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Flight test dummy?

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cluttonfred

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No, I am not teasing anyone, just wondering about how someone might flight test a two-seater at full gross weight with just the pilot aboard. You want the weights to be as close as possible to where they'd be with a second person aboard, but everything has to be very secure. An actual 180 lb "dummy" would be pretty darn awkward to load and unload and the feet could foul the pedals.

What would be good is some sort of system (sandbags or what have) that you load in stages but connect together and strap in like a person for the flight. Anyone know of any good solutions?

The only thing I have come up with is a large backpack that you strap in the seat like a person plus a smaller bag buckled to the first one on the floor in front of the seat. Thighs to feet is about 1/3 of total human weight so call it about 120 lb in the big bag and 60 lb in the smaller one in 20 or 30 lb increments?
 

pictsidhe

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If it would fit, a 25 gallon drum. Strap it in so its cg is about whete that of a passenger would be, then fill with water. Siphon the water out before removing it.
 

cluttonfred

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Strapping in a 25 gal drum might not be very easy, but 5 gallon plastic jugs could work well with straps/bags to hold them down.
 

lr27

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Suggest that anything used should be quite strong and secure. NOT sand or cncrete bags unless they're inside something stronger. Double straps, etc.
 

Daleandee

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I used 50 pound bags of play sand from the Home & Aviation Depot. 4 for my 200 pound dummy:

When finished they were gifted to the grand-kids ...

Dale
N319WF
 

Tiger Tim

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The airliner prototypes use water tanks to mess with weight and balance on test flights, photos of a cabin full of tanks are often used to prove chemtrails are real.

The conspiracy theorists don’t seem to realize that a bunch of tiny tanks are very inefficient compared to a single large tank often found under the floor of a passenger-carrying plane. Oops, shouldn’t have said that.
 

jedi

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Sahuarita Arizona, Renton Washington, USA
No, I am not teasing anyone, just wondering about how someone might flight test a two-seater at full gross weight with just the pilot aboard. You want the weights to be as close as possible to where they'd be with a second person aboard, but everything has to be very secure. An actual 180 lb "dummy" would be pretty darn awkward to load and unload and the feet could foul the pedals.

What would be good is some sort of system (sandbags or what have) that you load in stages but connect together and strap in like a person for the flight. Anyone know of any good solutions?

The only thing I have come up with is a large backpack that you strap in the seat like a person plus a smaller bag buckled to the first one on the floor in front of the seat. Thighs to feet is about 1/3 of total human weight so call it about 120 lb in the big bag and 60 lb in the smaller one in 20 or 30 lb increments?
I order a few bags of pennies from my bank. I can return the pennies after the testing is complete. Pennies are in strong bags and smaller than an equal weight of sand, etc. don’t break the seal and the bank doesn’t complain two much.

It costs more but you get a 100% refund. If you take time to search for wheat pennies and other older coins you can even make a profit, something nearly impossible in aviation these days.
 

lr27

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I don't see why the chemtrail people don't just say it's done by water bombers when there's no fire.
 

bifft

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Doing this on my RV right now. Putting the sand bags in an old military duffel bag, and then strapping that down with the seatbelts. It is probably a bit further back than a real passenger as it doesn't have "legs" pointing forward.
 

bifft

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Since the weather was good enough to fly today, uploaded this in case anybody wants to see what 180 lbs of sand in a duffel bag looks like. Used the "tube sand" which is 60 lb long skinny sacks. Fits in better than the square bags. Only cost about $5.00 each, got four of them to test up to 240 lbs (which is a big a passenger as I can take and stay in CG range. Also using two 25lb sacks of flour for the 50 lb limited front baggage. Not sure I can fit the fourth in the bag.
 

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bifft

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Apr 17, 2011
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A bit of a follow up to this. I left the 180lbs of sand in the plane for a few weeks while the weather wasn't good enough to fly. Put in one more 60 lb tube today for my final CG expansion and gross weight test. When I landed and unloaded all of the sandbags were soaking. Looks like it absorbed water from the air over the weeks of wet weather. Weighed when I got home and had an extra couple of pounds of water weight.

So, tested at 1802 instead of 1800 lbs. Close enough for me, but something for others to watch out for. Have the sand out where it can breath and dry out when you aren't using it.
 
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