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  #1  
Old 07-27-2020, 03:49 PM
Vans101 Vans101 is offline
 
Join Date: Apr 2016
Location: San Jose
Posts: 60
Default EAA Flight Test Card 4 For Dummies

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!!!
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  #2  
Old 07-28-2020, 09:00 AM
PhatRV PhatRV is offline
 
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Default

Are there links to the three document you referenced in your post?
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  #3  
Old 07-28-2020, 11:34 AM
Ed_Wischmeyer's Avatar
Ed_Wischmeyer Ed_Wischmeyer is online now
 
Join Date: May 2005
Location: Savannah, GA
Posts: 1,326
Default 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.
* Heres 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. Dont 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. Ive 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.
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  #4  
Old 07-28-2020, 12:48 PM
krwalsh krwalsh is offline
 
Join Date: Nov 2009
Location: San Francisco, CA
Posts: 359
Default Flight Test Cards for GPS-PEC

Quote:
Originally Posted by Vans101 View Post
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/...pec-method.doc
https://www.ntps.edu/images/stories/...s/GPS_PEC.xlsx
https://www.ntps.edu/images/stories/...s/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-MK...t_Protocol.pdf
and also here as a zipped Word file:
http://cozybuilders.org/docs/Cozy-MK...t_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.
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  #5  
Old 07-28-2020, 01:48 PM
krwalsh krwalsh is offline
 
Join Date: Nov 2009
Location: San Francisco, CA
Posts: 359
Default Possibly

Quote:
Originally Posted by Ed_Wischmeyer View Post
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.
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  #6  
Old 07-28-2020, 02:34 PM
rv8ch's Avatar
rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGY
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Default Wow

Quote:
Originally Posted by krwalsh View Post
... Those test cards, and the rest of the document, are available here:
http://cozybuilders.org/docs/Cozy-MK...t_Protocol.pdf
and also here as a zipped Word file:
http://cozybuilders.org/docs/Cozy-MK...t_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!
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  #7  
Old 07-28-2020, 03:00 PM
krwalsh krwalsh is offline
 
Join Date: Nov 2009
Location: San Francisco, CA
Posts: 359
Default Thanks!

Quote:
Originally Posted by rv8ch View Post
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.
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  #8  
Old 08-07-2020, 07:36 PM
Vans101 Vans101 is offline
 
Join Date: Apr 2016
Location: San Jose
Posts: 60
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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???
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  #9  
Old 08-07-2020, 07:51 PM
BillL BillL is offline
 
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Location: Central IL
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Quote:
Originally Posted by Vans101 View Post
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.
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  #10  
Old 08-08-2020, 11:30 AM
Vans101 Vans101 is offline
 
Join Date: Apr 2016
Location: San Jose
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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...
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