deer in the headlight stare. Ask them how much time they can fly on the front (or center , or rear) tank with two take offs on a cold fall morning, and they will tell you to the minute....

Now to the original poster.....before you fly the plane ask the last person who flew it and knows it.
If not, the book figure of 20 imp, 25 US will work. Add 5 gal (US) for your iniital start, warm up, taxi and takeoff, unless it is very cold or you need to taxi a long way. You have about 10-15 gal for reserve so your calculations should not be that far off. Fill the tanks as required and do some math until you get the typical fuel burn (in time per tank) into your brain.

If I may ask, what prompted your initial question?
---------- ADS -----------

floatpilot
Rank 3
Rank 3
Posts: 118
Joined: Tue Jan 11, 2011 8:18 am

Re: Fuel consumption.

#25 Post by floatpilot » Thu Mar 29, 2012 6:53 am

In 13 years of bush flying I can honestly say that i've never done a fuel calculation as per "the numbers". Beaver always full front and ten or so in the middle for short trips(always keep some gas in the other tank, incase something goes wrong with the front) full front and middle for longer trips or short trips with lots t/o. Long trips full everything! An old guy once told me that if you are worried about the "extra wieght" of gas in a beaver, you shouldn't be flying one!
The front and middle will give you about 1.5hrs and the back about1hr no leaning with 30/20 for climb and 28/1850.
Like somone eles said don't but too much trust in fuel gauges, keep track of time. The beavers we fly you can plan for front and middle to give you 1.5 each and back 1hr without leaning.
For cessna we use a simple system of a stick with grooves cut into it in inches. 1 inch is about 10 gals. Never lies.
---------- ADS -----------

Post Reply

Return to “Bush Flying & Specialty Air Service”