Buratinu Maxi 1600

After Hans-Juergen tested the Buratinu 1300 I designed middle wing parts to expand the wingspan to 1600 mm.
Many thanks again Hans-Juergen, for printing and testing it for me!
This is way the Buratinu 1600 version was born ;)

https://youtu.be/ne5Z_o-d_dA

This is his detailed report
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Weather conditions during testing:
Morning from 10 am, temperature about 6-8 degrees, cloudless sky, weak wind from NW with maximum 5 km/h and negligible thermals.
The results are quite interesting, but in the end had almost been expected.
The (safe) center of gravity is actually 190 mm measured from the end of the fuselage. I had to add 20 grams of lead at the height of the front cover under the fuselage to keep the center of gravity because of additionally installed cables and telemetry sensors. The takeoff weight is thus 870 grams, the wing loading about 26 g/sqm.
I changed the motor and mounted an Extron 2217/16 (KV 1140, 28 mm diameter and 33 mm length) on a 9" x 6" folding propeller. It draws 22 amps on the 3S/1000 battery when stationary. This makes for an exceptionally good motorization.

The elevator is set to about 3 mm depth (measured on the outside of the rudder to the wing) at neutral stick position. This is absolutely necessary, otherwise the Buratinu-1600 will rise mercilessly when the elevator is in neutral position.
Furthermore, add about 15% depth for the motor in proportion to the motor power. With these settings and a good amount of Expo (50%) on all rudders, the Buratinu shows a very balanced flight behavior.

Hand launching is absolutely no problem with a little push from the hand. I was really surprised by the "creep ride" of the Buratinu.
I tried to "starve" it several times in glide to see the behavior during stall. I had to wait a long time and then it merely took the nose down slightly to pick up speed.The 1600 is a comfortable flyer with good ambitions for a relaxed flight in thermals. But I'm sure that will be fleshed out in the next few flights. I have flown the GPS logger with pressure sensor and TEC probe (the small rod on the back of the fuselage) on a trial basis to test whether the data is sufficient for measurements in the future.

I also made a small video of one of the flights - the weather was perfect for that. But since the Buratinu often moved at an altitude of about 80 to 100 meters, I had to cut away a lot, because only the blue sky was visible on the pictures. But I think the video still clearly shows where the strengths of this thermal glider is.
The picture below shows the course of the flight after which the glide phases are to be analyzed.

If you want to have a look at it from all sides in Google Earth, here is the link to the kmz:
https://my.hidrive.com/share/l9qq-eq951#$/

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All other needed parts can be downloaded from Buratinu 1000

The special thing about this version also is that all parts of the wing, i.e. W3 to W5 as well as the elevons are identical to the original Buratinu version which are included here:
https://www.thingiverse.com/thing:3047415
The wingend W6 is smaller. You must take it from the Buratinu Midi 1000
https://www.thingiverse.com/thing:4280142
Or in case you can print larger, you can take the parts from here:
https://www.thingiverse.com/thing:3857570
The Buratinu 1300 uses the same fuselage as the Buratinu Midi.
So you have to take it from here:
https://www.thingiverse.com/thing:4280142

Specifications
airfoils: own design
wing span: 1600 mm
wing chord: 284/140 mm
CoG: 190 mm from rear edge of the fuselage
overall weight: 870 g (PETG/LW PLA)
wing area: 35 dm²
wing loading: 25 g/dm²
motor: Extron 2217/16 1140 KV max 250W
folded propeller: 9 x 6"
battery: 1000 mAh 3S 30C
motor camber: -4°

Print Settings
Wings
perimeter_extrusion_width = 0.5
layer_height = 0.25
perimeters = 1
fill_density = 0%
bottom_solid_layers = 4
top_solid_layers = 4

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