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  #1  
Old 06-19-2022, 06:16 AM
edclee's Avatar
edclee edclee is offline
 
Join Date: Aug 2008
Location: Lancaster, SC
Posts: 284
Default Phase 1 Testing: Max Gross?

Operating Limits show need for testing speeds and specifies weight at that testing. Question is: Is it a requirement to test the aircraft at maximum gross weight and at the max forward and aft CG limits the kit manufacturer has designed for.
Ed
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  #2  
Old 06-19-2022, 06:38 AM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,507
Default YES. If you want to operate to those limits.

Quote:
Originally Posted by edclee View Post
Operating Limits show need for testing speeds and specifies weight at that testing. Question is: Is it a requirement to test the aircraft at maximum gross weight and at the max forward and aft CG limits the kit manufacturer has designed for.
Ed
There should be a paragraph within your phase II operating limitations that states:

The pilot in command must not perform any maneuvers that have not been flight-tested or operate the aircraft outside the weight, airspeeds, and center of gravity limits tested. (51)
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Mel Asberry, DAR since the last century. Over 1,000 certifications accomplished. Discount for Veterans, Law Enforcement, Fire Fighters.
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Recipient of EAA Tony Bingelis Award and Wright Brothers Master Pilot Award
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RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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  #3  
Old 06-19-2022, 06:41 AM
N427EF N427EF is offline
 
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Posts: 1,682
Default Gross weight

I can't tell you what you should or should not do and I do not recall the wording in the regs.
I can tell you what I did in my RV-8 and -10 for phase 1 testing.
For the last 10 hours of the 40 hour test period I loaded my 10 up to max gross weight
for testing in all configurations.
It was fairly easy to do in the -10, loading a number of sandbags into the rear seats and max load into the baggage compartment.
W&B software makes shifting weights a simple task to achieve max forward cg and max rear cg.
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  #4  
Old 06-19-2022, 09:08 AM
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testwest testwest is offline
 
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Location: Spruce Creek Fly-In, FL
Posts: 51
Default

Mel is correct.

During the last bit of phase 1, it is prudent to determine and/or check two items at max gross weight:

Stall Speed: This is done at max gross weight and forward c.g. It is the worst case for lift and elevator effectiveness and will result in the highest calibrated airspeed for stall for 1 g flight. That becomes your Vs (or Vso for landing configuration).

Stall Characteristics: This is done at max gross weight and aft c.g. The stall speed will be a little slower since the horizontal tail downforce will be less, but there may be changes in stall buffet and control force gradients that could be more adverse than at other c.g. locations.

There are plenty of other performance items that can be characterized at MGW, but in my opinion these two are very important from a safety of flight perspective.
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  #5  
Old 06-19-2022, 10:05 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Location: Savannah, GA
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Default

Another way of looking at this -- if the plane has some characteristic that you might be uncomfortable with, would you rather find it in benign test conditions in Phase 1 or fully loaded, including loved ones?

Same goes for a newly purchased airplane if there's no CFI to give you a full envelope checkout. For example, my RV-9A, power off, will develop quite a sink rate if slow on final.

Y'all be careful out there!

Ed
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  #6  
Old 06-19-2022, 10:15 AM
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Draker Draker is offline
 
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Location: O61
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Default

From the operating limitations quote Mel gave, I read it as: you need to test any configuration (weight, CG, speed, load factor, attitude) during phase 1 that you plan to fly in during phase 2--but not every possible configuration the plane can be in. For example, my plane with me in it and full fuel has a C.G. approx. 3-3/8" aft of Van's forward C.G. limit. Unless I go on a diet or let my 10 year old fly it solo, it's impossible to fly it in phase 2 with a C.G. further forward than that. So it seems pointless to test it all the way up to the forward design limit. How would you even do that? Ballast in the engine compartment?

My "plain english" take-away from the operating limitations is: Don't fly in phase 2 in any part of the envelope that wasn't tested in phase 1. Is that the gist of it?
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  #7  
Old 06-19-2022, 10:20 AM
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Roadjunkie1 Roadjunkie1 is offline
 
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Location: Erie, Colorado
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Default Flight testing W&B

Agree with all of the above. To know your airplane, you have to have flight-tested it in all of the possible configurations you may encounter as you put her to good use. I would suggest doing the weight loading incrementally; don't immediately put in gross weight at the most forward or rearward CG. It may be obvious that you have to gradually increase the weights at the extremes of the CG as the flying characteristics will be different as those parameters are met. And that can be impressive! I remember the first time I had a 190 pounder in the back seat of SuzieQ! No baggage. W&B figured out before we took off. Having sand back there is WAY different than a breathing human being! I'm glad I had experienced that in my flight testing with something inert!

And it may also be obvious (but I could tell you stories....): Portland cement is much more dense than sand; weight in a smaller package. DO NOT USE PORTLAND CEMENT as your weight. Sand flying around in your cabin is a drag; cement can be deadly!. Yeah, you think that would be obvious but....... Makes me shudder to even think......
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  #8  
Old 06-19-2022, 10:34 AM
Kyle Boatright Kyle Boatright is offline
 
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Location: Atlanta, GA
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Default

Quote:
Originally Posted by Roadjunkie1 View Post

And it may also be obvious (but I could tell you stories....): Portland cement is much more dense than sand; weight in a smaller package. DO NOT USE PORTLAND CEMENT as your weight. Sand flying around in your cabin is a drag; cement can be deadly!. Yeah, you think that would be obvious but....... Makes me shudder to even think......
If you do use a granular material - sand, gravel, portland cement, dog food, whatever...Double bag it. You'll greatly reduce the chances of needing to deal with "Cleanup on Aisle 5".
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  #9  
Old 06-19-2022, 10:37 AM
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edclee edclee is offline
 
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Location: Lancaster, SC
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Default Phase 1

Quote:
Originally Posted by Mel View Post
There should be a paragraph within your phase II operating limitations that states:

The pilot in command must not perform any maneuvers that have not been flight-tested or operate the aircraft outside the weight, airspeeds, and center of gravity limits tested. (51)
Mel, I agree completely. The reason I posted the question is that having looked at the logs of several people I know who built their aircraft, there is no statement of critical speeds found at full aft CG and max gross weight. One such aircraft based here whose owner did not build the aircraft is flying to Canada in his Highlander at 1550 lbs, which Just says is OK and tested by them as safe, has only a logged 1134 lbs and associated speeds before being put in Phase II. This could be a problem in Canada if challenged by the Canadian authorities on a ramp check. Note only did the builder not realize it, nor did the FAA FSDO inspector who was asked about it. When I built my Sonex I used lead shot and sandbags to achieve the limits. In many cases however it is virtually impossible to get to the forward CG limit. The RV10 being a notable exception.
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  #10  
Old 06-19-2022, 07:28 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
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Default Testing

Some believe that the EAB category of Experimental originated with EAA. It actually originated well before EAA but there was not a lot of activity.
EAA held their first meeting in Jan 1953. In Jan 1953 Steve Wittman made the first flight of the W8, later named Tailwind. In Dec 53 Steve tested the W8 in the presence of CAA Inspector. Gross weight, dive to 110% of Vne while taking a picture of airspeed and 4G load test.
after the successful test the Tailwind became the first EAB airplane certified to carry a passenger.
The next four Tailwinds were tested to the same criteria with CAA observing.
One almost met with disaster. At 110% of Vne a sandbag slipped out of place and pushed the stick forward. By the time the pilot got things under control airspeed was near 300 and G meter recorded 8.3 positive and 3.8 negative.
This became known as the "Sandbag Tailwind." It still exists and is being rebuilt.
It was also the only four place Tailwind. With two young boys in a jump seat and two adults in front it made a round trip from Madison WI to LA. 90 horsepower.
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