Trike 912 Fuel Consumption

[Tracktop]

Hi

 

XC soon ( I hope) so -

 

What fuel consumption are you getting from your 912

 

What figures do you use to when planning a trip?

 

Do you find it varies much between circuits and a trip?

 

I did 1 hr of circuits this morning with 17 Touch and goes ( slowing to about 20kts), circuit height 800ft and used about 7.5 lts / hr

 

I have been finding a combination of circuits ( maybe 30 min) and local flying ( maybe 60min) it always seems to be << than 10 lts / hr one up ( but usually with a full tank 70lt).

 

Do you find a passenger changes the consumption much?

 

My guess to start with would be to use 10 or 11 lt / hr as a good planning figure?

 

No doubt my CFI will have and provide his requirements when the time comes :big_grin:

 

 

[eastmeg2]

Hi Ray,

 

Having a passenger does tend to add about 2 litres per hour to fuel consumption.

 

The speed you intend to fly at has a much larger effect.

 

Assuming you intend to fly at the usual 56kts you should get 10L/hr solo and 12L/hr with a passenger. Those fat tyres might add 0.1 L/hr too.

 

In the extremes, I've had 8L/hr flying solo at 43kts in company of Wizard winged Edge-X's close to sea level and I've had 14 to 15 L/hr flying 2 up at 65kts at 5000ft.

 

Cheers,

 

Glen

 

 

[Guest Maj Millard]

I'm assuming you are talking about the 80hp here ?. I couldn't see you getting those figures with a 912ULS. A nicly loosened up 80hp engine will generally see 11-12 Lts per hour on average. I ferried an early Storch once (ragwing), with an 80 Hp, and I averaged 9 LPH for the whole trip!., and that was with a 10 kt headwind most of the way !. They do get pretty good consumption figures really.

 

The 912ULS (100hp) on the other hand, generally yeilds anywhere between 15-20 Lts per hour depending on what type aircraft it's in. Average for a long trip is ofter around 16-16.5 Lph unless you push it a bit, then you'll see 18-20 easily.

 

Most 912 engines will take a good 50-60 hours from new to really start loosening up, until then fuel figures are generally higher. My 912ULS in the Lightwing has just turned 400 hrs and is getting really nice now.......................................................................................

 

 

[Tracktop]

Thanks Glen

 

Going to have to go for another fly (Oh bugger ) and see how my cruise consumption is then.

 

Probably need some sort of accurate measure as well I suppose as a jerry can hold anywhere between 20 and 25lt and I just can't resist squeezing those last couple of lts in

 

Today I was climbing out at trim ( wing trimmed fast 56kts?) then fast downwind (approx 65-75kts true air speed)

 

 

[Tracktop]

Most 912 engines will take a good 50-60 hours from new to really start loosening up, until then fuel figures are generally higher. My 912ULS in the Lightwing has just turned 400 hrs and is getting really nice now.......................................................................................

Yes it is the 80hp

 

Now has 50hrs on and consumption does seem to be improving, but then I am only flying one up with a mix of local flights and circuits, till I get Pass X, and earlier it was all 2 up and circuits. I don't ever recall it being worse than 10 or 11lt/hr both on the fuel burn meter or on the refill guesstimation.

 

 

[Kev]

Ray,

 

On my 912S since new I have averaged less than 9.5 lt/hr - that's two-up and average trimmed at 60kts. Drag counts.

 

Fly safely

 

Kev

 

 

[Guest Qwerty]

Major,

 

The 10 kn headwind shouldn't knock the fuel consumption around too much, not as bad a 25 kn headwind. If you got 9 l/hr with a 10 kn headwind, I think that works out to 12.5 l/hr with a 25 kn headwind, Have I done the sums correct??

 

Qwerty:ne_nau::peepwall:

 

 

[slartibartfast]

At the risk of appearing ignorant/stupid, how does a headwind change your fuel burn per hour?

 

The plane/trike doesn't know there is a headwind.

 

Certainly you'll use more fuel for the trip, but per hour?

 

 

[Guest Qwerty]

Mr Bartfast, I'm paraphrasing here, "It was supposed to be sarcasm, I'm afraid that I'm not very good at it really."

 

 

[skeptic36]

Probably need some sort of accurate measure as well I suppose as a jerry can hold anywhere between 20 and 25lt and I just can't resist squeezing those last couple of lts in

Hi Ray,

 

If you have an accurate set of scales you can easily determine how much fuel you have added to refill ( a litre of petrol weighs approx .72kg).

 

Regards Bill

 

 

[Tracktop]

Major, The 10 kn headwind shouldn't knock the fuel consumption around too much, not as bad a 25 kn headwind. If you got 9 l/hr with a 10 kn headwind, I think that works out to 12.5 l/hr with a 25 kn headwind, Have I done the sums correct??

 

Qwerty:ne_nau::peepwall:

Hi

Yes a head wind will make a big difference 10kts wind = approx 20% of 56Kts

 

so I would expect ~ 20% difference in consumption BUT

 

Just to clear up a bit

 

My climb out / down wind speed difference was true air speed. So wind was not a factor

 

The difference was operator generated by pulling back on the bar ( requires effort as opposed to trim where there is no bar pressure) and increasing power ( thus using more fuel)

 

so

 

normal trim speed as Glen quoted 56kts, no bar pressure and about 4000 RPM for level flight.

 

Climb out at trim - one up (- reduced power as full power is too much one up- possible exceed angle of attack if hit by a gust ( I think)) 5000RPM

 

Climb out at trim 2 up = full power ~ 5500RPM

 

Level Cruise not at trim - Control Bar back - 4000 -> 5000RPM = increase speed to 56 -> ~80kts

 

Similarly Bar forward ( also requires effort) not at trim 3500RPM = decrease speed from trim = maybe 45kts

 

 

[Tracktop]

Good thinking Bill, I can do that :big_grin:

 

 

[Guest Qwerty]

Crap......my sense of humor just dosen't work here.

 

Head wind makes no difference to fuel consumption as discussed here, ie, l/hr.

 

 

[Tracktop]

Does when I read it properly instead of jumping in:faint:

 

 

[slartibartfast]

Mr Bartfast, I'm paraphrasing here, "It was supposed to be sarcasm, I'm afraid that I'm not very good at it really."

Whoa - that was subtle.

 

We need a sarcasm icon. I keep running afoul of that one too.

 

 

[Guest Qwerty]

I am afraid that if I keep this up I may be late.

 

 

[slartibartfast]

As in the late Qwerty?

 

 

[Guest Qwerty]

The mere prospect of the thought of the idea hadn't speculated at crossing my mind.

 

 

[Tracktop]

 

 

[bones]

I'm assuming you are talking about the 80hp here ?. I couldn't see you getting those figures with a 912ULS. A nicly loosened up 80hp engine will generally see 11-12 Lts per hour on average. I ferried an early Storch once (ragwing), with an 80 Hp, and I averaged 9 LPH for the whole trip!., and that was with a 10 kt headwind most of the way !. They do get pretty good consumption figures really.The 912ULS (100hp) on the other hand, generally yeilds anywhere between 15-20 Lts per hour depending on what type aircraft it's in. Average for a long trip is ofter around 16-16.5 Lph unless you push it a bit, then you'll see 18-20 easily.

Most 912 engines will take a good 50-60 hours from new to really start loosening up, until then fuel figures are generally higher. My 912ULS in the Lightwing has just turned 400 hrs and is getting really nice now.......................................................................................

My 912ULS just ticked over 1100hrs and still gets the same as when i got it 1000hrs ago, on average pushing a gyro(high drag) about 5100 rpm, at about 70kts, over 7 hrs it averages 15-16lts, but i have got as low as 8lts over 6hrs, very good conditions(not at that speed thou)

 

 

[Guest Maj Millard]

In respect to a headwind costing you in fuel consumption. If you are ferrying, and need to get somewhere before the sun sets, you will have a particular ground speed that you wish/need to maintain. Therefore, if the headwind causes you to drop below that ground speed, you are going to crank in another one or two hundred RPMs to keep the ground speed up where you want it....that, my friends, costs fuel..........Now, one smart fellow may say, start earlier, and allow more time for potential forecasted or unforcasted headwinds. However if it's the third state you've flown in that day, and your forth leg for the day, you will get caught, it's just the law of averages...............................................................

 

 

[alf jessup]

I guess it all relates in the end to where your foot or hand throttle is set and how well tuned your engine is.

 

If you want to fly fast you use more power which = more drag which = more fuel. but in a headwind could relate to using less in the end as you spend less time to get there.

 

My 912 in the trike uses around 22 +- lph full noise (5500rpm)climbing out, cruise hands off (4250 rpm) depending on the density/humidity/temp about 9 lph, wind the trim full on and 3800/3900 rpm straight and level between 6 and 7 lph. but the ground goes past slower

 

She is well run in 650 hrs, mind you balanced carbies make a difference too with creating efficency in the engine.

 

My 2 cents worth

 

Cheers

 

Alf

 

 

[Tracktop]

Thanks Alf - probably in line with my guesses

 

OK here is another component to consider

 

Does a high windscreen increase or decrease consumption (drag). OR no net effect

 

I agree it effects air speed indication

 

And now I written and thought about that, raises another one is an outback more or less efficient than a pod? - probably hard to answer

 

 

[Kev]

Ray,

 

If you plan to do the weighing fuel thing, be aware that most bathroom type scales are totally inaccurate at the low end of the scale ie empty fuel can.

 

To accurately weigh an empty can (especially the plastic ones), get on the scales first and weigh yourself, then do it again whilst holding the can.

 

Safe Flying

 

Kev

 

 

[alf jessup]

Thanks Alf - probably in line with my guessesOK here is another component to consider

 

Does a high windscreen increase or decrease consumption (drag). OR no net effect

 

I agree it effects air speed indication

 

And now I written and thought about that, raises another one is an outback more or less efficient than a pod? - probably hard to answer

Ray,

 

Cant really say with authority that a tall screen reduces consumption but I can say it makes flying far more comfortable and if it did it would only be Marginal if any.

 

Yes it does effect the indicated airspeed by a few knots (well it has mine).

 

I would say an out back with a streak 3 wing would probably use more fuel than a podded one with a streak 3 wing at the same indicated airspeed due to the drag associated with all the bits and pieces out in the airstream but again I think it would be hardly noticeable except maybe at the fuel pump if you both had full fuel and pretty much used the same power settings at take off, cruise maybe a different power setting to attain the same ias??? this would effect fuel burn between both of them?? dont know.

 

There are too many maybe,s in this as even though the Rotax 912 engines are made by the same manufacturer some perform differently than others from new same as the wings made for airborne.

 

That's my view on this

 

Alf