MPG Widget

[N941WR]

Asking for a friend ...

Is there a widget in the SV system that can display the MPG based on groundspeed, not AS or TAS?

I couldn't find one in the manual but it would be kind of cool to see it displayed.

Thanks!

 

[RV8JD]

From page 5-9 of the SkyView Classic/Touch Pilot's User Guide - Rev AD:

"The Fuel Efficiency info item (displayed as NM/GAL) displays how efficiently the aircraft is using fuel with respect to the speed it is traveling over the ground (this also can be displayed as MI/GAL, KT/GAL, KM/LTR)."

 

[N941WR]

From page 5-9 of the SkyView Classic/Touch Pilot's User Guide - Rev AD:

"The Fuel Efficiency info item (displayed as NM/GAL) displays how efficiently the aircraft is using fuel with respect to the speed it is traveling over the ground (this also can be displayed as MI/GAL, KT/GAL, KM/LTR)."

Thanks, I thought it was there but missed in the manual.

 

[hoyden]

I would like for the value to be saved to the log file. It would help visualize engine performance for various mixture settings.

 

[swatson999]

I would like for the value to be saved to the log file. It would help visualize engine performance for various mixture settings.

It is. You just have to compute it.

mi/gal = (mi/hr)/(gal/hr)

 

[Marc_J._Zeitlin]

I would like for the value to be saved to the log file. It would help visualize engine performance for various mixture settings.

Actually, if you're trying to figure out engine performance, TAS/GPH is a far more useful determinant, as it's not affected by wind - it's JUST a function of the aircraft's performance.

 

[hoyden]

It is. You just have to compute it.

Computing is nice but graphing the result in Saavy analysis would be nicer. I had not thought of TAS/GPH so maybe I'll have to dust off Excel and plot a few. I typically see 20+ nm/gal flying my IO-360 CS RV-6 at 20" and 2000 rpm. TAS typically 100 kts with FF 4.2-5.0 gph.

 

[airguy]

As mentioned, this is a groundspeed referenced number, but still handy to have in flight. See my bottom right corner. The range you see there is not incorrect, I have long range tanks with 68 total gallons on my RV-9A.

 

[swatson999]

Just for fun, I just added a column to a copy of the data file, named it Fuel Eff, and filled it with TAS/FF, then loaded it into Savvy. Works fine!

What I think you really want is for Savvy to add the ability to compute additional fields, rather than add things that can be computed on the ground to the Dynon output stream (we call these, appropriately enough, "Ground-derived data channels" at work). That way, you could compute and display all sorts of your own favorite things.

I'll put in a request to Savvy, and anyone else thinking this would be interesting/fun should do likewise. Maybe they'll add this capability to a later release!

 

[Rhino]

As mentioned, this is a groundspeed referenced number, but still handy to have in flight. See my bottom right corner. The range you see there is not incorrect, I have long range tanks with 68 total gallons on my RV-9A.

Showed that picture to a non-aviator friend and he almost expelled his coffee through his nose. We forget sometimes how complicated all this seems to non-aviation folks.

Yeah, I know. I'm off topic.

 

[hoyden]

What I think you really want is for Savvy to add the ability to compute additional fields, rather than add things that can be computed on the ground to the Dynon output stream (we call these, appropriately enough,

I'll try adding a TAS/FF column and uploading to Savvy. I think this info would be especially useful when choosing the best power setting when tussling with a headwind.

 

[swatson999]

Isn't the max MPG simply Best Economy mixture, which is peak EGT?

 

[N941WR]

Thank you all for your input. My friend has been watching this thread and is going to add the MPG widget to his screen.

What prompted this question was my friend was flying with a C172 and they were comparing GPH numbers, and he was tired of calculating the MPG numbers.

Personally, I fly my O-360 powered RV-9 at 150 knots TAS LoP, which gives me between 5.8 and 6.0 GPH. That turns out to be 25 NMPG (or 28.75 SMPG). Those numbers give a zero-wind range of 900 NM (1035 SM) to tanks dry. I suspect I could slow down a little more and get better MPG numbers but at 150 knots I feel like I'm getting somewhere. Also, five hours w/ an hour's reserve is long enough.

 

[airguy]

Showed that picture to a non-aviator friend and he almost expelled his coffee through his nose. We forget sometimes how complicated all this seems to non-aviation folks.

Yeah, I know. I'm off topic.

And yet, when you use it everyday (or at least more days than not), it all seems perfectly comfortable.