Testing at max gross weight

[rleffler]

Originally Posted by Wayne Gillispie

We know the dangers and should inspect the plane before flight.

Like Jon, my FSDO recommended this to me. There was a local crash due to sandbags falling on controls.

Just curious, did FSDO recommend to take people up as part of Phase I? Or as a part of Phase II? Did they put their recommendation in writing?

bob

[LettersFromFlyoverCountry]

John Adams pointed out that my math is off.... 250 is what I need with full fuel, not 350.

But on this question of using a person... how does that work w.r.t. Phase I, the endorsement for emerging from which seems to suggest you test for Vx Vy and stall speeds at all -- or at least the obvious -- weight conditions?

When people enter that wording into their airframe logbook, are they entering the conditions under which the speeds were obtained? Or just entering speeds for one flight condition... normal CG and pilot-only weight?

[jjconstant]

My understanding is that the W&B that you carry with the airplane, that was derived from Phase 1 flight testing, needs to show that the plane has been tested at the extremes of the flight envelop you intend to fly, therefore @ gross weight and aft cg. If the paperwork in the airplane only shows more benign loadings than what you are ramp checked intending to fly with, it's a problem. I could be wrong, but that's why Mel's here

[LettersFromFlyoverCountry]

I don't think the W&B data is derived from flight testing. The W&B, I think, is derived from design and calculations of CG, which wouldn't change in flight testing. The CG is what the CG is, isn't it?

The endorsement in the logbook however, refers specifically to SPEEDS derived in flight testing.

I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operation . The flight test was completed under the following conditions: XXXX

And my operating limitations -- if memory serves -- specifically mentions an indication of V speeds to log.

[airguy]

You'll still need to have a weight and balance ENVELOPE where the airplane will operate - which needs to be populated with data at those min/max points in the corners. The CG doesn't change for an empty airplane - but the balance sure does depending on where you put the useful payload (fuel/passengers/bags).

[Wayne Gillispie]

Bob,

From my Operating Limitations, "During flight testing phase, no person may be carried in this aircraft during flight unless that person is essential to the purpose of flight."

I would not recommend this until nearing the end of phase 1. We both agreed it was essential in the front seat only. The rear seats and baggage area got the dogfood. The other pilot needs to be proficient in same type aircraft and should do a very detailed insp before flight. Both should wear appropriate safety gear. Of course, check with your insurance company too.

[LettersFromFlyoverCountry]

Originally Posted by airguy

You'll still need to have a weight and balance ENVELOPE where the airplane will operate - which needs to be populated with data at those min/max points in the corners. The CG doesn't change for an empty airplane - but the balance sure does depending on where you put the useful payload (fuel/passengers/bags).

I still don't understand. Weight and balance is a mathematical formula. How does the result of that formula change in testing? Similar to the thread on testing VNE, if I load up 200 pounds in the baggage area, even though my W&B calculations say 100 pounds max, and I fly at 1830, instead of 1800, how does that change the W&B calculations which we're required to use to come up with the W&B data.

In other words, if I got the darned thing off the ground in that situation, does that really expand the W&B envelope in any sort of scientific way? What is the data that is populated on existing W&B data?

And, of course, we know the balance is going to change by moving the weight. But how does actually changing it show a different set of results than the mathematical formula which already confirms it's going to change?

It seems to me the point of flight testing here isn't to establish W&B parameters, it's to confirm that the the calculations you've already done, actually are proven correct. (or, unfortunately in some cases, not)

[airguy]

Originally Posted by LettersFromFlyoverCountry

I still don't understand. Weight and balance is a mathematical formula. How does the result of that formula change in testing? Similar to the thread on testing VNE, if I load up 200 pounds in the baggage area, even though my W&B calculations say 100 pounds max, and I fly at 1830, instead of 1800, how does that change the W&B calculations which we're required to use to come up with the W&B data.

In other words, if I got the darned thing off the ground in that situation, does that really expand the W&B envelope in any sort of scientific way? What is the data that is populated on existing W&B data?

And, of course, we know the balance is going to change by moving the weight. But how does actually changing it show a different set of results than the mathematical formula which already confirms it's going to change?

It seems to me the point of flight testing here isn't to establish W&B parameters, it's to confirm that the the calculations you've already done, actually are proven correct. (or, unfortunately in some cases, not)

Ok, I misunderstood where you were coming from on that initial post. True, the calculations used won't change, but you can't operate in Phase II in a region of the W&B envelope that has not been explored during Phase I, at least as I understand the regs. If you don't explore the GTOW with max aft CG during Phase I you can't take off in that condition during Phase II. Now you can specify your envelope for Phase II as long as you have fully explored it during Phase I....

[LettersFromFlyoverCountry]

Originally Posted by airguy

Ok, I misunderstood where you were coming from on that initial post. True, the calculations used won't change, but you can't operate in Phase II in a region of the W&B envelope that has not been explored during Phase I, at least as I understand the regs. If you don't explore the GTOW with max aft CG during Phase I you can't take off in that condition during Phase II. Now you can specify your envelope for Phase II as long as you have fully explored it during Phase I....

ah, OK. and of course that brings up new questions.

The farthest aft CG I can get in the W&B envelope, as near as I can tell...is to run on about 5 gallons of fuel...put four 25-pound bags of shot on top of each other against the baggage bulkhead (yeah, I realize that probably won't support 100 pounds, but this is theoretical), and then put 325 pounds of shot in the passenger seat.

If I can't fly in a particular configuration in Phase II that I haven't tested in Phase I, does that mean I have to also try it with 6 gallons of fuel and 319 in the passenger seat, 7 gallons with 313... and so and and so forth?

I could do a seemingly endless array of configurations in the 10 hours I have left, but by "all regions" of the W&B envelope, but what are the practical arrangements/configurations (i.e. how many and in what configuration) are people using?

Most of the performance charts I've seen over the years have two general configurations. Me by myself and, say, 1/2 to 3/4 full tanks... and me, full fuel, and as much weight as I can stuff to get to gross weight. Is that generally it?

[Snowflake]

Bob, I think the answer you're looking for is that you have to test the "corners" on your W&B graph. How you reach the corner point isn't relevant. If you can get to your aft CG at 1800 lb with a 300lb passenger (or simulation thereof) and 100lb of baggage, or with a 325lb passenger and 75lb of baggage, it doesn't matter, assuming both conditions equate to the same GTOW and CG location.