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EAA Flight Test Card 4 For Dummies

Vans101

Well Known Member
I am going to do Flight Test #4 the bit where you determine if your pitot/ static/ AS/ altimeter is indicating correctly...

They reference the National Test Pilot School and the following documents:

GPS PEC Method (MS Word document)
GPS PEC Spreadsheets (MS Excel workbook)
Doug Gray's paper (Adobe pdf file)

The spreadsheet they provide is already filled out with someone elses numbers and the method is very complex (it seems like they say "heading" at one plane then they say "fly a track" so it is confusing (at least to me).

Has anyone taken this method and put together a "To Do List For Dummies" checklist that says fly this heading, turn to this heading, turn to... then go to SAAVY and enter this data point in here...then this data pint in there...

And does anyone have a blank spreadsheet for this calculation that has blankes for you to genter the various data and then it does the math>

Any help would be appreciated!!!
 
Here's a much easier way if you've got a glass cockpit

The EAA method is fine, but if you have a glass cockpit with wind readout, you can determine airspeed error it a lot quicker and easier:
* Flying directly upwind, stabilize the plane in cruise. Once stable, fly for one minute. Autopilot is your friend here;
* Turn 180° and fly directly downwind (although when I did it this way, the wind direction had changed 10°. No big deal). After the plane is stabilized, fly for one minute. I do not touch the power controls and do a gentle bank so the speed is little affected. Then I let the plane re-accelerate if it needs to.

Now for the math:
* Average the groundspeed, upwind and downwind.
* Compare the average groundspeed to your true airspeed. This is your error in true airspeed.
* Here’s where you can cheat even more on the math. Suppose your true airspeed is 1.10 times your indicated airspeed, or 10% off. That means that if you were to get out your E6B and calculate how much your indicated airspeed error was, it would be 10% more than your true airspeed error. So suppose your true airspeed error is, best as you can tell, four knots. 10% of four knots is 0.4 knots. Close enough, says me. Don’t have to bother backing the data out to get indicated airspeed error. When I did this method in my RV-9A, doing the math in my head, the true airspeed error was 1 knot, and the indicated airspeed error was also real close to one knot. Close enough, says me.
* For possibly better results, if your glass cockpit recorded the flight data (many do), average the groundspeeds up and downwind, and average the true airspeed. I’ve found it common to see those vary by 2-3 knots in straight and level flight with the autopilot.

Because you were flying pretty close to directly upwind and downwind, this will be pretty close to flying the four headings approach, almost certainly within reasonable limits for amateur flight test. And this technique is plenty good enough for day to day flying.
 
Flight Test Cards for GPS-PEC

I am going to do Flight Test #4 the bit where you determine if your pitot/ static/ AS/ altimeter is indicating correctly...

They reference the National Test Pilot School and the following documents:

GPS PEC Method (MS Word document)
GPS PEC Spreadsheets (MS Excel workbook)
Doug Gray's paper (Adobe pdf file)

The spreadsheet they provide is already filled out with someone elses numbers and the method is very complex (it seems like they say "heading" at one plane then they say "fly a track" so it is confusing (at least to me).

Has anyone taken this method and put together a "To Do List For Dummies" checklist that says fly this heading, turn to this heading, turn to... then go to SAAVY and enter this data point in here...then this data pint in there...

Any help would be appreciated!!!

The referenced documents are available here:
https://www.ntps.edu/images/stories/documents/gps-pec-method.doc
https://www.ntps.edu/images/stories/documents/GPS_PEC.xlsx
https://www.ntps.edu/images/stories/documents/tas_fnl3.pdf

I have used the NTPS GPS-PEC method and incorporated it into the test card that I used for Phase 1 testing of my Cozy Mk_IV. Those test cards, and the rest of the document, are available here:
http://cozybuilders.org/docs/Cozy-MKIV_Flight_Test_Protocol.pdf
and also here as a zipped Word file:
http://cozybuilders.org/docs/Cozy-MKIV_Flight_Test_Protocol.zip
My Flight test protocol is distributed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. You may modify, use, and publish it under the terms of that license.

In my flight card for Flight 4, you fly a constant track (not heading) of the four cardinal headings (not required, but a lot easier to remember while being busy/nervous/excited in test flying a new airplane) at speeds ranging from ~10 KIAS above stall speed to something very far below expected flutter speed. The spreadsheet I used was a simple modification of the GPS-PEC spreadsheet available on the NTPS website linked above.
 
Possibly

The EAA method is fine, but if you have a glass cockpit with wind readout, you can determine airspeed error it a lot quicker and easier:
* Flying directly upwind, stabilize the plane in cruise. Once stable, fly for one minute. Autopilot is your friend here;

Because you were flying pretty close to directly upwind and downwind, this will be pretty close to flying the four headings approach, almost certainly within reasonable limits for amateur flight test. And this technique is plenty good enough for day to day flying.

I would only issue the caution that in most of the glass cockpits, the EFIS is doing the vector math between your ground speed, ground track, KTAS, and heading to solve for the wind vector. Ground speed and track are from your GPS, so the errors there should be small. KTAS is a calculated value based on your indicated airspeed, pressure altitude, and outside temperature. So two of the things you are trying to calibrate (pitot and static) are used in the calculation.

Can you use the ground wind direction to fly two tracks 180 degrees apart and get close? Probably. But if you have significant errors, likely due to static port location and geometry, it can lead to rather significant errors in airspeed, which will cause spurious wind speed and direction calculations.

On my plane I chose (for various reasons) to use static ports that differed from the plans. It lead to significant (~13 knots) errors at the upper end of the tested range (~180 KTAS). Flying two directions based on expected winds would probably have identified a similar error, but having 4 tracks, compared in 3 sets of 3 to generate standard deviation of error really helped nail it do to sub 1 knot errors.
 
Wow

... Those test cards, and the rest of the document, are available here:
http://cozybuilders.org/docs/Cozy-MKIV_Flight_Test_Protocol.pdf
and also here as a zipped Word file:
http://cozybuilders.org/docs/Cozy-MKIV_Flight_Test_Protocol.zip
My Flight test protocol is distributed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. You may modify, use, and publish it under the terms of that license.

...
Kevin, that's really an impressive document. Thanks for sharing it!
 
Thanks!

Kevin, that's really an impressive document. Thanks for sharing it!

Thanks, I appreciate it. Please use it, modify it, cut it up, or use it to keep your parakeet cages clean. As the intro says, I created it out of a lack of similar documents available, and having found many EA-B test pilots essentially at a loss of what to do during their Phase 1. I had been very tangentially involved in the original XP3 Experimental Plane & Pilot Performance by the Experimental Aircraft Association and the Homebuilt Aircraft Council. That effort later turned into the EAA Flight Test Cards that have subsequently been published. So, using that XP3 and AC90-89B, I came up with that protocol.

I would love to have the time to generate the spreadsheets to boil the data down to the "Flight Test Data for Dummies," but I just have not had time. I did mine mostly by importing G3X data into Excel and parsing data.
 
Kevin,

!!!WHOA...THANK YOU!!!

Seriously, I am very grateful for you sharing this flight test plan with the group...thanks again.

When doing the cardinal heading test should the procedure be a constant HEADING or a constant TRACK???
 
Kevin,

!!!WHOA...THANK YOU!!!

Seriously, I am very grateful for you sharing this flight test plan with the group...thanks again.

When doing the cardinal heading test should the procedure be a constant HEADING or a constant TRACK???

I have done a number of these and use the spreadsheet you reference. It is a jewel!

Let me start at the beginning. Get the engine and oil warm and stable. It takes me at least 30 min. Then select a region and altitude that is free of traffic (less busy airspace), and is relatively smooth, like at least 5000ft. I select a heading - say 090, and stabilize and trim, then set the AP. I set the mixture at a ROP point is it does not wander. Then when the IAS is stable, note the time for a data point start, go one minute watching for disruptions, noting the end time. If none, it is good and turn to 330, allow the plane to destabilize after the turn and repeat for another 120 deg left turn. I use the G3X data file will have the GPS track which is what you will want for the spreadsheet. Looking at the VS over the minute and average to see if it is close to zero. Then average the KTAS and record the track and transfer to the spreadsheet.

So there you have it, nothing to it.
 
Thanks Bill,

So the spreadsheet from NTPS looks really impressive and I would be most certainly impressed if I was smart enough to understand how to use it.

I get the part about level altitude, GPS altitude, constant airspeed, GPS ground speed, smooth air, and flying three (or four)...OK is it supposed to be HEADING or TRACK? I would SWAG it is supposed to be TRACK...no?!?!?

Then you pick a different airspeed and repeat...Got it...

The spreadsheet...don't got it...

Does anyone have a spreadsheet that is blank...that has real human words for the fields that you can simply plug and chug and it spits out the numbers?

Or...is it as simple as level off at 100 KIAS and fly four legs N/E/S/W then add up all four GPS ground speeds and divide by four...then...for each leg use an E6B (I hate that thing) and calculate the TAS for each leg and...Oh ****...how do you back track to get calibrated airspeed???
Geez...
 
I am about to go up and do this flight test protocol and I want to verify my Calibrated Airspeed and pitot and static system.

So I get the part about flying three or four headings at a constant altitude and power setting and then letting my EFIS record the data.

Does anyone have the spreadsheet that has blank fields for data that needs to be acquired and I ask because the PEC spreadsheet that the Test Pilot School is already filled out so I was looking for something that made the data points obvious.

Also if you perform this test protocol at only one altitude and only one airspeed then there could be significant static port location errors based on different IAS due to the the different pitch attitudes and or boundary layer turbulence from high speed to low speed so the questions is...I presume you want to do this test at the same altitude but at a number of different IAS from VS+5 to whatever the airplane can maintain with max power in level flight.

Would it be prudent to do this test protocol at a number of different altitudes as well or at least 1000 MSL and then 15000 MSL so as to determine if the altimeter indication is programmed correctly.

Thanks again for your help
 
just math

One thing that's not clear to me, it seems like the EFIS manufacturers are missing an opportunity. They have all the data to figure out if the IAS is accurate or not - why don't they just figure this out for us?

Either manually calibrate it, by telling us to fly a heading and altitude and airspeed, or just gradually figure it out based on the reams of data they have.

Am I missing something?

BTW, here's a sample spreadsheet that might be helpful:

http://www.lightaircraftassociation.../ASI System Calibration 2 Heading Method.xlsx

and more:

http://www.lightaircraftassociation.co.uk/engineering/flight_testing.html
 
GPS-PEC

Does anyone have the spreadsheet that has blank fields for data that needs to be acquired and I ask because the PEC spreadsheet that the Test Pilot School is already filled out so I was looking for something that made the data points obvious.

Also if you perform this test protocol at only one altitude and only one airspeed then there could be significant static port location errors based on different IAS due to the the different pitch attitudes and or boundary layer turbulence from high speed to low speed so the questions is...I presume you want to do this test at the same altitude but at a number of different IAS from VS+5 to whatever the airplane can maintain with max power in level flight.

The GPS-PEC from NTPS is basically the correct way to do this. I have a version of it I modified to only have the 4-leg version, that I have posted here:

https://drive.google.com/file/d/1x1HMf_4LPzMep28HgSx27C-g5JuyUVdl/view?usp=sharing

You can save a copy locally, but you still have to fill it out and fly it. Each test point is a different KTAS point, so record all of the pertinent information (temperature, altitude, indicated airspeed, barometer setting, etc)

Yes, in general this should be flown at a range of altitudes to verify the data. Essentially what you are looking for is "is my static port influenced by airflows at certain speeds or angles of attack and giving me errors?" I will hazard a guess that most people never even bother to determine their pitot-static error at any speed, much less a range. But I found it very informative to fly from as near stall as I could to WOT at three different altitudes (~1000 ft, ~8000ft, and 12,000). What I found was my error at stall at any altitude was nearly zero. My error at WOT was ~13 knots optimistic (displayed 180 KTAS, actual 167). I've been adding steps to my pitot ports since then trying to dial it it. Getting closer, but still not perfect.
 
Heading or track? I don’t know. You can write formulas (different formulas) for either. But I’m with Ed. One source of error for all of these methods is the assumption that the wind is constant. The quickest method (Ed’s) minimizes the total time, so it makes it more likely the wind won’t change. Just make a very gradual turn, monitoring ground speed. Note the heading (it should match the ground track) where the ground speed is maximum. Fly that heading, note gps ground speed. Turn 180 deg and repeat. Average the two ground speeds, that’s your TAS. Use an on-line calculator, or an electronic one, or an E6B, feed in TAS, pressure alt and temp, solve for IAS. Compare to your airspeed indicator.
 
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