Fuel Burn - J160

[BigPete]

OK Guys (and Girls if there are any flying a Jabiru?)

 

This is aimed at you who have a "Fuel Mizer" gauge or similar.

 

What is your favourite cruise speed at what RPM and what is your comsumption in litres per hour?

 

How about readings at:

 

2400 RPM

 

2500 RPM

 

2600 RPM

 

2700 RPM

 

2800 RPM

 

2900 RPM

 

3000 RPM

 

3100 RPM

 

I quite often cruise at around 2800 RPM as it sounds and feels quite relaxed. This gives me around 92 knots.

 

Am I being too easy on the motor - should I cruise at 2900 or 3000?

 

What are your thoughts?

 

regards

 

 

[tomcat]

Big Pete l fly at 2800rpm and the plane runs very smoothly. All gauges are in the green also l use around 13 to 14 liters per hour. Isn't the game to fly the most economical and furtherest distance as possible for your dollar?

 

 

[BigPete]

Ah - Tomcat - thankyou for your reply.

 

Tocumwal is very close - we should meet up one day.....

 

I kbow I get around 14 liters an hour when I cruise at 2800 rpm. This gives me an IAS of around 92/93 knots.

 

I woiuld like to know what I can expect at 3100rpm and around 100 knots cruise? Does the jabb really start o use the juice once past 2900/3000 rpm?

 

regards

 

 

[Yenn]

A friend of mine with a J230 advises that his 3.3l engine gives 117 or 118kts cruise at 2800r.p.m. for 20 to 21 l /hr.

 

2600r.p.m. gives 105 kts and 16 l/hr.

 

For precautionary search he uses 1 stage of flap, 2000r.p.m and 70 kts.

 

This plane glides at a very good rate, but he says it is hard to land because it floats in the least gust of wind. I believe he uses 55 kts over the numbers when landing to get a short roll.

 

 

[Geoff]

Hi Pete just got back from our big trip up north and hear are the fuel figs

 

4700nm app 773.38 lt used for 56.9 eng hours = 13.59 lt pr hour rpms 2850- 2900

 

 

[theoy]

Hi Pete

 

My Jabiru J160C with a 60x42 inch propeller burns about at 2800 rpm = 14L/hr, 2900 rpm = 15L/hr and it gets thirsty and costly at 3000 rpm = about 18L/hr. IAS ranges 100 - 110 knots depends on all up weight, most times I cruise at 105 knots.

 

cheers

 

Theo

 

 

[BigPete]

Thanks guys for all the info.

 

I see in the latest AOPA magazine that Rod Stiff Quotes as saying the new J170c will do 100 knots at 2850 rpm!

 

Mind you - that could be with a 70kg pilot and 20 litres in the tanks???

 

Does that bigger wing alow more power to convert to forward speed???

 

Is anyone contemplating putting the wider wings on their 160 and getting an extra 60kg legal payload?? (J170c LSA 600kg class)

 

regards

 

 

[Geoff]

Pete once a plane has been rego at 540 you can't change it.

 

 

[BigPete]

Arrrrgghhhh

 

regards

 

 

[Guest brentc]

Don't worry Peter, the laws of aerodynamics tell me that it is impossible for the J170 to go faster with 5 foot of extra wing and two big wing-tips! Same goes for the J200 vs J230.

 

That figure is likely based on TRUE airspeed in ideal conditions with a midget at the helm and fuel vapours!

 

You will get a better climb with the longer wing however will suffer in speed. I would expect around 5 knots difference and you'll probably find that they were quoting around 105 - 110 for the 160 at the same rpm.

 

 

[Guest J430]

Brent is on the money.

 

longer wing is about 5kys slower.

 

Warning

 

Stop penny pinching you lot!!!

 

4 cyl should be run at 14-15 LPH and the 6cyl about 22-24LPH ........any less and its possibly too lean:crying:

 

The UL 4 cyl tyically gets a TAS at 100kts at 14LPH.

 

I would also suggest you have the tacho calibrated, mine was over reading by 200 rpm at 2600-2800 out of the box. They are a digital to analogue device and can be out a bit so you need to read the calibration procedure and set it up right.

 

Dont baby your engine!

 

J;)

 

 

[Modest Pilot]

Oils ai'nt Oils

 

Ai,nt necessarily so. Depends on a lot of factors.

 

Three of us went Gatton to Caboolture the other day.

 

The J400 with 86sq ft of wing as slower than the J250 with 120 sq ft of wing, similar weights and 2800 rpm. I was dead last in the Sonex by 2 minutes!

 

Same wing sections on the Jabs I believe (4412) maybe better aspect ratio or lower angle of attack.

 

 

[Guest brentc]

As J430 says, probably taco related or otherwise prop. The props vary significantly out of the box. Last week a mate swapped my old timber 6 cylinder 2-blade with his (on his 6 cylinder SP) which is a year newer than mine and he got 7 knots more. Now he wants to buy it off me. Problem is that if I ever buy a new timber one it probably won't go as fast as my old one.

 

More wing equals more drag and lesser cruise in every instance from what I've seen.

 

J430 got very excited when I took him for a ride in my J400 and hit 140+ knots. At that speed his winglets would peel off!

 

 

[Guest J430]

Not sure about that but yes there is a difference.

 

John, the J400 you flew back from gatton actually was a J430:blush: and is the 100 sq. foot wing. Tell a little story here now, your old QF mat CM flew it the other day after I remove the wheel spats and the socks on the legs, he confirmed my observation that we had picked up 3-4 knots (unreal I know but true) and we now have the 285 jet not the leaner 278 jet that was fitted in the very early days of the leaner jets. We now burn around 22-23 LPH instead of 20LPH and we get a bit more grunt and a bit more speed, maybe 1-2 knots for the extra fuel and 1-2 for the spats, I dont know which but it was very surprising.

 

I do know that some folk run around off the step and run too lean, and they might have also contributed to the attempt by jabiru to richen up not just due to any induction leaks or other things.

 

In your case its not so easy to say, the 4 cyl fuel burn I quoted was for teh jabiru UL, there are a few at YCAB and this is the consistent consensus of them. probably applies to the fatter J160/170 also.

 

On your sexy little Sonnex it might be a bit different, and the different carby you have too. Its all interesting stuff! Loved your plane!

 

Cheers

 

J;)

 

PS CM said to say gooday!