Fuel consumption.

[buck82]

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.

[Colonel Sanders]

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

[wang dang doodle]

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...

[trey kule]

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?

[floatpilot]

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.

[buck82]

Whooops! My bad Wang doodle, sorry about that. I am human after all. Have a good season yourself.

[flyinthebug]

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

x2 I was quoting my fuel burn @ 28 GPH as US gal not Imp. I agree with the 1.5 hours for front and centre each and 1 hour for rear. Thats a good rule of thumb.
PS.. I said I used 31/20 for cruise it was 31/19 not 31/20. Most of our trips were in climb phase anyways, so rarely used cruise settings (west coast in the rocks). Once you get above 5000' you can only get 31" MP anyways firewalled.

[letsfly]

The numbers I use for piston engine is HP / 20 = fuel burn per hour.
Beaver 450/20= 22.5
206 300/20 = 15
185 same as 206
180 230/20 = 11.5

Not quite as simple with the turbine. Have not yet figured out an accurite formula, but over time, maybe!

[rigpiggy]

Turbines being a different animal. A good correlation being the torque used. During the winter, when temps are cold you can hold rated torque to a higher altitude. Your torque/fuel flow/IAS will bee almost the same, as at a lower altitude, however your TAS will be higher at altitude. You will gain some efficiency due to the delta T difference, but FF will remain very similar.

[ZPC2THLgate]

Leaning will only reduce the engine life. Good way to blow jugs.






























_________________________________________________________
Zopo ZOPO ZP950+ ZOPO ZP950

[iflyforpie]

Leaning will only reduce the engine life. Good way to blow jugs.

No.

You 'blow jugs' by operating the engine outside of its parameters. Too high CHT, too high MP, too low of fuel grade, or allowing the engine to detonate.

Shoving the mixture full rich will blow jugs faster than leaving the mixture too lean when reducing power.

Also, a mixture that is too rich will foul plugs and cause exhaust valves to stick.

'Babying' your engine will introduce other problems as well. Not pulling enough MP at high RPMs can unseat the piston rings, causing blow by and increasing oil consumption. Running your engine too cool will cause piston slap, because air cooled engines have very loose clearances unless they are at their proper operating temperature.

[geodoc]

Edit ......................

An engineer friend pointed out to me once that every spark ignition piston engine burns approx. 1/2 pound per H.P. / hr.

Try it, amazingly close.

[geodoc]

Without a doubt, the best thing I have come across for the hows & whys of fuel / air mixture management for air-cooled piston aircraft engines:

http://www.avweb.com/news/pelican/182084-1.html

Read some of John Deakin's other stuff on "Pelican Perch" in AvWeb. Great stuff.

Leaning will only reduce the engine life. Good way to blow jugs.

No.

You 'blow jugs' by operating the engine outside of its parameters. Too high CHT, too high MP, too low of fuel grade, or allowing the engine to detonate.

Shoving the mixture full rich will blow jugs faster than leaving the mixture too lean when reducing power.

Also, a mixture that is too rich will foul plugs and cause exhaust valves to stick.

'Babying' your engine will introduce other problems as well. Not pulling enough MP at high RPMs can unseat the piston rings, causing blow by and increasing oil consumption. Running your engine too cool will cause piston slap, because air cooled engines have very loose clearances unless they are at their proper operating temperature.

[ruddersup?]

I think you want to say 1/2 gal per every 10 h.p.

[geodoc]

I think you want to say 1/2 gal per every 10 h.p.

oops .......................... it was getting late and skipped the proof read -

meant 1/2 a POUND per HP per hr.

[Starboardwing]

Without a doubt, the best thing I have come across for the hows & whys of fuel / air mixture management for air-cooled piston aircraft engines:

http://www.avweb.com/news/pelican/182084-1.html

Read some of John Deakin's other stuff on "Pelican Perch" in AvWeb. Great stuff.

Leaning will only reduce the engine life. Good way to blow jugs.

No.

You 'blow jugs' by operating the engine outside of its parameters. Too high CHT, too high MP, too low of fuel grade, or allowing the engine to detonate.

Shoving the mixture full rich will blow jugs faster than leaving the mixture too lean when reducing power.

Also, a mixture that is too rich will foul plugs and cause exhaust valves to stick.

'Babying' your engine will introduce other problems as well. Not pulling enough MP at high RPMs can unseat the piston rings, causing blow by and increasing oil consumption. Running your engine too cool will cause piston slap, because air cooled engines have very loose clearances unless they are at their proper operating temperature.

I have read through all of John Deakin's engine articles on AvWeb over and over and have become very curious as to how this material relates to radial engines. It seems that the history of running engines LOP actually started in the "heyday of the big radials" (as Deakin puts it) but neglects to mention the specifics about how the big old radials were actually handled. And how is the R-985 any different? I understand we don't have BMEP guages, and engine monitors in the beaver. But I have a sneaking suspicion that the fact that getting to TBO on a beaver is somewhat of an accomplishment means that something isn't right here. Shouldn't proper engine handling be rewarded by longer engine life?? is running LOP on a beaver feasible?

Pie mentions the possibility of running an engine too cool. Is this a concern in the beaver? I recall that I was always weary of CHTs hovering just over 400F, in some cases up to 420F. From what I read from Deakin, one of his remedies would be to leave MP at a higher value on TO, and to decrease RPMs. How does this technique translate to a supercharged radial engine?

Any intelligent thoughts would be greatly appreciated.

[oldncold]

dhc 2> time in tanks starting at the front fuel tank> 1hour +20 min // middle fuel tank> 1 hour+ 20 min// rear fuel tank >45min for sure, 1 hour if your technique is spot on . So to have sufficient legal vfr reserve ( day vfr 30 min) you have with all tanks filled 3 hours and 10 min of flying time. + 30 min reserve .

All that have more than a few hours in the ole beav know the back fuel tank is a water + condensation collector so don't get lax in the pre flight. The exp dhc-2 drivers I've ever met made a habit of keeping 5-7 gal in the back fuel tank, as the weather went shit have to sit down on a lake granny gas scenario.

206g models models long range 88 us gal usable block fuel burn at 20us gal /hr x 4 hours you will golden ( beside most of us have to take a pee break after 4hours anyway) less one hour and 15 min if the older model 66 gal useable

If your math isn't so good, a rule of thumb I've used over the years is , 4 gallons for every taxi n take off in a beaver and 3gal for a 206
Wish you safe and memorable season.

so a typical trip in a dhc 2 may look like this: Take 3 and gear plus some supplies for the camp to lake x 80 miles away, drop them off. Pop over to lake y 20 miles from lake x to do camp check. Then pop over to lake z 15 miles from that lake , pick up 4 guys and gear bring back to base. so they can be on the road by noon.

fuel required 4 taxi n take offs (16gal) and approx 195 miles of flying giver or take 20 miles if the outpost lakes are closer or farther on the return back to main base so 2hours 15 min if your beaver is average = 46 gal plus 16gal = 62 gal splash of grany in the rear and good to go
weight n balance on floats dhc-2 typical 1450 -1550 useful load = the 67 gal of gas =402lbs and 3 large fisherman @250lbs 1152 add you @180lbs cuz your in top shape =1332lbs leave ya enough to take some 3 flats of beer and grocery unless your beaver has the up gross to 5400 lbs mtow