chazking

chazking

Well Known Member
I plan to replace the right Slick mag with an Electroair system for N1XS (IO540/RV-10). The EI was removed from my previous plane, re-conditioned & certified by Electroair (it's essentially new). So, I'm in a unique position to conduct before / after testing on an EI that may give meaningful empirical results.

My panel has two AFS 5600 (EE & EF) & an AFS 5500T (MFD). The logging should be very useful in capturing data, loading it into excel, smoothing it & creating graphs (etc.) to visualize it for comparison purposes.

What test regimen would VAFers recommend to give useful before & after data?

What are the settings for capturing comparable performance data recognizing this is likely to be on different days with varying atmospheric conditions. For instance, I can see GPH, climb timing, RPM, etc..

And, with your suggestions, please prioritize them by order of importance.

I expect to develop a reasonable test regimen to make this do-able. As Dave Fetherston of Nexair Avionics is fond of saying "Let's not make a science fair project out of it!"

The test regimen should be set by mid-June & results by end-of-June to end-of-July (work schedule & AVWX permitting).
 
I have been doing some testing with fairings and wheel pant mods. I can tell you it is difficult at best to get good data without controlling the environment. My comparison flights are always done withing 1 hour of each other. It will be difficult for you to control the test environment since changing out the mag is not a quick mod.

A good place to start would be measuring fuel flow, airspeed, CHT, and EGT delta at multiple altitudes and atmospheric conditions.

I look forward to seeing the data.
 
Material Differences

Bill, I agree; controlling environmentals is close to impossible - the CAFE Foundation demonstrated that & they used the Jeff Rose config. I doubt that my numbers will come close to their precision!

What's to be demonstrated are material differences, e.g., 10% or more ... otherwise the measurement differences are due to other factors & not material

I'm keenly interested in baselining. Does an EI improve GPH? Seems to, but by how much? If it's 5% one could argue that's a measurement error.

We'll see.
 
Most of the benefits of an electronic ignition can be boiled down to:

-variable timing to help optimize engine performance at less than maximum MAP.

-the ability to fire very lean mixtures and increase fuel economy at cruise.

It's very easy to test the first condition: wire in the timing advance disable switch to the electroair, then test the effect of turning it on or off in flight. The only test condition that can be controlled is <75% wot, leaned to best power mixture. You will need to readjust the mixture for each change in switch position just to be sure.

You will have a hotter spark than a conventional mag, but this will have a negligible effect compared to the timing gains at this mixture condition.

Don't test the second case, your engine may quit.

BTW, the lean cruise is the primary benefit of ei, although ease of starting is sure nice.

V
 
any data collection should also include descriptive information concerning the parameters of your test run. This means that it is not enough to just give the GPH, CHT, EGT, MAP, RPM, speed, altitude, OAT. You need to also give some details concerning the variables for:

MIXTURE
Are you running Full Rich, 100* rich of peak (ROP), 50* ROP, 25* ROP, PEAK, 25* Lean of Peak (LOP), 50* LOP, 100* LOP?

SPEED
Are you using Indicated Air Speed (IAS), True Air Speed (TAS), Ground Speed (GS, not recommended), Calibrated IAS (CIAS)? Are the speeds in Knots (KTS) or Statute Miles (MPH)?

TEMPERATURES
Are the temperatures in Celsius or Fahrenheit?

ENGINE AND PROP INFO
What engine and prop are you running? Is it a carbed 360, fuel injected 320 or ???? Who is the prop manufacturer? Is the prop fixed pitched or constant speed? If fixed pitched what is the pitch of the prop?

ALTITUDE
At what altitude are you testing? Are you using Density Altitude (DA), Pressure Altitude (PA) or just the indicated altitude on your display?

The more detail you can provide, even anecdotal information, the more those details will help clarify things when reporting your findings.

Looking forward to hearing about your results.
 
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I think you should make it simple and about what people really want, better fuel economy.

Have a very defined procedure that you follow for every test flight, something like "I will fly at this speed and this altitude and will lean the engine in this manner until I see this LOP condition, and this is my resulting fuel flow". Do this multiple times with the mag, then multiple times with the EI. Duplicating the procedure many times will eventually factor out atmospheric conditions and allow you to see the trend in fuel flow. Record all available sensor data and the atmospheric conditions for each flight. Days that are obvious atmospheric outliers should be avoided.
 
I pretty much always run WOT in cruise, or just slightly off the stop. So for me, my testing was at my best power ROP mixture speed vs. fuel burn for different RPM.

At altitudes where I'm 75% power or less I set my MAP (all in) and desired RPM (I used a few 2,600, 2,400, 2,300) then leaned and recorded EGT/CHT and KIAS at each .2gph difference. That allowed me to determine best econ and best power gph settings.
 
walkman said:
I pretty much always run WOT in cruise, or just slightly off the stop. So for me, my testing was at my best power ROP mixture speed vs. fuel burn for different RPM.

At altitudes where I'm 75% power or less I set my MAP (all in) and desired RPM (I used a few 2,600, 2,400, 2,300) then leaned and recorded EGT/CHT and KIAS at each .2gph difference. That allowed me to determine best econ and best power gph settings.
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This information is an example of needing at least one of those details I mentioned in my previous post. Since this post did not specifically state so, I have to make an assumption based upon what information was provided and my own experiences in understanding reading about engine performance to conclude that this is an example of running with a constant speed prop.

Because it was noted:
I set my MAP (all in) and desired RPM (I used a few 2,600, 2,400, 2,300)
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I am assuming this pilot can manipulate the MAP and RPM independently, and subsequently he must be running a constant speed prop. If that information is mentioned up front I would not be left with having to try to determine that information from indirect comment(s) that may or may not be descriptive enough. Or, having a misunderstanding of what is being conveyed as it relates to a fixed pitched prop airplane. My understanding of what is being communicated could very well be suspect because I am making assumptions on the configuration and setup of the test aircraft and comparing those to my airplane's configuration and setup. This misunderstanding could lead me to conclude that my testing should result in similar outcomes. However, if my airplane has a fixed pitched prop I would not be able to accurately duplicate the results. Knowing up front whether a test airplane is setup with a constant speed or fixed pitched prop would be important information to know while reading the reported outcome of a test.
 
Simple tests, Logging EGT, CHT, MP, RPM, Fuel Flow, Airspeed and Altitude, and DA is nice at one second intervals.

Fly a full rich full MP/RPM take off, and lean back to a target EGT in the climb at 2000' intervals. all the way to say 8500', then level out, set 2500RPM (still WOT) and lean to 10-20dF LOP.

Do the same for both and lets see what you get. Unless you test exactly like this it will be hard to do comparisons with all the other variables.

Depending on the amount of advance (they all do too much) the result will be something like this, lower EGT (Pv=nRT) higher CHT in all conditions.
 
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I think a very important feature is to be able to test them close to the same time, if not the same day. If you really want meaningful results and to "feel" the difference, the option of hooking up and wiring in the Electroair and getting it running, while leaving the mag wired and plug wires in, then switching back to the mag for a shirt time after running the EI may give you a good "feeling" for the difference and also give you good data for posting.
 
Plan your flight, fly your plan

Ch?z:

Once you settle on the metrics (fuel flow? EGT? CHT? TAS?...) recommend you reduce variables where you can: conduct all testing at a selected Density Altitude for consistency. The late Bob Axsom set a good example of consistency in his testing. This also reduces the number and duration of flights; more data isn't always better.

Optional flights at other altitudes can be planned, if required, to confirm trends or repeat specific events.
 
RVbySDI said:
This information is an example of needing at least one of those details I mentioned in my previous post. Since this post did not specifically state so, I have to make an assumption based upon what information was provided and my own experiences in understanding reading about engine performance to conclude that this is an example of running with a constant speed prop.

Because it was noted:

I am assuming this pilot can manipulate the MAP and RPM independently, and subsequently he must be running a constant speed prop. If that information is mentioned up front I would not be left with having to try to determine that information from indirect comment(s) that may or may not be descriptive enough. Or, having a misunderstanding of what is being conveyed as it relates to a fixed pitched prop airplane. My understanding of what is being communicated could very well be suspect because I am making assumptions on the configuration and setup of the test aircraft and comparing those to my airplane's configuration and setup. This misunderstanding could lead me to conclude that my testing should result in similar outcomes. However, if my airplane has a fixed pitched prop I would not be able to accurately duplicate the results. Knowing up front whether a test airplane is setup with a constant speed or fixed pitched prop would be important information to know while reading the reported outcome of a test.
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Point taken, I made an assumption. Yes, I run a C/S prop
 
esco said:
Ch?z:

Once you settle on the metrics (fuel flow? EGT? CHT? TAS?...) recommend you reduce variables where you can: conduct all testing at a selected Density Altitude for consistency. The late Bob Axsom set a good example of consistency in his testing. This also reduces the number and duration of flights; more data isn't always better.

Optional flights at other altitudes can be planned, if required, to confirm trends or repeat specific events.
Click to expand...

Unfortunately, it's not that simple. Density altitude is a function of pressure altitude, temperature and humidity (small effect). Two density altitudes that are the same, but with a large difference in pressure altitude (and therefore temperature) will give you different performance.

It's right there on the Lycoming performance charts. The temperature correction for engine performance is NOT the same as the temperature correction for density altitude.

I have seen many aircraft mods proclaimed successful because when tested at the 'same' density altitude, there were a few extra knots gained. While it may be true that the airframe only sees density altitude, the engine sees a different function.

There be dragons there.
 
Fly it as per my post, we can adjust for the variables.

If you try to do the same for variables you wll never fly again.

Some can see past the difference.
 
Density Altitude suggestion - noted

Vern:

Thanks for the reminder of the separate effect of temperature; my suggestion to "only look at DA" missed that factor.

Now to reconsider my own flight test results...
 
Many excellent comments here regarding measurement of the desirable results. One that will be affected is heat rejection to the piston and possibly to the oil, especially if there are cooling jets.

I suggest that you also include oil temperature and hopefully the back to back test will be similar in ambients. When I ran an engine development test cell I often tried to test several things, then retest the baseline to ensure nothing unknown had changed. Not essential, but offered for your consideration.

If the vernatherm is fully open and the cooler is getting all the oil it can handle in all tests, then it will provide good comparison. If it is cooler out, then you may find no effect. In fact, you may find no effect anyway if there is not much oil contact with the pistons, but the pistons will be hotter. It may show up as slightly elevated CHT's as cylinder temps are not measured.

Thanks for taking the time to document this effect. It is appreciated.
 
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