J170 performance data

[giantkingsquid]

Hi all,

 

Has anyone ever seen, or perhaps made for themselves some more detailed performance charts for the J170 (or similar)?

 

The POH only has data at various engine speeds, but it's all at sea level. I'm after something like Cessna (and the other GA manufacturers do) with power (or rpm if fixed pitch) vs altitude vs speed vs fuel consumption.

 

Cheers,

 

Tom

 

 

[Roscoe]

Hi all,Has anyone ever seen, or perhaps made for themselves some more detailed performance charts for the J170 (or similar)?

 

The POH only has data at various engine speeds, but it's all at sea level. I'm after something like Cessna (and the other GA manufacturers do) with power (or rpm if fixed pitch) vs altitude vs speed vs fuel consumption.

 

Cheers,

 

Tom

Ive also asked the same question in the past........no luck

Have you asked Jabiru?

 

 

[frank marriott]

In reality, hardly worth the trouble.

 

For a J170 if you plan 15ltrs/hr, 100kts @ 2850-2900rpm the difference achieved will be less then the difference between forecast and actual wind at any alt.

 

 

[Roscoe]

In reality, hardly worth the trouble.For a J170 if you plan 15ltrs/hr, 100kts @ 2850-2900rpm the difference achieved will be less then the difference between forecast and actual wind at any alt.

I agree Frank, that's the numbers I get most of the time!

 

 

[jetjr]

Pretty sure in the POH, Jabiru correctly claim being LSA or experimental every Jabiru aircraft is different and performance varies

 

 

[giantkingsquid]

In reality, hardly worth the trouble.For a J170 if you plan 15ltrs/hr, 100kts @ 2850-2900rpm the difference achieved will be less then the difference between forecast and actual wind at any alt.

It's more the fuel than the speed. Having a flat fuel consumption figure in the POH encourages flying at low altitude, as, according to the POH there is no benefit to fuel consumption to be had from flying high. On a longer XC flight I'd much rather fly high to give an increased glide range, depending on the wind obviously. It's just semantics I suppose, but IMO the more info available the better.

 

 

[jetjr]

Maybe youre thinking about aircraft with mixture control.

 

Bing are self adjusting - sort of - and dont do much over 5000, so doubt you will see too much fuel savings at altitude

 

They are a very simple system setup to do most things, unfortunately not very well

 

 

[giantkingsquid]

Maybe youre thinking about aircraft with mixture control.Bing are self adjusting - sort of - and dont do much over 5000, so doubt you will see too much fuel savings at altitude

They are a very simple system setup to do most things, unfortunately not very well

Exactly. Given the same winds and engine rpm, at 1000 ft and 5000 ft the carburetter will be metering in less fuel at 5000 ft than at 1000 ft therefore reducing the consumption. Obviously power is reduced by this, but it will be offset to some extent by a reduction in drag. All of that data is presented in the charts I'm after.

 

It would be a fair bit of work to compile it all, so I suspect it hasn't been done by Jabiru.

 

 

[frank marriott]

Exactly. Given the same winds and engine rpm, at 1000 ft and 5000 ft the carburetter will be metering in less fuel at 5000 ft than at 1000 ft therefore reducing the consumption. Obviously power is reduced by this, but it will be offset to some extent by a reduction in drag. All of that data is presented in the charts I'm after.It would be a fair bit of work to compile it all, so I suspect it hasn't been done by Jabiru.

With an 80hp (auto lean) engine you have got to be kidding. Any small difference would not effectively change your endurance so becomes academic & of no use in real terms.

Just enjoy your flying in a light aircraft without over complicating things for no real gain - IMO keep things simple when nothing gained by making extra calculations.

 

 

[Bruce Tuncks]

I was really impressed with the wind feature now on ozrunways. Flying from Condobolin to Narromine into a 20 knot wind, the app said how the wind lessened over 5000ft.

 

It was exactly right, and it paid to climb to 6000 ft to benefit. I would not have gone so high on a leg like this normally.